Evaluating Rotations of Cover Crops and Summer Annual Forages for Yield, Nutritional Value, Effect on Soil Nutrient Profile, and Economic Sustainability as Forage for Beef Cattle
In addition to protecting Iowa’s water quality and preserving valuable topsoil and nutrients, cover crops can provide an additional forage source to Iowa beef producers. While the long-term benefits of cover crops such as reducing soil erosion and improving soil organic matter are well documented, it can be difficult to put a dollar value on those returns on investment. Producers may be more inclined to use cover crops if they can realize a short-term benefit in addition to the long-term conservation benefits. One logical potential short-term benefit that could incentivize this practice is the utilization of cover crops as a forage resource to stretch the feed supply, extend grazing and increase carrying capacity. However, a more complete understanding is needed for utilization of alternative forages by beef cattle across the state.
Since 2012, Iowa has lost another 125,000 acres of permanent pasture while beef cow numbers have rebounded to just over 938,000 head, according to the 2017 Census of Agriculture. This data shows a continuing trend of beef cattle producers maintaining or increasing production on fewer and fewer acres of permanent pasture. If Iowa producers can use cover crop forages as beef cattle feed resources, cover crops will be more attractive as a practice with multiple benefits.
The objective of this study is to evaluate potential yield, nutritional value, effect on soil nutrient profile and economic sustainability of cover crops used in rotation with various summer annual forage species. This project will demonstrate and aid in development of best management practices of rotating winter cover crops and summer annuals to optimize forage production while improving soil and water quality.
To achieve these objectives, this study will:
- Evaluate nutrient content and potential yield of various cover crops and summer annuals used in rotation as conservation practices and forage resources for beef cattle. Forage samples will be taken to determine forage yield and nutritional value of the cover crops and the annual species.
- Determine soil nutrient loss when cover crops and annuals are mechanically harvested. Soil samples will be taken at the beginning of the study to establish a baseline for soil phosphorus, potassium, pH and organic matter. Nutrient content of forage samples will be used to calculate estimated nutrient removal with forage harvest.
- Demonstrate integration of winter cover crops in rotation with summer annuals to optimize forage production for beef cattle.
- Educate producers through extension and outreach efforts, sharing findings through a variety of formats and events.
In the first six months of the project, primary activities included seeding summer annuals at each of the three research farms and collecting samples of the summer annual forage to be analyzed for digestibility, nutrient content and yield. Samples were sent to Dairyland Labs for nutritional analysis and measurements taken to analyze for yield estimation. Annual crops were harvested, and the remaining stands terminated. Winter cover crops were then seeded at each of the three research farms in fall 2019. Those forages are still standing, and samples will be collected this spring to be analyzed for digestibility, nutrient content and yield. The warm season seed for the initial summer annual seeding was donated by Millborn Seed and Barenburg. Seed for the winter cover crop seeding was purchased from Millborn Seed.
Outreach during this period included presentations at the McNay Research Farm Field Day and the Neely Kinyon Farm Field Day.