The paper presents the results of strict field experiments of irrigation and nitrogen fertilization of winter oilseed rape variety "Californium" conducted in years 2007-2010 at the Research Station of the Faculty of Agriculture and Biotechnology, University of Technology and Life Sciences in Mochełek near Bydgoszcz on sandy soil. In each season of spring vegetation have appeared needs of water supplementation using irrigation, an average of 93 mm were used (pri-marily in May and June), but during the years of research the dose ranged from 55 mm in 2009 to 150 mm in 2008. Two doses of nitrogen fertilizer were used: 125 i 200 kg.ha-1.On average, in the years of the research the rape yielded at the level of 4.41 t.ha-1. Applied the factors resulted in increased yield: irrigation of 1.13 t.ha-1 (29.3%) and nitrogen fertilization, of 0.37 t.ha-1 (8.7%). The largest increase in rape seed yield due to irrigation (1.27 t.ha-1) was obtained in 2008, using the highest dose of water (150 mm). The smallest (55 mm) dose of irrigation water in year 2009 brought the largest (21.6 kg) efficiency of 1 mm of the water. Irrigation resulted in a substantial, compared to fertilization, improvement of yield compo-nents, increasing ...
