Direct measurement of carbon dioxide removal due to enhanced weathering

Enhanced weathering (EW) is a durable carbon removal strategy with clear pathways to produce significant global supply on a decadal scale. Despite increasing interest and investment in this process, there have been limited direct, continuous observations of weathering rates. In this study, we monitor a basalt-applied soybean plot in Southeast Virginia using continuous in-soil CO2 monitors. We provide clear evidence of CO2 flux reduction within the soil profile, equating to 1.04 t/ha/yr. This removal is most substantial in the active growing season and following significant rain pulses. This work supports that direct and continuous gas-phase measurements will play an important role in advancing our understanding of the timescale of enhanced weathering rates, and demonstrating enhanced weathering to be a rigorous, scalable method of durable carbon removal.