Offsetting global CO2 emissions by restoration of degraded soils and intensification of world agriculture and forestry
2003
Lal, R.
Increase in atmospheric concentration of CO2 from 285 parts per million by volume (ppmv) in 1850 to 370ppm in 2000 is attributed to emissions of 270±30Pg carbon (C) from fossil fuel combustion and 136±55Pg C by land-use change. Present levels of anthropogenic emissions involve 6·3 Pg C by fossil fuel emissions and 1·8Pg C by land-use change. Out of the historic loss of terrestrial C pool of 136±55Pg, 78±12Pg is due to depletion of soil organic carbon (SOC) pool comprising 26±9Pg due to accelerated soil erosion. A large proportion of the historic SOC lost can be resequestered by enhancing the SOC pool through converting to an appropriate land use and adopting recommended management practices (RMPs). The strategy is to return biomass to the soil in excess of the mineralization capacity through restoration of degraded/desertified soils and intensification of agricultural and forestry lands. Technological options for agricultural intensification include conservation tillage and residue mulching, integrated nutrient management, crop rotations involving cover crops, practices which enhance the efficiency of water, plant nutrients and energy use, improved pasture and tree species, controlled grazing, and judicious use of inptus. The potential of SOC sequestration is estimated at 1–2Pg Cyr−1 for the world, 0·3–0·6Pg Cyr−1 for Asia, 0·2–0·5Pg Cyr−1 for Africa and 0·1–0·3Pg Cyr−1 for North and Central America and South America, 0·1–0·3Pg Cyr−1 for Europe and 0·1–0·2Pg Cyr−1 for Oceania. Soil C sequestration is a win–win strategy; it enhances productivity, improves environment moderation capacity, and mitigates global warming.
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