Towards Coupled Organic–Inorganic Modeling of Carbon Cycling In Enhanced Rock Weathering Soils

Enhanced rock weathering (ERW) has emerged as a promising strategy to remove CO₂ from the atmosphere through the application of silicate rock dust to agricultural soils. To realize its full carbon sequestration potential, however, it is crucial to understand how mineral weathering interacts with soil organic carbon dynamics. Recent experimental work indicates that these interactions can substantially influence carbon cycling and cannot be neglected.

In this study, we couple the soil organic carbon model Millennial with the geochemical model PHREEQC, which is widely used in ERW research, to explicitly represent organic–inorganic interactions during weathering. We evaluate the integrated model against data from a mesocosm experiment and use this comparison to address three key questions: (i) which organic–inorganic interactions exert the strongest control on predicted carbon sequestration, (ii) which model components require further optimization to improve simulation accuracy, and (iii) which metrics are most informative for data-model integration in ERW experiments.

Our results highlight the importance of representing coupled organic and geochemical processes when quantifying carbon sequestration by enhanced weathering and provide guidance for both future model development and experimental design.