Grazing cover crops: How does it influence soils and crops?

Grazing cover crops (CCs) can potentially generate economic benefits, but how this practice affects soils and crop production compared with non-grazed CCs is not well understood. We reviewed all published literature up to June 30, 2023, on grazing CCs to evaluate how this practice impacts soils and crop production and discuss potential factors that may influence grazing CC effects. The emerging literature indicates that 18%–92% of CC biomass was removed when grazed. Grazing CCs increased soil bulk density and penetration resistance (compaction indicators) in 54% of cases (six of 11 studies). However, the increase in soil compaction as measured by penetration resistance generally remained below the root-growth threshold level (<2 MPa). Grazing CCs had small and mixed effects on soil C concentration, wet aggregate stability, water infiltration, water retention, and soil microbial biomass. In addition, grazing did not affect subsequent crop yields in 61% of cases (eight of 13 studies) or had variable effects. Grazing at high stocking rates or when soils are wet can result in soil compaction and potentially reduce subsequent crop yields. Additional long-term (>5 years) data are needed to better discern CC grazing implications for different climates, stocking rates, soil types, CC grazing infrastructure, and CC management practices. Particularly, data on CC grazing from water-limited regions (i.e., semi-arid regions) are scant. Success with CCs in water-limited regions depends on timely precipitation input unless irrigated. Overall, grazing of CCs under proper management has small or no effects on soils and crop yields.