Effects of Phosphorus and Zinc on Maize and Cowpea Grown on Alfisols in Southern Nigeria
Trials were conducted at three locations on Alfisols in southwestern Nigeria to study the optimum phosphorus - zinc balance in the soil for field grown maize (Zea mays L.) and cowpea (Vigna unguiculata s.sp. ungzciculata L. Walp). The incidence of P induced Zn deficiency in maize was observed to be more probable in the sandy soils of the savanna zone than in the sandy loam soils of the forest zone. Correcting P deficiency without correcting Zn deficiency resulted in lower maize yields. In soils with Bray-1 P test of >7.0 ppm and 0.1N HCL extractable Zn of G 1.0 ppm, further addition of P. was observed to induce Zn deficiency in maize. Cowpea was less sensitive to either the deficiencies of P and Zn or to the incidence of P induced Zn deficiency.