EFFECT OF MICRO-ORGANISM ON ROCK PHOSPHATE SOLUBILIZATION IN SOYABEAN AND MAIZE PRODUCTION IN THE NORTHERN GUINEA SAVANNA

EFFECT OF MICRO-ORGANISM ON ROCK PHOSPHATE SOLUBILIZATION IN SOYABEAN AND MAIZE PRODUCTION IN THE NORTHERN GUINEA SAVANNA

Abstract:

The role of micro-organisms in the solubilization of phosphates from Sokoto rock phosphate (SRP), Togo rock phosphate (TPR) and Single super phosphate (SSP) was studied. Phosphate solubilizing organisms were isolated from Samaru soils, screened and selected in a preliminary laboratory studies. Over 120 organisms were isolated, sixty one of them were able to solubilise P. Twenty organisms were observed to solubilise P to an appreciable extent,and thus further studied in the laboratory, out of which ten were selected for greenhouse studies. It was observed that fungi isolates could solubilize phosphate and consequently release 12-28.9 /ug P2Os/g of substrate, while the bacteria isolates released 10.5 – 25.9 ug P2Os/g of substrate. The pattern of phosphorus release varied among the organisms and the length of immobilization also differed. While F21 was able to release a range of 18.3 – 60.8 ug P2Os/g of substrate in 6 weeks of incubation, another organism, F2U, released 20.9 – 33.8 ug P2Os/g of substrate. Ten micro-organisms (5 bacteria and 5 fungi) were selected for further study in the greenhouse. Maize and soyabean were used as test crops in the greenhouse study. Results from the greenhouse showed that SSP was superior to the rock phosphates in plant height, leaf area and dry matter yield in soyabean at the first cropping. Residual effect of rock phosphate was however, superior to SSP.TPR gave 20% and 3% superior values when cropped to soyabean and maize respectively. Soyabean also responded to inoculation at first cropping and also at second cropping, the magnitude of response was however, more at the second cropping. The results obtained for maize showed that the inoculation of organisms resulted in retardation of maize growth at first cropping. Whereas, the organisms promoted maize growth at the second cropping. However in soyabean, inoculation of organisms to SSP, Togo rock and Sokoto rock resulted in crop response at both first and second croppings. Among the ten organisms tested in the green house, five were selected for field studies. The organisms were identified as Rhizopus sp, Aspergillus niger, Penicillium sp, Pseudomonas striata and Bacillus megaterium. The results obtained in the field showed that Togo rock phosphate was superior to SSP in soyabean grain production. Togo rock phosphate produced yields of 2,132 kg/ha,compared to 1,931 Kg/ha, and 1,909 Kg/ha produced with SSP and SRP. Rhizopus sp and P. striata inoculation resulted in higher yields than the other organisms. These two organisms gave increases of 351 Kg/ha and 345 Kg/ha above uninoculated plots. Inoculation of Rhizopus sp, B. megaterium and P. striata in SSP was observed to enhance its performance. Togo rock phosphate was enhanced by A. niger and Penicillium sp while Sokoto rock phosphate was enhanced by inoculation with P. striata. The maize crop on the other hand responded more to SSP than the rock phosphates. Yield differences of 975 Kg/ha and 1390Kg/ha were recorded between SSP and Togo rock phosphate and SSP and SRP respectively. However, only inoculation with A. niger and P. striata favoured maize grain yield production. SSP alone was favoured by inoculation of micro-organisms. No significant response was recorded to rock phosphates in combination with inoculation. Inoculation studies showed that P immobilization proceeds for 8 weeks after inoculation prior to substantial P release into the soil. A study ofthe effect of inoculants on mycorrhiza showed that inoculation influenced root infestation by mycorrhiza, and the subsequent development of mycorrhizal organism depended on the organism inoculated.

EFFECT OF MICRO-ORGANISM ON ROCK PHOSPHATE SOLUBILIZATION IN SOYABEAN AND MAIZE PRODUCTION IN THE NORTHERN GUINEA SAVANNA

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