POTENTIALS OF MYCORRHIZA (Glomus mosseae) AS A BIOFERTILIZER IN THE CULTIVATION OF COWPEA (Vigna unguiculata L. Walp)

Transcription

1 POTENTIALS OF MYCORRHIZA (Glomus mosseae) AS A BIOFERTILIZER IN THE CULTIVATION OF COWPEA (Vigna unguiculata L. Walp) ABSTRACT Ofili *, V. I., Orhue, E. R. and Ogboghodo, I. A. Department of Soil Science, Faculty of Agriculture University of Benin, Benin City. 1 Corresponding author lerieo@yahoo.com, phone number: (234) A field experiment was carried out to evaluate the potentials of mycorrhiza (Glomus mosseae) as a biofertilizer in the cultivation of cowpea (Vigna unguiculata). The study examined the effects of inoculating soil with mycorrhiza (Glomus mosseae) on some soil properties, nutrient uptake, mycorrhiza root infection and some growth parameters of cowpea (Vigna unguiculata). The experiment was carried out on a previously cropped unfertilized cassava (Manihot esculenta) farm. An area measuring 13 m x 11 m was used in this trial. Seven treatments namely; control, mycorrhiza (MYC), NPK 15:15:15 (NPK), poultry droppings (PD), mycorrhiza + NPK 15:15:15 (NM), mycorrhiza + poultry droppings (MPD), mycorrhiza + poultry droppings + NPK 15:15:15 (NMPD) were used. Each of these treatments represented by a plot size of 1m x 1m was replicated six times and laid out in a Randomised Complete Block Design. Vine length, number of leaves, number of pods, yield and number of viable nodules were measured and soil samples analysed before and after the trial. Results showed that at fourteen weeks after sowing (14 WAS), vine length, number of leaves in the treated plants were significantly (P < 0.05) higher than other treatments. The MYC, PD, NM, MPD and NMPD were significantly higher (P < 0.05) than other treatments in soil ph, organic carbon, N, P, Na and P. In Mg and K, the NPK treatment was significantly higher than other treatments while the PD treatment was higher in the calcium component of the soil compared to the other treatments. The control and NPK applications were significantly higher in exchangeable acidity whereas significantly higher ECEC was achieved in PD treatments compared to others. The viable nodules and grain yield were significantly higher in MPD treated plants compared to other treatments. In the case of nutrient content, significantly N, P and K were recorded at NMPD application while significantly higher K uptake was achieved at NM treatment. Significantly higher spores, root arbuscules, root vessicles and root hyphae were achieved in MYC, NM, MPD and NMPD compared to control, NPK and PD treatments. Keywords; biofertilizer, cowpea, mycorrhiza, poultry droppings. INTRODUCTION The continuous use of fertilizer for maximum crop yield is a global concern. It is compounded by the fact that most tropical soils have low nutrient status which necessitates the use of fertilizers for intensive cropping systems (Adetunji, 1991). Though inorganic fertilizers release nutrients faster, they increase soil acidity as well as induce cytological defects in crops (Tabur and Oney, 2009). In addition, the cost of inorganic fertilizer is becoming increasingly higher, resulting in high costs of crop production. The negative effects of inorganic fertilizers on soil properties and environment have led to the search for alternatives. Although organic manure such as poultry droppings would seem to be a good substitute for inorganic fertilizers, they have been associated with disease incidences in crops since they sometimes harbour pathogenic residues. Also, not all macro and micro nutrients in the manure are readily available for plant uptake and this could bring about slow growth and poor yield of crops. Mycorrhizae, form symbiotic relationships with the roots of plants where they facilitate water and nutrient uptake while benefitting from the carbon compound provided by the host plant. They also have synergistic interaction with other beneficial microorganisms such as nitrogen-fixers and phosphorus-solubilizers (Sreenivasa and Bagyaraj, 1989). The ability of cowpea (Vigna unguiculata) to fix nitrogen requires supplemental supply at initial developmental stages prior to commencement of fixation especially in the soils of very low nitrogen status. Cowpea also needs phosphorus fertilization because most tropical soils are low in available phosphorus which is critical to cowpea yield because of its multiple effects on nutrition and nodulation (Okeleye and Okelana, 1997). Hence, the objective of this study was to determine the comparative effect of mycorrhiza inoculation, NPK 15:15:15, poultry droppings and their combinations on some soil chemical properties, growth and yield of cowpea. MATERIALS AND METHODS Site of the study The study site was situated at Benin City which is under the influence of tropical climate. The city lies between latitude 6 34' North and longitude 5 63 ' East and 80 meters elevation above sea level. It has two major seasons namely, the rainy (April October) and dry (November March). The peak of the rainy season is usually NJAFE VOL. 10 No. 3,

2 between July and September with a brief drop in August. The mean annual rainfall is 2500 mm (NIMET, 2011) and average daily temperature of about 32 ºC. The City has a mean relative humidity of about 70%. Benin City is both commercial and agrarian city where different types of crops are produced. The experimental site is located at latitude 6 o N and longitude 5 o E. Field trial The plot was cleared manually and the debris removed. Beds measuring 1m by 1m represented a plot. The plots were replicated six times. Each plot was separated by 50 cm alley while each replicate was separated by 60 cm alley. There were a total of seven treatments and six replicates. The treatments include control, mycorrhiza (MYC), NPK 15:15:15 (NPK), poultry droppings (PD), mycorrhiza and NPK 15:15:15 (NM), mycorrhiza and poultry droppings (MPD), mycorrhiza, poultry droppings and NPK 15:15:15 (NMPD). This trial was organised in a Randomised Complete Block Design. The poultry droppings were applied to soil after curing for 8 weeks at the rate of 50,000 kg per ha. The NPK fertilizer was applied at the recommended rate of 100 kg NPK 15:15:15 per ha. The clods of mycorrhiza inoculum were crushed and applied at the rate of 5,000 kg per ha. Sowing was at spacing of 60 cm by 25 cm. Weeding was done every week for about four weeks and later reduced to once in three weeks after emergence of the crop. Data were collected on vine length and number of leaves weekly. When fruiting began, data were collected weekly on number of pods per plant and after harvest, the numbers of pink nodules per plant were counted and yield was also calculated per hectare. Soil physical and chemical analyses were carried out before and after the trial. Nutrient content and uptake were determined at the end of the trial. Mycorrhiza spore count was determined before planting, during flowering and after harvest, while mycorrhiza root count was determined during flowering and at the end of the trial. Soil samples were collected before sowing and at the termination of the experiment. Laboratory analysis Soil ph was determined in a 1:1 soil to distilled water suspension using a glass electrode ph meter as described by Thomas (1996). Particle size analysis was carried out by the hydrometer method of Bouyoucous (1951) as modified by Day (1965). Organic Carbon content of the sample was determined by the Walkley and Black (1934) chromic acid and wet oxidation procedure as described by Grewling and Peach (1965) in Black (1965). Total Nitrogen was extracted by the micro-kjeldahl digestion procedure and the nitrogen was measured by the indophenols method of Scheiner (1976). Available Phosphorus was extracted with Bray and Kurtz (1945) solution and the available phosphorus in the extract was determined calorimetrically by the molybdenum blue colour method of Murphy and Riley (1962). Exchangeable Bases were extracted with 1 N neutral ammonium acetate solution. Calcium and magnesium were determined by atomic absorption spectroscopy as described by Ramirez Munoz (1968) while potassium (K) and sodium (Na) in the extract was determined with flame photometer. Exchangeable Acidity was determined by the KCl volumetric procedure by Mclean (1982). Effective Cation Exchange Capacity was determined by summation of the exchangeable bases (Na, K, Ca, and Mg) and the exchangeable acidity. Determination of mycorrhiza spore count and root infection Mycorrhiza spore count was determined using the decantation procedure (Gerdemann and Nicolson, 1963) as modified by Muthukumar et al. (1996). Samples were examined under a microscope with 150 point view. In the determination of root infection, the roots of cowpea were first preserved in Formalin Acetic Acid (FAA) before the mycorrhiza root count was determined according to the procedure of Phillips and Hayman (1970). Nitrogen and crude protein determination Fifty grams (50 g) ground plant material was digested with concentrated H 2 SO 4 acid. The digested plant material was diluted and filtered. The filtrate was used in the nitrogen determination by the alkaline-phenate colorimetric procedure (Fiore and O Brien, 1962). Crude Protein was calculated by multiplying the nitrogen content by 6.25 (Mossé, 1990). Phosphorus and Potassium determination Fifty grams (50 g) was digested with a mixture of HNO 3, HClO 4 and H 2 SO 4. The mixture was heated until heavy fumes of perchloric acid were given off and the digest turned completely clear. The digest was diluted with distilled water and filtered. The filtrate was used for P and K determination. Phosphorus was determined in a 5 ml aliquot of the filtrate by vanadomolybdate yellow colour method of Kitson and Mellon (1944) as modified by Juo (1979), while potassium was determined in the filtrate by photometry. Statistical analysis The data obtained were subjected to analysis of variance and significantly different treatment means were separated at 5% level of probability using Duncan multiple range test. NJAFE VOL. 10 No. 3,

3 RESULTS Pre-trial soil, poultry manure properties and mycorrhiza spore count Tables 1, 2 and 3 present the pre-trial properties of soil, poultry manure and mycorrhiza spore count. The pre-trial soil is loamy sand in texture, ph 5.8, with organic carbon 8.22 gkg -1, total nitrogen 1.55 gkg -1 and available phosphorus 3.77 mgkg -1. These values for organic carbon, total nitrogen and phosphorus are low according to Udo et al. (2009).The poultry manure used was alkaline (ph 8.6) with carbon to nitrogen ratio 6:1 and available phosphorus had a mean value of mgkg -1. Although there were mycorrhiza spores in the soil before treatment application and planting, there were no mycorrhiza roots (arbuscules, vesicles and hyphae) present in the soil. Table 1: Chemical properties of poultry manure used in the trial Table 2: Some physical and chemical properties of the soil used in the trial Property ph 8.6 Value Organic carbon (g kg -1 ) Total Nitrogen (g kg -1 ) C:N ratio 6:1 Available Phosphorus (mg kg -1 ) Exchangeable Calcium (cmol kg -1 ) 0.12 Exchangeable Magnesium (cmol kg -1 ) 0.19 Table 3: Mycorrhiza spore count of the soil (spores g -1 ) before the trial Treatments Spores Control NPK MYC 3.77 a PD NM 4.0 a MPD NMPD 4.00 a Values with same subscript in the column are not significantly different at P<0.05; Key; NPK: NPK 15:15:15, MYC: mycorrhiza, PD: poultry droppings, NM: NPK 15:15:15 + mycorrhiza, MPD: mycorrhiza + poultry droppings, NMPD: NPK 15:15:15 + mycorrhiza+ poultry droppings Property Sand (g kg -1 ) Silt (g kg -1 ) Clay (g kg -1 ) ph (H 2 O)1:1 Organic Carbon (g kg -1 ) Total Nitrogen (g kg -1 ) Available Phosphorus (mg kg -1 ) Exchangeable Calcium (cmol kg -1 ) Exchangeable Magnesium (cmol kg -1 ) Exchangeable Potassium (cmol kg -1 ) Exchangeable Sodium (cmol kg -1 ) Exchange Acidity (cmol kg -1 ) E.C.E.C. (cmol kg -1 ) Value Post-trial soil chemical properties Table 4 shows the effect of the treatments on some soil chemical properties. Significantly higher (P< 0.05) soil ph, organic carbon, N and P components were recorded in NMPD treatments after the trial. However in organic carbon, there was no significant difference between the MPD and NMPD. While significantly higher Ca, Mg, K, Na, exchangeable acidity and ECEC were attained in PD, NPK, NM, Control and MPD respectively. Table 4: Post trial physical and chemical properties of the soil Treatment Sand Silt Clay ph (H 20) Org.Carbon N P Ca Mg K Na Ex. Acidity ECEC g kg g kg mg kg cmol kg Control 883 b 40 a 77 ab 5.77 e 2.51 d 0.05 f 1.13 f 1.02 f 0.31 c 0.09 f 0.06 f 1.05 a 3.07 d NPK 886 ab 40 a 80 a 5.80 e 2.80 d 0.17 e 1.19 f 2.54 c 0.90 a 0.76 a 0.06 f 0.29 b 4.55 ab MYC 883 b 40 a 77 ab 6.63 b 3.62 c 0.23 d 4.64 e 1.40 e 0.53 d 0.09 f 0.07 e 0.00 b 2.09 e PD 880 bc 40 a 80 a 6.70 b b 0.40 c c 4.77 a 0.52 d 0.36 d 0.14 b 0.00 b 5.79 a NM 889 a 40 a 71 b 6.23 d b 0.61 bc d 2.24 d 0.61 c 0.39 c 0.80 a 0.00 b 4.04 c MPD 887 ab 40 a 73 ab 6.50 c ab 0.71 b b 2.91 b 0.80 b 0.42 b 0.12 c 0.00 b 4.25 b NMPD 890 a 40 a 70 c 6.87 a a 0.77 a a 3.14 b 0.66 c 0.30 e 0.10 d 0.00 b 4.20 b Key: NPK = NPK 15:15:15, MYC = mycorrhiza, PD = poultry droppings, NM = NPK 15:15:15 + mycorrhiza, MPD = mycorrhiza + poultry droppings, NMPD = NPK 15:15:15 + mycorrhiza + poultry droppings. NJAFE VOL. 10 No. 3,

4 Effect of the treatments on the vine length, number of leaves and number of pods Figures 1, 2 and 3 show the effect of treatments on vine length, number of leaves and number of pods. The MPD treatment had the longest vine length (Fig. 1) followed by the MYC throughout the duration of the experiment. At weeks 7 13, the vine length of the control and NPK treatments were not significantly different from each other. At week 6, there was no significant difference in the number of leaves (Fig. 2) among the treatments but at weeks 7, 8 and 9, NMPD treatment had the highest number of leaves followed by the MYC and MPD treatments. However, at week 10, the MPD and MYC had the highest number of leaves while at week 14, the NMPD and MPD had the highest leaf number. In the case of the number of pods (Fig. 3), there were no significant differences in the number of pods at 9, 11 and 12 weeks. Though at 10 weeks the MPD and MYC treatments had the highest number of pods while at 13 and 14 weeks, the highest number of pods were recorded for the NMPD and MPD treatments. Fig. 1: Effect of treatments on vine length (cm) Fig. 2: Effect of treatments on number of leaves Table 5: Effect of the treatments on the grain yield and number of viable nodules Fig. 3: Effect of the treatments on number of pods Treatment Grain yield (kg ha -1 ) Viable nodules Control c 4.00 c NPK bc 5.00 c MYC ab 9.00 ab PD b 9.00 ab NM bc 8.00 b MPD a a NMPD ab 9.00 ab Values with same subscript down the column are not significantly different at P<0.05. NPK: NPK 15:15:15, MYC: mycorrhiza, PD: poultry droppings. NM: NPK 15:15:15 + mycorrhiza, MPD: mycorrhiza + poultry droppings, NMPD: NPK 15:15:15 + mycorrhiza +poultry droppings Effect of the treatments on number of viable nodules and grain yield Table 5 shows the effect of treatments on the number of nitrogen fixing nodules and grain yield. The MPD had the highest number of pink nodules followed by the MYC, PD and NMPD compared to control. Significantly higher grain yield was recorded also in MPD, NMPD and MYC compared to control. However, higher value of grain yield was attained in MPD. Effect of treatments on mycorrhiza spore and root infection count at flowering and harvest Table 6 shows the effect of the different treatments on mycorrhiza spore and root (arbuscules, vessicles and hyphae) at flowering. At flowering, the NMPD had the highest number of mycorrhiza spores while the MPD had the highest number of arbuscules, vessicles and hyphae followed by the NMPD. At harvest, there was no significant difference between treatments in the number of spores. There were more arbuscules in the MPD, NMPD and MYC while the MPD had the highest number of hyphae. Effect of the treatments on the nutrient content, uptake and crude protein component of the plant Table 7 shows the nutrient uptake and crude protein component of the plant. Significantly higher N, P, and K content of the plant were achieved in NMPD, MYC and NM respectively compared to control. While in the NJAFE VOL. 10 No. 3,

5 uptake, significantly higher N and P uptake were recorded in NMPD. Significant K uptake was however reported in NM treatment. In the case of crude protein content of the plant, the NPMD treatment was significantly higher than other treatments. Table 6: Effect of treatments on mycorrhiza spore and root infection count at flowering and harvest (Spores g -1 ) Treatments Spores arbuscules At flowering vessicles hyphae Spores arbuscules At harvest vessicles hyphae Control 5.00 b 4.00 d 7.00 c 7.00 d 4.67 a 2.00 c 3.50 b 3.50 d NPK 6.33 ab 5.00 cd 7.00 c 8.00 d 5.33 a 2.50 bc 3.50 b 4.00 d MYC 9.67 ab b b b 6.67 a 7.00 ab 8.00 ab 9.50 b PD 7.00 ab 6.00 c 9.00 c c 5.67 a 3.00 bc 4.50 b 6.50 c NM 9.33 ab bc 8.00 c cd 6.67 a 5.00 b 4.00 b 5.00 cd MPD 9.67 ab a a a 7.00 a 9.50 a a a NMPD a b ab 9.17 a 9.00 a 7.00 b ab Values with same subscript down the column are not significantly different at P NPK: NPK 15:15:15, MYC: mycorrhiza, PD: poultry droppings, NM: NPK 15:15:15 + mycorrhiza, MPD: mycorrhiza + poultry droppings NMPD: NPK 15:15:15 + mycorrhiza +poultry droppings. Table 7: Effect of the treatments on the plant nutrient content, uptake and crude protein Nutrient content Nutrient uptake Treatments N P K CP N P K Control 0.22 g 0.29 d 0.46 f 1.36 g 0.70 g 1.07 e 1.46 g NPK 2.05 c 0.3l c 1.08 d c f b f MYC 2.18 b 0.3l c 1.19 c b b b e PD 1.53 d 0.37 a 1.04 e 9.56 d d d d NM 0.97 f 0.34 b 1.24 b 6.08 f e c b MPD 1.5l e 0.33 b 1.09 d 9.42 e c a c NMPD 2.5l a 0.39 a 2.30 a a a b a Note: Mean values followed by same subscript down the column are not significantly different at P Key; NPK: NPK 15:15:15, MYC: mycorrhiza, PD: poultry droppings. NM: NPK 15:15:15 + mycorrhiza, MPD: mycorrhiza + poultry droppings. NMPD: NPK 15:15:15 + mycorrhiza +poultry droppings, N: Nitrogen, P: Phosphorus, K: Potassium, CP: Crude Protein. DISCUSSION The properties of the soil used indicated that the soil was acidic and low in fertility. The N, P and K were below the critical level reported by Udo et al. (2009). The inoculation of the soil with mycorrhiza and the various amendments which resulted in an increase in soil ph can be related with the findings of Garbaye (1994). Increase in available P may be attributed to the application of MYC, and the combination with PD and NPK fertilizer. Agbede et al. (2008) reported that poultry droppings, increased soil nutrient status as shown by increase in soil N, P, K, Ca and Mg. Higher soil N content was achieved probably due to the fixation by cowpea plant. Also, through the spread of extra-radical mycorrhizal hyphae, unavailable P was hydrolysed for plant use. However, similar increase in soil P has been reported by Carlile et al. (2001) when they treated the soil with arbuscular mycorrhiza. The combination of arbuscular mycorrhiza, poultry droppings and NPK led to increased N and P uptake by the plant may be due to the presence of the mycorrhiza in the combinations. The higher uptake of P may be due to the capacity of mycorrhiza to absorb phosphate from the soil and transfer to host roots. Similar increases by plants treated with MYC have earlier been reported by Abbot and Robson (2006) and Rohyadi et al. (2004). The enhancement of vine length, number of leaves, pods and nodules by MYC may be attributed to higher nutrient uptake by the plant. This result is in agreement with the findings of Faria (1995), Deshmukh et al. (2007) and Avis et al. (2008). Hamel (2004) however stated that effective mycorrhiza colonization can also increase the nodulations and symbiotic nitrogen fixation in inoculated legumes. The significantly higher grain yield in MPD compared to other treatments suggested that arbuscular mycorrhiza and poultry droppings combinations can be compared favourably with NPK and conveniently replace NPK in the cultivation of cowpea in the soil. This higher yield further confirms earlier reports of Tabassum et al. (2011) and Olawuyi et al. (2011). The increase in mycorrhiza spores, arbuscules, vesicles and hyphae in MYC, PD, NM, MPD and NMPD compared to control and NPK treatments may be attributed to the presence of soil nutrients for mycorrhizal sporulation and hyphal NJAFE VOL. 10 No. 3,

6 development. Douds et al. (2000) have earlier reported that P concentrations in the soil increase hyphal growth and branching as well as induce plant exudation of compounds that control hyphal branching intensity. CONCLUSION This experiment showed that the combination of mycorrhiza with NPK and PD significantly increased the pod number, number of viable nodules, vine length, and number of leaves of the cowpea plant. It also improved the mycorrhiza root count in the soil. Similarly, the nutrient content (N, P, K, Mg) of the soil were also improved. Based on these results, it could be concluded that addition of mycorrhiza (Glomus mosseae) to the soil is good for cowpea cropping. REFERENCES Abbott, L. K. and Robson, A. D The role of arbuscular mycorrhizae fungi in agriculture and the selection of fungi for inoculation. Australian J. Agric. Res. 231: Adetunji, M. T An evaluation of the soil nutrient status for maize production in South Western Nigeria. J. Agric. Res. 8: Agbede, T. M., Ojeniyi, S. O. and Adeyemo, A. J Effect of poultry manure on soil physical and chemical properties, growth and grain yield of sorghum in Southwest Nigeria. Am. Eur. J. Sustainable Agric. 2: Avis, T. J. Gravel, V., Antoun, H. and Tweddel, R. J Multifaceted beneficial effects of rhizosphere microorganisms on plant health and productivity. J. Soil Biol. Biochem. 40(7): Black, C. A Methods of Soil Analysis Agronomy Part 3, America Society of Agronomy, Madison, Wisconsin. Bouyoucous, G. H A recalibration of the hydrometer method for making mechanical analysis of soil. Agron. Journal 43: Bray, R. H. and Kurtz, L.T Determination of total organic and available forms of phosphorus in soils. Soil Sci. 59: Carlile, M. J., Watkin, S. C. and Graham, W. G The fungi. 2nd ed. Elseiver Academic Press.San Diego California Academic press. 1055pp. Day, P. R Particle Fractionating and particles size analysis. In methods of Soil Analysis, part 1, Agronomy 9: Deshmukh, A. M., Khobragade, R. M. and Dixit-Jaipur P. P Handbook of Biofertilizers and Biopesticides. Oxford Book Company. 308pp. ISBN Douds, D. D. Pfeffer, P. E. and Shachar Hill F Carbon partitioning cost and metabolism of arbuscular mycorrhiza in: Arbuscular mycorrhizas, Physiology and function, molecular Biology and Physiology. Kluwer academic publishers. The Netherlands p. Faria, S. M Occurence and rhizobial selection for legumes adapted to acid soils. In: Nitrogen Fixing Trees for Acid Soils. Nitrogen Fixing Tree Research Reports (special issue) Fiore, J. and O Brien Ammonia determination by automatic analysis. J. Wastes Engineering. 33 : 352. Garbaye, J Helper bacteria: a new dimension to the mycorrhizal symbiosis. New Phytologist. 128: Gerdemann, J. W. and Nicolson, T. H Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Trans. Br. Mycol. Soc. 46: Grewling, T. and Peach, M Chemical soil tests. Cornel University, Agricultural Experiment Station Bulletin. 960: Hamel, C Impact of Arbuscular fungi on N and P cycling in the root zone. Canadian J. Soil Sci. 84(4): Juo, A. S. R Selected Methods for Soil and Plant Analysis. Manual Series No. 1.International Institute of tropical Agriculture, Ibadan, Nigeria. Pages 70. Kitson, R. E. and Mellon, M. G Colourimetric determination of phosphorus as molybdivanado-phosphoric acid. J. Ind. Eng. Chem. 16 : 379. Mclean, E. O Soil ph and lime requirements. In Methods of Soil Analysis, Part 2. Chemical and Microbiological Properties. Ag. Monograph No. 9, 2nd Edition. Mossé, J Nitrogen to protein conversion factor for ten cereals and six legumes or oil seeds. A reappraisal of its definition and determination. Variation according to species and to seeds protein content. J. Agric and Food Chemistry 38: Murphy, J. and Riley, H. P A modified single solution method for the determination of phosphate in natural waters. Anal. Chem. Acta.27: NJAFE VOL. 10 No. 3,

7 Muthukumar, T., Udaiyan, K. and Manian, S Vesicular arbuscular mycorrhizae in tropical sedges of Southern India. J. Biology and Fertility of Soils 22: Nigerian Meteorological Agency (NIMET) Seasonal Rainfall Prediction (SRP). (accessed November, 2012). Okeleye, K. A. and Okelana, M. A. O Effect of phosphorus fertilizer on nodulation, growth and yield of cowpea (Vigna unguiculata (L.) Walp.) varieties. Indian J. Agric. Sci., 67: Olawuyi, O. J., Babatunde, F. E., Akinbode, O. A., Odebode, A. C. and Olakojob, S.A Influence of Arbuscular mycorrhiza and NPK fertilizer on the productivity of cucumber (Cucumis sativus), International Journal of Organic Agricultural Research and Development 3: Pal, U. R Effect of source and rate of nitrogen and phosphorus on yield, nutrient uptake and apparent fertilizer nutrient recovery by maize in Southern Guinea Savannah. J. Agric. Sci. and Tech. Vol. 1 (1): Phillips, J. M. and Hayman, D. S Improved procedures for cleaning root and staining parasitic and vesicular arbuscular mycorrhizal fungi for rapid assessment of infection. Transactions of the British Mycological Society. 55: Ramirez-Munoz, J Atomic absorption Spectroscopy and analysis by Atomic absorption plane Photometry. Elsevier Publishing Co., NY, page Rohyadi, A., Smith, F. A., Murray, R. S. and Smith, S. E Effects of ph on mycorrhizal colonization and nutrient uptake in cowpea under conditions that minimise confounding effects of elevated available aluminium. J. Plant and Soil. 260: Scheiner, D Determination of ammonia and Kjeldahl nitrogen by indophenol method. Water Res. 10: Sreenivasa, M. N. and Bagyaraj, D. J Use of pesticides for mass production of vesicular arbuscular mycorrhizal inoculum. J. Plant and Soil. 119 (1): Tabassum, Y., Tanvir, B. and Farmukh, H Effect of arbuscular mycorrhizal inoculation on nutrient uptake, growth and productivity of cowpea (Vigna unguiculata) varieties. African J. Biotech. 10: Tabur, S. and Oney, S Effect of artificial fertilizers on mitotic index and chromosome behaviour in Vica hybrida L. J. Agric. Research. Vol 47. 1: 1-9. Thomas, G. W Soil ph and soil acidity In Method of Soil Analysis. Part 3. ASA Monogr. 9. ASA and SSSA. Udo, J. E., Ibia, T. O., Ogunwale, J. A., Ano, A. O. and Esu, I. E Manual of Soil, Water and Plant Analysis. Sibon Books Limited. 183pp. Walkley, A. and Black, I. A An experiment of the degtjareff method for determining soil organic matter and proposed modification of the chromic acid titration method. Soil Science 37: NJAFE VOL. 10 No. 3,