The portfolio model provides a new framework that enables farmers to make tradeoffs between the returns and risks of agricultural production. However, it has only been used in cost allocation among resources and in farmland allocation among crops at present. Thus, we conducted a portfolio model analysis based on an independent, mixed cross-section of data accounting for 1650 rural households in Minqin county, China, over a timescale of three years; the goal was to explore the feasibility and actuating extent of the portfolio model in optimizing the allocation of agricultural resources among crops other than farmland. The results showed that, by optimizing resource allocation among crops using a portfolio model, the return per unit resource of farmland, water, and labor increased by CNY 4.03 thousand per hectare, CNY 0.38 per cubic meter, and CNY 39.75 per day, without increasing risk, and with corresponding increases in use efficiency of 14.64%, 9.25%, and 13.55%, respectively, in the study area. Therefore, the portfolio model is a good tool for agricultural resource allocation optimization. Policy makers can manage agricultural resources according to their risk preference using this model. This study provides new insights into agricultural resource allocation and critical empirical evidence for return and risk management, as well as resource use efficiency improvement in agricultural production.

Under the condition of different endowment factors of herders and imperfect market mechanisms, grassland transfer can promote the redistribution and rational utilization of grassland resources, which has a crucial impact on herders’ livelihood. This study fully examined how the grassland rental market improves herders’ income and to what extent, using unbalanced panel data with 560 herder households in the Qinghai–Tibet Plateau pastoral areas. A fixed effect model was used as the baseline model. The instrumental variable approach and propensity score matching method were utilized to address the endogeneity problem and sample selection bias. Finally, the mediating effect model was used to analyze the path mechanism of grassland transfer in/out on herder income. The results showed that the total household income increased significantly after participating in grassland transfer. Grassland rent-in increased livestock income, and grassland rent-out increased non-livestock income. After correcting for the selection bias, the income effect of grassland transfer became larger. The grassland rent-in increased the livestock income by promoting production investment. Grassland rent-out increased the non-livestock income by promoting non-pastoral employment.

The rapid growth of farmland rental markets in China raises questions about the association of farmland rental and agricultural productivity. Although this issue has been extensively studied, the majority of studies have focused on yields and technical efficiency, with input use and cost efficiency receiving little attention. This study aimed to determine the statistical association of wheat and maize farmers’ farmland rental behaviors (renting land, not renting land and renting out land) and input use, and the consequent association of farmers’ farmland rental behaviors and cost efficiency. For this purpose, the linear regression model and stochastic frontier model were employed, based on a survey data of 419 wheat and maize farmers in 25 villages in five counties of Gansu Province, China. The study found that farmland rental enhanced productivity and sustainability of agriculture through transferring farmland from households with less productivity to those with high productivity, and it was also helpful to reducing the consumption of fertilizers and chemicals in agricultural production. The results suggest that replacing labor with machines is an important way to reduce production costs, and households specializing in agricultural production use more rational amounts of fertilizers and chemicals than those with low productivity. Thus, the machinery purchase policy in China should continue to give great benefit to farmers. In addition, the machinery purchase subsidization policy has achieved satisfactory results in China, and it could be a good reference for other developing countries. However, some efficiency loss was found in households that rented out their land, and policy makers need to pay some attention to these households.

As a consequence of the new strategy to boost productivity capacity and ensure food security, China’s farmland rental market is developing rapidly, and its impacts on agricultural productivity have been extensively studied. However, the impacts of farmland rental on food safety have not been considered. The aim of this study was to determine the causal effects of farmland rental on fertilizer and pesticide use in wheat and maize production and evaluate the potential effects of this activity on food safety. Survey data obtained from 900 households in eight counties in Gansu province were used in this study, and the propensity score matching (PSM) method was employed to solve selection bias problems with the data. The results showed that farmland rental significantly reduced fertilizer and pesticide use in wheat and maize production, implying a potential reduction in heavy metal contamination of food and drinking water as well as less pesticide residues-remaining in food and contamination of environment. Also, households renting land were more likely to adopt new agricultural technologies and management methods and to acquire more agricultural acknowledges and information than those not renting land and renting out land. Thus, farmland rental is a benefit to the application of new agricultural technologies and management methods, to rational use of agrochemicals, and finally to food safety and environmental conservation. Policies such as encouraging farmland rental, enhancing education of farmers, improving technological innovation, and providing better information transfer should help ensure not only “enough food” but also “safe food”.

Climate change and air pollution are intrinsically interconnected as carbon dioxide and air pollutants are co-emitted during fossil fuel combustion. Low-carbon policies, aimed at mitigating carbon emissions, are also anticipated to yield co-benefits for air quality; however, the extent to which regional low-carbon policies can effectively achieve significant reductions in air pollutant levels remains uncertain. In China, the implementation of the low-carbon city pilot (LCCP) policy has reduced carbon emissions, but further research is needed to examine its effectiveness regarding achieving air quality co-benefits. Adopting a difference-in-differences model with a 19-year national database of air quality, this study examines whether the LCCP policy improves air quality in China’s metropolitan areas and explores how these policy initiatives address their air pollution challenges. The results indicate that, following the implementation of the LCCP policy, the mean, maximum, and standard deviation of the AQI in pilot cities decreased significantly by 9.3%, 20.8%, and 19.8%, respectively, compared to non-pilot cities. These results suggest that the LCCP policy significantly improves air quality and provide evidence that this improvement is facilitated by advancements in green technology, industrial restructuring, and the optimization of urban planning and landscape design.