Kura clover: a legume for permanent pastures.

摘要

Kura clover (Trifolium ambiguum) is an exceptionally persistent forage legume with a high nutritional quality. Persistence is a characteristic that is lacking with many legumes currently used in temperate environments. The extensive roots and rhizomes system of Kura clover acts as a carbohydrate reserve during periods of stress allowing it to recover from grazing disturbances. Establishment problems have so far prevented a wide utilization of this species, but the use of new more efficient rhizobial strains, of more competitive cultivars, and of appropriate sowing techniques can now minimize these problems. Kura clover is a winter-hardy plant that can grow under various edaphic conditions. In addition to its rhizomes, this perennial forage species develops a deep taproot conferring it drought resistance. It is also more resistant to poor drainage than red clover and white clover. Kura clover has the reputation of being a species resistant to many of the diseases and pests commonly affecting other forage legumes; however these claims must be taken with caution. As Kura clover is slow to establish, it thus has lower forage yields in the first two years when compared to other legumes, often producing <500 kg ha -1 in the sowing year. However, once established, it becomes highly productive and has been reported to be amongst the highest yielding forage legume, while having the highest persistence across a range of environments. This patter of yield evolution underlines the interesting role Kura clover could play in permanent pastures as a long-term legume component. As it causes bloat if grazed as pure stands, it is highly recommended to use it in mixture with grasses. Established swards of Kura clover are giving good early spring production. Kura clover yields are generally higher at the first cut or grazing period of the season and decrease throughout the summer. The use of good sowing yield will often be maximized when established in pure stands with a preplant herbicide. Good establishment and a satisfying botanical composition can also be obtained when sown in mixture with grasses or when sod-sown. In these situations, competition should be minimized. Broadcast sowing of Kura clover generally results in poor establishment. Kura clover has very specific rhizobial requirements and it has been reported to nodulate much more slowly than other legume species. Nitrogen fertilizer application may thus improve establishment in N-limited soils. New more efficient rhizobial strains have however been recently isolated. These strains may double the dry matter production of Kura clover in the first four months of growth compared to plants inoculated with commercial strains commonly used. Kura clover is thus a promising species that can play a significant role in permanent pastures by becoming a persistent and highly nutritious legume component of the sward..