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
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Date
1997
Authors
BABALOLA, OLUWATOYIN ABIMBOLA
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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.
Description
A Dissertation submitted to The Postgraduate School in Partial Fulfillment of the
Requirements for the Award of the Degree of Doctor of Philosophy (Soil Science)
Department of Soil Science
Ahmadu Bello University
Zaria, Nigeria
Keywords
EFFECT,, MICRO-ORGANISM,, ROCK,, PHOSPHATE,, SOLUBILIZATION,, SOYABEAN,, MAIZE,, PRODUCTION,, NORTHERN GUINEA SAVANNA