Weed suppression and maize yield influenced by cover crop mixture diversity and tillage

Abstract

The integration of cover crops into cropping systems has demonstrated significant potential for enhancing weed suppression, improving soil health, and reducing dependence on chemical herbicides. A three-year field study conducted in Slovenia between 2020 and 2023 aimed to quantify the seasonal competitive relationships between cover crop and weeds while also evaluating potential yield benefits for the subsequent maize crop. A randomized complete block design accounted for variations in soil tillage (conventional and conservation) and cover crop type (single species: oilseed radish and berseem clover; a simple five-species cover crop mixture; and a functionally diverse seven-species cover crop mixture). Oilseed radish imposed the highest level of competition against weeds within the first four weeks post-sowing. The highest levels of weed suppression across years and tillage practices were observed with oilseed radish and the simple cover crop mixture (81–85 %). The functionally more diverse cover crop mixture was not more productive or weed suppressive than other cover crops neither did improve the level of weed control. The weed suppression level not closely linked to cover crop biomass production, suggests that rapid early growth may be more relevant functional trait for cover crop weed suppression capabilities. Maize yields were insignificantly improved with berseem clover and the most productive simple cover crop mixture by 0.7 t ha ⁻¹. The present study confirms the importance of cover crops as a key non-chemical weed management strategy for diversification. However, it also indicates the need for developing trait-based cover crop mixtures to further enhance cover crop-weed competition and main crop yield outcomes under specific resource availability, management practices, and desired ecosystem services.