Determination of phosphorus requirements of cowpea (Vigna unguiculata) in the acid soils of southeastern Nigeria using sorption isotherms
Global Journal of Agricultural Sciences 4(2): 135-138
The P requirement of cowpea at 2 locations in southeastern Nigeria (Bende and Umudike) was estimated using sorption isotherms. The method involved the equilibration of 3 g of soil obtained from both locations in 30 ml of 0.01 M CaCl2 containing various levels of P at room temperature for 5 days. From the P sorption curves constructed, P rates required to give 0.0, 0.1, 0.2, 0.3, 0.4 or 0.5 micro g/g were calibrated.