The Best Legumes for Cover Crops

Hairy Vetch

• Hairy vetch (Vicia villosa) gets its name from the fine hairs that cover stems and small leaves. It is a sprawling ground cover that uses tendrils to cling to structures as high as 8 feet tall. Because of its tolerance to cold weather, it is usually planted in the fall, reaching its maximize size in late spring. It can add as much as 140 pounds of nitrogen per acre. Because hairy vetch is low growing and completely dies in warm weather, warm weather vegetable plants, such as tomatoes, can be planted directly into the ground in spring while surrounded by the cover crop.

Cowpea

• The cowpea (Vigna unguiculata) is also known as the black-eyed pea or southern pea. It is an annual legume used as a summer cover crop since it is not cold tolerant. It produces broad leaves that shade out weeds and a deep taproot that seeks out moisture, which makes it tolerant of dry soils. The seeds, or peas, are produced in long pods that are often harvested before they dry and cooked in a variety of dishes.

Soybean

• Soybean (Glycine max) is considered one of the highest biomass and nitrogen-producing cover crops for warm weather. The taproot can grow as long as 6 feet into the ground making the soybean more drought tolerant that other warm weather legumes used as cover crops. The broad leaves shade out weeds that compete for moisture and nutrition. Soybean plants are tolerant of a variety of soils.

Alfalfa

• Alfalfa (Medicago sativa) is considered one of the highest quality forages for livestock. It has a deep taproot but must be planted in well-drained soils loosened to a depth of at least 3 feet. Alfalfa is capable of gathering nutrients, including nitrogen, from the soil and air with its extensive root system. When it is tilled under the soil, the concentrated nutrients are returned to the soil. Alfalfa is planted in the fall before cool weather arrives. Although drought tolerant, alfalfa grows best with supplemental moisture during dry periods.

Clover

• Clover (Trifolium) is one of the most widely used legumes for a cool weather cover crop. In areas with mild summers, it can be grown during the warmer months. There are many varieties of clover used as cover crops, but sweet clover, red clover and white clover are the most often used. These varieties can add as much as 100 pounds of nitrogen per acre into the soil when tilled under in the spring.