Enhanced weathering leads to substantial C accrual on crop macrocosms

Abstract. Enhanced weathering (EW) is proposed as a key strategy for climate change mitigation. It involves the application of silicate rock powder to soils, where it is expected to react with CO₂ released from soil respiration, forming stable carbonate ions and thereby sequestering carbon. Here, we evaluated the effects of EW on a crop ecosystem within a macro-scale ecotron – an enclosed facility enabling complete quantification of carbon fluxes among the atmosphere, vegetation, soil, and leachates. EW treatment resulted in an almost three-fold enhancement of measured carbon flux into the soil, achieving rates up to 1.5 tons per hectare. Furthermore, the magnitude of carbon sequestration exceeded what could solely be attributed to electrochemical transformations. Therefore, we conclude that EW facilitated significant carbon accrual in our simulated ecosystems via not only carbonate precipitation but also enhanced biogeochemical activities promoting additional carbon storage. Based on these findings, we speculate on the underlying pathways responsible for such outcomes.