Development of weed populations with no-tillage of winter wheat into living mulches

No-tillage without soil disturbance is a suitable tool to prevent soil erosion and the leaching of pesticides and plant nutrients to the ground water. For the success of such modem cropping systems, efficient weed management is essential. Until now, weeds in no-tillage crops were mainly controlled with herbicides. To use the advantages of no-tillage in organic farming systems new tools have to be developed to maintain the competition of weeds at a low level. Living mulch systems are a possibility to implement no-tillage techniques without herbicides and, nevertheless, control weeds efficiently. For a better understanding of the complex interactions among weeds, cover plants and winter wheat under the cool and wet conditions of central Europe, a field trial was carried out in the Swiss midlands. Winter wheat (Triticum aestivum L. cv. Titlis) was direct drilled into living mulches of white clover (Trifolium repens L.), black medic (Medicago lupulina L.), and a mixture of both legumes. Total weed abundance was generally reduced with living mulches. In particular, densities of sowthistle (Sonchus spp.) and birdseye speedwell (Veronica persica L.) were significantly reduced when legumes were used as ground cover.