Role of Cover Crops in Mitigating Greenhouse Gas Emissions in Agricultural Systems

Abstract

Agriculture is a significant contributor to global greenhouse gas (GHG) emissions, particularly carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). At the same time, it offers viable pathways for climate change mitigation through sustainable land management. This systematic literature review evaluates the potential of cover crops non-harvested plant species typically grown during fallow periods to reduce GHG emissions and support climate-smart agriculture. Cover crops influence GHG dynamics through multiple mechanisms, including carbon sequestration, biological nitrogen fixation, and reduced nitrate leaching. They also improve soil health by enhancing organic matter content, stabilizing soil structure, conserving water, and supporting beneficial microbial activity. Drawing from 80 peer-reviewed studies selected from an initial pool of 250, the review categorizes cover crops into leguminous and non-leguminous types. Legumes, such as clover and vetch, fix atmospheric nitrogen, decreasing the need for synthetic fertilizers and associated N₂O emissions. Non-leguminous species like rye and radish scavenge excess nutrients and improve carbon storage. Despite strong empirical support for their environmental benefits, the effectiveness of cover crops varies by species, soil type, climate, and management practices. In some cases, cover crops can even increase N₂O emissions under poorly drained or mismanaged conditions. Adoption of cover crops remains uneven, particularly in the Global South, due to financial, technical, and institutional barriers. Constraints include limited seed access, labor shortages, and lack of policy incentives. This review identifies key research gaps in understanding long-term effects, species mixtures, and cover crop performance under future climate scenarios. To scale adoption and maximize climate benefits, future efforts should focus on improving predictive models, expanding farmer training, and enhancing policy and financial support. Overall, cover crops present a promising, nature-based strategy for reducing agricultural emissions while enhancing soil health and resilience in the face of climate change.