By Mba, Caroline C.
Phosphorous immobilization is among the recalcitrant problems hampering crop production
in the high rainfall acid soils of Nigeria. Applied inorganic phosphorous quickly becomes
immobilized and unavailable to plants. Therefore, there is a need to develop cultural methods
that foster, fast and efficient recycling of phosphorous, and carbon to satisfy plant demands
and facilitate sustainable soil fertility management in these soils. Nine Srreprosporangium
isolates of Eudilius eugeniae (earthworm) casts were found to be acidgenic, acid tolerant, rock
phosphate (RP) solubilizers which could grow on synthetic glucose or carboxymethylcellulose
(CMC) N-free or NH4C1-enriched media, as the sole carbon source. CMC induced
production of extracelluar cellulase enzyme and release of reducing sugar in all isolates. Both
CNC media were acidified by all isolates. The ability to solubilize RP varied among the
isolates and ranged from 800 pg P/g RP/7 days to 9500 j@g RP/7 days. A maximum release
of 1040 pg (glucose equivalent)/mU7 days was recorded in N-free CMC, while a minimum of
121 pglrnl was recorded in NH4Clenriched CMC medium. These isolates could therefore be
exploited in the industrial production of cellulolytic enzymes and microbial phosphate fertilizers
which would enhance organic residues and plant nutrients recycling in acid soils of
Nigeria.