Conservation Tillage for Climate Change Mitigation – The Reality

Conservation tillage as part of the solution to mitigate climate change effects and to ensure sustainable agriculture, was initially promoted to reduce soil erosion and improve soil organic matter content and water storage. The advantages of conservation tillage practices over conventional tillage include (1) reducing cultivation cost (2) allowing crop residues to act as an insulator and reducing soil temperature fluctuation (3) building up soil organic matter, and (4) conserving soil moisture. The conservation tillage practices result favourable changes in soil physical properties, such as bulk density, water holding capacity, pore size distribution, and aggregation. Stratification of soil organic matter and differences in nutrient distribution has also been observed in long-term conservation tillage systems. Conservation agriculture changes soil properties and soil processes compared to conventional agriculture. These changes can, in turn, affect the delivery of ecosystem services, including climate regulation through carbon sequestration and greenhouse gas emissions, and regulation and provision of water through modification in soil physical, chemical and biological properties. The benefits of conservation tillage in climate change mitigation primarily come from increased soil C sequestration. However, there are conflicting reports to this effect. Hence, this review addresses the potential and limitations of conservation tillage for soil carbon sequestration and trace gas fluxes and the possible mechanisms involved.