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.
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.
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.
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.
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.
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.
Three experiments whose objectives were to investigate cover
crop kill by winter freeze, weed suppression by 'Micah' barley and
other spring cereals, and allelopathic potential of cereal covers
were conducted at the Vegetable Research Farm and in the greenhouse
and growth chamber facilities at OSU in 1989/90. Kill by winter...
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.
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.