Enhanced Rock Weathering (ERW) is a method for removing carbon dioxide (CO₂) from the atmosphere by speeding up natural chemical reactions between rocks and water. To better understand how ERW works in real-world settings, we conducted a field experiment in an irrigated pasture in California. We added crushed rock to one side of a hillside and left the other side untreated for comparison. We then collected soil and water samples during and after rain and irrigation to monitor chemical changes over time.

Using a range of tools, from simple soil chemistry to novel isotopes, we tracked how rock weathering affects water chemistry and carbon cycling. Our early results show that adding rock boosts dissolved carbon and key elements in the soil water, a sign that weathering is happening. We also found signals of active mineral changes and cation exchange in the treated plots, especially during irrigation.

This study provides one of the first detailed views of how ERW plays out across both soil and water in a working agricultural system. By linking what happens in the soil to what flows out of it, we can better measure ERW’s impact on carbon removal and improve how it’s monitored at larger scales.