Effect of Phosphorus Fertilizer Application on the Yield of Component Crops in Cassava/Maize/Egusi Mixture on Alfisols in Nigeria.

Abstract

The scarcity and high costs of fertilizers which characterize the deregulating fertilizer market in Nigeria have engendered the search for alternative nutrient sources. Phosphate rock-fortified organo-mineral fertilizer (OMF), ground rock phosphate (GRP) and single superphosphate (SSP) were evaluated as P sources for cassava/maize/egusi mixtures at IkereEkiti and Omuo-Ekiti, Ekiti State, Nigeria. P was applied at 0, 26 and 52 kg P ha-1 in 2001- 2002 to cassava, maize and egusi mixed at 10,000, 20,000 and 20,000 plants ha-1 respectively. In 2002-2003, maize was in the mixture at 20,000, 25,000 and 35,555 ha-1 while P was applied at 0, 26 kg ha-1. The residual effects of applied P were measured in 2003-2004. P application significantly (P<0.05) increased the yields of component crops and 26 kg P ha-1 was the optimum for the P sources at the two locations. The increase in maize population significantly decreased maize and egusi yields but did not affect cassava tuber yield. GRP application gave highest maize yield at all maize populations and the highest or similar egusi and cassava yields compared to SSP and OMF in 2002-2003. The P sources showed significant residual effects on the mixture crops but the yields decreased as maize population increased. GRP had the highest residual effects in the two locations. Cropping decreased soil pH, available P and exchangeable Ca and Mg but the P sources increased soil pH and available P. The direct application and residual effects on crop yields and soil nutrients show the potentials of GRP and OMF as substitutes for SSP in cassava/maize/egusi mixtures.