Regionally Unbalanced Improvement of Cultivated Land Soil Quality in China since the 1980s

Cultivated land plays an important role in ensuring food security and achieving the Sustainable Development Goals (SDGs). However, the long-term spatiotemporal changes in cultivated land soil quality (CLSQ) at national scales are poorly quantified. Here, we provide the first comprehensive assessment of the spatiotemporal variations of CLSQ in China with 1 km resolution from the 1980s to 2010s, using a machine learning approach based on over 190,000 soil samples and environmental variables from all of China. The average CLSQ grade in China has significantly improved by 8.6 % (0.46 grades) over the past three decades. However, these changes are regionally unbalanced. Spatial patterns show that the Huang-Huai-Hai Plain experienced the biggest increase in high quality cultivated land since the 1980s, while in Northern and Western China there was an increase in low quality cultivated land from the 2000s, implying that these regions are facing cultivated land degradation. The unbalanced improvement of CLSQ in China reveals the impact of human activity on cultivated land soil quality and the importance of improving cultivated land soil quality in ecologically sensitive regions to ensure food and environmental sustainability.