Effect of different organic composts and inorganic fertilizer on nodulation, nitrogen fixation and grain yields of soybean (Glycine max L.) under field conditions.

The study assessed the effects of composted corn wastes, poultry droppings andinorganic fertilizer on the number of nodules, nitrogen fixation and grain yieldsof soybean (Glycine max L.) under field conditions for 2 seasons. The experiments were conducted in the research sub-station of the Institute of AgriculturalResearch and Training, (IAR&T), Ilora, Oyo State, South Western Nigeria:(Derived Savanna Agro-ecology). Six experimental treatments namely; composted corn wastes boiled with table salt, composted corn wastes boiled with wateralone, composted un-boiled corn wastes, composted poultry droppings, NPK 20-10-10 fertilizer and control were applied to a soil with low fertility status. Soybean (Glycine max L.) seeds were planted in a Randomized Complete Block Design (RCBD) and replicated 6 times. The plantings were carried out twice at twoconsecutive plantings. The number of nodules, amount of nitrogen fixed as wellas grain yield were evaluated. The field trial results showed a higher number ofnodules, nitrogen fixation and grain yield response when the un-boiled composted corn wastes (F3) and composted poultry droppings only (F4) were applied tothe field compared to the other treatments. The number of nodules, nitrogen fixation and yield were significantly higher at the end of the second plantings compared to the first reflecting a residual effect of the composts. The study concludedthat the application of composted corn wastes and poultry droppings especiallywhen the seeds were inoculated with Rhizobium and mycorrhiza improved thenumber of nodules, N2 fixation and grain yield of soybean (Glycine max L.) evenwhen no boiling treatment was applied to the corn wastes. It is therefore recommended that maize cobs be converted to composts for improved soil productivity.