Evaluation of Cover Crops for Grazing Systems

By Brad Heins and Jim Paulson, U of MN 

We identified cover crop species that needed investigation to establish cultural practices and nutritional value if utilized for forage. To become more profitable, dairy producers may need forages that can fill slumps in grazing systems, extend the grazing season and provide emergency cover and forage. Dairy producers are looking for ways to integrate cover crops into their cropping and pasture systems. We designed a demonstration study that would determine the forage potential and nutritional value of selected cover crop species and mixtures on Minnesota farms.

The following cover crop species were evaluated: Annual ryegrass, Berseem clover, Buckwheat, BMR sorghum-sudangrass, Crimson clover, Fodder beets, Forage oats, Forage peas, Grazing corn, Kale, Lentils, Pearl millet, Phacelia, Rox Cane, Sorghum-sudangrass, Soybeans, Sugar beet, Sunn hemp, Teff, and Turnip.

We planted replicated plots of cover crops at the West Central Research Center and on a dairy farm in Lanesboro, MN. The plots were planted June 24, 2015 and harvested August 20. A plot flail harvester was used to harvest the cover crops and dry matter yields were determined. A sample of harvested forage was retained from selected plots for dry matter determination and forage quality analysis. Forage quality analysis was conducted by Dairyland Laboratories, St. Cloud, MN. 

Forage analysis differed among species and crude protein ranged from a high of 24.0% for fodder beet tops to a low of 10.9% for BMR sorghum-sudangrass. Total Digestible Nutrients (TDN) was highest for sugar beets and turnip tops of 68.6% and 67.8% respectively; however, TDN was the lowest for forage peas and grazing corn at 45.5% and 48.4%, respectively. Taller plants such as BMR sorghum-sudangrass and Rox Orange cane yielded greater amounts of dry matter per acre. The lush turnip and kale tops excelled in forage quality, but were lower in dry matter yield per acre. From these data, we can better recommend combinations of species to fit certain cover crop and grazing scenarios. This project was funded by a grant from the Midwest Forage Association.