Read: more details in Agricultural Research.

Putting the Soil to Bed Over Winter

Winter cover crops can provide a wealth of ecological and financial benefits for farmers and gardeners--especially if these crops have been fine-tuned for local use.

In sustainable agricultural systems, farmers and gardeners need new nitrogen-fixing winter cover crops to help reduce weeds and herbicides, add nitrogen and improve soil quality and tilth.

ARS geneticist Thomas E. Devine at the Sustainable Agricultural Systems Laboratory in Beltsville, Md., has a 13-year plant breeding program under way to meet these needs. He is breeding, testing and selecting two potential species--hairy vetch, Vicia villosa, and subterranean clover, Trifolium subterranean. He wants to make these crops more useful to farmers and gardeners who grow crops in sustainable agricultural systems.

Both cover crops are legumes that form a symbiosis with specialized soil bacteria called rhizobia. These bacteria take nitrogen from the air, convert it to a form the plants can use, and store the nitrogen in nodules on legume roots. The next crop seeded after the cover crop can use this readily available nitrogen.

Since the spring of 1998, Devine has evaluated 451 lines of subterranean clover, earmarking those with better winter-hardiness and seedling vigor. He is testing them to determine whether genetic variability exists for winter-hardiness, seedling vigor and thatch production.

Since the fall of 1998, Devine has been evaluating 53 accessions of hairy vetch, to identify those useful as parental material. His goal: develop earlier flowering cultivars with more vigorous cool-season growth for use in green manure/mulch systems for sustainable agriculture.

For more details, see the February issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Scientific contact: Thomas E. Devine, ARS Sustainable Agricultural Systems Laboratory, Beltsville, Md., phone (301) 504-6375, fax (301) 504-6491, devinet@ba.ars.usda.gov.