Response of irrigated common beans to nitrogen and potassium

Abstract

A field experiment was conducted during 1991 and 1992 to determine the effects of N and K fertilization on yield and yield components of common beans cultivated under irrigation by a center pivot system. The experiments were carried out in a farmer's field in the municipality of Jussara, GO, Brazil. The soil of the experimental site was an Oxisol with sandy texture. The treatments consited of 0, 40, 80, and 120 kg K₂O ha^-1 and 0-30-60 and 90 kg N ha^-1. In addition, there were two methods of potassium application, i.e. 100% applied at planting, and 50% applied at planting + 50% as top dressing together with N application. Nitrogen was applied 1/3 at planting and 2/3 as top dressing. Production of dry matter, concentration and accumulation of N in the tops and number of pods per plant increased with increasing levels of N. Grain yield response was quadratic in relation to N treatments and and maximum yield was obtained at 72 kg N ha^-1. Potassium fertilization had significantly negative effect on 100 grain weight.