Objectives This study aims to investigate the spatial and temporal evolution of soil organic matter (SOM) content in cultivated land and its driving mechanisms, thereby providing a theoretical basis for the protection and improvement of cultivated land quality in Jiangsu Province.

Methods Using national soil testing and fertilizer application datasets from 2010 and 2020, geostatistical methods and GIS spatial analysis techniques were applied to analyze the spatial and temporal evolution of SOM content in cultivated land across Jiangsu Province and identify the main influencing factors.

Results 1) The provincial average SOM content increased from 19.83 g/kg in 2010 to 25.15 g/kg in 2020, representing a rise of 26.83%. 2) Spatially, the SOM content was higher in the Lixiahe and Taihu Lake agricultural regions, moderate in the Riverside and Ning-Zhen-Yang Hilly agricultural regions, and lower in the Xu-Huai and Coastal agricultural regions. 3) Over the past 10 years, the highest average annual SOM content increase was observed in the Lixiahe (0.59 g/kg), Riverside (0.48 g/kg) and Xu-Huai (0.47 g/kg) agricultural regions, followed by the Ning-Zhen-Yang Hilly (0.39 g/kg) and Coastal agricultural regions (0.33 g/kg). The Taihu Lake agricultural region showed the smallest average annual increase (0.28 g/kg). 4) Natural factors, such as parent material and soil texture, had a limited influence on SOM content over the past decade, whereas anthropogenic factors, including fertilizer application, straw returning to the field, and construction land expansion, exerted increasing impacts, causing SOM content declines in some local areas.

Conclusions From 2010 to 2020, SOM content in cultivated land across Jiangsu Province showed an overall upward trend, with the spatial pattern remaining largely unchanged: higher SOM content in the Lixiahe and Taihu Lake agricultural regions, moderate levels in the Riverside and Ning-Zhen-Yang Hilly agricultural regions, and lower levels in the Xu-Huai and Coastal agricultural regions. In terms of the magnitude of change, the Lixiahe Riverside and Xu-Huai agricultural regions experienced the greatest increases in SOM content, followed by the Ning-Zhen-Yang Hilly and Coastal agricultural regions, while the Taihu Lake agricultural region had the least increase. The SOM content in cultivated land across Jiangsu Province is primarily influenced by natural factors such as parent material and soil texture. However, after 2010, the impact of human disturbances became more pronounced. Fertilizer application and straw returning to the field were the main factors contributing to the increase in SOM content in cultivated land across Jiangsu Province, while construction land expansion, soil salinization, and monoculture practices were the main causes of the decline in SOM content in certain local areas.