Cthe aim of this study was to determine the effect of the cultivar and mineral fertilization, taking into consideration the use of ash from wheat straw, on biomass production of winter oilseed rape. Also changes in pH value and the contents of forms of macroand microelements available for plants in typical lessive soil after three years of using different rates of ash from winter wheat straw was assessed. In 2010-2012 at the Research Station in Mochełek, belonging to the University of Technology and Life Sciences in Bydgoszcz made tripartite experience, which has been studied interdependent interaction of diverse nitrogen-phosphorus fertilization (90 kg N + 15,3 kg P·ha^-1; 90 kg N + 30,6 kg P·ha^-1; 180 kg N + 15,3 kg P·ha^-1; 180 kg N + 30,6 kg P·ha^-1) and the impact of ash from winter wheat straw (0; 0,25; 0,5; 0,75 i 1,0 Mg·ha^-1) of biomass production of two cultivars of winter oilseed rape (SW Gospel, Ekstend F1). The study found that the productivity of hybrid rape Extend F1 was higher than the population cultivar SW Gospel. Increased biomass production, especially post-harvest residues, such qualifies for cultivation in the conditions of straw management on non-agricultural purposes, as a potential source of soil organic matter. High biomass production of winter rape, including post-harvest residues, require high nitrogen fertilization. If the soil is rich, it is possible while limiting phosphorus fertilization. The ash from wheat straw, supplemented by nitrogen fertilization and phosphorus, used at a dose of 1.0 Mg·ha^-1 impacted favourably on seed yield and straw of winter oilseed rape, and also allowed after three years of application to keep without significant changes in soil pH and the content in it available plant macro-and micronutrients.

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