Evaluating Cropland Quality and Improvement Potentials in the Middle-lower Yangtze River Plain, China

Cropland quality (CQ) is crucial for understanding spatial patterns and sustainable land use. Traditional CQ evaluation methods, such as grid and random point sampling, required high-density & site-specific measurements, which made them prohibitively time-consuming and labor-intensive for large-scale surveys. Therefore, this study introduced a nature-society-ecology index system to evaluate large-scale CQ in the Middle-lower Yangtze River (MLYR) plain, China by integrating satellite-derived data, statistical data, and the improved TOPSIS model. The coupling coordination degree (CCD) and obstacle degree models were then applied to diagnose CQ challenges and identify improvement strategies. Results showed that: 1) CQ generally presented high values in coastal plains but low values in mountain areas. The CQ values fell within the range of 0.5–0.6. 2) The spatial patterns of the subsystem CCD revealed that 73% of MLYR plain was in the barely uncoordinated stage, while 25% was borderline uncoordinated. Highly coordinated regions were primarily concentrated in low plain areas. 3) The primary constraints on CQ in the MLYR plain stem from poor soil texture and insufficient agricultural modernization. Low multiple cropping levels, combined with imbalanced agricultural carbon emissions and limited carbon absorption capacity, emerged as the key weak attributes. These findings suggest that targeted soil improvement and increased investment in agricultural mechanization could synergistically enhance both CQ and productivity.