Soil organic carbon dynamics and land-use change

Soils contain more than twice the amount of carbon found in the atmosphere. Historically, soils have lost 40-90 Pg C globally through cultivation and disturbance. Current rates of carbon loss due to land-use change are about 1.6 ± 0.8 Pg C y^-1, mainly in the tropics. The most effective mechanism for soil carbon management would be to halt land-use conversion, but with a growing population in the developing world, and changing diets, more land is likely to be required for agriculture. Maximizing the productivity of existing agricultural land and applying best management practices to that land would slow the loss of, or is some cases restore, soil carbon. However, there are many barriers to implementing best management practices, the most significant of which in developing countries are driven by poverty and in some areas exacerbated by a growing population. Management practices that also improve food security and profitability are most likely to be adopted. Soil carbon management needs to be considered within a broader framework of sustainable development. Policies to encourage fair trade, reduced subsidies for agriculture in developed countries, and less onerous interest on loans and foreign debt would encourage sustainable development, which in turn would encourage the adoption of successful soil carbon management in developing countries.