Six seeding rates of cool season legume cover crops were evaluated to determine the optimum rates for biomass production at the James E. "Bud" Smith Plant Materials Center
Monocropping practices typically require the removal of large portions of above ground plant material which may hinder the overall sustainability of the agroecosystem due to the loss of soil carbon and soil organic matter, decreased soil productivity and soil moisture content, and increased potential for water and wind erosion. One way to mitigate potential losses, while maintaining the health of the agronomic system, is to offset above ground biomass removal by utilizing cover crops during the off-season. The USDA-NRCS James E. “Bud” Smith Plant Materials Center evaluated above ground biomass production of five cool-season legume species to determine appropriate seeding rates for use in agronomic systems in the Texas Rolling Red Plains. ‘Frosty’ berseem clover (Trifolium alexandrinum), ‘Dixie’ crimson clover (Trifolium incarnatum), VNS common vetch (Vicia sativa), ‘AU Merit’ hairy vetch (Vicia villosa), and ‘Wyo’ winter pea (Pisum sativum) were sown at rates of 25, 50, 100, and 150% of the suggested Sustainable Agriculture and Research Education planting rates, both as a monoculture, and as a component of a cover crop mix with ‘Wrens Abruzzi’ cereal rye (Secale cereal).
Increasing the seeding rate of annual cool-season legumes did not significantly increase biomass yield when planted with or without a cereal rye cover. Cereal rye produced the most consistent biomass regardless of the legume species or legume seeding rates. When planted as part of a two species mix, berseem clover produced more biomass at 100% versus the 150% planting rate and crimson clover produced more biomass at 25% versus the 150% suggested planting rate. Common vetch produced more biomass at 100% whencompared to 150%, and winter pea when planted at the 25% rate, yielded greater than the 50% rate when planted as a single species (without a rye cover). Hairy vetch, at 150%, produced the greatest biomass with and without a rye cover of all legume species.
These data suggest lower planting rates were as productive as full planting rates for these specific cool-season cover crop species. Additional testing on different soils and under different climatic conditions in northwest Texas and southern Oklahoma are needed to verify these findings. Refer to the final study report for full details of this study.
Technical information and guidance on the use of conservation plants to address resource concerns can be found on the Plant Materials Program website or contact the nearest Plant Materials Center or plant materials specialist. For additional information on specific species of plants mentioned, please see the USDA PLANTS database.