Yield Response of Cowpea to Phosphorus Fertilizer Application

Abstract

Phosphorus fertilizer application plays a major role in nodulation and grain yield production of cowpea. However, phosphorus is a major limiting nutrient in soils in Ghana. Selection of cowpea varieties that produce good biomass and grain yield under low soil phosphorus or those with high phosphorus response efficiency could be a cost-effective approach in solving the phosphorus deficiency problem in Ghana. This study was therefore conducted to determine the appropriate levels of phosphorus fertilizer application for improved nodulation and grain yield of four cowpea varieties. Two-season experiments were conducted to evaluate the influence of phosphorus (P) fertilizer on growth, nodulation, biomass and grain yield in cowpea. Each of the two experiments comprised of 16 treatment combinations of 4 cowpea varieties and 4 levels of P2O5 application laid out in 4×4 factorial experiments in RCBD with three replications. The cowpea varieties were IT × P 148, Valenga, Bengkpla and DPC. The levels of P were 0, 20, 40 and 60 kg P2O5 ha−1. The study revealed that varieties DPC and Valenga performed relatively better with respect to grain yield, shoot and root dry biomass production, nodulation, nodule dry biomass production, plant height, number of branches produced and number of days to 50% flowering across all levels of phosphorus fertilizer application. The study further established that P level of 60 kgha−1 also produced significantly higher quantities of yield and vegetative parameters such as grain yield, 100-grain weight, number of pods and branches, shoot and root dry biomass, nodulation and nodule dry biomass, as compared to P levels of 0 kgha−1, 20 kgha−1 and 40 kgha−1. Phosphorus fertilizer application level of 60 kgha−1 should be used for increased grain and biomass yield. For the purpose of producing grains for human consumption and leguminous fodder crops for feeding livestock, it is recommended that varieties DPC and Valenga should be cultivated for increased yield.