These files contain data that Menalled et al. (2022) used to test the effects of crop density and mulch biomass on weed suppression and community assembly. The data was generated through a field experiment replicated for four site-years. In each site-year, soybean was planted at five rates from 0 to 74 seeds m-2, and five cereal rye mulch levels were established from 0 to 2 times the ambient cereal rye biomass within each site-year for 25 unique treatments. All treatments were replicated in four blocks for 100 plots per site-year. Approximately 15 weeks after soybean planting, weed biomass, soybean density, and mulch biomass were sampled in each plot. Changes in weed biomass and species abundance were used to assess weed suppression and community composition. We assessed treatment effects on weed life cycle, emergence timing, seed weight, height, and specific leaf area using trait data for each species. Results show that multi-tactic weed management can enhance weed suppression and promote the management of diverse weed functional groups. All analyses and results are reported and discussed in Menalled et al. (2022): “Cereal rye mulch biomass and crop density affect weed suppression and community assembly in no-till planted soybean.”