Trefoil a perennial, is a member of the Papilionaceae family is most commonly used as in grazing systems where alfalfa will not thrive, typically soils with low pH, poor drainage, poor native fertility or fragipans prone to heaving. There are over several species of trefoil with birdsfoot being the most commonly used.

Trefoil stems are smaller in diameter and less rigid than alfalfa stems and may grow to a height of 18 to 20 in(45-50cm). 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 portion of the soil profile.

Ideal Site- Like most members of the papilionaceae family trefoil does best in fertile well drained neutral soil, but is very adaptable to adverse conditions. The ideal soil pH is 6.0 - 6.5, but will tolerate pH levels to 4.5. Test the soil prior to planting. If soil pH is to low ad lime to the soil. Trefoil also makes a good meadow flower

Cultivation- 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 in (25mm) 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.

Uses-

1) Erosion control: Birdsfoot trefoil is used along roadsides to control wind and water erosion.
2) Birdsfoot trefoil is a choice food for Canada goose, deer, and elk.
3) This species is used for green chop, hay and pasture. It is seeded in combination with grass and grazed as a non-bloating   legume

Birdsfoot trefoil is commonly used in meadow mixes, and used for years by highway crews hoping to keep roadside growth low. It tends to form a solid mat, warding off taller-growing weed and grasses. Seed may be slow to grow into mature plants, but once established, it is incredibly hardy and permanent. Trefoil can be mowed and will bloom at lawn level.