First name: Auston
Last name: Collings
Class Year: 2026
Advisor: Noah Planavsky
Essay Abstract:
Limiting global warming to well below 2°C requires not only rapid decarbonization but also active carbon dioxide removal (CDR). Enhanced rock weathering (ERW), which accelerates natural silicate dissolution by applying finely ground rock to agricultural soils, has emerged as a promising removal strategy with co-benefits for soil fertility. This thesis evaluates field-scale evidence for basalt weathering and associated carbon dioxide removal at an actively managed no-till farm in Clarksville, Virginia. Basalt was applied at 20 U.S. tons per acre across 23 treatment plots in June 2024, with 25 unamended control plots as references. Total soil carbon (TC) and pH were tracked across four sampling events spanning fourteen months, while calcium, magnesium, sodium, chromium, and base saturation were measured through April 2025. Bulk soil carbon did not differ between groups at any sampling event, consistent with ERW-derived carbon being exported as dissolved bicarbonate rather than accumulating in solid-phase pools. Soil pH, total cation concentrations, chromium, and base saturation all increased significantly in basalt-amended plots relative to controls, providing convergent geochemical evidence of silicate dissolution. Applying a chromium-normalized mass-balance framework, carbon dioxide removal was estimated at approximately 4.25–4.27 tCO2ha-1 across the first ten months of deployment under a soil mass-balance approach, with a feedstock-scaling approach yielding a higher but directionally consistent estimate of 6.55–6.74 t CO2ha-1.