EN
One-factorial field experiment was conducted on light soil. The effect of crop rotations with different percentage share of potato and cultivation of catch crop on formation of weed seed bank in soil was examined. It was shown that in case of environmently correct crop rotation increased weed infestation of soil. It was particularly revealed in crop rotations with 50% percentage of potato. In two-field rotation with potato and winter rye the number of weed seeds in the entire ploughing layer was significantly higher (almost twice and a half) than in three-field rotation and in Norfolk crop rotation. The dominant species in the soil seed bank were Amaranthus retroflexus and Chenopodium album, and from among monocotyledonous Echinochloa crus-galli. The beneficial effect of ploughing down catch crop on reduction of weed seed bank was stated. After ploughing down mustard the number of diaspores in two-field rotation with potato and winter rye was significantly lower (by 28.3%) than in a similar crop sequence, but without catch crop.