Birdsfoot Trefoil Seed
Birdsfoot Trefoil (Lotus corniculatus)Birdsfoot trefoil is a rather deep-rooted perennial and can be long-lived in areas where it is adapted. Trefoil pods are very prone to shatter, therefore the long-lived reputation of this crop can often be attributed to the growth and seed production of volunteers. It thrives on poorly drained soils of moderate to high acidity, and is also fairly tolerant of salinity. The traditional production area was eastern Canada, but winterhardy varieties have resulted in a large movement of seed acres to Manitoba.
SeedingThe plants are poor competitors in the seeding stage and slow to establish. A companion crop is definitely not recommended. Inoculation with the proper bacterial inoculant is very important, especially for land that has not grown trefoil before. Early seeding and good weed control are essential. Seed at about four lbs/acre (4.5 kg/ha) to a depth of about one-half inch (1.25 cm) in rows spaced 12 inches (30 cm) apart.
FertilizersFertilizers usually are not required. If a soil test indicates a lack of phosphorus, potassium or sulphur a corrective application should be worked into the soil before seeding.
Honey bees are effective, and one to one and one-quarter strong colonies per acre should be provided. Leafcutter bees are also effective pollinators. Some growers allow the first growth to set seed. Others get better results by clipping the stand in early to mid-June. This delays flowering and gives time for bee populations to build up. The growing season on the prairies is too short to permit clipping.
Insect ControlInsect control is rather unusual, but one should follow good field sanitation practices and remove or burn harvest residues. In Ontario the chalcid fly has become very severe (up to 50% yield losses) and has resulted in a reduction in trefoil seed acreage in this province.
HarvestingRipe pods pop open and shatter seed when dry. Thus, swath birdsfoot trefoil when it is damp with dew or rain. Swath when 60 to 70% of the pods are golden brown. If greenish-white coloured pods are cut they will mature seed of high germination, but seed appearance is not as bright as seed from brown pods. Allow about two days of good drying weather before picking up swaths. This means threshing on the "tough" side and drying out the seed; usually after green material has been cleaned out. The seed will dry in about two days if it is spread two to three inches (5 to 7.5 cm) deep on a well-ventilated floor space and stirred frequently. A commercial air dryer may also be used. Another way to dry the seed is to mix it with several times its bulk of finely-ground, kiln-dried sawdust. The sawdust is removed later with a fanning mill or other cleaning equipment.
Straight combining is possible if the growth is first treated with a chemical defoliant. Another method is to bale swaths when tough, and thresh them when thoroughly dry. The suggested settings for the thresher are about one quarter inch (0.63 cm) clearance for the concaves, and a cylinder speed of 950 -1200 r.p.m.