Get reliable rangeland science

To develop sustainable sheep production, there is a need to stack multiple mitigation interventions on the one land parcel, such as grazing management associated with soil organic carbon (SOC) accrual and feed additives for enteric methane reduction. The study, thus, aimed to investigate trade-offs between farm profit and greenhouse gas (GHG) emission reduction associated with those interventions. We used soil carbon data measured in a long-term field experiment in New South Wales and data of net emissions (associated with using different feed additives) on two sheep farms (440 ha and 3786 ha), representative for small-scale and larger-scale farms. Then, a mixed-binary nonlinear programming model was applied to identify combinations of grazing management and feed additives to maximise farm profit and minimise net GHG emissions. The results of both farms indicated that the most appropriate grazing management and feed additives varied depending on farmer's objective was profit or emission reduction or both. If profit was key goal, combination of multi paddock-fast rotation-high stocking rate and 1% walnut shell biochar would be adopted. In contrast, 15 paddock-slow rotation-low stocking rate and flexible grazing stacking with 0.2% Bovaer would be considered to minimise net emissions. If the objective was to maximise profit and minimise net emissions simultaneously, results of adopting multiple grazing management varied depending on farm size. The small-scale farm tended to adopt 15 paddock-slow rotation-low stocking rate and flexible grazing, while the larger-scale farm implemented 1 5 paddock-fast rotation-high stocking rate and flexible grazing. Furthermore, carbon price was a driver of farmer's decisions on mitigation interventions. The larger-scale farm would change to adopt 15 paddock-slow rotation-low stocking rate and flexible grazing when carbon price was equal or more than $AU50/tonne CO2-equivalent. Thus, policies and legislative process relevant to increases in carbon price should be considered.