A Methodological Refinement for Evaluating Adoption of Priority Practices for Water Quality Improvement in Australia’s Great Barrier Reef

Efforts to improve Australia's Great Barrier Reef (GBR) water quality are constrained less by a lack of identified priority practices than by their persistent low and uneven adoption by farmers. Existing prioritisation and target-setting approaches largely emphasize biophysical effectiveness, with a limited focus on how farmers perceive and respond to proposed practice changes. This study introduces a methodological refinement of ADOPT (Adoption and Diffusion Outcome Prediction Tool) that embeds explicit, facilitated perspective-taking into adoption prediction. Rather than treating the use of ADOPT as a purely technical exercise, the approach uses expert-guided workshops in which Technical Working Groups respond to ADOPT questions from the perspective of the target population of farmers. This process generates baseline and ceiling adoption predictions that are grounded in farmers' decision-making realities. Using the priority practice of a dual-herbicide sprayer for sugarcane farming-a technology that applies different herbicides to different parts of each cane row, allowing some toxic residual herbicides to be replaced with less toxic alternatives-as a case example, we show that although perspective-taking is effortful and requires facilitation, it improves the credibility and realism of predicted adoption outcomes. The approach also clarifies which adoption influences are most constraining and where policy and programme interventions are most likely to be effective. This method provides policymakers with a transparent, cost-effective, and defensible basis for setting realistic practice-change targets, prioritising investments, and improving the effectiveness of GBR water quality programmes.