Objective This study aims to explore the spatio-temporal characteristics of soil organic carbon (SOC) content and its change rate (SOC_r) in cultivated land in Shenyang City over the past 40 years, thereby to provide basic data for cultivated land protection and the realization of the dual carbon goals.

Method By means of the methods of Inverse Distance Weight interpolation and GIS spatial analysis, combining with the data from the soil survey in 1980, 2008 and 2020 in Shenyang City, the spatio-temporal characteristics of SOC content and SOC_r of cultivated land during these periods were analyzed.

Result SOC content and SOC_r of cultivated land in Shenyang showed a trend of decreasing first (1980–2008) and then increasing (2008–2020) in recent 40 years. The average SOC content of cultivated land in Shenyang in 1980, 2008 and 2020 was 10.58, 10.09 and 11.27 g kg⁻¹, respectively. Among them, it in 2020 was the highest, with an increase of 6.52% compared with 1980 and an increase of 11.10% compared with 2008. The SOC_r of cultivated land in Shenyang in the early period (1980–2008), the later period (1980–2008) and the overall past 40 years (1980–2008) was -0.02, 0.10 and 0.02 g kg⁻¹ a⁻¹, respectively. From the perspective of the district and county scale, the SOC_r of cultivated land in Yuhong District, Xinmin City and Kangping County in each period was positive, and the overall SOC_r was significantly increased compared with the previous period (P < 0.05), indicating that the soil carbon sequestration capacity was further enhanced. The SOC_r in Sujiatun District, Shenbei New District and Liaozhong District over the past 40 years was reversed from a negative value to a positive value, indicating that the decline trend of SOC in the previous period was reversed and the transformation from "carbon source" to "carbon sink". Although the SOC_r in Faku County over the last 40 years was still negative, after improvement and fertilization, it had significantly increased compared with the previous periods (P < 0.05). Only SOC_r in Hunnan District was further decreased.

Conclusion SOC content and SOC_r of cultivated land in Shenyang were significantly increased (P < 0.05), and the cultivated land soil had transformed from a "carbon source" to a "carbon sink", indicating that the input of SOC improvement and cultivated land quality cultivation projects had achieved remarkable results in recent years. In the future, the policies for the protection and improvement of cultivated land SOC should be formulated based on the spatio-temporal characteristics of cultivated land SOC_r in each region and local conditions.