Field trials were carried out at 2 sites in Russia to assess the effectiveness of rape as a weed-removing crop in different rotations. Rotations were fallow-wheat-barley-maize-wheat, and vetch-oat mixture and rape-wheat-barley-maize-wheat, with a control involving pure fallow. The degree of weediness (number of weeds/m 2) and species composition of weeds in young crops of wheat and barley was assessed twice (at tillering stage and before harvest). Before harvesting, weed mass was also assessed and the numbers of weed seeds in soil samples were determined. The substitution of rape crops for fallow in rotations resulted in significant reductions in weed numbers and weed seeds in soil. It is concluded that rape is effective in reducing levels of weeds in young crops and soils, even when minimal or no soil preparation is carried out.
