In this study, we explore the impact of "Nudge" and "Boost" methodologies on mitigating methane emissions from rice cultivation, a significant contributor to global greenhouse gas emissions. Through a cluster randomized control trial conducted in Japan, we assess whether strategic informational campaigns, incorporating these behavioral insight, can enhance the adoption of a prolonged mid-season drainage period, which can lower methane emissions from rice paddies. Our experimental results show notable differences in the effectiveness of basic communications from the local government as before (Control group) versus those enriched with social comparison messaging focusing on methane emission from paddy fields (Nudge). Specifically, we find a clear positive effect of social comparison messaging for farmers participating in community-based agriculture. Furthermore, our research indicates that targeted technical guidance (Boost), addressing prevalent concerns about altering traditional farming methods, significantly sways farmers' future intentions toward methane-reduction techniques. The study underscores the importance of combining nudges, which subtly alter the external choice architecture, with boosts that empower farmers' decision-making capabilities and counter cognitive biases, to effectively steer behavior towards environmentally sustainable practices.