<b>Wollastonite application showed negligible potential to enhance carbon sequestration in a subtropical fir plantation</b>

Enhanced rock weathering (ERW) involving the modification of soils with crushed silicate rocks<b> </b>has increasingly been considered for application to mitigate atmospheric CO₂. However, the potential of ERW as a CO₂ sequestration technology is still unclear, because silicate effect on ecosystem productivity was inadequately quantified before. In this study, ERW was deployed by adding 5 t ha^-1 of wollastonite rock powder to a young <i>Cunninghamia lanceolata</i> plantation. The C uptake by the ecosystem was estimated by integrating the inorganic C sequestration via rock weathering and the net ecosystem productivity (NEP). Results showed that 15.72 % of the cation (Ca²⁺ and Mg²⁺) delivered by weathering was charge-balanced by HCO₃^-, representing an CO₂ removal (CDR) of 0.32 t CO₂ ha^-1 year^-1 from ERW based on the charge-balance theory. The NEP, calculated as the difference between net primary production and cumulative heterotrophic respiration, averaged 162.91 and 137.38 g C m^-2 in control and wollastonite rock amended stands, respectively, with no significant difference observed between treatments. After integrating the CDR and NEP, we found that the C sequestration responded to WA with no change. We highlighted a minor<b> </b>potential for ERW to draw down atmospheric CO₂ in this forest.