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SOIL and CROP SCIENCE SOCIETY of FLORIDA

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PROCEEDINGS VOLUME 65

2006

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SIXTY-FIFTH ANNUAL MEETING DOUBLETREE GUEST SUITES

BOCA RATON, FLORIDA 18-20 MAY 2005

Mission Statement for Soil and Crop Science Society of Florida

The objectives of the Soil and Crop Science Society of Florida shall be those of an educational and scientific corporation qualified for exemption under Section 501 (c)3 of the Internal Revenue Code of 1954 as amended, or a comparable section of subsequent legislation. The mission of the Society is: 1) To advance the discipline and profession of soil and crop science in Florida a) by fostering excellence in the acquisition of new knowledge and in the training of scientists who work with crops and soils, b) through the education of Florida citizens, and c) by applying knowledge to challenges facing the State, and 2) to contribute to the long-term sustainability of agriculture, soils, the environment, and society by using scientifically-based principles of soil and crop science to promote informed and wise stewardship of Florida's land and water resources.

The Soil and Crop Science Society of Florida provides a non-regulatory and non-political forum to foster scientific ideas and exchange of in-formation for those interested in agricultural production and the sustenance of the agro-ecosystem in Florida. The mechanisms by which this so-ciety fosters exchange and displays of objective information include: 1) The presentation, at annual meetings, of papers by those who have completed scientifically-designed and analyzed data on subject matter that is pertinent to agriculture and environmental quality. 2) The publication of scientifically-designed treatments and analyzed experiments in papers on specific subject matters that are peer reviewed and published in a long-standing series of the Proceedings (Soil and Crop Science Society of Florida Proceedings). 3) The publication of position papers in the Proceedings that are needed by those who design laws and statutes on contemporary and applied subject matters related to agriculture and the environment in Florida that require objective viewpoints based on scientifically-attained information. 4) The fostering and training of students to participate in sci-entific dialogue by providing them with a competitive forum at the annual meeting of the Society where they can present their scientifically-attained data on agriculture and the environment and by providing them with opportunities to interact with professional people from universities, commer-cial companies, agribusiness, and growers. 5) The establishment of educational credits (e.g. C.E.U.s) which allow professionals to maintain their competency and certified status.

Drs. G. H. Snyder and T. A. Kucharek, January 2000.

Logo of the Soil and Crop Science Society of Florida. At the 40th Annual Business Meeting at 1120 h, 8 Oct. 1980 at the Holiday Inn, Longboat

Key, Sarasota, FL, a report was presented by the ad hoc Logo Committee composed of J. J. Street, Chair, R. S. Kalmbacher, and K. H. Quesenberry. All Society members were eligible to participate in the contest which would result in the selection of a logo design for the SCSSE The presentation of the winning entry would be made at the 1981 Annual Meeting. David H. Hubbell was announced as the winner of the contest and was awarded a free 10-yr membership in the Society. The design, shown above, depicted the chief interests of the Society: Florida Soils, and Crops. Soils and Crops were given equal weight with Florida. Soils was depicted as the soil texture triangle which shows the percentage of sand, silt, and clay in each of the textural classes, but simplified so as to permit clarity in reduction when printed. Crops was shown as a stylized broadleaf plant, including the roots. Florida was shown, minus its keys, with only one physical feature in its interior, Lake Okeechobee. Enclosed within nine rays such as might be envisioned as being made by the sun emitting light (sunburst) behind the symbols are two concentric circles containing the words "SOIL AND CROP SCIENCE SOCIETY" in the top semicircle and "FLORIDA" at the bottom of the lower semicircle. A schematic likeness of the State of Florida occupies 0.5 of the area within the smaller circle, while the symbol for Soils and the symbol for Crops occupy 0.25 of the area each, with the sum of the three parts totalling unity.

The first printing of Society stationery following the award on 28 Oct. 1981, and the printed program of the Society since the 1982 meetings, have featured the logo.

V. E. Green, Jr., Editor, Volume 45

2005 OFFICERS SOIL AND CROP SCIENCE SOCIETY OF FLORIDA

VOLUME 65 CONTENTS 2006President ……………………….….. Bill Thomas

Columbia Co. Extension Office Rt. 18, Box 720 Lake City, FL 32025

Dedication ……………………………………………………………………………………………………………………….. v

President-Elect ……………….......… Ken Boote Dept. of Agronomy P.O. Box 110500 Gainesville, FL 32611-0500

CROPS & FERTILIZATION PRACTICES

Determining Ammonium and Nitrate Using a Gas Sensing Ammonia Electrode ….. D. W. Rich, B. Grigg, and G. H. Snyder 1 Effect of Irrigation and Gypsum Application on Aflatoxin Accumulation in Peanuts

Secretary-Treasurer………………T. A. Obreza Soil & Water Science Dept. P.O. Box 110510 Gainesville, FL 32611-0510

P. J. Wiatrak, D. L. Wright, J. J. Marois, and D. Wilson 5

Biomass Yield and Forage Nutritive Value of Cynodon Grasses Harvested Monthly …………… P. Mislevy and F. G. Martin 9 Directors: St. Augustinegrass Phosphorus Requirement Using Hydroponic Culture

Min Liu, J.B. Sartain, L.E. Trenholm, G.L. Miller, and P. Nkedi-Kizza 15

M. B. Adjei (2005) Range Cattle REC 3401 Experiment Stn. Ona, FL 33865-9706

ENVIRONMENTAL QUALITY

Commercial Microbial Inoculums and Their Effect on Plant Growth and Development: A Synopsis of Current Literature and

Case Studies ………………………… P. G. Kalogridis, J. M. S. Scholberg, R. J. McGovern, R. B. Brown, and K. L. Buhr 21Lena Ma (2006)

Soil & Water Science P.O. Box 110290 Gainesville, FL 32611-0290

Guidelines for Compost Sanitation

R. N. Inserra, M. Ozores-Hampton, T. S. Schubert, J. D. Stanley, M. W. Brodie and J. H. O’Bannon 31

Agronomic Impact of Land Applied Water Treatment Residuals (WTR) …. O. O. Oladeji, J. B. Sartain and G. A. O’Connor 38

Greg McDonald (2007) Dept. of Agronomy P.O. Box 110500 Gainesville, FL 32611-0500

NEMATOLOGY - PLANT PATHOLOGY EDITORIAL BOARD Effect of Fungicide Application Timing on Defoliation of ‘Valencia’ Orange by Greasy Spot in Southwest Florida Editor: R. J. McGovern, A. A. Stoddard III and B. M. Cauley 49

Effects of Solarization and Ammonium Amendments on Disease and Yield in Snap Bean and Summer Squash R. J. McGovern, R. McSorley, T. E. Seijo, T. A. Davis and K.-H. Wang 52

Mimi Williams USDA-NRCS 2614 NW 43rd Street Gainesville, FL 34606-6611

Associate Editors:

GRADUATE STUDENT FORUM

ABSTRACTS Gilbert Sigua (Soil and Water)

Subtropical Agric Research Station REC 22271 Chinsegut Hill Road Brooksville, FL 34601-4672

Transport of Water, N-forms, and Potassium Through Plastic Mulched Beds Cropped with Vegtables Under Drip Irrigation

K. A. Mahmoud, P. Nkedi-Kizza, J. B. Sartain, E. H. Simonne, M. D. Dukes and R. S. Mansell 58

Chemical Characterization and Mineralization Rates of Selected Biosolids and Organic Wastes Ed Hanlon (Soil and Water)

Southwest Florida REC – Immokalee 2686 Hwy 29 N Immokalee, FL 34142-9515

C.B. Reis, J. B. Sartain, J. E. Rechcigl, C. D. Stanley, M. B. Adjei 58

Characterization of Sorption of Pesticides Applied to Carbonatic Soils of South Florida and Puerto Rico G. Kasozi, P. Nkedi-Kizza, W. Harris, Y. Li, D. Hodell, and D. Powell 58

Ike Ezenwa (Crops) Southwest Florida REC – Immokalee 2686 Hwy 29 N Immokalee, FL 34142-9515

Capillary Fringe Associated with Hydrologic Soil Indicators at Sandhill Lakes ………… T.C. Richardson and P. Nkedi-Kizza 59St. Augustinegrass Phosphorus Requirement Using Hydroponic Culture

Min Liu, J. B. Sartain, G. L. Miller, W. G. Harris, P. Nkedi-Kizza, R. L. Wu 59Hartwell Allen (Crops)

Dept. of Agronomy P.O. Box 110965 Gainesville, FL 32611-0965

Application of DSSAT for Simulating Nitrogen Response of Sweet Corn

C. M. Cherr, J. M. S. Scholberg, K. J. Boote, and M. D. Dukes 60

Bob McGovern (Entomology-Nematology)

Plant Medicine Program P.O. Box 110680 Gainesville, FL 32611-0680

OTHER ABSTRACTS CROPS AND FERTILIZATION PRACTICES

Elevated CO2 and Temperature Effects on Sugarcane Plant and Ratoon Crops Published annually by the Soil and Crop Science Society of Florida. Membership dues, including subscription to the annual Proceedings, are $30.00 per year for domestic members and $35.00 per year for foreign members. At least one author of a paper submitted for publication in the Proceedings must be an active or honorary member of the Society except for invitational papers. Ordinarily, contributions shall have been presented at annual meetings; exceptions must have approval of the Executive Committee and the Editorial Board. Contributions may be (1) papers on original research or (2) invitational papers of a philosophical or review nature presented before general assemblies or in symposia. A charge of $45.00 per printed page in the Proceedings will be billed to the agency the author represents to help defray printing costs. Members are limited to senior authorship of one volunteered paper per annual meetings; there is no limit for junior authorship.

L. H. Allen, Jr., J. C. V. Vu, J. C. Anderson and J. D. Ray 61

Thermal Units Prediction for Chilling Accumulation and Crop Development in Alabama, Florida and Georgia J. Bellow and C. Fraisse 61

Integration and Verification of Water Quality and Crop Growth Models for BMP Planning K. J. Boote, J. W. Jones, and B. M. Jacobson 61

Forage Yield and Nutritive Value of Urochloa Varieties in Southwest Florida R. M. Muchovej, P. R. Newman, and I. V. Ezenwa 62

Simulating Crop N Balance in Crop Growth Models Used for Best Management Practice Recommendations J. I. Lizaso, K. J. Boote, J. W. Jones and W. D. Batchelor 62

Measurement of Plant-Produced Volatile Organic Compounds in Controlled Environments O. Monje, I. Eraso, J. T. Richards, J. S. Sager and T. P. Griffin 63

Germination and Vigor of Peanut Seed from Six Cultivars as Affected by Production and Storage Location J. M. G. Thomas, K. J. Boote and D. W. Gorbet 63

(continued on next page)

Interactive Effect of P and N Rates on Leaf Anthocyanins, Tissue Nutrient Concentrations, and Dry Matter Yield of Floralta Limpograss during Short Day-length …………………………………….. N. P. Shaikh, M. B. Adjei, and J. M. Scholberg 63

Nitrogen Fertilization of Rice in Florida ……………………………….………………………………………………..…. G. H. Snyder 64

CLIMATE CHANGE EFFECTS

Elevated Temperature Decreases Yields of Seed Grain Crops L. H. Allen, Jr., K. J. Boote, P. V. V. Prasad, R. W. Gesch, A. Snyder, J. M.G. Thomas and J. C.V. Vu 64

Soil Carbon Sequestration Potentials of Bahiagrass and Rhizoma Perennial Peanut in Florida under Current and Global Warming Conditions …………..…………………….. L. H. Allen, Jr., K. J. Boote, J. M. G. Thomas, S. L. Albrecht and K. W. Skirvin 64

Effects of Elevated Temperature and CO2 on Seed Quality and Composition of Annual Peanut J. M. G. Thomas, K. J. Boote, P. V. V. Prasad and L. H. Allen, Jr. 65

ENVIRONMENTAL QUALITY

Fractional Distribution of Phosphorus in Histosols Amended with Increasing Phosphorus Rates Y. Luo, R. Muchovej, R. W. Rice and J. M. Shine, Jr. 65

Cropping Effect on the Chemical and Physical Properties of a Typical Organic Soil in the Everglades Agricultural Area J. L. Pantoja, S. H. Daroub, O. A. Díaz, M. Chen and V. Nadal 66

Arsenic Uptake Released from CCA Treated Lumber by Florida Vegetable Crops ……………….… A. Shiralipour and R.N. Gallaher 66Environmental Effects of Pesticide Use within Lake Victoria Basin, Uganda ……………... J. Wasswa, B. Kiremire, and P. Nkedi-Kizza 66

NEMATOLOGY—PLANT PATHOLOGY

Susceptibility of Cut Flowers to the Root-knot Nematode, Meloidogyne incognita ……………….....….. K.-H. Wang and R. McSorley 67

SOCIETY AFFAIRS 2005 Program Summary ………………………………………………………………………………………………………..…………. 68 Executive Board Meeting, 27 January 2005 …………………………………………………………………………………………... 71 Executive Board Meeting, 18 May 2005 ………………………………………………………………………………………………. 71 Business Meeting, 19 May 2005 ………………………………………………………………………………………………………. 72

Financial Report …………………………………………………………………………………………………………………………….. 742006 Committees ……………………………………………………………………………………………………………………………. 74Membership Lists Regular Members 2005 ………………………………………………………………………………………………………………... 75 Honorary Life Members 2005 …………………………………………………………………………………………………………. 77 Emeritus Members 2005 ………………………………………………………………………………………………………………. 78

Subscribing Members 2005 ……………………………………………………………………………………………………………. 78Historical Record of Society Officers ………………………………………………………………………………………………………. 80List of Honorary Life Members and Editors ………………………………………………………………………………………………... 81List of Dedication of Proceedings …………………………………………………………………………………………………………... 82

Proceedings, Volume 65, 2006 1

CROPS AND FERTILIZATION PRACTICES Determining Ammonium and Nitrate Using a Gas Sensing Ammonia Electrode

D. W. Rich*, B. Grigg, and G. H. Snyder

ABSTRACT

Dependable analyses for NO3--N and NH4

+-N contained in environmental soil and water samples are extremely important. Determinations are generally performed using costly high-maintenance automated equipment, i.e., a Lachat flow injection analyzer (Hach Co., Loveland, CO). Alternatively, NH3 and NO3 can also be determined via their respective ion selective electrodes (ISE), although the NO3

- ISE is of limited use because of multiple interferences. A provisional (old) method that uses TiCl3 to reduce NO3

- to NH4+ ion. This method determines NH4

+ and NO3

- sequentially using the same NH3 ISE. It was later retracted because of reproducibility and accuracy problems. However, we found that these problems can be overcome by altering the concentration of the fill solution for the electrode, and the analysis has no interferences since the electrode detects gaseous NH3 exclusively. The objectives of this study were to investigate the effects of a re-formulated fill solution, compare NO3

- results between the revised (new) NH3 electrode method to those from an automated procedure, and finally to show acceptable analytical recovery. Re-formulating the fill solution of the electrode improved the NO3

- recovery to a range between 90-100%, and comparative results are within 15% of those from an automated procedure.

INTRODUCTION

All plant life processes depend on N compounds. Plants with poor or slow growth, chlorosis, and seedling death exhibit signs that are generally associated with N deficiency (DeDatta, 1987). The oxidation status of N can have an impact on its uptake in certain plants.

In water, the redox status of N is usually related to the degree of contamination (Eaton, 1995). Most N contamination is present as NH3, which over time is oxidized to NO2

- and then to NO3-. Therefore the

determination of NO3--N and NH4

+-N is extremely important due to its implications for environmental health as well as for plant life. Determinations of these two species can be achieved by various methods, i.e., conventional wet chemistry with cadmium reduction (Eaton, 1995), automated (flow-injection) cadmium reduction procedures (Eaton, 1995), and ISE’s for NH3 and

NO3- (Eaton, 1995) respectively. With the exception of

the NH3 ISE, problems such as sample turn-around time, expense of automated equipment, and analytical interferences are associated with the remaining methods.A little known method exists (Eaton, 1995) that utilizes the ability of the NH3 ISE to achieve the combined analysis of NO3

- and NH4+. A provisional (old) methodology, based

on the work of Braunstein et al. (1980), was developed for water analysis.

The Everglades Research and Education Center had used this provisional method, 4500-NO3-G (Eaton, 1995) to test for NO3

- and NH4+ in matrices of soil extracts (using

2M KCl as the extractant) as well as reclaimed percolate water from a golf course.

This method of analysis was discontinued due to the inability of the electrode to detect NO3

- below 2.5 mg kg-1. Poor recoveries as well as excessive coating of the glass electrode tip with AgCl, were significant problems associated with the method. Given these limitations, the main objectives of this investigation were: (a) to study the effects of a new fill solution formulation, (b) to compare NO3

- results from the revised (new) NH3 electrode method to those from an automated procedure, and (c) to show acceptable analytical recovery of NO3

-.

MATERIALS AND METHODS

Standards Preparation

Ammonium standards were prepared by dilution from 0.1M NH4

+ activity standard # 951006 (Orion Research, Beverly, MA.).

Nitrate standards were prepared by dilution from 0.1M NO3

- activity standard # 920706 (Orion Research, Beverly, MA.).

Reagent Preparation

The NH3 electrode filling solution of the provisional method described in Standard Methods, 4500-NO3

- -G (Eaton, 1995) has a NO3

- detection range of 0 to 20 mg kg-1. However, this solution caused problems by coating the interior glass chamber of the electrode with AgCl residue. Slow response and poor reproducibility at the low end of the NO3

- concentration were some of the symptoms.

D. W. Rich, Everglades Res. and Educ. Center, Belle Glade, FL. 33430 (Ret.).; B. Grigg, United States Dept. of Agriculture, Baton Rouge, LA. 70808; G. H. Snyder, Everglades Res. and Educ. Center, Belle Glade, FL. 33430 (Ret.).

*Corresponding author ( [email protected] ). Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:1-4 (2006)

mailto:[email protected]

Soil and Crop Science Society of Florida 2

Adjusting the concentration of the ingredients seemed to correct these problems.

● Common Reagents:

a. 10N NaOH (Eaton, 1995). Use 2.5 ml (for pH adjustment)

b. 20% TiCl3 solution (Eaton, 1995). Use 0.5 ml (for NO3

- reduction)

● Electrode filling solution.

For purposes of comparison, the preparation of both fill solutions (provisional and revised methods) are described.

a. Provisional method. Dissolve 0.54 g of NH4Cl and 8.5 g of NaNO3 and dilute to 100 ml with deionized water. Add 0.3 ml of 0.1M AgNO3. The solution will be slightly cloudy.

b. Revised method. Dissolve 0.35 g of NH4Cl and 9.5 g of NaNO3 and dilute to 100 ml with deionized water. Add 0.2 ml of 0.1M AgNO3. This solution will be slightly cloudy.

The NH3 electrode is filled with ~ 2 to 5 ml of the revised method mixture. The fill solution should be discarded and replaced every 20 to 30 samples.

Sample Preparation

Sample solutions of 25 ml were added to a 3 oz Solo cup (Solo Cup Co.,Urbana, IL.). A stirring bar was added, and the NH3 electrode was then immersed in the spinning solution. After the addition of NaOH, the electrode potential (mv.) was allowed to stabilize or come to a constant potential reading. Once stabilized, the measurement can be recorded for the purpose of calculation in the future. This first measurement is related to the initial [NH4

+-N]. TiCl3 is added to the same spinning sample, to reduce any [NO3

-] to [NH4+], and the electrode

potential is again allowed to stabilize. This measurement is the total [NH4

+-N], and is related to the [NO3-N] by the following equation,

[NH4+-N] (total) – [NH4

+-N](initial) = [NO3-N] Eq. [1]

where,

[NH4+-N] (total) is [NH4

+-N] (initial) + any NO3- that is

converted to NH4+ and [NH4

+-N] (initial) is [NH4+-N] that

doesn’t contain any converted NO3-.

Samples for Method Comparison, % Recovery and Low NO3

- Replication

For these tests, all soil extract samples with high NO3-

were diluted in order to bring them into the usable range of 0.5 to 20 mg NO3-N kg-1 (Eaton, 1995).

Method comparison of NO3- consisted of 45 soil extract

samples and percolate water that were split, and half were

analyzed by an automated NO3- method. The other half of

the samples were analyzed by the NH4+ electrode.

Recovery was obtained by taking 24 duplicate samples of 25 ml each and spiking one of each duplicate with NO3

-. Prior to spiking, each sample was adjusted to 1.0 mg kg-1 of NO3

-. The samples consisted of three groups: soil extracts (SE, n = 10), percolate water samples (PW, n = 10), and 4 deionized water samples (DI). After the NO3- analysis, recovery was calculated by,

% Recovery = (NO3-

found - NO3- sample)/ NO3

- added. Eq. [2]

where,

NO3- found is the original sample with the spiked amount or

the known addition,

NO3- sample is the un-spiked sample of 1.0 mg kg-1 and,

NO3- added is the known addition or the spike.

Two samples were prepared for replication of low concentration NO3

-. Each sample contained 2 mg NH4+-N

kg-1, and labeled 1 and 2. These samples contained 0.5 and 1.0 mg NO3-N kg-1 respectively, and were analyzed six times. A second test was run by the original method for comparison.

Standard deviation and correlation data for the above three investigations were obtained from the Microsoft Excel Statistics program, (Microsoft Corp., Redmond, WA.), and the SAS system PROC CORR procedure (SAS Institute, 2003), respectively.

Standard Calibration

The NH4+-N and NO3-N standards were processed in

the same way the samples are analyzed. The difference however, is that the electrode potential data is used for plotting a calibration curve, and to verify that the internal sensing slope is within the acceptable range of 57 to 63mv.

The standard curve is obtained using semilogarithmic graph paper, and plotting potential (mv.) on the linear axis vs. [NH4

+] on the log axis with the lowest concentration at the bottom of the scale. If the standards are accurately prepared, and the electrode is functioning properly a 10X change in concentration should produce a potential difference of about 59 mv. Another method for determining concentration is the following useful relationship.

[NH4+-N] = antilog [(E1 – Ex)/-S] Eq. [3]

where,

E1 = electrode potential of the 1.0 mg kg-1 standard

Ex = electrode potential of the unknown sample concentration

S = slope of electrode


Theory of Operation

The NH3 electrode detects [NO3-] only by first reducing it

to [NH4+]. TiCl3 is capable of chemically reducing up to 20

mg kg-1 of [NO3-] to [NH4

+] at the electrode. This reaction can be expressed as;

NO3- + 8Ti+3 + 10 H+ → NH4

+ + 8Ti +4 + 3H2O Eq. [4]

According to the above reaction, nitrate is chemically reduced at the expense of trivalent titanium that is oxidized to tetravalent titanium.

The second reaction at the electrode is the conversion of [NH4

+] to gaseous ammonia at pH = 12, which diffuses through a gas-permeable membrane until equilibrium is reached between the sample and the internal partial pressure of NH3. This is described by the relationship of Henry’s Law Constant (Maron, 1965);

[NH3] dissolved = Kh [pNH3] Eq. [5]

Where,

Kh = Henry’s Law Constant

At this point, the ammonia gas is detected at the electrode and converted to a concentration that is proportional to [NH4

+] in solution.

Materials

All samples were analyzed for NH3 and NO3- using an

NH3 gas sensing ion specific electrode, model 476130 (Corning Glass Works, Medfield, MA), and a pH/mv meter, model 320 (Orion Research, Beverly, MA.).

RESULTS AND DISCUSSION

Recovery Data

Table 1 shows an overall NO3- recovery range of 73-105 % for the three groups. Two samples from each group had NO3

- spikes greater than 12 mg kg-1. The remaining 18 samples were spiked with 10 mg kg-1 of NO3

- or less.

Those 18 samples showed very acceptable recoveries of approximately 96%.

The poor recovery observed for the two samples with high NO3

- spikes was unexpected since the old method states a maximum detectable NO3

- of 20 mg kg-1. Some accuracy was compromised at the high NO3

- end, perhaps as a result of the new fill solution formulation. Data from the lower NO3

- spikes (12 mg kg-1 or less) indicates that the procedure is usable in matrices other than water and wastewater, such as soil extracts. On the other hand, if the recovery is out of range (greater than +/- 10 %) it would indicate that something is wrong with the procedure or the electrode. The recovery problems associated with the original method (Eaton, 1995) could have been related to a residue of AgCl that excessively coats the glass tip of the electrode. The purpose of the special fill solution in that

method is to provide adequate ionic strength and generate an AgCl precipitate from the reaction of NH4Cl and AgNO3. The function of the AgCl is to lightly coat the silver internal reference electrode forming Ag/AgCl which has a constant potential. The ion product, (Q), (Brown, 1988) of the reaction between NH4Cl and AgNO3 is 3x10-2.

Table 1. Various additions of NO3-N (mg kg-1) to samples containing 5.0 mg NH4

+-N kg-1

Sample (Type/No.) NO3-N added NO3-N found Recovery, %

Soil Extract 1 0.60 0.63 105.0* 2 1.20 1.10 92.0 3 17.00 12.4 73.0 4 6.50 6.61 98.3 5 8.1 7.80 96.3 6 10.5 9.7 92.4 7 12.3 9.7 78.9 8 0.75 0.7 93.3 9 2.5 2.65 94.3 10 4.2 4.0 95.2

Avg. 91.0 Percolated Water 11 0.8 0.78 97.5 12 2.0 1.96 98.0 13 15.1 11.8 78.1 14 9.2 9.7 94.8 15 11.5 11.0 95.6 16 20.0 15.2 76.0 17 12.0 12.8 93.7 18 0.51 0.54 105.0* 19 7.5 8.0 93.7 20 10.0 9.6 96.0

Avg. 92.8 Deionized Water 1 9.5 9.9 104.2* 2 1.0 0.93 93.0 3 15.5 11.4 73.5 4 17.3 12.6 73.0

Avg. 85.9 * Recoveries greater than 100% are due to analytical tolerances. Acceptable recoveries are within a range of 90 to 105%. ** The un-spiked sample with 1.0 mg. kg-1 was previously subtracted from all samples.

The preparation of the fill solution was adjusted so that Q is now 1.3x10-2, and the ionic strength remains unchanged. While AgCl is still produced, the residue and cloudiness associated with it is less intense, and does not coat the glass tip as quickly. To further avoid any coating from the AgCl residue, the fill solution is changed every 20 to 30 samples. During these changes, it was observed that the glass tip of the electrode required less washing and cleaning.

The new fill solution probably enables the electrode to have greater nitrate accuracy between 0 to 10 mg kg-1, while forfeiting a greater range (0 to 20 mg kg-1).

Method Comparison

Nitrate concentrations of the 45 samples determined by the automated procedure and from the new NH3 electrode method are compared in Figure 1.


02468

1012141618

0 5 10 15

NO3-N mg kg-1 (Ammonia electrode)

NO 3-

N m

g kg

-1

(Aut

omat

ed P

roce

dure

)

Figure 1. Comparison of methods for nitrate analysis between ammonia electrode and an automated procedure. (r = 0.983) (Samples were soil extracts and percolate water)

The samples were chosen randomly, and were in the range of 0.2 to 15.4 mg NO3-N kg-1. The data compares very well and shows an overall correlation of r = 0.99. The scatter between the two methods is quite low, however where the nitrates are higher (more than 11 mg kg-1) the scatter between the two methods becomes greater. For example, below 11 mg NO3-N kg-1 agreement between the two methods is ~ 95%, whereas if the NO3

- is higher, it falls to ~78%. This may not be very significant since an acceptable working range of 0.5 to 10.0 mg NO3-N kg-1 still exists.

Replicate data

Table 2 shows the data of the two samples from the new and old methods that were replicated six times. The calculated means for the new method are 0.55 and 1.02 mg NO3-N kg-1 respectively for samples 1 and 2. These values closely represent the true concentrations of those samples, and therefore should be considered as the reference point for accuracy. The standard deviations (SD) for the two methods are dramatically different. The new method exhibited small (SD) values while higher (SD) values were common for the old method. Although the statistical means for the latter is marginal, the scatter between each replication is large. This shows poor reproducibility and precision. By comparison, the mean values for the new method are almost equal to the actual nitrate concentration, demonstrating excellent reproducibility and accuracy. Finally, as can be seen from this data, the old ammonia electrode method is of limited use at the nitrate level of less than1.0mg kg-1.

Table 2. Replication of samples with low nitrate concentrations. Trials Sample 1 2 3 4 5 6 Avg. SD

------------------- NO3- -N mg kg-1 -----------------------------

New Electrode Method (Revised) 1 0.3 0.3 0.8 0.8 0.7 0.4 0.55 0.24 2 1.1 0.8 1.3 1.0 1.1 0.8 1.02 0.19 Original Electrode Method (Provisional) 1 1.1 1.0 0.1 0.9 1.4 0.1 0.77 0.54 2 0.4 0.5 1.7 1.3 1.8 0.4 1.02 0.66 [NO3

- -N] Sample 1 = 0.5 mg kg-1 Sample 2 = 1.0 mg kg-1

CONCLUSIONS

It has been shown that by re-formulating the electrode fill solution the NH3 ISE is capable of performing quality NO3

- analysis. The operating range of the electrode is between 0.5 to 10.0 mg NO3-N kg-1. It was also shown that within this range of concentration, NO3

- results from the NH3 ISE are comparable to those from an automated procedure. Finally, the NH3 electrode was shown to have the capability of 90-100% analytical recovery when spiked with known NO3

- additions.

Since there are no interferences, the new NH3 electrode procedure can be used in matrices of soil extracts that have high chloride concentrations. The new electrode procedure is inexpensive and, NO3

- analysis can be performed for about 30 cents/sample.

REFERENCES

Braunstein, L., K.Hochmuller, and K.Spengler, 1980. Combined ammonia and nitrate analysis using an ion specific electrode. Special printing from Vom Wasser, 54.

Brown, T. and H.E. LeMay Jr., 1988, Chemistry, The Central Science. 4th ed. p.605, Prentiss Hall, Englewood Cliffs, N.J.

DeDatta, S., 1987. Principles and practice of rice production. R.E. Krieger Pub. Co., Malabar, FL.

Eaton, A., A. Cleseri, and A. Greenberg, (Ed). 1995. Standard methods for the examination of water and wastewater. 19th ed. American Public Health Assoc., American Water Works Assoc. and Water Environment Federation. Washington, D.C.

Maron, S and C.F. Prutton, 1965, Principles of Physical Chemistry. 4th ed. pg. 296-297, Macmillan Co., N.Y.

SAS Institute, 2003. Ver. 9.0 SAS, Cary, N.C.

DEDICATION OF THE SIXTY-FIFTH PROCEEDINGS SOIL AND CROP SCIENCE SOCIETY OF FLORIDA

Brian L. McNeal

Brian L. McNeal

Dr. Brian L. McNeal is a native of central Oregon. He was educated at Oregon State University and the University of California-Riverside where he received his Ph.D. degree in soil chemistry. He spent 10 years as a research soil scientist for the U.S. Salinity Laboratory of the United States Department of Agriculture and 13 years as a professor of Soil Chemistry at Washington State University. His early career dealt with effects of salinity on soils and plants, with particular emphasis on the effects of solution composition and concentration on soil hydraulic properties. During his years in Washington his research emphases shifted to losses of nutrients and sediments from agricultural lands, along with some work on forested ecosystems.

He joined the University of Florida-Gainesville in 1983 where he served as Chair of the Soil and Water Science Department until 1990. While at Florida his research focused on nutrient-loss studies from vegetable and citrus fields in central Florida, which included managing a large demonstration project in Manatee County that helped to establish nitrate-N accumulation patterns beneath vegetable fields and citrus groves of the area. He also did some collaborative work on the development of a tomato growth model and studies of rooting patterns for vegetables and citrus. He served as

director of the University of Florida’s Center for Natural Resources during the mid-1990s and for several years as the University of Florida/Institute of Food and Agricultural Sciences liaison to the Florida Department of Agriculture and Consumer Services for the state Legislature’s Nitrate Bill which was designed to develop research-based Better Management Practices for croplands of the state.

He has served as President of the Western Society of Soil Science, and as chair of the Soil Chemistry Division (S-2) of the Soil Science Society of America. He is a Fellow of the American Society of Agronomy and the Soil Science Society of America. He also served as editor of the Soil and Crop Science Society of Florida Proceedings from 1994 to 1998.

Dr. McNeal enjoyed teaching and frequently taught graduate-level courses in soil and water chemistry both at the University of Florida and at Washington State University. He was also heavily involved in the under-graduate “General Soils” course while at UF. He has written over 100 scientific publications including textbooks translated into Spanish, Chinese, Russian and Hungarian.

He and his wife Dee Ann moved to Utah in 2001 to be closer to family, and he fully retired from UF in 2003.


Effect of Irrigation and Gypsum Application on Aflatoxin Accumulation in Peanuts

P. J. Wiatrak, D. L. Wright, J. J. Marois, and D. Wilson

ABSTRACT

Aflatoxin accumulation in peanuts (Arachis hypogaea L.) is generally associated with drought conditions. The objective of this study, conducted in 2001 and 2002, was to evaluate the influence of two irrigation treatments (not irrigated and irrigated), and two gypsum applications (0 and 560 kg ha-1) on aflatoxin accumulation in two peanut cultivars (Georgia Green and C-99R). Aflatoxin accumulation in peanuts was less for Georgia Green than C-99R in 2002 (12.0 and 37.7 ng g-1, respectively) while no difference was observed between cultivars in 2001. Also, aflatoxin in peanuts was positively correlated with air temperature at 1, 3, and 4 wk prior to harvest (r=0.21, r=0.22, and r=0.28, respectively), soil temperature at 1, 3, 4, and 5 wk prior to harvest (r=0.22, r=0.22, r=0.24, and r=0.29, respectively), and precipitation at 2 wk prior to harvest (r=0.29). A negative correlation of aflatoxin was noted with precipitation at 3 wk prior to harvest (r=-0.31). Aflatoxin accumulation was not correlated with peanut yields; however, it was greater with higher percentage of total kernel damage (r=0.24). The results of this study indicate that higher air and soil temperatures increase aflatoxin accumulation in peanuts.

INTRODUCTION

Drought and high temperatures are conducive to A. flavus infection and aflatoxin contamination (Guo et al., 2003). During drought years the infected crops increase aflatoxigenic fungi in soil (Horn, 2003); therefore resulting in high contamination level of aflatoxins in peanuts (Barros et al., 2003) and lower peanut yields (Chiou et al., 1999).

The soil serves as a reservoir for A. flavus fungi that produce carcinogenic aflatoxins in agricultural commodities (Horn, 2003). Most of the Aspergillus species are soil borne facultative saprophytes but some are capable of causing decay in storage, disease in plants, or invasive disease in humans and animals (Wilson et al., 2002). Horn (2003) reported that aflatoxigenic fungi reside in soil as conidia, sclerotia, and hyphae, which act as primary inoculants for directly infecting peanuts. Aspergillus flavus, A. niger, and other aspergilli produce mycotoxins that include aflatoxins and ochratoxins, as well as cyclopiazonic acid, patulin, sterigmatocystin, gliotoxin, citrinin, and other potentially toxic metabolites (Wilson et al., 2002). Aflatoxin contamination in the field is known to be influenced by numerous factors (Guo et al., 2003).

Aspergillus flavus was dominant species isolated in soil during the planting and harvest periods of peanut (Barros et al., 2003). Higher frequencies of toxigenic A. flavus in the soil results in high contamination level of aflatoxins in peanut seeds (Barros et al., 2003), and aflatoxin concentrations were significantly correlated with A. flavus group populations in both shells and seed (Brenneman et al, 1993). Barros et al. (2003) noted that Aspergillus species showed no significant differences in accumulation between planting and harvest time in two out of three evaluated regions and differences in the ratio of toxigenic and atoxigenic strains dependent on the period and the region evaluated.

Calcium is important for adequate kernel development (Gascho and Davis, 1995). Therefore, gypsum is applied at flowering of peanut to insure adequate availability of Ca in the fruiting zone (0- to 8-cm soil depth) during pod development (Alva et al., 1990). The purpose of the study was to evaluate the influence of irrigation and gypsum application on aflatoxin contamination in C-99R and Georgia Green peanuts.


Field trials with Georgia Green and C-99R peanuts were conducted in 2001 and 2002 on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults) at the Univ. of Florida, North Florida Res. and Ed. Ctr., Quincy, FL.

The experimental area, following winter fallow, was sprayed with glyphosate [N-(phosphonomethyl) glycine] at 0.7 kg a.i. ha-1 + 2,4-D (2,4-dichlorophenoxyacetic acid) at 0.55 kg a.i. ha-1 on 24 April 2001 and glyphosate at 1.4 kg a.i. ha-1 on 18 and 26 March 2002. The treatments consisted of peanut cultivars (Georgia Green and C-99R), irrigation (no irrigation and irrigation), and gypsum applications (0 and 560 kg ha-1). Prior to planting peanuts in strip-till, the rows were ripped with a Brown strip-till implement (Brown Manufacturing Co., Ozark, AL). Georgia Green and C-99R cultivars were planted using a Monosem air planter (A.T.I. Inc., Lenexa, KS) at 4 seeds per 0.3 m of row on 25 May and 10 April in 2001 and 2002, respectively. Each plot was 9.1-m long and consisted of six rows (5.5-m wide) with 0.91-m row spacing. P. J. Wiatrak and D. L. Wright, Agronomy Dep.; J. J. Marois, Pathology

Dep., Univ. of Florida, North Florida Res. and Educ. Center, Quincy, FL 32351; and D. Wilson, Dep. of Plant Pathol., Univ. of Georgia, 109 Plant Science Drive, Tifton, GA 31793. This research was supported by the Florida Agric. Exp. Stn.

*Corresponding author ( [email protected] ). Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:5-8 (2006).

The study was treated with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine) at 0.9 kg a.i. ha-1 after planting (pre-emergence) to control weeds. Gypsum was surface-applied on treatments with gypsum at first bloom. Approximately 40 days after emergence, imazapic (2-[4,5-dihydro-4-methyl-4-(1-



methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid) was applied at 70.6 gms a.i. ha-1. The early (Cercospora arachidicolla S. Hori) and late [Cercosperidium personatum (Berk. & M.A. Curtis) Deighton] leaf spot diseases were controlled with chlorothalonil (tetrachloroisophthalonitrile) at 0.9 kg a.i. ha-1 applied every two weeks beginning 40 days after planting. The irrigation sections were irrigated (as needed) at 15.2 mm on 6 and 18 July, 3, 23, and 28 Aug., and 21 Sep. 2001, and 30 May, 6, 14, and 21 June, 5 and 18 July, and 9 and 29 Aug. 2002. The irrigation was performed using a lateral-move sprinkler system with ON/OFF nozzles.

Soil samples for A. flavus and A. niger analysis were collected prior to digging peanuts. Soil probes were used to collect 10 cores of soil at 15-cm depth from two middle rows. These samples were mixed thoroughly and a 5-g sample was suspended in 100 ml of 0.2% water agar. Aliquots (1 ml) of this suspension were pipetted onto each of 5 Petri dishes (6-cm diameter) containing M3S1B, a selective A. flavus group and A. niger group isolation medium (Griffin and Garren, 1974). The suspension was spread evenly over the agar surface and the plates were incubated at 30oC. Colonies were counted after 7 d of incubation and the results were recorded as propagules of A. flavus and A. niger group fungi per g of soil.

Georgia Green peanuts were dug on 16 Oct. 2001 and 3 Sep. 2002, and picked 2 to 3 d later. The C-99R cultivar was dug and picked 1 wk later than Georgia Green peanuts due to later C-99R maturity. The peanut sample (2 kg) from each plot was mechanically shelled and the seeds chopped to obtain a uniform mixture. Aflatoxins were determined in a 50-g subsample. According to the method described by Thean et al. (1980), after aqueous methanol extraction, ammonium sulfate treatment, and partition of aflatoxins into chloroform, sample extracts were purified. These extracts were analyzed by high-performance chromatography with postcolumn iodine derivatization as described by Beaver et al. (1990).

Weather data were collected near the test sites from a weather station located at the North Florida Res. Ed. Ctr., Quincy, FL (84˚ 33' W, 30˚ 36' N). The monthly air temperatures and rainfall with 20-year average and sum, respectively, during the two growing seasons are shown in

Table 1. Compared to multiyear averages, air temperatures were 1.3, 0.1, and 1.8oC lower in July, August, and September of 2001, respectively. In 2002, air temperatures were 0.8 and 0.9oC higher in May and September, respectively. Rainfall was generally lower during the 2-year vegetation periods compared to the 20-year average, except higher precipitation in March, June, and September of 2001 (252, 310, and 194 mm, respectively), and September of 2002 (223 mm).

The experimental design was a randomized complete block in a split-split plot treatment arrangement with four replications. The main effects were cultivars, sub-plots were irrigation treatments, and sub-sub plots were gypsum applications. Data were analyzed using the general linear models (SAS, 1989), and means were separated using Fisher's Protected Least Significant Difference Test (P≤0.05). The Pearson correlation coefficient of aflatoxin was evaluated with the average air and soil temperatures, and total precipitation from 1 to 5 wk prior to harvest peanuts using proc corr (SAS, 1989).


There was an irrigation x gypsum interaction for A. flavus concentration (Table 2). The A. flavus concentration in the soil decreased with gypsum application on the treatment with no irrigation, while no difference was observed between gypsum applications on irrigated treatments (Table 3). Cultivar did not influence the A. flavus concentration in the soil (Table 2). An interaction of year x irrigation x gypsum was observed for A. niger in the soil. In 2002, gypsum application increased A. niger concentration on the treatment without irrigation, while this concentration was not influenced by gypsum application on irrigated treatments. An irrigation x gypsum application interaction was not significant in 2001. The A. niger concentration, averaged across years, was 85% lower with irrigation treatment than without (Table 2). Peanut cultivar did not influence A. niger concentration in the soil. Horn (2003) noted that population of fungi in soil is genetically diverse and individual genotypes show a clustered distribution pattern within fields. Our results disagree with Brenneman et al. (1993) who noted that irrigation had no effect on soil populations of A. niger and variable effects on A. flavus populations. Generally, the results indicate that the population of A. flavus in the soil

Table 1. Average air temperature and precipitation at Quincy, FL during the growing seasons of 2001 and 2002. Air temperature Precipitation

Month 2001 2002 20-year avg. 2001 2002 20-year avg. -------------------- oC --------------------- -------------------- mm -------------------

March 14.3 15.6 15.6 252 58 167 April 19.9 22.0 18.5 30 35 106 May 22.7 23.6 22.8 28 77 122 June 26.0 26.2 25.8 310 109 154 July 25.8 27.2 27.1 133 140 167 Aug. 25.8 26.9 26.7 142 61 149 Sept. 24.1 25.9 25.0 194 223 101

Avg. / Total 22.7 23.9 23.1 1089 703 966


Table 2. Analysis of variances (ANOVA) with cultivar, irrigation, and gypsum influence on Aspergillus flavus and Aspergillus niger in the soil, and peanut aflatoxin accumulation at Quincy, FL in 2001 and 2002.

Table 3. Interactions of year x irrigation x gypsum application for Aspergillus niger, irrigation x gypsum application for Aspergillus flavus in the soil, and year x cultivar for aflatoxin accumulation in peanuts at Quincy, FL.

2001 2002 Characteristic No irrigation Irrigation No irrigation Irrigation

A. nigerGypsum, kg ha-1 ----------------------------------- no. propagules g-1 ---------------------------------

0 51 a† 47 a 326 b 125 a 560 42 a 27 a 1417 a 75 a

No irrigation Irrigation

A. flavus Gypsum, kg ha-1 ---------- no. propagules g-1 -----------

0 89 a 33 a 560 32 b 62 a

2001 2002 Aflatoxin Cultivar ------------------- ng g-1 -----------------

C-99R 0.4 a 37.4 a Georgia Green 19.2 a 12.0 b

† Means in column followed by the same letter are not different at P > 0.05.

can be reduced by gypsum application in non irrigated fields. However, the population of A. niger varies across years and may be less without gypsum application in non irrigated fields.

An interaction of year x cultivar was found for aflatoxin concentration (Table 2). Aflatoxin concentration was less in the presence of Georgia Green than C-99R peanuts in 2002 (Table 3) possibly due to lower number of damaged kernels found in Georgia Green. No significant (P≤0.05) difference was observed between cultivars for aflatoxin accumulation in 2001 (Table 3). Aflatoxin

concentration was not influenced by irrigation and gypsum applications.

Aflatoxin accumulation in peanuts was positively correlated with air temperature at 1, 3, and 4 wk prior to harvest, soil temperature at 1, 3, 4, and 5 wk prior to harvest, and precipitation at 2 wk prior to harvest (Table 4). However, a negative correlation of aflatoxin was noted with precipitation at 3 wk prior to harvest. Horn (2003) found that climate influences species density and aflatoxin-producing potential. During drought years, the infected crops increase aflatoxigenic fungi in soil (Horn, 2003); therefore resulting in high contamination level of

Characteristic A. flavus A. niger Aflatoxin --------------------- no. propag. g-1 -------------------- ------- ng g-1 ------- Cultivar (C)

C-99R 61 a† 411 a 17.4 a Georgia Green 47 a 116 a 15.6 a

Irrigation (I)

No 60 a 459 a 14.0 a Yes 47 a 68 b 18.9 a

Gypsum (G), kg ha-1

0 61 a 137 a 13.4 a 560 47 a 390 a 19.5 a

ANOVA

Year (Y) NS ** NS C NS NS NS Y x C NS NS ** I NS * NS Y x I NS ** NS C x I NS NS NS Y x C x I NS NS NS G NS NS NS Y x G NS NS NS C x G NS NS NS I x G ** * NS Y x C x G NS NS NS C x I x G NS NS NS Y x I x G NS * NS Y x C x I x G NS NS NS

† Means in column followed by the same letter are not different at P > 0.05. *, **, Significant at P ≤ 0.05 and 0.01, respectively.


aflatoxins in peanut seeds (Barros et al., 2003). Guo et al. (2003) stated that drought and high temperatures are conducive to A. flavus infection and aflatoxin contamination. Chiou et al. (1999) reported that inoculation with A. niger alone or with A. flavus resulted in lower yields of peanut pods compared to non inoculated treatments. Generally, aflatoxin accumulation in peanuts is influenced by environmental conditions. Table 4. Pearson correlation coefficient of aflatoxin in peanuts with average air temperature, and precipitation at Quincy, FL in 2001 and 2002.

Characteristic Aflatoxin Air temperature (wk prior to harvest)

1 0.21* 2 0.18 3 0.22* 4 0.28** 5 0.19

Soil temperature (wk prior to harvest) 1 0.22* 2 0.19 3 0.22* 4 0.24* 5 0.29**

Precipitation (wk prior to harvest) 1 0.15 2 0.29** 3 -0.31** 4 0.20 5 -0.04

*, ** Significant at P ≤ 0.05 and 0.01, respectively.

CONCLUSIONS

Aspergillus flavus concentration in the soil decreased with gypsum application on the treatment without irrigation, while this concentration increased with gypsum application on the treatment with irrigation. Aspergillus niger concentration varied across years and increased with gypsum application on non irrigated fields in 2002. Aflatoxin concentration was less for Georgia Green than C-99R peanuts in 2002 while there was no difference between cultivars in 2001. Higher air and soil temperatures increased the aflatoxin accumulation.

REFERENCES

Alva, A.K., G.J. Gascho, and W.A. Cromer. 1990. Irrigation frequency-effects on leaching of cations from gypsum amended coastal-plain surface soils. Water Air Soil Pollut. 52:325-336.

Barros, G., A. Rorres, G. Palacio, and S. Chulze. 2003. Aspergillus species from section Flavi isolated from soil at planting and harvest time in peanut-growing regions of Argentina. J. Sci. Food Agric. 83:1303-1307.

Beaver, R.W., D.M. Wilson, M.W. Trucksess. 1990. Comparison of postcolumn derivatization-liquid chromatography with thin-layer chromatography for determination of aflatoxins in naturally contaminated corn. J. Assoc. Off. Anal. Chem. 73:579-581.

Brenneman, T.B., D.M. Wilson, and R.W. Beaver. 1993. Effects of diniconazole on aspergillus populations and aflatoxin formation in peanut under irrigated and nonirrigated conditions. Plant Dis. 77:608-612.

Chiou, R.Y., Y.Y. Wen, S. Ferng, and S.P. Learn. 1999. Mould infection and aflatoxin contamination of the peanut kernels harvested from spring and fall crops as affected by artificial inoculation of the seeded kernels with Aspergillus flavus and Aspergillus niger. J. Sci. Food Agric. 79:1417-1422.

Gascho, G.J., and J.G. Davis. 1995. Soil fertility and plant nutrition. p. 383–418. In H.E. Pattee and T.H. Stalker (ed.) Advances in peanut science. Am. Peanut Res. and Educ. Soc., Stillwater, OK.

Griffin, G.J., and K.H. Garren. 1974. Population levels of Aspergillus flavus and the A. niger group in Virginia peanut field soils. Phytopathol. 64:322-325.

Guo, B.Z., J. Yu, C.C. Holbrook, R.D. Lee, and R.E. Lynch. 2003. Application of differential display RT-PCR and EST/microarray technologies to the analysis of gene expression in response to drought stress and elimination of aflatoxin contamination in corn and peanut. J. Toxicol. - Toxin Rev. 22:287-312.

Horn, B.W. 2003. Ecology and population biology of aflatoxigenic fungi in soil. J. Toxicol. – Toxin Rev. 22:351-379.

Thean, J.E., Lorenz, D.R., Wilson, E.M., Rogers, K., and Gueldner, R.C. 1980. Extraction, cleanup and quantitative determination of aflatoxins in corn. J. Assoc. Off. Anal. Chem. 63:631-633.

SAS Institute. 1989. SAS user's guide. SAS Inst., Cary, NC.

Wilson, D.M., W. Mubatanhema, and Z. Jurjevic. 2002. Biology and ecology of mycotoxigenic aspergillus species as related to economic and health concerns. Mycotoxins Food Safety 504:3-17.


Biomass Yield and Forage Nutritive Value of Cynodon Grasses Harvested Monthly

P. Mislevy* and F. G. Martin

ABSTRACT

Perennial grasses are the major source of livestock nutrients in subtropical and tropical regions of the world. There is a need to constantly screen for new entries with improved yield, nutitive value, and increased cool season production. Five Cynodon grasses consisting of three bermudagrasses [Cynodon dactylon (L.) Pers., >Bermudagrass 2000' , >Jiggs=, >Tifton 85'] and two stargrasses (C. nlemfuesis Vanderyst var. nlemfuensis, >Florona= and >Stargrass 2000') were vegetatively planted in a RCB design with six replicates, during the fall of 2000. Grasses were harvested on a 28-d schedule during both the warm (15 April - 15 October) and cool (16 October - 14 April) season over a 3 yr period to determine dry biomass (DB) yield, crude protein (CP) and in vitro organic matter digestion (IVOMD). Data was summarized separately for both the warm and cool season of each year. Total annual DB yield of Bermudagrass 2000 and Jiggs bermudagrass (27.6 Mg ha-1) was generally greater (P<0.05) than Tifton 85 bermudagrass (26.3 Mg ha-1) and both stargrasses (24.1 Mg ha-1) when averaged over 3 yr. These three bermudagrasses consistently produced greater yields during the warm season than the stargrasses. However, during the cool season greatest yields were obtained from Bermudagrass 2000, Jiggs, and Florona stargrass compared with the other grasses. These three grasses averaged 10.2, 11.1, and 10.5 Mg ha-1, respectively or 37, 40, and 41% of their total annual yield was produced during the cool season. Average CP and IVOMD of these grasses was low (107 and 540 g kg-1 respectively) during the hot, wet summer (July - September). Nutritive value of these grasses during the cool season was good averaging 202 and 664 g kg-1 for CP and IVOMD, respectively. These data indicate Cynodon grasses can be very productive under a clipping program in central Florida when harvested on a 28-d schedule and well fertilized.

INTRODUCTION

Perennial grasses are extremely important to the Florida livestock industry. These grasses can be used for grazing, hay, or haylage and utilized by numerous classes of livestock. Before cultivars can be recommended they must be tested under edaphic conditions within a specific climatic region. Management variables (soil fertility, harvesting regime, stubble height, harvest frequency, etc.) must be evaluated to determine their influence on persistence, yield, and quality (Mislevy and Everett 1981; Mislevy et al.1990; Mislevy and Martin 1998). In recent years, efforts to increase beef production in subtropical Florida have centered around bermudagrass and stargrass cultivars. These grasses produce high warm season yield and good cool season-short day DB yields (Mislevy and Everett 1981; Sinclair et al., 2001). Cynodon grasses have demonstrated a high potential for cool season-frost free (late fall and early spring) forage production and good

animal performance during the warm season (Mislevy and Everett 1981; Mislevy et al., 1989; Mislevy et al., 1995; Sinclair et al., 2001).

The purpose of this clipping experiment was to determine the DB and nutritive value of experimental Cynodon entries compared to available standards when harvested during the warm and cool seasons over a 3-yr period.


The grasses were established in September 2000 (except Stargrass 2000 which was planted in November 2000) on a Pomona fine sand (sandy, siliceous, hyperthermic Ultic Alaquod) and conducted from 2001 to 2004 at the Range Cattle Research and Education Center, Ona, Florida. A total of five Cynodon grasses consisting of three bermudagrasses (Bermudagrass 2000, Jiggs, and Tifton 85) and two stargrasses (Florona and stargrass 2000) were planted on 0.5-m centers from rooted crowns.

The field plot layout was a RCB design with six replicates with plots measuring 1.8 by 3.7 m. When plants showed signs of vegetative growth, 56-15-56 kg ha-1 N-P-K plus 1.7 kg ha-1 Zn, Cu, Mn, and Fe (sulfate form); 3.4 kg ha-1 S; and 0.17 kg ha-1 B was applied. This was followed by a second 56 kg N ha-1 application 35 d after planting. Soil pH, Ca, and Mg averaged 5.4, 702, and 160 Mg ha-1, respectively. The fertilization program during the 3-yr harvest period consisted of 56-10-37 kg ha-1 N-P-K plus 1.1 kg ha-1 Cu, Zn, Mn, and Fe (sulfate form), 0.11 kg ha-1 B and 2.3 kg ha-1 S prior to initial (April 2001) and following each harvest.

A 0.5 by 2.5 m strip of forage was harvested on a 4-wk schedule over a 3-yr period, with the exception of January 2002 and December 2003, when top growth was killed by a freeze. Crude protein and IVOMD of harvested forage was determined for selected harvests during the warm and cool seasons. All forage samples were dried at 60 C, ground, and analyzed for total N (Gallaher et al., 1975; Hambleton, 1977). Crude protein concentration was calculated as 6.25 X N. In vitro organic matter digestion was determined for forage samples by the two-stage procedures of Tilley and Terry (1963) modified by Moore and Mott (1974). Statistical analyses consisted of a simple entry comparison using six randomized complete blocks. The pooled year analyses revealed a significant P<0.05 year x entry interaction. Analysis was performed on each harvest and total DB for each year and on a pooled year analyses for total DB using a PROC GLM (SAS, 1989).

P Mislevy, Range Cattle Res. and Educ. Center, Ona, FL 33865-9706; F. G. Martin, Statistics Dep., Univ. of Florida, Gainesville, FL 32611-0840. This research was supported by the Florida Agric. Exp. Stn.




Table 1. Dry biomass yield of Cynodon grasses harvested on a 28 d schedule during the warm (April 15 - Oct. 15) and cool (Oct. 16 – April 14) season of 2001-2002.

Harvest Date Grass 6 June 4 July 1 Aug 29 Aug 25 Sept Total ------------------------------------------------------------- Mg ha-1 --------------------------------------------------------------------------------------- Bermudagrass Warm Season 2000 3.1 aH 8.3 a 2.8 a 3.1 a 2.4 a 19.7 Jiggs 2.9 a 8.1 a 2.5 ab 2.4 b 2.3 ab 18.2 Tifton 85 3.7 a 7.3 b 2.3 b 2.0 c 2.0 c 17.3 Stargrass Florona 2.8 a 5.9 c 2.4 ab 2.1 c 2.1 bc 15.3

Grass 24 Oct 20 Nov 20 Dec 13 Feb 3 Mar 9 Apr Total ------------------------------------------------------------- Mg ha-1 --------------------------------------------------------------------------------------- Bermudagrass Cool Season 2000 2.1 a 1.6 a 2.6 a 1.8 a 0.9 a 3.6 ab 12.6 Jiggs 2.0 a 1.3 b 2.5 ab 1.6 a 1.0 a 3.6 ab 12.0 Tifton 85 1.7 b 1.1 bc 2.2 b 1.1 b 0.6 b 3.3 b 10.0 Stargrass Florona 1.5 c 1.0 c 2.4 ab 1.1 b 0.8 b 4.3 a 11.1 H Means within the column followed by the same letter(s) during the warm and cool seasons are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

Significant differences were investigated using the Waller-Duncan mean separation procedure.


Dry biomass yields, CP concentration, and IVOMD content will be presented for harvests taken during the warm (15 April – 15 October) and cool (16 October – 14 April) seasons 2001 to 2004. With few exceptions, differences (P<0.05) were found between grass entries for most harvests during both the warm and cool seasons. During the warm season of 2001 no difference in DB yield for the initial harvest (6 June) was obtained (Table 1). However, Bermudagrass 2000 produced higher (P<0.05) yields than Tifton 85 for the next four harvests of the warm season, yielding a total of 19.7 Mg ha-1, compared with 17.3 and 15.3 Mg ha-1 for Tifton 85 and Florona stargrass, respectively.

Continuously harvesting these grasses during the cool season of 2001-02, revealed differences (P<0.05) between entries for all six harvests (Table 1). Bermudagrass 2000 continued to produce more DB yield than Tifton 85 throughout the cool season producing a total of 12.6 Mg ha-1 compared with 10.0 Mg ha-1 for Tifton 85. Yields were not different between Bermudagrass 2000 and Jiggs for five of the six cool season harvests. Both Bermudagrass 2000 and Jiggs were generally more productive than Florona during the winter. However, as spring approached (9 April) with increased daylength and warmer temperatures, Florona showed increased production compared to the other cool season harvests.

At the beginning of the warm season of 2002, Stargrass 2000, which was planted later than the other entries, came into production and was compared with the other four entries (Table 2). Dry biomass yields were not

different between entries for the May and June harvests, however, differences (P<0.05) did exist between the remaining four harvests. Forage production during the warm season of 2002 was similar to 2001 for Bermudagrass 2000 and Jiggs averaging 19.5 and 18.8 Mg ha-1, respectively. Yields for Tifton 85 and Florona increased about 15% from the previous warm season. Total forage production during the cool season of 2002-03 remained the same for Jiggs averaging 12.2 Mg ha-1, however, Bermudagrass 2000 decreased 15% and Tifton 85 increased 15% from the previous year. The overall average between the three bermudagrasses and Florona stargrass was about the same (11.5 Mg ha-1; Table 2).

Dry biomass yields for the third harvest year (warm season 2003) were about 30% lower when compared with the first and second warm season (2001 and 2002) yields. Similar yield reductions after the second harvest year were reported by Mislevy et al. (1996) and Mislevy et al. (2005) for Paspalum, Brachiaria and Setaria grasses. Yield reductions for the cool season of 2003-04 (Table 3) were also 30% lower than the previous two years. Jiggs, Florona, and Bermudagrass 2000 were the highest yielding entries averaging 9.2, 8.4, and 7.3 Mg ha-1, respectively.

Stargrass 2000 produced good yields over a 2-yr period, however, it was never among the highest yielding entries. Additionally, this stargrass is a large robust entry with an open canopy. Because of the open canopy, weed invasion is also a problem with this new stargrass.

Total annual yield over 3 yr is presented in Table 4. Bermudagrass 2000 and Jiggs both produced the highest yield averaging 27.6 Mg ha-1 yr-1, with Tifton 85 and Florona averaging 26.3 and 25.9 Mg ha-1, respectively. After 34 harvests over 3 yr, average total yield did not vary by more than 6% between Florona and the three bermudagrasses.


Table 2. Dry biomass yield of Cynodon grasses harvested on a 28 d schedule during the warm (April 15 – Oct. 15) and cool (Oct. 16 – April 14) season of 2002-2003.

Harvest Date Grass 9 May 6 June 2 July 30 July 27 Aug 24 Sept Total ------------------------------------------------------- Mg ha-1 ----------------------------------------------------------------------------- Bermudagrass Warm Season 2000 4.7 aH 3.1 a 4.3 ab 2.0 a 3.3 a 2.1 a 19.5 Jiggs 4.8 a 3.3 a 4.0 bc 1.6 b 3.4 a 1.7 b 18.8 Tifton 85 5.0 a 3.6 a 4.6 a 2.0 a 3.1 a 1.7 b 20.0 Stargrass Florona 4.3 a 3.3 a 4.0 bc 1.6 b 3.1 1.5 b 17.8 2000 4.4 a 3.3 a 3.7 c 1.1 c 2.5 b 1.0 c 16.0

Grass 22 Oct 21 Nov 18 Dec 17 Jan 13 Feb 18 Mar 14 Apr Total ------------------------------------------------------- Mg ha-1 ----------------------------------------------------------------------------- Cool Season Bermudagrass 2000 2.8 ab 2.0 b 0.4 ab 0.3 a 0.4 a 4.3 b 0.5 b 10.7 Jiggs 2.9 a 2.3 a 0.4 ab 0.3 a 0.4 a 5.0 a 0.9 a 12.2 Tifton 85 2.3 c 1.8 bc 0.5 a 0.1 c 0.2 b 5.6 a 1.0 a 11.5 Stargrass Florona 2.5 bc 2.4 a 0.4 ab 0.2 b 0.4 a 5.3 a 0.8 a 12.0 2000 1.8 d 1.7 c 0.3 b 0.2 b 0.2 b 5.8 a 0.5 b 10.5 H Means within the column followed by the same letter(s) during the warm and cool seasons are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

Table 3. Dry biomass yield of Cynodon grasses harvested on a 28 d schedule during the warm (April 15 – Oct. 15) and cool (Oct. 16 – April 14) season of 2003-2004.

Harvest Date Grass 9 May 5 June 1 July 30 July 26 Aug 23 Sept Total ------------------------------------------------------------- Mg ha-1 --------------------------------------------------------------------------------------- Bermudagrass Warm Season 2000 3.7 aH 2.3 c 2.4 a 2.7 a 1.2 a 0.9 a 13.2 Jiggs 3.3 ab 1.8 d 2.2 a 2.6 a 1.1 a 0.8 a 11.8 Tifton 85 2.8 c 3.7 a 2.4 a 2.1 b 1.4 a 0.8 a 13.2 Stargrass Florona 2.9 bc 3.4 ab 2.3 a 2.7 a 1.0 a 1.0 a 13.3 2000 2.8 c 3.3 b 2.2 a 2.1 b 1.1 a 0.2 b 11.7

Grass 23 Oct 19 Nov 4 Jan 11 Feb 10 Mar 7 Apr Total ------------------------------------------------------------- Mg ha-1 --------------------------------------------------------------------------------------- Bermudagrass Cool Season 2000 0.9 b 1.6 ab 1.3 a 0.3 a 1.5 c 1.7 b 7.3 Jiggs 1.0 ab 1.9 a 1.4 a 0.3 a 2.2 a 2.4 a 9.2 Tifton 85 1.0 ab 1.9 a 0.9 b 0.3 a 1.4 c 1.0 c 6.5 Stargrass Florona 1.2 a 1.9 a 1.2 a 0.3 a 1.9 b 1.9 b 8.4 2000 0.6 c 1.4 b 0.9 b 0.4 a 1.5 c 1.6 b 6.4 H Means within the column followed by the same letter(s) during the warm and cool seasons are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

Table 4. Total annual yield of Cynodon grasses harvested over a 3-yr period.

Year Grass 2001-2002 2002-2003 2003-2004 ---------------------------- Mg ha-1 -------------------------- Bermudagrass2000 32.0 aH 30.3 a 20.4 ab Jiggs 30.7 a 31.0 a 21.0 ab Tifton 85 27.3 b 31.6 a 19.9 b StargrassFlorona 26.4 c 29.7 a 21.6 a 2000 --- 26.5 b 18.3 c Avg 29.1 29.8 20.2 H Means within the column followed by the same letter(s) are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

Total warm seasonal yield summarized over 3 yr averaged 17.5, 16.8, 16.3, and 15.5 Mg ha -1 for Bermudagrass 2000, Tifton 85, and Jiggs bermudagrass and Florona stargrass, respectively (data not shown). There was only a 1.3 Mg ha-1 difference between the average of three bermudagrasses and Florona stargrass. Data summarized over 3 yr for the cool season revealed Jiggs, Florona, and Bermudagrass 2000 averaged 11.1, 10.5, and 10.2 Mg ha-1, respectively. Tifton 85 was one of the lowest yielding grasses during the cool season averaging 9.3 Mg ha-1. Studies by Sinclair et al (2001) showed Tifton 85 was sensitive to short days, and increased in dry biomass yield


Table 5. Crude protein (CP) concentration and in vitro organic matter digestion (IVOMD) of Cynodon grasses harvested during the warm (April 15 – Oct. 15) and cool (Oct. 16 – April 14) season of 2001 - 2002.

CP IVOMD Grass 6 June 1 Aug 29 Aug 25 Sept 6 June 1 Aug 29 Aug 25 Sept ----------------------------------------------------------------------------- g kg-1 ---------------------------------------------------------------------------- Bermudagrass Warm Season2000 211 aH 119 a 84 a 107 a 625 c 557 ab 520 bc 533 b Jiggs 226 a 113 a 90 a 107 a 631 bc 552 b 529 b 534 b Tifton 85 219 a 120 a 95 a 103 a 659 a 573 a 556 a 555 a Stargrass Florona 230 a 112 a 89 a 101 a 652 ab 541 b 506 c 514 c Avg 222 116 90 105 642 556 528 534

Grass 20 Nov 13 Mar 20 Nov 13 Mar ----------------------------------------------------------------------------- g kg-1 ---------------------------------------------------------------------------- Bermudagrass Cool Season2000 211 ab 219 a 647 b 702 a Jiggs 204 a 218 a 644 b 670 b Tifton 85 220 ab 222 a 663 ab 697 ab Stargrass Florona 232 a 212 a 678 a 697 ab Avg 217 218 658 692 H Means within the column followed by the same letter(s) during the warm and cool seasons are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

2 to 4 fold when photoperiod was extended by supplemental lighting.

Forage Nutritive Value

No difference was found in CP concentration between grass entries harvested during the warm season of 2001 (Table 5). Average CP concentration in grasses for the 6 June sampling was 222 g kg-1 which then dropped 48% to 116 g kg-1 by 1 August sampling. Crude protein continued to drop an additional 22% at the 29 August sampling date followed by an increase of 17% by 25 September.

The IVOMD content during the warm season of 2001 was generally highest (P<0.05) for Tifton 85 bermudagrass and lowest for Florona stargrass. It followed a similar pattern to CP during the summer months decreasing by 13% from 642 to 556 between June and 1 August. The IVOMD continued to drop an additional 5% between 1 August and 29 August, followed by a 1% increase by 25 September. This forage nutritive slump during the summer months with saturated soil and high temperature has been observed in numerous studies (Prates et al., 1975; Mislevy et al., 1996; Mislevy et al., 2005). Studies conducted by Haines et al. (1965) indicated an inverse relationship between animal gain and heavy rainfall in south Florida. In addition, animals were found to have lost weight when the average maximum temperatures were above 32 C or below 21 C and highest gains were evident when the average maximum temperatures were between 24 and 29 C. Crude protein was similar for all grass entries during the cool season of 2001-2002 and did not differ much between the November and March sampling periods averaging 217 and 218 g kg-1, respectively (Table 5). Small differences in IVOMD were found between grass entries harvested in

November and March averaging 658 and 692 g kg-1, respectively. Both CP and IVOMD obtained during the cool season were excellent.

Significant differences in CP and IVOMD were found among grass entries during the 2002 warm season. Crude protein concentration of Stargrass 2000 was higher (P<0.05) than Florona stargrass for both the 9 May and 2 July sampling dates (Table 6). Concentration of CP during the warm season ranged from 94 to 130 g kg-1 and was adequate for beef cattle production. Tifton 85 and Stargrass 2000 both had the highest IVOMD content during the warm season. Average IVOMD content over all grasses ranged from 529 to 551 g kg-1. These values are common for cynodon grasses during the warm season. Harvesting these grasses during the cool season of 2002-2003 showed a dramatic increase in both CP and IVOMD when compared with the warm season (Table 6). Average CP concentration increased from 22 October thru 18 December followed by a slight decrease on 17 Jan. 2003. Generally, during October most tropical grasses show a slight decrease in forage production, and continue this decrease through January followed by a major increase during March or April (Table 1-3). As forage growth rate decreases during the cool season, CP and IVOMD increase, resulting in high quality forage (Table 6). In vitro organic matter digestion was greatest in Tifton 85 and Stargrass 2000 forage for the 22 October, 21 November, and 17 January harvests, but Florona stargrass was the highest on 18 December (786 g kg-1). Digestibility followed an inverse relationship to DB yield, increasing from October through December. Average IVOMD for 17 Jan. 2003 was only 572 g kg-1 or a 25% decrease from December. This was the result of a frost, which occurred at the experimental site when the official temperature


Table 6. Crude protein (CP) concentration and in vitro organic matter digestion (IVOMD) of Cynodon grasses harvested during the warm (April 15 – Oct. 15) and cool (Oct. 16 – April 14) season of 2002 - 2003.

CP IVOMD Grass 9 May 2 July 27 Aug 9 May 2 July 27 Aug ----------------------------------------------------------------------------- g kg-1 ---------------------------------------------------------------------------- Bermudagrass Warm Season2000 106 bH 133 ab 96 a 542 b 546 b 510 c Jiggs 112 b 129 ab 92 a 509 c 520 c 523 bc Tifton 85 106 b 130 ab 97 a 556 b 586 a 568 a Stargrass Florona 95 c 120 b 86 a 540 b 530 bc 504 c 2000 132 a 140 a 99 a 588 a 573 a 542 b Avg 110 128 94 547 551 529

Grass 22 Oct 21 Nov 18 Dec 17 Jan 22 Oct 21 Nov 18 Dec 17 Jan ----------------------------------------------------------------------------- g kg-1 ---------------------------------------------------------------------------- Bermudagrass Cool Season2000 116 c 157 bc 254 a 201 bc 583 bc 660 c 756 bc 585 ab Jiggs 106 d 160 bc 259 a 199 bc 571 c 630 d 746 c 569 b Tifton 85 131 b 160 b 231 c 191 c 643 a 692 a 759 bc 569 b Stargrass Florona 113 cd 148 c 259 a 210 ab 596 b 661 bc 786 a 533 c 2000 146 a 185 a 243 b 222 a 647 a 686 ab 763 b 606 a Avg 122 163 249 205 608 666 762 572 H Means within the column followed by the same letter(s) during the warm and cool seasons are not different at the 0.05 level of probability (Waller Duncan k-ratio, k=100).

dropped to 1 C (Kalmbacher 2004). Studies indicate when Cynodon grasses are frozen, CP and IVOMD decline about 10 and 50 g kg-1, respectively, during the first week (Mislevy, 2002) following a freeze.

SUMMARY

Average annual DB yield for Cynodon grasses harvested monthly in central Florida was 26.4 Mg ha-1 over 3 yr. Grasses averaged 29.5 Mg ha-1 over the first 2 yr, followed by a 30% decrease in year three. Average DB yield during the warm season was 16 Mg ha-1 and 9.9 Mg ha-1 during the cool season. The percentage of total seasonal yield produced during the cool season was 38%. These data are 10 percentage units higher than four Cynodons grown in Immokalee (Mislevy and Everett, 1981). During the warm season Bermudagrass 2000, Jiggs, and Tifton 85 were the greatest yielding, while in the cool season Bermudagrass 2000, Jiggs, and Florona stargrass were the greatest. Overall the greatest yielding entries were the 3 bermudagrasses averaging 26.3 to 27.6 Mg ha-1 over 3 yr. The CP concentration and IVOMD was generally lowest during August and September and highest during November and December prior to a freeze. Following a freeze CP and IVOMD in Cynodon grasses has been found to decline by 19% (124 down to 102 g kg-1) and 31% (584 down to 400 g kg-1), respectively, four weeks after a freeze (Mislevy 2002). Crude protein concentration was variable among Cynodon entries during both the warm and cool season. However IVOMD concentration was generally highest for Tifton 85 and Stargrass 2000.

REFERENCES

Gallaher, R.N., O.C. Weldon, and J.G. Futral. 1975. An aluminum block digester for plant and soil analysis. Soil Sci. Soc. Am. Proc. 39:803-806.

Haines, C.E., H.L. Chapman, Jr., R.J. Allen, Jr., and R.W. Kidder. 1965. Roselawn St. Augustine- grass as a perennial pasture forage for organic soils of south Florida. Bull. 689. Florida Agric. Exp. Stn., Univ. of Florida, Gainesville.

Hambleton, L.G. 1977. Semi automated method for simultaneous determination of phosphorus, calcium, and crude protein in animal feeds. J. Assoc. Off. Anal. Chem. 60:845-854.

Kalmbacher, R.S. 2004. Climatological Report 2003. Res. Rep. RC-2004-1, Range Cattle Res. and Educ. Center, Univ. of Florida, Gainesville.

Mislevy, P. 2002. How good is your pasture grass after a freeze? The Florida Cattlemen and Livestock Journal 67 (3); 62-63.

Mislevy, P., W.F. Brown, L.S. Dunavin, W.D Hall, R.S. Kalmbacher, A.J. Overman, O.C. Ruelke, R.M. Sonoda, R.L. Stanley, Jr. and M.J. Williams. 1989. Florona Stargrass. Circ. S-362. Florida Agric. Exp. Stn., Univ. of Florida, Gainesville.

Mislevy, P., W.F. Brown, R.S. Kalmbacher, L.S. Dunavin, W.S. Judd, T.A. Kucharek, O.C. Ruelke, J.W. Noling, R.M. Sonoda, and R.L. Stanley, Jr. 1995. Florakirk


Bermudagrass. Cir. S-395. Florida Agric. Exp. Stn., Univ. of Florida, Gainesville.

Mislevy, P., G.W. Burton, A.R. Blount, and F.G. Martin. 2005. Dry biomass yield and nutritive value of bahiagrass cultivars in central Florida. Soil Crop Sci. Soc. Florida Proc. 64:75-79.

Mislevy, P. and P.H. Everett. 1981. Subtropical grass species response to different irrigation and harvest regimes. Agron. J. 73:601-604.

Mislevy, P. and F.G. Martin. 1998. Comparison of Tifton 85 and other Cynodon grasses for production and nutritive value under grazing. Soil Crop Sci. Soc. Florida Proc. 57:77-82.

Mislevy, P., F.G. Martin, G.W. Burton, and L.F. Santos. 1996. Influence of grazing frequency on production and quality of Paspalum, Brachiaria, and Setaria grasses. Soil Crop Sci. Soc. Florida Proc. 55:97-103.

Mislevy, P., F.G. Martin, B.J. Downs, and K.L. Singer. 1990. Influence of grazing management on forage quality of stargrass. Soil Crop Sci. Soc. Florida Proc. 49:162-166.

Moore, J.E. and G.O. Mott. 1974. Recovery of residual organic matter from in vitro digestion of forages. J.Dairy Sci. 57:1258-1259.

Prates, E.R., H.L. Chapman, Jr., E.M. Hodges, and J.E. Moore. 1975. Animal performance by steers grazing Pensacola bahiagrass pasture in relation to forage production, forage composition, and estimated intake. Soil Crop Sci. Soc. Florida Proc. 34:152-156.

SAS Institute. 1989. SAS/STAT User=s Guide, Version 6, 4th ed. SAS Institute, Cary, NC.

Sinclair, T.R., P. Mislevy, and J.D. Ray. 2001. Short photoperiod inhibits winter growth of subtropical grasses. Planta 213:488-491.

Tilley, J.A. and R.A. Terry. 1963. A two-stage technique of the in vitro digestion of forage crops. J. Br. Grassl. Soc. 18:104-111.


St. Augustinegrass Phosphorus Requirement Using Hydroponic Culture

Min Liu, J.B. Sartain,* L.E. Trenholm, G.L. Miller, and P. Nkedi-Kizza

ABSTRACT

St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze] is widely used in Florida as a lawn grass. At present P fertilization of Florida lawn grasses is based on soil tests which were designed for agronomic crops in a production culture. Little information exists relative to the exact P requirement of St. Augustinegrass. The objectives of this study were to determine the critical tissue P concentration of St. Augustinegrass and the critical solution P concentration for optimum growth and quality using solution culture techniques. Established pots of ‘Floratam’ were subjected to P treatments in solution culture within the range of 0 to 775 mg m-3 P for 148 days. Measurements included tissue and root growth rates, tissue and root P concentration and visual ratings of turfgrass quality. Phosphorus treatments increased tissue and root P concentration with each successively higher P application. The best turf quality was achieved with the highest P treatment (775 mg m-3). Turfgrass receiving 31 mg m-3 P attained the highest root growth among the treatments. Tissue growth rate increased with P treatments in a quadratic manner to a maximum value of 1.0 g m-2 day-1. According to linear plateau regression analysis, the critical solution P concentration was 111 mg m-3 and the critical tissue P level was 1.6 g kg-1 on dry weight basis for optimum growth. The critical tissue P level can be used in future research to determine the minimum fertilization level of St. Augustinegrass to achieve the critical tissue P level.

INTRODUCTION

St. Augustinegrass is a widely used lawn grass along the Gulf Coast in the U.S. Haydu et al. (2005) reported that St. Augustinegrass represented 64% of the total sod production in 2003 in Florida, of which 69% was ‘Floratam’. Uses included home lawns, public landscape and roadsides; accounting for 0.7 million hectares and contributing $2 billion to the Florida economy (Hodges et al., 1994). St. Augustinegrass is a moderate fertility warm-season turfgrass that requires 150 to 300 kg N ha-1 yr-1 (Cisar et al., 1991). Phosphorus is the nutrient generally needed in the third greatest quantity by turfgrass. The only scientific study (Wood and Duble, 1976) that documented P requirement in St. Augustinegrass indicated that its growth in soils extremely low in P was impacted during the first eight weeks of establishment with P application.

Recently attention has been directed towards P fertilization of Florida lawn grasses, because P is

recognized as an element of impairment of water bodies and streams. Eutrophication of surface waters, the proliferation of aquatic plants, is caused by a surplus of available nutrients such as P and N. Eutrophication can cause a decrease in dissolved oxygen in waterways, a situation in which the whole eco-system declines. For this reason, P applied to home lawn grasses has to be monitored to precisely meet the grass P requirement without excessive application that ends up as runoff or leachate.

Solution culture has been a basic tool in plant physiological studies, such as root growth (Blum et al, 1977; Erusha, 1986; Kim et al., 1999) and plant mineral nutrition studies (Breeze et al., 1984; Clement et al., 1974). Solution culture studies are popular because they provide a controlled environment where one or more variables can be readily changed to test plant responses. Solution cultures have been extremely valuable for testing plants without an essential element in solution to induce nutrient-deficiency symptoms and determine which nutrients are essential and the optimum concentrations required by plants. The most widely used nutrient solution in plant studies is Hoagland solution (Hoagland and Arnon, 1950). In nature, soil solution P concentration may vary from 3.1 to 310 mg m-3 (Asher and Loneragan, 1967). Asher and Loneragan (1967) produced solution P concentrations of 1.2, 6.5, 31, 149, and 756 mg m-3 to mimic and bracket soil solution conditions. Breeze et al. (1984) used P concentrations (mg m-3): 3.1, 12.4, 49.6, 198.4, and 992 in a perennial ryegrass (Lolium perenne L.) P uptake study.

The critical tissue P concentration is normally regarded as the minimum concentration associated with near maximum yield. The nutrient concentration in the plant at 90% of maximum growth has often been termed the critical concentration (Ulrich and Hills, 1967). Critical concentration could be statistically determined from the shape of the yield response curve in relation to concentration of P in the selected tissue. Knowledge of the minimum P concentrations for plant growth has been used as a means to diagnose the P status of many plants (Hartt, 1955; Ulrich, 1952). The critical P concentrations for agronomic crops such as rice, cotton, and corn have been studied extensively, and for some forage grasses the critical P levels have also been established. Wedin (1974) reported that P levels in cool-season grasses range from about 1.4 to 5.0 g kg-1 and in most situations below 2.0 g kg-1 is considered deficient. Oertli (1963) reported that healthy bluegrass (Poa spp) and bermudagrass [Cynodon dactylon (L.) Pers] contain 1.2 to 2.4 g kg-1 P, respectively. Phosphorus deficiency levels were found to be 0.5 to 0.8 g

Min Liu and J.B. Sartain,* Soil and Water Science Dept., Univ. of Florida, 414 Newell Hall, PO Box 110510, Gainesville, FL 32611-0510; L.E. Trenholm, Environment Horticultural Dept., Univ. of Florida, Gainesville, FL 32611-0670; G.L. Miller, Crop Science Dept., North Carolina State Univ., Raleigh, NC 27695; P. Nkedi-Kizza, Soil and Water Science Dept., Univ. of Florida, McCarty Hall, PO Box110290, Gainesville, FL 32611-0290.




kg-1, respectively, for bluegrass and bermudagrass. Martin and Matocha (1973) reported that the critical P concentration of 4-wk-old ‘Pangola’ digitgrass (Digitaria eriantha) was from 1.2 to 1.6 g kg-1. The critical P level of buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] (46 days) was 3.0 g kg-1 (Christie, 1975). Literature relative to the critical tissue P concentration of St. Augustinegrass was not found. At present P fertilization of Florida lawn grasses is based on soil tests which were designed for agronomic crops in a production culture. Little information exists relative to the exact P requirement of St. Augustinegrass. The objectives of this study were to determine the critical tissue P concentration of St. Augustinegrass and the critical solution P concentration for optimum growth and quality using solution culture techniques.


A glasshouse study was conducted at the Turfgrass Envirotron at the Univ. of Florida, Gainesville. Floratam St. Augustinegrass was chosen as the test cultivar is it the most widely used St. Augustinegrass cultivar. Six levels of P (0, 1.24, 6.2, 31, 155 and 775 mg m-3) with five replicates were employed. Certified sod, collected from the G.C. Horn Turfgrass Field Laboratory at the Univ. of Florida, was washed to remove soil from the root system. Sod was cut to a size of 15- × 30-cm rectangle and transferred to the hydroponics system on 27 June 2004.

Nalgene tubs (31 cm × 16 cm × 12 cm) were used as the hydroponic containers. The outside surfaces of the containers were painted with black latex paint first and white afterwards to prevent light penetration. A 10-mm inner diameter polynvinyl chloride (PVC) pipe was used to make a rectangle frame (15 cm × 30 cm). A piece of poly-hardware cloth was attached to the frame and fitted on the corners of opening of the container to form a grass bedding surface. Since the frame was not fixed to the container, the frame/screen with grass could be removed to change solution or check solution pH periodically. The grass pieces were placed on the bedding surfaces. Nutrient solution level in the container was adjusted to touch the screen to induce root growth. Roots penetrated the screen and grew into the solution after about three weeks. Then the solution volume was reduced to approximately 1.5 cm below the frame to create an air zone between grass stolons and solution surface to avoid water damage and algae growth on the grass. An air compressor was used to supply air to the nutrient solution.

Nutrient solution was slightly modified from what was reported by Breeze et al. (1984) by replacing Sequestrene Fe 138 with Sequestrene Fe 330, eliminating CaSO4 and doubling the concentrations of all nutrient elements. The nutrient solution was changed every other day to regulate pH, maintain nutrient concentrations and minimize salt accumulation. The P treatments were applied on 17 Oct.

2004 at which time the turfgrass was exhibiting P deficiency. The study was terminated on 14 March, 2005. The treatments were arranged in a randomized complete block design. Glasshouse temperature was maintained at an average 22 °C with a range of 18°C to 30 °C. The relative humility was maintained at approximately 75%.

Top growth was clipped to 7.5 cm approximately monthly, once the dry matter production reached harvestable quantities (approximately 15 cm height), for a total of seven collections. Clippings were dried at 70 °C for 48 h, and weighed. Root materials were clipped to 4 cm on 8 Sept., 2004 and 27 Nov., 2004 when they were approximately 12 cm long. Root materials were washed with distilled water to remove the potentially adsorbed salts, dried at 70 °C for 72 h and weighed. The dry tissue and root samples were ground to 2-mm and ashed. Samples were analyzed for P by spectrophotometry using the molybdenum-reduced molybdophosphoric method (Hanlon et al., 1994). Turf visual quality was rated biweekly using a scale of 1 to 9 where 1 represents brown, dormant turf and 9 represents superior quality (Skogley and Sawyer, 1992).

Statistical analysis (analysis of variance) was performed by SAS (SAS Inst., 1987). Mean separation was done using Duncan’s Multiple Range test at a 0.05 significant level (PROC GLM). The relationship between average turfgrass tissue growth rate and solution P and tissue P were determined using linear plateau analysis (PROC NLIN).


Turf Quality

Mean St. Augustinegrass visual quality increased with each incremental increase in solution P concentration in the range from 0 to 775 mg m-3 (Fig.1). St. Augustinegrass treated with two highest P concentrations, 155 and 775 mg m-3, recovered from the P deficiency conditions and their mean turf quality values were 6.8 and 7.2, respectively (Fig.1). The control turf treated with zero P in solution suffered severely from P deficiency with a mean turf quality value of 2.5 (Fig.1). Turf treated with zero P declined in quality over time and by the end of the study was dead. Solution P levels of 1.24, 6.2, and 31 mg m-3 were generally not adequate to supply sufficient P for turf to recover from deficiency and promote optimum growth. Mean turf quality values from these treatments were below 5.5, which is widely used as a minimum value for acceptable turf quality.

Tissue P and Root P

The initial tissue P concentration of the St. Augustinegrass tested was as high as 4.8 g kg-1 on a dry weight basis. After three harvests prior to treatment application, P deficiency (<1.0 g kg-1 on dry weight basis)


Figure 1. Mean turf quality (based on biweekly ratings where 1 represents brown, dormant turf and 9 represents superior quality) response to solution P concentration. Means marked by the same letter do not differ (DMRT, P = 0.05).

was induced based on deficiency symptoms. Tissue P concentration changes prior to and after P application treatments for the six P treatments as shown in Fig.2. Tissue P concentration of turfgrass receiving zero P continued to decline over time until it reached a value of 0.48 g kg-1 after the fourth harvest. By the end of the study most of the turfgrass in the zero P treatment was dead, but those portions which were still alive contained 0.45 g P kg-

1. This could be considered the minimum P concentration to keep St. Augustinegrass alive.

0

1

2

3

4

5

6

7/19 8/18 9/17 10/17 11/16 12/16 1/15 2/14 3/16

Tiss

ue P

, g k

g-1 0

1.24

6.2

31

155

775

Date, Month/day (2004-2005) Figure 2. Tissue P concentration over time as influenced by solution P concentration.

The relationship between tissue P levels and solution P concentration is presented in Fig.3. The highest tissue P level was achieved with application of 775 mg m-3 solution followed by P treatment of 155 mg m-3. There were no differences in P concentration among the four lowest P treatments. One possible reason for this observation is that the turfgrasses with the four lowest P levels remained P deficient (<1.0 g kg-1 on dry weight basis) during the experimental period.

Figure 3. Relationship of solution P and tissue P concentration on termination date. Means marked by the same letter do not differ (DMRT, P = 0.05).

The relationship between root P levels and solution P concentrations is shown in Fig. 4. Root P levels increased with increasing solution P concentration. Similar to the tissue P levels, the highest P treatment resulted in the highest root P concentration (Fig. 4), but unlike tissue P, root P concentration differences were found for even the four lowest solution P levels. Additionally, the root P concentration resulting from the four lowest P levels was identical or even slightly higher than levels found in leaf tissue when P supplies were deficient. This indicates that the primary use of P is for root growth rather than top growth when P is deficient. However, when P supplies were sufficient, root P concentration (Fig. 4) with the two highest P levels was lower than those in foliage tissue (Fig. 3). It is possible that, when P is deficient, a higher quantity of P is required in order to produce more roots to overcome the P deficiency.

Figure 4. Relationship of solution P and root P concentration on termination date. Means marked by the same letter do not differ (DMRT, P = 0.05).

Tissue Growth Rate and Root Growth Rate

Phosphorus fertilization influence on tissue growth rate is rarely observed in St. Augustinegrass in the field because of the generally medium to high available P status in Florida soils and perceived relatively low P requirement by St. Augustinegrass (Wood and Duble, 1976). Tissue growth rate (Fig. 5) was affected by solution P

9

3.5 A

B A

7

0 6

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cl Oil 2 g. C ~ D " 1 -'.::: ~ _) B

~ 4 E ~ 1

C C C C F 0 .5

0 0 124 61 31 155 775

Solution P, mg m-3

0 1.24 6_2 31 155 775 Solution P, mg m-3

1.4 A

L2 ·oo B ~

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0 L24 6_2 31 155 775

Solution P, mg m-3


concentration. Tissue growth rate increased with solution P levels in a quadratic manner to a maximum value. According to linear plateau regression analysis (Fig. 5), solution P concentrations beyond 111 mg m-3 did not result in increased tissue growth rate (R2 = 0.86, p<0.0001, CV = 15.5). Christians et al. (1979) investigated the N, P and K effects on quality and growth of Kentucky bluegrass (Poa pratensis) and creeping bentgrass (Agrostis palustris) using solution culture. No response to P levels in solution was observed, which indicated that the requirements of these two species for P, under the conditions established, were met at or below the lowest P level of 2 mg L-1 in solution. Asher and Loneragan (1967) found that P at 155 mg m-3 produced maximum dry weights of clover (Trifolium subterraneum L.) and erodium [Erodium botrys (Cav.) Bertol.] and yields of bromegrass (Bromus rigidus Roth) and cape weed [Cryptostemma calendula (L.) Druce] were close to maximum in a similar hydroponics study.

Solution P (mg m-3)0 100 200 300 400 500 600 700 800

Tiss

ue g

row

th ra

te (g

m-2

day

-1)

0.0

.2

.4

.6

.8

1.0

1.2

Figure 5. St. Augustinegrass tissue growth rate relative to solution P concentration.

Root growth rates (Fig.6) were affected by solution P concentration although the effect was less as compared with tissue growth rates. Turfgrass receiving 31 mg m-3 attained the highest root growth rate among the P levels applied. Asher and Loneragan (1967) reported that P at 31 mg m-3 produced maximum top and root growth for sliver grass [Vulpia myuros (L.) Gmel.= Festuca myuros L.]. Root P concentration in the presence of P at 31 mg m-3 was 0.7 g kg-1, which indicates that roots require a smaller quantity of P for optimum growth than tissue (Fig.7). Only three mean categories were separated for root growth rates (Fig. 6) indicating that the extent of the effect of solution P concentration on root growth was less than that on tissue growth. Additionally, turf receiving no P produced substantial root growth (Fig.6). The large reserve of P in the parent plant (approximately 5 g kg-1 P in tissue (Fig.1) and correspondingly high P level in stolons (not measured)) can be a P source for root growth in case there was no P application or P supplies were not sufficient.

Figure 6. Root growth rate relative to solution P concentration. Means marked by the same letter do not differ (DMRT, P = 0.05).

Critical Tissue P level

A yield response curve in relation to concentration of P in the selected tissue is commonly used to determine the critical P concentration. Tissue growth rate was increased with tissue P concentration in a quadratic manner to a maximum value (Fig. 7). According to linear plateau regression analysis, the critical tissue P level was 1.6 g kg-1 on dry weight basis for the optimum growth (R2 = 0.88, p<0.0001, CV = 15.4). Wedin (1974) reported that P concentration in cool-season grasses range from about 1.4 to 5.0 g kg-1. Jones (1980) suggested that in most situations concentrations below about 2.0 g kg-1 indicate a deficiency for plant growth while 3.0 to 3.5 g kg-1 is usually necessary for optimum yields. For warm-season grasses, the P concentration in plant tissue should be logically lower for the optimum yield compared with cool-season grasses because the higher growth rate dilutes the P concentration in plant tissue. Burton et al. (1997) reported that phosphorus concentration of the 1993 Pensacola bahiagrass forage receiving 56 kg P2O5 ha-1, above which no significant yield increase occurred, averaged 1.5 g kg-1.

y = 0.99 - 0.00004(x – 110.9)2

R2 = 0.86, p< 0.0001, CV = 15.5 plateau = 1 critical x =111

Figure 7. St. Augustinegrass tissue growth rate relative to tissue P concentration.

•

•

I

• •

•

3.5

:i' !: -5 -:>-, 2.5

" :j: -0

tJi <:-E

B B - -0 00 0 ~

1.5

1.24

1.2

1.0 •• , . 8 •

.6

.4

• . 2

A -AB AB

- -

6.2 31 155

Solution P, mg m·3

• • •

y = 1.05 -0.51(x - 1.56)' R2 = 0.88, p<0.0001, CV = 15.4 plateau = 1 critical x = 1.6

AB -

T/5

•

•

0.0 ~ --~ --~ --~ --~ ---~ --~ --~-J 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5

Tissue P (g kg·1)


CONCLUSIONS

Although the best turf quality was achieved by the highest P treatment, tissue and root growth rates were maximized at lower P concentrations. Turfgrass receiving P at 31 mg m-3 attained the highest root growth among the treatments., however, the critical solution P concentration for optimum tissue growth was 111 mg m-3. This study indicated that St. Augustinegrass can be expected to respond favorably to P applications if the tissue P concentrations are less than 1.6 g kg-1. Otherwise, no additional shoot growth would be expected if all other growth factors were adequate. In practice, conventional P fertilization programs normally use soil test P status as an index which categories soil P into very low, low, medium, high, very high levels. However, the soil P value range for each category was initially designed for agronomic crops and possibly does not fit St. Augustinegrass actual need. Future studies may include determining a suitable soil testing procedure for St.Augustinegrass P recommendations and establishing the critical soil P level by relating it to the critical plant tissue P level.

REFERENCES

Asher C.J., and J.F. Loneragan. 1967. Response of plants to phosphate concentration in solution culture: I. growth and phosphorus content. Soil Sci. 103:225-233.

Blum, A., G.F. Arkin, and W.R. Jordan. 1977. Sorghum root morphogenesis and growth I. Effect of maturity genes. Crop Sci. 17:149-153.

Breeze, V.G., A. Wild, M.J. Hopper and L.H. Jones. 1984. The uptake of phosphate by plants from flowing nutrient solution. J. Exp. Botany. 35:1210-1221.

Burton G.W., R.N. Gates, and G.J. Gascho. 1997. Response of Pensacola bahiagrass to rates of nitrogen, phosphorus and potassium fertilizers. Soil Crop Sci. Soc. Florida Proc. 56:31–35.

Christie, E.K. 1975. Physiological responses of semi-arid grasses. II. The pattern of root growth in relation to external phosphorus concentration. Aust. J. Agric. Res. 26:437-446.

Cisar, J.L., G.H. Snyder, and P. Nkedi-Kizza. 1991. Maintaining quality turfgrass with minimal nitrogen leaching. Univ. Florida, IFAS. Coop. Ext. Ser. Bull. 273..

Clement, C.R., M.J., Hoper, R.J., Canaway and L.H.P. Jones. 1974. A system for measuring the uptake of ions by plants from flowing solutions of controlled composition. J. Exp. Botany. 25:81-98.

Erusha, K.S. 1986. Turfgrass rooting responses in hydroponics. M.S. thesis. Univ. of Nebraska, Lincoln, NE.

Jones, J.R., Jr. 1980. Turf analysis. Golf Course Manage. 48(1):29–32.

Hanlon, E.A., J. G. Gonsalez, J. M. Bartos. 1994. Colormetric soil P determination. p. 17-18. In IFAS extension soil testing laboratory chemical procedures and training manual. Univ. Florida, IFAS, Coop. Ext. Ser. Cir. 812.

Hartt, C.E. 1955.The phosphorus nutrition of sugar cane. Hawaiian Planters’s Record. LV(1): 33-46.

Haydu, J.J., L.N. Satterthwaite and J.L. Cisar. 2005. An economic and agronomic profile of Florida’s sod industry in 2003. Food Res. Econ. Dep, Univ. Florida, EIR 02-6.

Hoagland, D.R., and D.I Arnon. 1950. p.2-32. In The water-culture method for growing plants without soil. Californai Agric. Exp. Stn., Ext. Circ. 346.

Hodges, A.W., J.J. Haydu. P.J. van Blockland, and A.P. Bell. 1994. Contribution of the turfgrass industry to Florida’s economy 1991/92: A value added approach. ER 94-1. Univ. Florida, Gainesville, FL.

Kim, K.N., R.C. Shearman, and T.P. Riordan. 1999. Top growth and rooting responses of tall fescue cultivars grown in hydroponics. Crop Sci. 39:1431-1434.

Martin, W.E., and J.E. Matocha. 1973. Plant analysis as an aid in the fertilization of forage crops. p. 393-425. In L. M. Walsh and J.D. Beaton (ed.) Soil testing and plant analysis. Rev. Ed. Soil Sci. Soc. Am., Madison, WI.

Oertli, J.J. 1963. Nutrient disorders in turfgrass. California Turfgrass Culture, Vol. 12 (3): 17-19.

SAS Institute. 1987. SAS user’s guide: Statistics. 6th ed. SAS, Cary, NC.

Skogley, C.R., and C.D. Sawyer. 1992. Field research. p. 589-614. In D.V. Waddington, R.N. Carrow, and R.C. Shearman (ed.) Turfgrass. Agron. Monogr. 32. ASA, CSSA, and SSSA, Madison, WI.

Ulrich, A. 1952. Physiological basis for assessing the nutritional requirements of plants. Ann. Rev. Plant Physiol. 3:207-228.

Ulrich, A., and F.J. Hills. 1967. Principles and practices of plant analysis. p. 11-24. In Soil testing and plant analysis. Part II. SSSA Spec. Publ. Ser. No. 2, Soil Sci. Soc. Am., Madison, WI.

Wedin, W.F. 1974. Fertilization of cool season grasses. p. 95–144. In D.A. Mays (ed.) Forage fertilization. ASA, CSSA, and SSSA, Madison, WI.


Wood, J.R., and R.L., Duble. 1976. Effect of nitrogen and phosphorus on establishment and maintenance of St. Augustinegrass., Texas A& M Univ., TAES, Progress Report. Vol. PR-3368C, PR 1976-3368.


ENVIRONMENTAL QUALITY Commercial Microbial Inoculums and Their Effect on Plant Growth and

Development: A Synopsis of Current Literature and Case Studies

P. G. Kalogridis*, J. M. S. Scholberg, R. J. McGovern, R. B. Brown, and K. L. Buhr.

ABSTRACT

Microbial competitive exclusion is an ecological approach that reduces resource access by pathogens, thereby hampering their development. Effective use of microbial inoculums can thus prevent pathogens from reaching economic thresholds and also enhance nutrient availability via increased microbial assimilation and nutrient cycling. Several research groups have demonstrated the effectiveness of this approach, and used inoculated compost to enhance crop resistance to soil plant pathogens. Development of commercial microbial inoculums aimed to enhance repressive soil properties can therefore improve crop performance and yields. Commercial microbial inoculums (MI) are generally marketed as individual microbe species or as a diverse mixture of microbes typically found in healthy soils. Use of microbial products with one or only a few species may hamper successful establishment of microbial populations in adverse soil environments. Creating favorable soil environment, on the other hand, appears to be critical, to boast overall effectiveness of MI in controlling soil pathogens. Application of microbial inoculums can be considered with any production system that includes organic amendments that provide an energy source for soil microbes. Examples include landscape bedding plant production, golf courses that regularly top-dress fairways with compost, ornamental container nursery stock as well as agronomic and vegetable crops that utilize organic amendments to provide a suitable substrate for beneficial soil microbes. Perhaps the greatest potential use and impacts of commercial microbial inoculums will be in enhancing productivity in developing countries since these regions have limited access to alternative approaches for pathogen control and improving inherent soil fertility.

INTRODUCTION

Development of more sustainable agricultural systems may require improved use and integration of soil microbes for enhancing plant growth and soil health. The premise that the elimination of soil fauna was desirable to enhance plant growth has prevailed for many years. Although historically soil microbes were not considered to be beneficial for the growth of most plants, current research has demonstrated the beneficial effects of these organisms in plant disease suppression. The development and maintenance of diverse soil microbial populations thus can

form a viable strategy for enhancing plant performance and thereby reducing the dependence of farmers on agrochemicals and potential environmental impacts.

This paper provides an overview of the role of microbial processes in relation to plant growth, including a synopsis of some of the past and current research efforts, along with an outline of a number of case studies of commercial application of microbial inoculums. In addition, a cost comparison of conventional products will also be provided. Finally, the potential benefits of improved use of microbial inoculums in environmentally sensitive areas and development of more sustainable agricultural production will be explored.

SOIL MICROBIOLOGY, THE PLANT RHIZOSPERE, AND BIOCONTROL OF

PHYTOPATHOGENS

Soil Microbiology and Soil Quality

The complexity of soil biology has long been established but the potential contribution of the biosphere on enhancing crop production and sustainability of agroecosystems is still not fully appreciated. The community of organisms in the soil is collectively known as the soil food web (Tugel and Lewandowski, 2000). The soil food web consists primarily of plants, arthropods, earthworms, nematodes, protozoa and microbes. Soil microbial populations are considered to be comprised of both bacteria and fungi. These microbes contribute to plant growth primarily by decomposing organic compounds and releasing nutrients and simple carbon compounds to plants as well as other organisms in the soil food web.

Soil microorganisms thus play an essential role in soil ecosystems due to the fact that they are involved directly in nutrient cycling of C, N, P, and S (Kertesz and Mirleau, 2004) decomposition of residues and wastes (Deni and Penninckx, 1999), plant and human soil-borne diseases (Jensen and Nybroe, 1999), mycorrhizae association (Jordan et al. 2000). Soil systems that have an inherent capacity to suppress pathogen growth are referred to as “suppressive soils” (Kremer and Li, 2003; Peters et al. 2003).

P. G. Kalogridis, Dayspring, Agronomic Services Inc., Winter Garden, FL347448; J. M. S. Scholberg and K. L. Buhr, Agronomy Dep., Univ. of Florida, Gainesville, FL 32611-0500; R.J. McGovern, Plant Pathology Dep., Univ. of Florida, Gainesville, FL 32611-0680; and R.B. Brown, Soil and Water Science Dep., Univ. of Florida, Gainesville, FL 32611-0510. This research was supported by the Florida Agric. Exp. Stn. and is approved for publication as Journal Series No. N-00000.

* Corresponding author ( [email protected] ) Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:21-30 (2006)

Soil microbes further degrade pollutants within the soil and play an important role in purifying water as it moves



through soil strata (Tugel and Lewandowski, 2000). Assimilation of nutrients within microbial biomass enhances the retention and recycling of these nutrients. After decomposition of these organisms they subsequently become a food/energy source for other organisms within the soil food web.

Soil microbial populations are immense. It is estimated that the population of microbes within one gram of dry soil or the equivalent of one teaspoon of soil can range between 100 million to 1 billion individuals (Tugel and Lewandowski, 2000). These microbial populations can vary greatly in numbers and diversity. Within the soil, microbial activity is greatest within close proximity of plant roots. This biologically active zone surrounding plant roots (the rhizosphere) consists of increased populations of microbes that proliferate in the carbon-enriched root exudation zone. The number of microbes on the root surface is 10 to 100 times greater than it is at a distance of 0.6 cm.

Within this area an accelerated amount of digestion of minerals and nutrients by soil microbes takes place which greatly enhances their availability to the growing plants (Jones et al., 1994). The apparent intense competition for water and nutrients in this region actually turns out to be a symbiotic relationship between soil microbes and plant roots. Plant roots release simple carbon compounds that stimulate microbial growth, which in turn enhances nutrient availability by plant roots. These nutrients are also utilized by the soil microbes resulting in increased microbial populations adjacent to plant roots.

The presence of large microbial populations in close contact with plant stimulates nutrient cycling and provides readily available source of plant nutrients to the plant. These mutually beneficial associations, many of which are not clearly understood, promote many specific symbiotic associations between plants and microbes. Microbes can temporarily immobilize nutrients during periods when plants are not actively growing thereby prevent nutrients leaching. The process of assimilation of inorganic nutrients into microbial components results in a chelation of inorganic compounds into a carbon-based substance which provides the soil food web with a more stable yet inexpensive slow-release nutrient source. This characteristic of microbial growth has provided a natural model for the commercial fertilizer chelation process.

Soil microbes also enhance soil structure through their life processes. Exudates and excretions as well as the death of the organisms bind soil particles together forming stable soil aggregates. These aggregates enhance water percolation, air/gas exchange, water holding capacity, and soil tilth which in turn increase nutrient retention, aggregate stability, while reducing soil erosion.

A large body of knowledge exists that provide support for the perception that root exudates may act as messengers that promote biological and physical

interactions between roots and soil organisms (Walker et al., 2004). Some compounds identified in root exudates that have been shown to play an important role in root-microbe interactions in legumes include flavonoids. These compounds activate Rhizobium meliloti genes responsible for the nodulation process (Peters et al., 1986) and although some studies may not be conclusive, flavenoids may also be responsible for vesicular-arbuscular mycorrhiza colonization (Becard et al., 1992; Trieu et al., 1997). On the other hand, physically unprotected root cells are under constant attack by pathogenic microorganisms. For their survival, roots require continuous secretion of phytoalexins, defense proteins, and other as yet unknown chemicals (Flores et al., 1999).

Microorganisms and Plant Health

Although our understanding of the role of soil microorganisms within the rhizosphere is limited, its significance is appreciable. In recent years there is increased interest in the potential for disease suppression in soil and improved use of beneficial soil microbes for the control of pathogenic organisms. Promoting microbial activity and diversity may thus prevent soil pathogens from establishing themselves on plant surfaces, obtaining food or generating metabolites that are toxic and/or directly inhibit pathogens (Tugel and Lewandowski, 2000). This phenomenon is generally accomplished by direct predation by soil microbes or through a process called competitive exclusion. Competitive exclusion prevents the soil pathogen from reaching economic threshold values and thereby allowing sustainable production without the intervention of chemical pesticides.

It has been observed that presence of soil organic matter enhance crop disease resistance. It also known that the presence of organic matter in the soil is one of the most limiting requirements for successful and diverse microbial population growth. Scientists have directed research over the years to determine the effect of soil microbes on disease resistance properties exhibited in plants. Researchers at Ohio State University explored the relationship between soil organic matter, soil microbes and disease resistance in plants (Hoitink et al., 2002). Recently it has also been shown that some microorganisms colonizing roots in compost mixes actually activate biochemical pathways in plants, leading to resistance to root as well as foliar diseases (Hoitink et al., 2002). This mechanism explains the often-observed phenomena that plants grown on “healthy organic soils” are more disease tolerant. It has also been observed that amending soil with compost can improve plant disease resistance to soil pathogens (Hoitink et al., 2002).

Other research showed that amending soil with composts resulted in increased cotton yield compared to non-amended control treatments (Koenning et al., 2003). Similar results were reported for potato due to reduced incidence of potato early dying disease (Verticillium


dahliae) (LaMondia et al., 1999). Additional studies showed positive linear relationships with chicken litter applications rates and bacterial and/or fungal colony-forming units (CFU) in cotton producing soils (Riegel and Noe, 2000).

Studies evaluating the effects of soil amendments on root rot and sugarcane growth at Louisiana State University showed that increases in soil organic matter resulted in disease suppression and improved crop growth. In this case increases in microbial activity levels associated with soil organic matter addition provided a suitable indicator of the potential for disease suppression (Dissanayake and Hoy, 1999).

Research at the Lake Alfred Citrus Research and Education Center of the University of Florida-IFAS showed that citrus soil amended with composted municipal waste (CMW) reduced the incidence of P. nicotianae of 5-week-old susceptible citrus seedlings from 95% to as low as 5% (Widmer et al, 1999).

Mechanism for Disease Suppression by Beneficial Microorganisms

Based on the above information, it can be concluded that presence and/or prevalence of beneficial soil microorganisms can control diseases and they thus may serve as biocontrol agents. Disease control provided by these micro organisms is attributed to one or more of four different mechanisms. The first mechanism is increased competition by non-pathogenic microorganisms for exudates (sugars, etc.) leaking out of seeds during germination or out of expanding root tips. Pathogens moving towards these nutrient sources must compete with beneficial organisms present near infection ports, which reduce infection success rate and therefore disease occurrence. Secondly, some biocontrol agents produce antibiotics that are effective against pathogens. Thirdly, micro-arthropods such as springtails (Collembola) and mites (Acari) actually search out pathogen propagules in soils and either parasitize or consume them. The fourth mechanism involves the induction of systemic resistance in plants by microorganisms present in composts (Hoitink et al., 2002).

Effects of Organic Amendments on Disease Incidence

Field studies in Ohio were conducted to evaluate the effects of compost amendments and disease severity development in organic and conventional processing tomato (Lycopersicon esculentum L.) production systems. When disease pressure was high, the incidence of anthracnose fruit rot was reduced in organic tomato plots amended with a high rate of composted cannery wastes compared to that in non-amended control plots. In conventional tomato production, however, composted yard waste increased disease severity on foliage both years but reduced incidence of bacterial fruit spot when disease pressure was high. Furthermore the incidence of

anthracnose was not affected by composted yard wastes (Abbasi et al., 2002).

The above results indicate the importance of biological suppression of plant diseases utilizing composts. However, these studies also showed that not all organic amendments displayed consistent disease resistant responses. Similar conflicting results were reported in a comparison of biological control agents with no significant differences in plant mortality observed between treated and control plots (Reid et al., 2002). It may thus be concluded that the quality and microbial biodiversity may differ between organic soil amendment materials. Although organic amendments may have similar ingredients and/or composition, differences in the biodiversity of the inoculation media used and/or the processing methodology used may greatly affect their overall pathogenic action. However that does not imply that compost is not a suitable medium for the introduction of known beneficial microbes.

Biocontrol with Trichoderma hamatum 382

In Ohio, compost-amended soil media was inoculated with Trichoderma hamatum 382 (T382), a biocontrol agent that induces systemic resistance to disease in plants (Table 1). This approach has been shown to reduce the severity of several different types of foliar diseases (Hoitink et al., 2002). The results of this experiment revealed that the compost that did not receive any T382 inoculum did not provide adequate control of foliar and stem disease while the inoculated compost provided effective control of Botryospheria dieback. Table 1. Effect of Trichoderma hamatum 382 (T382) in composted bio-solids amended container medium on the severity of dieback, plant senescence, and plant health†.

Potting Mix

Mean Dieback Severity ‡

Mean % Plants Senescence §

Mean % Symptomless

Plants Control 2.4 20.8 25.0 T382 1.5 6.3 66.7 LSD 0.05 0.4 14.1 20.4 † Hoitink et al., 2002. ‡ Liners potted, in a container medium consisting of “aged “ pine bark, sphagnum peat, composted bio-solids, expanded shale and sand (9:1.5:0.75:1:0.33;vol./vol.) (control) or inoculated with T382 granular inoculum. § Mean dieback severity based on four blocks of 12 plants per treatment (n=48) using a scale in which 1 = symptomless, 2 = slight stunting, 3 = severe stunting, and 4 = dead plant.

These results are consistent with controlled greenhouse studies that showed that composts generally do not provide systemic effects against plant diseases unless they are inoculated with biocontrol agents that can activate systemic resistance (Hoitink et al., 2002).

Research conducted by the USDA-ARS Biocontrol of Plant Diseases Laboratory in Beltsville, Maryland confirms this phenomenon. In this case, seeds treated with specific beneficial soil microorganisms had increased seed stand, plant height and fresh weight with lower severity of


root rot compared to those treated with chemical fungicides or other antagonists (Mao et al., 1997).

Similar seed treatments utilizing biological disease suppression agents in silviculture by inoculating Douglas Fir (Pseudotsuga menzieii) seeds also resulted in reduced proliferation of soil pathogens without a significant loss in seed germination (Hoefnagels and Linderman. 1999). Even in highly saturated soil environment, such as rice production systems, antagonistic bacterization of naturally infected seeds occurred which reduced Fusarium moniliforme incidence in seedbox and seedbed tests. In three years of field trials five strains of antagonistic bacteria consistently reduced F. moniliforme (Rosales and Mew, 1996). Thus, it appears that composts that contain inherent biocontrol agents can enhance disease resistance. However from an agricultural production standpoint, consistency of application requires that composts should be inoculated to insure these disease resistance qualities.

Commercial Microbial Inoculum—Plant Growth Activator Plus

The above results provide scientific support for the potential benefits of appropriate use of microbial inoculum on a commercial scale. Microbial inoculum products that offer a broader range of species may be more effective since it is more likely that at least one or more organisms will survive and/or thrive under specific and/or adverse soil environments. Commercial inoculum that consists of a single or a combination of a few microbial species thus may not provide consistent results and thus may not meet expectations of producers. In order to ensure more consistent performance, one microbial product included as many as 52 different strains of naturally occurring soil organism. This product contained bacteria from various species of Bacillus, Streptomycetes and beneficial Pseudomonas, phosphorus-solubilizing bacteria, nitrogen-fixing bacteria along with essential amino acids, vitamins B, B2, B3, B12, C, K, biotin, folic acid and natural sugars. Trichoderma fungi was also included in this proprietary mixture (Organica Biotech, Inc., 1999).

Researchers at the Rutgers University showed that Organica Plant Growth Activator Plus (PGA Plus), a microbial inoculum (MI) provided definitive suppression of an active fungal pathogen (Magnaporthe pose) on a variety of turf (Baron Kentucky Bluegrass) susceptible to that pathogen (Table 2). Up until 2 weeks after the final application (8/12/99) of Organic PGA Plus MI provided substantial suppression of the fungal pathogen (Organica Inc., 1999).

Regional differences in climate, soils, and plant species may pose limitations on the effectiveness of commercial MI and testing of commercial products within specific crop production areas is highly recommended. Florida’s climate and sandy soils can impact the effectiveness of MI, especially during the hot and humid summer months when rainfall frequency and intensity is high, successful

establishment may be difficult. The inherent lack of organic matter in Florida soils and the rapid decomposition rates of applied organic matter may further limit the effectiveness of MI greatly. However for the production of many ornamental crops, incorporation of

Table 2. Comparison of the effect of application of Microbial Inoculua (Organica PGA Plus) on the control of summer patch (Magnaporthe pose) pathogen in Kentucky Bluegrass (Poa pratenis) compared to conventional chemical fungicides (Heritage 50W, azoxystrobin, Chipco Triton 1.67SC, azoxystrobin; Clearys 3336 50W, thiophanate-methyl)†.

Date Microbial inocula or chemical fungicide Percent control

August 2,1999 Heritage 50W (2oz. per 1000 sq. ft. 93%

Chipco Triton 1.67SC (1oz. per 1000 sq.ft) 87%

Clearys 3336 50W (8oz. per 1000 sq.ft.) 90% Organica PGA Plus (2oz. per 1000 sq.ft.) 88%







† Unpublished studies by P. Majumbar, B.B. Clark, G.W. Towers, and E.N. Weibel, Dept. of Plant Pathology Rutgers University, New Brunswick, NJ.

organic matter is a standard production practice and is widely practiced. The rapid decomposition of organic matter also facilitates the increase in microbial activity which may favor beneficial microbes and enhance competitive exclusion and microbial predation.

One of the limitations to successful adaptation of MI by commercial growers is the lack of information on the performance of specific organisms under local conditions. To address this issue, researchers at the University of Florida conducted three plant trials in Southwest Florida (McGovern et al., 2000). The first trial consisted of comparing the effectiveness of PGA Plus MI applied at one-eight of the recommended rate was compared to chemical fungicides and results are outlined in Table 3. It was shown that, even at this low application rate, use of MI gave satisfactory results.

Table 3. Comparison of the effect of application of Microbial Inocula(MI) on the control of Fusarium Wilt (Fusarium oxysporum) pathogen in Lisianthus (Eustoma grandiflorum) compared to chemical fungicides†.

Product Final mortality AUMPC‡ Plant

height (cm) Control 69.4% 1220 10.5 AtEze 61.1% 1171 10.2 PGA

Plus 41.6% 400 12.4

Heritage 25.0% 295 11.6 † McGovern et al., 2002b. ‡ AUMPC is an indicator of how rapidly plants die, high AUMPC #

indicates rapid death rate.


Soil Microbial Diversity and Pathogen-Suppressive Soils

During a second test trial the same protocol was employed except the recommended label rate of 0.06 g m-2

was applied consistently over the trial period. The second trial compared the effectiveness of a PGA Plus MI (applied at recommended application rate) to other commercial microbial inoculate (MI) and results are outlined in Table 4. Although this study was not geared to directly compare products, results showed that PGA Plus MI, which contains a diversity of microbial species, was superior to products with limited or a single microbial species.

Soil microbial diversity seems to be related to the concept of “suppressive soil”. This concept has evolved from the phytopathology field from the term “soil-borne pathogens suppressive soils”. Formerly three types of pathogen-suppressive soils were considered functional. The first type is that the phytopathogen does not establish or is unable to persist. In the second type, the pathogen is present but fails to cause damage on susceptible crops. In the last case the pathogen causes some disease damage, but the disease becomes progressively less severe even though the pathogen persists in soil (Sylvia et al., 1999; Walsh et al., 2001). Although the effectiveness of the PGA Plus MI has been determined under laboratory conditions the effectiveness of microbial species biodiversity in pathogen-suppressive soil media under commercial field production conditions needs to be quantified.

Table 4. Comparison of the effect of application of Microbial Inocula (MI) on the control of Fusarium Wilt (Fusarium oxysporum) pathogen in Lisianthus (Eustoma grandiflorum) compared to other Microbial Inocula (SoilGuard and RootShield) and control†.

Product Final mortality AUDPC‡ AUMPC§

Control 94.4% 1749 10.5 SoilGard 83.3% 1784 10.2 Rootshield 66.6% 1746 12.4 PGA Plus 52.8% 1658 11.6 † Unpublished study by McGovern, Gulf Coast REC, Bradenton, FL. ‡ AUDPC is an indicator of how rapidly the disease progresses (the lower the better) § AUMPC is an indicator of how rapidly the plants die (the lower the better).

The third trial consisted of comparing the effectiveness of PGA Plus MI on the control of Fusarium Wilt (Fusarium oxysporum) pathogen in two varieties of Basil seeds. Seeds were planted in a peat medium and MI was applied as a soil drench. Seedlings were later transplanted into the field and MI was reapplied at 2 week intervals throughout the crop cycle. Plants were monitored weekly for symptoms of Fusarium wilt and results are outlined in Table 5. Basil treated with MI showed a drastic decrease in the incidence of Fusarium wilt with both susceptible and resistant varieties benefiting from applications. These three research test trials showed that microbial inoculums which contained multiple species were capable of colonizing organic matter and plant tissue and providing effective control of plant soil pathogens under laboratory conditions.

Table 5. Comparison of the effect of application of Microbial Inocula (MI) on the control of Fusarium Wilt (Fusarium oxysporum) pathogen in two varieties of Basil seeds (Genovese and Nufar)†.

Cultivar of Basil and

Treatment Used

Fusarium Incidence

Root Discoloration

Bacterial Blight

Yield (oz. / plot)

Genovese Control 29.2% 1.5 5.8 125.8

Genovese & PGA P. 2.1% 1.0 4.8 178.0

Nufar Control 2.1% 3.3 5.2 180.2 Nufar & PGA PLUS 0.0% 1.8 5.0 206.2 † McGovern et al., 2002a.

A method of microbial diversity analysis has been developed and has been applied to golf courses (Sachs and Luff, 2000). Protocol for monitoring and determining microbial biodiversity provides a reporting mechanism similar to that of standard soil nutrient analysis. Microbial diversity analysis or species richness is a measurement of microbial diversity or an indicator of the number of different species or types of microorganisms that are present in a sample. In soil or compost, high species richness diversity (SRD) promotes numerous interspecies relationships and interactions between populations. Species richness and diversity is important because it allows for a more varied and flexible response to environmental fluctuations and adverse conditions which increases the resilience of the soil system. The SRD determination of microorganisms in a particular microbial functional group is an index of the variety of microbes in that functional group. This index is derived from a formula that weights the variety of species within a functional group from a normalized analysis of species richness against the total number of microorganisms associated with that functional group. This index can be compared to other samples from a similar matrix (soil, compost, or liquid) and can be used to determine the impact of various crop management and agricultural practices on microbial diversity. Table 6 shows an example of an agricultural soil analysis utilizing the six individual SRDs to determine Total Species Richness Diversity (SRDT). The concept of the SRDT index, along with individual SRDs, is also applied to a bedding plant study and results are outlined in Table 7.

Commercial application of MIs may be triggered by a failure of conventional methods to control plant pathogens in a cost-effective manner. As a case study, at a Central Florida Theme Park (CFTP) repeated crop failures utilizing chemical fungicides in a particular bedding plant location (Kalogridis, unpublished). This flower bed consistently lost 27% of the 1500 bedding plants installed


Table 6. Agricultural soil analysis utilizing the six individual measures of species richness diversity (SRD) to determine Total Species Richness Diversity (SRDT) †.

Parameter Enumeration, Colony Forming Units (CFU) per gram dry weight (gdw)

Species richness density (SRD) index

Heterotrophic plate count (aerobic) 1.8 x 10 8 CFU/gdw 2.9 Anaerobic bacteria (includes facultative anaerobes) 1.6 x 10 7 CFU/gdw 1.9 Yeasts and Molds 1.1 x 10 6 CFU/gdw 2.3 Actinomycetes 3.3 x 10 4 CFU/gdw 1.2 Pseudomonas 2.4 x 10 7 CFU/gdw 1.2 Nitrogen-fixing bacteria 3.0 x 10 4 CFU/gdw 0.7

Total Species Richness Diversity (SRDT) --------------------------- 10.2 (Moderate Diversity)

† Unpublished study by V.H. Bess, BBC Laboratory, Tempe, AZ.

Table 7. Total Species Richness Diversity (SRD)†. SRD Index Classification for agricultural soils Greater than 12.5 High Diversity 7-12.5 Moderate Diversity Less than 7 Low Diversity † BBC Laboratory, Tempe, Arizona (Bess, unpublished).

on a monthly basis. Removal of chemical fungicide applications and the introduction of MI were initiated on a weekly basis until favorable results could be determined. By the third MI application noticeable decline in plant replacements was observed. By the fifth MI application weekly plant replacements were no longer necessary. Upon reviewing these results a second problem flower bed was selected and treated with MI with the same results. At this point it was decided to extend the use of MI applications to all the bedding plants within the entire theme park.

Now that the fungal diseases were abated the next challenge became how to sustain a diverse microbial population and provide effective pest control, while delivering an enhanced appearance on a long-term basis. Performance of landscape ornamentals is generally based on their aesthetic function and thus optimal appearance is critical. However, considering the appreciable installation and maintenance cost then the length of useful service in a landscape venue also becomes an important factor. Performance is quantified as crop rotations which are typically replaced with new seasonal crops every three months. In order to preserve the microbial enhancement and longevity of the plant material, soil recommendations needed to provide for long term growth and stability of microbial diversity over a succession of flower crops. This requires a more holistic approach and soil management practices need to be geared towards establishing a functional ecosystems. This approach will allow enhance ecological functions and crop nutrient availability via improved microbial assimilation and nutrient cycling.

Approaches for Enhancing Microbial Diversity and Pathogenic Suppression

Beneficial microbial species competing with pathogens for food sources provides an ecological basis for pathogen suppression. General management practices were developed for enhancing pathogenic suppression in

flower borders in a Central Florida theme park (Appendix 1). Following the recommendations outlined in Appendix 1, resulted in a significant reduction and/or elimination chemical fungicides use in flower beds. It also improved the overall soil fertility and eliminated the need to replace the soil every two years, which used to be standard practice. Pertinent aspects of the management of this system over a 2-year period will be outlined in the section below.

Addition of corn gluten meal (8% N) as an organic nitrogen source and mineral green sand (7% K2O) to the soil was aimed to promote development of beneficial soil organisms and to improve the nutrient content of the compost added to the soil. A small amount of supplemental liquid bio-organic nitrogen was used since this N source is least harmful for microbial populations. The addition of these organic nutrient sources to the compost promotes more sustained growth of beneficial soil microbes. In addition to organic soil amendments, recommendations also include addition of micronutrient and foliar applications of phosphite ion, a special form of phosphorus which also has fungistatic properties and promotes flowering. Foliar MI spray formulations included molasses as a sticker. The molasses also acted as a food source for the microbes which quickly colonized the leaf surface of the flower crops thereby preventing the growth of foliar pathogens.

A microbial diversity analysis was also conducted on the original flower beds to determine the total species richness diversity (SRDT) of the amended soil. Four samples where analyzed which had an averaged SRDT value of 8.8. More detailed sample analysis for one of these samples is shown in Table 8. Based on these results, it was concluded that addition of organic soil amendments and periodic inoculations of the soil along with appropriate management practices allowed for sustained microbial population growth and increased biodiversity.

A commercial soil pathogen laboratory, on the other hand, provided the following assessment of the soil from the original flower bed: “A medium amount of Fusarium was isolated from the soil, 260 colony forming units per gram, along with a medium amount of Pythium, 204 colony forming units per gram. The sample tested negative


Table 8. Total Species Richness Diversity (SRD) for sample bedding plants †.

Parameter Enumeration Species Richness Diversity (SRD)

Heterotrophic Plate Count (Aerobic) 6.2 x 107 CFU/gdw 3.5

Anaerobic Bacteria 8.3 x 107 CFU/gdw 1.1 Yeasts and Molds 2.8 x 105 CFU/gdw 2.4 Actinomycetes 3.0 x 106 CFU/gdw 1.4 Pseudomonas 3.8 x 105 CFU/gdw 0.9 Nitrogen-fixing bacteria 3.0 x 106 CFU/gdw 0.5 % Moisture 36% -------- Total Species Richness Diversity (SRDT) ------------------------ 9.8

( Moderate diversity) † Test results from sample submitted to BBC Laboratories, Tempe, Arizona.

for Rhizoctonia and Phytopthora. The lab manager of this facility was unaware of series of the MI treatments and concluded that there was enough soil pathogens present to warrant an application of chemical fungicide.

However, based on a visual assessment of the original flower bed treated with MI, it was concluded that the economic threshold had not been reached and that the plant material was responding positively to the benefits of microbial competitive exclusion.

Benefits and Cost Comparisons of Phytopathogen Biocontrol

A major benefit to the use of MI for commercial operations is the reduced use of toxic agrochemicals which benefits both crop protection personal and people that come in direct contact with the plant material. A microbiological inoculum consists of naturally occurring biological organisms, it does not carry a pesticide label, and there are no restrictions on the timing or frequency of its application. Moreover, its activity is derived from living organisms which will be self sustaining in the soil, provided adequate amounts of organic nutrients are being added.

A cost analysis of chemical fungicide products used during the utilization of the MI product as of June 14, 2001 is outlined in Table 9. Based on these figures, it is concluded that the cost of MI is relatively low compared to most other commonly used products for soil pathogen control. MI, when combined with posphite, a commercially available nutrient/fungicide, was still well within the range of competitive pricing for soil and foliar pest control products. The cost of application on the original two test bedding plant plot shows an 82% decline in product utilization and an 87 % savings in cost of application (Tables 10 and 11). These figures show that 3.5 kg of chemical fungicide per month was utilized with limited control for a period of five months as compared to 0.3 kg per month of MI which was utilized successfully for a period of eleven months.

Over 4000 applications of MI were made on over two million ornamental bedding plants over a two-year period with consistently successful results for a total product cost

of only $8,100. As a result, both chemical use and maintenance cost can be reduced and the relatively low application cost of MI products therefore may afford potential users with a management strategy that is environmentally sound and economically viable.

Table 9. Cost analysis of Microbial inoculum compared to chemical fungicide in inventory†.

Product $/lbs.-Gal. $/Oz. Oz./Application $/Application

Mancozeb dg $3.54 $0.22 24 $5.28

Banrot $6.60 $0.41 6 $2.46 3336 WP $18.50 $1.16 8 $9.28 Aliette WDG $17.00 $1.06 32 $33.92

Chipco 26019 $25.10 $1.57 32 $50.24

Heritage $345.00 $21.56 1 $21.56 Subdue Maxx $600.00 $4.69 1 $4.69

PGA PLUS $15.52 $0.97 2 $1.94

Phosphoric acid (P03

$52.00 $0.41 2 $0.82

PGAPlus & P03

67.52 $1.38 2 $2.76 † Kalogridis, P. 2001 (unpublished case study for a Central Florida theme park).

Table 10. Fungicide usage and cost for five months for 2600 plant bedding crop†

Fungicide Amount Used Cost 3336WP 280 oz $313.60 Subdue 17.5 oz $82.80 Chipco 128 oz $197.12 Alliette 176 oz $186.56 BanRot 16 oz $23.20 Total 618 oz $803.28 † Cromwe1l, H. 2001 (Unpublished feasibility study for a Central Florida theme park)

Table 11. Microbial inoculum usage and cost for eleven months for 2600 plant bedding crop †.

Location Amount of PGA Cost CFTPa 40 oz $37.20 CFTPb 74 oz $68.82 Total 114 oz $106.02 † Based on production budget Cromwell, H. 2001. (Unpublished feasibility study for a Central Florida theme park)

Additional, cost savings and other benefits can be realized through the use of MIs. These include immediate cost savings due to the reduction in the number of plant replacements necessary to maintain the flower beds and the corresponding labor to install them. Also the labor for pest control applications can be reduced to monthly spray applications with continued use along with the cost of chemicals. However the greatest cost benefit can be realized in the reduction of flower crop rotations necessary throughout the year. Assuming that flower crops can be maintained for longer periods of time, then the number of flower crop rotations can be reduced during the growing season.


For the specific case study outlined above, one flower crop rotation amounts to approximately 150,000 plants per rotation with 5-6 rotations per year. Six crop rotations per year equate to approximately 900,000 plants and with the cost of plants and labor averaging $1.10 per plant, the costs of annual flower crop installation is on the order of $990,000. The effective utilization of commercial microbial inoculums in flower crop soils can extend the yield length of service and totally omit one or more flower crop rotations resulting in a potential cost savings to the enterprise of $165,000.00 or a budget savings of approximately 16% of annual total installation costs.

Another benefit of soil microbial enhancement is the elimination of soil replacement (change-outs) in the individual flower beds. This practice calls for the removal of the top 12-14” of soil in the flower beds every two years in an effort to physically remove soil pathogens and replace the soil with new soil media. This particular venues total combined bedding plant cultivation area is approximately 10 acres. This practice involved the net soil replacement of 5 acres per year and is very labor intensive.

Results of this commercial application of microbial inoculums in the case study outlined above resulted in the successful growth of over two million bedding plants under field conditions utilizing microbially inoculated soil over the course of two complete growing seasons. Soil pathogen, as well as foliar fungal pest control, were achieved without the use of chemical fungicides at reduced costs with greater safety to the applicators. The appearance (“show quality”) of the landscape flower crops were enhanced in an environmentally responsible manner by eliminating the use of fungicides which are a state recognized element of impairment for water quality. These results are consistent with The Green Industry Best Management Practices (BMPs) and the environmental stewardship directives of the executive management of the enterprise.

SUMMARY AND CONCLUSION

Based on current scientific research on microbial inoculums and successful commercial implementation of this technology, it is concluded that the use of commercial microbial inoculums enhances plant growth, reduce both production cost and environmental impacts. However, this paper does not attempt to persuade producers to adopt these practices but aims to demonstrate that based on results from scientific studies and demonstration trials commercial microbial inoculums can be cost-effective. However, their successful adaptation, to a large extent depends on the management skills of the end-user. His/her ability to successfully utilize MI to suppress pathogens will require a working knowledge of the biological concepts associated with utilizing microbial inoculums. If systems are not properly managed, MI will not work and crop failures may occur.

However, the large scale commercial application in the case study outlined in this article describes the successful integration of slow-release chemical fertilizer along with bio-solids compost derived from municipal sewage sludge. Alternatively, switching to cow manure compost and substituting blood meal for the chemical fertilizer component this production system not only maintains its effectiveness but will also meet the production criteria for certified organic cropping systems.

Organic matter containing diverse microorganisms can be utilized to produce compost/manure tea which can be used as a foliar spray for the control of pathogens on leaf surfaces and readily transported to enhance crop production in other farming regions. Current estimates suggest that pesticide use could be reduced by 50% or more, without any reduction in pest control and/or change in cosmetic standards of crops, through implementation of sound ecological pest controls such as crop rotations and biocontrols (Pimentel, 1997).

The key issue remains to maximize production for the producer based on their individual management abilities while protecting the natural resources surrounding the farming operation. In order to accomplish these goals, all aspects of crop production from all production system components must be given the same objective analysis and not discarded out of fear, ignorance or individual personal agendas.

On a different geographical scale, the greater contribution of commercial microbial inoculums may be their potential utilization to enhance the sustainability of production agriculture in developing countries. Third world countries are facing the greatest agricultural challenges while having limited access to external inputs and other critical production resources and these countries may greatly benefit from utilization of this technology.

ACKOWLEDGEMENTS

The authors want to thank Drs. Williamson, Allen, and Ezenwa for their review of this paper and their suggestions for improving this manuscript.

APPENDIX

Bedding plant recommendations for Central Florida theme park operation (2001). In an effort to maintain show quality of bedding plant material and simultaneously build soil fertility, establish sustained nutrient levels and microbial soil biodiversity the following amendments are recommended:

1) Every fall, winter and spring crop rotations apply one inch of ¼” compost to the bedding plant soil and incorporate with a rototiller. Avoid compost applications during the summer crop rotations to


allow for residual compost to be utilized over the summer months.

2) Prior to incorporation of the compost apply the following nutrients.

• 15 lbs. per 1000 sq.ft. of 14-12-14 three month slow release fertilizer.

• 10lbs. per 1000 sq.ft. Lawn Booster 8% Corn Gluten slow release nitrogen fertilizer.

• 10 lbs. per 1000 sq. ft. Green Sand 7% slow release potassium and trace elements.

3) Incorporate nutrient amendments and compost into bedding plant soil.

4) Drench soil around installed plants with compost tea when available.

5) Apply MI microbial inoculate weekly along with PO3 and micronutrient foliar application for four weeks then apply bi-weekly for one month then monthly

6) Apply bio-organic Turfmaster 12-5-3 liquid fertilizer as an interim fertilizer as required.

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Guidelines for Compost Sanitation

R. N. Inserra*, M. Ozores-Hampton, T. S. Schubert, J. D. Stanley, M. W. Brodie, and J. H. O’Bannon

ABSTRACT

Compost obtained from variable sources of raw materials such as municipal solid waste, yard trimmings, biosolids, and other organic materials is a widely used soil amendment for agricultural, landscape, mulch and soil mitigation purposes. When this aerobically biodegraded product is appropriately composted and mixed at temperatures of 55 C for 15 days (windrow composting methods) or five days (in-vessel composting methods), it is theoretically free of pathogens including nematode plant pests and weeds. However, improper composting procedures and poor sanitation practices result in incomplete elimination of nematode plant pests and pathogens from the composting material or contamination of the finished product with raw material from the environment. Compost containing live nematode plant pests or weeds can hamper crop production. Additionally, it can spread regulated nematodes in nematode-certified citrus and ornamental nurseries resulting in loss of nematode certification or rejection of plant shipments from regulatory officials. Major factors that prevent the complete elimination of nematode plant pests in compost operations include: i) improper composting procedures such as oversized organic piles or windrows that cannot be turned properly and lack of uniform temperature distribution in the composting material and ii) poor sanitation practices which cause contamination of the compost with nematode plant pests. Proper sanitation requires careful planning to eliminate the risks from the environment due to insufficient engineering of the compost facility, unsanitized machinery or inadvertent mixing of raw material and finished product. Establishment of a well-designed composting facility that implements appropriate composting and sanitation procedures is costly and labor intensive. Typically, such facilities will require subsidization, because the up-front costs of a properly designed and operated facility cannot be recouped by the sale of finished stable product.

INTRODUCTION

Composting is a biological decomposition process in which microorganisms convert raw organic materials into relatively stable humus-like material. During decomposition, microorganisms assimilate complex organic substances and release inorganic nutrients (Metting, 1993). Therefore, compost may be defined as a mixture of decomposed raw material consisting of organic matter from:

• municipal solid waste (MSW), which includes paper, cardboard, food waste, yard waste, rubber, leather, textiles, wood, and small amounts of contaminants consisting of glass, metals, and plastics;

• yard trimmings (YT), which include leaves from trees and shrubs, pine needles, grass clippings, tree bark, woody branches, shredded prunings, mineral soil, and plant roots;

• biosolids (BS), which include the solid portion of waste from municipal sewage treatment plants;

• food wastes from restaurants, grocery stores, and institutions; and

• wood wastes from construction and/or demolition.

Agriculture industries produce other organic matter that can be composted. These agricultural organic materials include:

• poultry, dairy, horse, feedlot, and swine manures;

• wastes from food processing plants;

• spoiled feeds; and

• harvest wastes.

Compost that is in a stable state of decomposition can be used 1) as a soil amendment for both food and ornamental crop production, 2) to replace soil removed with nursery trees and sod, 3) as a mulch to decrease evapotranspiration and control weeds, or 4) as all or part of potting media for containerized plant production (Hoitink et al., 1991; Ozores-Hampton et al., 1998; Ozores-Hampton and Peach, 2002).

Composting provides a sustainable method of managing some forms of waste material, and properly produced compost is a valuable resource. However, improper preparation, storage or transport of compost can result in the spread of plant pests including plant-parasitic nematodes. Growers risk introducing serious pathogens into their fields by using improperly manufactured compost, and citrus and ornamental nurseries can lose their nematode-certification if regulated nematode pests are introduced with low quality compost. The purpose of this paper is to describe principles and provide guidelines for producing pathogen-free mulches that will conform to a standard necessary for nematode-certification.

R. N. Inserra, T. S. Schubert, J. D. Stanley and J. H. O’Bannon, Div. of Plant Industry, FDACS, Gainesville, FL 32614-7100. M. Ozores-Hampton, Univ. of Florida, IFAS, South West Florida Res. Educ. Center, Immokalee, FL 34142-9515; and M. W. Brodie, Div. of Plant Industry, FDACS, Naples, FL 34109-6384. Contribution No. 485, Bureau of Entomology, Nematology and Plant Pathology – Nematology Section.

WASTE MANAGEMENT AND COMPOSTING

Composting the organic fraction of the waste stream has become an important commercial enterprise and a necessity for municipalities as an economical means of alleviating a steadily increasing "garbage crisis" (Rathje, *Corresponding author ( [email protected] ). Contribution

published in Soil Crop Sci. Florida Proc. 65: 31-37 (2006).



1991). At the end of the past century, more than 70 % of our trash was buried in 5,500 active landfills across the country (Rathje, 1991). Environmentally safe and available sites for additional landfills are becoming increasingly scarce. Landfills are extremely expensive to build and manage. Paper and organic waste (discarded yard wastes, wood, and food residues) represent 63% of the total solid waste volume disposed of in a landfill (Rathje, 1991). A large portion of this organic waste can be reused for agricultural purposes if the organic waste is properly treated and transformed into compost. In recent years, composting practices and technologies have progressed remarkably and have been promoted and sometimes mandated by both government and private agencies involved in waste management. Manuals, journals, journal articles and websites are available that offer updated information about new composting methodologies, advanced procedures and technical advice (NRAES, 1992).

The principle of composting by exploiting biodegradation processes by aerobic microorganisms is well known. In commercial operations, the raw organic material is mechanically shredded or ground after removal of thick plastic and metallic components that may be present in the organic material. The ground mass is then placed in piles or windrows to decompose by aerobic biodegradation. The material may be sprayed with water, a water suspension of biodegrading bacteria, or with enzymes to enhance the aerobic biodegradation process. During the biodegradation process, which lasts several weeks to several months, the piles are treated by applying water when needed and turned several times in order to favor aerobic bacterial and fungal activity. Additionally, the turning exposes all parts of the organic pile to high decomposition temperatures, which are necessary for the thermophilic organisms to degrade the raw organic matter. When the biodegraded product is in a state of stable decomposition, it is screened mechanically to break up or remove large pieces of organic material and then stored in cleaned areas free from contamination by harmful animal and plant pathogens and pests until used.

PLANT-PARASITIC NEMATODES IN COMPOSTING MATERIAL

Unwanted organisms, which include animal, human, and plant pathogens, harmful insects; and weed seeds, may be present in the raw material. Plant-parasitic nematodes are pests that also occur in raw material (especially in yard trimmings) used for compost production. Yard wastes are a major source of plant-parasitic nematode introduction into composting operations, because these organisms occur in soil and inhabit roots and leaves of plants. Many plant-parasitic nematodes cause serious economic damage to agronomic crops, fruit trees and ornamentals, and if present in compost can be spread in agricultural operations.

The state of Florida regulates the movement of several nematode pests of citrus (Citrus sp.) in order to protect the citrus industry from the damage that these pests can cause. Regulated citrus nematode pests include species that do not occur in Florida as well as species which do occur in Florida. Species that are not presently found in Florida can be introduced by various means, the main one being the entry of unauthorized plant material. Debris from this introduced material can end up in yard wastes and composting operations. Species that are established in Florida include the burrowing nematode (Radopholus similis), the citrus nematode (Tylenchulus semipenetrans) and the coffee lesion nematode (Pratylenchus coffeae). The burrowing and coffee lesion nematodes have wide host ranges which include many horticultural and agronomic crops as well as several weed hosts. The burrowing nematode is a major pest in ornamental production infecting acorus (Acorus sp.), aroids [anthuriums (Anthurium sp.), pothos (Pothos sp.), etc.], bamboos (Bambusa sp.), gingers (Zingiber sp.), ornamental bananas (Musa sp.) and palms (Chamaedorea sp., Cocos sp., etc.). The coffee lesion nematode infects aglaonema (Aglaonema sp.), coffee (Coffea sp.), rubber plants, weeping figs (Ficus sp.) and other ornamentals. The citrus nematode is widespread in Florida, but infects mainly citrus. In Florida, both citrus and ornamentals are commonly grown in plant nurseries and in yards around dwellings. These plants can be a component of yard trimming wastes that are used in composting operations.

The burrowing nematode and other nematode species occurring in Florida are regulated by many other states and countries including Arizona, California, the European Union, and Japan. These nematodes can occur associated with susceptible plants, weeds and soil throughout the Florida environment and can be easily introduced into composting and soil operations. Regulated nematodes must be excluded from Florida nurseries exporting plants to domestic and international markets. Thus, the Florida ornamental and citrus industries require high quality, nematode-free organic products, which include compost that is added in soil mixes for potting material or used directly as soil amendment. Section 5B-44.003 of the Florida Administrative Code requires that media including peat, sand and other soil types, lime rock and shells for use in citrus nurseries and orchards should be certified free of the citrus nematode pests mentioned above. Therefore, compost used in citrus nurseries and orchards must be certified free of citrus nematode pests. Ornamental nurseries that produce plants for export to national and international markets that enact nematode regulations must also be certified free of nematodes before exporting their plants. It is imperative for these Florida nurseries to use nematode-free components (including compost) for their growing media or risk the loss of nematode certification. Complete nematode elimination is required to certify the final compost for regulatory purposes.


COMPOSTING REGULATIONS

The process of aerobic biodegradation produces heat in the decomposing organic matter. Temperatures up to 74 °C (165 °F) have been recorded within compost piles in Florida composting operations. These temperatures are sufficient to kill pathogenic organisms; however, lower temperatures that are insufficient to kill these organisms occur near the pile surface and in the low portion of the piles, requiring the composting material to be turned at intervals. According to the United States Environmental Protection Agency (USEPA) 40 CFR 503 rule, windrow composting should be conducted at a temperature of at least 55 °C (131°F) for 15 days or 5 days with in-vessel composting methods. For the windrow composting method the organic mass should be turned 5 times to expose every part of the pile to the high temperature in order to eliminate pathogens and kill weed seeds (USEPA, 1994). This rule should be followed for the elimination of nematode plant pests from the composting of organic materials. Phytoparasitic nematodes are killed at warm temperatures of 43.3-46 °C (110-115 °F); however, the exposure time for nematode mortality varies with nematode species and parasitic habits. Endoparasitic species which develop and reproduce inside root tissues require longer exposure time than ectoparasitic species that develop and reproduce in the soil and on the root surface. Thus, the finished compost obtained by following USEPA Regulation 503 is, theoretically, free of these pests. However, in some commercial composting operations the mature compost may be contaminated by raw material accidentally mixed with the finished product during transfer to the dump site or by other sources such as water runoff and both vehicular and foot traffic. Therefore, additional guidelines are needed to prevent contamination by nematodes after the composting process has occurred.

FACTORS AFFECTING NEMATODE ELIMINATION AND CONTAMINATION IN

COMPOSTING OPERATIONS

The major factors that prevent the complete elimination of nematode plant pests in compost operations are improper composting procedures and poor sanitation practices. Improper composting procedures are frequently caused by oversized organic piles or windrows that cannot be turned properly resulting in a lack of uniform temperature distribution in the pile. Cool pockets in improperly composted piles favor the survival of many pathogenic organisms and especially temperature-tolerant fungi, such as Fusarium oxysporum f. sp. lycopersici and nematode plant pests (Noble and Roberts, 2004). Improper composting conditions will result in the failure to eliminate nematode populations within the organic material. Residual populations of live nematodes have been detected on the surface of piles that have not been properly composted according to USEPA Regulation 503. In some cases, the residual nematode population may be

undetectable by routine nematological analyses and its detection requires long term bioassay tests in a greenhouse.

Many nursery sanitation principles are applicable to compost operations (Esser, 1979, 1980, 1984, 1996; Lehman, 1980). Since plant-parasitic nematodes commonly occur in the Florida environment, they can be easily reintroduced in the finished product by conditions as those shown in Figure 1. Environmental factors include inappropriate sites for the composting operation, such as a site with a history of regulated nematodes (e.g. reniform, root-knot, and sting) or an old citrus orchard (old citrus orchards are often infested by regulated citrus nematode pests). A site that is not sufficiently elevated and prone to be flooded by water from ponds or canals should also be excluded. These types of sites can be readily contaminated with nematodes that are transported passively in flood water from infested areas. The selected site should also be protected from strong winds which are known to transport some nematode species.

Figure 1. Photo of an unpaved windrow composting operation prone to contamination by soil-borne plant-parasitic nematodes and pathogens from runoff water between the windrows and from the machinery adding composting amendments to the windrows. Some regulated nematodes such as the burrowing, citrus, and reniform nematodes are shown in the icons.

After an appropriate site is selected, the facility should be designed to prevent the introduction and spread of nematodes during composting operations. Common planning errors include:

• Close vicinity of the dump site to the composting and storage areas may result in the composting material and stored compost being contaminated with raw material, which may contain live nematodes. It is desirable that the incoming raw material dump site be established a minimum of 100 ft from the composting and storage areas.

• Improper leveling of the dump site can allow nematode movement with flowing water from the


dump site into the composting and storage areas. It is desirable that a drainage ditch at least 2-ft deep or a solid wall at least 2-ft high encompass any portion of the dump site facing the composting and storage areas.

• Poor weed control. Many weeds in a dump site are hosts of restricted nematodes and may unknowingly contaminate the other areas of the operation. The dump site must be kept free of weeds by using appropriate herbicides or mechanical methods.

• A shredder grinder (hammer mill) in close vicinity to the composting and storage areas can cause nematode contamination from blowing shredded raw material into the composting or finished product. The shredder grinder should be close to raw material and a minimum of 100 ft from composting and storage areas.

• Inappropriate handling of the shredded raw material containing live nematodes can cause contamination of the composting and storage areas. Precautionary measures should be taken during the transport of the shredded raw material to the receiving site to begin the composting process. The equipment moving the new ground raw material should operate at least 40 ft away from the material already undergoing the composting process.

• Nematode-contaminated machinery used to turn piles may reintroduce nematodes into the composted piles. Equipment must be kept free of debris from other sources or cleaned after each operation. If possible, equipment should be divided into groups according to the stage of the composting process. There should be one set of equipment used to handle and move only raw materials and another set to handle and move the composted finished product. The equipment (bucket loaders) used to handle raw material and finished material should never be in close proximity to one another nor should their working area overlap. There should also be intermediate equipment used only for the turning and aeration of the windrows. Machinery used for turning and aerating the windrows (windrow turners) should start with the oldest (composted) material and work towards the newest (raw) material in order to prevent contamination of composted product with the fresh, infected and partially composted organic material. Once the turning equipment has completed the cycle from the oldest to newest material, it should be thoroughly decontaminated by washing before it returns to the oldest material.

• Unsanitized vehicles can disseminate nematodes in the composting operation. Nematodes can be disseminated by soil and debris clinging to tires and adhering to vehicle parts. Vehicles transporting raw material to the dump site and to the hammer mill or to the receiving composting area to initiate the composting process may also be contaminated with nematodes which adhere to debris clinging to the vehicles and thus readily spread to the composting and storage areas. Precautionary measures should be taken in order to ensure that unsanitized machinery does not enter either into areas with ongoing composting or the storage area. Nematode-contaminated vehicles can be disinfected by hosing down their surfaces with high water pressure or by steam hosing. The use of bleach is effective, but it may cause corrosion of the treated vehicle surfaces.

• The finished product can easily be contaminated with nematodes if it is stored in a site subject to flooding or located in the vicinity of nematode contamination sources, such as the dump site. The storage area should be protected from any

• As noted above, a composting area subjected to run-off water from the surrounding areas or located in the vicinity of the dump site may be contaminated by nematodes, which can end up in the finished product. Standing water causes undesirable fermentation processes in the piles and can transport nematodes from the piles

containing raw material at the beginning of the composting process to the piles which have completed the process. The composting area should be protected from any source of contamination and located in an elevated site on a concrete slab appropriately sloped to favor drainage from the windrows and to prevent anaerobic conditions during the composting process. The land around the composting area should be kept free of weeds. Irrigation water should come from wells or from ponds free of weeds around their banks.

• Nematode-contaminated vehicles used to move the finished product from the composting areas to the storage area may contaminate the finished product with nematodes. Vehicles designated to transport the finished product from the composting area to the storage site should be used only for this purpose and never be allowed to enter into an area contaminated with nematodes.


Figure 2. A flow chart summarizing the phytosanitary measures that should be taken into consideration for the construction of composting facilities for the production of plant-parasitic nematode-free mulches that will conform to standard necessary for nematode certification.

• source of contamination and located in an

elevated site on a concrete slab appropriately sloped to prevent contact of the finished product with run off water.

• Turners and front end loaders and/or trucks used for transport of raw material should be sanitized in an appropriate area before they are used to transport stable composted material to the storage area. This site should be elevated, paved, properly sloped to avoid run-off water flowing into composting and storage areas, and located a minimum of 100 ft from composting and storage areas. The sanitizing station should be located closer to the dump site than the composting and storage areas. However, separate sets of front end loaders should be used for the transport of raw material and stable compost.

• Untrained employees can contaminate the finished product by unknowingly using contaminated equipment and by not understanding sanitation practices. Verbal instructions and signs should be posted alerting employees of the precautionary measures that should be adopted during the different phases of the composting process. Employees should be instructed on the importance of good sanitation practices to avoid contamination problems.

The flow charts in Figures 2 and 3 summarize the phytosanitary measures that should be taken into consideration for the construction of composting facilities and during the composting process.

Suggested phytosanitary measures to be taken into consideration for the construction of composting

facilities.

Dump site Sanitizing station

Composting area

Storage area

Dump site should be free of regulated

nematodes, properly sloped, surrounded

by a ditch to prevent overflow of run- off water from the dump site and located a minimum of 100 ft from the

composting and storage areas.

Composting area should be

properly sloped, elevated and

paved to avoid standing water

around the piles and contamination

with run-off water from the

environs.

Storage area should be properly sloped, elevated and paved

to avoid contamination with run-off water from

the environs.

It is desirable that separate sets of

front- end loaders and trucks for

transport of raw material and stable compost are used.

However. an area in the facility should be designated for

sanitizing vehicles (turners, front-end loaders and trucks). This area should be properly sloped and paved to prevent

run-off water into the composting and storage areas and

located a minimum of 100 ft from these

two areas.

/ ....,

'-. ~

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Suggested phytosanitary measures to insure a quality composting process.

Dump site

Hammer mill

Vehicles for

transport of raw material from the dump site to the

composting area

Composting piles

Vehicles for

transport of stable compost

Storage area

It should be kept free of

weeds harboring

nematode plant pests. The drainage

ditches around the dump site

should be appropriately maintained to avoid overflow

of run-off water into the composting and storage areas.

Locate it close to the dump site

and away (a minimum of

100 ft) from composting and storage

area.

Use these vehicles for transport of raw material

only. Sanitize them for

other use. These

vehicles are a major

source of contamination

of stable compost.

In the composting area there should be a

set of equipment to

handle the raw material and

another set to handle the

stable compost.

Machinery used to turn the piles should

start from the oldest

material toward the

newest. Turners should be sanitized

before returning to the oldest.

Use sanitized vehicles only to

transport stable compost from the

composting to the storage area.

Only sanitized vehicles should

enter this area. This area

should be protected from contaminants.

Figure 3. A flow chart summarizing the phytosanitary measures that should be taken into consideration during the composting process for the production of plant- parasitic nematode-free mulches that will conform to standard necessary for nematode certification.

The establishment of a well-designed composting facility and the implementation of appropriate composting and sanitation procedures are both costly and labor intensive. Typically, such facilities will need to be subsidized, as the up-front costs of a properly designed and operated facility cannot be recouped by the sale of finished stable product. However, these practices will pay for themselves in the final analysis by ensuring the production of high quality nematode-free compost product and lower management cost of plant production.

The sanitation guidelines provided in this paper were prepared for facilities adopting the windrow composting method, which is the most common in Florida. The in-vessel composting method has been adopted only by two Florida counties (Palm Beach [Solid Waste Authority of

Palm Beach County] and recently by Sumter [Sumter County Solid Waste, Recycling, and Composting Facility

“Paradise”]). The risk of contamination of the composting material with nematodes from the environment during the composting process is almost negligible in these in-vessel composting facilities. However, improper handling and storage of the compost material can occur also in these facilities; therefore, in-vessel facilities should implement the same sanitation procedures listed previously for the windrow composting facilities.

REFERENCES

Esser, R. P. 1979. Nematode entry and dispersion by water in Florida nurseries. Florida Dep. of Agric. & Consumer Services, Div. of Plant Industry, Gainesville. Nematology Cir. No. 54. 2 p.

Esser, R. P. 1980. Nematode entry and dispersion by man and animals in Florida nurseries. Florida Dep. of Agric.

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& Consumer Services, Div. of Plant Industry, Gainesville. Nematology Cir. No. 60. 2 p.

Esser, R. P. 1984. How nematodes enter and disperse in Florida nurseries via vehicles. Florida Dep. of Agric. & Consumer Services, Div. of Plant Industry, Gainesville. Nematology Cir. No. 109. 2 p.

Esser, R. P. 1996. Sanitation practices to control plant parasitic nematodes in Florida plant nurseries. p. 63-98. In D. Rosen, F.D. Bennett, and J.H. Capinera, eds. Pest Management in the Subtropics, Integrated Pest Management – a Florida Perspective. Intercepted Ltd., UK.

Hoitink, H. A. J., Y. Inbar, and M. J. Boehm. 1991. Status of compost-amended potting mixes naturally suppressive to soilborne diseases of floricultural crops. Plant Dis. 75:869-873.

Lehman, P. S. 1980. Weeds as reservoirs for nematodes that threaten field crops and nursery plants. Florida Dep. of Agric. & Consumer Services, Div. of Plant Industry. Nematology Cir. No. 66. 2 p.

Metting, F.B. 1993. Soil microbial ecology. Application in agricultural and environmental management. Marcel Dekker, Inc., New York. 646 p.

Natural Resource, Agriculture, and Engineering Service (NRAES). 1992. On-Farm Composting Handbook (R. Lynk, ed.). NRAES, Coop. Ext., Ithaca, NY 14853-5701. 186 p.

Noble, R., and S. J. Roberts, N. R. 2004. Eradication of plant pathogens and nematodes during composting: a review. Plant Path. 53 (5):548-568.

Ozores-Hampton, M., and D.R.A.Peach. 2002. Biosolids in vegetable production systems. HortTech. 12(3):18-22.

Ozores-Hampton, M., T. A. Obreza, and G. Hochmuth, 1998. Using composted wastes on Florida vegetables crops. HortTech. 8(2):130-137.

Rathje, W. L. 1991. Once and future landfills. National Geographic 179(5):116-134.

U. S. Environ. Protection Agency (USEPA). 1994. A plain English guide to the EPA part 503 biosolids rule. EPA832-R-93-003. September. Washington, DC: USEPA, Office of Wastewater Management. 176 p.


Agronomic Impact of Water Treatment Residual Co-applied with Phosphorus Sources to Florida Sands

Olawale O. Oladeji, Jerry B. Sartain*, and George A. O’Connor

ABSTRACT

Aluminum-rich water treatment residuals (WTR) are being suggested as amendments to immobilize excessive P in Florida soils that sorb P poorly. One of the negative impacts of land application of WTR could be excessive P immobilization that can reduce plant available P. This study evaluated the influence of application rates of WTR and various P-sources on soil and plant available P. In a glasshouse study, bahiagrass (Paspalum notatum Flügge) and ryegrass (Lolium perenne L.) were grown sequentially in a P-deficient top soil of (Immokalee sand [sandy, siliceous, hyperthermic Arenic Alaquods]) amended with four sources of P at two application levels (N- and P-based rates) and three WTR rates (0, 1 and 2.5% oven dry basis). Soils were sampled at planting of each grass and were tested for water extractable P (WEP), iron strip P (ISP), Total recoverable P (TP), and degree of P saturation (DPS). Plant dry matter (DM) accumulation and P uptake were also determined. Soil soluble P as measured by WEP and ISP, was reduced by WTR application. Phosphorus sorption capacity of the sand was improved by more than 75% by applying 2.5% WTR, and DPS reduced below 25% threshold value suggested for Florida soil. Co-applied WTR to N-based rate treatment reduced soil soluble P at planting of each plants, but plants DM yield was not reduced below that observed at P-based rate without WTR treatment. Ryegrass DM accumulation was similar for treatments with and without WTR, but P uptake was reduced with WTR. Thus, WTR has potential to improve P sorption capacity of Florida sand and reduce P loss to the environment with little or no reduction in plant growth, but plant P uptake may be affected.

INTRODUCTION

Land application of residuals such as biosolids is supported by USEPA 40 CFR Part 503 (USEPA, 1995) and other environmental agencies worldwide as long as they are applied at agronomic rates based on crop N-requirements (N-based). The N-based application of manures and biosolids usually supplies P to soil in excess of that removed by plants. The excess P accumulates in the soil (Pierzynski, 1994; Maguire et al., 2000), and is subject to offsite migration to surface water.

Phosphorus pollution of waters is a major concern in Florida because P is the limiting nutrient for eutrophication of most freshwaters (Elliott et al., 2002). The low-P retention capacities of Florida soils coupled with the characteristic flat topography and interception of shallow ground waters by discharge system favors the eventual entry of leached P to surface water bodies. Thus, control of

soluble P present in residuals and manure impacted soils is very important in Florida.

Recent work (Brown and Sartain, 2000; O’Connor and Elliott, 2001; O’Connor et al., 2002) has shown that various WTRs can be effective soil amendments in controlling soluble P. O’Connor and Elliott (2001) co-applied an Al-treated water treatment residuals (Al-WTR) with several biosolids, fertilizer, and two manures and demonstrate complete control of P leaching through Florida sands regardless of P-source applied. Land application of WTR has reduced soil soluble P from manure (Peter and Basta 1996; Cox et al., 1997) and biosolids (Ippopolitto et al., 1999) applications.

Aside from P solubility control, other potential benefits of WTR land application are increased plant nutrient availability (e.g., nitrogen and total organic C) (Lin, 1988; Dempsey et al., 1989; Elliott et al., 1990; Elliott and Dempsey, 1991) and increased aggregate stability, water retention, aeration, and drainage capacity (El-Swaify and Emerson, 1975; Rengasamy et al., 1980; Bugbee and Frink, 1985). The amorphous hydrous oxides in WTR also can also increase cation exchange capacity of coarse-textured soils (American Society of Civil Engineers et al., 1996).

Potential disadvantages of land applied Al-WTRs include excessive immobilization of plant-available soil P and Al toxicity. The high P-fixing capacity reported in soil amended with WTR (O’Connor et al., 2002; Dayton et al., 2003) is similar to Andisols (phosphate retention of 85%) and can limit crop growth (Molina et al., 1991). Heil and Barbarick (1989) noted severe P-deficiency symptoms associated with an excessive rate (25 g WTR kg-1) of WTR addition to soil planted to sorghum-sudangrass [Sorghum bicolor (L.) Moench - Sorghum x drummondii (Steudel) Millsp. Chase]. Ippolito et al. (1999) decreased P concentrations in blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] by increasing WTR rates. Rengasamy et al. (1980) reduced P uptake in maize (Zea mays L.) with WTR addition, while Elliott and Singer (1988) and Bugbee and Frink (1985) found reduced P concentrations in tomato (Lycopersicon esculentum L.) and lettuce (Lactuca sativa L.) grown in WTR-amended potting media. To enhance the environmental benefit of land applied WTR without negative agronomic impact, this study evaluated the impact of P-sources and WTR co-applied to Florida sands on plant P uptake and yield.

Olawale O. Oladeji, Jerry B. Sartain, and George A. O’Connor, Soil and Water Science Dep., P.O. Box 110510, Univ. of Florida, Gainesville, FL 32611-0510

*Corresponding author ([email protected]). Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:38-48 (2006)




Top soil (0-15 cm) of an Immokalee sand (sandy, siliceous, hyperthermic Arenic Alaquods) used for the glasshouse experiments was collected from Okechobee, FL. Four sources of P were applied and included a high water soluble-P, Boca Raton biosolids and medium water soluble-P, Pompano biosolids, which were chosen to represent spectrum of biosolids that might be land-applied. The third source, poultry manure, was obtained from Tampa Farms in Indiantown, FL. The operation is representative of large egg-laying operation. The final source was triple super phosphate (TSP), which is a typical mineral P-source applied to Florida crops. Each of the P-sources was applied at two rates (N- and P-plant requirement based), and these treatments further received WTR treatments at three rates (0, 10 and 25 g kg-1 oven dry basis). Thus, the study was a 4x2x3 factorial experiment with one control and arranged in RCB design with three replicates.

The bulk soil was air-dried, thoroughly mixed, sieved (<2 mm) prior to analysis. Both the soil and the amendments were analyzed for Total P, Fe, Al, Ca, and Mg by ICAP following digestion according to the EPA Method 3050A (USEPA, 1986). Oxalate extractable P, Fe, Al, Ca, and Mg were determined by ICAP after extraction at a 1: 60 solid: solution ratio, following the procedures of Schoumans (2000). Total C and N of the amendments were determined by combustion at 1010 °C using a Carlo Erba NA-1500 CNS analyzer. Reaction (pH) was determined on fresh materials (1:2 solid or soil: solution ratio). Percent solids were determined by drying materials at 105 °C (Sparks, 1996).

Weight of P-sources to provide the equivalent of 44 kg total P ha -1 (P-based application rate) and 179 kg plant available nitrogen (PAN) ha-1 (N-based waste application rate) recommended by Kidder et al. (2002), were calculated from the total P and N contents. Mineralization rates of 40% of total N in biosolids and 60% of total N in manure were assumed, based on previous experience in similar studies (O'Connor and Sarkar, 1999; O'Connor et al., 2004). The P supplied by the N-based rate treatments varied with P-sources. Since the idea of the WRT treatments was to fix the P supplied at the P-based rate treatment, twice the P applied in the P-based rates (88 kg total P ha -1) was applied as TSP N-based rate treatment. All treatments, including the control, received the same amount of N as NH4NO3 in split applications (monthly) at planting of bahiagrass only. Potassium-magnesium sulfate ("Sul-Po-Mag": 22% S, 18% K, and 11% Mg) equivalent to 444 kg ha -1 (1.8 g) was added to each treatment to provide adequate and uniform S, K, and Mg..

Soil (8.5 kg) and appropriate amounts of the amendments were weighed and thoroughly mixed. Water was added to bring the mixture to field capacity, and the samples were allowed to equilibrate for one week with

daily mixing. Samples of the soil were taken after equilibration (1 week) for analysis (Time zero samples)

The remaining soil were packed to a bulk density of 1.3 Mg m-3 into a 20-cm diameter, 21 cm deep pot (6.5 liters) and planted with bahiagrass at a depth of 3 mm and seeding rate of 7 g per pot. The soil surface of each pot was covered with moist filter paper, which was wetted and kept moist daily until seed germination. After germination the filter papers were removed and soil wetted daily and moistened to initial weight once weekly. There was non-uniform germination despite the careful nurturing described which resulted in thin plant stands in some pots and the missing areas of the pots were reseeded after one week. Because of the problems encountered during establishment of the plants, the first harvest was done 36 days after removing the filter papers, whereas subsequent harvests occurred monthly. Harvest was at a height of 5 cm above the soil surface with scissors or electric clippers. Grass samples were dried to constant weight at 65 oC to determine DM. After each harvest, the pots were weighed and watered as necessary after adding the supplemented N (split applied) to return to initially determined pot weights. The pots within blocks were shifted by a position twice weekly to further reduce positioning advantage in the glasshouse.

Bahiagrass was harvested four times. After DM determination, dried material was ground in a Wiley mill with stainless steel blades to pass a 20-mesh sieve and stored in airtight polyethylene containers. Ground plant material was ashed, treated with 6N HCl, and brought to final volume with distilled water as described by Plank (1992). Phosphorus in the diluted digests was determined colorimetrically (Murphy and Riley, 1962). The plant uptake (kg P ha-1) was obtained as the product of P concentration and dry matter weights. Weighted means of the plant P concentrations were obtained by dividing the total P uptake by the total dry matter weight.

After the final bahiagrass harvest, soil samples were taken from the center of each pot using an auger of 5-cm diameter, and the hole created filled with time zero soil preserved for that purpose. Each pot was then planted with ryegrass (3 g seed pot-1), a cool season grass, to evaluate the residual effects of the amendments. Thus, no further P-source was applied and soil obtained after the final bahiagrass harvest served as time zero soil for the ryegrass cropping.

Ryegrass was harvested three times (approximately monthly) and crop management was the same as for bahiagrass except that treatments were applied only during planting of bahiagrass. The time zero soil samples for each grass and at each harvest date of the ryegrass were all analyzed for pH and electrical conductivity (1:2 solid: solution), total recoverable P, Al and Fe (USEPA, 1986) and 0.2M oxalate extractable P, Al and Fe (Schoumans,


2000). Other parameters determined in the soils included Mehlich-1 P, WEP and ISP.

Water extractable P was determined by shaking the soil samples with deionized water at a ratio of 1: 10 soil: solution ratio for one hour (Sharpley with Moyer, 2000). The P concentration in the extract was analyzed by colorimetry using the Murphy and Riley method (1962). Mehlich 1-P (M 1-P) was determined on the samples by shaking of the soil samples for 5 min with 0.0125 M H2SO4 in 0.05 M HCl solution at a ratio of 1:4 soil:solution ratio (Hanlon et al., 1997). Extractants were filtered through Whatman No 42 filter paper and analyzed colorimetrically with the Murphy and Riley method (1962). The Iron-strip P was determined by reacting the soil samples with Fe-impregnated (0.65 M FeCl3 in 0.6 M HCl) filter paper and then extracted the P adsorbed with 0.1 M H2SO4 (Van der Zee, 1987). The extractable P was analyzed colorimetrically with the Murphy and Riley method (1962).

Standard QA/QC protocols were observed during the sample collection, handling and chemical analysis. For each set of samples during chemical analysis, a standard curve was constructed (r2 > 0.998). Method reagent blanks were appropriately used, as well as certified standards from a source other than normal calibration standards. A 5% matrix spike of the set was used to determine the accuracy of the data obtained and another 5% of the set was used to determine the precision of the measurements (duplicates). Analyses that did not satisfy the QA/QC protocol were rerun.

STATISTICAL ANALYSIS

Normal probability plots and residuals of the data were studied to ensure the samples satisfied the assumptions of normality, constant variance and independence. Analysis of Variance (ANOVA) was performed on DM yield, P concentrations, and P uptake of bahiagrass and ryegrass, and also on varying soil P measured in samples taken at planting of each grass using PROC GLM (SAS Institute, 1999). The data were analyzed without control treatment as a RCBD using the model: Yijkl = µ + αi + βj + γk + αβij + αγik + βγjk + αβγijk + εijkl; where αi is effect of ith P-source (i = manure, Boca Raton biosolids, Pompano biosolids, and TSP); βj effect of jth source rate (j = P-, and N-based rates); γk effect of kth WTR rate (k = 0, 1, and 2.5 %) and other terms are the 2-way (αβij, αγik, and βγjk), and 3-way (αβγijk) interactions, and error (εijkl) terms. The plants data and soil TP and ISP are involved in WTR-P-source rate interaction. Thus, to compare the P-source and WTR rate combinations and the control, the 7 treatments (N-based + 0% WTR, N-based + 1% WTR, N-based + 2.5% WTR, P-based + 0% WTR, P-based + 1% WTR, P-based + 2.5% WTR, and control) were reanalyzed using one factor (treatment) model: Yij = µ + αi + εij; where αi is effect of ith treatment and εij is the

error terms. When significance was indicated by ANOVA, means were separated by either single degree of freedom contrast procedures or Tukey method. All statistical analysis tests were done using a significance level of 5%.

RESULTS AND DISCUSSIONS

Soil and Amendments Properties

The native soil (Table 1) has low extractable P (M-1P, WEP and ISP). Soil M-1P of <10 mg kg-1 is considered very low for agronomic crops including bahiagrass (Kidder et al., 2002). The low P status made the soil suitable for the phosphorus response experiment, and for testing impacts of different P-sources and WTR application rates. Plant response to the added P and other treatments should be easily identified in an initially P deficient soil. The pH 5.5 coincides with the so-called “target” pH for bahiagrass, thus, making it suitable for the growth of bahiagrass (Hanlon et al., 1990).

Table 1. Selected properties of Immokalee soil used. Parameters Value pH 5.5 Electrical conductivity, us cm-1 323 C, g kg -1 12.0 ±0.1†

Mehlich 1-P, mg kg -1 6.40 ±0.35 Water extractable P, mg kg -1 2.88 ±0.19 Fe-strip-P, mg kg -1 3.11 ±0.48 Total P, mg kg -1 24.5 ±2.1

Total Al, mg kg -1 88.0 ±4.0 Total Fe, mg kg -1 107 ±20 Total Ca, mg kg -1 449 ±8 Total Mg, mg kg -1 36.0 ±3.0 Oxalate P, mg kg -1 22.6 ±1.6 Oxalate Al, mg kg -1 49.8 ±3.6 Oxalate Fe, mg kg -1 96.0 ±5.3 Oxalate Ca, mg kg -1 34.8 ±2.5 Oxalate Mg, mg kg -1 20.4 ±1.8 † Means of three samples ± standard deviation.

All organic sources of P used had pH of ~7.6 (Table 2); whereas the Al-WTR is acidic (pH of 5.6) and dominated by Al (157 g kg-1), more than 90% (145 g kg-1) of which is amorphous (0.2M ammonium oxalate extractable; McKeague et al., 1971). Total P and N were greatest in Boca Raton biosolids and least in poultry manure. Total and Oxalate Al and Fe were lower in manure than in the two biosolids, but Ca concentration in the manure was greater than in the biosolids. The greater Ca in manure could be due to the Ca-rich additives common to poultry feed, a large part of which end up in the manure. The greater oxalate P (Pox) and smaller Oxalate Fe (Feox) and Al (Alox) resulted in greater P saturation index (PSI) of Boca Raton biosolids (1.44) than in Pompano biosolids (0.7). The PSI>1 indicates excess P beyond the materials P retention capacity and agrees with the greater water soluble P in Boca Raton biosolids than in Pompano biosolids.


Table 2. Selected chemical properties of P-sources and Al water treatment residual (Al-WTR) used. P-Source Properties

Chicken Manure Boca Raton Biosolids Pompano Biosolids TSP‡ Al-WTR

pH 7.7 7.6 7.6 5.9 5.5 C, g kg-1 32.0 34.7 36.6 - 19.9 N, g kg-1 27.0 ± 0.3† 50.4 ± 0.4† 43.1 ± 0.6† - 0.7 Solids, % 25.1 ± 0.1† 13.4 ± 0.0† 15.4 ± 0.1† 100 62.5 ± 2.2†

WEP§, g kg-1 4.57 ± 0.16† 5.52 ± 0.18† 1.16 ± 0.08† 175 - Total P, g kg-1 25.3 ± 0.3† 47.3 ± 2.3† 26.2 ± 0.2† 209 4.6 ± 0.7†

Total Al, g kg-1 0.90 ± 0.10† 9.30 ± 0.40† 9.20 ± 0.40† 10.0 157 ± 3†

Total Fe, g kg-1 1.50 ± 0.10† 24.3 ± 0.8† 32.8 ± 0.4† 15.7 6.0 ± 0.1†

Total Ca, g kg-1 102 ± 3† 27.5 ± 1.1† 47.0 ± 0.5† 137 1.5 ± 0.1†

Total Mg, g kg-1 5.80 ± 0.20† 10.0 ± 0.5† 4.10 ± 0.10† 6.2 0.40 ± 0.02†

Oxalate Ca, g kg-1 0.04 ± 0.00† 0.06 ± 0.0† 0.05 ± 0.0† - 0.33 ± 0.01†

Oxalate Mg, g kg-1 4.20 ± 0.10† 9.70 ± 0.00† 3.70 ± 0.20† - 0.36 ± 0.01†

Oxalate P, g kg-1 12.7 ± 0.0† 34.0 ± 0.9† 20.4 ± 0.1† 186 4.3 ± 0.0†

Oxalate Fe, g kg-1 0.70 ± 0.00† 19.4 ± 0.5† 24.7 ± 0.2† 11.0 5.1 ± 0.0†

Oxalate Al, g kg-1 0.20 ± 0.00† 8.90 ± 0.60† 9.20 ± 0.00† 6.9 145 ± 0.4†

PSI¶ - 1.44 ± 0.02† 0.70 ± 0.02† - 0.02 ± 0.0†

†Means of three samples ± standard deviation. ‡ Triple super phosphate. §Water extractable P. ¶Phosphorus Saturation Index = [(0.2M oxalate P, in moles) / (oxalate Fe, in moles + oxalate Al, in moles)].

Table 3. Effects of P-source, source rate, and water treatment residuals (WTR) rate on water extractable P, mg kg-1 of soil sampled at planting of bahiagrass.

-------------Rate----------- Source WTR rate / Contrasts N-based P-based

Contrast N- vs P-based

0 % 18.9† 6.57 * 1 % 11.5 3.76 * 2.5 % 5.99 2.95 * Linear effect * *

Manure

Quadratic effect * * 0 % 41.5 6.74 * 1 % 20.9 4.02 * 2.5 % 15.5 2.86 * Linear effect * *

Boca Raton biosolids

Quadratic effect * * 0 % 6.58 4.16 * 1 % 3.99 2.81 NS 2.5 % 2.86 2.19 NS Linear effect * NS

Pompano biosolids

Quadratic effect * NS 0 % 19.6 12.4 * 1 % 8.65 3.90 * 2.5 % 4.12 2.18 NS Linear effect * *

TSPP

‡

Quadratic effect * * Manure vs Biosolids * NS Organic vs Mineral source * * Contrast at 0% WTR Boca Raton vs Pompano * * Manure vs Biosolids * NS Organic vs Mineral source * NS Contrast at 1% WTR Boca Raton vs Pompano * NS Manure vs Biosolids * NS Organic vs Mineral source * NS Contrast at 2.5% WTR Boca Raton vs Pompano * NS

† Means of three samples. ‡ Triple super phosphate. * Significant at p = 0.05; NS = not significant.

Soil Phosphorus

The soil samples taken at planting of bahiagrass and ryegrass show WEP was affected by the sources of P, P-source rate, and WTR rates (Table 3 and 4). At bahiagrass planting, soil WEP values were greater at N-based than at P-based rate regardless of WTR rate for the manure and Boca Raton biosolids treatments (Table 3).

However, similar WEP values were observed for both the N- and P-based rate of Pompano biosolids treatment at 1% and 2.5% WTR, and at 2.5% when treated with TSP. The similar WEP values probably resulted from the reduced water soluble P nature of the pompano biosolids in addition to sorption by WTR. The greater solubility of TSP makes the P assessable to sorption; hence, applying WTR at 2.5% resulted in similar WEP values of the two application rates of TSP treatment (Table 3).


Table 4. Effects of P-source, source rate, and water treatment residuals (WTR) rate on water extractable P, mg kg-1 of soil sampled at planting of ryegrass. Rate Source WTR rate / Contrasts

N-based P-based Contrast

N- vs P-based 0 % 11.5† 8.47 * 1 % 5.08 2.23 * 2.5 % 3.37 1.90 NS Linear effect * *

Manure

Quadratic effect * * 0 % 21.7 4.43 * 1 % 6.51 1.43 * 2.5 % 3.65 1.17 * Linear effect * NS

Boca Raton biosolids

Quadratic effect * * 0 % 9.04 5.14 * 1 % 6.67 1.40 * 2.5 % 3.88 1.26 * Linear effect * *

Pompano biosolids

Quadratic effect NS * 0 % 11.4 8.61 * 1 % 4.45 4.60 NS 2.5 % 4.19 4.67 NS Linear effect * *

TSPP

‡

Quadratic effect * * Manure vs Biosolids * * Organic vs Mineral source * * Contrast at 0% WTR Boca Raton vs Pompano * * Manure vs Biosolids NS NS Organic vs Mineral source NS * Contrast at 1% WTR Boca Raton vs Pompano NS NS Manure vs Biosolids NS NS Organic vs Mineral source NS * Contrast at 2.5% WTR Boca Raton vs Pompano NS NS

†Means of three samples. ‡Triple super phosphate *Significant at p = 0.05; NS = not significant

In general, increasing WTR rate reduced WEP regardless of P-source or P-source application rate as shown by the observed linear and quadratic effects of the WTR rates (Table 3). The only exception to this was Pompano biosolids treatments, which exhibited similar soil WEP values at different WTR rates for the P-based rate treatment. When WTR was not applied, soil WEP values differed for the different P-sources with TSP > the organic sources treatments, and Boca Raton biosolids > Pompano biosolids treatments. The trend reflects the solubility of the P-sources. However, similar WEP values were observed for the different sources when WTR was applied, indicating P-source solubility was masked by WTR applications. For the N-based rate treatment, soil WEP values differed with biosolids > manure treatments, Boca Raton biosolids > Pompano biosolids treatments, and TSP >organic source treated soils at each levels of WTR.

The WEP values of soils sampled at planting of ryegrass differed in trend from the time zero WEP values (at planting of bahiagrass). When the ryegrass was planted, WEP in manure-amended soils was similar for the two rate treatments (N- and P-based) at 2.5% WTR (Table 4). In contrast, for the P-based rate treatment of the Boca Raton biosolid, sorption of P by the WTR resulted in similar WEP values regardless of WTR rate, both of which were lower than when no WTR was applied. For the N-based rate treatment, variation in solubility of the different P-sources was masked by WTR and resulted in the similar

WEP values observed for the different P-sources. In the absence of WTR, WEP values for Boca Raton biosolids-treated soils remained greater than manure- and Pompano biosolids-treated soils at planting of ryegrass. Also for the P-based rate treatment, organic-source-treated soils had lower WEP values than TSP-treated soils which could result from less mineralization of the organic P-sources than assumed. Another change observed in the trends of WEP values with time was in Pompano biosolids treatment at the P-based rate. In contrast to what was found at planting of bahiagrass, as at when ryegrass was planted, WEP was lower for the Pompano biosolids WTR treatments than untreated at P-based rate.

In general, soil WEP was lower for P-based than N-based rate treatments and lower in presence, than absence of WTR. The effect of the sources only exists when the sources were applied at N-based rate without WTR at planting of ryegrass. In the presence of WTR, similar WEP values were observed for N-based rate treatment.

The M-1P values of soil sampled at planting of bahiagrass did not differ due to WTR rates for the P-based rate treatment (Table 5). The similar soil M-1P values for the P-based rate treatment were due to the solubilizing effect of the acidic extractant on the sorbed P (Table 5). However, because of the differences in the initial P load of the two rates, M-1P was greater at N-based rate than at P-based rate at each of the three levels of WTR.


Table 5. Effects of application rates of P-sources and water treatment residuals (WTR) rate on Mehlich-1P, mg kg-1 of soil sampled at planting of Bahiagrass. Rate WTR rates and their Polynomial effect


N- vs P-based 0 % 85.2† 19.9 * 1 % 79.6 23.3 *

2.5 % 80.8 28.3 * Linear * NS

Quadratic NS NS †Means of twelve samples. *Significant at p= 0.05; NS - not significant.

Table 6. Effects of P-sources and application rates on Mehlich-1P, mg kg-1 of soil sampled at planting of bahiagrass and ryegrass. Rate Time of sampling Sources of P and their contrasts


N- vs P-based Manure 67.4† 23.1 * Boca Raton 153 26.8 * Pompano 65.3 21.3 * TSPP

‡ 41.9 24.2 * Manure vs. Biosolids * NS Organic vs Mineral source * NS

At bahiagrass planting

Boca Raton vs. Pompano NS NS Manure 67.0 16.1 * Boca Raton 73.4 14.6 * Pompano 50.2 12.9 * TSP 17.7 12.5 * Manure vs. Biosolids * NS Organic vs Mineral source * NS

At ryegrass planting

Boca Raton vs. Pompano * NS †Means of three samples. ‡Triple super phosphate *Significant at p = 0.05; NS = not significant

Greater soil M-1P for the N-based rate than the P-based rate treatment was observed at planting of the two grasses irrespective of the sources of P applied (Table 6). For the P-based rate treatment, M-1P values also were similar regardless of sources because similar amounts of added P with that rate. However, the M-1 P values were variable for the N-based rate treatment due to different concentration of P in the different P-sources. The P added as the N-based rate for TSP (88 kg ha-1) was smaller than the P loads from other sources (280 kg ha-1 from Manure, 370 kg ha-1 from Boca Raton biosolids and 233 kg ha-1 from Pompano biosolids).

Effects of the P-rate and WTR combinations along with control treatment on soil bioavailable P (as measured by ISP), and P loads (as measured by total recoverable P) are summarized in Fig. 1. Soil ISP is a measure of bioavailable P, reportedly estimating the total amount of P available for plant uptake within a growing season (Van Noordwijk et al., 1990, Koopmans et al., 2004). Across P-source, both time zero soil (planting of bahiagrass) and soil samples taken at planting of ryegrass show similar trends in the soil ISP values with WTR rate. Similar to the WEP, the ISP values were reduced with increasing WTR rates (Fig. 1a) and established the capability of WTR to reduce soil soluble P and hence P loss. At 2.5% WTR rates, the ISP of N-based rate treatment was greater than at P-based rate treatment without WTR. This implies the hazard of excess soluble P associated with N-based rate treatment could be reduced by applying WTR and at 2.5% WTR applied to N-based rate, the P assessable by the plants is

(a) Soil Iron strip P (ISP)

0

5

10

15

20

25

30

N based (0% WTR)

N based (1% WTR)

N based (2.5% WTR)

Control P based (0% WTR)

P based (1% WTR)

P based (2.5% WTR)

WTR and P-source rates

ISP

(mg

kg-1)

At planting of bahiagrassAt planting of ryegrass

a

bc c

dd d

a

b

cd

ef ef

(b) Soil TP (TP)

0

25

50

75

100

125

150

N based (0% WTR)

N based (1% WTR)

N based (2.5% WTR)


P based (1% WTR)

P based (2.5% WTR)


TP (

mg

kg-1

)

At planting of bahiagrassAt planting of ryegrass

c

ba

ed

f

c

b ba

ed

f

c

Figure 1. Effects of water treatment residual (WTR) rates and P-source rates on (a) iron strip P (ISP) and (b) Total recoverable P (TP) of soil sampled at planting of bahiagrass and ryegrass. Control treatment received neither P-source nor WTR. (Treatments within the same sampling period with same letter are not different at p-value of 0.05 by Tukey test)

still greater than at P-based treatment without WTR. Though the soluble P and bioavailable P measures (WEP and ISP) were reduced with WTR, the increased total recoverable P with WTR (Fig. 1b) established that

■


Table 7. Effects of P-source and water treatment residual (WTR) rates on degree of P saturation (DPS) of soil sampled at planting of bahiagrass and ryegrass. (All DPS values are in %).

WTR Rate Polynomial effect Time of sampling Sources of P and their contrasts 0% 1% 2.5% Linear Quadratic

Manure 103† 33.6 16.0 * * Boca Raton 110 47.5 20.3 * * Pompano 65.4 29.7 16.0 * * TSPP

‡ 96.3 22.9 14.5 * * Manure vs. Biosolids * NS NS Organic vs Mineral source * NS NS

At bahiagrass planting

Boca Raton vs. Pompano * NS NS Manure 65.7 41.7 17.5 * * Boca Raton 47.2 47.6 25.7 * * Pompano 60.1 32.8 18.4 * * TSP 23.3 21.0 13.0 * * Manure vs Biosolids NS NS NS Organic vs Mineral source * * NS

At ryegrass planting

Boca Raton vs Pompano * NS NS †Means of three samples. ‡Triple super phosphate *Significant at p = 0.05; NS = not significant

significant sorbed P is retained in the soil by the added WTR.

Soil Degree of Phosphorus Saturation

The degree of phosphorus saturation (DPS), is a measure of how saturated the soil is with P, and hence is an index of soil capability to hold and prevent losses of P through runoff and leaching. Soils with large DPS values suggest limited ability to retain P. The soil DPS is calculated as percentage of ratio of the soil 0.2 M oxalate extractable P to the corresponding 0.2 M oxalate extractable Fe and Al and assuming an α value of 0.55 for Florida soils (Nair et al., 2004) as:

DPS (%) = [(Pox) / α (Alox+Feox)]*100

where Pox, Alox, and Feox are 0.2M ammonium oxalate extractable P, Al and Fe; all expressed as mmoles.

The DPS values of most soils amended with WTR were reduced below the threshold value of ~ 25% (Fig. 2) recommended for Florida soils (Nair et al., 2004). This is consistent with the soil soluble P measures (WEP and ISP), which were also reduced by the added WTR. Thus, addition of WTR not only reduces the excess P hazards associated with N-based rates, but also improves sorption capacity of low sorbing Florida soils.

The effect of P-source and WTR rate on soil DPS values at planting of bahiagrass and ryegrass are shown in Table 7. At planting of bahiagrass and in the absence of WTR, soil DPS values differed due to P-source; however, with the application of 1 or 2.5% WTR, the effect of the sources was removed and DPS values were similar for the different P-sources. By the time ryegrass was planted, the DPS values of mineral source treatment was further reduced at 1%WTR and differed from those observed in organic source amended soil. However, 2.5% WTR masked the effect of P-sources on DPS throughout the two plantings.

0

25

50

75

100

125

150

175

N based(0% WTR)

N based (1% WTR)

N based(2.5% WTR)

Control P based(0% WTR)

P based (1% WTR)

P based(2.5% WTR)

WTR and P source rates

DP

S (

%)

At planting of bahiagrass (June 04)

At planting of ryegrass (Dec. 04)

a

a

bcb

cd cdbcd

b

ccd cd de d e

Figure 2. Degree of phosphorous saturation (DPS) values of soils samples taken at time zero (planting of bahiagrass) and at planting of ryegrass at the three water treatment residual (WTR) rate and N-based or P-based rate treatments. (Treatments within the same sampling period with same letter are not different at p-value of 0.05 by Tukey test).

Effect of treatments on plants

The reductions of soil WEP and ISP values with addition of WTR reflected in the plant P uptake. The P uptake was reduced with WTR across both N- and P-based rate treatments regardless of P-source applied (Fig. 3). However, the degree of reduction was dependent upon soil P pool as indicated by higher P uptake of the ryegrass for N-based rate treatment with WTR compared to the P uptake observed at P-based rate treatment without WTR. The P-based rate without WTR has adequate nutrients and expected to give optimum plant P.

As soil ISP value is expected to measure bioavailable P (Van Noordwijk et al., 1990, Koopmans et al., 2004), bahiagrass P uptake at each P-source rates and WTR were compared with the ISP values (Table 8). The P uptake by bahiagrass was less than the amount of ISP extracted from the time zero soil for the N-based rate treatment, but greater than the ISP of P-based rate treatment and the control (Table 8). Apparently for the P-based rate

ll!l

El


Table 8. Water extractable P (WEP) and iron strip P (ISP) of soil sampled at planting of bahiagrass and P taken up by bahiagrass (on soil weight basis) for different rates of P-source and water treatment residual (WTR).

Bahiagrass P taken up WEP ISP Change in Total P†

P Rate Treatment WTR rate, % ---------------------- P, mg kg-1 of soil----------------------

Control‡ - 5.49 3.11 3.20 1.52†

0 20.0 21.6 26.8 46.8 1 7.77 11.3 18.2 3.92 N-based

2.5 6.78 7.12 11.3 8.00 0 11.0 7.48 8.42 9.92 1 5.34 3.62 4.64 6.89 P-based

2.5 4.56 2.54 3.45 7.09 † Calculated as: Time zero Total P, mg P kg-1 – Soil Total P, mg P kg-1 after bahiagrass harvest ‡ Treatment without any P-source or WTR applied

0

10

20

30

40

50

N based (0% WTR)

N based (1% WTR)

N based (2.5% WTR)


P based (1% WTR)

P based (2.5% WTR)


P up

take

(kg

ha-1

)

BahiagrassRyegrass

a

c c

db

a

cd

b

b dc d dd

Figure 3. Bahiagrass and ryegrass P uptakes at the three rates of water treatment residual (WTR) and N-based or P-based rate treatments. (Phosphorus uptakes of same plant with same letter are not different at p-value of 0.05 by Tukey test).

(a) Plants dry matter (DM) yields

0

2

4

6

8

N based (0% WTR)

N based (1% WTR)

N based (2.5% WTR)


P based (1% WTR)

P based (2.5% WTR)


DM

yie

ld (M

g ha

-1)

BahiagrassRyegrass

ab

caa a

bcbc cb

bca

b b

(b) P concentrations

0

2

4

6

8

N based (0% WTR)

N based (1% WTR)

N based (2.5% WTR)


P based (1% WTR)

P based (2.5% WTR)


P co

ncen

tratio

n (g

kg-1

) BahiagrassRyegrass

a

c d

b

a

cdc ddd

bbc

d

Figure 4. Bahiagrass and ryegrass (a) dry matter (DM) yields and (b) P concentrations at the three rates of water treatment residual (WTR) and N-based or P-based rate treatments. (Yields or P concentrations of same plant with same letter are not different at p-value of 0.05 by Tukey test).

treatment, the plant was able to remove P from sorbed P pool; however, with sufficient P accessible to the plant at

N-based rate treatment, the sorbed P was not affected by the uptake. Thus the plant was able to access WTR-sorbed P in a situation with insufficient readily available soil P. Change in soil Total recoverable P for N-based rate treatment without WTR was greater than the observed plant P uptake (46.8 vs. 20 mg P kg-1 of soil), which could not be explained. However, at other WTR rates, the Total recoverable P change was similar to the observed plant P uptake (Table 8).

The DM yield of bahiagrass was affected by the WTR treatments (0% WTR > 1% WTR = 2.5% WTR), however ryegrass DM yield was not affected, even at 2.5% WTR. (Fig. 4a). Although the reduction in bahiagrass DM yield may have partly been associated with problems during bahiagrass establishment, reduced bahiagrass DM yield at 2.5% WTR agrees with reduced yield due to P-defficiency reported by Heil and Babarick (1989) in sorghum-sudangrass at 2.5% WTR. The P concentration of both grasses were reduced when WTR was applied (Fig. 4b), and agrees with other studies that shows plants grown in potting media treated with WTR had lower P concentrations (Bugbee and Frink, 1985; Elliott and Singer 1988; Ippolito et al., 1999

Bahiagrass and ryegrass yields were affected by P-sources and their rate as shown on Table 9. For the bahiagrass, there was no difference in yield obtained from organic- and mineral-P-sources treatments at the N-based rate due to sufficient plant available P from all the P-sources. For the P-based rate treatment, the DM yield of bahiagrass was greater from organic P-sources than mineral P-sources, but organic vs. mineral source did not affect ryegrass DM yield. Dry matter yield of both grasses fertilized with the Boca Raton biosolids were greater than in Pompano biosolids treatments for the N-based rate treatment due to greater water soluble P and hence plant available P. However, the DM yields of the two biosolids treatments were similar for P-based rate treatment. The DM yield of ryegrass in manure treatments was greater than biosolids for the P-base rate treatment, but was similar for the N-based rate treatment.

Bahiagrass DM yield was greater at N-based rate treatment than P-based rate treatment for all P-sources, except in manure amended soil. Ryegrass yield was also greater at N-based than P-based rate treatments for all P-

Ill

B

11!1 B

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Table 9. Effects of P-sources and application rates on dry matter yields, Mg ha-1 of bahiagrass and ryegrass. Rate Plant Sources of P and their contrasts


N- vs. P-based Manure 4.55† 6.52 * Boca Raton 7.53 5.97 * Pompano 6.65 5.91 * TSPP

‡ 6.11 5.62 * Manure vs. Biosolids * NS Organic vs Mineral source NS *

Bahiagrass

Boca Raton vs. Pompano * NS Manure 4.38 3.36 * Boca Raton 4.06 2.95 * Pompano 3.75 3.06 * TSP 3.30 3.14 NS Manure vs. Biosolids NS * Organic vs Mineral source * NS

Ryegrass

Boca Raton vs. Pompano * NS †Means of three samples. ‡Triple super phosphate *Significant at p = 0.05; NS = not significant

sources except in TSP treated soil where similar yields were observed for the two rates possibly due to sufficient readily available P at the two rates in TSP treatments.

SUMMARY AND CONCLUSION

With good management, land application of WTR holds potential as a BMP to reduce environmental hazard associated with excess soil P in Florida sands with minimal negative agronomic impact. Phosphorus source and application rate of WTR affected soil water soluble P and ISP values, and this variation could be exploited to arrive at rates with minimal negative impact on the plants. Ryegrass DM yield was not affected by any of the WTR rate tested, but the DM yield of bahiagrass was reduced at the 2.5% WTR.

The P sorption of the sandy Florida soil was improved when WTR was applied. The reduction in soil DPS values was >75% at 1% WTR and higher than that at 2.5% WTR. Reduction of DPS values of soils treated at N-based rate ranged from around 25% to >100% , which shows the ability of WTR to lower the environmental P hazard associated with a N-based rate to below that observed at P-based rate treatment.

This study suggests that potential environmental hazard associated with N-based rate application of P-sources (biosolids, manure and mineral P-sources) can be reduced by use of WTR without measurable negative agronomic impact. As much as 2.5% WTR could be applied with a N-based rate treatment to some crops but less than 1% WTR is advised regardless of treatment rate (N- or P-based) unless higher rates are tested with a specific crop. Applying WTR to P-based rate treatment could reduce plant P concentration, but not below 1g kg-1 expected for pasture grass. Field study is recommended to validate the effectiveness of the residual to reduce P-loss at the recommended WTR rate.

LITERATURE CITED

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Brown, E., and J. Sartain. 2000. Phosphorus retention in United States Golf Association (USGA) greens. Soil Crop Sci. Soc. Florida Proc. 59:112-117.

Bugbee, G.J., and C.R. Frink. 1985. Alum sludge as a soil amendment: Effects on soil properties and plant growth. Connecticut Agric. Exp. Stn. Bull. 823.

Cox, A.E., J.J. Camberato, and B.R. Smith. 1997. Phosphate availability and inorganic transformation in an alum sludge-affected soil. J. Environ. Qual. 26:1393-1398.

Dayton, E.A., N.T. Basta, C.A Jakober, J.A. Hattey. 2003. Using treatment residuals to reduce phosphorus in Agricultural runoff. American Water Works Association Journal. 95 (4): 151-158.

Dempsey, B.A., J. DeWolfe, D. Hamilton, Y. Lee, R. Liebowitz, and H.A. Elliott. 1989. Land application of water plant sludges. p. 537-543. In Proc. 44th Purdue Industrial Waste Conf., Purdue Univ., West Lafayette, IN. 9-11 May 1989. Lewis Publ., Chelsea, MI.

Elliott, H.A., G.A. O’Connor and S. Brinton, 2002. Phosphorus leaching from biosolids-amended sandy soils. J. Environ. Qual. 31: 681-689.

Elliott, H.A., and B.A. Dempsey. 1991. Agronomic effects of land application of water treatment sludges. J. Am. Water Works Assoc. 83:126-131.

Elliott, H.A., and L.M. Singer. 1988. Effect of water treatment sludge on growth and elemental


composition of tomato shoots. Commun. Soil Sci. Plant Anal. 19:345-354.

Elliott, H.A., B.A. Dempsey, D.W. Hamilton, and J.R. DeWolfe. 1990. Land application of water treatment sludges: Impact and management. Am. Water Works Assoc. Res. Foundation, Denver.

El-Swaify, S.A., and W.W. Emerson. 1975. Changes in the physical properties of soil clays due to precipitated aluminum and iron hydroxides: I. Swelling and aggregate stability after drying. Soil Sci. Soc. Am. Proc. 39:1056-1063.

Hanlon, E.A., J.S. Gonzalez, and J.M. Bartos. 1997. Mehlich 1 extractable P. Ca, Mg, Mn, Cu, and Zn. p 18-20. Chemical Procedures and Training Manual. Univ. Florida, IFAS Extension Soil Testing Laboratory (ESTIL) and Analytical research Laboratory (ARL), Gainesville.

Hanlon, E.A., G. Kidder, and B.L. McNeal. 1990. Soil, container media, and water testing: Interpretations and IFAS standardized fertilization recommendations. Circ. 817. Florida Coop. Ext. Serv., Gainesville.

Heil, D.M., and K.A. Barbarick. 1989. Water treatment sludge influence on the growth of sorghum-sudangrass. J. Environ. Qual. 18:292-298.

Ippolito, J.A., K.A. Barbarick, and E.F. Redente. 1999. Co-application effects of water treatment residuals and biosolids on two range grasses. J. Environ. Qual. 28:1644-1650.

Kidder, G., C.G. Chamblis, and R. Mylavarapu. 2002. UF/IFAS standard fertilization recommendations for agronomic crops. SL129. Soil and Water Sci., Coop. Ext. Serv., IFAS, Gainesville, FL.

Lin, S. 1988. Effects of alum sludge application on corn and soybeans. p. 299-309. In Environ. Eng.: Proc. of the Joint CSCE-ASCE Natl. Conf., Vancouver, BC, Canada. 13-15 July 1988. Can. Soc. Civil Eng., Montreal, in conjunction with Environ. Canada and the Univ. of British Columbia.

Maguire, R.O., J.T. Sims, and F.J. Coale. 2000. Phosphorus solubility in biosolids-amended farm soils in the Mid-Atlantic region of the USA. J. Environ. Qual. 29:1225–1233.

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Molina, E., I. Bornemisza, F. Sancho, and D.L. Kass. 1991. Soil aluminium and Iron fractions and their relationships with P immobilization and other soil properties in andisols of Costa Rica and Panama. Commun. Soil Sci. Plant Anal. 22: 1459-1476.

Murphy, J., and J.P. Riley. 1962. A modified single solution method for the determination of phosphate in natural water. Anal. Chim. Acta 27:31-36.

Nair, V.D., K.M. Portier, D.A. Graetz, and Walker. 2004. An Environmental threshold for degree of phosphorus saturation in sandy soils. J. Environ. Qual. 33: 107-113.

O’Connor, G.A., and H.A. Elliott. 2001. Co-application of biosolids and water treatment residuals. Final report. FL Dept. Environ. Protection. (No. S 3700 206296).

O’Connor, G.A., D. Sarkar, S.R. Brinton, H.A. Elliott, and F.G. Martin. 2004. Phytoavailability of biosolids-phosphorus. J. Environ. Qual. 33: 703-712.

O’Connor, G.A., H.A. Elliott, and P. Lu. 2002. Characterizing water treatment residuals phosphorus retention. Soil Crop Sci. Soc. Florida Proc. 61:67-73.

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Peters, J.M., and N.T. Basta. 1996. Reduction of excessive bioavailable phosphorus in soils by using municipal and industrial wastes. J. Environ. Qual. 25 (6): 1236-1241.

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NEMATOLOGY – PLANT PATHOLOGY Effect of Fungicide Application Timing on Defoliation of ‘Valencia’ Orange by

Greasy Spot in Southwest Florida

R. J. McGovern*, A. A. Stoddard III, and B. M. Cauley

ABSTRACT

Large-scale expansion of citrus production occurred in the early 1990s in southwest Florida following extensive losses due to freezes in northern areas of the state. Greasy spot, caused by the fungus Mycosphaerella citri Whiteside, is a major foliar disease in warm humid climates and results in yield losses through tree defoliation and marring of fruit bound for the fresh market. Previous research conducted in central Florida indicated that effective control of greasy spot could be achieved in a number of cases with a single application of fungicide in June or July. In an experiment repeated during three seasons from 1993 to 1996, we examined alternative fungicide schedules for management of defoliation caused by M. citri in ‘Valencia’ orange [Citrus sinensis (L.) Osbeck] on ‘Swingle’ citrumelo rootstock [C. paradisi Macf. x Poncirus trifoliata (L.) Raf.] planted in a commercial grove in Immokalee, FL. The experiments utilized a RCB design with four replicates (10-tree plots) per treatment. Copper hydroxide (2.2 kg ha-1) plus spray oil (FC 435-66, 47.3 L ha-1) were applied in mid May, June, July or August using an air blast sprayer at >470 L ha-1. Trees were rated visually for percentage of defoliation in late January (1994) or February (1995, 1996) using the Horsfall-Barratt rating scale. The results confirmed that application of fungicides in mid June or July provided the most consistently effective control of greasy spot defoliation in southwest Florida. Decreases in defoliation resulting from June or July treatment ranged from 15-44% compared with the non-treated control.

INTRODUCTION

Greasy spot was first reported in Florida in 1915 (Fawcett, 1915) and remains one of the most economically significant foliar diseases of citrus in the state. Leaves of all commercially grown Citrus spp. and many related genera are susceptible to some extent (Whiteside, 1972).

Disease symptoms progress from yellow spots on the adaxial leaf surface to irregular greasy lesions on both sides of leaves and premature defoliation. Free water or near 100% relative humidities and high temperatures (≥25o

C) are essential for M. citri ascospore germination (Whiteside, 1976). Initial infection of citrus leaves by ascospores of M. citri was shown to occur most commonly in July and August in central Florida after the onset of the rainy season and warm weather (Whiteside, 1976).

Subsequent studies demonstrated that adoption of under-tree irrigation systems for citrus production may result in increased ascospore release and a more prolonged infection period encompassing most of the year (Timmer et al., 1995; Timmer et al., 2000). Greasy spot has a long incubation period, usually exceeding 4 months on orange and grapefruit (Citrus x paradisi Macf.) (Whiteside, 1976). Defoliation from infection by M. citri in central and south Florida may occur before full leaf symptoms develop but is generally not extensive until after the onset of cold weather in December.

In Florida, losses of up to 25 and 45% of fruit yield of sweet orange and grapefruit, respectively, have been caused by defoliation induced by M. citri (Timmer and Graham, 2000). Severe defoliation may also make infected trees less able to recover from cold damage (Whiteside, 1984). The pathogen can produce additional losses by marring fruit, especially grapefruit, bound for the fresh market. It was determined that in a number of cases a single application of a copper fungicide alone or in combination with an oil emulsion in June or July resulted in effective control of greasy spot in central Florida (Whiteside, 1984).

As a result of severe freezes in Florida during the mid and late 1980s, citrus production was rapidly and extensively expanded in the state’s southwest area. Original pathogen characterization and research on the management of greasy spot were conducted in central Florida. Because of climatological and edaphic differences between central and southwest Florida our research objective was to test alternative spray schedules for management of greasy spot in the latter region.


Experimental Site and Design

An experiment was repeated during three growing seasons in a 3-yr-old grove of ‘Valencia’ orange on ‘Swingle’ rootstock in Immokalee, FL, in the southwestern region of the state (26.25o N, 81.25o W) between 1993 and 1996. A RCB design with four replicates (10 tree-plots) was used. The trees were planted in double rows on swales running north and south. Five trees on each side of the swale were utilized for fungicide and control replicates, and each was separated by a two-tree buffer. Each

R.J. McGovern, Dep. Plant Pathology and Plant Medicine Program, Univ. of Florida, Gainesvillle, FL 32611-0680; A.A. Stoddard III, LAN Associates, Inc., St. Augustine, FL 32084; B. M. Cauley, Barron Collier Co., Silverstrand Groves, Immokalee, FL 34142

*Corresponding author ([email protected] ). Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:49-51 (2006).



experiment was conducted in the same production block but utilized different trees on adjacent swales.

Treatments consisted of copper hydroxide (Kocide 101, 2.2 kg ha-1; Griffin LLC, Valdosta, GA) and oil (Sunspray 7E, 47.3 L ha-1; Sunoco, Inc. Philadelphia, PA) combination applied once in mid April, May, June, July, or August of each year (1993-1995) at >470 L ha-1 using a commercial airblast sprayer and a non-treated control.

Disease Evaluation

The east and west side of each tree was rated for defoliation in late January (1994) or February (1995, 1996) using the 0 to12 Horsfall-Barratt rating scale converted to percentage (Horsfall and Barratt, 1945). The two disease ratings for each tree were averaged before data analysis.

Data Analysis

Data was subjected to analysis of variance (ANOVA) using SAS and means were separated using Fisher’s Protected LSD Test following ANOVA (SAS, 2004). Because of the variation in environmental conditions occurring during the three growing seasons, data from each year were analyzed separately. Depending on the nature of the data, either square root or arc sine square root transformations were used on data prior to statistical analysis (Gomez and Gomez, 1984). Non-transformed arithmetic means are reported.


Average rainfall in Immokalee during May in 1993, 1994, and 1995 was below (≥10% reduction) the 30-year average (1960-1990) recorded at the University of Florida Southwest Florida Research and Education Center (Fig. 1) (Reeder, 1993; Tavares, 1994, 1995). Rainfall during June, July and August was below and above the 30-year average in 1993 and 1995, respectively, and close to the average in 1994. Mean monthly air temperatures were close to the 30-year average (varied by <10%) and conducive to infection by M. citri during May through August in 1993, 1994, and 1995 (Fig. 2). Average monthly minimum relative humidity was very similar during 1993, 1994, and 1995 (Fig. 3).

Defoliation in non-treated control trees was moderate and ranged from 25 to 31% over the three years (Table 1). Even with this moderate rate of disease pressure, applications of copper hydroxide and oil generally improved leaf retention (minimum leaf loss in treated trees was 14.6%). The variation in response to timing of fungicide application across the years was probably due to differences in rainfall patterns (Fig. 1) which delayed or accelerated infection by M. citri Consistently only the mid June or mid July improved leaf retention (P < 0.05) compared to the non-treated control all three years.

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Figure 1. Average monthly rainfall (cm) recorded at University of Florida Southwest Florida Research and Education Center, Immokalee, FL in May-August, 1993-1995. (+) and (-) indicate that the rainfall varied by ≥10% from the 30-year average recorded at UF-SWFREC.

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Additionally, there was no difference between the June or July application times, regardless of year.

Our findings are similar to and confirm previous research on timing of fungicides for greasy spot management conducted in central Florida (Whiteside, 1976). Subsequent work conducted in 1997 and 1998 in both central and southwest Florida (Timmer et al., 2000)

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Table 1. Effect of fungicide application schedule on defoliation from M. citri in ‘Valencia’ orange in southwest Florida, 1993-1996. Defoliation†Fungicide application schedule

1993-1994 1994-1995 1995-1996 -------------------------------------- % ------------------------------------- Nontreated control 25.1 a*‡ 31.4 a** 27.8 a** Mid May 28.8 a 29.6 a 24.4 abc Mid June 21.0 b 26.6 b 20.2 c Mid July 14.6 b 27.0 b 22.1 bc Mid August 21.1 ab 30.5 a 26.2 ab †Defoliation was estimated (10 tree-plots) in late January in 1995 and late February in 1994 and 1996 using the Horsfall-Barratt rating scale. ‡Different letters following means within columns indicate significant differences by Fisher’s Protected LSD Test; *, ** indicate differences at P≤0.05 and P≤0.1, respectively. Square root or arc sine square root transformation was performed on data before analysis; non-transformed data are presented.

confirm these findings. Current University of Florida recommendations for greasy spot control in southwest Florida are a fungicide spray in June followed by a second application in August to protect any summer growth flush that emerged after the first treatment (Timmer et al, 2001). In addition to proper timing, correct fungicide rates and good spray coverage of the lower leaf surface are essential for effective greasy spot management.

REFERENCES

Fawcett, H. S. 1915. Citrus diseases of Florida and Cuba compared with those of California. California Agr. Exp. Sta. Bull. 262.

Gomez, K. A., and A. A. Gomez. 1984. Statistical procedures for agricultural research. 2nd Ed. John Wiley & Sons, New York.

Horsfall, J. G. and R. W. Barratt. 1945. An improved grading system for measuring plant disease. Phytopath. 35:655.

Reeder, R. K. 1994. Climatological Data – 1993. Univ. of Florida, Institute of Food and Agric. Sci., Southwest Florida Res. and Educ. Ctr,, Immokalee.

SAS, Institute. 2004. SAS Version 10.0 for Windows. SAS Institute, Inc., Cary, NC.

Tavares, M. 1995. Climatological Data – 1994. Univ. of Florida, Institute of Food and Agric. Sci., Southwest Florida Res. and Educ. Ctr,, Immokalee.

Tavares, M. 1996. Climatological Data – 1995. Univ. of Florida, Institute of Food and Agric. Sci., Southwest Florida Res. and Educ. Ctr,, Immokalee.

Timmer, L. W., T. R. Gottwald, R. J. McGovern, and S. E. Zitko. 1995. Time of ascospore and infection by Mycosphaerella citri in central and southwest Florida. Proc. Fla. State Hort. Soc. 108: 374-377.

Timmer, L. W., and J. H. Graham. 2000. Greasy spot and similar diseases. p. 25-29. In L. W. Timmer, S. M. Garnsey, and J. H. Graham (ed). .Compendium of Citrus Diseases. 2nd Edition. APS Press, St. Paul.

Timmer, L.W., P. D. Roberts, H. M. Darhower, P. M. Bushong, E. W. Stover, T. L. Peever, and A. M. Ibanez. 2000. Epidemiology and control of citrus greasy spot in different citrus-growing areas in Florida. Plant Dis. 84:1294-1298.

Timmer, L.W., P.D. Roberts, K. R. Chung, and A. Bhatia. 2001. Greasy Spot. Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Fact Sheet PP-154.

Whiteside, J. O. 1972. Histopathology of citrus greasy spot and identification of the causal fungus. Phytopath. 62:260-263.

Whiteside, J. O. 1976. Epidemiology and control of greasy spot, melanose, and scab in Florida citrus groves. PANS 22:243-249.

Whiteside, J. O. 1984. Spray programs. Citrus Indust. 65:23-27.


Effects of Solarization and Ammonium Amendments on Disease and Yield in Snap Bean and Summer Squash

R. J. McGovern*, R. McSorley, T. E. Seijo, T. A. Davis, and K.-H. Wang

ABSTRACT

Two experiments were conducted during Spring in west central Florida to evaluate the effectiveness of soil solarization alone and in combination with two soil amendments, Armicarb 300 (ammonium bicarbonate plus surfactant, 336 kg ha-1) or ammonium sulfate (281 kg ha-1) in managing soilborne pathogens and increasing biomass in snap bean (Phaseolus vulgaris L.) and summer squash (Cucurbita pepo L.). Two fields naturally infested with Fusarium sp., Pythium sp. and Rhizoctonia solani in Bradenton, FL, were used. Plots (9.0 m2) were solarized for 3 weeks in April using two layers of 25-μm clear low-density polyethylene mulch, separated by a 0.5-m air space. Following solarization, snap beans and summer squash were seeded into the plots. In general, solarization significantly (P < 0.05) decreased the progress of crown and root disease and final disease incidence in snap bean (Phaseolus vulgaris L.), increased survival in summer squash (Cucurbita pepo L.), and increased yield and/or shoot fresh weight in both crops. Both soil amendments increased (P < 0.05) the survival of squash plants in both experiments and the yield (fruit weight) of snap beans and shoot fresh weight of squash in single experiments. Neither amendment enhanced the effect of solarization in suppressing soilborne pathogens.

INTRODUCTION

Increasing attention has been focused on solarization as a soil disinfestation procedure because of its relatively benign environmental impact in comparison with other techniques including fumigation (Katan and Devay, 1991; McGovern and McSorley, 1997). Typically solarization has been conducted for one month or longer during the summer in areas with little attendant cloud cover or precipitation (Katan, 1980). Results with solarization have been variable in subtropical and tropical locations with frequent rainfall including peninsular Florida (McGovern and McSorley, 1997). We demonstrated that solarization conducted in autumn for 3 to 6 weeks using a single clear layer of low density polyethylene mulch reduced Phytophthora blight [Phytophthora nicotianae Breda de Haan var. parasitica (Dastur) G. M. Waterhouse] in central and south Florida (McGovern and McSorley, 2000). We also showed that use of a double layer of clear mulch was effective in increasing biomass and reducing soilborne pathogens of impatiens (Impatiens x wallerana) including Fusarium sp., Pythium sp. and Rhizoctonia solani Kühn (McGovern et al, 2002). A number of studies have

investigated the combined effects of solarization and ammonia-based soil amendments such as ammonium phosphate, ammonium bicarbonate, ammonium sulfate, or manures against a range of soilborne plant pests with variable results (Gamliel and Stapleton, 1993; Gaur and Dhingra, 1991; Lodha, S., 1995; McSorley and McGovern, 2000). Our research objectives were to investigate the individual and combined effectiveness of solarization in spring along with ammonium amendments for managing soilborne disease in vegetable crops.


Experimental Sites

Two fields (Field 1 and Field 2) at the Gulf Coast Research and Education Center (GCREC) in Bradenton, FL, consisting of Eaugallie fine sand (970 g kg-1 sand, 10 g kg-1 clay, 20 g kg -1 silt; pH = 5.7-6.8, organic matter = 15-20 g kg-1) and separated by 0.8 km were used for experimentation. The sites had been used to produce primarily solanaceous and cucurbit crops during the previous 30 years and were naturally infested with soilborne pathogens including Fusarium spp., Pythium spp., and Rhizoctonia solani. In addition, Field 2 had an extremely high nutsedge (Cyperus rotundus L and C. esculentus L.) density (120 plants 0.09-2).

Experimental Treatments

The experiment utilized 3.0-m x 3.0-m plots arranged in a randomized complete block design with four replications per treatment. The experimental design was a 2 (solarization vs. no solarization) x 3 (no amendment vs. Armicarb 300 vs. ammonium sulfate) factorial experiment, conducted twice in Field 1 and Field 2, respectively. The soil was thoroughly tilled and wetted prior to solarization. Soil solarization was accomplished using a double layer of 25 μm thick, clear, low density polyethylene mulch (DowAgrosciences, Indianapolis, IN). The second layer was raised 0.5 m above the first by means of two arches created with 2.5 cm-diameter PVC pipe anchored in each corner of the plots. In addition, a single plot mulched with one layer was established solely for the purpose of soil temperature measurement during solarization.

R. J. McGovern, Dep. Plant Pathology and Plant Medicine Program, Univ. of Florida, Gainesvillle, FL 32611-0680, R. McSorley and K.-H. Wang, , Dep. Entomology and Nematology, Univ. of Florida, Gainesville, FL 32611-0620, and T. E. Seijo and T. A. Davis, University of Florida-IFAS, Gulf Coast Research and Education Center, Bradenton, FL 34203.

*Corresponding author: R. J. McGovern, ( [email protected] ). Contribution published in Soil Crop Sci. Soc. Florida Proc. 65:52-57 (2006).

Soil amendments consisted of Armicarb 300 (Church & Dwight Co., Inc., Princeton, NJ 08543-5297) a proprietary formulation of ammonium bicarbonate plus a surfactant, 336 kg ha-1) or ammonium sulfate (281 kg ha-1). Amendments were incorporated into the soil to a depth of 15-20 cm through cultivation with a rototiller (rotovation).



Control (non-amended) plots were rotovated in the same manner.

Soil temperatures were measured in bare soil, in soil mulched with a single layer of mulch, and in soil covered with the double raised layer of mulch. Temperatures were measured at three depths (5, 15, and 23 cm) in each of these soils by means of data loggers (WatchDog 400 Data Logger, Spectrum Technologies, Plainfield, IL). Solarization was begun on 9 April, 1999 in Field 1 and on 7 April in Field 2, and terminated in both fields after 3 weeks by removal of mulch.

In Field 2, the control plots and those treated only with Armicarb 300 or ammonium sulfate were rotovated because of extensive (≥90%) nutsedge coverage. Weeds were removed as needed from other plots in both fields by hand. Reoccurring weeds were removed by hand as needed throughout the experiment; emergence of nutsedge plants was especially problematic in the solarized plots in Field 2.

Following weed removal, each plot was split into half. Half of the plot was planted with 16 ‘Storm’ snap bean, and the other half with 6 ‘Goldie’ yellow summer squash. Plants were watered by a semi-closed seep irrigation system consisting of shallow ditches located at each side of the field. No fertilizers other than the experimental amendments were applied. Pesticide usage for insect control on plants was limited to applications of Bacillus thuringiensis formulations for control of lepidopteran larvae.

Soil Analysis

Six cores were taken from each plot to a depth of 15 cm for soil analysis. These analyses included soil electroconductivity and pH, and soil concentration of NH4-N and NO3 -N and were performed using standard soil testing procedures [University of Florida-IFAS, Analytical Research Laboratory, Gainesville, FL 32611 (http://arl.ifas.ufl.edu/ARL%20pages/ARLAnalysis.htm)].

Disease Evaluation

Disease (wilting and death) incidence was monitored weekly for 7 weeks in snap bean and was summarized by calculating the area under the disease progress curve (AUDPC) (Shanner and Finney, 1977). Over the course of the experiment, discolored tissue segments from the roots and crown of diseased snap bean plants were surface disinfested in 0.5% NaOCl , placed on selective media, and incubated at 28o C to detect Fusarium spp., Pythium spp., and/or R. solani (Jeffers and Martin, 1986; Sumner and Bell, 1982). A total of nine and ten bean plants were sampled in Fields 1 and 2, respectively.

Squash plant survival (percentage of surviving plants) was recorded at the termination of the experiment. One 2-3 cm section of a discolored root from each treatment replication of squash (six treatments x four replications =

24 root pieces) were assayed for Fusarium sp., Pythium sp., and/or R. solani as described above. Culture plates were checked daily for microbial growth, and fungal colonies were identified morphologically by means of microscopic examination.

Plant Biomass Assessment

Beans were harvested on 18 and 25 June in Field 1, and on 21 and 25 June, and 2 July in Field 2. Squash were harvested on 8 and 15 June. After the final harvest, the fresh weight of squash plants shoots (stems and leaves) were obtained for each treatment replication.

Data Analysis

Data was subjected to a 2×3 factorial analysis of variance using SAS (Anon., 2004). When significant (P < 0.05) amendment effects or interactions occurred, amendment means were separated using Fisher’s Protected LSD Test following. Arc-sine square root transformations were used where appropriate on percentage data prior to statistical analysis (Gomez and Gomez, 1984), but untransformed arithmetic means are reported.


The average ambient temperature during solarization was slightly below (-5.0%) the 40 year cumulative average recorded at GCREC, and rainfall was 71.9% below normal (Anon., 2000; Stanley, 1999). May was slightly cooler (-13.1%) but much drier (-87.2%) than usual. The average temperature during June was very close (-1.0%) to normal while rainfall was slightly higher (+15.7%). Mean maximum soil temperatures were highest at all depths under double mulch (Table 1). Soil temperatures recorded under single mulch were intermediate between double mulch and bare soil.

Table 1. Effect of single and double clear low density polyethylene mulch on mean maximum soil temperature April 9-30, 1999 in a field in Bradenton, Florida.

Mean maximum soil temperature (oC) † Treatment 5 cm 15 cm 23 cm Bare soil 31.5 30.1 28.5 Single LDPE 42.0 34.2 30.5 Double raised LDPE‡ 46.9 36.2 33.7 † Temperatures were recorded using a Watch Dog 400 DataLogger. ‡LDPE = low density polyethylene. The second layer was raised 0.5 m above the first.

Other researchers have demonstrated that using double layers of clear plastic mulch to create an intervening air space achieved higher soil temperatures during the summer than a single layer (Ben Yephet et al, 1987; Duff and Connelly, 1993). The soil temperatures measured during solarization conducted in spring in this experiment were comparable with temperatures recorded at the same site and depths using double clear mulch in the fall (September-October) or single clear mulch in the summer

http://arl.ifas.ufl.edu/ARL%20pages/ARLAnalysis.htm


Table 2. Effect of solarization and ammonium amendment on soil electroconductivity, pH, and nitrogen at planting†

Electroconductivity (mS cm-1) pH NH4-Nitrogen (ppm) NO3-Nitrogen (ppm) Field and Treatment Control Solarized Amend.

means Control Solarized Amend. means Control Solarized Amend.

means Control Solarized Amend. means

Field 1Control 1.4 1.4 1.4 5.8 6.0 5.9 1.2 2.0 1.6 b*‡ 2.4 3.7 3.0 b** Ammonium sulfate 1.8 1.5 1.6 5.7 5.9 5.8 1.8 4.3 3.0 a 7.0 4.0 5.4 a

Armicarb 300 1.8 1.5 1.7 5.7 6.0 5.8 1.5 3.7 2.6 a 7.8 4.9 6.4 a Solarization means 1.7 1.5 5.8 B** 5.9 A 1.5 B* 3.3 A 5.7 4.2

Field 2Control 1.6 1.4 1.5 6.8 6.5 6.6 0.8 1.0 0.9 0.4 3.4 1.9 b** Ammonium sulfate 1.5 1.8 1.7 6.7 6.6 6.6 1.0 5.0 3.0 2.5 7.4 5.0 a

Armicarb 300 1.6 1.5 1.5 6.8 6.6 6.7 1.0 1.7 1.4 2.8 7.4 5.1a Solarization means 1.6 1.6 6.8 6.6 0.9 2.5 1.9 B* 6.0 A †Data based on six pooled 300-cm3 soil samples from each of four 9.0-m2 plots. ‡Different letters following means within columns (a, b, c) and rows (A, B) indicate significant differences by Fisher’s Protected LSD Test; *, ** indicate differences at P ≤0.01 and P ≤0.05, respectively. The absence of letters following means within columns indicates that significant main plot x subplot interactions did not occur or that means did not differ significantly. Arc sine square root transformation was performed on percentage data before analysis; non-transformed data are presented.

Table 3. Recovery of Fusarium, Pythium, and Rhizoctonia sp. in discolored roots and crowns of snap bean ‘Storm’, and summer squash ‘Goldie’. Fusarium Recovery (%) Pythium Recovery (%) Rhizoctonia (%) Crop

Field 1 Field 2 Field 1 Field 2 Field 1 Field 2 Bean† 44.0 60.0 0.0 80.0 44.4 30.0 Squash‡ 72.9 14.6 29.2 41.6 8.3 16.6 †Discolored roots and crown segments from nine and ten snap beans plants in Fields 1 and 2, respectively, were assayed using selective media for the three pathogens. ‡ Discolored root segments of summer squash plants from each treatment replication in Fields 1 and 2, respectively, were assayed using selective media for the three pathogens.

(July-August) (McGovern and McSorley, 2000; McGovern et al, 2002; Overman and Jones, 1986).

Application of ammonium bicarbonate or ammonium sulfate did not significantly affect either soil electroconductivity or pH (Table 2). Solarization decreased soil pH in Field 1. Soil pH was higher in Field 2 (average pH = 6.8) than Field 1 (average pH = 5.8) (Table 2). In Field 1, plots treated with solarization, Armicarb 300 or ammonium sulfate had significantly (P < 0.05) higher soil concentrations of ammonium nitrogen than the non-treated control or other treatments. A similar non-significant trend was observed with respect to ammonium nitrogen in Field 2. This inter-field variation may have been caused by extraction of ammonium nitrogen by the extremely high densities of nutsedge present in Field 2. Purple nutsedge is capable of mobilizing and storing up to 815 kg ammonium sulfate per hectare (Holms et al, 1977). The highest soil concentrations of nitrate nitrogen were detected in those plots treated only with Armicarb 300 or ammonium sulfate in Field 1, and in the solarization plus either Armicarb 300 or ammonium sulfate in Field 2.

Fusarium spp. and Rhizoctonia solani were recovered at moderate to high incidences from the roots and crowns of declining bean plants in both fields, while the recovery of Pythium spp. only occurred in symptomatic bean plants from Field 2 (Table 3). Fusarium spp., Pythium spp., and R. solani were detected at various incidences from discolored squash root pieces from both fields. Multiple

infections by two or more of the three detected pathogens were common in both symptomatic plants and discolored root pieces (data not shown). We, therefore, hypothesize that a complex of Fusarium spp., Pythium spp. and R. solani, possibly along with other potential soilborne pathogens, incited the root and crown diseases observed in the snap bean and summer squash in these experiments.

Very high final incidences of root and crown rot and mortality were observed in bean plants in both fields (Table 4). Soil solarization significantly (P < 0.05) reduced both final disease incidence and the AUDPC when compared to the non-treated control in Field 1. However the disease reduction by solarization was not significant in Field 2. It is interesting to note that the disease suppressive effect of solarization followed the trend in the concentration of NH4-N in the soil (Table 2). The high levels of nutsedge may have compromised the effectiveness of solarization in Field 2 by providing a thermally protective reservoir for plant pathogens, by weakening plants through resource competition, and because of the contamination of treated soil that accompanied hand removal of the weeds. The two soil amendments had no significant effect on disease progress or final disease incidence in bean in either field and did not appear to enhance the pathogen suppressiveness of solarization.

The yield of snap beans was significantly increased compared to the non-treated control in Field 1 by solarization and by each of the soil amendments and was


Table 4. Effect of soil solarization and amendment on disease progress and final incidence and yield in snap bean ‘Storm’ Final disease incidence † AUDPC (%)‡ Yield/plot (kg) §

Field and treatment¶ Control Solarized Amend.

means Control Solarized Amend. means Control Solarized Amend.

means Field 1Control 89.0 81.2 85.2 2706 1719 2213 1.2 0.9 1.0 b** Ammonium sulfate 96.8 79.7 88.3 2761 1186 1974 3.2 12.9 8.0 a

Armicarb 300 84.4 68.8 76.5 1634 833 1234 5.5 15.0 10.3 a Solarization means 90.1 A**# 76.6 B 2367 A* 1246 B 3.3 B** 9.6 A

Field 2Control 79.7 86.0 82.8 2117 2017 2067 2.5 1.1 1.8 Ammonium sulfate 93.4 96.9 96.1 2254 1899 2076 1.4 0.6 1.0

Armicarb 300 78.2 92.2 85.2 1693 1313 1503 12.2 0.8 6.4 Solarization means 91.7 84.4 2022 1743 5.4 0.8 †Final disease incidence (wilting and death) was determined 7 weeks after planting. ‡AUDPC = area under the disease progress curve. Disease symptoms (wilting and death) were monitored weekly for 7 weeks after planting16 snap bean seeds/plot. §Yield data based on two and three harvests in Fields 1 and 2, respectively. ¶Armicarb 300, a proprietary formulation of ammonium bicarbonate plus surfactant, was applied at 336 kg/ha. Ammonium sulfate was applied at 281 kg ha-1. #Different letters following means within columns (a, b, c) and rows (A, B) indicate significant differences by Fisher’s Protected LSD Test; *, ** indicate differences at P ≤0.01 and P ≤0.05, respectively. The absence of letters following means within columns indicates that significant main plot x subplot interactions did not occur or that means did not differ significantly. Arc sine square root transformation was performed on percentage data before analysis; non-transformed data is presented.

Table 5. Effect of soil solarization and amendment on final disease incidence and yield in summer squash ‘Gloria’ Plant survival (%)† Shoot fresh weight (kg) ‡ Fruit weight/plot (kg) § Field and

treatment¶ Control Solarized Amend. means Control Solarized Amend.

means Control Solarized Amend. means

Field 1 Control 55.3 88.6 66.3 c# 3.8 2.4 b** 1.4 b 0.0 2.9 1.9 Ammonium sulfate 44.0 94.3 72.0 b 5.3 99.2 a 52.6 a 1.2 16.5 11.4

Armicarb 300 77.6 94.3 94.3 a* 5.0 63.4 ab 34.2 ab 1.1 2.9 2.3 Solarization means 49.6 B* 91.5 A 4.7 B* 62.5 A 0.7 7.4

Field 2 Control 0.0 b 50.0 25.0 c* 0.0 4.1 1.5 0.0 0.1 0.06 Ammonium sulfate 91.5 a 100 95.8 a 7.6 10.2 14.1 0.0 0.2 0.1

Armicarb 300 74.5 a 58.0 66.2 b 5.0 24.6 14.2 0.5 2.8 1.7 Solarization means 55.3 B* 69.3 A 5.9 B** 15.1 A 0.2 1.1

†Final disease incidence (number of wilting and dead plants) was recorded 7 weeks after planting six summer squash seeds/plot. ‡Shoots (leaves and stems) of summer squash plants were weighed 7 weeks after seeding. §Yield data based on two harvests. ¶Armicarb 300, a proprietary formulation of ammonium bicarbonate plus surfactant, was applied at 336 kg ha-1. Ammonium sulfate was applied at 281 kg ha-1. #Different letters following means within columns (a, b, c) and rows (A, B) indicate significant differences by Fisher’s Protected LSD Test; *, ** indicate differences at P ≤0.01 and P ≤0.05, respectively. The absence of letters following means within columns indicates that significant main plot x subplot interactions did not occur or that means did not differ significantly. Arc sine square root transformation was performed on percentage data before analysis; non-transformed data is presented.

comparable with yield increases in other crops resulting from solarization conducted in the Summer (Katan and DeVay, 1991; McGovern and McSorley, 1997). The failure of solarization to increase snap bean yield in Field 2 may have resulted from an enhancement in the growth of nutsedge by sublethal temperatures generated by the solar heating. Temperatures of ≥60°C are required to rapidly kill (1 hour) purple nutsedge tubers (Smith and Fick, 1937). An oscillating temperature regime with a daily maximum of 50°C over a 2-week period was shown to be lethal to tubers of both purple and yellow nutsedge (Chase, 1999). However, daily alternating sublethal temperatures greatly stimulated sprouting (Nishimoto, 2001), which would be consistent with the temperatures observed in the

current study (Table 1).

The survival of squash plants was significantly (P < 0.05) increased by solarization and each of the two amendments in both fields (Table 5). Application of Armicarb 300 and ammonium sulfate resulted in the highest squash plant survival in Field 1 and 2, respectively. The fresh weight of squash shoots was significantly (P < 0.05) increased by solarization in both fields, but yield (fruit weight) was unaffected. Application of ammonium bicarbonate or ammonium sulfate produced significant increases in squash plants grown in solarized plots and overall, but this is not surprising since the amendments were the only N source available to the squash plants in these experiments.


Temperatures ≥50oC that are necessary to rapidly inactivate Fusarium spp., Pythium spp., and and R. solani (McGovern and McSorley, 1997) only occurred in the upper soil stratum (≤5 cm) in these experiments. Therefore, it is possible that other mechanisms in concert with thermal inactivation were responsible for the disease suppression and enhanced plant growth that we observed. Such ancillary mechanisms of disease suppression by solarization may include weakening of pathogens through sublethal heating, buildup in the soil of toxic compounds, and increases in the populations of beneficial microorganisms (DeVay and Katan, 1991; Lifschitz et al, 1983; Stapleton and DeVay, 1986; Stapleton et al, 1991). Nevertheless, even with the relatively short solarization time of 3 weeks, reduction of soilborne disease progress and improved plant performance were observed under these spring conditions.

This research did not support our hypothesis that combining ammonium amendments with solarization could enhance disease suppression as no interaction between solarization and amendment effect was observed. However, our research did demonstrate the potential of double-mulch soil solarization conducted in the Spring for reducing disease and increasing plant growth of vegetable crops in Florida and supports the expansion of the window for solarization in areas with similar humid, subtropical climates.

LITERATURE CITED

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Jeffers, S. N., and S. B. Martin. 1986. Comparison of two media selective for Phytophthora and Pythium spp. Plant Dis. 70:1038-1043.

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Katan, J. and J. E. Devay. 1991. Soil solarization:Historical perspective, principles and uses. pp. 23-27 In: J. Katan and J.E. Devay (Eds.) Soil Solarization. CRC Press, Boca Raton, FL.

Lifshitz, R., M. Tabachink, J. Katan, and I. Chet, 1983. The effect of sublethal heating on sclerotia of Sclerotium rolfsii. Can. J. Microbiol. 29:1607-1610.

Lodha, S. 1995. Soil solarization, summer irrigation and amendments for control of Fusarium oxysporum f.sp. cumini and Macrophomina phaseolina in arid soils. Crop Prot. 14:215-219.

McGovern, R.J., and R. McSorley. 1997. Physical methods of soil sterilization for disease management including soil solarization. pp. 283-313 In: N.A. Rechcigl and J.A. Rechcigl (Eds.) Environmentally Safe Approaches to Crop Disease Control. CRC Press, Boca Raton, FL.

McGovern, R. J., and R. McSorley. 2000. Reduction of Phytophthora blight of Madagascar periwinkle in southwest and west central Florida by soil solarization in autumn. Plant Dis. 84:185-191.

McGovern, R. J., R. McSorley, and M. L. Bell. 2002. Reduction of landscape pathogens in Florida by soil solarization with double-layered plastic mulch. Plant Dis. 86:1388-1395.

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GRADUATE STUDENT FORUM ABSTRACTS

Transport of Water, N-forms, and Potassium Through Plastic Mulched Beds Cropped with Vegtables Under Drip Irrigation

K. A. Mahmoud*, P. Nkedi-Kizza, J. B. Sartain, E. H. Simonne, M. D. Dukes and R. S. Mansell, Univ. of Florida

Over irrigation and fertilization of crops grown in sandy soils can lead to leaching of mobile nutrients such as nitrate-N below the root zone. A fertigation study was carried out at North Florida Research and Education Center, University of Florida, to investigate the effect of irrigation and N-fertilizer rates on plant growth, yield, and movement of water, N-forms, potassium, and bromide in the soil profile. Four vegetable crops (bell peppers, cabbage, watermelons, and pumpkins) were grown on sandy soil plastic mulched beds during two seasons. The treatments included three irrigation rates 66%, 100%, and 133 % and two N rates 100% and 125% of IFAS recommendations which were arranged in a completely randomized block design with four replicates. Br a tracer for water and nitrate-N was simultaneously applied with the fertilizers in all plots. The main objective of the study was to find the best management practice that would give optimum crop yield and yet reduce leaching of water and nutrients below the root-zone. Data showed no significant effect of irrigation rate on the crop yield. However, N application rate had a significant effect. Br was detected below the root zone within 24 hours after application regardless of irrigation rate. During the growing season, NO3-N, NH4-N and K all leached below the root zone in all treatments. Based on this study, the best management practice would be a combination of 66% irrigation rate and 100% N rate of IFAS recommendation which would maximize yield while minimizing nutrient leaching.

*K. A. Mahmoud, 352-392-1951 ext. 234, [email protected] .

Chemical Characterization and Mineralization Rates of Selected Biosolids and Organic Wastes

C.B. Reis*, J. B. Sartain, J. E. Rechcigl, C. D. Stanley and M. B. Adjei, Univ. of Florida

Biosolids can be used as nutrient sources in agricultural and horticultural areas. The objectives was to chemically characterize the materials relative to their nutritional value and potential toxic environmental impact and determine the mineralization rates of the materials relative to their ability to supply nutritional fertility. The materials used in this study were: Limed Slurry, Limed Cake, Black Kow, Black Hen, Disney Compost, Milorganite, N-Viro and Baltimore Pellets. All materials were characterized for N, P, K, Ca, Mg, Fe, Mn and heavy metals (Cd, Zn, Cu, Pb, Mo and As) using four repetitions. Milorganite contained the highest N content followed by Black hen and Baltimore pellets. Limed slurry contained more than 2% N and P; Limed Cake, Limed Slurry and N-Viro had adequate amounts of Ca while all the sources had adequate amounts of Mg. Milorganite and baltimore pellets contained the highest levels of Fe (39500 and 39000 ppm respectively) while baltimore and black hen had the largest amount of Mn (850 and 550 respectively). All the biosolids tested contained low heavy metals concentrations. For the mineralization study, the materials (90Kg/ha and 180Kg/ha), were mixed with an uncoated white sand and a surface layer of Arredondo fine sand and placed into incubation lysimeters. A CO2 trap of 1N NaOH was placed in the head space of the lysimeters to estimate microbial decomposition rate. Limed slurry had the highest percent mineralization at both rates, followed by Milorganite and Baltimore pellets. Based on CO2 evolved, microbial activity appeared to be occuring. Biosolids appear to have satisfactory nutritional values and mineralization rates.

*C. B. Reis, 352-392-1804 ext. 326, [email protected] .

Characterization of Sorption of Pesticides Applied to Carbonatic Soils of South Florida and Puerto Rico.

G. Kasozi*, P. Nkedi-Kizza, W. Harris, Y. Li, D. Hodell and D. Powell, Univ. of Florida

Sorption is a major process that determines the fate of pesticides in the environment. This study aims at understanding soil factors that determine interactions of organic pesticides in carbonatic soils. In US, there are about 500 soil series with




carbonatic mineralogy, 12 of them occur in South Florida and 8 in Puerto Rico. Eighty five percent of Florida’s vegetables and tropical fruits are grown on these soils. The soils are very shallow, moderately well drained to poorly drained, characterized by a high water table, and underlain by limestone bedrock. The sub-tropical climate in South Florida and Puerto Rico encourages proliferation of pests and consequently a variety of pesticides are used to control the pests. Several pesticides applied to crops grown on carbonatic soils have been reported in both surface and ground water of South Florida and Puerto Rico. Although a lot of research has been done on characterizing the sorption of organic pesticides in non-carbonatic soils, a literature search indicates lack of these data for carbonatic soils. Our data on Atrazine, Duiron and Carbaryl sorption indicate that these pesticides adsorb less on carbonatic soils compared to the non-carbonatic soils. The sorption coefficients are about 1/3 of those reported in the literature for non-carbonatic soils. Use of literature pesticide sorption data in transport models is likely to underestimate the potential for pesticides to pollute groundwater in South Florida and Puerto Rico.

*G. Kasozi, 352-392-1951 ext. 234, [email protected] .

Capillary Fringe Associated with Hydrologic Soil Indicators at Sandhill Lakes T.C. Richardson* and P. Nkedi-Kizza, Univ. of Florida

Consumptive use of water can result in harm to the resource including unacceptable ecological changes to aquatic ecosystems. Florida’s Water Management Districts are required to establish Minimum Flows and Levels (MFLs) in order to prevent significant harm to the structure and functions of these systems. The objective of this study was to support the development of MFLs methods for sandhill lakes, where vegetation tends to be an unreliable hydrologic indicator and where there is limited hydrologic data. Measures of capillary fringe offer the potential to develop criteria and thresholds for MFLs determinations. FH and FL soil indicators represent historic hydrology, 20% and 80% stage exceedance respectively, whereas, MFLs represent a minimum hydrologic regime. “Undisturbed” soil cores were collected adjacent to the FH and FL soil indicators and used to determine the physical soil properties, physically measure the capillary fringe via determination of the water content above a fixed water table, and soil moisture release curves (SMRC). A reduction of historic water levels equal to the capillary fringe is thought to maintain the structure and functions of a system while allowing some water for consumptive use. Initial results show a capillary fringe of 8.7 cm (measured) and 12.5 cm (SMRC) for the FH soils and 7.2 cm (measured) and 12.1 cm (SMRC) for the FL soils. All soils have greater than 96% sand content, particle densities near 2.62 g/cm3, and organic content less than 2%. Additional study is necessary to quantify these relationships and relate physical soil characteristics to capillary fringe.

*T.C. Richardson, [email protected] .

St. Augustinegrass Phosphorus Requirement Using Hydroponic Culture Min Liu*, J. B. Sartain, G. L. Miller, W. G. Harris, P. Nkedi-Kizza and R. L. Wu, Univ. of Florida

St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze] is widely used for Florida lawn grass. At present phosphorus (P) fertilization of Florida lawn grasses is based on soil tests which were basically designed for agronomic crops in a production culture. Little information exits relative to the exact P requirement of St. Augustinegrass. The objective of this study was to determine the critical P requirement of St. Augustinegrass using solution culture techniques. Established pots of ‘Floratam’ were subject to the P treatments in solution culture at a range between 0 and 775 mg m-3 P for 148 days. Measurements included tissue and root growth rates, tissue and root P levels and visual rating of turfgrass quality. Phosphorus treatments increased tissue and root P levels with each successively higher P level. The best turf quality was achieved by the highest P treatment. Turfgrass receiving 31 mg m-3 P gained the highest root growth rate among the treatments. The tissue growth rate was increased with P treatments in a quadratic manner to a maximum value. According to linear plateau regression analysis, the critical solution P concentration was 153 mg m-3 and the critical tissue P level was 1.4 g kg-1 on dry weight basis for the optimum growth. Given the critical tissue P level, it needs further research in soil to determine the minimum fertilization level of St. Augustinegrass to achieve the critical tissue P level.

*Min Liu, [email protected] .





Application of DSSAT for Simulating Nitrogen Response of Sweet Corn C. M. Cherr*, J. M. S. Scholberg, K. J. Boote and M. D. Dukes, Univ. of Florida

Although it is an important crop in Florida, an experimentally calibrated model for sweet corn does not exist in the CERES-Maize module of the Decision Support System for Agrotechnology Transfer (DSSAT). Prediction of corn ear fresh weight from the dry weight output of the CERES-Maize model is also needed. Sweet corn growing near Citra, Florida, under five different nitrogen (N) rates (0, 67, 133, 200, and 267 kg N/ha) was sampled bi-weekly in 2002 and 2003. Fresh and dry weights and N concentrations for leaves, stems, and ears were obtained, as well as plant height and leaf number. At maturity, ear numbers, USDA grades and weights were also determined. Weather data was recorded with a Watchdog datalogger. Optimal ear yield was achieved with 200 kg N/ha in 2002, but significantly higher ear yields occurred with 267 kg N/ha in 2003. Model input files were created in DSSAT using a generic short-season variety of field corn, a representative soil profile, and information from materials and methods, weather, and experimental results. Initial fit of simulated output from the CERES-Maize model with actual data was encouraging, but simulated leaf area showed significant over-response to applied N in both years. To better calibrate simulated output, we will conduct sensitivity analysis with maize ecotype and/or cultivar parameters. Model validation will be provided using data sets from sweet corn grown in the same experimental location in 2004 and a nearby location from 2003 and 2004.

*C. M. Cherr, 352-392-1823, [email protected] .



OTHER ABSTRACTS

Crops and Fertilization Practices Elevated CO2 and Temperature Effects on Sugarcane Plant and Ratoon Crops

L. H. Allen, Jr.*, J. C. V. Vu, J. C. Anderson, and J. D. Ray, USDA-ARS, Univ. of Florida

Rising atmospheric CO2 can change productivity by increasing photosynthesis and altering growth responses to predicted global warming and changes in rainfall. In 1997-1999, we studied effects of elevated CO2 and temperatures on sugarcane, a C4 species, in paired temperature-gradient greenhouses at 360 or 700 ppm CO2 and four temperatures of baseline, +1.5, +3.0, and +4.5°C. These 1.5°C steps were maintained by a combination of computer-controlled ventilation fans and heaters. Other treatments were soil type (mineral vs. organic), water table depth (23 cm vs. 60-cm drained profile), and four cultivars (CP72-2086, CP73-1547, CP88-1508, CP80-2086). Doubled CO2 increased the following components of plant growth of a late June-early July sampling: Leaf number = 7%; Leaf area = 15%; Leaf fresh weight = 13%; Leaf dry weight = 8%; Mainstem length = 32%; Mainstem fresh weight = 31%; Mainstem dry weight = 23%; Juice volume = 40%; Total fresh weight = 25%; Juice dry weight = 36%; Total dry weight = 21%. Increasing temperatures caused a slight downward trend in sugarcane yield regardless of CO2 treatment. Cultivar yields were: CP 73-1547 > CP 80-1827 > CP 88-1508 > CP 72-2086. The number of tillers was higher in doubled CO2 Doubling CO2 may benefit sugarcane productivity more than the anticipated 10% increase for a C4 species. Physiological and productivity responses of subsequent ratoon crops to treatments will be compared with the plant crop. The increase in dry weight and juice volume of sugarcane indicate greater yield potentials as global atmospheric CO2 continues to rise.

*L. H. Allen, Jr., 352- 392-8194, [email protected] .

Thermal Units Prediction for Chilling Accumulation and Crop Development in Alabama, Florida and Georgia

J. Bellow* and C. Fraisse, Florida State Univ.

The Southeast Climate Consortium (SECC) is dedicated to applying advances in climate forecasting to agricultural and natural resources management on the consortium’s website (http://www.agclimate.org). While ENSO signals on seasonal temperature and precipitation levels are well documented for the region, little work has been done on integrated variables such as chill units (CU) or variously chilling hours and growing degree days (GDD). The accumulation of CU and GDD are particularly interesting during the Oct. to Apr. period, when ENSO teleconnections strongly influence weather patterns in the Southeastern U.S. Analysis of historic chill and growing degree days accumulation patterns as a function of ENSO phase indicates chill accumulation for blueberries (Vaccinium spp.), strawberries (Fragaria spp.), and peaches (Prunus spp.) as well as GDD for winter forages is strongly influenced by ENSO phase. El Niño events increased CU and reduced GDD for wheat in the winter months. La Niña had the inverse effect compared to neutral seasons. Differences due to the use of daily maximum and minimum temperatures compared with a model of hourly temperature were minor. Predictable differences based on the use of chill units or chill hours indicate possible overestimation of chill using chill hours. There is potential for forecasting chill accumulation and crop development rates based on GDD using ENSO climatology. The presence of significant ENSO effects at the county scale is demonstrated and a potential application for producers described.

*J. Bellow, 850-645-1253, [email protected] .

Integration and Verification of Water Quality and Crop Growth Models for BMP Planning

K. J. Boote*, J. W. Jones, and B. M. Jacobson, Univ. of Florida

This research project funded by the Florida Department of Agriculture and Consumer Services (FDACS) has the goal of improving water quality assessment and BMP implementation through the use of integrated modeling and decision support


http://www.agclimate.org/



tools. This project consolidates existing IFAS scientific program components on modeling and water quality assessment, with efforts by a private engineering firm (Soil and Water Engineering Technology, SWET) that is implementing water quality tools for use by FDACS. It integrates DSSAT crop growth models into the Watershed Assessment Model (WAM) model developed by SWET to improve capabilities for assessing alternative BMPs relative to their projected effects on yield and water quality. The project involves IFAS scientists who will document, test and improve models of important Florida crops for ability to predict growth, yield, N uptake, and N leaching under different N fertilization and irrigation schedules. Scientists will develop recommendations for minimum data to be collected in BMP experiments and improve soil-water modules to better handle flatwood soil conditions and plastic mulch bed systems typical for Florida vegetable crops. The integrated tool will be used by FDACS and consultants as a complement to intensive monitoring methods to verify compliance to BMP plans and assist farmers in BMP planning relative to N and P fertilization and management of important commodities in Florida.

*K. J. Boote, 352-392-1811 ext. 231, [email protected] .

Forage Yield and Nutritive Value of Urochloa Varieties in Southwest Florida R. M. Muchovej, P. R. Newman, and I. V. Ezenwa*, Univ. of Florida

Urochloa (syn. Brachiaria spp.) decumbens and U. humidicola are adapted to central and south Florida and compare favorably to bahiagrass (Paspalum notatum ), the predominant pasture grass in Florida. Little is known about other species or varieties that are commonly grown in the tropics. Our study determined dry matter (DM) production and nutritive value of six Urochloa varieties in southwest Florida where incidence of frost is less than in central Florida. Urochloa brizantha cv. Marandu and MG-4, U. decumbens cv. Basilisk, U. dictyoneura, U. humidicola, and U. ruziziensis were planted in July to September 1995 on Immokalee fine sand soil (Arenic Alaquod). Plots were fertilized with 37, 45, 67 kg ha–1 of N, P, and K, respectively, in the spring of each year and harvested at 10 to15-cm height every 35 d between March and December over 4 yr. Forage DM yields varied between 6.0 and 8.6 Mg ha–1 yr–1 and exhibited trends typical of bahiagrass. Basilisk had the highest annual DM yield (8.6 Mg ha–1 yr-1), and produced the highest DM yields in March-April and November-December (0.9 Mg ha–1 yr-1, respectively). Crude protein, in vitro DM digestibility, and neutral detergent fiber of the varieties ranged between 60 to 160, 400 to 700, and 550 to 850 g kg–1 DM, respectively. U. decumbens cv. Basilisk merits further evaluation as a pasture grass in southwest Florida.

*I. V. Ezenwa, 239-658-3400, [email protected] .

Simulating Crop N Balance in Crop Growth Models Used for Best Management Practice Recommendations

J. I. Lizaso*, K. J. Boote, J. W. Jones, and W. D. Batchelor, Univ. of Florida

Agriculture is an important non-point source of water pollution. Limiting the impact of agriculture on water quality requires more effective use of fertilizers and organic manures. Crop simulation models can be a cost-effective tool to optimize the management of fertilization practices, maximizing crop uptake and minimizing soil leaching. For this purpose, models require to exhibit reasonable accuracy under a wide range of environmental conditions. The purpose of this work is to review various approaches in current models to simulate crop N dynamics. Many models including those distributed with DSSAT, assume that critical N concentration, required for optimum growth, and minimum N concentration, below which no growth occurs, change with plant age. Thus, the N status of the plant is defined using the actual N concentration in relation to critical and minimum concentrations. Crop N uptake is calculated by comparing the potential soil N supply with the crop N demand. N uptake is partitioned between shoots and roots. During seed growth, the pool of N available for remobilization is compared with the grain demand for growth, and seed N concentration is calculated. An alternative approach assumes a decline in critical shoot N concentration as plants accumulate dry weight through the growing season. Other models allocate N separately to leaves and stems, and calculate the demand for N assuming a constant concentration per leaf area. When N is deficient for expansion, leaves may become thicker. We compared plant N simulations with field measurements and focused on required model improvements.

*J. I. Lizaso, 352-392-1864 ext. 298, [email protected] .





Measurement of Plant-Produced Volatile Organic Compounds in Controlled Environments

O. Monje*, I. Eraso, J. T. Richards, J. S. Sager and T. P. Griffin, Univ. of Florida, Kennedy Space Center

The accumulation of volatile organic compounds (VOCs) in spacecraft cabin air can contribute to poor air quality and impose a threat to health of the crew during longterm missions in space. The confined environment of spacecraft allows the accumulation of VOCs generated from decaying fruits in garbage bags, off-gassed from plastic materials, or produced by plants, which can affect plant metabolism if kept unchecked. Identifying the VOCs produced by plants and determining the rates at which these VOCs are produced is important for designs of VOC filters of future spaceflight plant growth chambers and for reducing risks to spacecraft systems. Production rates of plant-produced VOCs from radish crops were measured in Biomass Production System for Education (BPSe; Orbitec, Madison, WI) chambers. VOC concentrations in chamber air were analyzed with a gas chromatograph. Plant-produced VOCs were detected as soon as 8 days after planting (DAP). Radish plants produced ethylene, methanol, acetaldehyde, ethanol, dichloromethane, and acetone. VOC production rates were measured at 8, 12, and 21 DAP and expressed on a dry weight basis.

*O. Monje, 321-861-2935, [email protected] .

Germination and Vigor of Peanut Seed from Six Cultivars as Affected by Production and Storage Location

J. M. G. Thomas*, K. J. Boote, and D. W. Gorbet, Univ. of Florida

Newly developed cultivars of peanut are reported to vary in seed germination. These variations are hypothesized to result from genotype interactions with environmental differences during plant growth as well as storage conditions. The objective of this study was to test the uniformity of seed germination of six cultivars obtained from three source locations: FL Foundation Seed, UF North Florida Research and Education Center in Marianna, FL, and UF Plant Science Research and Education Unit in Citra, FL. Seed from six cultivars (C99R, Georgia Green, Hull, Gregory, Carver, and DP1) were stored at the three locations after production in 2002. In July, 2003, the seed were tested in a field germination test at the UF Campus in Gainesville, FL. Emerged seedlings were counted at 6 days and every other day until full emergence. Total weight per seedling at 21 days after sowing was obtained by harvesting 15 plants, which were bagged, dried and weighed separately to study seedling size and variability. There were highly significant differences due to source, cultivar, and the interaction of source and cultivar. Across cultivars, seed from Marianna had the highest percent germination (90%), then seed from Citra (80%), and finally, seed from FL Foundation Seed (61%). Seedlings from FL Foundation Seed were smaller at 1.23g, compared to those from Marianna or Citra (1.59 and 1.46 g, respectively). Carver seed had the highest germination (83%), while there were no differences between C99R (80%), Georgia Green (80%), Gregory (75%), and Hull (74%). DP1 had lowest germination at 71%. Seedling weight after three weeks was highest in Gregory, with no differences between C99R, Carver, Georgia Green and Hull, and the lowest seedling weight was observed in DP1.

*J. M. G. Thomas, 352-374-5891, [email protected] .

Interactive Effect of P and N Rates on Leaf Anthocyanins, Tissue Nutrient Concentrations, and Dry Matter Yield of Floralta Limpograss during

Short Day-length N. P. Shaikh*, M. B. Adjei, and J. M. Scholberg, Univ. of Florida

A field trial was conducted during the short day period of 2004-2005 at Ona, FL to study the factorial effect of nitrogen (67, 90 and 134 kg ha-1) and phosphorus (0, 11, 22, 45 and 90 kg ha-1) rates on forage dry matter yield, quality, nutrient uptake and leaf pigment concentration of limpograss (Hemarthria altissima). The N and P fertilizers were applied 45 days before harvest. There was no interaction of N and P rates on any of the measured variables. Cool season forage yield and crude protein (CP) concentration increased linearly from 137 to 350 kg ha-1, and 145 to 158 g kg-1, respectively, as P was increased from 0 to 90 kg ha-1, but yield and CP were not affected by N rate. There was a linear decreasing relationship between leaf concentration of anthocyanins and P rate of application such that forage obtained with 0 kg P ha-1 had 61% more leaf anthocyanins and purple pigmentation than with 90 kg P ha-1. There was no effect of N rate on anthocyanins content, and leaf chlorophyll concentration was similar at all levels of N and P. It was concluded that increased leaf anthocyanins was due to the cumulative stress from cool weather and lower P levels which resulted in reduced growth and yield of limpograss. In



cool weather, P played a more important role than N in controlling leaf pigmentation and forage yield.

*N. P. Shaikh, [email protected] .

Nitrogen Fertilization of Rice in Florida G. H. Snyder*, Univ. of Florida

Rice (Oryza sativa L.) nitrogen (N) fertilization was investigated in south Florida over a 2-yr period on mineral and organic soils. 15N-depleted N fertilizer was used to determine the amount of N in the rice plant derived from the applied fertilizer N. In the first year, grain yield on a sand soil was greater for 60 kg ha-1 N at mid-tiller than for fertilization at pre-flood or panicle initiation. On organic soil N had no effect on yield. On both soils, there was a clear trend for less of the N in grain to come from fertilizer N the earlier that the N was applied, indicating that the plant substituted fertilizer N for soil N when N was applied. In the second year, again N fertilization did not affect grain yield on organic soil. As in the first year, there was a general trend for less of the N in grain to come from fertilizer N the earlier that the N was applied. More fertilizer N was found in flag leaves at heading, and in straw at harvest, for N applied at panicle initiation (PI) than for earlier applications. However, by harvest time the grain and straw from N fertilized plots contained no more N than that from unfertilized plots, again indicating that the plant substituted fertilizer N for soil N when N was applied, or conversely, the plant could obtain sufficient N from the soil in the absence of N fertilization.

*G. H. Snyder, [email protected] .

Climate Change Effects Elevated Temperature Decreases Yields of Seed Grain Crops

L. H. Allen, Jr.*, K. J. Boote, P. V. V. Prasad, R. W. Gesch, A. Snyder, J. M.G. Thomas, and J. C.V. Vu,

USDA-ARS, Univ. of Florida

Temperatures are predicted to increase from rising atmospheric carbon dioxide (CO2) and other greenhouse gases. We conducted experiments in sunlit, controlled-environment chambers and temperature-gradient greenhouses to determine effects of elevated temperature and doubled CO2 not only on vegetative biomass growth factors, but especially on pollination and yield of rice, soybean, peanut, dry bean, and grain sorghum. Photosynthesis and vegetative growth of most species and cultivars were tolerant to reasonably high temperatures, but reproductive processes were not. Seed yields of rice were optimum at 25°C mean daily temperature and decreased sharply with increasing temperature to zero at 35°C (typically 10% decline for each 1°C rise in temperature), due to a decline in successful pollination. Soybean and peanut were more tolerant of high temperatures. Grain sorghum yield response to temperature was similar to rice, but dry bean was more sensitive. Pollen viability of all crops followed a temperature response similar to seed yield. Forty-three rice cultivars grown in temperature-gradient greenhouses showed a range of genetic variation in percent seed-set in response to a 5°C increase above ambient Florida temperatures. Thus, there appears to be potentials for adaptation to some increases of temperatures. Elevated CO2 did not prevent the high temperature decline in yield. Global warming will be much more detrimental to seed yields of crops than to photosynthesis and vegetative growth. However, there are potentials for crop genetic improvements to ameliorate part, but not all, of the high temperature hazards on seed yields and global food security.


Soil Carbon Sequestration Potentials of Bahiagrass and Rhizoma Perennial Peanut in Florida under Current and Global Warming Conditions

L. H. Allen, Jr.*, K. J. Boote, J. M. G. Thomas, S. L. Albrecht, and K. W. Skirvin, USDA-ARS, Univ. of Florida

Carbon sequestration in soils might offset increases of CO2 in the atmosphere. Two contrasting forage species, bahiagrass (BG), a C4 grass, and rhizoma perennial peanut (PP), a C3 legume, were grown at Gainesville, Florida, in plots in four





temperature zones (baseline-ambient, +1.5, +3.0, and +4.5 °C) in four temperature-gradient greenhouses, two each at 360 and 700 ppm CO2. The soil had been cultivated for more than 20 years before plant establishment in 1995. Soil was sampled from the top 20 cm of each plot in February 1995 and in December 2000. Soil organic carbon (SOC) increases across the six years were 1.396 and 0.746 g/kg in BG and PP, respectively, indicating that BG accumulated more SOC than PP. Mean SOC gains in BG plots at 700 and 360 ppm CO2 were 1.450 and 1.343 g/kg, respectively (no CO2 effect on BG). Mean SOC increases in PP plots at 700 and 360 ppm CO2 were 0.949 and 0.544 g/kg, respectively (elevated CO2 caused significant increases in SOC for PP). Overall, SOC increased with temperature for the first increment, and then declined with further temperature increases. The SOC increases corresponded well with below-ground biomass accumulations. Relative soil organic nitrogen accumulations were similar to respective SOC increases. Mean annual SOC accumulation was 475 kg/ha per year. Thus, SOC can be accumulated in soils converted to forages in Florida, and will be proportional to below-ground biomass accumulation. Effects of rising CO2 on SOC increase will be more pronounced for C3 plants than C4 plants.


Effects of Elevated Temperature and CO2 on Seed Quality and Composition of Annual Peanut

J. M. G. Thomas*, K. J. Boote, P. V. V. Prasad, and L. H. Allen, Jr., Univ. of Florida

Seed quality and composition are important aspects of peanut that may be influenced by climate change. The objective of this study was to determine effects of elevated temperature and CO2 upon oil concentration, fatty acid composition of the oil, and subsequent germination and seedling vigor of seed produced. Annual peanut, cultivar Georgia Green, was grown in naturally sunlit, environmentally controlled chambers at four temperatures, 32/22, 36/26, 40/30 and 44/34oC (daytime maximum /nighttime minimum), and two levels of CO2, 350 and 700 μmol mol-1. Standard paper towel germination tests were conducted at 25oC, and percent germination, shoot and root lengths of the seedlings, and seedling weights were measured. Field soil germination tests were conducted. Percent germination and rate of germination were observed. Seedling growth stage, leaf area, and mass of leaf, stem, and root were determined at 14 and 21 days. Seed were analyzed for oil concentration, and fatty acid composition of the oil was assessed using gas chromatography. The paper towel test revealed no differences in seed germination; however, the field germination showed that seedling mass decreased significantly as temperature during seed production increased. There were no differences in seed germination due to CO2. Oil concentration was highest at 36/26 and 40/30°C. As temperature increased, oleic acid increased while the linoleic acid decreased, but there were no effects of CO2. Thus, production temperature of peanut affects seedling vigor as well as seed composition.

*J. M. G. Thomas, 352-374-5891, [email protected] .

Environmental Quality Fractional Distribution of Phosphorus in Histosols Amended with Increasing

Phosphorus Rates Y. Luo*, R. Muchovej, R. W. Rice, and J. M. Shine, Jr., Univ. of Florida

An increased understanding of native soil-P fractions and conversion dynamics between different fractions following P inputs will support on-going efforts to refine P fertilizer recommendations for crops grown in the Everglades Agricultural Area. The objective of this study was to quantify native soil-P fractions in three Everglades Histosols previously cropped to sugarcane, and characterize P-fraction responses following the addition of P fertilizer. In the laboratory, samples were amended with P at 5 different rates (0, 15, 30, 45, and 60 kg P ha-1). The readily available labile inorganic P (Pi) was the highest for Torry (Euic, hyperthermic Typic Haplosaprist), followed by Dania (Euic, hyperthermic Hemic Haplosaprist) and Pahokee (Euic, hyperthermic Lithic Haplosaprist) (41-72, 13-17, and 6-11 mg NaHCO3-Pi kg-1, respectively). However, the labile organic P (Po) was the highest for Pahokee (50-85 mg NaHCO3-Po kg-1), indicating a larger capacity of readily available P in this soil. Torry also had the highest moderately labile P (372-624 mg HCl-P kg-1 or half of the total soil-P pool), which was roughly 4 times greater than for Pahokee. NaOH-P represented 41-51% of the total soil-P pool for Dania and Pahokee as compared with




24-26% for the Torry soil. Residue P (unavailable fraction) was quantified at 10 to 22% for the three organic soils. Application of P fertilizer increased labile and HCl-P fractions while NaOH-P was not affected, indicating that P fertilizer was incorporated into HCl-P (Ca-/Mg-bound P) fractions, a P pool that would eventually become available to long season crops such as sugarcane.

*Y. Luo, 561-993-1500 ext. 1567, [email protected] .

Cropping Effect on the Chemical and Physical Properties of a Typical Organic Soil in the Everglades Agricultural Area

J. L. Pantoja, S. H. Daroub, O. A. Díaz, M. Chen*, and V. Nadal, Univ. of Florida

Cropping practices are important factors affecting soil variability in the organic soils of the Everglades Agricultural Area. The objective of this study was to compare the impact of cropping practices on selected chemical and physical properties of sugarcane, vegetable and virgin (uncultivated and unfertilized) fields located at the Everglades Research and Education Center. Soil samples from the surface 15-cm of each field were taken using a triangular grid sampling plan. All samples were analyzed for bulk density, moisture, organic matter (OM) content, pH, total P, water extractable P (Pw), acid extractable P (Pa), Ca, Mg, K and Si. Correlation, ANOVA, factorial analyses and contour mapping were used to analyze the data. Soil pH increased significantly from 5.1 to 7.0 for the vegetable and sugarcane fields compared to the virgin field. Total P, Pw, Pa, and acid extractable Ca, Mg and Si were also significantly increased in the cropped fields. The lowest soil depth (0.4 m), however, was found in the virgin and sugarcane fields. The shallow depth of the virgin field is probably due to the low water table maintained in that field and lack of irrigation. We hypothesize that the change in properties in the cropped fields are due to an array of factors mainly mixing of mineral material from bedrock and roads, OM oxidation, water management including irrigation and depth of water table, and fertilization practices. Contour maps showed that the virgin field had the lowest variability in the majority of the properties measured.

*M. Chen, 561-993-1527, [email protected] .

Arsenic Uptake Released from CCA Treated Lumber by Florida Vegetable Crops A. Shiralipour* and R.N. Gallaher, Univ. of Florida

Limited information exists about the absorption of inorganic arsenic by the edible parts of vegetables grown in raised beds, near fences or around decks built with the CCA-treated wood. This study intends to provide experimental data to evaluate concerns about the possible exposure to arsenic from gardening use of CCA-treated lumber. In particular, the effect of CCA-treated lumber on vegetables grown near the fences or in raised beds made from the material was investigated under Florida's climate and soil conditions. The final results could be used to develop an exposure model for the risk assessment of the use of CCA in a garden environment. The results of first year experiments indicated that arsenic absorption from soil varies among vegetable crops tested (leaf lettuce, turnip greens, carrots and broccoli) both in Gainesville and Palm Beach. In general, crops absorbed more arsenic when soil arsenic content was higher. Arsenic content in soil was a function of distance from CCA-treated fences; therefore, plants grown closer to fences absorbed more arsenic.

*A. Shiralipour, 352-392-1823 ext. 211, [email protected] .

Environmental Effects of Pesticide Use within Lake Victoria Basin, Uganda J. Wasswa*, B. Kiremire, and P. Nkedi-Kizza, Univ. of Makerere, Uganda

Concern about the environmental and health effects of pesticide use have increased over the past several decades. This concern is evident from the increase in research on the environmental impacts of pesticides in the developed world. Unfortunately, research of this type is sparse in developing countries despite rampant overuse and misuse of pesticides in these countries. This study gives an overview of the findings on pesticide use, policy and residue levels in Uganda with particular emphasis on Lake Victoria. Pesticide residues were analyzed in fish and sediment samples collected from various sites of the Ugandan side of the lake. Three fish species (Nile perch, Tilapia and mudfish) were studied due to differences in their feeding habits. Pesticide residue analysis was done using Gas Chromatography equipped with an Electron Capture Detector (ECD) and a Nitrogen Phosphorous Detector (NPD). Inter-laboratory tests were conducted based on a dual column confirmatory approach. Sediment samples had more frequent detections (70% of samples) and higher levels of





endosulphan sulfate, lindane isomers heptachlor epoxide, DDTs than did fish samples (48 % of the samples). Chlorpyrifos and chlorfenviphos were detected only in sediment samples at levels ranging from 0.52 to 31.2µg/kg. The study also, exposed presence of pesticides aldrin and heptachlor in the sediment, which are not registered for use in the country. Based on fat content, pesticide residues in fish were below the MRLs for fish or mammalian meat established by Environmental Protection Agency (EPA, USA).

*J. Wasswa, [email protected] or [email protected] .

Nematology—Plant Pathology

Susceptibility of Cut Flowers to the Root-knot Nematode, Meloidogyne incognita. K.-H., Wang* and R. McSorley, Univ. of Florida

Many cut flower growers in Florida produce crops directly in the field, subjecting cut flowers to soil-borne diseases and root-knot nematode infection. Seven cultivars of cut flowers were tested for their susceptibility to two races of southern root-knot nematodes (Meloidogyne incognita) in a greenhouse. Cultivars tested were ‘Potomac Royal’ snapdragon (Antirrhinum majus), ‘Madonna Blue’ blue lace flower (Didiscus caeruleus), ‘Green Mist’ and ‘Queen of Africa’ white dill (Ammi majus), ‘Qis White Cut’ larkspur (Consolida ajacis), and ‘Avila Rose Rim’ and ‘Echo Pink’ lisianthus (Eustoma grandiflorum). Cultivars of lisianthus and larkspur tested were relatively poor hosts to M. incognita races 1 and 2 as compared to the known susceptible host, snapdragon (P < 0.05). Based on number of nematodes extracted per gram of root tissue, ‘Madonna Blue’ blue lace flower was more (P < 0.05) susceptible, ‘Green Mist’ white dill was equally susceptible, and ‘Queen of Africa’ white dill was less susceptible than snapdragon (P < 0.05). Numbers of nematode per gram of root for M. incognita race 1 and 2 were not different (P > 0.05) on any plant cultivar. Despite differences in nematode susceptibility, numbers of flowers, and shoot and root weights of all cultivars tested except ‘Madonna Blue’ were not affected by nematode inoculation. M. incognita race 1 reduced the number of flower buds and shoot weight of ‘Madonna Blue’ compared to the control. Results indicated that blue lace flower and white dill are very susceptible to M. incognita.

*K.-H., Wang, 352-392-1901 ext. 197, [email protected] .




Soil and Crop Science Society of Florida

68

SOCIETY AFFAIRS

2005 PROGRAM SOIL AND CROP SCIENCE SOCIETY OF FLORIDA

AND FLORIDA NEMATOLOGY FORUM

SIXTY-FIFTH ANNUAL MEETING

18 – 20 May 2005

Doubletree Guest Suites Boca Raton, FL

SOCIETY OFFICERS

President……………………………………………………………………………………...Bill Thomas

President–Elect and Program Chairman………….....................................................................Ken Boote Past President……………………..…………………………………………………….Carrol Chambliss Secretary–Treasurer………………………………………………………………………Thomas Obreza Director…………………………………….…………..………………………………..…..Martin Adjei Director……………………………………..…………………………………………………...Lena Ma Director……………………………………………………………………………….....Greg McDonald Proceedings Editor……………………………………………………………………...Rob Kalmbacher

2005 PROGRAM SUMMARY

Wednesday, 18 May 2005

Time Event Room 8:00 AM Registration begins Hotel Lobby

8:15 AM-4:30 PM Opening Session and County Agent In-Service Training: Everglades Restoration: Getting Involved in the Educational Process

Coral Springs Room

5:00 PM Board Meeting Boca West Room 6:30 PM Reception Jamaica Bay Room

Thursday, 19 May 2005

Time Event Room 8:00 AM Registration continues Hotel Lobby 8:30 AM Paper sessions: Graduate Student Forum Coral Springs Room11:00 AM Business meeting Coral Springs Room1:30 PM Paper sessions: Crops and Fertilization Practices Coral Springs Room6:30 PM Banquet and Awards Jamaica Bay Room

Friday, 20 May 2005

Time Event Room 8:15 AM Paper sessions: Climate Change Effects Coral Springs Room9:00 AM Paper sessions: Environmental Quality Coral Springs Room11:00 AM Paper sessions: Nematology-Plant Pathology Coral Springs Room11:30 AM Nematology Forum Coral Springs Room


2005 SESSIONS

Opening Session and County Agent In-Service Training, Wednesday AM-PM, 18 May 2005

Everglades Restoration: Getting Involved in the Educational Process

Opening remarks; Educational influence of county agents in counties affected by CERP – Tom Obreza, Soil and Water Science Department, University of Florida, Gainesville.

What are the problems in the Everglades watershed, and why are we “restoring” it? – Stan Bronson, Florida EARTH Foundation, West Palm Beach

Everglades ecology: Then and now – Mark Clark, Soil and Water Science Department, University of Florida, Gainesville. Everglades replumbing: Decompartmentalizing the surface flow – Fred Sklar, South Florida Water Management District,

West Palm Beach Ecosystem restoration in the Hole-in-the-donut – Lauren Serra, National Park Service, Everglades National Park,

Homestead How aquifer storage and recovery (ASR) will expand future water supply – Rick Nevulis, South Florida Water

Management District, West Palm Beach Research in support of the Everglades P water quality standard – Sue Newman, South Florida Water Management

District, West Palm Beach Phosphorus origin, transport, management, and BMPs: Kissimmee River Basin – Don Graetz, Soil and Water Science

Department, University of Florida, Gainesville Phosphorus origin, transport, management, and BMPs: Everglades Agricultural Area – Samira Daroub, Everglades

REC, University of Florida, Belle Glade Phosphorus origin, transport, management, and BMPs: C-139 Basin – Sanjay Shukla, Southwest Florida REC,

University of Florida, Immokalee Phosphorus origin, transport, management, and BMPs: Urban areas – Mark Clark, Soil and Water Science Department,

University of Florida, Gainesville Cleaning up the drainage water: Stormwater treatment areas (STAs) – Jana Newman, South Florida Water Management

District, West Palm Beach

2005 GRADUATE STUDENT FORUM PAPER SESSIONS

Thursday AM, 19 May 2005

Transport of water, N-forms, and potassium through plastic mulched beds cropped with vegetables under drip irrigation – K. A. Mahmoud*, P. Nkedi-Kizza, J. B. Sartain, E. H. Simonne, M. D. Dukes, and R. S. Mansell

Agronomic impact of land applied water treatment residuals (WTR): Soil test methods and application rates – O. O. Oladeji*, J. B. Sartain, and G. A. O’Connor

Chemical characterization and mineralization rates of selected biosolids and organic wastes – C. B. Reis*, J. B. Sartain, J. E. Rechcigl, C. D. Stanley, and M. B. Adjei

Characterization of sorption of pesticides applied to carbonatic soils of south Florida and Puerto Rico – G. Kasozi*, P. Nkedi-Kizza, W. Harris, Y. Li, D. Hodell, and D. Powell

Capillary fringe associated with hydrologic soil indicators at Sandhill Lakes – T. C. Richardson* and P. Nkedi-Kizza Evaluation of nitrogen release patterns from controlled-release fertilizers for citrus production – C. Medina*, T.

Obreza, and J. B. Sartain St. Augustine grass phosphorus requirement using hydroponic culture – M. Liu*, J. B. Sartain, G. L. Miller, W. G.

Harris, P. Nkedi-Kizza, and R. L. Wu Application of DSSAT for simulating nitrogen response of sweet corn – C. M. Cherr*, J. M. S. Scholberg, K. J. Boote,

and M. D. Dukes

2005 PAPER SESSIONS

Thursday PM, 19 May 2005

Crops & Fertilization Practices

Determining ammonium and nitrate using a gas sensing ammonia electrode – D. W. Rich*, B. Grigg, and G. H. Snyder Nitrogen fertilization of rice in Florida – G. H. Snyder*


70

Crops & Fertilization Practices - continued

Interactive effect of P and N rates on leaf anthocyanins, tissue nutrient concentrations, and dry matter yield of Floralta limpograss during short day-length – N. Shaikh*, M. B. Adjei, and J. M. Scholberg

Biomass yield and forage nutritive value of Cynodon grasses harvested monthly in central Florida – P. Mislevy* and F. G. Martin

Forage yield and nutritive value of Urochloa varieties in Southwest Florida – R. M. Muchovej, P. R. Newman, I. V. Ezenwa*

Elevated CO2 and temperature effects on sugarcane plant and ratoon crops – L. H. Allen, Jr.*, J. C. V. Vu, J. C. Anderson, and J. D. Ray

Effect of irrigation and gypsum application on aflatoxin accumulation in peanuts – P. J. Wiatrak*, D. L. Wright, J. J. Marois, and D. Wilson

Integration and verification of water quality and crop growth models for BMP planning – K. J. Boote*, J. W. Jones, and B. M. Jacobson

Simulating crop N balance in crop growth models used for Best Management Practice recommendations – J. I. Lizaso*, K. J. Boote, J. W. Jones, and W. D. Batchelor

Thermal units prediction for chilling accumulation and crop development in Alabama, Florida and Georgia – J. Bellow* and C. Fraisse

Germination and vigor of peanut seed from six cultivars as affected by production and storage location – J. M. G. Thomas*, K. J. Boote, and D. W. Gorbet

Measurement of plant-produced volatile organic compounds in controlled environments – O. Monje*, I. Eraso, J. T. Richards, J. S. Sager, and T. P. Griffin

Friday AM, 19 May 2005

Climate Change Effects

Elevated temperature decreases yields of seed grain crops – L. H. Allen, Jr.*, K. J. Boote, P. V. V. Prasad, R. W. Gesch, A. M. Snyder, J. M. G. Thomas, and J. C. V. Vu

Soil carbon sequestration potentials of bahiagrass and rhizome perennial peanut in Florida under current and global warming conditions – L. H. Allen, Jr.*, K. J. Boote, J. M. G. Thomas, S. L. Albrecht, and K. W. Skirvin

Effects of elevated temperature and CO2 on seed quality and composition of annual peanut – J. M. G. Thomas*, K. J. Boote, P. V. V. Prasad, and L. H. Allen, Jr.

Environmental Quality

Effects of reclaimed municipal waste water on horticultural ratings, fruit quality, and soil and leaf mineral content of citrus grown in central Florida – K. T. Morgan* and T. A. Wheaton

Cropping effect on chemical and physical properties of a typical organic soil in the Everglades Agricultural Area – J. L. Pantoja, S. H. Daroub, O. A. Diaz, M. Chen*, and V. Nadal

Implementation of phosphorus load reducing BMPs on an Everglades Agricultural Area farm – J. Menhennett* and T. A. Lang

Fractional distribution of phosphorus in Histosols amended with increasing phosphorus rates – Y. Luo*, R. M. Muchovej, R. W. Rice, and J. M. Shine

Commercial microbial inocula and their effect on plant growth and development: A synopsis of current literature and case studies – P. K. Kalogridis*, J. M. Scholberg, R. McGovern, and K. L. Buhr

Environmental effects of pesticide use within Lake Victoria Basin, Uganda – J. Wasswa*, B. Kiremire, and P. Nkedi-Kizza

Arsenic uptake released from CCA treated lumber by Florida vegetable crops – A. Shiralipour* and R. N. Gallaher Nematology-Plant Pathology

Effect of fungicide schedule on defoliation of ‘Valencia’ orange by Mycosphaerella citri in Southwest Florida – R. J. McGovern*, A. A. Stoddard III, and B. M. Cawley

Susceptibiliity of four cut flowers to root-knot nematode, Meloidogyne incognita – K-H. Wang* and R. McSorley


Soil and Crop Science Society of Florida Executive Board Meeting McCarty Hall, Univ. of Florida, Gainesville

27 January 2005

William D. Thomas, President

Individuals present: Bill Thomas, Ken Boote, Lena Ma,

Greg Means, Tom Obreza.

Bill Thomas called the meeting to order at 3:15 PM. Tom Obreza distributed minutes from the board meeting held on 12 October 2004. No changes were suggested following a review by the group, so they were accepted by the board.

Bill Thomas stated that he was pleased with the improvements made to the SCSSF web site by Greg Means. Other than a minor glitch with the “return to home” button, the site looks better than ever and works well.

The rest of the discussion centered on the upcoming 2005 annual meeting in Boca Raton, May 18-20:

Tom Obreza summarized the extension in-service training on Everglades restoration that will occur on May 17-18. On the first day the attendees will tour a portion of the Everglades, including Stormwater Treatment Area #1 and an agricultural operation where BMPs have been implemented to reduce P loss. The second day will be a symposium titled “Everglades Restoration: Getting Involved in the Educational Process” that doubles as the opening session of the annual meeting. Tom will be setting up the entire Wednesday program (May 18), so paper titles sent to Ken will be scheduled on Thursday and Friday. The grad student paper contest will be scheduled for Thursday morning.

Content of the first call for papers was discussed. The board decided that we would require an abstract for all volunteered papers this year, so a statement indicating same will be added to the paper title submission form. The format for abstracts should be the typical single paragraph with a 250-word limit. Ken Boote made a motion to set an abstract deadline of April 30

th. The motion was seconded

and it passed unanimously. The board requested that the call for papers be sent IFAS-wide. Tom Obreza said both the first and second calls would be sent electronically using the IFAS-ALL e-mail list-serve.

Procedures for the graduate student paper contest were reviewed to make sure they were understood by all.

The Editorship of the society is still up in the air. Rob Kalmbacher will be finishing Volume 64 (2004 annual meeting) in the next few months, but this will be his last effort. We have no Editor waiting to take over at present. Several names were suggested as possibilities, including Larry Duncan, Bob Mansell, and David Calvert. An informal search committee was formed by Ken Boote to approach these individuals and determine their interest in becoming our next Editor.

Bill Thomas brought up the subject of possibly arranging extracurricular activities like golf or fishing, but no firm plans were made to do this.

The meeting was adjourned at 4:18 PM.

Soil and Crop Science Society of Florida Executive Board Meeting

Doubletree Hotel, Boca Raton, FL 18 May 2005

Individuals present: Ken Boote, Greg McDonald, Bill Thomas, Martin Adjei, Kelly Morgan, Tom Obreza

Bill Thomas called the meeting to order at 5:06 PM. Tom Obreza distributed minutes from the three previous board meetings (May and October, 2004; January 2005). No changes were suggested following review, so they were accepted unanimously by the board.

Tom Obreza gave the Treasurer’s report for the fiscal year 2003-2004. Even though the 2004-2005 year was almost through, a complete report cannot be compiled until after June 2005. The 2003-2004 report still needs to be reviewed by the Audit committee. David Calvert is the head of this committee, but he has been difficult to contact since retirement. After some discussion, the Treasurer’s report was accepted unanimously by the board.

The necrology report was submitted by committee chair Ken Quesenberry. Individuals who passed away


72

since the 2004 SCSSF meeting included Mr. David W. Jones and Dr. Carrol B. Chambliss.

Dedication of Proceedings/Life Member committee chair Craig Stanley submitted a written copy of his committee’s nominations. They recommended that volume 65 of the SCSSF Proceedings be dedicated to Dr. Brian McNeal. They also recommended that Dr. Fred Rhoads, Dr. David Calvert, and Dr. Grover Smart be honored with lifetime membership in the Society.

Jerry Sartain did not provide a written Graduate Student Committee report, but will deliver his message at the business meeting.

An Editor’s report was submitted by Rob Kalmbacher. There were 24 manuscripts submitted for volume 64 of the SCSSF Proceedings. Seven were for out-of-state review, and four were accepted (all in the Soils and Environmental section). Three authors withdrew their manuscripts. In the non-refereed category, there are eight manuscripts in Crops, five additional Soils and Environmental manuscripts, and four Nematology-Entomology manuscripts for a grand total of 21. The entire volume 64 was sent to Painter Printing the previous week for galley proofs. The Editorial board included Ed Hanlon and Don Graetz (Soils and Environmental Quality), Martin Adjei and Ray Gallaher (Crops) and Larry Duncan (Nematology-Entomology). Rob indicated that without these people, we would not have a Proceedings.

Martin Adjei asked if we would publish abstracts alone in the Proceedings for the coming year, and the answer was yes. More specifically, the abstract will be published if it is the only written material submitted, but if a paper is submitted later then the abstract will be pulled in lieu of the full paper. The question of refereed abstracts came up again with no concrete resolution.

Bill Thomas has been searching for a replacement Editor since Rob Kalmbacher announced that Proceedings volume 64 would be his last. He has asked quite a few people, but received no positive responses. The Society has reached an impasse in this search with no good solution. It was decided to ask the membership at the business to suggest additional people to ask.

Ken Boote gave the 2005 program update. He indicated that the Society is not aggressive enough in calling for papers. Other than that, the deadline dates were good, abstract submission was good, and the program planning process went fine. Having only a single session throughout the meeting this year is working well.

The Membership committee of Ken Boote, Alex Csizinszky, and Hartwell Allen submitted a one-page report and statement addressing the issue of waning membership numbers. This statement is too lengthy to summarize here and is attached. Questions about publishing in the Proceedings came up, e.g. must an author

present a paper at the annual meeting in order to publish? This question will be brought up at the business meeting. Other attempts at publicity could include using the ASA-CSSA-SSSA website, and joining with Georgia Plant Food people to recruit new authors and members.

New officers: At the upcoming business meeting, the Nominating committee headed by Craig Stanley will nominate Dr. Martin Adjei for President Elect and Program Chair. The committee asked Dr. Samira Daroub if she would become the new at-large board member, but have not yet received a response.

A discussion ensued about “partially” merging with the Florida State Horticultural Society, particularly in terms of meeting together. It was decided that Ken Boote and Tom Obreza will approach FSHS officers about this at their June 2005 meeting in Tampa.

Bill Thomas indicated that this would be a good time to update the SCSSF Operations Manual.


Soil and Crop Science Society of Florida Business Meeting

Doubletree Hotel, Boca Raton, FL 19 May 2005

Bill Thomas called the meeting to order at 11:15 AM. The first order of business was to review the minutes from the last business meeting, held in Tallahassee in May, 2004. After review by the members present, a motion to accept the minutes was made and seconded. A vote was taken and it passed unanimously.

Tom Obreza read the Treasurer’s report. The membership accepted it by unanimous vote. Tom Obreza indicated the Audit committee report would be delayed due to difficulty communicating with David Calvert.

Tom Obreza read the Editor’s report submitted by retiring Editor Rob Kalmbacher. There were 24 manuscripts submitted for volume 64 of the SCSSF Proceedings. Seven were for out-of-state review, and four were accepted (all in the Soils and Environmental section). Three authors withdrew their manuscripts. In the non-refereed category, there are eight manuscripts in Crops, five additional Soils and Environmental manuscripts, and four Nematology-Entomology manuscripts for a grand total of 21. The entire volume 64 was sent to Painter Printing the previous week for galley proofs. The Editorial board included Ed Hanlon and Don Graetz (Soils and Environmental Quality), Martin Adjei and Ray Gallaher (Crops) and Larry Duncan (Nematology-Entomology). Rob indicated that without these people, we would not have a Proceedings.

Ken Boote commented on the difficulty the Society is having trying to find a new Editor. He has asked a lot of


people, with no takers. He asked if anyone present would volunteer to take over this position, but again had no luck. A motion to accept the Editor’s report was made and seconded, and it passed unanimously.

Jerry Sartain discussed the graduate student competition, and reiterated Society concerns about low attendance and participation. The SCSSF meeting is a great place to train students, and we need to coax more to come. Awards for the paper contest will be presented this evening at the banquet.

The Necrology committee report submitted by Ken Quesenberry was read. Individuals who passed away since the 2004 SCSSF meeting included Mr. David W. Jones and Dr. Carrol B. Chambliss.

The Dedication of Proceedings/Life Member committee report submitted by Craig Stanley was read. The committee recommended that volume 65 of the SCSSF Proceedings be dedicated to Dr. Brian McNeal. They also recommended that Dr. Fred Rhoads, Dr. David Calvert, and Dr. Grover Smart be honored with lifetime membership in the society. A motion was made and seconded to accept these nominations, and the membership vote was unanimously positive.

Ken Boote gave a report as this year’s program chair. The system to receive titles and abstracts worked well and participants did a good job of meeting deadlines. Ken also lauded the site selection committee for a job well done. He indicated that we could have done a better job of publicizing the meeting. Our numbers are about the lowest they have ever been.

The next item on the agenda was a discussion of membership led by Ken Boote. Ken opened the discussion by suggesting that the message to faculty of only publishing in the highest-level scientific journals has been carried too far, and that these journals have been given too much importance to the detriment of a state/regional Proceedings. Most people would agree that advising new faculty to strive for the best journals is sound, but it has kept more seasoned faculty away. Somehow the message that it is still OK to publish in the Proceedings needs to be disseminated and become accepted once again. Paul Mislevy stated his belief that not all science being done in our region is getting published in national journals, and that everyone probably has material that could and should be published in the Proceedings. Ken Boote suggested that we encourage participation from people outside the state of Florida because we might pick up some additional members (see attached Membership Committee report). It was pointed out that non-Floridians can publish now as long as they present their paper as well. That point led to the next question asked, which was, can or should we

accept, review, and publish papers if they are not presented at an annual meeting? Jerry Sartain asked how we would get this opportunity advertised if it was acceptable to the Society. Ken Boote suggested the ASA website as a possibility. Others suggested department chairs and Georgia Plant Food as information outlets.

Other ideas about augmenting participation membership: Bob McGovern asked if we could mesh with the southern branch of the ASA. In response to this idea, George Snyder asked if someone who presented at the southern branch ASA meeting could publish that paper in the Proceedings. Hartwell Allen suggested putting our information on ASA’s web site. Jerry Sartain moved to accept George Snyder’s suggestion about connecting the southern branch ASA to the SCSSF Proceedings. The motion was seconded, and the vote was unanimously positive.

Ken Boote brought up the idea of another joint meeting with the Florida State Horticultural Society in 2006. The advantages would be reduction in meeting cost and administrative duties. Ken Boote, Tom Obreza, and Kelly Morgan will meet with George Hochmuth (FSHS President) at the FSHS annual meeting in June to discuss this possibility.

Jerry Sartain made a motion to have the SCSSF Board of Directors consider allowing non-presented papers to be published in the Proceedings. This motion was seconded and the vote was unanimously positive.

The Nominating Committee’s recommendations were stated as follows: Dr. Martin Adjei for President-Elect and 2006 Program Chairman, and Samira Daroub for at-large board member. There were no further nominations from the floor, and nominations were closed. A motion was made by Jerry Sartain to accept the candidates by acclimation. This motion was seconded, and it carried unanimously.

Bill Thomas reminded everyone once again that we still need a new Editor, and he wants to hear from a volunteer. Other items from Bill Thomas: The SCSSF website has been updated and is functional; the operations manual needs updating, especially the timelines.

The final item for discussion was potential locations for future meetings. Some members requested meeting sites closer to Gainesville. Site selection chairmen for the next 2 years will be Jerry Sartain and Paul Mislevy. We could potentially meet with FSHS in Tampa. It will likely take 2 years to merge meetings with them if the Society so desires.



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SOIL AND CROP SCIENCE SOCIETY OF FLORIDA FINANCIAL REPORT July 1, 2004 through June 30, 2005

ASSETS IN BANK (July 01, 2004) Checking Account - Bank of America ..................................................................................................................................................................................................10164.19 Certificate of Deposit - Bank of America (300 000 7062 2783) ..........................................................................................................................................................12229.20 Total in Bank......................................................................................................................................................................................................................22393.39

RECEIPTS Dues………. ..............................................................................................................................................................................................................................................810.00 Sale of Proceedings .................................................................................................................................................................................................................................1290.00 Page Charges, Volume 63 .......................................................................................................................................................................................................................4713.90 Annual Meetings......................................................................................................................................................................................................................................2495.00 Banquet tickets ………………………………………….120.00 Registration …………………………………………….2375.00 Interest……… .............................................................................................................................................................................................................................................99.61 Certificate of Deposit (300 000 7062 2783)……………90.47 Checking Account Interest.…………………..………….9.14 Total Receipts…………..........................................................................................................................................................................................................................9408.51

DISBURSEMENTS Prior year’s expense...................................................................................................................................................................................................................................144.26 Printing SCSSF Proceedings Vol 63 .......................................................................................................................................................................................................6856.87 Postage………….......................................................................................................................................................................................................................................689.25 Checking account service charge ................................................................................................................................................................................................................16.00 Annual Meeting Expenses Meeting rooms..........................................................................................................................................................................................................................90.00 Breaks………….....................................................................................................................................................................................................................805.00 Hotel service charges .............................................................................................................................................................................................................517.92 Grad student awards ...............................................................................................................................................................................................................600.00 Grad student hotel rooms .......................................................................................................................................................................................................828.80 Reception………....................................................................................................................................................................................................................545.00 Awards banquet....................................................................................................................................................................................................................1149.60 Awards hardware......................................................................................................................................................................................................................50.84 Clerical expenses....................................................................................................................................................................................................................355.52 Meeting sales tax....................................................................................................................................................................................................................168.33 Office Supplies ............................................................................................................................................................................................................................................88.34 Annual license fee to Florida Dept of State ................................................................................................................................................................................................61.25 Total disbursements ...............................................................................................................................................................................................................................12966.98

ASSETS IN BANK (June 30, 2005) Checking Account - Bank of America.................................................................................................................................................................................6515.25 Certificate of Deposit - Bank of America (300 000 7062 2783) .......................................................................................................................................12319.67 Total in Bank......................................................................................................................................................................................................................18834.92

2006 COMMITTEES

(Date in parenthesis indicates year each member rotates-off after the annual meeting.)

Audit Rao Mylavarapu (2006) Ken Quesenberry (2007) Larry Duncan (2008)

Nominating

Craig Stanley (2006) Ken Quesenberry (2007) Bill Thomas (2008)

Necrology

David Wright (2006) Jerry Bennett (2007) Ed Hanlon (2008)

Dedication of Proceedings and Honorary Lifetime Member Selection

Hartwell Allen (2006) George O'Connor (2007) Lynn Sollenberger (2008)

Membership Vacant (2006) William Crow (2006) Robert McGovern (2007) Oghenekome Onokpise (2007) Ken Quesenberry (2008) Peter Nkedi-Kizza (2008)

Graduate Student Presentation Contest

Gilbert Sigua (2006) Mimi Williams (2006) Anne Blount (2007) Craig Stanley (2007) Mark Clark (2008) Vimala Nair (2008)

Site Selection- Local Arrangements

Jerry Sartain (2006) Paul Mislevy (2007) Jack Rechcigl (2008)


MEMBERSHIP LISTS

Regular Members 2005 MARTIN B. ADJEI RANGE CATTLE REC-ONA 3401 EXPERIMENT STATION ONA, FL 33865-9706

KENNETH L. CAMPBELL UNIVERSITY OF FLORIDA P.O. BOX 110570 GAINESVILLE, FL 32611-0570

RAYMOND GALLAHER UNIVERSITY OF FLORIDA P.O. BOX 110730 GAINESVILLE, FL 32611-0730

L. H. ALLEN UNIVERSITY OF FLORIDA P.O. BOX 110965 GAINESVILLE, FL 32611-0965

CARROLL CHAMBLISS UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

MARIA GALLO-MEAGHER UNIVERSITY OF FLORIDA P.O. BOX 110300 GAINESVILLE, FL 32611-0300

D. D. BALTENSPERGER UNIVERSITY OF NEBRASKA 4502 AVE. I SCOTTSBLUFF, NE 69361-4939

MING CHEN EVERGLADES REC P.O. BOX 8003 BELLE GLADE, FL 33430

CASSEL S. GARDNER FLORIDA A&M UNIVERSITY AGRON PROG & CEN FOR WATER QUAL PERRY-PAIGE BLDG SOUTH, RM 202J TALLAHASSEE, FL 32307

IIAN BAR NETAFIM USA 116 BEUFORT DR. LONGWOOD, FL 32779

WILLIAM CROW UNIVERSITY OF FLORIDA P.O. BOX 110620 GAINESVILLE, FL 32611-0620

ROBERT GILBERT EVERGLADES REC P.O. BOX 8003 BELLE GLADE, FL 33430

RAY BASSETT AGLIME SALES, INC. 1375 THORNBURG ROAD BABSON PARK, FL 33827

A. A. CSIZINSKY GULF COAST REC 5007 60 STREET EAST BRADENTON, FL 34203-9324

BARRY GLAZ USDA-ARS 12990 US HIGHWAY 441 CANAL POINT, FL 33438

JERRY M. BENNETT UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

SAMIRA DAROUB EVERGLADES REC 3200 E. PALM BEACH RD BELLE GLADE, FL 33430

D. W. GORBET NORTH FLORIDA REC 3925 HIGHWAY 71 MARIANNA, FL 32446

D. A. BERGER NORTH FLORIDA REC 55 RESEARCH RD. QUINCY, FL 32351-5677

DONALD W. DICKSON UNIVERSITY OF FLORIDA P.O. BOX 110630 GAINESVILLE, FL 32611-0630

EDWARD A. HANLON SOUTHWEST FLORIDA REC 2686 SR 29 NORTH IMMOKALEE, FL 33438

KENNETH J. BOOTE UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

SPENCER G. DOUGLASS DOUGLASS FERTILIZER 1180 SPRING CENTER BLVD. ALTAMONTE SPRINGS, FL 32714

ZHENLI HE INDIAN RIVER REC 2199 SOUTH ROCK ROAD FT. PIERCE, FL 34945

BARRYJ. BRECKE WEST FLORIDA REC 5988 HWY 90, BLDG 4900 MILTON, FL 32583

MICHAEL DUKES UNIVERSITY OF FLORIDA P.O. BOX 110570 GAINESVILLE, FL 32611-070

GEORGE J. HOCHMUTH NORTH FLORIDA REC 155 RESEARCH ROAD QUINCY, FL 32351-5677

JACQUE W. BREMAN ROUTE 3, BOX 299 LAKE BUTLER, FL 32054

LARRY DUNCAN CITRUS REC 700 EXPERIMENT STATION ROAD LAKE ALFRED, FL 33850-2299

EDWARD W. HOPWOOD, JR. 5200 NW 62ND COURT GAINESVILLE, FL 32653

ERIC C. BREVIK VALDOSTA STATE UNIVERSITY DEPT OF PHYSICS, ASTRON & GEOSCIENCE VALDOSTA, GA 31698-0055

JOE EGER DOW AGRO SCIENCES 2606 S. DUNDEE BLVD. TAMPA, FL 33629

R. N. INSERRA UNIVERSITY OF FLORIDA P.O. BOX 147100 GAINESVILLE, FL 32614-7100

J. B. BROLMANN 2914 FOREST TERRACE FT. PIERCE, FL 34982

IKE EZENWA RANGE CATTLE REC 3401 EXPERIMENT STATION ONA, FL 33865-9706

JENNIFER M. JACOBS UNIVERSITY OF FLORIDA P.O. BOX 116580 GAINESVILLE, FL 32611-6580

ROBIN BRYANT TROPICANA INC. 1001 13TH AVE. EAST BRADENTON, FL 34208

JAMES FERGUSON UNIVERSITY OF FLORIDA P.O. BOX 110690 GAINESVILLE, FL 32611-0690

JAY JAYACHANDRAN FLORIDA INTERNATIONAL UNIV. ENVIRONMENTAL STUDIES DEPT. MIAMI, FL 33199

DAVID V. CALVERT INDIAN RIVER REC 2199 S. ROCK ROAD FT. PIERCE, FL 34945-3138

CLYDE W. FRAISSE UNIVERSITY OF FLORIDA PO BOX 110570 GAINESVILLE, FL 32611-0570

JONATHAN D. JORDAN UNIVERSITY OF FLORIDA P.O. BOX 110570 GAINESVILLE, FL 32611-0570


76

ROBERT S. KALMBACHER RANGE CATTLE REC – ONA 3401 EXPERIMENT STATION ONA, FL 33865-9706

ROBERT MCGOVERN UNIVERSITY OF FLORIDA PLANT MEDICINE PROGRAM P.O. BOX 110680 GAINESVILLE, FL 32611-0680

GEORGE O'CONNOR UNIVERSITY OF FLORIDA P.O. BOX 110510 GAINESVILLE, FL 32611-0510

TAWAINGA KATSVAIRO NORTH FLORIDA REC-QUINCY 155 RESEARCH ROAD QUINCY, FL 32351

ROBERT MCSORLEY UNIVERSITY OF FLORIDA P.O. BOX 110620 GAINESVILLE, FL 32611-0620

OGHENEKOME U. ONOKPISE FLORIDA A & M UNIVERSITY RM 203, SOUTH PERRY-PAIGE BLDG TALLAHASSEE, FL 32307

NANCY KOKALIS-BURELLE USDA-HORT. RES. LAB 2001 S ROCK RD. FT. PIERCE, FL 34945

MARIA DE LOURDES MENDES UNIVERSITY OF FLORIDA PO BOX 110620 GAINESVILLE, FL 32611-0620

YING OUYANG ST. JOHNS RIVER WMD P.O. BOX 1429 PALATKA, FL 32178-1429

THOMAS A. KUCHAREK UNIVERSITY OF FLORIDA P.O. BOX 110680 GAINESVILLE, FL 32611-0680

JOHN MENHENNETT OKEELANTA CORPORATION PO BOX 86 SOUTH BAY, FL 33493

HUGH L. POPENOE UNIVERSITY OF FLORIDA P.O. BOX 110286 GAINESVILLE, FL 32611-0286

ORIE N. LEE 5005 LILLIAN LEE ROAD ST. CLOUD, FL 34771

J. D. MILLER SUGARCANE FIELD STATION STAR ROUTE BOX 8 CANAL POINT, FL 33438

DAVID POWELSON 616 LOTHIAN DR. TALLAHASSEE, FL 32312-2832

PAUL S. LEHMAN DPI/FDACS P.O. BOX 147100 GAINEVILLE, FL 32614-7100

PAUL MISLEVY RANGE CATTLE REC-ONA 3401 EXPERIMENT STATION ONA, FL 33865-9706

KENNETH H. QUESENBERRY UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

YUNCONG LI TROPICAL REC 18905 SW 280 STREET HOMESTEAD, FL 33031

OSCAR MONJE DYNAMAC CORPORATION MAIL CODE DYN-3 KENNEDY SPACE CENTER, FL 32980

JACK RECHCIGL GULF COAST REC 5007 60 STREET E BRADENTON, FL 34203-9324

SALVADORE J. LOCASCIO UNIVERSITY OF FLORIDA P.O. BOX 110690 GAINESVILLE, FL 32611-0690

KELLY MORGAN SOUTHWEST FLORIDA REC 2686 SR 29 N IMMOKALEE, FL 34142-9515

PAUL REITH UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

YIGANG LUO EVERGLADES REC 3200 E PALM ROAD BELLE GLADE, FL 33430

DOLEN MORRIS USDA, SUGARCANE FIELD STATION 12990 HWY 441 CANAL POINT, FL 33438

JERRY B. SARTAIN UNIVERSITY OF FLORIDA P.O. BOX 110510 GAINESVILLE, FL 32611-0510

LENA Q. MA UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611-0290

ROSA M. MUCHOVEJ SOUTHWEST FLORIDA REC 2686 SR 29 NORTH IMMOKALEE, FL 34142-9515

LIESBETH M. SCHMIDT ROUTE 3, BOX 224-10 LAKE CITY, FL 32025

GREG MACDONALD UNIVERSITY OF FLORIDA PO BOX 110500 GAINESVILLE, FL 32611-0500

KENNETH R. MUZYK GOWAN CO 408 LARRIE ELLEN WAY BRANDON, FL 33511

ARNOLD SCHUMANN CITRUS REC 700 EXPERIMENT STATION ROAD LAKE ALFRED, FL 33850-2299

ROBERT MANSELL UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611-0290

RAO MYLAVARAPU UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611

LARRY SCHWANDES 1805 NW 38 TERRACE GAINESVILLE, FL 32605

BRUCE MATHEWS UNIVERSITY OF HAWAII-HILO COLLEGE OF AGRICULTURE 200 W. KAWILI ST HILO, HI 96720-4091

SHAD D. NELSON TEXAS A&M UNIV. – KINGSVILLE MSC 228 KINGSVILLE, TX 78363

CHARLES SEMER UNIVERSITY OF FLORIDA P.O. BOX 110680 GAINESVILLE, FL 32611-0680

V. V. MATICHENKOV INDIAN RIVER REC 2199 SOUTH ROCK ROAD FT. PIERCE, FL 34945

PETER NKEDI-KIZZA UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611-0290

JAMES M. SHINE, JR. SUGAR CANE GROWERS COOP P.O. BOX 666 BELLE GLADE, FL 33430

MABRY MCCRAY EVERGLADES REC 3200 E PALM BEACH ROAD BELLE GLADE, FL 33430

THOMAS A. OBREZA UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611-0290

AZIZ SHIRALIPOUR UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500


KENNETH SHULER 12657 158 STREET NORTH JUPITER, FL 33478

JAMES A. STRICKER P.O. BOX 9005 DRAWER HS03 BARTOW, FL 33831-9005

RALPH W. WHITE 11227 DEAD RIVER ROAD TAVARES, FL 32778

GILBERT SIGUA USDA-ARS 22271 CHINSEGUT HILL ROAD BROOKSVILLE, FL 34601

JEAN M.G. THOMAS UNIVERSITY OF FLORIDA P.O. BOX 110300 GAINESVILLE, FL 32611-0300

E. B. WHITTY UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

GROVER C. SMART, JR. UNIVERSITY OF FLORIDA P.O. BOX 110620 GAINESVILLE, FL 32611-0620

WILLIAM THOMAS COLUMBIA COUNTY EXTENSION RT 18, BOX 720 LAKE CITY, FL 32025

M. J. WILLIAMS USDA-NRCS 2614 NW 43RD STREET GAINESVILLE, FL 34606-6611

GEORGE H. SNYDER EVERGLADES REC P.O. BOX 8003 BELLE GLADE, FL 33430

PAULETTE TOMLINSON BRADFORD COUNTY EXTENSION 2266 NORTH TEMPLE AVE. STARKE, FL 32091-1028

P. J. WIATRAK NORTH FLORIDA REC 155 RESEARCH RD. QUINCY, FL 32351

RAYMOND SNYDER 3101 GULFSTREAM ROAD LAKE WORTH, FL 33461

NOBLE USHERWOOD 1661 APALACHEE RIVER RD. MADISON, GA 30650

ANN C. WILKIE UNIVERSITY OF FLORIDA P.O. BOX 110960 GAINESVILLE, FL 32611-0960

A. R. SOFFES-BLOUNT NORTH FLORIDA REC 3925 HWY 71 MARIANNA, FL 32446-7906

MARK WADE INDIAN RIVER REC 2199 S. ROCK ROAD FT. PIERCE, FL 34945

BOB WILLIAMS DUPONT 10918 BULLRUSH TERR BRADENTON, FL 34202

LYNN E. SOLLENBERGER UNIVERSITY OF FLORIDA P.O. BOX 110300 GAINESVILLE, FL 32611-0300

KOON-HUI WANG UNIVERSITY OF FLORIDA P.O. BOX 110620 GAINESVILLE, FL 32611-0620

T. W. WINSBERG GREEN CAY FARM 12750 HAGEN RANCH RD BOYNTON BEACH, FL 33437

GERADO SOTO 4801 HAMPDEN LANE #704 BETHESDA, MD 208142949

DAVID P. WEINGARTNER HASTINGS REC P.O. BOX 728 HASTINGS, FL 32145-0728

GEORGE WINSLOW GULF CITRUS MANAGEMENT, INC P.O. BOX 512116 PUNTA GORDA, FL 33951-2116

CRAIG D. STANLEY GULF COAST REC 5007 60 STREET EAST BRADENTON, FL 34203-9324

D. L. WRIGHT NORTH FLORIDA REC 30 RESEARCH ROAD QUINCY, FL 32351

Honorary Life Members

WILLIAM G. BLUE 1501 NW 31 ST. GAINESVILLE, FL 32605

CARROLL M. GERALDSON GULF COAST REC 5007 60 ST. EAST BRADENTON, FL 34203-9324

AMEGDA OVERMAN GULF COAST REC 5007 60 STREET E BRADENTON, FL 34203-9324

DAVID V. CALVERT INDIAN RIVER REC 1007 GRANDVIEW BLVD FT. PIERCE, FL 34982

LUTHER HAMMOND 1018 SW 25th PLACE GAINESVILLE, FL 32601

PAUL L. PFAHLER UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

VICTOR W. CARLISLE UNIVERSITY OF FLORIDA P.O. BOX 110290 GAINESVILLE, FL 32611-0290

ELVER M. HODGES 1510 HIGHWAY 64 WEST WAUCHULA, FL 33873

GORDON M. PRINE UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

R. P. ESSER P.O. BOX 147100 GAINESVILLE, FL 32614-7100

EARL S. HORNER UNIVERSITY OF FLORIDA P.O. BOX 110500 GAINESVILLE, FL 32611-0500

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DONALD L. MYHRE 2280 NW 21st PLACE GAINESVILLE, FL 32605


78

Emeritus Member

WALTER T. SCUDDER 4001 SOUTH SANFORD AVE. SANFORD, FL 32773-6007

Subscribing Members 2005

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80

Historical Record of Society Officers

Year President President Elect Secretary-Treasurer Board Directors† 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 1976 1975 1974 1973 1972 1971 1970 1969 1968 1967 1966 1965 1964 1963 1962 1961 1960 1959 1958 1957 1956 1955 1954 1953 1952 1951 1950 1949 1948 1947 1946 1945 1944 1943 1942 1941 1940 1939

K. J. Boote W. D. Thomas C. G. Chambliss C. D. Stanley D. W. Dickson R. N. Gallaher D. V. Calvert T. A. Kucharek K. H. Quesenberry R. S. Mansell J. W. Noling D. L. Wright E. E. Albregts G. H. Snyder G. C. Smart, Jr. R. S. Kalmbacher R. D. Barnett J. B. Sartain P. Mislevy D. F. Rothwell E. B. Whitty J. G. A. Fiskell G. M. Prine F. M. Rhoads O. C. Ruelke A. J. Overman V. W. Carlisle D. W. Jones W. L. Pritchett K Hinson H. L. Breland A. E. Kretschmer, Jr. L. C. Hammond F. T. Boyd C. E. Hutton E. M. Hodges W. K Robertson E. S. Horner C. M. Geraldson G. B. Killinger C. F. Eno V. E. Green, Jr. D. O. Spinks H. C. Harris W. G. Blue W. H. Chapman J. R. Henderson P. H. Senn G. D. Thornton D. E. McCloud R. W. Ruprecht F. H. Hull E. L. Spencer N. Gammon, Jr. I. W. Wander R. A. Carrigan W. T. Forsee, Jr. W. T. Forsee, Jr. H. A. Bestor H. A. Bestor H. Gunter W. E. Stokes G. M. Volk H. I. Mossbarger J. R. Neller F. B. Smith M. Peech R. V. Allison

M. B. Adjei K. J. Boote W. D. Thomas C. G. Chambliss C. D. Stanley D. W. Dickson R. N. Gallaher D. V. Calvert T. A. Kucharek K. H. Quesenberry R. S. Mansell J. W. Noling D. L. Wright E. E. Albregts G. H. Snyder G. C. Smart, Jr. R. S. Kalmbacher R. D. Barnett J. B. Sartain P. Mislevy D. F. Rothwell E. B. Whiny J. G. A. Fiskell G. M. Prine F. M. Rhoads O. C. Ruelke A. J. Overman V. W. Carlisle D. W. Jones W. L. Pritchett K. Hinson H. L. Breland A. E. Kretschmer, Jr. L. C. Hammond F. T. Boyd C. E. Hutton E. M. Hodges W. K Robertson E. S. Horner C. M. Geraldson G. B. Killinger C. F. Eno V. E. Green, Jr. D. O. Spinks H. C. Harris W. G. Blue W. H. Chapman J. R. Henderson P. H. Senn G. D. Thornton D. E. McCloud W. Reuther F. H. Hull E. L. Spencer N. Gammon, Jr. I. W. Wander R. A. Carrigan R. A. Carrigan L. H. Rogers L. H. Rogers H. A. Bestor H. Gunter W. E. Stokes G. M. Volk H. I. Mossbarger J. R. Neller F. B. Smith M. Peech

T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza T. A. Obreza C. D. Stanley C. D. Stanley C. D. Stanley C. G. Chambliss C. G. Chambliss C. G. Chambliss C. G. Chambliss C. G. Chambliss D. D. Baltensperger/C. G. Chambliss G. Kidder G. Kidder G. Kidder G. Kidder G. Kidder G. Kidder J. B. Sartain J. B. Sartain J. B. Sartain J. B. Sartain D. W. Jones D. W. Jones D. W. Jones D. W. Jones D. W. Jones D. F. Rothwell D. F. Rothwell J. NeSmith J. NeSmith J. NeSmith J. NeSmith J. NeSmith R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V. Allison R. V Allison R. A. Carrigan R. A. Carrigan

G. E. MacDonald M. B. Adjei W. D. Thomas (R. McSorley) P. Nkedi-Kizza R. M. Muchovej Robert Kinloch J. E. Rechcigl E. C. French III S. C. Schank/J. R. Rich E. A. Hanlon M. J. Williams L. E. Sollenberger D. A. Graetz J. M. Bennett F. M. Rhoads N. R. Usherwood G. C. Smart, Jr. R. W. Johnson J. W. Prevatt/J. B. Sartain/B. L. McNeal E. E. Albregts D. R. Hensel P. Mislevy D. V. Calvert G. M. Prine T. W. Winsberg F. M. Rhoads P. H. Everett O. C. Ruelke A. J. Overman R. L. Smith A. L. Taylor A. E. Kretschmer, Jr./G. L. Gascho H. L. Breland J. T. Russell †Board of Directors established in 1972 with 1, 2, and 3 year terms for the first three members. The year for each Director is when they rotate-off.


Honorary Lifetime Members Editors* 1953 1954 1955 1956 1957-19731973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

C. F. Eno C. F. Eno I. W. Wander Walter Reuther G. D. Thornton E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner E. S. Horner W. G. Blue V. E. Green, Jr. V. E. Green, Jr. V. E. Green/E. S. Horner W. G. Blue W. G. Blue W. G. Blue W. G. Blue P. L. Pfahler P. L. Pfahler P. L. Pfahler B. L. McNeal B. L. McNeal B. L. McNeal B. L. McNeal B. L. McNeal/ R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher R. S. Kalmbacher

1950 1954 1956 1959 1960 1961 1962 1963 1964 1965 1966 1970 1971 1973 1974

Selman A. Waksman Charles Franklin Kettering Sir Edward John Russell Merritt Finley Miller Frederick James Alway Sergei Nikolaevitch Winogradsky Walter Pearson Kelley Oswald Schreiner David Jacobus Hissink Charles Ernest Millar John Gordon DuPuis, M.D. Lyman James Briggs Hardrada Harold Hume Firmin Edward Bear Wilson Popenoe Pettis Holmes Senn Knowles A. Ryerson James A. McMurtrey, Jr. Herbert Kendall Hayes Harold Gray Clayton Thomas Ray Stanton Gotthold Steiner Emil Truog John William Turrentine George Dewey Scarseth Joseph R. Neller Howard E. Middleton Frank L. Holland Herman Gunter Frank E. Boyd Henry Agard Wallace Robert Verrill Allison Richard Bradfield William A. Carver William Gordon Kirk Frederick Buren Smith Marvin U. Mounts William Thomas Forsee, Jr. R. A. Carrigan Henry Clayton Harris Michael Peech Joseph Russell Henderson Ernest Leavitt Spencer Jesse Roy Christie Willard M. Fifield Joseph Riley Beckenbach

1975 1978 1979 1980 1981 1982 1984 1986 1988 1989 1990 1991 1992 1993 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

J. Cooper Morecock, Jr. George Daniel Thornton Gaylord M. Volk Gordon Beverly Killinger Roy Albert Bair Frederick Tilghman Boyd Darell Edison McCloud Nathan Gammon, Jr. Ralph Wyman Kidder Lester T. Kurtz David Wilson Jones Paul Harrison Everett Elver Myron Hodges John G. A. Fiskell Otto Charles Ruelke Victor E. Green, Jr. William Guard Blue Earl Stewart Horner Victor Walter Carlisle Donald-L. Myhre Carroll M. Geraldson Donald F. Rothwell Luther C. Hammond Amegda J. Overman Charles F. Eno Albert E. Kretschmer. Jr. Robert P. Esser Gordon M. Prine None elected None elected Paul Pfahler None elected Fred Rhoads David Calvert Grover Smart, Jr.

*Prior to 1953, the minutes printed in the Proceedings do not name the Editor, although a publication report is printed and an Editor is mentioned. The minutes imply, but do not explicitly state, that for the first several years there was an Editorial Committee with the Chairman of the Committee serving as Editor.

The Soil Science Society of Florida was formed on 18 April 1939 under the leadership of Drs. R. V. Allison, R. A. Carrigan, F. B. Smith, Michael Peech, and Mr. W. L.Tait. In 1955 the name was changed to the Soil and Crop Science Society of Florida. The Society was incorporated as a non profit organization of 6 June 1975. Thearticles of incorporation were published in Volume 35 of the Proceedings, and the By-Laws in Volume 41.

Volumes 31 and 44 of the Proceedings listed the previous officers of the Society. The information listed above draws heavily upon those two volumes and the minutes ofthe Society published in each volume. I discovered a few errors, especially in the Board of Directors, and all have beencorrected to the best of my knowledge.

Grover C. Smart, Jr., President, SCSSF, 1991-92.


82

Dedication of Proceedings Year Volume Person Year Volume Person 1939 1940 1941 1942 1942 1943 1943 1944 1945 1946-47 1948-49 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971-72 1973

1 2 3 4-A 4-B 5-A 5-B 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Robert M. Barnette H. H. Bennett & Selman A. Waksman Harry R. Leach Spessard L. Holland H. Harold Hume Nathan Mayo Wilmon Newell Herman Gunter Lewis Ralph Jones Millard F. Caldweld Willis E. Teal, Col. USA The First 11 Honorary Lifetime Members Charles R. Short Robert M. Salter J. Hillis Miller Lyman James Briggs Lorenzo A. Richards T. L. Collins & Fla. Water Resource Study Commission Firmin E. Bear Harold Mowry Work & Workers in the Fla. Agr. Ext. Serv. 1939-59 Roger W. Bledsoe Doyle Conner R. V. Allison J. G. Tigert J. R. Neller Active Charter Members of the SCSSF Fred Harold Hull Frederick Buren Smith William Thomas Forsee, Jr. Henry Clayton Harris William G. Kirk Alvin Thomas Wallace Curtis E. Hutton

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

E. Travis York, Jr. George Daniel Thornton Marshall O. Watkins Frederick T. Boyd Gaylord M. Volk Gordon Beverly Killinger Nathan Gammon, Jr. Fred Clark John W. Sites William K. Robertson Charles F. Eno Theodore (Ted) W. Winsberg Gerald O. Mott J. G. A. Fiskell Francis Aloysius Wood Victor E. Green, Jr. Earl S. Horner Amegda J. Overman William Guard Blue Charles E. Dean Luther C. Hammond Allan J. Norden Knell Hinson Noble R. Usherwood Earl E. Albregts James M. Davidson William Pritchett E. C. French A. Smajstrla S. F. Shih Shirlie West Fred M. Rhoads Grover Smart George Snyder

*In the earlier years, the Proceedings bear a date which coincides with the year of the annual meeting. During the years of World War II, publication was irregular and at least some of the volumes were published after the war. Also, the actual year that a publication is available becomes the "legal" date of a issue, not the year the meeting was held. Thus, volumes 32 and after bear a date one year after the annual meetings.

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