In 1990-2000 an experiment on average soil investigated the response of cereal mixture of spring barley and oats (50% each) and these cereals separately in pure stand to different crop-rotation positions of a 4-field crop rotation system (with 25, 50 and 75% share of these crops). The cereals returned to the same rotation position after 3 years (after potato), after one year (after potato and field pea) and once or twice after themselves. The evaluation criteria were: grain productivity per unit and its variation throughout the years and some yield structure components. Over 11 years, the cereal mixture yielded significantly higher and the yield was more stable than spring barley and oats cultivated separately. The mixed cultivation showed to be a factor easing the effects of an excessive share of cereals in crop rotation. It was found that a cultivation of the same cereal mixture after a year break did not result in a significant decrease in its productivity, while its cultivation without rotation decreased it less considerably than in spring barley and oats. The mixed fields were usually more compact than the cereals in pure stand and barley was a dominant cereal in the mixture. For both components, their mixed cultivation enhanced the length of the culm and grain plumpness and in barley – also the length of the ear.

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