# Mapping Abandoned Cultivated Land in China: Implications for Grain Yield Improvement
Influenced by the changes in social and economic factors brought by urbanization and industrialization, cultivated land in developed countries and regions, such as Europe, America, Australia, and Japan, has been gradually abandoned to transition into grassland [29; 30; 31; 32], while in developing countries with rapid industrialization and urbanization, the abandonment of cultivated land is mainly due to the regulatory failure of the land management policy system and the development of agricultural technology [33; 34; 35; 36]. It can be found that existing studies on abandoned land in developed countries or regions. From the perspective of the natural conditions, the studies mainly focus on the mountainous areas with complex terrain and poor agricultural production conditions, while there are no comprehensive studies in the regions with significant regional differences in natural conditions, social and economic development, institutional policies, and other factors on a large scale. In addition, there is a lack of overall judgment on the issue of cultivated land abandonment in developing countries that are undergoing rapid socioeconomic changes and have more prominent conflicts between humans and land, which leads to relatively weak decision support for different regions. With the rapid development of industrialization and urbanization in China, the phenomena of rural labor transfer, non-agriculturalization of cultivated land, and cultivated land abandonment have become increasingly serious. Compared with other countries, China has a large population and significant disparities in regional development. Cultivated land generally shows the characteristics of poor quality, low production levels, less cultivated land per capita, and large areas of sloping land [37; 38]. Cultivated land plays an extremely important role in food security, social stability, ecological construction, etc. According to the statistics, there is continuous growth of agricultural land in China being abandoned and idle, and the contradiction between people and the land has become more prominent [1; 5]. Therefore, it is of great significance for ensuring food security, maintaining the ecological environment [39; 40], and improving agricultural development and sustainable utilization of land resources to accurately grasp the overall characteristics and distribution rules of abandoned cultivated land in China and to formulate effective policies to curb the abandonment of farmland under the new situation. Furthermore, although some scholars have analyzed the regional distribution of abandoned land in China, most of the data sources are based on survey data and meta-analysis, and the coverage of the research area is somewhat incomplete. To address it, this study analyzes the spatial distribution pattern of abandoned cultivated land in 2017 from the national scale by using land use change survey data and national geoinformation survey data (excluding Taiwan province, Hong Kong Special Administrative Region, and Macao Special Administrative Region). Also, we assess the impacts of abandoned cultivated land on grain yield. It is of great significance for filling the lack of quantitatively mapping abandoned cultivated land on a large scale and enriching current studies on cultivated land abandonment, thus providing the scientific basis and policy reference for the optimal utilization of cultivated land resources.