Objectives Soil organic carbon content can directly reflect soil fertility levels, and its storage plays a crucial role in the global carbon balance. Yingxian County is located in the ecologically fragile area of the North Loess Plateau. Studying the spatial and temporal distribution and influencing factors of soil organic carbon storage in cultivated land in this county can provide a theoretical basis for improving soil fertility and protecting the agro-ecological environment in the Loess Plateau region.

Methods Based on soil properties (soil organic carbon, soil nutrients, etc.) of cultivated land in Yingxian County, Shanxi Province, in the years 1983, 2010, and 2023, and relevant agricultural production data (crop yield, planting area, livestock and poultry breeding, etc.) spanning from 1983 to 2023, classical statistics, geostatistics, variance decomposition, and the random forest model were used to quantify the spatial and temporal distribution patterns and main influencing factors of soil organic carbon storage in the surface soil layer (0−20 cm).

Results Soil organic carbon content and soil organic carbon storage in the surface layer (0−20 cm) of cultivated land in Yingxian County showed an increasing trend from 1983 to 2023, with a net increment of 3.20 g/kg and 8.30 t/hm², respectively. From a spatial perspective, soil organic carbon content and soil organic carbon storage were higher in southern Yingxian County. From 1983 to 2010, Nanquan Township, located in the southern region of Yingxian County, experienced the greatest increase in soil organic carbon storage, with an increment of 10.14 t/hm². From 2010 to 2023, Xiamayu Township, located in the southwest of Yingxian County, had the largest increase in soil organic carbon storage (10.79 t/hm²). In the past 40 years, the carbon input of Yingxian County showed an increasing trend, with an average annual carbon input of 2.15 t/(hm²·a), and the soil carbon sequestration rate and carbon sequestration efficiency in the topsoil layer were 0.21 t/(hm²·a) and 9.67%, respectively. In addition, the soil carbon sequestration rate and carbon sequestration efficiency in the earlier period (1983−2010) were lower than those in the later period (2010−2023). Spatially, the carbon sequestration efficiency of each township in Yingxian County has varied over the past 40 years. The carbon sequestration efficiency in Baimashi Township and Xiamayu Township was higher (19.07%, 17.34%), while Zhenziliang Township had the lowest carbon sequestration efficiency (2.83%). Currently, carbon input and soil properties (bulk density, total nitrogen, and available potassium content) are the main factors affecting soil organic carbon storage in Yingxian County.

Conclusions Over the past 40 years, the increase of carbon input significantly increased the cultivated land soil organic carbon storage in Yingxian County, and the change trends among the different townships were quite different. It is suggested that more organic fertilizer should be applied in the north-central region of Yingxian County, such as in Dalinhe Township and Zangzhai Township, where soil organic carbon storage is low, to improve soil fertility and increase soil carbon sequestration.