Abstract
Phosphorus and N fertilizer level effects on nodulation, dry matter yield, dinitrogen fixation (as measured by the 15N technique), N and P tissue content and seed yield of three common dry bean (Phaseolus vulgaris) cultivars were investigated in a field experiment. The two levels of P were: no P applied and P applied at a rate of 150 kg P ha-1; the two N fertilizer levels were: 10 kg N ha-1 and 100 kg N ha-1. Application of P increased nodulation, dry matter yield, P uptake, tissue N yield, dinitrogen fixation and seed yield of the three bean cultivars at both N levels. A high dose of N severely reduced nodulation only where P was not applied but severely reduced dinitrogen fixation at both P levels. Where P was applied cultivars fixed comparable quantities of dinitrogen. At the low level of N where no P was applied, however, one cultivar (Rose coco) nodulated well early in the growth stages and fixed substantial dinitrogen.
