Response of three soils in the derived savanna zone of southwestern Nigeria to combined application of organic and inorganic fertilizer as affecting phosphorus fractions

Abstract

Phosphorus inputs to the soil are primarily from the application of fertilizer P and organicresources. A ten week incubation study was carried out to determine the effects of organicand inorganic P sources on phosphorus fractions in three derived savanna soils. Poultrymanure was applied at 0, 0.75g, 1.5g, 2.25g and 3g per 300g weight of soil while singlesuperphosphate was applied at 0.0023g, 0.0046g, 0.0069g and 0.0092g per 300g of soil.Sampling was done at two weeks interval. At 0 week of the incubation study, Ekiti serieshad the largest amount of P fractions i.e. Fe-P, Al-P, residual P, reductant soluble P,occluded P, organic P and occluded P while Ca-P was high in Apomu series. However,increases in Fe-P, Al-P, Ca-P and organic P were observed in the three soil series evaluatedand poultry manure was notably effective in reducing P occlusion. In conclusion, it wasobserved that irrespective of the soil series at different stages of the incubation studies,poultry manure and the combined application of poultry manure and Singlesuperphosphate was highly effective in increasing P fractions.