Managing species dominance in cereal-legume intercrop systems

Weeds threaten crop productivity, while reliance on herbicides raises environmental and health concerns. Intercropping offers an alternative for sustainable weed suppression, particularly when component crops differ in competitive ability. However, such differences can also lead to competitive dominance by the stronger crop species, reducing the yield of its companion. To design intercrops for enhanced weed suppression without compromising yield, it is important to understand how species selection and spatial arrangements influence competitive dynamics. We conducted four field experiments (2022–2024) evaluating how species combination, mixing ratio, and spatial design influence dominance in cereal–legume intercrops under herbicide-treated and weed-infested conditions. Cereals showed superior light capture compared to legumes, which aligned with higher weed suppression but not necessarily with competitive dominance, indicating that strong weed suppression can be achieved without excessive legume suppression. Species choice strongly influenced competitive balance: rye severely suppressed legume yields, while other species combinations showed more balanced competitive relationships. In triticale-faba bean intercrops, reducing triticale proportion improved faba bean’s relative performance, with the 1:3 triticale:faba bean ratio achieving balanced yield contributions from both species. Wider row spacing reduced triticale’s competitive dominance but decreased total intercrop productivity. Under weed-infested conditions competitive dynamics shifted, with reduced triticale dominance and improved faba bean performance, suggesting that cereal–weed competition indirectly facilitates legume growth. These patterns demonstrate that thoughtful intercrop design can balance weed suppression with legume productivity, providing a viable approach to reducing chemical weed control while maintaining crop yields.