Response of cowpea to phosphorus on an Oxisol with special reference to dry matter production and mineral ion contents

Abstract

The objective of this investigation was to evaluate the effects of P fertilization on growth, yield and nutrient uptake patterns in cowpea. Phosphorous application significantly increased growth, yield and yield components. The critical soil-applied P levels was 160 mg kg-1 of soil for seed yield and 142-150 mg P kg-1 of soil for yield components. The critical level of soil P extracted for seed yield was 40 mg kg-1 of soil and the plant tissue critical level was 0.13% at harvest. Analyses of nutrient distributions in different plant parts showed that cowpea roots retained maximum Fe and minimum K and Ca. Tops retained maximum Ca, almost 50% of P, K and Mg and 65% of Mn; large amounts of P, K, Zn and Cu were translocated to seeds. Pot husks contained a high level of Mg and Cu. Phosphorous fertilization decreased the concentrations of K, Zn and Cu in plant tops. Magnesium concentration was increased with P fertilization; Ca and Fe concentrations were unaffected.