Pastejo e adubação nitrogenada sobre os atributos físicos do solo em sistema de integração lavoura-pecuária

Grain farmers have seen integrated crop-livestock systems (ICLS) as an alternative of great interest by providing cattle food supply, as well as improvement of the phisical properties of soil. This study aimed at evaluating the effect of grazing and nitrogen levels on soil physical properties and on corn yield in an integrated crop-livestock farming. The experimental design was a randomized complete block design with a split plot arrangement of treatments and three replications per treatment; nitrogen doses were the main plots, and grazing presence or absence were the subplots. We applied four doses of nitrogen (0, 75, 150, and 225 kg ha(-1)) in soils grown with ryegrass (Lolium multiflorum Lam.) and oat (Avena sativa Lam.) during winter. After the grazing period, the area was planted with corn (Zea mays Lam.) within summer. Sheep grazing with stocking rate control and herbage mass maintenance using oats and ryegrasses did not change soil density, macro, micro and total porosity in a Bruno Latosol (Oxisol). Grazing in nitrogen-fertilized areas did not impair corn yield. Previous nitrogen fertilization in winter grazing, in amounts equal to or higher than 150 kg N ha(-1), ensures high corn yields in the absence of N applications.