Results from a three-year study in rainfed and irrigated no-till cropping systems in Nebraska suggest that moderate cattle grazing of cover crops may not negatively impact soil properties and crop production.
Cover crop grazing compacted soil in some years but the increase in the compaction level was small and below the threshold levels that can restrict root and crop growth. Grazing of cover crop also had small or no effects on wet soil aggregate stability, water infiltration, and concentrations of organic matter and essential nutrients, suggesting that cover crop grazing may not adversely affect soil structural, hydrological, and fertility properties.
Cover crop grazing at the irrigated site tended to reduce corn silage yields, but differences were not statistically significant. At the rainfed site, crop yields did not differ with cover crop grazing. The trend for decreased corn yields with cover crop grazing at the irrigated site may have been due to the greater cover crop grazing intensity at this site compared with the rainfed site. Similarly, cover crop harvesting had small and inconsistent effects on soils and crop yields.
Our study results also indicated that both ungrazed and harvested cover crop improved soil properties in some years but had no effects on crop yields. Use of brassicas mixed with grass cover crop appears to improve soil properties such as water infiltration more than winter rye alone in the short term. Tap-roots can create large biopores to rapidly improve water capture and infiltration.
Results also indicate that while the use of cover crop as forage appears not to have large negative effect on soils and crops, they suggest that the early response to cover crop grazing can be highly site-specific. For example, cover crop grazing reduced water infiltration and tended to reduce crop yield trends at the irrigated but not at the rainfed site. This could be attributed to differences in grazing intensity.
Findings from this study suggest that integrating cover crop with livestock production can be an option to provide high quality forage and enhance farm profitability in the Midwest, although additional long-term studies are needed to establish the threshold levels of cover crop grazing.
In conclusion, moderate cover crop grazing under no-till management can have small or no effects on soil properties and crop yields in the short term.
Acknowledgment
This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2015-38640-23781 through the North Central Region SARE program under project number LNC15-366. USDA is an equal opportunity employer and service provider. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
