Phosphorus requirement of a maize-cowpea sequential cropping on a paleudult

Abstract

A field experiment was conducted for 6 growing seasons on a Paleudult to assess the influence of P rate and frequency on crop yield and P fractions in a maize-cowpea sequential cropping system. Although cropping depleted soil organic P by up to 42.1% over the cropping seasons perhaps through mineralisation, the major portion of added P and mineralised P were not utilised by the crops. Transformations were probably more to the insoluble Fe-P than Al.P. Cumulative recovery of P in maize and cowpea was never above 75% at a single application of 30kg P ha⁻¹ over a period of 6 seasons while cumulative recovery of annually applied P ranged from 17.1 to 31.8% over the same period. Lower values were recorded for seasonally applied P plots. Annual application of P at 30kg ha⁻¹ kept the available P above the critical level and maintained maize and cowpea yields at near maximum over the cropping periods.