Cover crops phytomass and nutrient accumulation and castor bean grown in succession under no-tillage system/Producao de fitomassa e acumulo de nutrientes por plantas de cobertura e cultivo da mamona em sucessao no sistema plantio direto

The objective of this study was to evaluate aboveground matter production and nutrients accumulation by sunnhemp (Crotalaria juncea L.) and pearl millet (Pennisetum glaucum (L.) R. Brown), in sole crop and intercropped, and the effect of straw mulch mechanical management on castor bean (Ricinus communis L.) performance, in notillage system establishment. The experiment was carried out on a Rhodic Kandiudox, in Botucatu, SP, Brazil (22058'S, 48023 W and 765m above sea level). A randomized block design, in a splitplot scheme, with four replications, was used. The plots were composed by three cover crops: sunnhemp--cv. 'IAC-KR1'; pearl millet--cv. 'BN 2'; and intercropping--sunnhemp + pearl millet. The subplots were composed by absence or presence of straw mulch mechanical management, by horizontal crusher use, 20 days after chemical management. Pearl millet sole crop produced greater dry matter and showed higher K, Mg, and S concentration in aboveground, 75 days after emergence, while N and Ca concentration were higher in sunnhemp. Pearl millet sole crop accumulated greater amounts of N, P, K, Mg, and S, in aboveground, while sunnhemp accumulated elevated amount of Ca. Castor bean grain yield was higher in succession to sunnhemp + pearl millet intercropping and in the absence of straw mulch mechanical management.