How Can Cooperatives Drive Small-Scale Farmers to Achieve a “Carbon Reduction Effect” in the Planting Industry: Evidence from China

China is vigorously promoting agricultural energy conservation and carbon reduction and accelerating the transformation of traditional agriculture towards green development, which is a key measure adopted by the Chinese government to advance agricultural modernization. Based on the panel data of 30 provinces in China spanning 2006–2023, this paper systematically studies the impact of agricultural cooperatives driving small-scale farmers on carbon emissions in the planting industry by comprehensively applying linear regression, mediating effect, threshold effect, and spatial econometric models. Studies show that cooperatives have significantly reduced carbon emissions for small-scale farmers, with a stable “carbon reduction effect”, and this effect is most obvious in the eastern region, presenting a regional gradient characteristic of “east > central > west”. The differences between major grain-producing areas and non-major grain-producing areas are relatively small, indicating that their emission reduction effect has wide applicability. Mechanism analysis indicates that improvements in agricultural technology and rural land transfers are key pathways to achieving emissions reductions. Further findings reveal that exemplary cooperatives have a dual threshold effect: they may initially experience a short-term “carbon increase effect”, but as the organization matures, it turns into a significant “emission reduction”. In addition, the development of cooperatives in this region has a positive spillover effect on the carbon emissions of the planting industry in the surrounding areas. This study makes up for the deficiency of the existing literature in the mechanism of “organization-driven individual” promoting agricultural green transformation; it reveals the path of cooperatives promoting low-carbon agriculture through technological promotion and land integration, enriches the theoretical system of agricultural green transformation, and provides replicable practical references for developing countries to promote energy conservation and carbon reduction in agriculture.