Atributos físicos de um Latossolo Vermelho distroférrico em sistema de integração lavoura-pecuária

The trampling of grazing animals can compact the surface layers and affect the physical quality of soils in crop-livestock systems (ICL). The hypothesis of this study is that increased trampling from animal grazing of oats and ryegrass reduces the soil physical quality of an Oxisol under no-tillage with ICL. The purpose of this study was to quantify bulk density (Bd), air-filled porosity (ea), soil air permeability (Ka), soil resistance to penetration (SR) and estimate an index of pore continuity from the linear relationships between ea and Ka. In the experimental area in Campo Mourao - PR, with ICL under no-tillage, soybean or corn was grown as cash crops and oat plus ryegrass as forage for grazing. The treatments were four grazing heights (7, 14, 21, and 28 cm) and an ungrazed control. From each treatment, 20 undisturbed samples were collected from the layers 0-7.5 and 7.5-15 cm. There were no significant differences in Bd, ea and Ka between the control and the grazed treatments. In the 0-7.5 cm layer, the mean Ka values were similar between treatments. After eight years of ICL, the BD, ea and Ka did not confirm the hypothesis that intensification of grazing reduces the soil physical quality. However, SR showed differences between the control and grazed treatments, with restrictive SR values down to a depth of 15 cm, suggesting that increasing the grazing intensity reduces the soil physical quality.