Kolawole, G.; Adigun, C.; Akintade, B.; Opaleye, O.; Lawal, B. Organic Residues Affect Soil P Availability, Cowpea Yield And Nutrient Uptake on a Near Neutral P-Deficient Alfisol in Southwestern Nigeria. Int. J. App. Agric. Apic. Res. 2013, 9, 81-90.