Cover crops to secure weed control strategies in a maize crop with reduced tillage

Abstract To better understand the ability of cover cropsto control weedsin a maize crop(Zea mays, L.) grown with reduced tillage, four field experiments were set up from 2009 to 2014 in the western part of Switzerland. Ten non-wintering cover cropspecies were compared to a no cover cropcontrol in strip plot experiments including different weedingstrategies. The weedingstrategies included no or minimum tillagebefore maize seeding. Soil coverage by weedsat early maize stage (2–4 leaf stage) varied drastically between weedingstrategies and years. In most cases, cover cropsallowed to reduce the weedpressure compared to the no cover cropcontrol. The most efficient cover cropspecies varied from year to year, but niger ( Guizotiaabyssinica, (L.f.) Cass.), sunflower ( Helianthus annuus, L.), field pea( Pisumsativum, L.) and phacelia( Phacelia tanacetifolia, Benth.) gave the best overall results. Maize yield differed significantly between weedingstrategies only one year, with higher yield observed with minimum tillage. In some situation, cover cropscultivated in autumn still showed a significant impact on maize yield, with common vetch ( Vicia sativa, L.) as the most successful species. Interestingly, the effect of cover cropon weedcover and maize yield was not limited to the less intense strategy (no tillage). These results show that cultivating cover cropsbefore maize in this type of conditions is a promising method to help controlling weeds. In addition, cover cropsare known for providing multiple ecosystem services which could altogether improve the sustainability of croppingsystems on the long term.