Winter Pea, Crimson Clover, and Hairy Vetch Planted in Mixture with Small Grains in the Southeast United States
Legume and small grain cover crop mixtures may simultaneously fix N and suppress weeds. Studies were conducted from 2015 to 2017 in Maryland and North Carolina to compare winter pea (Pisum sativum L. to crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosa Roth) for cover crop use in mixture with small grains. Five winter pea genotypes, one crimson clover cultivar, and one hairy vetch cultivar were screened in mixture with barley (Hordeum vulgare) oats (Avena sativa) and wheat (Triticum aestivum) Cold injury of the pea genotypes in Maryland severely impacted pea biomass. Peas were able to recover from cold injury in North Carolina. A robustly growing small grain aided in legume cold tolerance in some environments. In the Coastal Plain environments, all legume genotypes generally contributed to at least 50% of mixture biomass production. In the Maryland and Piedmont environments, the small grain dominated the cover crop mixture. Oats were generally more competitive with the legume species than barley or wheat. In the North Carolina Coastal Plain and Piedmont, several winter pea genotypes produced as much biomass in mixture as crimson clover and hairy vetch. Hairy vetch was the most competitive legume with the small grains across environments. The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations.
Agronomy Journal