# Mapping Abandoned Cultivated Land in China: Implications for Grain Yield Improvement
## 3 Results
### Assessing the Impacts of Cultivated Land Abandonment on Grain Yield  
In 2017, the total grain yield loss due to cultivated land abandonment reached 40.89 million tons in China, accounting for 6.48% of the total grain yield, and the grain yield loss caused by cultivated land abandonment reached 254.45 million tons. In terms of provincial differences, cultivated land abandonment in Heilongjiang and Shandong provinces had the greatest impacts on grain yield. The loss of total grain yield in these two provinces was 0.6593 million tons and 0.5630 million tons, making up 9.22% and 7.87%, respectively. The Inner Mongolia Autonomous Region, Jiangxi, and Yunnan provinces followed, with grain yield loss of more than 0.4 million tons each. Obviously, as the market economy continued to progress, there was a remarkable transformation from grain crop planting to cash crop planting. Simultaneously, as a result of the gap between agricultural and non-agricultural incomes, a large number of young laborers were employed in urban areas, thereby causing cultivated land abandonment. Cultivated land abandonment was widespread in the region, leading to a significant decline in the regional grain planting area, and the impact of cultivated land abandonment on total grain yield was relatively large. However, Hainan, Beijing, Shanghai, and Tianjin lost less than 0.1 million tons of grain yield. Spatially, the impact of cultivated land abandonment on grain yield showed a spatial distribution pattern, with a higher value in the eastern region and a relatively lower value in the western region. The regions generating significant impact on grain yield due to cultivated land abandonment were mainly concentrated in Northeast China, the North China Plain, the middle and lower reaches of the Yangtze River, the Sichuan Basin, and other regions, forming a relatively significant cluster region. It can be seen that the grain yield in traditional major grain-producing regions was more affected by cultivated land abandonment. In Jiamusi City, Harbin City, Chongqing City, and Wenshan Zhuang Autonomous Prefecture, grain yield loss due to cultivated land abandonment was generally high, all of which exceeded 0.1 million tons. But in the southeast coastal area and western area, grain yield loss quantity was generally low, together with each county-level unit grain yield loss of less than 0.1 thousand tons (Table 3). Further, according to the differences in grain yield across three grain production functional regions, the cultivated land abandonment generated different implications for grain yield in the major grain-producing regions, major grain-marketing regions, and producing-marketing balance regions. Specifically, the major grain-producing regions were the most affected by the cultivated land abandonment, with a loss of 4.8475 million tons of grain yield, accounting for more than 65% of the total loss of grain yield. The major grain-producing regions faced significant challenges in ensuring the national food supply by maintaining high grain yield levels. The region experiences a significant reduction in grain yield due to the frequent abandonment of cultivated land, largely driven by the substantial consumption of cultivated land resources and the increasing vulnerability of such lands. The major grain-marketing regions showed less impact on grain yield caused by cultivated land abandonment, with a loss of only 0.1441 million tons. This is mainly because with the acceleration of urbanization, the dependence of farmers on cultivated land in the major grain-marketing regions was weakened, and there existed a large number of agricultural laborers immigrating from the countryside to the city, which led to regional abandonment of cultivated land and a continuous decline in the area under effective grain cultivation.