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

Abstract

The study assessed the effects of composted corn wastes, poultry droppings and inorganic fertilizer on the number of nodules, nitrogen fixation and grain yields of soybean (Glycine max L.) under field conditions for 2 seasons. The experiments were conducted in the research sub-station of the Institute of Agricultural Research 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 water alone, 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 two consecutive plantings. The number of nodules, amount of nitrogen fixed as well as grain yield were evaluated. The field trial results showed a higher number of nodules, nitrogen fixation and grain yield response when the un-boiled composted corn wastes (F3) and composted poultry droppings only (F4) were applied to the 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 concluded that the application of composted corn wastes and poultry droppings especially when the seeds were inoculated with Rhizobium and mycorrhiza improved the number of nodules, N2 fixation and grain yield of soybean (Glycine max L.) even when no boiling treatment was applied to the corn wastes. It is therefore recommended that maize cobs be converted to composts for improved soil productivity.