Climate Change Adaptation through the lens of farmland size: the role of government programs, economies of scale, and uncertain returns

The heterogeneity of different farmland sizes has been overlooked in the climate adaptation literature, yet it is crucial for identifying effective policy interventions to achieve national-scale climate resilience. Using U.S. Agricultural Census data from 2012, 2017, and 2022 aggregated by farm size groupings within states, we compare the temporal changes in adoption of three water-related climate adaptation practices (cover crops, tile drainage, and irrigation) across small, medium and large farms, individually. Specifically, we provide estimates of the role of multiple government programs and climate changes in shaping heterogeneous climate adaptation behaviors across farm sizes. Applying multilevel models within a Bayesian framework, we show that temporal changes of government programs and climate conditions correlate with temporal changes in adoption differently across farm sizes. For small and medium farms, insurance participation associates positively with adoption of cover crops and irrigation. Among large farms, federal programs correlate negatively with irrigation, while state programs and insurance are positively associated with cover crops. These results suggest the opportunity to enhance cover crops among small and medium operations by improving the distribution of insurance and state programs, where small farms often have low participation. Alternatively, crop insurance, and not climate, might be the major driver of irrigation expansion among smaller farms as a way to increase productivity and reduce premium subsidies. Finally, small farms’ adoption of irrigation and tile drainage shows uncertain or negative correlations with changing and uncertain climate, implying that diseconomies of scale might be limiting their adoption; meanwhile, uncertainty of returns under climate changes is preventing farms of all sizes from growing cover crops, specifically in the West for large and medium farms, and the Eastern regions for small farms. We conclude that encouraging the adoption of water-related climate adaptation practices may require adjusting current federal and local programs toward individualized farm-size policies.