Consórcios de espécies de cobertura de solo para adubação verde antecedendo ao cultivo de milho e repolho sob manejo orgânico

Abstract

Four plant species, intercropped or not, were evaluates in the State of Rio de Janeiro for Green manuring and soil covering prior to corn or cabbage crops. Such crops were submitted to a no-tillage and organic farming system. The study relating to corn was carried out in Baixada Fluminense (Seropédica) at 33 m above sea level, whereas the cabbage experiment was the located in the South-Central Region (Paty do Alferes) at 680m. In bony experiments a randomized block design was employed with 12 treatments and four replicates. The species lazed for soil covering were: Crotalaria juncea (C), sorghum Sorghum bicolor (S), sunflower Heliantus annus (G) and castor bean Ricinus communis (M). Treatments involving such soil covering species corresponded to their monocrops ad the following intercrops: C+G, C+S, C+M, C+G+S, C+S+M and C+G+S+M. The control treatment consisted of fallow plots whove spontaneous vegetations was cut down on the day subsequent corn and cabbage were planted. In Baixada Fluminense, the previous intercrops favored epigeous edafic fauna diversity compared to fallow, either during vegetative cycle or after cutting except for castor bean monocrop, all treatments led to reduced need reinfestation in comparison to fallow plots. Corn yield (immature ears) was higher after monocrops of the soil covering species and also after fallow. Crotalaria showed in outstanding potential as green manure considering that organic suplementar corn fertilizing were proceeded only in plots previously cultivated to such legume species. The greatest cumulative e amount of above-ground biomass resulted from crotalaria monocrop probably contributing to a superior corn yield. In the South-Central field experiment the highest values for biomass productin were again obtained from crotalaria monocrop, its intercrops with each of the other soil covering species (C+G, C+S and C+M), and the triple intercrop with sorghum plus castor bean (C+S+M). Decomposition rates for the cut down plant residues in situ differed between intercrops and monocrops. Cabbage yield was as cell favoured by previous crotalaria and its intercrops, with exception of the intercrop in which all four plant species participated. Results have demonstrated the adequacy of crotalaria for rotational system with commercial crops under organic management. The experiments otherwise indicated that combining the legume with other soil covering species may lead to additional advantages in terms of crop residues persistence on soil surface and edáfica fauna stimulation.