Response of Maize Planted after Two Legumes to Four Rates of Phosphate Rock

A field experiment was conducted to study the combined effect of legume growth (in terms of agronomic P use efficiency from Phosphate rock (PR) and sources of nitrogen (N) from legumes and subsequent organic matter additions (green manure incorporation) on the growth and yield of maize. Four rates of PR (0, 40, 50 and 60 kg ha-1 P) were applied to two legume types: mucuna (Mucuna pruriens) and cowpea (Vigna unguiculata) and incorporated before sowing maize in a randomised complete block design replicated three times at the Teaching and Research farm of the Federal University of Agriculture, Abeokuta, Nigeria. Mucuna gave a significantly (p<0.05) higher percent N and dry weight (kg ha-1) compared to cowpea. The interaction of cowpea × 40 kg ha-1 PR gave a significantly higher value in Agronomic efficiency of applied Phosphorus (AEP) and Partial factor productivity of Phosphorus (PFPP), respectively. The increase in the AEP and PFPP by cowpea in the interactions could be that cowpea dissolved phosphorus from rock Phosphorus (P) better compared to mucuna by the combination of P release into soil solution following the mineralisation of organic P additions via cowpea. The interaction of mucuna × 50 kg ha-1 rock P significantly increased fresh cob weight of maize. Sustainable maize production can be achieved with combination of rock phosphate at 50 kg ha-1 and mucuna.