Suitability of Strip‐Tillage and Undersowing in Maize Crops to Control Runoff, Soil Erosion and Herbicide Loss: Field Trials and Modelling

ABSTRACT In Western Europe, the silt loam belt is highly vulnerable to erosion, especially in spring on fields cultivated with spring crops such as maize. Identifying conservation farming practices that reconcile agricultural production with soil and water protection is therefore critical. To this end, we evaluated the suitability of red fescue or white clover undersowing as well as strip‐tillage to control runoff, soil loss, and herbicide surface loss in maize under natural rainfall conditions. Results were compared to a sole‐maize control. The treatments were implemented in triplicate across six trial sites, distributed over three cropping seasons from 2021 to 2023. Weed control in the undersowing treatment proved particularly challenging due to herbicide constraints. Furthermore, no mitigation effect was observed on water, sediment, and herbicide surface flows, while maize yields were reduced by 11% on average compared to the control treatment. Although strip‐tillage also resulted in an 11% loss in maize yields on average, it significantly decreased runoff (−31%) and soil loss (−60%) compared to the control. Based on the measured runoff and soil losses for the control and strip‐tillage treatments, the process‐based CREHDYS model was calibrated using a parsimonious approach. It was then used to conduct scenario analyses across a range of soil, rainfall and slope conditions found across the Belgian loess belt. On average across all scenarios, pluvial flood hazard was reduced by about half. Modelling of soil losses in strip‐tillage proved insufficiently reliable, highlighting the need for improved characterisation of sediment fluxes in such systems. In spite of the disappointing results of undersowing in terms of yields and reduction in surface flows, future research could focus on other environmental benefits of this technique. For strip‐tillage, strategies should be investigated to promote its adoption by farmers as a stepping stone towards no‐till systems.