Does Grazing or Harvesting of Cover Crops Affect Soils and Crop Production? Assessment in Different Soil Types and Management Scenarios.

Cattle grazing of cover crops (CC) may fit the emerging integrated crop-livestock production systems, but its implications on soils and crop yields have not been widely researched. While many CC species can be a high quality source of feed for cattle, some people are concerned that grazing/harvesting CCs may adversely affect soil processes and properties (i.e., compaction, water infiltration, macroporosity) and concomitantly reduce soil productivity. Thus, tradeoffs between using CCs solely for soil cover and using them for animal feed must be comprehensively assessed. Our interdisciplinary and farmer-oriented ongoing research project, which started in fall 2015, is assessing: 1) impacts of grazing/ harvesting of CCs on soil physical, chemical, and biological properties, soil fertility, water and wind erosion, grain yield, and CC biomass across various farmers’ fields and research sites in Nebraska. Treatments include: 1) non-grazed/non-harvested CC 2) grazed/harvested CC, and 3) no CC under continuous corn, corn-soybean and corn-soybean-wheat rotations with three replications. Winter rye CC was used at three sites, oats at one site, and mixture of brassicas and rye at one site. Continuous corn was used at three sites and corn-soybean at two sites. The two-year results showed no negative effect of CC grazing on main crop yields. Soil compaction did not generally change with grazing. Mixture of brassicas and rye increased water infiltration and improved soil structure (soil aggregate stability). At some sites, grazing CC reduced water infiltration in spring but negative effects were not significant in summer. Wind erosion potential (dry soil aggregate stability) decreased at most sites under CCs compared with control (no CC), indicating that CCs can reduce wind erosion. Grazing CC did not affect soil fertility. Overall, grazing CC had no large negative effect on soil properties in the short term. More results will be presented at the meetings.