Cover crop selection and management depend on many factors, among them the cover crop’s ability to accumulate dry matter (i.e., residues) and nitrogen (N). Dry matter provides energy for soil organisms, contributes to soil organic matter, improves tilth, and acts as a sink for nutrients.
Crimson clover may be used as a cover crop, green manure, pasture, or hay. It often is used as a winter annual cover crop in annual rotations. It has been used successfully in reduced-tillage farming systems, and in orchards and vineyards where it can be managed to reseed itself.
Published January 1998. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Buckwheat is not likely to increase
soil organic matter content much
because dry matter production is
relatively low and tissues are succulent
and decompose very rapidly
when incorporated. However,
buckwheat can improve short-term
soil tilth and has been used to
prepare fields for transplants.
Rapeseed is grown for its oil and meal, and as a cover crop. Rapid fall growth captures part of the available soil nitrogen, which otherwise might be lost to leaching, and provides good ground cover over winter.
Annual ryegrass is an erect, robust cool-season bunch grass that reaches a height of 3 to 4 feet. Plants are yellowish-green at the base and have 12-inch long glossy leaves. This species has a heavy, extensive, fibrous root system.
Subclovers are used for forage and hay and have been used successfully in Oregon as fall-planted and relay interplanted cover crops in annual rotations. They are capable of accumulating substantial amounts of N, a portion of which is available to the following crop. Rapid growth suppresses weeds in spring.
Common vetch is a viny, succulent, annual legume attaining a height of 24 inches when planted alone. It grows taller when planted with a tall companion crop that provides structural support for climbing.
Sudangrass and sorghum sudangrass crosses are used as warm season cover crops, forage, and silage. When used as a cover crop, their fibrous roots and organic matter contributions improve soil structure; and their rapid, dense growth suppresses weeds.
Hairy vetch is used as a cover crop, green manure, pasture, silage, and hay. It is capable of accumulating large amounts of dry matter and nitrogen. When planted alone as a winter cover crop in annual vegetable rotations, it can provide substantial amounts of nitrogen (N) to a following crop.
Fava bean is used as a winter or spring cover crop, green manure, silage, forage, hay, and vegetable. It is capable of producing large amounts of dry matter and accumulating large quantities of nitrogen (N), part of which is available to subsequent crops.
Cereal grains are grasses and may have a prostrate, semierect, or erect physical stature. All have fibrous root systems.
Barley, oats, triticale, and wheat are each comprised of hundreds of varieties whose growth characteristics vary considerably.
Cover crops planted in late summer are an inexpensive way to build better soil for gardening. Cover crops often are
called green manure crops. They are grains, grasses, or legumes that will grow during fall and winter and that you
can plow, spade, or till under in the spring.