No-tillage on corn production in rainfed agriculture in Northeast Brazil/Semeadura direta na producao do milho em agricultura de sequeiro na regiao Nordeste do Brasil

When efficiently introduced, no-tillage system benefices soil and crops. In Brazil, no-tillage studies are concentrated in South and Center-west regions, being necessary information about it in Northeast region. The aim of this study was to evaluate the no-tillage influence on maize yield under rainfed agriculture in Northeast Brazil, in an experiment conducted during seven years. The crops of maize (Zea mays) and pigeon pea (Cajanus cajan) were used in three soil management systems: maize in conventional tillage (CC), maize in no-tillage (SD), maize in no-tillage plus pigeon pea sowed in the interrow (SG), with presence and absence of mineral N, P and K fertilization. Soil samples were collected at the beginning and the end of the experiment to determine soil bulk density, soil particle density, total porosity, dry and wet mean weight aggregate diameters and aggregate stability index. It was also quantified soil cover rate and maize yield. The soil porosity and aggregate stability were lower after the study period. Soil coverage increased significantly, about 96 % of the area under SD and SG systems, early in the culture development. Mineral fertilization and no-tillage systems highly influenced the maize yield. The rainfall was the factor that caused greater variability on the results of this study. Key words: soil cover, soil management systems, no tillage, conventional tillage. Quando implantado de modo eficiente, a semeadura direta beneficia o solo e as culturas. No Brasil, a maioria dos estudos com plantio direto concentra-se no Sul e no Centro-Oeste, carecendo de informacoes sobre esse sistema de manejo do solo no ambiente da regiao Nordeste. O objetivo deste trabalho foi avaliar a influencia da semeadura direta na produtividade do milho em agricultura de sequeiro na regiao Nordeste do Brasil, em um experimento conduzido em Alagoinha-PB durante sete anos. As culturas do milho (Zea mays) e do guandu (Cajanus cajan) foram implantadas em tres sistemas de manejo: milho em cultivo convencional (CC), milho em semeadura direta (SD), milho em semeadura direta com guandu intercalar (SG), na presenca e ausencia de adubacao com N, P e K. As amostras de solo foram coletadas no inicio e no final do experimento, sendo determinados a densidade do solo e de particulas, a porosidade total, o diametro medio ponderado de agregados secos e umidos e o indice de estabilidade de agregados. Tambem foram quantificadas a percentagem de cobertura do solo e a produtividade de