Field experiments were carried out at the Didactic and Experimental Farm in Swadzim (52^o26’ N; 16^o45’ E) near Poznań in the years 2004-2007. The experiment was carried out in a „split-plot” design with 3 experimental factors and 4 field replications. Two cultivars were studied, 6 doses of nitrogen, one dose of magnesium and the method of fertilizer application were investigated. The content of total protein and N-free extract in the dry matter of grain depends exclusively on the level of nitrogen fertilization. As far as ash content is concerned, it was found that the value of this feature depends only on the cultivar factor. The contents of raw fibre and raw fat were not determined by any of the experimental factors. A higher yield of total protein was obtained from the hybrid LG 2244 in comparison with Anjou 258. Analysis of the amount of nitrogen fertilization has shown that the significantly highest yield of protein was obtained for a dose of 90 kg N^.ha^-1. On the other hand, a further increase in nitrogen dose caused a significant breakdown of this feature value. Magnesium fertilization amount and the method of its application did not exert any effect on the yield of total protein. The concentration of net energy was not affected by any experimental factors, while the yield of grain net energy was determined by the amount of nitrogen fertilization. The yield of digestible protein depended in a significant way on the cultivar factor and on nitrogen fertilization.

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