Environmental regulation is an important means of agricultural governance of agricultural nonpoint source pollution, and environmental supervision, as an important supplement to it, plays a key role in pollution governance. The relationships between environmental regulation and environmental supervision and the pollution of agricultural facial sources are of great theoretical and practical significance in achieving ecological livability and governance effectively, optimizing the theory of environmental separation, and promoting green development in agriculture. A theoretical model between environmental regulation and environmental supervision and the behavior of farmers‘ facial source pollution was constructed based on risk expectation theory, the fertilizer pollution equivalents during maize cultivation were estimated using the data of Maize Cultivation in each province of China from 2006 to 2018, and the relationships between environmental regulation and environmental supervision and agricultural non-point source pollution were analyzed by the dynamic panel model and the threshold effect model.
The study found that: firstly, fertilizer pollution equivalents increased year by year with corn planting, and in addition to planting benefits, the increase in production costs would also exacerbate fertilizer pollution through interelement substitution; secondly, the impacts of environmental regulation on the pollution equivalents of maize fertilizers are inverted U-shaped, and reasonable environmental regulation is helpful to effectively restrain the growth of agricultural non-point source pollution; thirdly, the environmental supervision will linearly regulate the inverted U-shaped relationship between environmental regulation and agricultural non-point source pollution, and strengthen the inhibitory effect of environmental regulation on pollution growth; fourthly, the impacts of environmental supervision on agricultural facet source pollution will exhibit two threshold characteristics as the intensity of environmental regulation changes, from insignificant effects to promoting effects, and turn to inhibiting effects after surpassing the second threshold. To propose differentiated and environmental supervision measures against regional environmental regulation intensity, strengthening environmental regulation, then separating the two-step go and conquer pollution model of regulation and regulation.