Phosphorus and cultivar effects on nodulation, growth, dinitrogen fixation and yield of cowpea (Vigna unguiculata)

Abstract

In field experiments at Katumani in 1982, cowpea cv. Katumani 80 and Vita 4 were grown in chromic luvisol soils and treated with 15N-labelled ammonium sulphate at 20 kg N/ha, with or without 70 kg P/ha. Differences in nodule DW, DM yield, P uptake and tissue N yield were detected between cv. at maturity, but P rate had no effect. Av. seed yields of Katumani 80 and Vita 4 were 1.16 and 1.05 t/ha, resp., and were unaffected by P rate.