Nitrogênio no feijoeiro em sistema de plantio direto sobre gramíneas

Abstract

An adequate supply of nitrogen is essential for high yield of common bean seeds; however, the responses to this nutrient in no-tillage systems can vary in function of the species and the amount of straw present. The aim of this research was to evaluate response of the common bean to N in no-tillage systems over maize, millet and Brachiaria brizantha crop residues. Three experiments were conducted, one for each gramineous species. The experimental design was a randomized block in a 5×2×2 factorial scheme, with five N doses (0, 30, 60, 90, 120 kg ha-1), in two distinct stadia during the vegetative development (3rd and 6th trifoliate leaf) and two common bean cultivars (IPR Juriti and Pérola), with four replications. The IPR Juriti produced a greater number of pods per plant and showed lower mass per 100 seeds than Pérola. It did not show variation in bean yield when the sidedressing N application was carried out in the 3rd or 6th trifoliate leaf stadia. Based on the obtained results, one concludes that the seed productivity of common beans increases linearly with N doses in a no-tillage system over maize residues.