Policy Implementation of Cultural-Tourism and the National Ecological Civilization Pilot Zone, Developing the Market, and Increasing Farmers’ Income

Based on county-level panel data from 2010 to 2023 covering 1991 counties, this study employs an Staggered Difference-in-Differences (DID) model integrated with double/debiased machine learning (DDML) and causal inference techniques. The objective of this paper is to assess whether and how the overlapping implementation of cultural-tourism integration (CTP) policies and the county-level National Ecological Civilization Pilot Zone (NECPZ) policy generates synergistic effects on rural residents’ income. The findings reveal that the policy overlap significantly promote farmers’ income. The synergy test shows that the synergy of these policies amplifies the effect of each individual policy and generates a “1 + 1 > 2” synergy effect. Mechanism analysis indicates that the policy overlap facilitates farmers’ income growth by enhancing the appeal and the development of the local tourism market. Heterogeneity analysis shows that the income-enhancing effect is more pronounced in counties with better public cultural services, stronger primary-level governance, and more advanced digital infrastructure. Furthermore, GDP growth rate, agricultural mechanization, and the industrial structure exert a nonlinear moderating effect on the policy effects. Based on these findings, the study proposes breaking down departmental and hierarchical barriers and building institutional synergy to transform ecological resources into economic value. According to local conditions, pilot projects should be prioritized in counties with stronger foundations, while guarding against the risk of diminishing marginal returns from excessive investment, so as to maximize policy synergies and promote fiscal efficiency.