Dryland cover crop soil health benefits are maintained with grazing in the U.S. High and Central Plains

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2021-06, Vol.313, p.107358, Article 107358
• Main Authors: Kelly, Courtland, Schipanski, Meagan E., Tucker, Angela, Trujillo, Wilma, Holman, Johnathon D., Obour, Augustine K., Johnson, S.K., Brummer, Joe E., Haag, Lucas, Fonte, Steven J.
• Format: Article
• Language: English
• Subjects: Aggregate stability; agriculture; arid lands; bulk density; Colorado; cover crop termination; cover crops; environment; fallow; income; Integrated crop-livestock systems; Kansas; livestock; Nebraska; no-tillage; on-farm research; profitability; soil aggregation; soil conservation; soil quality; soil water; summer; Summer fallow; Water use; wheat; Winter wheat
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2021.107358

•Short-term, on-farm grazed and un-grazed cover crop trials were established.•Cover crops increased soil aggregate stability compared to summer fallow.•Bulk density was similar between grazed cover crops and summer fallow.•Replacing summer fallow with cover crops reduced winter wheat yields.•Grazed cover crops did not reduce soil quality, and may diversify farm income. Cover crops are important for soil conservation efforts but can compete with cash crops for limited water in dryland agricultural systems. Grazing cover crops may provide additional income to improve the profitability of cover cropped systems, but the effect of grazing cover crops on soil health remains poorly understood in semi-arid regions. We conducted on-farm research to examine the short-term effects of grazed and un-grazed spring-planted cover crops compared to full summer fallow on soil health metrics and wheat yields across ten no-till, dryland producer fields over two years in eastern Colorado, western Kansas and western Nebraska, USA. Soils were evaluated at cover crop termination following two to three months of growth for differences in a suite of soil physical and chemical properties. Grazed and un-grazed cover crops increased soil aggregation relative to summer fallow by 30−50%. Surface bulk density (0−5 cm) decreased by 4% with un-grazed cover crops, while bulk density under grazed cover crop was similar to fallow. Soil moisture in the top180 cm depth was reduced by 4–22 % with cover crops, with the greatest water depletion occurring below 30 cm, and grazing did not appear to affect soil moisture compared to un-grazed cover crops. Both cover crop treatments reduced wheat yields by roughly 20 %. The short-term improvements to key soil health metrics with cover crops were largely maintained with grazing, indicating the potential for livestock integration as a management option to offset the short-term yield impacts of cover crop moisture use in water-limited environments.