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.
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.
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.
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.
Field pea can be used as a cover crop, green manure, forage, hay, and silage. Hay is good quality, but pea is more succulent than vetches and more difficult to cure. Regrowth after mowing or grazing is poor.
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.
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.
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.
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.