The objective of this experiment was to evaluate green manures and their effects in the sugarcane yield using no-tillage system (SPD). The experiment was carried out at Campos dos Goytacazes, Rio de Janeiro State, from december/2003 to july/2005. The experimental design was a randomized complete block with four replications. The treatments were jack bean (Canavalia ensiformis), velvet bean (Mucuna aterrimum) and sun hemp (Crotalaria juncea) under no-tillage and spontaneous vegetation in conventional tillage (PC) (control). The sunhemp 35 days after emergency (DAE) showed higher rate of soil cover 87% and 92 DAE produced 17.852 kg ha-1 of dry matter, 41%, 78% and 407% superior to jack bean, velvet bean and spontaneous vegetation, respectively, besides overcoming them in accumulation of K, Mg, S, Zn and Fe. Jack bean and velvet bean showed the highest content of N in the aerial part than other covering plants. Jack bean showed higher contents of P and Ca than sun hemp and velvet bean. The spontaneous vegetation showed the highest content of K in aerial part in relation to the cover plants. The legumes accumulated higher amounts of N and Cu than the spontaneous vegetation. Sun hemp and the jack bean accumulated 66% more of P in the aerial part than velvet bean. The SPD using green manures contributed significantly to sugarcane, yield that was 135.863 kg ha-1, being 37% superior to PC with the spontaneous vegetation.
Crotalaria juncea; Saccharum oficinalis; sustainable agriculture
