Increased grain production of cultivated land by closing the existing cropping intensity gap in Southern China

To achieve food security, closing the cropping intensity gap (CIG) between realizable and actual cropping systems is the most effective way to increase grain production (GP) with lower environmental costs. Numerous studies have explored the yield gap between the potential and actual crop yields, but few studies have analysed the changes in GP by closing the CIG. The GP gap, a difference between attainable and actual GP, was estimated by closing the CIG at the cropping system level in 775 counties of Southern China. Results showed that the GP gap by closing the CIG was 84.27 Mt, accounting for 69% of the total actual GP, which was mainly distributed in the Yanjiang plain Subzone, Pengdong hills and mountains Subzone, Huanan low plain Subznone, and Jiangnan Zone. The total attainable GP was estimated to be 206.63 Mt as the CIG was closed. Furthermore, when all the cultivated land was used to grow grain crops, the attainable GP reached 367.83 Mt, indicating that the study area could supply 64% of the national actual GP with 25% of the national cultivated land. These findings indicate that closing the CIG of cultivated land in this region will be feasible to increase GP to ensure the national food security and promote sustainable agriculture as a main source of national food production with less ecological pressure.