Soil Amendments Affect the Release of P from Rock Phosphate and the Development and Yield of Okra

ABSTRACT Rock phosphate (RP) is being considered as a phosphorus (P) source for reversing soil fertility depletion in Sub-Saharan Africa. We conducted research to evaluate organic or inorganic materials to be combined with RP to enhance P availability. Field trials were conducted at the Institute of Agricultural Research and Training, Moor Plantation, Ibadan in 2001 and 2002 to evaluate the comparative effects of urea (U) and poultry manure (PM) on solubilization of rock phosphate and on the growth and yield of okra (Abelmoschus esculentus (L.) Moench). Okra growth and yield were significantly enhanced by the addition of the treatments. The combined use of RP with either PM and to a lesser degree U, significantly improved the growth and yield of okra compared to when the materials were used individually. Application of RP + U and RP + PM increased available soil P of between 112 and 115% and 144 and 153%, respectively, in both years.