Application of circular economy principles to pastoral farming: Development of an assessment framework

Context: Circular economy principles are being adopted to design out waste, use resources more efficiently and maintain ecosystem health. Aims: This study developed a framework to assess the ‘circularity’ of pastoral farms, using a New Zealand dairy farm as a case study. Methods: Key resource inputs and environmental impacts to assess for the farming system were determined. Nitrogen and phosphorus flows were assessed using the OVERSEER® model, to then determine their circularity on the basis of the material circularity indicator. Life-cycle assessment was used to determine the carbon footprint and fossil fuel depletion associated with the farm. Single-use plastic disposal was calculated on the basis of farm purchases and end-points of packaging. Key results: MCI circularity scores were 0.46 for nitrogen, 0.48 for phosphorus and total circularity 0.46, which could be improved by focusing on reducing the high rates of mineral fertiliser use and large losses of nitrogen to water and the atmosphere. Although the farm’s cradle-to-farm-gate fossil fuel resource depletion footprint (1.16 MJ/kg fat- and protein-corrected milk) was low compared with other New Zealand and European dairy farms, its carbon footprint of 0.85 kg carbon dioxide-equivalent/kg fat and protein corrected milk was high for New Zealand, with enteric methane emissions and inputs of supplementary feeds being the major sources. Plastic waste was a minor source of waste compared with nutrients, but the key sources were identified. Conclusions and implications: This framework could be used and adapted to assess the circularity of nutrients in pastoral farming systems and help identify key areas to reduce the depletion of critical resources and negative environmental impacts. Further development and testing are required for a range of farming systems.