This series highlights the companies Carbon Drawdown Initiative has invested in.

Limestone has been used in farming for centuries.

What if it could also pull carbon from the air, for thousands of years to come?

That’s the breakthrough Silicate is working on: a practical, scalable way to sequester CO₂ by applying carbonate minerals to farmland. It’s enhanced weathering, but faster, cheaper, and already aligned with farming practices.

And the results are starting to speak for themselves.

The Origin: From soil pH to permanent carbon removal

Silicate was founded on a simple idea: carbonate minerals dissolve fast — orders of magnitude faster than silicates — and that speed can translate into meaningful, measurable carbon removal.

Their founder, Maurice Bryson, saw an opportunity to pair this chemistry with soil pH correction, which is a long-standing farming practice. Today, Silicate’s proprietary tools optimize where and how to apply limestone to maximize bicarbonate (HCO₃⁻) formation, the key mechanism for durable CDR.

The Work: Limestone, farms, and frontier science

Silicate relies more than most other enhanced weathering companies on directly measuring carbon removal in soil water, rather than inferring it. Their tools include:

Field selection models to identify optimal soils
Ion-tracked soil water lysimeters for HCO₃⁻ flux measurement
Isotope MRV to distinguish biogenic vs. geogenic CO₂

This isn’t lab-bound theory. Across Ireland and the US Midwest, Silicate has run 650+ hectare trials, removing over 6,000 tons of CO₂ at < $100 per ton.

Evidence: Real results from real soil

At Schott Farms in Illinois, Silicate is conducting one of the most detailed EW trials ever run in North America:

Trials compare sandy vs. clay soils to assess soil depth HCO₃⁻ transport
Long-term gas flux chambers track CO₂ and N₂O emissions
Biochar and variable-rate limestone amendments explore synergy effects

They’re tackling key questions for the field: How deep does carbon travel? When does calcite reprecipitate? Can N₂O offsets amplify the climate benefit?

This research — backed by XPRIZE, Shell GameChanger, and DOE Carbon Negative Shot — is already influencing how we think about MRV for EW.

The Vision: Global-scale CDR, rooted in local soil

The world has ~1.7 billion hectares of farmland suitable for this approach. At just 0.55 tCO₂ removed per hectare per year, that’s a theoretical pathway to >2 Gt CDR per year—using locally available minerals and existing equipment.

And because farmers already lime their fields, this isn’t an overhaul—it’s a smart upgrade.

Why we are backing them

We need drawdown solutions that are both credible and deployable. Silicate is delivering both.

They’re not just studying enhanced weathering. They’re rewriting its playbook—showing that better measurement, better chemistry, and farmer-first design can unlock real impact.

We’re proud to support them as they turn limestone into a climate asset—and give agriculture a new role in restoring the planet.

To learn more about their work, visit: https://www.silicatecarbon.com/

Portfolio Spotlight: Silicate - CDR with Calcite