Wollastonite addition stimulates soil organic carbon mineralization: Evidences from 12 land-use types in subtropical China

Enhanced rock weathering through adding silicate rock powder to soil has been increasingly considered as an effective means of removing CO2 from the atmosphere. However, the potential impact of silicate rock powder addition on the stability of soil organic carbon remains largely unknown, which adds an uncertainty to its effectiveness in mitigating atmospheric CO2. In this study, the response of soil CO2 efflux to wollastonite addition was evaluated for 12 land-use types in a subtropical region of China through an incubation experiment. Results showed that wollastonite addition significantly (P < 0.05) increased soil CO2 efflux over the control by an average of 330.97 +/- 29.25% during the incubation period. Approximately 90% of the variance in soil CO2 efflux was explained by soil properties in this study. Increased soil pH, dissolved organic carbon and available silicon induced by wollastonite addition were the main reasons responsible for the increase in soil CO2 emission. Soils having lower pH values responded to wollastonite addition with a higher increase in CO2 emissions. Based on numerous land-use types, our study showed that wollastonite application will cause substantial increase in the mineralization of soil organic carbon in acidic soil, which may weaken the effectiveness of enhanced rock weathering strategies as a tool for CO2 sequestration.

Automated summary

Enhancing rock weathering through the addition of silicate rock powder to soil has been proposed as an effective method to remove CO2 from the atmosphere. However, the impact of silicate rock powder on the stability of soil organic carbon and its effectiveness in mitigating CO2 emissions is not well understood. This study evaluated the response of soil CO2 efflux to wollastonite addition in different land-use types in a subtropical region of China. The results showed that wollastonite addition significantly increased soil CO2 efflux, with soil properties playing a major role in this response. The findings suggest that the application of wollastonite may lead to increased mineralization of soil organic carbon in acidic soil, potentially weakening the effectiveness of enhanced rock weathering as a CO2 sequestration tool.