Carbon sequestration in soil.

Abstract

Abstract Carbon (C) sequestration in soil implies transfer and secure storage of atmospheric CO 2 into the soil organic carbon (SOC) pool as recalcitrant humus/biochar and into the soil inorganic carbon (SIC) pool as secondary carbonates. Its importance lies in the urgent need to offset increases in atmospheric enrichment of CO 2 (from 280 ppm in 1750 to 385 ppm in 2008) and its benefits to agronomic yield and soil quality. The soil C sink capacity, created by historic land use and soil degradation, is estimated at 78±12 Pg or 10-60 Mg/ha (Lal, 1999). Principal strategies of SOC sequestration involve: (i) restoration of degraded/desertified soils through conversion to a perennial land use, and (ii) adoption of recommended management practices including no-till farming, manuring, agroforestry and use of biochar as a soil amendment. The mean rate of C sequestration is 300-500 kg/ha/yr for SOC and 2-10 kg/ha/yr for SIC. Accelerated soil erosion is a net source of atmospheric CO 2 and must be effectively controlled. Soil C sequestration is also enhanced by adoption of nanotechnology, biotechnology, information technology and trading of C credits. Avoidance of deforestation, and afforestation of degraded/desertified soils are cost-effective and have a large potential to offset emissions, influence the global C cycle and stabilize the atmospheric CO 2 . Soil C sequestration is a win-win-win strategy because it advances food security, improves the environment and mitigates global warming.