Physical Soil Quality In Grazed Pasture: Mixed Versus Single Species.

Grazing livestock systems affect soil quality. Different grazing systems may have different effects on the soil. In a specific area, one grazing system may improve, while another deteriorates, soil quality. The objective of this study was to measure and compare physical soil quality indicators with single (cattle) and multispecies (cattle and sheep) grazing. A three-year experiment was established at the WVU Reedsville Experimental Farm on a permanent pasture. Every year, single and multispecies summer grazing started on May 1, with stockpile grazing starting after August 1, and winter grazing (cattle only) initiated in early November. The following variables were measured before and after summer grazing, and after winter grazing: soil organic matter and bulk density (0-5 cm), aggregate stability (0-5 cm), penetration resistance (0-25 cm), and saturated soil surface hydraulic conductivity. In general, the single species grazing treatment exhibited higher SOM, but this difference was not statistically significant. Soil bulk density, penetration resistance, and dry and wet aggregate stability were impacted by single and mixed species summer grazing, but again the observed differences were not statistically significant. At the beginning of the experiment no difference in saturated hydraulic conductivity due to single or mixed grazing systems was found, but by year 3 the single species grazing treatment exhibited significantly higher saturated hydraulic conductivity. There was a trend suggesting that the two different grazing systems affected the soil differently. Additional research, over a longer period of time, would be needed to better assess the impact of the treatments on these grassland soil ecosystems. The data indicate that, over time, grazing animal management decisions might impact the sustainability of the soil-grassland interface, particularly surface soil physical and hydrologic properties.