Environmental concerns compel us to reduce agricultural chemical inputs such as herbicides and mineral fertilizers, particularly nitrogen. Reduced herbicide use may increase weeds and reduced mineral fertilization may limit nitrogen resources. Thus, crop-weed competition for nitrogen may increase. Weeds with high nitrogen nutrition requirements are often hard to manage. They could be disadvantaged by driving crop-weed competition through an adequate choice of crop species/varieties (according to their nitrogen nutrition traits) and/or adaptation of nitrogen fertilization (rate, date, straw burial or export). This study aimed to identify which crop traits and nitrogen fertiliza tion options can reduce weed harmfulness while maintaining crop production over the years. A maize monoculture from Aquitaine (France) was simulated over 10 years and 5 weather repetitions using FlorSys1. This process-based model simulates crop growth and weed dynamics over the years with a daily time step from inputs describing cropping system and pedoclimate and from species traits. We simulated many combinations of nitrogen fertilization (dates and rates, straw burial vs export) and initial soil organic nitrogen content with three maize varieties (one actual V1 and two virtual named V2 and V3) differing by their trait values related to nitrogen nutrition. The effects of fertilization, initial soil organic nitrogen supply and maize variety on potential yield and weed (dis)service indicators were studied. A sensitivity analysis revealed that maize variety, nitrogen rate and initial soil organic nitrogen content affected the indicators the most. Nitrogen date and straw burial vs export affected them the least. Compared to the V1 maize variety, in average, V2 improved potential yield, weed services (weed species richness, bee food offer) and decreased disservices (yield loss due to weeds, weed seed production). Variety V3 had the opposite effect. Depending on their traits related to nitrogen nutrition, maize varieties reacted differently to fertilization techniques. For V1 and V2 to a lesser extent, increasing nitrogen rate increased potential yield, species richness, decreased weed seed production and bee food offer. It was the opposite for V3. Increasing nitrogen rate decreased yield loss for each variety, it was stronger for V1 and V2 than for V3. Interestingly, an increase of initial soil organic nitrogen of 50 kg/ha decreased potential yield by 0.5 to 1 q/ha depending on the variety. Further simulations applying optimization algorithms will be carried out to identify nitrogen dates and rates that maximize yield, bee food offer and minimize yield loss. 1Colbach N, et al. (2014), Weed Research, 54: 541- 555. https://doi.org/10.1111/wre.12112