Cover crop grazing length impacts on soil health and crop productivity in US Coastal Plain soils

Introducing integrated crop-livestock systems into row crop production promotes income diversification and potential soil health benefits through cover crop grazing on degraded soils of the southeastern United States, but effects of these practices on crop yields and soil health in Coastal Plain soils are not well established. A 4-year study was performed to evaluate the effects of grazing a multi-species winter cover crop on soil health and crop yields under mid-February, mid-March, and mid-April cattle removal dates and a non-grazed control within an annual cotton (Gossypium hirsutum L.) and peanut crop rotation (Arachis hypogaea L.). Chemical soil health indicators (soil organic carbon and permanganate oxidizable carbon), physical soil health indicators (water-stable aggregates and penetration resistance), biological soil health indicators (microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi colonization), crop yield, and cover crop biomass were evaluated. Cover crop biomass at termination was reduced by 3660, 5250, and 5610 kg ha⁻¹ for the mid-February, mid-March, and mid-April cattle removal treatments compared to the non-grazed control. No grazing treatment effects were observed for biological soil properties. Soil organic carbon was higher in the non-grazed treatment than the mid-April grazing treatment across 0- to 30-cm depth. Penetration resistance across 0- to 50-cm depth and water-stable aggregates at the 0- to 30-cm depth were both negatively impacted by increased grazing period lengths. Results from this study suggest that longer cover crop grazing periods have little effect on biological and chemical soil health indicators in the short term but can negatively impact some physical soil health indicators.