Can soil carbon be the latest weapon in the global fight against climate change? Researchers at Curtin University have found that effective soil carbon management could be the key to combat greenhouse gas emissions and climate change.

Led by Professor Raphael Viscarra Rossel from Curtin’s School of Molecular and Life Sciences, the research project revealed that soil carbon is controlled by a range of factors that can vary at the local, regional and continental scales.

Soil carbon is both a source of carbon to the atmosphere as well as a potential sink. Its ability to store carbon that has been released into the atmosphere from other human activities makes soil an important weapon to fight climate change.

Rossel observed that a better understanding of the factors controlling soil organic carbon storage, its composition and its vulnerability to loss is needed to slow the accumulation of greenhouse gases and help mitigate global warming, adding that it can help maximise the potential capture and storage of atmospheric carbon in soil.

Employing a machine learning method, the research analysed more than 5500 sensor measurements of soil organic carbon components, the particulate, humus and resistant organic carbon fractions, which decompose at different rates.

While the research showed that climate, soil properties and elevation were the most important factors controlling soil carbon storage at the continental level, Rossel believes it is also important to study influential region-specific controls that affect the variability of organic carbon fractions and vulnerability.

Soil carbon modelling is undertaken at a range of scales using a variety of models for different purposes. Global climate models, for instance, can effectively use continental scale soil carbon estimates for global carbon budgeting; however, this approach cannot be extended to local management of soil carbon.

“Regionally, the effect of climate on soil carbon storage is dependent on interactions with soil properties, mineralogy and topography. In some regions, climate does not play a role,” Rossel said.

“This shows the need for localised assessments of soil carbon dynamics and a more effective approach to carbon management at local scales.

“This new knowledge has implications for us meeting the triple challenge of climate change, landscape restoration and food security. It also helps with the 4 per 1000 global initiative, which encourages farming practices that maintain or enhance organic carbon stocks in agricultural soil to ensure sustainable agriculture in the face of climate change.”