Nikki P. Dumbrell

Greenhouse gas abatement costs are heterogeneous between Australian grain farms

Globally, agriculture is a significant contributor to greenhouse gas emissions. The environment (e.g., soils and climate) and management influence agricultural greenhouse gas emissions and the potential to reduce emissions. For agriculture to contribute to greenhouse gas abatement in the long term, it is important to identify low-cost mitigation actions that farmers can adopt. It is hypothesized that greenhouse gas abatement potential and the associated costs will differ substantially between environments in Australia. Seven alternative management scenarios were identified as both suitable for adoption across different grain growing environments in Australia and potentially able to provide greenhouse gas abatement. The Agricultural Production Systems Simulator was used to simulate these alternative management scenarios over a 25-year period and analyze the potential for Australian grain farmers, across contrasting environments, to increase soil organic carbon stocks and/or reduce nitrous oxide emissions. This analysis was paired with a whole-farm economic analysis to determine the implications of the different greenhouse gas abatement scenarios on farm profitability. Results from case studies in Australia’s three main grain growing regions demonstrate that significant heterogeneity exists in the biophysical potential and costs to reduce greenhouse gas emissions across locations. The maximum predicted abatement potential for the case study sites varied from 0.34 to 2.03 metric tons of carbon dioxide equivalents per hectare per year. In most simulations, greenhouse gas abatement came at a cost to farmers ranging from 0.11 Australian dollars (AUD) to more than 300 AUD per metric ton of abated carbon dioxide equivalent. This is the first study to explore the costs of mitigation including multiple greenhouse gases and grain farming case studies across Australia. These findings can inform the future development of effective climate change mitigation policies, which frequently use national default values in their design.