Subterranean Clover (Trifolium subterranum)
Plant Characteristics: Subterranean clover is a winter annual legume with hairy leaves and hairy stems with large stipules. Leaflets are dark green and heart-shaped with a black spot. It has small, mainly white flowers form a small bur which is forced into the surface of the soil.
Establishment: Subterranean clover is a good reseeding species. It is ideal for foothill and nonirrigated pastures and hay fields, but not adapted to poorly drained soils. It is necessary to remove the forage by grazing, mechanical harvesting, or burning each summer to maintain clover in the stand. Recommended seeding rates range from 16 to 20 lb/acre and a special inoculant is needed. It should be planted from August 2o to September 30. However, good stands have been obtained with only 8 lb/ac when planting in a pure stand on a clean, firm seedbed using a drill. Planting depth is critical, seed should not be placed deeper than ½ inch. Well adapted to shaded areas.
Fertilization: Subclover is best adapted to soils ranging from a fine sandy loam to clay with a pH from 5.5 to 7. Like arrowleaf, it usually becomes chlorotic and stunted on soils with a pH above 7.3. For highest production of subterranean clover, soils should be well supplied with phosphorus and sulfur. If soils are low in pH, molybdenum may need to be applied. Apply 0.6 lbs Mo/ac as sodium malubdate dissolved in water once every 10 years. Specific fertilizer recommendations should be based upon soil test data and local Extension Service information.
Grazing/Hay Management: Forage production is greater in the lower south. Yields range from 0.5 tons/ac to 1.5 ton/ac and are produced from November through December and March through May. In order for reseeding to be successful, residual top growth must be removed before the fall rains. This can be achieved by forced grazing or burning. This removal allows the seed that has been buried from this year's crop to germinate and become established in the fall. The stoloniferous growth habit of subclover makes it well suited for close grazing animals like sheep, goats, and deer. Low stocking rates will prevent the re-establishment of subclover, resulting in a grass-dominant pasture. Increased stocking rates will help prevent weed invasion (except for various thistles). In addition, heavier stocking rates reduce the problem of summer forage removal. The best pasture management and animal production are obtained when pastures are grazed intensively. This, combined with adequate fertilization, will result in a high level of production of subclover-grass pastures.
Forage Quality: Subterranean clover forage is high quality from the period of growth initiation through early summer. As plants advance in maturity and set seed, forage quality declines. However, dry foliage is fairly high quality, typically 10% crude protein.
Varieties/Cultivars: Bacchus Marsh, Clare, Daliak, Larisa, Northam, Nungarin, Seaton Park, Trikkala, and Woogenellup, Mt Barker, Carridale, Denmark, Clare, and Nuba.