October 3, 2001
Hairy vetch is a winter annual legume that offers a number of potential benefits to row-crop or livestock producers when used as a winter cover crop. Though a good stand of this winter annual legume alone can provide good cover, it also can make a good companion species to ryegrass and, in particular, small grains.
In addition to protecting land from erosion, hairy vetch can provide spring pasture for livestock. In other cases, producers plant it with winter annual grasses, especially small grains. They then harvest the forage for hay or silage.
Most common use
The most common use of hairy vetch is as a green manure crop to be turned under a nitrogen source just prior to planting a summer row crop such as corn, cotton or grain sorghum, or an annual forage crop such as pearl millet or a sorghum-sudan hybrid. There is little advantage in turning under vetch prior to planting soybeans or other legume crops, since legumes fix their own nitrogen.
About 3.5 percent of the dry matter of hairy vetch is nitrogen, so a substantial amount of nitrogen is available in forage and roots when turned under prior to planting a summer crop. The timing of turning under a vetch cover crop in such situations is important. Only a few weeks can make a great deal of difference in the amount of growth - and thus nitrogen — present in the vetch forage and roots. Even vetch that has been grazed prior to being turned under will provide nitrogen for a summer crop, although the amount will be reduced as compared to a stand that is not grazed.
Vetch is particularly well suited to being used as a winter cover on fields in which summer row crops are to be planted by no-till methods. Vetch makes heavy spring growth that chokes out summer weeds. It is easily killed by desiccants at planting time and it provides a good mulch for conserving moisture. Yet, it deteriorates quickly enough so that it does not create problems later in the growing season.
It has long been known that hairy vetch can help conserve soil and water resources and also serve as an inexpensive source of nitrogen in conservation-tillage systems. Unfortunately, common hairy vetch does not flower until late spring, after many Southern farmers have had to turn under or kill a cover crop in preparation for spring crops. In such situations, producers cannot reap the full benefits from growing this legume.
The variety AU EarlyCover, developed by Auburn University and the USDA Natural Resources Conservation Service, should be of interest to many producers. This is an early flowering variety that can more nearly maximize the potential of hairy vetch in the South. The main selection criterion during the three cycles of selection was early flowering date. Other important criteria included vigor, pest resistance and uniform morphological traits.
Extensive testing for forage yield, maturity, canopy height, composition and diseases of hairy vetch lines was conducted throughout Alabama and in Americus, Ga. AU EarlyCover was shown to be an excellent cover crop because of its early growth.
When this cultivar is harvested or incorporated into the soil as a green manure on or around April 1, it typically has a dry matter yield superior to common hairy vetch. Therefore, it can be turned under earlier than common hairy vetch.
AU EarlyCover is well adapted to the central and southern parts of Alabama and Georgia and areas of similar climate. The plants flower 23 to 36 days earlier than commercial hairy vetch. Crude protein content of AU EarlyCover is about 27 percent on April 1.
AU EarlyCover also is a better choice than common hairy vetch for forage purposes for producers who want to provide early spring grazing for livestock. It also can be a superior legume companion with small grain that is to be cut for silage or hay. Its maturity — and the optimum harvest date — better match that of the small grains.
Hairy vetch is best suited to be grown on well-drained, productive land suitable for summer row-crop production. The site selected should not be subject to prolonged overflow, and excessively shallow soils should be avoided.
On fields where hairy vetch is to be planted, lime should be applied as needed to bring the soil pH within the range of 5.8 to 6.5. At or near planting time, phosphorus and potassium should be applied according to soil test recommendations. Where a hay or silage harvest isn't made, practically all of the nutrients added in the fall will be available for use by a summer crop planted behind the vetch. If small grains and/or ryegrass are planted with the vetch, 60 pounds of nitrogen per acres should be applied at or near planting time.
Ideally, hairy vetch seed should be planted at a depth of one to two inches. Broadcasting seed followed by light disking and culti-packing is the most common planting method.
The Auburn University seeding recommendation for hairy vetch is 20 to 25 pounds of seed per acre if the seed is to be broadcast. If planted with a small grain, 20 to 25 pounds of vetch and 60 to 90 pounds of small grain per acre makes a good mixture. It's important to inoculate the seed with fresh vetch inoculum just prior to planting. In the deep South, hairy vetch can be planted from early September to mid-November, depending on location. Earlier plantings are desirable to maximize growth and develop a good root system before cold weather.
As with other winter annual forages, vetches should not be grazed until at least six inches of growth has accumulated. Grazing animals should be removed from the pasture during extremely muddy periods, especially when the plants are small. If it is to be used for hay or silage, hairy vetch should be cut in the early bloom stage.
Hairy vetch should be allowed to make a seed crop the first year and at least once every two years thereafter if reseeding is desired. For best results, the seed should be incorporated into the top few inches of soil soon after they mature. If reseeding is desired, livestock should be removed by mid-March.
AU EarlyCover hairy vetch is being marketed by Seed South in Dothan, Ala. (1-800-633-7523). To locate other sources of the seed, contact Southern Proprietary Seeds, Lake Oswego at (503) 636-2600.
e-mail: [email protected]
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