RESPONSE OF IRRIGATED COMMON BEANS TO NIT ROGEN AND POTASSIUM

A field experiment was conducted during 1991 and 1992 to determine the effects of N and K fertilization on yield and yield components of com mon beans cultivated under irrigation by a center pivot system. The ex periments were carried out in a farmer's field in the municipality of Jussara, GO, Brazil. The soil of the experimental site was an Oxisol w ith sandy texture. The treatments consited of 0, 40, 80, and 120 kg K2 O ha(-1) and 0-30-60 and 90 kg N ha(-1). In addition, there were two m ethods of potassium application, i.e. 100% applied at planting, and 50 % applied at planting + 50% as top dressing together with N applicatio n. Nitrogen was applied 1/3 at planting and 2/3 as top dressing. Produ ction of dry matter, concentration and accumulation of N in the tops a nd number of pods per plant increased with increasing levels of N. Gra in yield response was quadratic in relation to N treatments and and ma ximum yield was obtained at 72 kg N ha-1. Potassium fertilization had significantly negative effect on 100 grain weight.