Influência do sistema integrado de produção agropecuária no solo e na produtividade de soja e braquiária

Abstract

The presence of animals in farming areas can affect soil physical structures depending on grazing intensity. This study aimed to evaluate soil physical attributes, as well as soybean and brachiaria yield, under no-tillage, in an integrated crop-livestock system. Treatments were arranged in a complete randomized blocks design, with three replications, and consisted of different grazing heights (0.25 m, 0.35 m and 0.45 m) and a no-grazing area. The shoot and root dry biomass of soybean and brachiaria and soybean yield were evaluated. Soil samples were collected from 0-5 cm, 5-10 cm and 10-20 cm depth layers and the following soil physical attributes were determined: bulk density, total porosity, macroporosity, microporosity, penetration resistance and mean weight diameter of aggregates. Grazing intensities did not affect soil bulk density in any of the analyzed layers. There was a reduction in total porosity after the second grazing cycle, in the 0-5 cm layer. The mean weight diameter of aggregates was lower in grazed areas, in the 0-5 cm and 10-20 cm layers, and an increase in the penetration mechanical resistance was observed in all layers, especially for the 0.25 m height grazing treatment. The total dry biomass (soybean + brachiaria) and shoot dry biomass of brachiaria were lower in grazed areas. However, the soybean yield was not affected by the different grazing cycles.