Least-cost greenhouse gas mitigation on New Zealand dairy farms

A whole-farm model is used to assess least-cost methods of mitigating GHG-e from dairy farms of different production intensity across five diverse regions of New Zealand. Mitigation costs can be significant, with reductions in operating profit ranging between 2-8, 8-30, and 13-67 % for GHG-e reductions of 10, 20, and 30 %, respectively. Farms that lose proportionally less profit from mitigation are more-intensive farms characterised by higher stocking rates, nitrogen fertiliser application, and supplement feeding. This highlights the cost-effectiveness of de-intensification strategies (those associated with reducing input use) therein. All farms reduce stocking rate, decrease nitrogen fertiliser application, reduce supplement use, and improve reproductive management to meet GHG-e goals. In contrast, the adoption of loafing pads is highly uneconomic. Overall, this study highlights the importance of considering heterogeneity among farms when evaluating abatement activities.