In China, air pollution, especially fine particulate matter (PM2.5) pollution, has become increasingly serious with the rapid economic growth that has occurred over the past 40 years. This paper aims to introduce PM2.5 pollution as a constraint in the environmental efficiency research framework through the use of panel data covering the Chinese provinces from 2001–2018. PM2.5 environmental efficiency is measured with the slack-based measure (SBM)-Undesirable-variable returns-to-scale (VRS) model, and the results show that the average PM2.5 environmental efficiency score is 0.702, which indicates inefficiency, and is U-shaped over time. The PM2.5 environmental efficiency scores are unbalanced across the eight regions and 30 provinces of China. Additionally, the relationship between PM2.5 environmental efficiency and its influencing factors is examined with a tobit model, and the empirical findings indicate that the relationship between economic development and PM2.5 environmental efficiency is an inverted U, which is the opposite of the traditional environmental Kuznets curve (EKC). In addition, technological innovation, trade dependency, and regional development each have a significantly positive effect on PM2.5 environmental efficiency. However, environmental regulations, the industrial structure, and population density have significantly negative effects on PM2.5 environmental efficiency. Finally, this paper fails to prove that foreign direct investment (FDI) has created a PM2.5 “pollution haven” in China.

The comprehensive reform of agricultural water prices is an important policy for promoting the high-quality sustainable development of agriculture and ensuring national water security. In this study, based on farmer survey data from different water price policy implementation areas in the oasis–desert transition zone of the Heihe River Basin (HRB), crops are divided into high-water-consuming crops and low-water-consuming crops based on the average water consumption per hm². The content of this study consists of two main parts: first, the study explores the response of farmers to different agricultural water price policies by comparing the impact of uniform water price and tiered water price policies on their planting structure. Second, it studies the areas where the tiered water price policy is implemented to verify the impact of price signals on farmers’ production decisions. The results show that, compared with the uniform water price policy, the implementation of the tiered water price policy will significantly reduce the proportion of high-water-consuming crops planted when other conditions remain unchanged. Under the tiered water price policy, the increase in water prices will reduce the proportion of farmers planting high-water-consuming crops, but the difference is not significant. This result reveals that when the opportunity cost of irrigation water increases, farmers will increase the proportion of low-water-consuming crops. The findings also indicate that a higher educational level, improved land inflow, the number of crop types, and satisfaction with the current subsidy policy will help increase the proportion of low-water-consuming crops. However, an increase in the family-cultivated land area will reduce the area of low-water-consuming crops.

The intensive cultivation of agricultural land impacts crop production efficiency. In this study, the technical efficiency of rice production (TERP) in Jiangsu Province was measured by constructing an output-oriented DEA–BCC model on the basis of multiobjective moderate-scale farmland operation using the China Land Economic Survey (CLES) data from Nanjing Agricultural University spanning 2020 to 2022. We then use a panel Tobit model and fixed effect panel model to analyze the impact of the scale of contiguous plots (SCP) on the TERP, rice land productivity (RLP), labor productivity (LP) and cost–profit ratio (CPR). The results show that the primary term in the SCP had a positive and statistically significant effect on the TERP, RLP, and LP at significance levels of 5%, 1%, and 10%, respectively. Moreover, the quadratic term in the logarithm of the SCP had a negative effect on these three metrics, with statistically significant effects observed at the 10%, 1%, and 5% levels, respectively. Although a similar inverted U-shaped relationship is noted between the SCP and the CPR, it lacks statistical significance. This finding indicates that the relationship between the SCP and agricultural production efficiency for rice farmers has evolved or is evolving into an inverted U-shaped pattern. Contiguous plots that are either too large or too small are detrimental to enhancing production efficiency. Finally, by employing threshold modeling techniques, the results indicate that the SCP threshold of approximately 0.49 hectares is optimal for improving the TERP, RLP, and LP. Moving forwards, adopting a strategy of moderate-scale agricultural operations is essential for China to achieve agricultural modernization and ensure national food security.