Soil physical properties under different cattle stocking rates on Mollisols in the Buenos Aires Province, Argentina

This study evaluated the impact of different cattle stocking rates on different soil physical properties in different soils in an integrated livestock no-till agricultural system. We evaluated three stocking rates (0 animal unit ha−1, moderate: 160 animal unit ha−1, and heavy: 320 animal unit ha−1) on three soil textures (loamy sand, sandy loam and sandy clay). We also evaluated sorghum's performance after the cattle trampling in a crop sequence including winter rye + hairy vetch/sorghum. The representative soil in the area is a fine-loamy, mixed and thermic Entic Haplustoll with variable clay + silt (30 to 40 g kg−1 soil). Only bulk density showed interaction between texture and stocking rate factors. The control and moderate stocking rates showed lower bulk density (1.35 Mg m−3) than the heavy grazed treatment (1.43 Mg m−3) in the loamy sand soil. No differences between moderate and heavy treatments were found in other soil indicators. Layers of 0-5 and 5-10 cm proved to offer a higher mechanical resistance that the control (39% and 30%, respectively). Hydraulic conductivity and macroporosity (>100 μm) showed a reduction close to 20% in both indicators due to cattle trampling. Sorghum crop showed no differences in plant rate emergence, biomass and grain yield. Results of this investigation indicate that grazing and animal trampling produced no significant effect on the variation of physical properties over the different soil texture, neither any impact on the emergence and development of sorghum.