EN
In 2-factorial field experiment set up by split-plot design and conducted in 2009 and 2010, 5 mixtures of species were grown: barley + oat + wheat, barley + oat + triticale, barley + wheat + triticale, oat + wheat + triticale and mixture of all four species. The main experimental factor was nitrogen fertilization applied at the doses: 40 and 80 kg N/ha. The results of performed studies revealed that with the increase of nitrogen doses decreased the weed number in cereal mixtures on the average of 25.3% and 77.8% in successive years as well as decreased weed dry weight in the second year, by 73.4%.The number of weeds was not related to the type of cereal species mixture. In the first year, in the mixtures of barley, oat and triticale and mixture of oat, wheat and triticale a lower value of weed dry weight was recorded comparing to the mixture of barley wheat and triticale.