Organic Transplant Production: An Evaluation of Nitrogen Fertility Programs
M.C. Vann, L.R. Fisher, & R.W. SeagrovesDepartment of Crop and Soil Sciences
North Carolina State University
M.S. McGinnisNorth Carolina Department of Agriculture & Consumer Services-Agronomic Division
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Presentation Outline
• Organic Seedling Production
• Production Concerns
• Methods & Materials
• Results & Discussion
• Conclusions
• Questions
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Organic Seedling Production
• Production occurs in a float system– Nutrients are added directly to the water– OMRI listed soilless media sources
• Common Nutrient Sources:– Allganic Sodium Nitrate (16-0-0 or 15-0-2)– Peruvian Seabird Guano (12-11-2)– Bat Guano– Allganic Potassium Sulfate (0-0-52)– Acetic acid for bicarbonate adjustments– Micronutrient sources vary depending upon need
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Organic Seedling Production Concerns
• Variable N composition of nutrient sources– Sodium Nitrate: 0% Urea, 0% NH4+, 100% NO3-
– Seabird Guano: 69% Urea, 30% NH4+, 0.65% NO3-
– 16-5-16: 0% Urea, 37.5% NH4+, 62.5% NO3-
• Variable rate of N mineralization– Aerobic vs. Anaerobic conditions
• (field vs. float bed)
• Difficult to dissolve guano in solution
• High bicarbonate concentration– ≥2.0 meq HCO3-/L (>200 mg/L) can stunt
seedlings (2,4)
• High P concentration– “leggy”/“spindly” seedling characteristics (3)
• High Na concentration–
Objectives1. Identify organic fertilizer programs best suited for seedling
production
2. Identify concerns associated with those programs
3. Further develop Extension recommendations
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Methods & MaterialsTreatment List
1. Guano
2. Guano + Gypsum
3. Sodium Nitrate
4. Sodium Nitrate + Gypsum
5. Guano + Sodium Nitrate
6. Guano + Sodium Nitrate + Gypsum
7. 16-5-16 (conventional control)
Experimental Design• Central Crops Research Station
– June-July 2016– November 2016-January 2017
• RCBD, 3 replications per evaluation• 6 trays per bed
– 100 designated cells/tray for data collection– 12.7 cm float water depth– Fertilizer added 9 and 21 DAS
• Variety: K326 (Rickard Seed Co.)• Media: Carolina Choice All Natural Mix• Data analyzed using PROC Mixed in SAS
ver. 9.4• Figures created using Sigma Plot ver. 12
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Table 1. Organic fertilizer programs evaluated and the respective targeted nutritional content.
Fertilizer Programa,b,c Total N P2O5 K2O Ca__________________________________________________mg L-1__________________________________________________
Guano 125 115 20 (SG) + 105 (0-0-52) --
Guano + Gypsum 125 115 20 (SG) + 105 (0-0-52) 50
Sodium Nitrate 125 0 125 (0-0-52) --
Sodium Nitrate + Gypsum 125 0 125 (0-0-52) 50
Guano + Sodium Nitrate 44 (SG) + 81 (SN) 40 7 (SG) + 118 (0-0-52) --
Guano + Sodium Nitrate + Gypsum 44 (SG) + 81 (SN) 40 7 (SG) + 118 (0-0-52) 50
16-5-16 125 40 125 --a Guano (SG), Sunleaves 12-11-2 Peruvian Seabird Guano; Sodium Nitrate (SN), SQM Allganic 16-0-0; 16-5-16, SQM Ultrasol Premium; 0-0-52, SQM Allganic Potassium Sulfateb Fertilizer program applied twice per season, 9 and 21 days after seedingc Nutrient content calculated based upon manufacturers reported analysis
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Data Collection
• Dissolved Oxygen:– YSI DO Meter – 5 day intervals prior to solution
collection and water addition
• Solution Samples:– Source Water– 5 day intervals– 474 mL solution volume– After beds filled to 12.7 cm depth– Samples analyzed by NCDA&CS
• Media Samples:– 20 DAS and at conclusion of study– 10 cells/tray/treatment
• N=60/treatment/replication– Samples analyzed by NCDA&CS
• Seedling Measurements:– Total plants, usable plants, stem
height, & stem diameter– Conclusion of study– 10 cells/tray/treatment
• N=60/treatment/replication
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Table 2. Nutrient concentration, pH, and bicarbonate concentration of source water and soilless media prior to seedinga. Measurements are expressed in mg L-1 unless otherwise noted.
Nutrient Environment One Environment TwoSolution Media Solution Media
Total Nmin 3.96 9.03 4.12 45.68
NH4+-N 0.55 3.30 0.51 1.20
NO3--N 3.41 5.73 3.61 44.50
Urea-N 0.54 0.25 0.16 0.00
P 0.09 0.13 0.09 0.10
K 1.92 23.35 2.11 74.73
Ca 3.50 60.93 4.11 88.98
pH 6.12 4.52 6.21 4.37
HCO3- (meq L-1) 0.30 -- 0.38 --a Soilless media and source water solution samples analyzed by the North Carolina Department of Agriculture and Consumer Services-Agronomic Division, Raleigh, NC
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5 10 15 20 25 30 35 40 45
DO
Con
cent
ratio
n (m
g D
O L
-1)
0
1
2
3
4
5
6
7Guano Guano + Gypsum Sodium Nitrate Sodium Nitrate + Gypsum Guano + Sodium Nitrate Guano + Sodium Nitrate + Gypsum 16-5-16
5 10 15 20 25 30 35 40 45 50 55 60 650
1
2
3
4
5
6
7
Days After Seeding
Environment One Environment Two
Figure 1. Dissolved oxygen (DO) concentration in float water solution as influenced by seedling fertility program. Data are presented for each growing environment.
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5 10 15 20 25 30 35 40 45 50 55 60 650
25
50
75
100
125
150
175
200
225
250GuanoGuano + GypsumSodium NitrateSodium Nitrate + GypsumGuano + Sodium NitrateGuano + Sodium Nitrate + Gypsum16-5-16
5 10 15 20 25 30 35 40 45
Am
mon
ium
-N C
once
ntra
tion
(mg
NH
4+ L
-1)
0
25
50
75
100
125
150
175
200
225
250
Days After Seeding
Environment One Environment Two
Figure 2. Ammonium-nitrogen concentration in float water solution as influenced by seedling fertility program. Data are presented for each growing environment.
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5 10 15 20 25 30 35 40 45
Nitr
ate-
N C
once
ntra
tion
(NO
3- L
-1)
0
25
50
75
100
125
150
175
200
225
250 GuanoGuano + GypsumSodium NitrateSodium Nitrate + GypsumGuano + Sodium NitrateGuano + Sodium Nitrate + Gypsum16-5-16
5 10 15 20 25 30 35 40 45 50 55 60 650
25
50
75
100
125
150
175
200
225
250
Days After Seeding
Environment One Environment Two
Figure 3. Nitrate-nitrogen concentration in float water solution as influenced by seedling fertility program. Data are presented for each growing environment.
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5 10 15 20 25 30 35 40 45
pH
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
GuanoGuano + GypsumSodium NitrateSodium Nitrate + GypsumGuano + Sodium NitrateGuano + Sodium Nitrate + Gypsum16-5-16
Days After Seeding
Environment One Environment Two
Figure 4. Float water solution pH as influenced by seedling fertility program. Data are presented for each growing environment.
5 10 15 20 25 30 35 40 45 50 55 60 654.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
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5 10 15 20 25 30 35 40 45
Bica
rbon
ate C
once
ntra
tion
(meq
HC
O3-
L-1
)
0
2
4
6
8
10
12
14
16GuanoGuano + GypsumSodium NitrateSodium Nitrate + GypsumGuano + Sodium Nitrate Guano + Sodium Nitrate + Gypsum16-5-16
5 10 15 20 25 30 35 40 45 50 55 60 650
2
4
6
8
10
12
14
16
Days After Seeding
Environment One Environment Two
Figure 5. Bicarbonate concentration in float water solution as influenced by seedling fertility program. Data are presented for each growing environment. Dashed line represents 2.0 meqthreshold.
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5 10 15 20 25 30 35 40 45
NH
4+ o
r NO
3- C
once
ntra
tion
(mg
L-1 )
0
50
100
150
200
250
pH
6.0
6.5
7.0
7.5
8.0NH4
+-NNO3
--NpH
Days After Seeding
Figure 6. Ammonium, nitrate, and float water pH as influenced by guano application. Data are presented for each growing environment.
5 10 15 20 25 30 35 40 45 50 55 60 65N
H4+
or N
O3-
Con
cent
ratio
n (m
g L-
1 )
0
50
100
150
200
250
pH
6.0
6.5
7.0
7.5
8.0
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Additional Solution Observations• Urea-N concentration:
– Guano > Guano + Sodium Nitrate > Sodium Nitrate ≥ 16-5-16– Maximum of 20-25 mg/L, decreased over time
• P concentration:– Guano > 16-5-16 > Guano + Sodium Nitrate > Sodium Nitrate– Maximum of 40-50 mg/L in Guano only treatment– Guano + Sodium Nitrate > Guano > 16-5-16– >350 mg/L observed in Sodium Nitrate only treatment– High Na did not impact seedling growth, Coggins (4) did not observe injury at 580 mg/L
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Soilless Media Nutrition• Similar trends to nutrient concentration in float water solution
– Guano based treatments had highest NH4+ concentration– High NO3- concentration where sodium nitrate was exclusive N source– NO3- concentration increased from the 20 DAS sampling to the conclusion of the study
• NH4+ concentration decreased – Low P (
Table 3. Total transplants, usable transplants, transplant height, and transplant diameter reported by corresponding treatment as affected by fertility programsa,b.
Treatment Listc Total Plants Usable Plants Stem Diameter Stem Height
---------------%--------------- mm plant-1 cm plant-1
Guano 90 a 78 c 2.76 b 5.62 b
Guano + Gypsum 91 a 79 bc 2.84 b 6.08 ab
Sodium Nitrate -- -- -- --
Sodium Nitrate + Gypsum -- -- -- --
Guano + Sodium Nitrate 91 a 85 ab 3.48 a 6.27 ab
Guano + Sodium Nitrate + Gypsum 93 a 86 a 3.43 a 6.47 ab
16-5-16 88 a 79 bc 3.30 a 6.62 aaTreatment means followed by the same letter within the same column are not significant at the α=0.05 level. Data are pooled across two environments.bTreatments comprised of Sodium Nitrate only removed from analysisc Guano, Sunleaves 12-11-2 Peruvian Seabird Guano; Sodium Nitrate, SQM Allganic 16-0-0; 16-5-16, SQM Ultrasol Premium
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16-5-16
SG + 0-0-52
16-0-0 + 0-0-52
SG + 16-0-0 + 0-0-52
16-0-0 + 0-0-52 + Gypsum SG+ 0-0-52 + Gypsum
SG + 16-0-0 + 0-0-52 + GypsumSG, Seabird Guano16-0-0, Sodium Nitrate
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Guano + 16-0-0 + 0-0-52
16-5-16 Guano + 0-0-52 + Gypsum
Guano + 0-0-52
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Conclusions• 5 of 7 treatments produced acceptable transplants
– Treatments absent of P did not produce usable transplants (Sodium Nitrate only)– Supplemental P is required, not enough in source water or media
• Organic “blend” treatment was best treatment.– Guano + Sodium Nitrate + 0-0-52 (+ Gypsum)– Produced highest number of usable transplants– Balanced ammonium:nitrate ratio (1:2 or 1:3)– HCO3- concentration is more favorable for seedling growth
• Identified Guano as a source of HCO3-– Delayed/split fertilizer application may reduce HCO3- stunting– Low media pH buffers against significant pH increase from HCO3-
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Grower Recommendations
Fertilizer Programs• Program One:• Seabird Guano (13.9 oz./100 gal)
– 104 g 12-11-2/100 L H2O• 0-0-52 (2.7-3.2 oz./100 gal)
– 20-24 g/100 L H2O
• Program Two: • Seabird Guano (4.9 oz/100 gal)
– 37 g 12-11-2/100 L H2O• Sodium Nitrate (6.8 oz/100 gal)
– 51 g 16-0-0/100 L H2O• 0-0-52 (3.0 oz/100 gal)
– 20-24 g/100 L H2O
Considerations• Reduce guano particle size
• Soak guano in hot water for 24 hours
• Fertilize in split applications– 9 and 21 DAS
• Target 125 mg N/L
• Target 40 mg P/L
• Target 125 mg K/L
• Apply Ca, Mg, S, and B as needed
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References1. USDA-NASS. 2016. Certified Organic Survey-2015 Summary. Accessed September 25, 2017.
http://usda.mannlib.cornell.edu/usda/nass/OrganicProduction//2010s/2016/OrganicProduction-09-15-2016.pdf
2. NCDA&CS. 2013. Solution Analysis for Tobacco Transplant Float Beds. Accessed September 25, 2017. http://www.ncagr.gov/agronomi/pdffiles/floatbed.pdf
3. Fisher, LR and MC Vann. 2017. Producing Healthy Transplants in a Float System. In: LR Fisher, editor, 2017 North Carolina State University Flue-Cured Tobacco Production Guide (AG-187 (Revised)). Raleigh, NC: North Carolina Cooperative Extension Service. p. 44-57.
4. Coggins, TE. 1993. Effect of Sodium and Bicarbonate on Tobacco Seedling Production in the Greenhouse Float System [thesis]. Raleigh, NC: North Carolina State University. p. 129.
5. Pearce, RC, Y Zhan, and MS Coyne. 1998. Nitrogen Transformations in the Tobacco Float System. Tobacco Science 42(4):82-88.
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Acknowledgements• Technical Assistance
– Rick Seagroves– Scott Whitley– Hunter Mason– Michelle McGinnis– NCDA&CS
• Material Donation– SQM– Carolina Soil Company– Rickard Seed Company
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Questions??
Matthew C. Vann: [email protected]
Website: tobacco.ces.ncsu.eduNorth Carolina Tobacco Information
@NCSUtobacco@ncsu_tobacco
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