Soil Carbon Sequestration and Greenhouse Gas Dynamics in Sub-Tropical Farmlands: An Integrative Review

Abstract

Global atmospheric loading of greenhouse gases (GHGs) is intensifying  at measurable annual rates: carbon dioxide (CO2) at 0.5%, methane (CH4)  at 0.6%, and nitrous oxide (N2O) at 0.25 ppbv yr-1. Farming operations  collectively account for roughly 20% of this emission burden, and land-use  transformations—especially forest clearance—add another 14% to the total.  Among the practices most responsible for carbon release from managed  soils are tillage-based soil disturbance, agrochemical inputs, open field  burning of harvest residues, and exportation of crop biomass. Cumulative  land degradation since the advent of agriculture has eliminated an estimated  55–100 Pg from the global soil carbon pool and 100–150 Pg from terrestrial  biotic stocks. Transitioning to scientifically guided management can restore  soil organic carbon (SOC) and rebuild degraded land productivity. Under  unmitigated warming scenarios, global crop production could fall by a  quarter overall, and rain-fed cropping systems—which sustain the world’s  most food-insecure populations—could face yield losses approaching 50%.  Marginal and smallholder farmers, operating on limited land and capital,  face heightened exposure to these disruptions. Concurrent declines in crop  yields and freshwater accessibility are anticipated as thermal regimes shift  and seasonal precipitation becomes less reliable. This review synthesizes  current understanding of SOC behavior under climate pressure and makes  the case for scientifically robust policy frameworks that strengthen irrigation  systems and safeguard water resources. Decarbonizing the global energy base  remains the definitive long-run solution, but soil-based carbon sequestration  serves as an indispensable near-term strategy during the transition.