Enhanced rock weathering (ERW) is a proposed method of carbon dioxide sequestration that involves spreading crushed silicate minerals on soils to drive chemical reactions that form carbonate minerals: Essentially, the idea is to boost the natural process of rock weathering, in which carbon is transferred from the atmosphere into rocks. But few large-scale field studies of ERW exist, making it difficult to determine the technique’s practical feasibility and what factors might limit or enhance its success.