EN
Influence of organic, integrated and conventional systems on NPK and protein concentration in grain of winter wheat and spring barley was the aim of the research. Nitrogen and protein content in grain of winter wheat and spring barley in the organic system was smaller by 10-15% than those in conventional and integrated systems. Protein concentration in winter wheat grain from the organic system did not meet the trade standard (min. 11.5%). All systems did not differentiate phosphorus concentration in grain of both cereals. Grain of winter wheat from the organic system contained about 10% more potassium than the grain from two other systems.