Effects of Policy Mixes for Conservation Tillage on Agricultural Green Total Factor Productivity: Evidence from Heilongjiang Province, China

Conservation tillage plays an important role in improving sustainable land use and maintaining food production. Using survey data from 261 agricultural producers in Heilongjiang Province, China, this study examines how conservation tillage policy mixes affect agricultural green total factor productivity (AGTFP). The slack-based measure (SBM) model incorporating undesirable outputs is employed to estimate AGTFP. A Tobit model with interaction terms is applied to analyze the independent and combined effects of three policy instruments: subsidies, regulations, and supporting services, and a mediating effect model is used to verify how these instruments work. The results indicate that: (1) the mean AGTFP value stands at 0.37, reflecting a generally low level of performance, with the largest improvement requirements observed in seed inputs (66.25%), machinery inputs (65.53%), and nitrogen emissions (61.55%); (2) subsidies, regulations, and supporting services all improve AGTFP, while the combinations of subsidies and services, regulations and services, and the full three-policy mix generate significant positive synergistic effects; (3) policy mixes facilitate AGTFP enhancement by increasing agricultural producers’ perceived value of conservation tillage technologies and reducing perceived risks. In particular, the interaction between regulations and supporting services significantly increased perceived value (β = 1.129, p < 0.01) and reduced perceived risk (β = −0.810, p < 0.01); (4) the effects of policy mixes are stronger for producers pursuing green production goals and for small-scale farmers. Based on these findings, the following recommendations are proposed: policy efforts should strengthen the coordination of subsidies, regulations, and services, linking training and inspection results to subsidy eligibility; address efficiency bottlenecks in seeds, machinery, labor, and nitrogen emissions; design differentiated policy packages for various farm types; and build a training system that includes at least two mandatory sessions per season and ties training outcomes to subsequent subsidies. This study contributes a policy mix perspective to the evaluation of AGTFP and provides empirical evidence for coordinated conservation tillage policy design.