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前言近年来英国每年播种禾本科与白三叶草混合草地,使用900—1000吨白三叶草种子,花费三百万英磅左右的成本。然而,由于白三叶草对牧场草地牧草产量的贡献很少,投资效益很差。许多因素(气候、土壤、草地、牲畜、经营管理)单独或相互作用,可能引起白三叶草表现不稳定。施用氮肥,由于它加强了禾本科牧草对三叶草的竞争,主要影响混播草地禾本科—三叶草之间的关系。一批叶片大小不同的白三叶草品种在施氮的草地上,同禾
Foreword In recent years, Britain has planted grasses and white clover mixed grasslands each year, using 900-1,000 tons of white clover seeds, costing about 3 million pounds. However, the investment benefits are poor due to the small contribution of white clover to grassland pasture production. Many factors (climate, soil, grassland, livestock, management) alone or in interaction may cause white clover instability. Nitrogen fertilization, as it strengthens the competition of grasses for clover, has a major impact on the relationship between grass-clover and clover in mixed-sown grasslands. A group of white clover varieties with different leaf sizes were planted on the nitrogenous grassland with the same crop