Soybeans serve as one of the most valuable crops in many countries, including Poland, due to the high nutritional value of its seeds, its resistance to diseases and pests. Under the climatic conditions of Poland, soybean yield is largely dependent on weather conditions in a particular growing season, primarily temperature and rainfall. The aim of this study was to evaluate the effect of cover crops (winter rye, winter oilseed rape, and white mustard), mulching method (aboveground biomass mulching after mowing or desiccation) and reduced herbicide rates (down to 75 and 50% of the recommended rate) on soybean seed quality and yield. The present study showed that the weather conditions in the particular study seasons and mulching treatments caused the greatest variation in soybean seed yield and its quality. The highest yield was obtained from control treatments, desiccated winter rye and white mustard. The applied herbicide rates did not cause variations in seed yield and yield component traits. The protein and oil content was affected by the type of the mulch plant used. Mulch with rye and winter rape favors increased protein content, while more oil seed were accumulating after the white mustard and both mulch forms of rape.

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