The use of legumes in pre-cultivation on the common bean has the possibility of providing atmospheric N to the soil, making it available to this crop, and may cover part of its N demand and increase grain yield. The objective of present study was to evaluate the effect of hyacinth bean and jack bean as green manures on the production of common bean grown in two seasons. Cover crops were evaluated for fixed N 2 , dry matter yield, nitrogen (N) and carbon (C) concentrations, C:N ratio and N accumulation in the shoot. The jack bean accumulated higher biomass and more total N than hyacinth bean and spontaneous vegetation (control). However, both legume species, when used as green manure, resulted in an increase in the N concentration of common bean. Compared to the spontaneous vegetation, hyacinth bean residue increased yield of common bean by 32% and jack bean residue increased the bean yield by 46%. These yields were recorded when common bean was cultivated a few weeks after residues incorporation into the soil and about seven months later, thus showing a flexibility to family farmers for making their decisions on the best cropping season.

Aims:The objective of this study was to evaluate the efficiency of nitrogen utilization by corn cultivars for the production of green ears. Study Design: Treatments were constituted by the combination of two nitrogen doses (0 and 90 kg ha -1 N) and three corn cultivars (Cruzeta, Truck and AG 1051). The experimental design was the randomized block design, in a 2 x 3 factor scheme, with five replications.