Soil carbon in rangelands: what we don't know

The following post is based on a presentation from Garry Cook (CSIRO) at the CFI workshop in Darwin and Mataranka in 2012.

Soil carbon (or soil organic carbon) is contained within soil organic matter, which is made up of plant and animal materials in various stages of decay. It is particularly important for soil structure, provision of nutrients and biological processes.

Although Northern Territory soils tend to be inherently low in soil carbon, there may be potential to obtain non-Kyoto compliant credits by increasing the soil carbon in rangelands.




In general, conversion of native landscapes under agriculture, especially if conventional tillage has occurred, has resulted in a reduction in soil carbon. Improvements in management, such as enhanced rotations, adoption of no-till farming or increasing groundcover may lead to increases in soil carbon.

Modelling indicates that soil carbon should increase with improved land condition. However, at present there is little hard data on the soil carbon gains. Changes in soil carbon stocks tend to be difficult to detect due to high spatial variability and are likely to be affected by climatic conditions and natural disturbance. The difficulty in maintaining stocks during drought and fire may affect project development and a modelling approach to estimate longer term trends in soil carbon stocks may be required. Such an approach could also lead to the inclusion of soil carbon in Australia’s Kyoto accounts (i.e. Kyoto compliant credits). However, the complexity of types and longevity of organic matter in the soil may complicate modelling.

An application lodged in 2012 by CSIRO to fund research into soil carbon was unsuccessful. However, similar "Filling the research gap" applications were successful.

Acknowledgement: Garry Cook, CSIRO