Soils with few limitations are generally sown to alfalfa. 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. 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. It can also tolerate periods of drought, which makes it suited for production on both sandy and clay soils.