Biomass yields, soil cover, content and accumulation of nutrients of some green manure legumes grown under conditions of north of Minas Gerais, Brazil.

Abstract

The potential of green manure crops as conservation practice play an important role in soil quality and sustainability of agricultural systems. This field experiment was conducted in 2009 season to evaluate the performance of different green manures cultivated under Minas Gerais conditions, southeast Brazil. The treatments, in randomized blocks with three replications, were: Spontaneous vegetation (control), Sunhemp (Crotalaria juncea), Pigeonpea (Cajanus cajan), Velvetbeans (Mucuna aterrima, Mucuna pruriens, Mucuna deeringiana), Lablab (Lablab purpureus), Jackbean (Canavalia ensiformis), Cowpea (Vigna unguiculata) and mixture (all treatments). From the green manures screened, M. pruriens and the spontaneous vegetation presented the highest soil covering potential. The largest productions of fresh shoot biomass were recorded from the spontaneous vegetation, C. juncea and C. ensiformis. C. juncea and spontaneous vegetation also had the largest production of dry shoot biomass. The green manures presenting more nutrients in the shoot were the C. juncea, with higher contents of N, P, Ca, Mg and B, and spontaneous vegetation with the highest contents of K and Mg. In conclusion, the use of these green manures is promising and an appropriate technology for the reduction of chemical fertilizer use. Key words: Agroecology, Canavalia ensiformis, crop rotation, family farming, green manures.