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

View the project final report

• 2016 annual report

Commodities

• Agronomic: corn, rye
• Animals: bovine
• Animal Products: dairy

Practices

• Animal Production: winter forage
• Crop Production: catch crops, cover crops, no-till, nutrient cycling, conservation tillage
• Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research
• Farm Business Management: budgets/cost and returns
• Natural Resources/Environment: biodiversity, carbon sequestration
• Production Systems: integrated crop and livestock systems
• Soil Management: organic matter, nutrient mineralization, soil chemistry, soil microbiology, soil physics, soil quality/health

This project was successfully completed as planned. The project was conducted on five representative sites including four on-farm sites (Tecumseh, Firth, Mead, and North Platte, NE) and two research sites (Mead and North Platte, NE) across a precipitation gradient in Nebraska. At each site, we had at least three common treatments with three replications. Treatments included: 1) control (non-grazed/non-harvested cover crop), 2) grazed/harvested cover crop, and 3) no cover crop under continuous corn, corn-soybean and corn-soybean-wheat rotations under no-till management. Corn was harvested as silage. At one on-farm site (Firth), cover crop was harvested (not grazed). The size of each treatment plot varied to accommodate farming operations. The control and cover crop plots were fenced and the area outside with cover crops was grazed. Winter rye cover crop was used at most sites followed by oats and mixture of brassicas. Continuous corn as silage (most sites), corn-soybean at the Mead research site, and corn-soybean-wheat at the Tecumseh site were used. We worked with the producers who participated in the establishment of the experiment on their farms and managed cover crops. Each year, we measured subsequent grain yield and cover crop biomass for the cover crop treatments. We also measured soil structural and compaction parameters, water infiltration, and other soil properties. Our data showed no negative effect of grazing cover crops on soil compaction. Grazing and harvesting cover crops had mixed effects on water infiltration. They reduced water infiltration at some sites but not at others. Grazing and harvesting cover crops had no negative effect on soil aggregate stability, soil fertility, soil C concentration, and other chemical properties. Grazing and harvesting effects were highly site-specific (i.e., livestock management). We presented results at several field days. Average attendance of farmers was about 40  at each event. We trained a post doc and several undergraduate student researchers. We have been invited to give several regional and national talks because of the relevance of our project. We also disseminated results in field days and conferences. Overall, the results from this project indicate that cover crop grazing and harvesting have small or no effects on soils and crop yields in rainfed and irrigated systems although high cattle stocking rates may tend to negatively affect soils and crop yields.

Objectives

We focused on the following objectives:

1. Measurement of grain yield, cover crop biomass, and percent soil cover after grazing.
2. Assessment of soil structural, compaction, and water infiltration properties as affected by grazing cover crops.
3. Assessment of soil fertility properties.
4. Economic analysis.