Spatial-temporal patterns of complemented cropland and potential impacts on grain yield in China: from the...

Cropland abandonment reduces grain output, undermines national grain self-sufficiency, and threatens national and regional food security. Using sliding-window change detection and yield-assessment methods, this study extracts information on complement cropland in China over the past 30 years, identifies abandonment on complement cropland, and combines potential crop yield data to quantify the impacts of complement cropland and its abandonment on grain production. The results show that China has added 47.82 × 10⁴ km² of complement cropland relative to its 1990 cropland area; this complement cropland has mainly expanded along the periphery of traditional agricultural regions and is concentrated in the Southwest Region (SWQ), the Inner Mongolia and Great Wall Corridor Region (IMQ), and the Loess Plateau Region (LPQ), with its centroid shifting from the southeast toward the northwest. The cumulative abandoned area of complement cropland accounts for 20.18% of the total complement cropland area, with abandonment showing strong spatial clustering in IMQ and SWQ; the average annual abandonment rates in these two regions are 24.08% and 19.50%, and 18.9% and 16.0% of the complement cropland parcels have experienced abandonment at least once, both clearly higher than in other regions. Complement cropland has an average potential grain output of about 67.58 × 10⁸ kg per year, yet abandonment causes an annual loss of approximately 5.21 × 10⁸ kg in production capacity. Yield losses from abandonment are close to 10% of the potential output from complement cropland; among the regions, the Middle and Lower Yangtze River Region (YRQ) has the highest annual loss share at 20.8%, followed by SWQ and IMQ at 17.6% and 15.8%, respectively. Overall, cropland abandonment reduces grain supply and amplifies national food security risks, and its erosive effect on production capacity warrants close attention. HIGHLIGHTS: • Slide the window to identify abandoned complement cropland. • Nearly half of China's complement cropland area was abandoned in IMQ and SWQ between 1990 and 2023. • Over the past 30 years, the yield loss attributable to the abandonment of complement cropland has approached 10% of its potential output.