Carbon sequestration in soils-A Review

Agricultural soils can be a source or sink for atmospheric CO₂ depending upon the management practices and land use patterns. Progressive increase in the concentration of GHGs since industrial era has created worldwide interest in identifying strategies to reduce concentration of these gases in the atmosphere. Carbon sequestration is an important technology for the maintenance of optimum CO₂ level in the atmosphere, which in-turn results in reducing the recent increase in atmosphericcarbon dioxide, contributing to global warming. Carbon stored in soilsis 2–4 times more as compared to that stored in the atmosphere and around 4 times that C stored in vegetation. The potential carbon sequestration in world soil is 0.4–1.2 Gt C/year. Therefore, it is understandable that the soil C sink has significant impact on sequestering CO₂. The objective of the paperis to review the potential of soils in sequesteringcarbon and mitigating the accelerated green house effects by changing agricultural management practices viz.conservation agriculture, organic agriculture, grasses/forages, proper grazing management, biochar and land use management. Significant amount of soil organic carbon (SOC) could be sequestered by changing conventional tillage to conservation tillage, its effect is noticeable only in long term rather than short term tillage practice. Legume-based crop rotation is more efficient in converting biomass C into soil organic C than the grass based. Rotational grazing improves grass quality and reduces the total amount of CO₂ released into the atmosphere. Another approach in sequestrating atmospheric carbon is biochar production and mixing it into soil.