Crop Rotation and Weed Control as Factors in the Sustainable Cultivation of Winter Oilseed Rape

The competitive ability of weeds against crop plants is determined by the amount of macronutrients taken up from the soil. Macronutrient uptake is influenced by nutrient concentrations in plants and, above all, the amount of weed biomass produced per unit area. The present study was conducted as a part of a field experiment with winter oilseed rape, which has been carried out since 1967. Winter oilseed rape has been grown continuously since 1967 in the same field and in a six-field crop rotation. In winter oilseed rape monoculture, weed management was implemented to mitigate soil fatigue. Winter oilseed rape yields were twice as high in crop rotation than in monoculture, and weed biomass was more than three times higher in the continuous cropping system than in crop rotation. Winter oilseed rape yields were higher in crop rotation without a weed control than in monoculture, including monoculture with a weed control. Nitrogen (N) uptake by rape seeds and straw was significantly higher, whereas N uptake by weeds was lower in crop rotation than in monoculture. In all years of this study, N uptake by weed biomass was higher in monoculture than in crop rotation due to higher weed infestation levels in the continuous cropping system, and N uptake was not significantly affected by N content. The weed control induced a greater increase in N uptake by rape seeds and straw in monoculture than in crop rotation. The results indicate that integrating crop rotation with herbicide protection can help increase yields while reducing weeds, which promotes a more sustainable crop production system. The use of crop rotation contributes to a more efficient use of nitrogen by crops, while reducing its uptake by weeds.