Soil Fertility, Phosphorus Fractions, and Maize Yield as Affected by Poultry Manure and Single Superphosphate.

A field experiment was conducted in 2007 and 2008 on a slightly acidic alfisol. Poultry manure (PM) was applied at 0, 5 t ha(-1), 10 t ha(-1), 15 t ha(-1), and 20 t ha(-1) in combination with SSP at 0, 15 kg P ha(-1), 30 kg P ha(-1), 45 kg P ha(-1), and 60 kg P ha(-1), which was replicated three times. The pH and organic C were significantly increased by the application of PM alone while available P was highly increased by the sole application of SSP. Plant tissue P was significantly increased with the application of 30 kg P ha(-1) while the largest grain yield was obtained when PM at 20 t ha(-1) was combined with SSP at 60 kg P ha(-1). The buildup of organic P was observed when PM was applied at 15 t ha(-1) while the combination of the two treatments increased residual P and Fe-P. However, P occlusion was effectively reduced with the sole application of PM. Organic P and residual P however had a strong positive relationship with the grain yield. Comparing the sole and combined application of the treatments, the combined application was more effective for most of the parameters observed.