Soil fertilization may be a sustainable strategy for the intensification of grazing, considering that the effects of cattle trampling that are deleterious for the soil physical quality do not affect the productivity and the sustainability of pasture production systems. The purpose of this study was to evaluate the effect of grazing at different intensities of N-fertilized pasture on the soil physical quality and impact on forage and root yield of Panicum maximum cv. IPR-86 Milênio. The experiment was conducted in Paranavaí -PR (23º 5' S, 52º 26' W; 460 m asl). The animal management consisted of rotational stocking at variable stocking rates. The amount of water retained in soil, resistance to root penetration and forage dry matter, green leaf and root production, were measured as biological response to soil physical conditions to assess the impact of grazing at different intensities on the soil physical quality. Nitrogen fertilization increased the production of forage dry matter and green leaves. The values of soil penetration resistance were lowest at the lowest grazing level in the area of animal tramping, between grass tussocks. In the tussock area, soil penetration resistance was lower in the less intense treatments than in the others, in the layers 0.2-0.3 and 0.3-0.4 m only. The increase in soil penetration resistance reduced root production of Panicum maximum Jacq.cv. IPR-86 Milênio. Root production was highest when the values of soil penetration resistance were below 1 MPa.
Pasture; water content; animal trampling; soil compaction; Panicum maximum - IPR-86 Milênio
