Spatiotemporal Variation of Soil Organic Carbon and Assessment of Carbon Sequestration Potential in Xinmi City of Henan Province

Objective This study aims to investigate the spatiotemporal variation characteristics of surface soil organic carbon (SOC) in a typical agricultural area of central Henan Province (with Xinmi City as the study area), evaluate its carbon sequestration potential, propose recommendations for enhancing carbon sequestration and sink capacity, and provide a scientific basis for improving regional soil carbon sink function and promoting sustainable agricultural development.Methods Based on multi-period measured data of surface soil (0–20 cm) in Xinmi City, soil carbon density and its changes were calculated. The ordinary kriging interpolation method was used to generate spatial distribution maps of soil carbon density and its variations. The soil organic carbon saturation value method was applied to assess soil carbon storage capacity and carbon sequestration potential.Results High-value areas of SOC density in the study area are influenced by Huangchao soil and fluvo-aquic cinnamon soil. The SOC density ranges from 0.57 to 17.22 kg/m², with the average value varying from 3.90 to 13.15 kg/m², showing significant differences among different soil types. Due to farmland management practices and urban development, SOC density changed at different stages: from 1985 to 2006, the surface SOC density varied from -9.03 to 4.01 kg/m², showing a decreasing trend; from 2006 to 2025, the surface SOC density varied from -4.89 to 14.39 kg/m², with a significant increase. Additionally, SOC content decreased significantly with the increase of soil depth. Among different soil types, carbonate cinnamon soil and cinnamon soil had the largest total carbon sequestration potential due to their large distribution areas, while Huangchao soil had the smallest total carbon sequestration potential. The total soil carbon sequestration potential of the study area was approximately 22.97 Tg.Conclusion The surface SOC density in the typical agricultural area of central Henan Province exhibits significant temporal variations across different periods. The overall carbon sequestration capacity is strong, but there are differences among different soil types. To enhance the carbon sequestration effect, priority should be given to optimizing the land use structure and improving the scientific nature of agricultural management measures. This conclusion can provide a reference for improving soil carbon sink function in similar areas of central China.