Sustainable Weed Management in Conservation Agriculture: A Critical Synthesis of Ecological Processes, Diversified Tactics and Herbicide Stewardship

Abstract

Conservation agriculture is built on minimal soil disturbance, permanent soil cover and crop diversification, yet the reduction of tillage removes a historically important weed-control operation and can expose production systems to new ecological and evolutionary pressures. This critical narrative review evaluates how weed management can remain agronomically effective while preserving the soil, resource-use and resilience objectives of conservation agriculture. Peer-reviewed evidence was selected from accessible scholarly databases and indexes for the period 1 January 1990 to 9 June 2026, with earlier or later-dated records excluded from the evidence window and seminal concepts retained only when necessary. The synthesis focuses on weed seedbank redistribution, residue-mediated emergence, rotational diversity, cover crops, crop competitiveness, herbicide stewardship, strategic soil disturbance, precision interventions and adoption trade-offs. The evidence indicates that no-tillage does not have a uniform effect on weed pressure; outcomes depend on seedbank history, species traits, residue amount and persistence, crop sequence, herbicide programme and prevention of seed return. Cover crops and diversified rotations can reduce weed emergence and shift selection pressures, but their effects are variable and rarely sufficient as stand-alone control. Conversely, herbicide-intensive no-tillage can stabilise short-term control while accelerating resistance risk and, in severe cases, undermine continued conservation tillage. The strongest evidence supports integrated systems that deliberately combine preventive, cultural, biological or physical filters with judicious herbicide use, rather than treating either tillage or herbicides as binary choices. Strategic, infrequent disturbance and site-specific technologies may have roles where weed escapes threaten long-term system function, provided that soil-quality costs are measured rather than assumed. Sustainable weed management in conservation agriculture is therefore best understood as a dynamic system-design problem: management must suppress current weeds, reduce future seed rain, diversify selection pressures and protect the ecological functions that motivate conservation agriculture in the first place.