In the experiment, the productivity of winter wheat grown with diversified nitrogen fertilization as a cover crop for the undersowns crop of seradella and white clover, as well as their mixture were compared. After wheat harvest, stubble crops of white mustard and fodder pea and their mixtures were sown. Field experiment was conducted in two growth seasons – 2004/2005 and 2005/2006 on Eutric Gleyic Cambisol, quality class IIIb and very good rye complex. Winter rape was the forecrop for winter wheat. Wheat fertilization with P and K amounted to, respectively, 33.4 and 74.7 kg. Wheat sowing was carried out annually in the third decade of September. The highest grain and wheat straw yield were obtained with nitrogen fertilization in the amount of 90 kg·ha^-1. The number of grains per spike and thousand grain mass increased under the influence of nitrogen fertilization, which consequently increased grain yield. Winter wheat created favourable growth and development conditions for the undersowns crop of seradella and white clover, as well as their mixtures, regardless of the nitrogen dose. Stubble crop growth after winter wheat harvest increased the amount of manurial biomass, and the amount of accumulated nitrogen depended on the biological properties of the grown species. Species mixtures within the range of undersowns and stubble crops made it possible to obtain a high yield of dry mass and in a better way met the idea of the introduction of biodiversity into sustainable agriculture in comparison with monocrops.

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