Effect of tillage and straw return on carbon footprints, soil organic carbon fractions and soil microbial community in different textured soils under rice–wheat rotation: a review

Measuring the influence of long-term agricultural tillage practices on soil organic carbon (SOC) is of great importance to farmers and policymakers. Different management practices affected SOC mainly at the soil surface level. The different fractions of SOC viz. total SOC, particulate organic carbon, soil microbial biomass carbon, and potentially mineralizable carbon, were reported to be strongly correlated over a diversity of soils and management systems. Frequent tillage deteriorates soil structure and weakens soil aggregates, causing them to be susceptible to decay. The mixing of residues/surface retention into the soil increases SOM mineralization due to greater exposure to microbial decomposers and optimal moisture and temperature. Increased efficiency of N fertilizers use can result in reduced carbon footprints of field crops, because the contribution of N fertilizers is 36–52% of total emissions while increased soil C sequestration reduces the carbon footprint, because the input carbon as CO2 from atmospheric is converted into the plant biomass and eventually deposited to the soil. Decreasing soil tillage integrated with crop residues retention can increases SOC and decreases carbon footprint, and the mixing of key agricultural practices could increase the crop yields, reduce the emissions and carbon footprint respectively.