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Characteristics of Birdsfoot Trefoil

Production of high-quality forage for cattle and sheep has traditionally been difficult on marginal lands in Pennsylvania and New York. Soils with few limitations are generally sown to alfalfa. Soils with low pH, poor drainage, poor native fertility or fragipans prone to heaving are not suited to alfalfa production. Birdsfoot trefoil (Lotus corniculatus L.) is a forage legume that is more tolerant of these adverse production conditions.

Birdsfoot trefoil is a perennial legume that is adapted to production on poorly drained, low pH soils. It can reseed itself, is resistant to Phytophthora root rot and numerous alfalfa insects, responds well to fertilization and does not cause bloat in animals. These characteristics have resulted in its expanded use in the northern United States and southern Canada where production of other forage legumes is limited. Trefoil has traditionally been used in forage grazing systems. Varieties are now available that are suitable for hay production.

Trefoil stems are smaller in diameter and less rigid than alfalfa stems and may grow to a height of 18 to 20 inches. Each yellow flower (4 to 8 per stem) produces one seed pod. Seed pods are at right angles to the flower stalk and resembles a bird's foot, hence its name. Its root system consists of a tap root with numerous lateral branches predominantly located in the upper 15 inches of the soil profile.

As with other forage legumes, trefoil is most productive on fertile, well-drained soils with near neutral pH. However, it has the ability to produce relatively high yields and quality on land that is marginal for alfalfa production. Trefoil can be grown on low pH (5.5) soils and will tolerate short periods of flooding with less yield reduction than alfalfa. It can also tolerate periods of drought, which makes it suited for production on both sandy and clay soils.

In soils that are well drained and have good fertility, birdsfoot trefoil will not yield as well as alfalfa. Yields usually are 50 to 80% that of alfalfa in these soils. Therefore, the site in which trefoil is to be grown should have limitations which make alfalfa production difficult.

Adapted Birdsfoot Trefoil Varieties

About 25 varieties of birdsfoot trefoil are currently available in the United States and Canada. Birdsfoot trefoil varieties are generally characterized by growth habit into two types, Empire and European. Both types are referred to as "broadleaf" trefoils.

Empire-type birdsfoot trefoils are better adapted for use in grazing situations since they have fine stems, prostrate growth and indeterminate growth habit. The Empire types are also slower growing during establishment and regrow more slowly following harvest than the European types. Dawn and Empire are high- yielding Empire types that have performed well in Pennsylvania tests.

European-type birdsfoot trefoils are better adapted to hay production practices since they are more erect, establish faster and regrow faster after harvest. Viking, a European type trefoil, has traditionally been a high-yielding variety when produced for hay in Pennsylvania and New York. Newer varieties Fergus, Norcen and Tretana have production attributes similar to Viking, and also tend to persist better under more vigorous harvest management. This characteristic may allow three cuttings per year in some areas of Pennsylvania and New York.

Birdsfoot Trefoil Establishment

Birdsfoot trefoil requires careful management for successful establishment because of its small seed size and poor seedling vigor. Before seeding, trefoil seed should be inoculated with Rhizobium lupini bacteria, which are specific for birdsfoot trefoil. This will ensure sufficient nodulation of the root system and adequate atmospheric nitrogen fixation.

The small seed of trefoil necessitates that the seed be placed no deeper than 1/4 inch in the soil to achieve maximum stand and yield. A smooth, firm seedbed will greatly facilitate accurate depth placement of the seed. Early spring seedings are generally more successful than late summer seedings.

Firming the soil before and after planting will improve the seeding depth and seed-to-soil contact, which improves moisture uptake by the seed and ultimately enhances germination and emergence. Seeding rates of 8 to 10 pounds per acre are considered adequate under normal conditions.

The low seedling vigor of trefoil has brought into question the value of a companion or nurse crop when establishing this legume. Small grain companion crops reduce root development, seedling vigor, stand density and yield of trefoil. If a companion crop is used, it should be seeded in 18- inch row spacings and removed early before competition for light becomes too great and before the companion crop begins to lodge. For pure seedings of trefoil, chemical weed control is generally necessary because most weeds grow faster and are more competitive than trefoil.

Trefoil establishment on soils that have a pH less than 5.6 may result in molybdenum (Mo) deficiencies. Molybdenum is an essential nutrient for nitrogen fixation. When needed, Mo can be applied as a seed coating. This method of application should provide sufficient Mo levels for the life of the trefoil stand.

Birdsfoot Trefoil Harvest Management

When harvested as hay, the first cutting of birdsfoot trefoil should be taken at 1/10th bloom and a second cutting in mid to late August. Sufficient time for regrowth between cuttings or grazing is recommended for stand maintenance. Root reserves may not be sufficient to initiate regrowth if the trefoil plant is totally defoliated in midsummer when root reserves are low.

Trefoil is not as resistant as alfalfa to Fusarium-type diseases , therefore, individual trefoil plants will not survive as long as alfalfa. In order to maintain a stand of trefoil, a management system which allows the trefoil to reseed itself is necessary.

Heavy grazing pressure may be needed in the spring to reduce lush growth and allow trefoil to better compete in a grass mixture. Trefoil will compete under continuous grazing better than alfalfa. However, close, continuous grazing is not recommended because trefoil regrowth depends on energy supplied by top growth. Unlike alfalfa, trefoil does not maintain high levels of root reserves during the summer.

Harvesting or grazing between September 1 and the first killing frost is not recommended. This period is needed to allow root reserves to accumulate to improve winter survival and growth the following spring.

Birdsfoot trefoil quality is greater than that of alfalfa because of increased "bypass" protein and smaller stems. Loss of quality with maturity is less pronounced with trefoil than alfalfa. However, leaf loss during hay making may be greater than alfalfa. When grazed, trefoil is more palatable than alfalfa and produces greater average daily gains and meat yield per acre for heifers and sheep. Unlike alfalfa, grazed trefoil does not cause animals to bloat.

The practice of not harvesting birdsfoot trefoil during the second half of the summer and grazing it in the fall after the first killing frost is known as stockpiling. Trefoil is well suited for stockpiling since it holds its leaves at maturity and after frosts, thus maintaining a relatively high level of quality. Stockpiling also allows root reserves to accumulate during the fall, which improves plant survival and spring growth.

Birdsfoot Trefoil Fertility

Although trefoil seedings will nodulate and fix nitrogen in soil with a pH as low as 4.5, maximum nodulation occurs at pH 6.0 to 6.5. Lime should be applied to low pH soils as recommended by a soil test.

Trefoil will produce better than alfalfa on poor soils, but its fertility requirement for high yields are similar to those for alfalfa. Fertilizer applications at establishment should be based on a soil test. In the absence of a soil test, assuming a medium- fertility soil, plow down 0-45-135 lb per acre and apply 20-60-20 lb per acre in the row at seeding (banded if possible). When fertilizer recommendation exceed this amount, the fertilizer should be incorporated into the seedbed prior to planting.

Soil testing is the best guide for determining fertilizer requirements of established stands of trefoil. When the trefoil makes up more than 30 percent of a mixed trefoil and grass stand, no N fertilizer should be needed. However, if trefoil makes up less than 30% of the mixture, up to 50 lb N per acre will be needed to meet the grass demand for N and to maximize production. Nitrogen fertilization of a trefoil stand with fertilizer N or manure will reduce the N fixing ability of trefoil and increase the competitiveness of the grass or weeds that also may be in the stand.

Birdsfoot Trefoil Summary

Birdsfoot trefoil yields less than alfalfa on well-drained, fertile soils but is superior to alfalfa on soils that have marginal fertility and production capabilities. In areas of New York and Pennsylvania where alfalfa production is not optimal, trefoil may be a viable alternative in forage production systems. Its excellent grazing potential and bloat- free characteristics are ideal for pasture. Poor seedling establishment has been a major complaint of trefoil. Careful management at seeding can reduce this problem considerably. Careful harvest or grazing management is necessary, but when properly managed, birdsfoot trefoil will persist and remain productive for several years.

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This page was last updated on November 16, 2002