Objective This study aimed to evaluate the remediation efficiency and carbon (C) sequestration benefits of peat addition in cadmium (Cd)-contaminated soil, in order to provide a theoretical framework for the ecological restoration of heavy metal-polluted croplands and the development of sustainable agriculture.

Method A pot experiment was conducted using Cd-contaminated paddy soil amended with varying dosages of peat (1%, 3%, 5%, and 8%, w/w). The effects on soil aggregate stability, total organic C, labile organic C, and bioavailable Cd were investigated. Furthermore, the Cd accumulation, biomass, and quality indicators of pakchoi (Brassica chinensis L. cv. Siji Huangguan) were determined.

Result Peat application significantly improved the aggregate structure of soil, especially in 8% peat treatment, the proportions of large macroaggregates (> 2 mm) and small macroaggregates (0.25 - 2 mm) were increased by 34.41% and 47.00%. While the proportion of microaggregates (< 0.25 mm) were decreased by 16.14% compared to the control. Meanwhile, the contents of soil organic C and readily oxidizable C were increased, synergistically reduced the contents of bioavailable Cd in soil and Cd accumulation in pakchoi. Especially, in 3% peat addition, the content of bioavailable Cd in soil was decreased by 7.69%, Cd accumulation in pakchoi was reduced by 34.30%, while the dry weight and soluble sugar content of pakchoi were increased by 57.64% and 8.80%.

Conclusion Peat application will not only improve soil aggregate structure, elevate soil C pool levels and enhance the potential of soil C sequestration and emission reduction, but also significantly immobilize soil Cd and promote crop growth. This study demonstrates that appropriate application of peat is an effective approach to achieving soil health management and agricultural green transformation, and holds significant importance for promoting the health and sustainable development of agricultural ecosystems.