Does cover crop grazing damage soils and reduce crop yields?
2020
Blanco‐Canqui, Humberto | Drewnoski, Mary E. | MacDonald, Jim C. | Redfearn, Daren D. | Parsons, Jay | Lesoing, Gary W. | Williams, Tyler
Cover crop (CC) grazing can be a potential strategy to support livestock and crop production while enhancing soil ecosystem services, but research on this potential multi‐functionality of CCs is limited. We assessed 3‐yr cereal rye (Secale cereale L.) CC grazing impacts on soil compaction, structure, water infiltration, fertility, and crop yields on an on‐farm irrigated strip‐till continuous corn (Zea mays L.) silage experiment on a sandy loam with <1% slope in west‐central Nebraska. Treatments were: (a) non‐grazed CC, (b) grazed CC, and (c) no CC. Across the 3 yr, cattle grazed CCs at 5.9 AUM ha⁻¹ with grazing occurring over a 4‐mo period during winter and/or spring, depending on the year. We measured soil properties within 5 d after grazing ended in spring before tilling and planting corn. Cattle grazing resulted in a 92% decrease of CC biomass, compared with non‐grazed CCs. Grazing did not affect soil penetration resistance (compaction parameter), bulk density, aggregate stability, pH, and concentration of organic matter and nutrients except in the 2nd yr where it reduced cumulative infiltration by 80% and increased penetration resistance from 1.23 to 1.72 MPa but such increase was below root growth thresholds (<2 MPa). Cover crop grazing had no negative effect on corn silage yields although data were variable. Overall, CC grazing for 3 yr had small and variable effects on soils and crop yields, indicating that it can be a management option to support livestock production but more long‐term data from different tillage and cropping systems, and climates are needed to further understand CC grazing implications.
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