杜 聖一

ABSTRACT Agricultural methane emissions represent a significant contributor to global climate change, with irrigated rice cultivation being one of the primary sources. Despite the availability of effective mitigation technologies, their adoption often remains limited due to behavioural and institutional constraints. Water management practice that extends drainage periods during cultivation can curb methane emissions from irrigated rice at low cost, yet uptake among Japanese farmers remains modest. We surveyed 2219 rice producers in Shiga Prefecture using a labelled choice experiment that embedded two behavioural nudges (social norm and loss aversion) and one informational boost (knowledge enhancement), presented with or without a reminder. Farmers most favoured a 7‐day drainage extension. Social‐norm messages did not robustly shift adoption intentions, but loss‐aversion and knowledge enhancement paired with reminders increased the probability of choosing water management practice by 5–10 percentage points, particularly when financial incentives were modest. The added value of nudges and boosts faded once subsidies approached prevailing ceiling levels, suggesting diminishing marginal returns to stacking instruments. These findings suggest that timely, low‐cost behavioural interventions can effectively complement agri‐environmental payments in resource‐constrained settings, providing a scalable and context‐sensitive strategy to accelerate the adoption of climate‐smart rice practices.

As global warming worsens, there is a growing need to reduce emissions of methane, a greenhouse gas. In agriculture, a water management method called alternate wetting and drying (AWD) has proven effective in mitigating methane emissions from paddy fields. It is, therefore, advisable to disseminate it efficiently. This study was conducted in Shiga Prefecture, Japan, to determine what influences AWD adoption behavior and examine the effectiveness of human networks in promoting AWD. Spatial statistical methods, including Moran’s I and Global G* and the spatial probit model, were employed for the purpose. The analysis results indicate that the behavior of surrounding farmers, which constitutes a spatial factor, influences that of the individual farmers. Moreover, farmers who acquire and use data, those with large-scale production, and those who mainly sell paddy rice tend to implement AWD, whereas corporate-managed farms do not. Therefore, to more efficiently improve the AWD implementation rate in Shiga Prefecture, this study makes several recommendations. Farmers’ active information sharing and technology exchange should be leveraged to strengthen networks and promote best practices for AWD dissemination. Advancing agricultural digitalization and data utilization is crucial, particularly by reducing digital equipment costs and securing technical personnel through public investment. Additionally, the approach toward corporate entities in AWD dissemination should be reconsidered, with market incentives playing a role. Lastly, promoting larger farmland parcels and increasing large-scale management farmers who are motivated to adopt AWD is essential. These strategies constitute this study’s original contribution.