What Really Drives Agri‐Environment‐Climate Measures' Adoption? Mandatory Requirements, Behavioral Traits, and Structural Factors in the CAP Green Architecture

To increase farmer adoption of green practices, the EU Common Agricultural Policy includes both mandatory (conditionality) and voluntary instruments (eco‐schemes–ECS– and more demanding, multi‐annual agri‐environment‐climate measures –AECM–). Building on the experiment of Barreiro‐Hurle et al. (2023), which focused on eco‐schemes, this paper analyses farmers' stated willingness to voluntarily adopt AECM. Using a framed experiment with 600 farmers in Spain, Germany, and Poland, we compared two policy interventions—higher mandatory environmental requirements and an equivalent reduction in income linked to CAP direct payments—and varied their intensity. Higher mandatory environmental requirements and an equivalent income reduction reduce the willingness to voluntarily adopt AECM. We also find a positive conditional association between the intensity of ECS adoption and the willingness to adopt AECM, suggesting potential spillover effects. We further show that behavioral factors, particularly perceived fairness of compensation, environmental concern, confidence in the environmental program, and CAP entitlement, explain substantially more variation in willingness to adopt AECM than standard structural and socio‐demographic characteristics (farm and farmer features). These results have implications for the upcoming envisaged CAP green architecture.