The excessive use of fertilizer has resulted in serious environmental degradation and a high health cost in China. Understanding the reasons for the overuse of fertilizer is critical to the sustainable development of Chinese agriculture, and large-scale operation is considered as one of the measures to deal with the excessive fertilizer use. Under the premise of fully considering the resource endowment and heterogeneity of large-scale farmers and small-scale farmers in production and management, different production decision-making frameworks were constructed. Based on the 300 large-scale farmers and 480 small-scale farmers in eight provinces of northern China wheat region, we analyzed the optimal fertilizer use amount and its deviation as well as the influencing factors of small-scale and large-scale farmers, then further clarified whether the development of scale management could solve the problem of excessive fertilizer use. The empirical results show that: (1) both small-scale farmers and large-scale farmers deviated from the optimal fertilizer application amount, where the deviation degree of optimal fertilizer application of small-scale farmers is significantly higher than that of large-scale farmers, with a deviation degree of 35.43% and 23.69% for small and large scale farmers, respectively; (2) not all wheat growers in North China had the problem of excessive use of chemical fertilizer, as the optimal level of chemical fertilizer application in Heilongjiang and Inner Mongolia are 346.5 kgha⁻¹ and 335.25 kgha⁻¹, while the actual fertilizer use amount was 337.2 kgha⁻¹ and 324.6 kgha⁻¹, respectively; and (3) the higher the risk aversion level, farmers tended to apply more fertilizer to ensure grain output. Therefore, increasing farm size should be integrated into actions such as improving technological innovation and providing better information transfer to achieve the goal of zero-increase in Chinese fertilizer use.

The interlinked insurance and credit contract is an emerging model of agricultural insurance in China. However, the development of interlinked insurance and credit contract and farmers’ demands for it are poorly understood. Based on the wheat farmers on the Loess Plateau in China, a field experiment is employed to obtain dynamic choice data from 415 farmers. We empirically analyzed the inhibitory effect of credit constraint on farmers’ adoption behavior of innovative seeds and also explored the heterogeneity of farmers’ innovative seeds adoption due to the availability of interlinked insurance and credit contract. The results illustrate that credit constraint can hinder farmers’ innovative seeds adoption significantly, and interlinked insurance and credit contracts can encourage farmers to adopt innovative seeds effectively by dispersing natural risks and alleviating credit rationing. Further, constrained by low education levels in China’s rural areas, providing interlinked insurance and credit contract to farmers is not beneficial to enhance farmers’ innovative seeds adoption. In addition, farmers who are relatively poor may underestimate the benefits of innovative seeds at the beginning of planting, making their adoption behavior have some delayed effect. This research provides a new perspective for promoting the spread of innovative technology in rural areas.