Soil carbon for carbon sequestration and trading: a review of issues for agriculture and forestry

This review looks at factors that may influence organic soil carbon and issues facing its inclusion in a carbon trading scheme in the future. A key factor contributing to climate change is excessive levels of greenhouse gases in the atmosphere and global efforts are focussed on both reducing our emissions of greenhouse gases and increasing the storage (sequestration) of atmospheric carbon. Soil, as an important part of the carbon cycle of the planet, has the potential to store carbon and contribute to mitigating greenhouse gases. In total, soils contain about 3 times more carbon than the atmosphere and 4.5 times more carbon than all living things. Hence a relatively small increase in the proportion of soil carbon could make a significant contribution to reducing atmospheric carbon. The amount of organic soil carbon that can be stored is influenced by a number of factors, including land use practices, soil type and climate. Increasing the amount of organic soil carbon may also improve soil health, providing added benefits to ecosystems and agricultural and forestry productivity. This review looks at factors that may influence organic soil carbon and issues facing its inclusion in a carbon trading scheme in the future. In order for organic soil carbon to be included in an enterprise-level carbon trading scheme, it must be measurable in an efficient and inexpensive way and at scales small enough to be applicable at the farm level. The review highlights areas where further information is needed.