Topics : Species and Forage Variety Trials : Species Fact Sheets : Birdsfoot Trefoil
Species: Birdsfoot Trefoil
Additional birdsfoot trefoil information via the Forage Information System (FIS)
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.