Many species of grasses, legumes, and other forbs can be used as cover and green manure crops, sometimes called living mulches. For quick cover and abundant roots, grasses are a good choice. To increase soil fertility, nitrogen fixing legume species are popular. For reducing nematodes in crop rotations or "flash grazing" applications, brassica species can be helpful, either alone or in combination with annual ryegrass. To learn more about the individual species, choose the species of interest from the following drop-down menu or click on the species grouping of interest from the left-hand menu (Grasses, Legumes, or Other Forbs). The UC-Davis Cover Crop Database also has links to additional species.
When establishing a cover crop, match the cover crop species not only with the job traits desired, but also with the soil type and conditions.ﾠ Some species grow better than others in low fertility and/or poorly drained soils.ﾠ A review of a soils map and a soil test will help evaluate the soil.ﾠ
Once the cover crop species is selected, it is critical to always sow good live seed.
When planting leguminous cover crops such as clover, vetch, lespedeza and soybeans, be sure to inoculate the seed before planting.
Cover crops usually can be planted using [reduced] tillage or conventional tillage systems.
In conventional tillage planting, the soil is tilled with a plow and/or disk. If soil erosion is not a major concern, tillage is a good way to eliminate some weed competition and to prepare a good seedbed. Seed can be broadcast or drilled, however, rolling the field with a cultipacker before and after seeding will improve the seedbed quality. Rolling prior to planting firms the soil and prevents seeds from being buried too deep. Rolling after planting insures good seed/soil contact. Rolling also takes the “fluff” out of the soil, which helps retain soil moisture.
In a [reduced] tillage system the soil is not disturbed and the cover crop seed can be broadcast seeded by hand with a cycloned-type seeder into standing vegetation or bare soil. This seeding method is often used when competition from an existing crop or from weeds will be low, giving the cover crop time to establish. The fall and late inter are good times for [reduced] tillage seeding. Later winter seedings, or “frost seedings,” are where the seed is in place for quick germination as soon as the weather warms up. This puts the newly developing plant ahead of most weeds.
Incorporation and Removal