Soil to Bed Over Winter
By Hank Becker
February 13, 2001
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
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
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
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
Agricultures chief scientific research agency.
Scientific contact: Thomas E. Devine, ARS Sustainable Agricultural
Systems Laboratory, Beltsville, Md., phone (301) 504-6375, fax (301) 504-6491,