Weed Community Dynamics Under Long-Term No-Till and Conventional Tillage in Nigerian Farming Systems

This study investigates weed community composition changes and weed seed bank dynamics under long-term no-till and conventional tillage management in Nigerian farming systems, providing evidence for informed weed management planning in conservation agriculture adoption contexts. The shift from conventional to no-till farming systems alters the weed community through changed seed bank stratification, weed emergence timing, and competitive environment. Understanding how weed communities evolve under no-till in Nigerian conditions is essential for developing appropriate weed management strategies as conservation agriculture expands. This study samples weed communities and seed banks from paired conventional and no-till plots established at least six years previously at research sites in Benue, Kaduna, and Ogun States representing major farming systems. Weed density, species composition, dominant weed biomass, and seed bank density at three soil depths are quantified in each system. Multivariate statistical analysis (cluster analysis and ordination) characterises differences in weed community composition between tillage systems. Herbicide efficacy comparisons assess the adequacy of current herbicide options for no-till weed management. Findings reveal that long-term no-till systems show significant shifts toward perennial grasses and geophytic weeds with deeper seed banks compared to annual grass-dominated communities in conventional tillage. Seed bank stratification with higher density near the soil surface in no-till reduces emergence of deep-germinating species. Total weed biomass is 18 percent higher in no-till without herbicide but equivalent with appropriate herbicide management. The study recommends adapted weed management plans specifically developed for no-till weed community composition in each major farming system.

Keywords: weed community dynamics, no-till, weed seed bank, conservation tillage, Nigeria.