Accelerating weathering, lessons from a century of soil rejuvenation

Abstract

Enhanced rock weathering (ERW) is now widely discussed as a carbon dioxide removal (CDR) strategy, but many of the issues it faces were already evident in early agronomic experiments on crushed silicate rocks. This article revisits the pioneering work of Octave d’Hotman de Villiers in Mauritius during the 1930s–1950s, where crushed basalt was applied at very high rates (20–450 t ha−1) to highly weathered tropical soils to rejuvenate sugarcane productivity. We examine the rationale, experimental design, yield responses, and material constraints of these trials and situate them within the longer history of rock-dust fertilisation and modern ERW. The Mauritius experiments demonstrate that crushed basalt can produce agronomic benefits under specific soil, climate, and management conditions, while also showing constraints that remain central today: high material requirements, variable responses, and uncertain scalability. Reintroducing this history into contemporary debates shows that many central questions have persisted across successive waves of interest in silicate weathering. ERW should therefore be evaluated as a context-dependent intervention, not a universal climate solution, requiring site-specific evidence, rigorous measurement, and cautious interpretation of both agronomic and carbon outcomes.