Reducing tillage and herbicide use intensity while limiting weed-related wheat yield loss

Integrated weed management (IWM) promotes the combination of non-chemical techniques to achieve sustainable weed control while reducing the reliance on herbicides. However, IWM strategies reducing both herbicide and tillage intensity remain unsatisfactory, leading to weed-induced yield loss. In this study, five different IWM strategies were implemented for three years (2020–2022), aiming at reducing herbicide application across four tillage intensities while limiting weed-induced yield loss. These strategies were annual moldboard ploughing without herbicides (PL0H), annual moldboard ploughing with reduced herbicide use (PLHred), occasional moldboard ploughing with reduced herbicide use (PLredHred), shallow tillage without herbicides (ST0H) and no-tillage with reduced herbicide use (NTHred). Over the three years, averaged soil tillage intensity rating (STIR) and herbicide treatment frequency index (HFTI) ranged from 6 to 87 and from 0 to 1.6, respectively, and showed an inverse relationship. Reducing herbicides led to more mechanical weeding and reducing soil tillage led to more herbicide use. The effects of IWM strategies and years since implementation, on total weed and crop biomass, estimated weed and crop volume, weed density, weed species richness and grain yield were analysed in winter wheat. No differences in weed biomass, volume, or species richness were observed between IWM strategies over the years. Weed density increased only in PL0H between 2020 and 2022. Wheat grain yield varied by years but not among IWM strategies over time. Estimated weed-related yield loss was moderate in 2020. The feasibility and performances of such systems must be assessed over a long-term period to ensure their sustainability.