Abstract: ObjectiveAgainst the background of carbon neutrality, the enhanced carbonate weathering carbon sink serves as a viable tradable carbon sink pathway. It accelerates carbonate rock dissolution and sequesters atmospheric CO₂ through large-scale application of carbonate rock powder. The input of carbonate mineral powder can theoretically change soil pH and charge properties, which may further affect the interaction between exchangeable cations and dissolved organic carbon (DOC). However, this critical process still lacks sufficient empirical research verification. MethodsA soil incubation experiment with calcium carbonate addition was conducted using typical karst soil (brown calcareous soil) and non-karst soil (zonal red soil) as test materials, to investigate the variations in exchangeable cations, dissolved organic carbon content and soil carbon dioxide release between calcareous soil and red soil. ResultsThe soil pH of both calcareous soil and red soil increased significantly after calcium carbonate addition. Exchangeable cations in calcareous soil were dominated by exchangeable calcium (E-Ca), and the relative proportion of E-Ca increased slightly following calcium carbonate application. By comparison, exchangeable cations in red soil were mainly dominated by exchangeable aluminum (E-Al). After calcium carbonate addition, E-Ca content rose substantially, while E-Al content decreased markedly. Both DOC content and soil CO₂ emissions in the two soil types increased significantly(p ＜ 0.01). ConclusionsExogenous calcium carbonate input alters the composition and concentrations of soil exchangeable cations, thereby regulating soil DOC content and driving a synchronous increase in soil CO₂ emissions in the short term. In the long run, the relevant carbon may participate in the inorganic carbon cycle without obvious CO₂ release. The findings of this study provide a scientific basis for the formulation of enhanced carbonate weathering strategies, and are of great significance for realizing the national strategic goals of carbon peaking and carbon neutrality.