Research ArticleResponse of Sorghum (Sorghum bicolor L) to ResidualPhosphate in Soybean-Sorghum and Maize-Sorghum CropRotation Schemes on Two Contrasting Nigerian Alfisols
Abdulmajeed Hamza and Ezekiel Akinkunmi Akinrinde
Department of Agronomy University of Ibadan Ibadan Nigeria
Correspondence should be addressed to Abdulmajeed Hamza hamzaabdulmajeedyahoocom andEzekiel Akinkunmi Akinrinde akinakinrindeyahoocom
Received 12 February 2016 Revised 13 April 2016 Accepted 21 April 2016
Academic Editor Iskender Tiryaki
Copyright copy 2016 A Hamza and E A Akinrinde This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
The effectiveness of finely ground Sokoto Rock Phosphate and Morocco Rock Phosphate to enhance productivity of maize- (Zeamays L) Sorghum (Sorghum bicolor) and soybean- (Glycine max L) Sorghum crop rotation schemes was evaluated using SingleSuper Phosphate as reference fertilizer The experiments were carried out in the screen house of the Department of AgronomyUniversity of Ibadan in February and June 2013 The experiments involved 2 times 2 times 4 times 3 factorial in a Completely RandomizedDesign In the first and second croppings the slightly acidic loamy sand still produced higher biomass than the strongly acidicsandy clay loam On average MRP was more efficient than SSP for maize dry biomass but for soybean dry biomass MRP wasless efficient than SSP in the two soils Sokoto Rock Phosphate was less efficient in the two location soils compared to SSP for thetest crops There was no difference in performance of P-sources in the second cropping Soybean-Sorghum crop rotation schemeproduced greater Sorghum biomass than maize-Sorghum crop rotation scheme It is evident that pH and clay contents of soils aswell as the rotation crop concerned influence the efficiency of finely ground soluble phosphates in crop rotation schemes
1 Introduction
Soil acidity is a major constraint to crop production through-out the world It leads to low yields of arable crops [1] Maizeand Sorghum cannot do well with soil pH lt 55When the soilpH is around 67 it is slightly acidic but when it is less than 55it is strongly acidic [2] Crop performance could be adverselyaffected by Calcium (Ca) Potassium (K) Phosphorus (P)Magnesium (Mg) Sulphur (S) Zinc (Zn) and Molybdenum(Mo) deficiencies aswell asAlMn andFe toxicities [3]How-ever lime and fertilizer application is usually recommendedto reduce these adverse effects Phosphorus is a major plantnutrient (second only to nitrogen) Soils in Nigeria requiremoderate P-application for optimum crop growth [4] Thedirect use of sparingly soluble ground RP as substitute to thecostly more soluble P fertilizers is gaining widespread accep-tance [5] They provide slow-release P and residual effect forseveral years [6] Residual effect is the carryover effect frompreceding crops to the succeeding ones The amount and
longevity of the residual effect depends on rate duration andfrequency of application solubility soil properties crop typeyield level and extent of P removal [7]
Nitrogen (N) is another important nutrient elementneeded for crop production However in order to ensure sus-tainability organic sources of N are preferred Intercroppingor rotation of legumes with cereals is one of the ways ofreplenishing the soil with organic N among others Accord-ing to Pedersen and Lauer [8] planting of soybean in rotationwith cereals consistently gave higher yields than monocul-ture Soybean (Glycine max L) belongs to the legume familyand is an important source of organic N fertilizer [9] becauseit fixes atmospheric nitrogen in the soil [10] AtmosphericN fixation is a cheap clean renewable and environmentallyfriendly source of nitrogen (N) for the non-N-fixing cropcomponent of the cropping system [11]
The unavailability and high costs of lime and inorganic Pfertilizers have led to research into low costmaterials like rockphosphates using SSP as referenceThis study was to evaluate
Hindawi Publishing CorporationInternational Journal of AgronomyVolume 2016 Article ID 6945024 9 pageshttpdxdoiorg10115520166945024
2 International Journal of Agronomy
the effects of different P-sources Single Supper Phosphate(SSP) Sokoto Rock Phosphate (SRP) and Morocco RockPhosphate (MRP) on the performance of maize and soybeanin two soil types with the residual effects of the P-sources andthe preceding crop on the performance of Sorghum in twocrop rotation schemes
2 Materials and Methods
21 Experimental Site There were two experiments con-ducted between February and June 2013 in the screen houseDepartment ofAgronomyFacultyofAgriculture andForestryUniversity of Ibadan Nigeria The greenhouse conditionswere suitable for plants growth where the wall and the doorof the greenhouse were made up of metals with wire nets androofed with transparent glasses The floor was well cementedand there were metals tables inside on which the pots werekept The planting date for Experiment 1 was February 232013 and that of Experiment 2 was May 25 2013 Theuniversity is located at latitude 7∘241015840N and longitude 3∘541015840E
22 Experimental Design and Treatments The experimentsinvolved 2 (maize and soybean) times 2 (two soil types) times 4 (fourlevels of Phosphorus) times 3 replications (total of 48 treatments)in a Completely Randomized Design (CRD)
Experiment 1 (effect of different phosphorus fertilizer sourceson the performance ofmaize and soybean grown on two con-trastingNigerianAlfisols) In the first experiment treatmentswere as follows
(i) Phosphorus Fertilizer Absolute Control (0P2O5) Sokoto
Rock Phosphate (342 P2O5by weight) Morocco Rock
Phosphate (333 P2O5by weight) and Single Super Phos-
phate (18 P2O5) the three Phosphorus fertilizers were col-
lected fromDepartment of Agronomy Faculty of Agricultureand Forestry University of Ibadan Nigeria
(ii) Soil Locations The two soils were collected from differentlocations The sandy clay loam soil was strong acidic Alfisolcollected from Leventis Foundation School of AgricultureImoo Ilesa Osun State This area lies within the rainforestvegetation zone of Nigeria According to Oyedele et al [12]the parent rocks consist essentially of quartz with smallamounts of white micaceous minerals Also in this areadensely wooded quartz ridges rise abruptly from the sur-rounding country and are elongated north south followingthe strike of the rock Akintoye et al [13] stated that the soilsround Ilesa are classified as Alfisols (mainly Paleustalf) Thesoil in this area belongs to the Okemesi series [12 14] whilethe loamy sand soil was very slightly acidic Alfisol collectedfromParryRoadDepartment ofAgronomyFarmUniversityof Ibadan Ibadan Oyo State According to USDA [15] thesoils around Ibadan are classified as Alfisols (Typic Plinthus-talf) The soil in this area belongs to the Gambari series
(iii) Test Crops Maize (Zea mays var Swan-1) was collectedfrom Department of Agronomy College of Agriculture andForestry University of Ibadan Nigeria and soybean (Glycine
max var TGX 1448-2E) was gotten from International Insti-tute of Tropical Agriculture (IITA) IbadanOyo State for firstcropping
23 Methodology The two soils were crushed with mortarand pestle and passed through a 2mm sieve separately Thechemical and physical properties of the two soils were deter-mined in the laboratory according to Udo andOgunwale [16]methods For each of the soil locations 4 kg was weighedusing weighing balance into 24 bows and made a total of 48bows of the two soils 100mg P
2O5kg soil of finely ground
Sokoto Rock Phosphate SRP (342 P2O5) Morocco Rock
Phosphate MRP (333 P2O5) Single Super Phosphate SSP
(18 P2O5) and Control (0 P
2O5) was thoroughly mixed
with the soil in each bowThe soil in each bow was later filledinto forty-eight 4 kg of pots
24 Water Field Capacity Water field capacities of the twosoils were determined in the laboratory 50 g of each soil wasweighed using sensitive scale Two funnels were placed ontwo cylindrical flacks Small tissue papers were put insidethe funnels based to prevent soils pour-off The 50 g of thetwo soils was separately put into each funnel placed on thecylindrical flasks 50mL each of water was poured on thetwo soils in the funnels They were allowed to drain into thecylindrical flasks until they stopped droppingThe volumes ofdrained water in each cylindrical flask were subtracted fromthe actual volume of water poured The water field capacityof the strongly acidic sandy clay loam was 2500mL whilethe field capacity of slightly acidic loamy sand was 1500mLThe two soils inside the 4 kg pots containing each phosphatefertilizer andControl were watered to 60 field capacity (FC)and allowed to equilibrate for 3 days
25 Planting of Test Crops Maize (Zea mays var Swan-1) andsoybean (Glycine max var TGX1448-2E) were planted as thefirst crops Three seeds of maize (Zea mays) and soybean(Glycine max) were planted per pot and two seedlings of thetest crops were allowed to grow in each pot for 6 weeks
26 Data Collected on Maize (Zea mays L) and Soybean(Glycine max) Data on the following were taken weeklystarting from first week after planting
(i) Heights (cm) plant heights were measured from thesoil level to terminal bud using a measuring tape forsix weeks
(ii) Dry biomass yield (gkg) after harvest the freshbiomass yields were thoroughly washed with waterand air-dried They were later oven-dried at 75∘C for24 hours to constant weight and the dry biomassyields were weighed using a sensitive scale
Experiment 2 (residual effect of phosphorus- (P-) sources ondry biomass yield of Sorghum productions on two contrastingNigerian Alfisols) In order to determine the response of Sor-ghum (Sorghum bicolor L var Sokoto local) to residual effectsof the P-sources (SRP MRP SSP and Control) in the two
International Journal of Agronomy 3
Table 1 Precropping chemical and particle size analysis of the soils used in the study
Properties Soil A (strongly acidic Alfisol) Soil B (slightly acidic Alfisol)pH (1 1 soilwater ratio) 53 67Bray-1-P (mgkg) 5 9Total N (gkg) 20 20Organic matter (gkg) 271 265Exchangeable base (cmolkg)
Particle size distribution (gkgminus1)Sand 6280 8710Silt 1500 400Clay 2220 890
Texture Sandy clay loam Loamy sand
soils the biomass yield of Sorghum (Sorghum bicolor L varSokoto local) was also evaluated after air-drying and sievingof the first experimental soils and 50 seeds of Sorghum weresown inside each pot that is maize-Sorghum and soybean-Sorghum crop rotation schemesThe Sorghum plants were cutat 2 WAP and allowed to regenerate before they were cut inanother 2 weeks
27 Data Collected on White Sorghum (Sorghum bicolor L)Fresh biomass yields of Sorghum plants were cut 2 cm abovethe soils surfaces every two weeks of growth After harvestthe fresh biomass yields were thoroughly washed with waterand air-driedThey were later oven-dried at 75∘C for 24 hoursto constant weight and the dry biomass yields were weighedusing a sensitive scale
28 Statistical Analysis The data collected were subjectedto Analysis of Variance (ANOVA) to determine the level ofsignificance of the treatments using SAS (Statistical AnalysisSystem) 2002 computer software (version 90) Treatmenteffects and magnitude of interactions were determined LSDwas used to detect differences between treatmentmeans at 5significant level
29 Relative Agronomic Efficiency (RAE) The vertical com-parison approach was used in this study to measure therelative agronomic efficiency (RAE) index of the Sokoto RockPhosphate (SRP) and Morocco Rock Phosphate (MRP) Thisapproach defines the RAE index as the ratio of the yieldresponse above Control with the test fertilizer at the same rate[17]
Mathematically
RAE
=
Yield of Rock Phosphate minus Yield of ControlYield of Single Super Phosphate minus Yield of Control
times 100
(1)
3 Results
31 Experiment 1
311 Precropping Soil Characteristics The particle size anal-ysis and the chemical properties of the two soils used inthis study are given in Table 1 The Ilesa location soil (SoilA) was strongly acidic sandy clay loams (pH 53) while theIbadan location soil (Soil B) was slightly acidic loamy sand(pH 67) Available P in the strongly acidic sandy clay loamwas lower (5mgkg) in slightly acidic loamy sand (9mgkg)The two soils had adequate amount of total nitrogen (2 gkg)Organic matter content of the strongly acidic sandy clay loam(271 gkg) was slightly higher than the slightly acidic loamysand (265 gkg) Exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) compared to that ofslightly acidic loamy sand (003 cmolkg)
There was no significant difference (119901 lt 005) betweenthe heights of maize plants grown on strongly acidic sandyclay loam and those grown on slightly acidic loamy sanduntil 4 weeks after planting (WAP) However soybean plantsgrown on the two soils exhibited no significant difference(119901 lt 005) throughout the growing period Nevertheless the
4 International Journal of Agronomy
Table 2 Influence of soils on heights (cm) of maize and soybeanplants (at successive growth periods) in the first cropping
slightly acidic loamy sand tends to produce taller plantscompared to the strongly acidic sandy clay loam (Table 2)
The heights of plants treated with different Phosphorustreatments (sources) were significant (119901 lt 005) differentonly at 5 WAP for maize whereas for soybean significantdifferences were evident at both 5 and 6 WAP The order ofthe magnitude of the performance of the P-sources was SSPgtMRP gt SRP gt Control (Table 3)
There was no significant (119901 lt 005) difference betweenthe dry biomass yields of maize plants treated with SSP andMRP as well as SRP and Control However the dry biomassyield of maize plants treated with SSP or MRP was signif-icantly different from those treated with SRP or Control(Table 4) The same trend was observed on dry biomass yieldin plant tissue of soybean plants as those of the biomass yieldof maize plantsThe order of the effectiveness of P-sources ondry biomass yield of maize plants was MRP gt SSP gt SRP gtControl while that of soybean was SSP gt MRP gt SRP gtControl
Table 4 Influence of P-sources on biomass yield (gpot) and relativeagronomic efficiency (RAE) () of maizesoybean plants in the firstcropping
Treatment Dry biomass (gpot) RAE ()Phosphate fertilizers Maize plantControl 1167Morocco Rock 1843 11438Sokoto Rock 1265 1658Single super 1758 100LSD (5) 239
Soybean plantControl 824Morocco Rock 1142 8503Sokoto Rock 456 NDSingle super 1198 100LSD (5) 249
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
Table 5 Influence of soils and P-sources on dry biomass yield(gpot) and relative agronomic efficiency (RAE) () of maizesoy-bean plants in the first cropping
Treatment Dry biomass (gpot) RAE ()Maize plant
Strongly acidic
Control 420Morocco RP 1240 8817Sokoto RP 857 4699Single SP 1350 100
Slightly acidic
Control 1913Morocco RP 2447 21024Sokoto RP 1673 NDSingle SP 2167 100
LSD (5) 338Soybean plant
Strongly acidic
Control 465Morocco RP 957 13977Sokoto RP 402 NDSingle SP 817 100
Slightly acidic
Control 1183Morocco RP 1326 362Sokoto RP 511 NDSingle SP 1578 100
LSD (5) 353RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005ND = not determined
There was significant (119901 lt 005) difference between drybiomass yields of maize plants cut on slightly acidic soilstreated with either SSP or MRP and those treated with SRPor strongly acidic soils treated with P-sources (Table 5) The
International Journal of Agronomy 5
Table 6 Influence of the soils P-source or crop effects on biomass yield (gpot) of Sorghum plants in the second cropping
Phosphate fertilizersControl 21 012Morocco Rock 2 ND 011 50Sokoto Rock 192 ND 013 NDSingle super 207 100 01 100LSD (5) NS NS
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]RY = relative yield of test crop (maize or soybean) = [(yield of the crop on a particular soil typemaximum yield) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
order of the effectiveness of the soils and P-sources on drybiomass yield of maize plants cut on strongly acidic soil wasSSP gt MRP gt SSP gt Control while on slightly acidic soil itwas MRP gt SSP gt Control gt SRP However there was no sig-nificant (119901 lt 005) difference between dry biomass yields ofsoybean plants cut on slightly acidic soil treated with SSPand those treated with MRP whereas there were significantdifferences from those treated with SRP as well as those cuton strongly acidic soil The order of the effectiveness of thesoils and P-sources on dry biomass yield of soybean plantswas SSP gtMRP gt Control gt SRP on slightly acidic soil whileon strongly acidic soil it was MRP gt SSP gt SRP gt Control(Table 5)
Sokoto Rock Phosphate was less than 50 efficient inthe two location soils compared to SSP for the test cropsThe MRP (relative agronomic efficiency RAE of 21024)was more efficient than SSP (100 RAE) in slightly acidicloamy sand but less efficient in strongly acidic sandy clayloam (8817 RAE) compared to SSP (100 RAE) for maize(Table 5) However for soybean (Glycine max L) MRP(362 RAE) was less efficient than SSP (100 RAE) inslightly acidic loamy sand butmore efficient (13977RAE) instrongly acidic sandy clay loam compared to SSP (100RAE)(Table 5)
32 Experiment 2 It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam (Table 6) The soybean-Sorghum crop rotational scheme constantly produced drybiomass yield of Sorghum plants compared to that of maize-Sorghum crop rotational scheme (Table 6) Based on theresidual effects of the various P fertilizer treatments the drybiomass yields of Sorghum plants at first and second cuttingswere not different (Table 6)
For the residual influence of the soils and P-sources therewere no significant differences (119901 lt 005) among the Sorghumdry biomass yield produced on the two soils treated withthe various P-sources and untreated ones at the first andsecond cuttings However similar trend was observed on theinfluence of the crop effects and soils on Sorghum dry biomassyield as those produced on soils and P-sources (Table 7)
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However inslightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants
The relative yields of dry biomass yield of Sorghum insoybean-Sorghum crop effect are greater than those of maize-Sorghum crop effect at both first and second cuttings
The various residual effects of crop effects and P-sourceson dry biomass yield of Sorghum plants were significant(119901 lt 005) at first cutting The highest dry biomass yield ofSorghum plants was gotten from the influence of soybean-Sorghum treated with SSP while the least result was gottenfrom the influence of maize-Sorghum treated with SSP atthe first cutting At the second cutting the influence of cropeffects and P-sources had no significant difference on drybiomass yield of Sorghum plants However inmaize-Sorghumonly MRP was 7813 as efficient as SSP at first cutting ofSorghum plants (Table 8)
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)show that there were no significant differences The implica-tion is that plant vigour and biomass yields did not differ atthe various levels of each of the experimental factors
6 International Journal of Agronomy
Table 7 Influence of the experimental soils and P-source or crop effects and soils on dry biomass yield (gpot) of Sorghum plants in thesecond cropping
TreatmentDry biomass (gpot) Dry biomass (gpot)
Mean Standard deviation RAE () Mean Standard deviation RAE ()First cutting Second cutting
Soils acidity level Phosphate fertilizer
Strongly acidic
Control 192 plusmn052 011 plusmn016Morocco Rock Phosphate 155 plusmn069 13704 007 plusmn008 NDSokoto Rock Phosphate 169 plusmn025 8519 006 plusmn009 NDSingle Super Phosphate 165 plusmn055 100 012 plusmn020 100
Slightly acidic
Control 228 plusmn037 012 plusmn018Morocco Rock Phosphate 246 plusmn081 8571 014 plusmn014 NDSokoto Rock Phosphate 215 plusmn060 ND 02 plusmn028 NDSingle Super Phosphate 249 plusmn114 100 007 plusmn009 100
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
the effects of different P-sources Single Supper Phosphate(SSP) Sokoto Rock Phosphate (SRP) and Morocco RockPhosphate (MRP) on the performance of maize and soybeanin two soil types with the residual effects of the P-sources andthe preceding crop on the performance of Sorghum in twocrop rotation schemes
2 Materials and Methods
21 Experimental Site There were two experiments con-ducted between February and June 2013 in the screen houseDepartment ofAgronomyFacultyofAgriculture andForestryUniversity of Ibadan Nigeria The greenhouse conditionswere suitable for plants growth where the wall and the doorof the greenhouse were made up of metals with wire nets androofed with transparent glasses The floor was well cementedand there were metals tables inside on which the pots werekept The planting date for Experiment 1 was February 232013 and that of Experiment 2 was May 25 2013 Theuniversity is located at latitude 7∘241015840N and longitude 3∘541015840E
22 Experimental Design and Treatments The experimentsinvolved 2 (maize and soybean) times 2 (two soil types) times 4 (fourlevels of Phosphorus) times 3 replications (total of 48 treatments)in a Completely Randomized Design (CRD)
Experiment 1 (effect of different phosphorus fertilizer sourceson the performance ofmaize and soybean grown on two con-trastingNigerianAlfisols) In the first experiment treatmentswere as follows
(i) Phosphorus Fertilizer Absolute Control (0P2O5) Sokoto
Rock Phosphate (342 P2O5by weight) Morocco Rock
Phosphate (333 P2O5by weight) and Single Super Phos-
phate (18 P2O5) the three Phosphorus fertilizers were col-
lected fromDepartment of Agronomy Faculty of Agricultureand Forestry University of Ibadan Nigeria
(ii) Soil Locations The two soils were collected from differentlocations The sandy clay loam soil was strong acidic Alfisolcollected from Leventis Foundation School of AgricultureImoo Ilesa Osun State This area lies within the rainforestvegetation zone of Nigeria According to Oyedele et al [12]the parent rocks consist essentially of quartz with smallamounts of white micaceous minerals Also in this areadensely wooded quartz ridges rise abruptly from the sur-rounding country and are elongated north south followingthe strike of the rock Akintoye et al [13] stated that the soilsround Ilesa are classified as Alfisols (mainly Paleustalf) Thesoil in this area belongs to the Okemesi series [12 14] whilethe loamy sand soil was very slightly acidic Alfisol collectedfromParryRoadDepartment ofAgronomyFarmUniversityof Ibadan Ibadan Oyo State According to USDA [15] thesoils around Ibadan are classified as Alfisols (Typic Plinthus-talf) The soil in this area belongs to the Gambari series
(iii) Test Crops Maize (Zea mays var Swan-1) was collectedfrom Department of Agronomy College of Agriculture andForestry University of Ibadan Nigeria and soybean (Glycine
max var TGX 1448-2E) was gotten from International Insti-tute of Tropical Agriculture (IITA) IbadanOyo State for firstcropping
23 Methodology The two soils were crushed with mortarand pestle and passed through a 2mm sieve separately Thechemical and physical properties of the two soils were deter-mined in the laboratory according to Udo andOgunwale [16]methods For each of the soil locations 4 kg was weighedusing weighing balance into 24 bows and made a total of 48bows of the two soils 100mg P
2O5kg soil of finely ground
Sokoto Rock Phosphate SRP (342 P2O5) Morocco Rock
Phosphate MRP (333 P2O5) Single Super Phosphate SSP
(18 P2O5) and Control (0 P
2O5) was thoroughly mixed
with the soil in each bowThe soil in each bow was later filledinto forty-eight 4 kg of pots
24 Water Field Capacity Water field capacities of the twosoils were determined in the laboratory 50 g of each soil wasweighed using sensitive scale Two funnels were placed ontwo cylindrical flacks Small tissue papers were put insidethe funnels based to prevent soils pour-off The 50 g of thetwo soils was separately put into each funnel placed on thecylindrical flasks 50mL each of water was poured on thetwo soils in the funnels They were allowed to drain into thecylindrical flasks until they stopped droppingThe volumes ofdrained water in each cylindrical flask were subtracted fromthe actual volume of water poured The water field capacityof the strongly acidic sandy clay loam was 2500mL whilethe field capacity of slightly acidic loamy sand was 1500mLThe two soils inside the 4 kg pots containing each phosphatefertilizer andControl were watered to 60 field capacity (FC)and allowed to equilibrate for 3 days
25 Planting of Test Crops Maize (Zea mays var Swan-1) andsoybean (Glycine max var TGX1448-2E) were planted as thefirst crops Three seeds of maize (Zea mays) and soybean(Glycine max) were planted per pot and two seedlings of thetest crops were allowed to grow in each pot for 6 weeks
26 Data Collected on Maize (Zea mays L) and Soybean(Glycine max) Data on the following were taken weeklystarting from first week after planting
(i) Heights (cm) plant heights were measured from thesoil level to terminal bud using a measuring tape forsix weeks
(ii) Dry biomass yield (gkg) after harvest the freshbiomass yields were thoroughly washed with waterand air-dried They were later oven-dried at 75∘C for24 hours to constant weight and the dry biomassyields were weighed using a sensitive scale
Experiment 2 (residual effect of phosphorus- (P-) sources ondry biomass yield of Sorghum productions on two contrastingNigerian Alfisols) In order to determine the response of Sor-ghum (Sorghum bicolor L var Sokoto local) to residual effectsof the P-sources (SRP MRP SSP and Control) in the two
International Journal of Agronomy 3
Table 1 Precropping chemical and particle size analysis of the soils used in the study
Properties Soil A (strongly acidic Alfisol) Soil B (slightly acidic Alfisol)pH (1 1 soilwater ratio) 53 67Bray-1-P (mgkg) 5 9Total N (gkg) 20 20Organic matter (gkg) 271 265Exchangeable base (cmolkg)
Particle size distribution (gkgminus1)Sand 6280 8710Silt 1500 400Clay 2220 890
Texture Sandy clay loam Loamy sand
soils the biomass yield of Sorghum (Sorghum bicolor L varSokoto local) was also evaluated after air-drying and sievingof the first experimental soils and 50 seeds of Sorghum weresown inside each pot that is maize-Sorghum and soybean-Sorghum crop rotation schemesThe Sorghum plants were cutat 2 WAP and allowed to regenerate before they were cut inanother 2 weeks
27 Data Collected on White Sorghum (Sorghum bicolor L)Fresh biomass yields of Sorghum plants were cut 2 cm abovethe soils surfaces every two weeks of growth After harvestthe fresh biomass yields were thoroughly washed with waterand air-driedThey were later oven-dried at 75∘C for 24 hoursto constant weight and the dry biomass yields were weighedusing a sensitive scale
28 Statistical Analysis The data collected were subjectedto Analysis of Variance (ANOVA) to determine the level ofsignificance of the treatments using SAS (Statistical AnalysisSystem) 2002 computer software (version 90) Treatmenteffects and magnitude of interactions were determined LSDwas used to detect differences between treatmentmeans at 5significant level
29 Relative Agronomic Efficiency (RAE) The vertical com-parison approach was used in this study to measure therelative agronomic efficiency (RAE) index of the Sokoto RockPhosphate (SRP) and Morocco Rock Phosphate (MRP) Thisapproach defines the RAE index as the ratio of the yieldresponse above Control with the test fertilizer at the same rate[17]
Mathematically
RAE
=
Yield of Rock Phosphate minus Yield of ControlYield of Single Super Phosphate minus Yield of Control
times 100
(1)
3 Results
31 Experiment 1
311 Precropping Soil Characteristics The particle size anal-ysis and the chemical properties of the two soils used inthis study are given in Table 1 The Ilesa location soil (SoilA) was strongly acidic sandy clay loams (pH 53) while theIbadan location soil (Soil B) was slightly acidic loamy sand(pH 67) Available P in the strongly acidic sandy clay loamwas lower (5mgkg) in slightly acidic loamy sand (9mgkg)The two soils had adequate amount of total nitrogen (2 gkg)Organic matter content of the strongly acidic sandy clay loam(271 gkg) was slightly higher than the slightly acidic loamysand (265 gkg) Exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) compared to that ofslightly acidic loamy sand (003 cmolkg)
There was no significant difference (119901 lt 005) betweenthe heights of maize plants grown on strongly acidic sandyclay loam and those grown on slightly acidic loamy sanduntil 4 weeks after planting (WAP) However soybean plantsgrown on the two soils exhibited no significant difference(119901 lt 005) throughout the growing period Nevertheless the
4 International Journal of Agronomy
Table 2 Influence of soils on heights (cm) of maize and soybeanplants (at successive growth periods) in the first cropping
slightly acidic loamy sand tends to produce taller plantscompared to the strongly acidic sandy clay loam (Table 2)
The heights of plants treated with different Phosphorustreatments (sources) were significant (119901 lt 005) differentonly at 5 WAP for maize whereas for soybean significantdifferences were evident at both 5 and 6 WAP The order ofthe magnitude of the performance of the P-sources was SSPgtMRP gt SRP gt Control (Table 3)
There was no significant (119901 lt 005) difference betweenthe dry biomass yields of maize plants treated with SSP andMRP as well as SRP and Control However the dry biomassyield of maize plants treated with SSP or MRP was signif-icantly different from those treated with SRP or Control(Table 4) The same trend was observed on dry biomass yieldin plant tissue of soybean plants as those of the biomass yieldof maize plantsThe order of the effectiveness of P-sources ondry biomass yield of maize plants was MRP gt SSP gt SRP gtControl while that of soybean was SSP gt MRP gt SRP gtControl
Table 4 Influence of P-sources on biomass yield (gpot) and relativeagronomic efficiency (RAE) () of maizesoybean plants in the firstcropping
Treatment Dry biomass (gpot) RAE ()Phosphate fertilizers Maize plantControl 1167Morocco Rock 1843 11438Sokoto Rock 1265 1658Single super 1758 100LSD (5) 239
Soybean plantControl 824Morocco Rock 1142 8503Sokoto Rock 456 NDSingle super 1198 100LSD (5) 249
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
Table 5 Influence of soils and P-sources on dry biomass yield(gpot) and relative agronomic efficiency (RAE) () of maizesoy-bean plants in the first cropping
Treatment Dry biomass (gpot) RAE ()Maize plant
Strongly acidic
Control 420Morocco RP 1240 8817Sokoto RP 857 4699Single SP 1350 100
Slightly acidic
Control 1913Morocco RP 2447 21024Sokoto RP 1673 NDSingle SP 2167 100
LSD (5) 338Soybean plant
Strongly acidic
Control 465Morocco RP 957 13977Sokoto RP 402 NDSingle SP 817 100
Slightly acidic
Control 1183Morocco RP 1326 362Sokoto RP 511 NDSingle SP 1578 100
LSD (5) 353RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005ND = not determined
There was significant (119901 lt 005) difference between drybiomass yields of maize plants cut on slightly acidic soilstreated with either SSP or MRP and those treated with SRPor strongly acidic soils treated with P-sources (Table 5) The
International Journal of Agronomy 5
Table 6 Influence of the soils P-source or crop effects on biomass yield (gpot) of Sorghum plants in the second cropping
Phosphate fertilizersControl 21 012Morocco Rock 2 ND 011 50Sokoto Rock 192 ND 013 NDSingle super 207 100 01 100LSD (5) NS NS
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]RY = relative yield of test crop (maize or soybean) = [(yield of the crop on a particular soil typemaximum yield) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
order of the effectiveness of the soils and P-sources on drybiomass yield of maize plants cut on strongly acidic soil wasSSP gt MRP gt SSP gt Control while on slightly acidic soil itwas MRP gt SSP gt Control gt SRP However there was no sig-nificant (119901 lt 005) difference between dry biomass yields ofsoybean plants cut on slightly acidic soil treated with SSPand those treated with MRP whereas there were significantdifferences from those treated with SRP as well as those cuton strongly acidic soil The order of the effectiveness of thesoils and P-sources on dry biomass yield of soybean plantswas SSP gtMRP gt Control gt SRP on slightly acidic soil whileon strongly acidic soil it was MRP gt SSP gt SRP gt Control(Table 5)
Sokoto Rock Phosphate was less than 50 efficient inthe two location soils compared to SSP for the test cropsThe MRP (relative agronomic efficiency RAE of 21024)was more efficient than SSP (100 RAE) in slightly acidicloamy sand but less efficient in strongly acidic sandy clayloam (8817 RAE) compared to SSP (100 RAE) for maize(Table 5) However for soybean (Glycine max L) MRP(362 RAE) was less efficient than SSP (100 RAE) inslightly acidic loamy sand butmore efficient (13977RAE) instrongly acidic sandy clay loam compared to SSP (100RAE)(Table 5)
32 Experiment 2 It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam (Table 6) The soybean-Sorghum crop rotational scheme constantly produced drybiomass yield of Sorghum plants compared to that of maize-Sorghum crop rotational scheme (Table 6) Based on theresidual effects of the various P fertilizer treatments the drybiomass yields of Sorghum plants at first and second cuttingswere not different (Table 6)
For the residual influence of the soils and P-sources therewere no significant differences (119901 lt 005) among the Sorghumdry biomass yield produced on the two soils treated withthe various P-sources and untreated ones at the first andsecond cuttings However similar trend was observed on theinfluence of the crop effects and soils on Sorghum dry biomassyield as those produced on soils and P-sources (Table 7)
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However inslightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants
The relative yields of dry biomass yield of Sorghum insoybean-Sorghum crop effect are greater than those of maize-Sorghum crop effect at both first and second cuttings
The various residual effects of crop effects and P-sourceson dry biomass yield of Sorghum plants were significant(119901 lt 005) at first cutting The highest dry biomass yield ofSorghum plants was gotten from the influence of soybean-Sorghum treated with SSP while the least result was gottenfrom the influence of maize-Sorghum treated with SSP atthe first cutting At the second cutting the influence of cropeffects and P-sources had no significant difference on drybiomass yield of Sorghum plants However inmaize-Sorghumonly MRP was 7813 as efficient as SSP at first cutting ofSorghum plants (Table 8)
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)show that there were no significant differences The implica-tion is that plant vigour and biomass yields did not differ atthe various levels of each of the experimental factors
6 International Journal of Agronomy
Table 7 Influence of the experimental soils and P-source or crop effects and soils on dry biomass yield (gpot) of Sorghum plants in thesecond cropping
TreatmentDry biomass (gpot) Dry biomass (gpot)
Mean Standard deviation RAE () Mean Standard deviation RAE ()First cutting Second cutting
Soils acidity level Phosphate fertilizer
Strongly acidic
Control 192 plusmn052 011 plusmn016Morocco Rock Phosphate 155 plusmn069 13704 007 plusmn008 NDSokoto Rock Phosphate 169 plusmn025 8519 006 plusmn009 NDSingle Super Phosphate 165 plusmn055 100 012 plusmn020 100
Slightly acidic
Control 228 plusmn037 012 plusmn018Morocco Rock Phosphate 246 plusmn081 8571 014 plusmn014 NDSokoto Rock Phosphate 215 plusmn060 ND 02 plusmn028 NDSingle Super Phosphate 249 plusmn114 100 007 plusmn009 100
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
Particle size distribution (gkgminus1)Sand 6280 8710Silt 1500 400Clay 2220 890
Texture Sandy clay loam Loamy sand
soils the biomass yield of Sorghum (Sorghum bicolor L varSokoto local) was also evaluated after air-drying and sievingof the first experimental soils and 50 seeds of Sorghum weresown inside each pot that is maize-Sorghum and soybean-Sorghum crop rotation schemesThe Sorghum plants were cutat 2 WAP and allowed to regenerate before they were cut inanother 2 weeks
27 Data Collected on White Sorghum (Sorghum bicolor L)Fresh biomass yields of Sorghum plants were cut 2 cm abovethe soils surfaces every two weeks of growth After harvestthe fresh biomass yields were thoroughly washed with waterand air-driedThey were later oven-dried at 75∘C for 24 hoursto constant weight and the dry biomass yields were weighedusing a sensitive scale
28 Statistical Analysis The data collected were subjectedto Analysis of Variance (ANOVA) to determine the level ofsignificance of the treatments using SAS (Statistical AnalysisSystem) 2002 computer software (version 90) Treatmenteffects and magnitude of interactions were determined LSDwas used to detect differences between treatmentmeans at 5significant level
29 Relative Agronomic Efficiency (RAE) The vertical com-parison approach was used in this study to measure therelative agronomic efficiency (RAE) index of the Sokoto RockPhosphate (SRP) and Morocco Rock Phosphate (MRP) Thisapproach defines the RAE index as the ratio of the yieldresponse above Control with the test fertilizer at the same rate[17]
Mathematically
RAE
=
Yield of Rock Phosphate minus Yield of ControlYield of Single Super Phosphate minus Yield of Control
times 100
(1)
3 Results
31 Experiment 1
311 Precropping Soil Characteristics The particle size anal-ysis and the chemical properties of the two soils used inthis study are given in Table 1 The Ilesa location soil (SoilA) was strongly acidic sandy clay loams (pH 53) while theIbadan location soil (Soil B) was slightly acidic loamy sand(pH 67) Available P in the strongly acidic sandy clay loamwas lower (5mgkg) in slightly acidic loamy sand (9mgkg)The two soils had adequate amount of total nitrogen (2 gkg)Organic matter content of the strongly acidic sandy clay loam(271 gkg) was slightly higher than the slightly acidic loamysand (265 gkg) Exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) compared to that ofslightly acidic loamy sand (003 cmolkg)
There was no significant difference (119901 lt 005) betweenthe heights of maize plants grown on strongly acidic sandyclay loam and those grown on slightly acidic loamy sanduntil 4 weeks after planting (WAP) However soybean plantsgrown on the two soils exhibited no significant difference(119901 lt 005) throughout the growing period Nevertheless the
4 International Journal of Agronomy
Table 2 Influence of soils on heights (cm) of maize and soybeanplants (at successive growth periods) in the first cropping
slightly acidic loamy sand tends to produce taller plantscompared to the strongly acidic sandy clay loam (Table 2)
The heights of plants treated with different Phosphorustreatments (sources) were significant (119901 lt 005) differentonly at 5 WAP for maize whereas for soybean significantdifferences were evident at both 5 and 6 WAP The order ofthe magnitude of the performance of the P-sources was SSPgtMRP gt SRP gt Control (Table 3)
There was no significant (119901 lt 005) difference betweenthe dry biomass yields of maize plants treated with SSP andMRP as well as SRP and Control However the dry biomassyield of maize plants treated with SSP or MRP was signif-icantly different from those treated with SRP or Control(Table 4) The same trend was observed on dry biomass yieldin plant tissue of soybean plants as those of the biomass yieldof maize plantsThe order of the effectiveness of P-sources ondry biomass yield of maize plants was MRP gt SSP gt SRP gtControl while that of soybean was SSP gt MRP gt SRP gtControl
Table 4 Influence of P-sources on biomass yield (gpot) and relativeagronomic efficiency (RAE) () of maizesoybean plants in the firstcropping
Treatment Dry biomass (gpot) RAE ()Phosphate fertilizers Maize plantControl 1167Morocco Rock 1843 11438Sokoto Rock 1265 1658Single super 1758 100LSD (5) 239
Soybean plantControl 824Morocco Rock 1142 8503Sokoto Rock 456 NDSingle super 1198 100LSD (5) 249
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
Table 5 Influence of soils and P-sources on dry biomass yield(gpot) and relative agronomic efficiency (RAE) () of maizesoy-bean plants in the first cropping
Treatment Dry biomass (gpot) RAE ()Maize plant
Strongly acidic
Control 420Morocco RP 1240 8817Sokoto RP 857 4699Single SP 1350 100
Slightly acidic
Control 1913Morocco RP 2447 21024Sokoto RP 1673 NDSingle SP 2167 100
LSD (5) 338Soybean plant
Strongly acidic
Control 465Morocco RP 957 13977Sokoto RP 402 NDSingle SP 817 100
Slightly acidic
Control 1183Morocco RP 1326 362Sokoto RP 511 NDSingle SP 1578 100
LSD (5) 353RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005ND = not determined
There was significant (119901 lt 005) difference between drybiomass yields of maize plants cut on slightly acidic soilstreated with either SSP or MRP and those treated with SRPor strongly acidic soils treated with P-sources (Table 5) The
International Journal of Agronomy 5
Table 6 Influence of the soils P-source or crop effects on biomass yield (gpot) of Sorghum plants in the second cropping
Phosphate fertilizersControl 21 012Morocco Rock 2 ND 011 50Sokoto Rock 192 ND 013 NDSingle super 207 100 01 100LSD (5) NS NS
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]RY = relative yield of test crop (maize or soybean) = [(yield of the crop on a particular soil typemaximum yield) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
order of the effectiveness of the soils and P-sources on drybiomass yield of maize plants cut on strongly acidic soil wasSSP gt MRP gt SSP gt Control while on slightly acidic soil itwas MRP gt SSP gt Control gt SRP However there was no sig-nificant (119901 lt 005) difference between dry biomass yields ofsoybean plants cut on slightly acidic soil treated with SSPand those treated with MRP whereas there were significantdifferences from those treated with SRP as well as those cuton strongly acidic soil The order of the effectiveness of thesoils and P-sources on dry biomass yield of soybean plantswas SSP gtMRP gt Control gt SRP on slightly acidic soil whileon strongly acidic soil it was MRP gt SSP gt SRP gt Control(Table 5)
Sokoto Rock Phosphate was less than 50 efficient inthe two location soils compared to SSP for the test cropsThe MRP (relative agronomic efficiency RAE of 21024)was more efficient than SSP (100 RAE) in slightly acidicloamy sand but less efficient in strongly acidic sandy clayloam (8817 RAE) compared to SSP (100 RAE) for maize(Table 5) However for soybean (Glycine max L) MRP(362 RAE) was less efficient than SSP (100 RAE) inslightly acidic loamy sand butmore efficient (13977RAE) instrongly acidic sandy clay loam compared to SSP (100RAE)(Table 5)
32 Experiment 2 It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam (Table 6) The soybean-Sorghum crop rotational scheme constantly produced drybiomass yield of Sorghum plants compared to that of maize-Sorghum crop rotational scheme (Table 6) Based on theresidual effects of the various P fertilizer treatments the drybiomass yields of Sorghum plants at first and second cuttingswere not different (Table 6)
For the residual influence of the soils and P-sources therewere no significant differences (119901 lt 005) among the Sorghumdry biomass yield produced on the two soils treated withthe various P-sources and untreated ones at the first andsecond cuttings However similar trend was observed on theinfluence of the crop effects and soils on Sorghum dry biomassyield as those produced on soils and P-sources (Table 7)
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However inslightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants
The relative yields of dry biomass yield of Sorghum insoybean-Sorghum crop effect are greater than those of maize-Sorghum crop effect at both first and second cuttings
The various residual effects of crop effects and P-sourceson dry biomass yield of Sorghum plants were significant(119901 lt 005) at first cutting The highest dry biomass yield ofSorghum plants was gotten from the influence of soybean-Sorghum treated with SSP while the least result was gottenfrom the influence of maize-Sorghum treated with SSP atthe first cutting At the second cutting the influence of cropeffects and P-sources had no significant difference on drybiomass yield of Sorghum plants However inmaize-Sorghumonly MRP was 7813 as efficient as SSP at first cutting ofSorghum plants (Table 8)
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)show that there were no significant differences The implica-tion is that plant vigour and biomass yields did not differ atthe various levels of each of the experimental factors
6 International Journal of Agronomy
Table 7 Influence of the experimental soils and P-source or crop effects and soils on dry biomass yield (gpot) of Sorghum plants in thesecond cropping
TreatmentDry biomass (gpot) Dry biomass (gpot)
Mean Standard deviation RAE () Mean Standard deviation RAE ()First cutting Second cutting
Soils acidity level Phosphate fertilizer
Strongly acidic
Control 192 plusmn052 011 plusmn016Morocco Rock Phosphate 155 plusmn069 13704 007 plusmn008 NDSokoto Rock Phosphate 169 plusmn025 8519 006 plusmn009 NDSingle Super Phosphate 165 plusmn055 100 012 plusmn020 100
Slightly acidic
Control 228 plusmn037 012 plusmn018Morocco Rock Phosphate 246 plusmn081 8571 014 plusmn014 NDSokoto Rock Phosphate 215 plusmn060 ND 02 plusmn028 NDSingle Super Phosphate 249 plusmn114 100 007 plusmn009 100
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
slightly acidic loamy sand tends to produce taller plantscompared to the strongly acidic sandy clay loam (Table 2)
The heights of plants treated with different Phosphorustreatments (sources) were significant (119901 lt 005) differentonly at 5 WAP for maize whereas for soybean significantdifferences were evident at both 5 and 6 WAP The order ofthe magnitude of the performance of the P-sources was SSPgtMRP gt SRP gt Control (Table 3)
There was no significant (119901 lt 005) difference betweenthe dry biomass yields of maize plants treated with SSP andMRP as well as SRP and Control However the dry biomassyield of maize plants treated with SSP or MRP was signif-icantly different from those treated with SRP or Control(Table 4) The same trend was observed on dry biomass yieldin plant tissue of soybean plants as those of the biomass yieldof maize plantsThe order of the effectiveness of P-sources ondry biomass yield of maize plants was MRP gt SSP gt SRP gtControl while that of soybean was SSP gt MRP gt SRP gtControl
Table 4 Influence of P-sources on biomass yield (gpot) and relativeagronomic efficiency (RAE) () of maizesoybean plants in the firstcropping
Treatment Dry biomass (gpot) RAE ()Phosphate fertilizers Maize plantControl 1167Morocco Rock 1843 11438Sokoto Rock 1265 1658Single super 1758 100LSD (5) 239
Soybean plantControl 824Morocco Rock 1142 8503Sokoto Rock 456 NDSingle super 1198 100LSD (5) 249
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
Table 5 Influence of soils and P-sources on dry biomass yield(gpot) and relative agronomic efficiency (RAE) () of maizesoy-bean plants in the first cropping
Treatment Dry biomass (gpot) RAE ()Maize plant
Strongly acidic
Control 420Morocco RP 1240 8817Sokoto RP 857 4699Single SP 1350 100
Slightly acidic
Control 1913Morocco RP 2447 21024Sokoto RP 1673 NDSingle SP 2167 100
LSD (5) 338Soybean plant
Strongly acidic
Control 465Morocco RP 957 13977Sokoto RP 402 NDSingle SP 817 100
Slightly acidic
Control 1183Morocco RP 1326 362Sokoto RP 511 NDSingle SP 1578 100
LSD (5) 353RAE = relative agronomic efficiency of the Phosphorus- (P-) sources =[((yield ofGRPminus yield of Control)(yield of SSPminus yield of Control))times 100]NS = nonsignificantly different at 119901 lt 005ND = not determined
There was significant (119901 lt 005) difference between drybiomass yields of maize plants cut on slightly acidic soilstreated with either SSP or MRP and those treated with SRPor strongly acidic soils treated with P-sources (Table 5) The
International Journal of Agronomy 5
Table 6 Influence of the soils P-source or crop effects on biomass yield (gpot) of Sorghum plants in the second cropping
Phosphate fertilizersControl 21 012Morocco Rock 2 ND 011 50Sokoto Rock 192 ND 013 NDSingle super 207 100 01 100LSD (5) NS NS
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]RY = relative yield of test crop (maize or soybean) = [(yield of the crop on a particular soil typemaximum yield) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
order of the effectiveness of the soils and P-sources on drybiomass yield of maize plants cut on strongly acidic soil wasSSP gt MRP gt SSP gt Control while on slightly acidic soil itwas MRP gt SSP gt Control gt SRP However there was no sig-nificant (119901 lt 005) difference between dry biomass yields ofsoybean plants cut on slightly acidic soil treated with SSPand those treated with MRP whereas there were significantdifferences from those treated with SRP as well as those cuton strongly acidic soil The order of the effectiveness of thesoils and P-sources on dry biomass yield of soybean plantswas SSP gtMRP gt Control gt SRP on slightly acidic soil whileon strongly acidic soil it was MRP gt SSP gt SRP gt Control(Table 5)
Sokoto Rock Phosphate was less than 50 efficient inthe two location soils compared to SSP for the test cropsThe MRP (relative agronomic efficiency RAE of 21024)was more efficient than SSP (100 RAE) in slightly acidicloamy sand but less efficient in strongly acidic sandy clayloam (8817 RAE) compared to SSP (100 RAE) for maize(Table 5) However for soybean (Glycine max L) MRP(362 RAE) was less efficient than SSP (100 RAE) inslightly acidic loamy sand butmore efficient (13977RAE) instrongly acidic sandy clay loam compared to SSP (100RAE)(Table 5)
32 Experiment 2 It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam (Table 6) The soybean-Sorghum crop rotational scheme constantly produced drybiomass yield of Sorghum plants compared to that of maize-Sorghum crop rotational scheme (Table 6) Based on theresidual effects of the various P fertilizer treatments the drybiomass yields of Sorghum plants at first and second cuttingswere not different (Table 6)
For the residual influence of the soils and P-sources therewere no significant differences (119901 lt 005) among the Sorghumdry biomass yield produced on the two soils treated withthe various P-sources and untreated ones at the first andsecond cuttings However similar trend was observed on theinfluence of the crop effects and soils on Sorghum dry biomassyield as those produced on soils and P-sources (Table 7)
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However inslightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants
The relative yields of dry biomass yield of Sorghum insoybean-Sorghum crop effect are greater than those of maize-Sorghum crop effect at both first and second cuttings
The various residual effects of crop effects and P-sourceson dry biomass yield of Sorghum plants were significant(119901 lt 005) at first cutting The highest dry biomass yield ofSorghum plants was gotten from the influence of soybean-Sorghum treated with SSP while the least result was gottenfrom the influence of maize-Sorghum treated with SSP atthe first cutting At the second cutting the influence of cropeffects and P-sources had no significant difference on drybiomass yield of Sorghum plants However inmaize-Sorghumonly MRP was 7813 as efficient as SSP at first cutting ofSorghum plants (Table 8)
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)show that there were no significant differences The implica-tion is that plant vigour and biomass yields did not differ atthe various levels of each of the experimental factors
6 International Journal of Agronomy
Table 7 Influence of the experimental soils and P-source or crop effects and soils on dry biomass yield (gpot) of Sorghum plants in thesecond cropping
TreatmentDry biomass (gpot) Dry biomass (gpot)
Mean Standard deviation RAE () Mean Standard deviation RAE ()First cutting Second cutting
Soils acidity level Phosphate fertilizer
Strongly acidic
Control 192 plusmn052 011 plusmn016Morocco Rock Phosphate 155 plusmn069 13704 007 plusmn008 NDSokoto Rock Phosphate 169 plusmn025 8519 006 plusmn009 NDSingle Super Phosphate 165 plusmn055 100 012 plusmn020 100
Slightly acidic
Control 228 plusmn037 012 plusmn018Morocco Rock Phosphate 246 plusmn081 8571 014 plusmn014 NDSokoto Rock Phosphate 215 plusmn060 ND 02 plusmn028 NDSingle Super Phosphate 249 plusmn114 100 007 plusmn009 100
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
Phosphate fertilizersControl 21 012Morocco Rock 2 ND 011 50Sokoto Rock 192 ND 013 NDSingle super 207 100 01 100LSD (5) NS NS
RAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]RY = relative yield of test crop (maize or soybean) = [(yield of the crop on a particular soil typemaximum yield) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
order of the effectiveness of the soils and P-sources on drybiomass yield of maize plants cut on strongly acidic soil wasSSP gt MRP gt SSP gt Control while on slightly acidic soil itwas MRP gt SSP gt Control gt SRP However there was no sig-nificant (119901 lt 005) difference between dry biomass yields ofsoybean plants cut on slightly acidic soil treated with SSPand those treated with MRP whereas there were significantdifferences from those treated with SRP as well as those cuton strongly acidic soil The order of the effectiveness of thesoils and P-sources on dry biomass yield of soybean plantswas SSP gtMRP gt Control gt SRP on slightly acidic soil whileon strongly acidic soil it was MRP gt SSP gt SRP gt Control(Table 5)
Sokoto Rock Phosphate was less than 50 efficient inthe two location soils compared to SSP for the test cropsThe MRP (relative agronomic efficiency RAE of 21024)was more efficient than SSP (100 RAE) in slightly acidicloamy sand but less efficient in strongly acidic sandy clayloam (8817 RAE) compared to SSP (100 RAE) for maize(Table 5) However for soybean (Glycine max L) MRP(362 RAE) was less efficient than SSP (100 RAE) inslightly acidic loamy sand butmore efficient (13977RAE) instrongly acidic sandy clay loam compared to SSP (100RAE)(Table 5)
32 Experiment 2 It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam (Table 6) The soybean-Sorghum crop rotational scheme constantly produced drybiomass yield of Sorghum plants compared to that of maize-Sorghum crop rotational scheme (Table 6) Based on theresidual effects of the various P fertilizer treatments the drybiomass yields of Sorghum plants at first and second cuttingswere not different (Table 6)
For the residual influence of the soils and P-sources therewere no significant differences (119901 lt 005) among the Sorghumdry biomass yield produced on the two soils treated withthe various P-sources and untreated ones at the first andsecond cuttings However similar trend was observed on theinfluence of the crop effects and soils on Sorghum dry biomassyield as those produced on soils and P-sources (Table 7)
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However inslightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants
The relative yields of dry biomass yield of Sorghum insoybean-Sorghum crop effect are greater than those of maize-Sorghum crop effect at both first and second cuttings
The various residual effects of crop effects and P-sourceson dry biomass yield of Sorghum plants were significant(119901 lt 005) at first cutting The highest dry biomass yield ofSorghum plants was gotten from the influence of soybean-Sorghum treated with SSP while the least result was gottenfrom the influence of maize-Sorghum treated with SSP atthe first cutting At the second cutting the influence of cropeffects and P-sources had no significant difference on drybiomass yield of Sorghum plants However inmaize-Sorghumonly MRP was 7813 as efficient as SSP at first cutting ofSorghum plants (Table 8)
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)show that there were no significant differences The implica-tion is that plant vigour and biomass yields did not differ atthe various levels of each of the experimental factors
6 International Journal of Agronomy
Table 7 Influence of the experimental soils and P-source or crop effects and soils on dry biomass yield (gpot) of Sorghum plants in thesecond cropping
TreatmentDry biomass (gpot) Dry biomass (gpot)
Mean Standard deviation RAE () Mean Standard deviation RAE ()First cutting Second cutting
Soils acidity level Phosphate fertilizer
Strongly acidic
Control 192 plusmn052 011 plusmn016Morocco Rock Phosphate 155 plusmn069 13704 007 plusmn008 NDSokoto Rock Phosphate 169 plusmn025 8519 006 plusmn009 NDSingle Super Phosphate 165 plusmn055 100 012 plusmn020 100
Slightly acidic
Control 228 plusmn037 012 plusmn018Morocco Rock Phosphate 246 plusmn081 8571 014 plusmn014 NDSokoto Rock Phosphate 215 plusmn060 ND 02 plusmn028 NDSingle Super Phosphate 249 plusmn114 100 007 plusmn009 100
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
LSD (5) NS NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005 and ND = not determined
Table 8 Influence of crop effects and P-sources on biomass yield (gpot) of Sorghum in the second cropping
Treatment Dry biomass (gpot) RAE () Dry biomass (gpot) RAE ()First cutting Second cutting
Crop effects Phosphate fertilizer
Maize-Sorghum
Control 181 003Morocco Rock 156 7813 006 NDSokoto Rock 186 ND 006 NDSingle Super 149 100 003 100
Soybean-Sorghum
Control 239 02Morocco Rock 244 ND 015 NDSokoto Rock 198 ND 02 NDSingle Super 264 100 016 100
LSD (5) 066 NSRAE = relative agronomic efficiency of the Phosphorus- (P-) sources = [((yield of GRP minus yield of Control)(yield of SSP minus yield of Control)) times 100]NS = nonsignificantly different at 119901 lt 005LSD = least significant difference (5) and ND = not determined
4 Discussion
41 First Cropping
411 Visual GrowthObservation Crops (maize and soybean)grown in strongly acidic sandy clay loam were not asabundant in growth and yield as those grown in slightly acidicloamy sand where crops in untreated pots had the least plantheight and biomass yield of 59 cm1167 gpot for maize plantand 3539 cm824 gpot for soybean plant respectively Themaize plants grown in untreated pots also developed purplecolouration which is a symptom of Phosphorus deficiency[18] It was observed that SSP treatment supported most
growth (plant height 7483 cm) and biomass 2167 gpot inslightly acidic soil whereas MRP treatment supported mostgrowth (plant height 6317 cm) and biomass yield 1350 gpotin strongly acidic soil for maize plants However for soybeanplants SSP treatment supported the most growth and yieldwith 4363 cm1578 gpot in slightly acidic soil as well as41 cm817 gpot in strongly acidic soil respectively
412 Experimental Data From the results above it wasobserved that values of P in Table 1 imply that both soilswere deficient in P contents since the critical levels rangebetween 10 and 15mgkg P [19 20] The two soil types were
International Journal of Agronomy 7
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
adequately furnished with the same contents of total nitrogen02 where the critical level of nitrogen is 015 [19] Theorganic matter in strongly acidic sandy clay loam (271 gkg)was slightly higher compared to that of slightly acidic loamysand (265 gkg) The exchangeable K was higher in stronglyacidic sandy clay loam (004 cmolkg) when compared to thatof slightly acidic loamy sand (003 cmolkg) both fall withinthe critical range 001ndash015 cmolkg K [19] The stronglyacidic sandy clay loam had lower proportion of sand (628)compared to slightly acidic loamy sandwhich had 871 sandwhile Soil A had higher proportions of silt (15) and clay(222) when compared to Soil B with 4 silt and 89 clay
Slightly acidic loamy sand constantly produced cropswith higher plant height (Table 2) compared to crops grownon strongly acidic sandy clay loam For example crops grownon slightly acidic loamy sand were 5889 cm per plant heighton the average compared to crops grown on strongly acidicsandy clay loam with 4631 cm after 6 weeks of growthSlightly acidic loamy sand was able to support the growth ofthe crops as much as strongly acidic sandy clay loam becauseslightly acidic loamy sand was more fertile than stronglyacidic sandy clay loam The soil pH and clay content valuesfor slightly acidic loamy sand were more suitable for cropsgrowth compared to strongly acidic sandy clay loam Thisis in agreement with the statement made by Akinrinde andAdigun [2] that crops performed better in slightly acidicsoil when compared to medium acid Alfisol Also there ispossibility of higher P-fixation of applied phosphate ions instrongly acidic sandy clay loam than slightly acidic loamysand This is similar to the experiment carried out by Akin-rinde and Adigun [2] quoting Borggard [21] that close linearrelationship exists between clay content and phosphate fixa-tion
Furthermore theControl and SRPhad lesser values for allthe growth component parameters (Tables 3 and 4)The con-ventional soluble P fertilizer (SSP) and one of the rock phos-phates that is MRP almost gave the same result compared toSRP For instance in Table 4 applied MRP significantly gavehigher values of dry biomass 1843 (gpot) for maize plantsthan applied SSP with 1758 (gpot) SRP performed less inthis experiment this could be due to soils type because not allsoils and cropping situations are suitable for direct use of theRPs from different sources [22] For instance this experimentshowed that strongly acidic sandy clay loam treated with SRPgave higher soybean plants than slightly acidic loamy sandtreated with the same SRP though they were not significantlydifferent at 6 WAP (Table 5) SRPrsquos poor performance in thisexperiment could also be attributed to the higher amount ofCaCO
3it contains (79) compared to SSP (35 CaCO
3) and
MRP (14 CaCO3) [23 24] This could increase the soil pH
of the slightly acidic loamy sand from 67 to alkaline soil pHwhich could affect proper functioning of the roots of cropsand lead to poor growth and yieldThis is similar to the resultgotten by Ojo [25] which stated that RPs have more Ca thanSP thus when applied they tend to make the soil alkalineWhile in strongly acidic sandy clay loam the CaCO
3in SRP
helps to increase the soil pH from 53 to slightly acidic soilwhich is favourable to growth of plants However slightlyacidic loamy sand treated with any of the P fertilizers gave
better results in terms of growth and biomass yield of maizeplants than strongly acidic sandy clay loam treated with thesame fertilizer This shows that maize plants could survivein wide range of soil pH compared to soybean plants It alsosupports the fact that differences among P-sources enhancinggrowth and yield components or not are attributed to envi-ronmental plant and soil characteristic factors [2 25 26]The order of the effectiveness of P-sources for the growth andyield of the crops (maize and soybean) is MRP ge SSP gt SRPin the first cropping This shows the P-sources superiority ofP released and availability for plants metabolism
For efficient utilization of RP marked differences havebeen found in the ability of plant species to extract P fromPRs[25 27 28] Similar results were observed in this study whereon average MRP (11438 RAE) was more efficient than SSP(100 RAE) for dry biomass yield of maize (Zea mays L)but for soybean (Glycine max L) dry biomass MRP (8503RAE) was less efficient than SSP (100 RAE) in the two soilsSokoto Rock Phosphate was less than 50 efficient in the twolocation soils compared to SSP for the test crops The MRP(relative agronomic efficiency RAE of 21024) was moreefficient than SSP (100 RAE) in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam (8817RAE) compared to SSP (100 RAE) for maize Howeverfor soybean (Glycine max L) MRP (362 RAE) was lessefficient than SSP (100 RAE) in slightly acidic loamy sandbutmore efficient (13977RAE) in strongly acidic sandy clayloam compared to SSP (100 RAE)
42 Second Cropping It was also observed that slightly acidicloamy sand produced crops with higher dry biomass yieldthan strongly acidic sandy clay loam It could be due to similarreasons given in the first cropping of this experiment
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme This might be as aresult of nitrogen fixed by the leguminous plants which wasused by the following Sorghum plants while cereal-cerealcrop rotational scheme is nitrogen demanding Legumesare used commonly in agricultural systems as a source ofatmospheric N through symbiotic N
2fixation for subsequent
crops maintaining soil nitrogen levels and through subsoilretrieved [29] Rotation of cereals and legumes is usuallypreferred to sole cropping of either crop because of higheryield [30]Therefore it is beneficial to alternate soybean withcereals and other plants that require nitrogen
Based on the residual effects of P fertilizer treatmentthe residual effects of the various P fertilizer treatments onthe dry biomass yield of Sorghum plants at first and secondcuttings did not differ According to the experiment carriedout by Akinrinde and Adigun [2] stated that the P-sourcesproduced significant differences in the height and fresh bio-mass yield but not in the dry matter production
The relative agronomy efficiency (RAE) of MRP instrongly acidic soil was 13704 while SRP was 8519 asefficient as SSP (100)with regard to dry biomass productionat first cutting of Sorghum plants while in the second cuttingRAE of P-sources were undefined (Table 7) However in
8 International Journal of Agronomy
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
slightly acidic loamy sand only MRP was 8571 as efficientas SSP at first cutting of Sorghum plants Rock phosphate ofP dissociation improved with time which in turn improves Pavailability as well as increased yield [25]
The results of the influence of the various interactionsamong the experimental factors (soils crops and P-sources)showed that there were no significant differences The impli-cation is that plant vigour and biomass yields were not differ-ent at the various levels of each of the experimental factors
5 Conclusions
The strongly acidic sandy clay loam produced crops withlower plant height than crops grown in slightly acidic loamysand
The relative agronomic efficiency (RAE) of MRP wasmore efficient than that of SSP in slightly acidic loamy sandbut less efficient in strongly acidic sandy clay loam comparedto SSP as reference fertilizer for maize plants However forsoybean plants MRP was less efficient than SSP in slightlyacidic loamy sand but more efficient in strongly acidic sandyclay loam than SSP
The residual effects of the various P fertilizer treatmentson the dry biomass yield of Sorghum plants at first and secondcuttings were not different
The soybean-Sorghum crop rotational scheme constantlyproduced biomass yield of Sorghum plants compared tomaize-Sorghum crop rotational scheme
However based on points made above it is evident thatpH and clay contents of soils as well as the crop concerneddetermine the efficiency of finely ground soluble phosphatesin crop production as well as positive effects of the crop rota-tion schemes It can serve as means of production of forageor hay for ruminant animal
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
References
[1] M E Sumner and A D Noble ldquoSoil acidification the worldstoryrdquo in Handbook of Soil Acidity Z Rengel Ed pp 1ndash28Marcel Dekker New York NY USA 2003
[2] E A Akinrinde and I O Adigun ldquoPhosphorus-use efficiencyby pepper (Capsicum frutescens) and okra (Abelmoschus escu-lentum) at different phosphorus fertilizer application levels ontwo tropical soilsrdquo Journal of Applied Sciences vol 5 no 10 pp1785ndash1791 2005
[3] K N Fageria ldquoSoil acidity affects availability of NitrogenPhosphorus and Potassiumrdquo Better Crops International vol 10pp 8ndash9 1994
[4] A Rashid ldquoPhosphorus use efficiency in soils of Pakistanrdquo inProceedings of the 4th National Congress of Soil Science SoilScience Society of Pakistan Islamabad Pakistan May 1992
[5] E A Akinrinde and K A Okeleye ldquoShort- and long-termeffects of sparingly soluble phosphates on crop production
in two contrasting Nigerian Alfisolsrdquo West African Journal ofApplied Ecology vol 8 no 1 pp 141ndash149 2005
[6] P A Sanchez A U Mokwunye F R Kwesiga C G Ndirituand P L Woomer ldquoSoil fertility replenishment in africa Aninvestment in natural resource capitalrdquo in Replenishment SoilFertility in Africa R J Buresh Ed vol 51 pp 1ndash46 SSSASpecial 1997
[7] H L S Tandon Phosphorus Research and Agricultural Produc-tion in India 1987
[8] P Pedersen and J G Lauer ldquoInfluence of rotation sequence andtillage system on the optimum plant population for corn andsoybeanrdquo Agronomy Journal vol 94 pp 968ndash974 2002
[9] A R J Eaglesham F R Minchin R J Summerfield P JDart P A Huxley and J M Day ldquoNitrogen nutrition ofcowpea (Vigna unguiculata) 3 distribution of nitrogen withineffectively nodulated plantsrdquo Experimental Agriculture vol 13no 4 pp 369ndash380 1977
[10] A Bationo and A U Mokwunye ldquoAlleviating soil fertilityconstraints to increased crop production in West Africa theexperience in the Sahelrdquo Fertilizer Research vol 29 no 1 pp95ndash115 1991
[11] C P Vance P H Graham and D L Allan ldquoBiological nitrogenfixation phosphorus Ba critical future needrdquo in NitrogenFixation from Molecules to Crop Productivity F O PederosaM Hungria M G Yates and W E Newton Eds pp 509ndash518Kluwer Academic Dordrecht The Netherlands 2000
[12] D J Oyedele O O Awotoye and S E Popoola ldquoSoil physicaland chemical properties under continuous maize cultivationas influenced by hedgerow trees species on an alfisol in SouthWestern Nigeriardquo African Journal of Agricultural Research vol4 no 8 pp 736ndash739 2009
[13] HAAkintoye A AAdekunle andAA Kintomo ldquoThe role oftraining in urban and peri-urban vegetable production the casestudy of Leventis Foundation Agricultural Schools in NigeriardquoLearning Publics Journal of Agriculture and EnvironmentalStudies vol 2 no 2 pp 21ndash40 2011
[14] A J Smyth and R FMontgomery Soils and LandUse in CentralWestern Nigeria Government Printer Ibadan Nigeria 1962
[15] United States Grain Council November Sorghum 2010 httpwwwgrainsorgsorghum
[16] E J Udo and J AOgunwaleLaboratoryManual for theAnalysisof Soil Plants and Water Samples Department of AgronomyUniversity of Ibadan Ibadan Nigeria 1981
[17] O P Engelstad A Jugsujinda and S K De Datta ldquoResponseby flooded rice to phosphate rocks varying in citrate solubilityrdquoSoil Science Society of America Journal vol 38 no 3 pp 524ndash529 1974
[18] K Mengel and E A Kirkby Principle of Plant NutritionInternational Potash Institute Publisher 1987
[19] G O Adeoye and A A Agboola ldquoCritical levels for soil pHavailable P K Zn and Mn and maize ear-leaf content of PCu and Mn in sedimentary soils of South-Western NigeriardquoFertilizer Research vol 6 no 1 pp 65ndash71 1985
[20] R A Solubo andAOOsiname Soils and Fertilizer Use inWest-ern Nigeria Research Bullrtin no 11 Institute of AgricultureResearch and Training University of Ife Ife Nigeria 1981
[21] OK Borggard ldquoIron oxides in relation to phosphate adsorptionby soilsrdquo Acta Agriculturae Scandinavica vol 36 no 1 pp 107ndash118 1986
[22] G O Obigbesan and E A Akinrinde ldquoEvaluation of theperformance of Nigerian rock phosphates applied to millet in
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
[23] E A Akinrinde and G O Obigbesan ldquoBenefits of phosphaterocks in crop production experience on benchmark tropicalsoil areas in Nigeriardquo Journal of Biological Sciences vol 6 no6 pp 999ndash1004 2006
[24] P Van Straaten Rocks for Crops Agro-Minerals of Sub-SaharanAfrica ICRAF Nairobi Kenya 2002
[25] O D Ojo Growth development and yield of amaranth(Amaranthus cruentus L) varieties in response to differentsources of phosphorus [PhD thesis] University of IbadanIbadan Nigeria 2001
[26] D P Schachtman R J Reid and S M Ayling ldquoPhosphorusuptake by plants from soil to cellrdquo Plant Physiology vol 116 no2 pp 447ndash453 1998
[27] E N Flach ldquoA comparison of the rock phosphate mobilizingcapacities of various crop speciesrdquo Tropical Agriculture vol 64pp 347ndash352 1987
[28] S S S Rajan J H Watkinson and A G Sinclair ldquoPhosphaterocks for direct application to soilsrdquoAdvances in Agronomy vol57 pp 77ndash159 1996
[29] S M Gathumbi G Cadisch and K E Giller ldquo15N naturalabundance as a tool for assessing N
2
-fixation of herbaceousshrub and tree legumes in improved fallowsrdquo Soil Biology andBiochemistry vol 34 no 8 pp 1059ndash1071 2002
[30] B O Baldock R L Higgs W H Paulson J A Jackobs and WD Shader ldquoLegume and mineral fertilizer effects on crop yieldsin several crop sequences in the upper Mississipi ValleyrdquoAgronomy Journal vol 73 no 5 pp 885ndash890 1981
