The need to increase soil carbon stocks to contribute to mitigating agricultural greenhouse gas emissions is appreciated widely in the farming community, with perceived associated benefits of improving soil quality and productivity. Yet, despite growing attention, there is no firm evidence in our national inventory that changes in soil carbon stocks are occurring. With such high uncertainty, policy makers are not able recommend incentives for farmers and land use managers to measure and monitor changes in soil carbon stocks, so there is little progress towards goals to increase stocks.

Barriers to reducing uncertainty in measuring and predicting changes in soil carbon stocks are often identified as a critical lack of scientific data, high spatial variability, very low rates of change, variability among soils and climate and complexity in interpreting and modelling  the processes regulating carbon cycling. While considerable progress in the last decade has helped to address these knowledge gaps, the emphasis has been largely limited to management practices using conventional and intensive grazing practices.

Soil carbon stocks are dependent on spatial variability in soil mineralogy, climate and carbon inputs and losses. More specifically, carbon stocks are regulated by carbon inputs from plants and animals, their incorporation into soil organic matter, access for microbial decomposition and stabilisation into aggregates. The way forward to better understand and forecast opportunities for gains in soil carbon stocks must address the impacts of management practices on these processes to identify the critical control points. Management beyond conventional practices, such as grazing intensity and frequency, may provide insights to overcome some of these constraints and lead to novel ways to increase soil carbon stocks. A modelling framework is critical to explore the impacts of management options on soil carbon stocks and associated trade-offs.
