Farmland that pulls CO2 out of the air with crushed rock

How far are we from enhanced rock weathering removing millions of tonnes of CO2 a year on farmland?

Crushed silicate rock spread on fields can lock CO2 into carbonate over time, and a few field trials have been published. Registries have issued small volumes so far: 235.53 credits from one project in Brazil in January 2025, and a larger claim in December 2025 that CarbonPlan disputes. The removal in trials is mostly calculated from soil and porewater chemistry, not measured directly, and a published national-scale model for US farmland gives 0.16 to 0.30 Gt CO2 a year by 2050, limited by how fast basalt can be supplied.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREPilots

Close. Early pilots are running in the real world.

Field trials have measured soil and porewater changes on real farmland, and registries have issued credits under verification protocols. Removal figures come from calculations based on soil and porewater chemistry, and the trials are few, short or unreplicated. No sources reviewed show verified removal at national scale, so the stage is pilot rather than scaling.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: Farmland that pulls CO2 out of the air with crushed rock Unlocked Being researched Locked
  1. 2018Enhanced rock weatheringPilot and early commercial Unlocked.
  1. 2024Four-year field trial on US croplandDone Unlocked.
  2. 2025First registry-issued enhanced weathering creditsDone Unlocked.
  3. 2025Porewater trial on Scottish pastureDone Unlocked.
  4. 2026Measured versus calculated removal disputed for a large issuanceIn progress Being researched.
  5. 2026Offtake contracts with delivery dates into 2029In progress Being researched.
  6. Date not recordedVerified removal at national scale on US farmlandNot started Locked.
  7. Date not recordedRock supply at the scale neededNot started Locked.
  1. GoalFarmland that pulls CO2 out of the air with crushed rockGoalRequires: Enhanced rock weathering, Four-year field trial on US cropland, Porewater trial on Scottish pasture, First registry-issued enhanced weathering credits, Measured versus calculated removal disputed for a large issuance, Offtake contracts with delivery dates into 2029, Verified removal at national scale on US farmland, Rock supply at the scale needed. Locked.

The road so far

3 of 7 steps done, 2 in progress.

  1. Done · 22 Feb 2024Four-year field trial on US cropland

    Beerling and colleagues reported a four-year trial in the US Corn Belt, with basalt applied each autumn at 50 tonnes per hectare. The paper gives a conservative cumulative CDR potential of 10.5 ± 3.8 t CO2 per hectare, and maize and soybean yields rose by 12 to 16%. The removal figure comes from soil cation accounting, not from direct measurement of removed carbon. [1]

  2. Done · 5 Sept 2025Porewater trial on Scottish pasture

    McBride and colleagues measured porewater on pasture near Stirling for about 1.5 years, at 78 and 126 tonnes of basalt per hectare. They estimate direct removal of 0.33 to 0.53 t CO2 per hectare at 5 cm depth, and 0.257 to 0.413 t after a 22% deduction for outgassing and losses. The trial had one plot per treatment, and the rates are above normal spreading practice. [3]

  3. Done · 6 Jan 2025First registry-issued enhanced weathering credits

    Isometric reports 235.53 credits from InPlanet's Serra da Mantiqueira project in Brazil, certified ex post from soil and porewater measurements against control plots. The credits were delivered to Adyen through ClimeFi. The source is the registry's own announcement, and its claims have not been checked independently. [4]

  4. In progress · 20 Apr 2026Measured versus calculated removal disputed for a large issuance

    CarbonPlan says a Lithos facility received 2,362 Puro certificates in December 2025 and that its claimed gross flux of 8.3 t CO2 per hectare per year is about three times the rate in Beerling and colleagues' 2024 trial. CarbonPlan says the claim cannot be replicated from public documentation because the monitoring data and modelling assumptions have not been disclosed. CarbonPlan reports no response from Lithos or Puro. [5]

  5. In progress · 11 Jun 2026Offtake contracts with delivery dates into 2029

    CDR.fyi reports a three-year offtake agreement between Microsoft and Alt Carbon for 36,920 tonnes of enhanced weathering credits, with delivery by 2029. The same page reports about 72,000 tonnes sold to date by Alt Carbon. It does not report how much of that has been delivered, so sales and delivered removal are different figures. [6]

  6. Not startedVerified removal at national scale on US farmland

    Beerling and colleagues estimate 0.16 to 0.30 Gt CO2 a year from US cropland by 2050, and 0.25 to 0.49 Gt by 2070. These are model estimates that assume basalt is available at the rates the scenarios need. No national programme has measured removal at this level, and the sources reviewed do not show it.

  7. Not startedRock supply at the scale needed

    The Nature study says the pathway is constrained by the rate at which basalt can be supplied. Its scenarios assume 1 to 2 Gt of rock a year by 2070. Current supply chains are not shown to reach that scale in the sources reviewed.

Why it matters

Farmland already has tilled soil, fertiliser and spreading equipment, so spreading rock could in principle remove CO2 at a large scale without new land. Whether it does depends on how removal is measured and credited. If the measurement is weak, credits could be issued for more removal than the soil actually holds, and buyers would pay for it. Tracking the gap between measured and modelled removal shows whether the method can be trusted at the scale claimed.

What stands in the way

  • Measurement: removal in the trials is calculated from porewater or soil chemistry, and the Scottish trial had no replication. Direct measurement of removed carbon at field scale is not shown in the sources reviewed.
  • Disputed credits: CarbonPlan argues that the claimed flux for one large Lithos issuance is above about 90% of rates across published experiments, and that the monitoring data needed to check it have not been published.
  • Rock supply: the Nature study says the pathway is limited by how fast basalt can be supplied, and its scenarios need 1 to 2 Gt of rock a year by 2070.
  • Energy and emissions from grinding: a 2022 life-cycle study across twelve nations found that grinding rock, not mining it, has the largest effect on environmental impacts. Transport emissions depend on distance, and the sources reviewed do not quantify this for farm deployment.
  • Farmer uptake: the sources reviewed do not report evidence on farmer adoption, cost to farmers, or how payments for credits reach them.

Published forecasts

What others have predicted. These are their estimates, not ours.

WhoForecastTimeframeMade
Beerling and colleagues, Nature (2025), model estimateEnhanced weathering on US cropland could remove 0.16 to 0.30 Gt CO2 a year by 2050, constrained by how fast basalt can be supplied. This is a model estimate, not a measured outcome. [2]20505 Feb 2025

Signals to watch

  • Lithos or Puro publishing the monitoring data and modelling assumptions behind the 2025 issuance, or correcting it.
  • An independent field trial with replicated plots that measures carbonate or cation export at more than one site.
  • Delivered tonnes from Alt Carbon and other suppliers published alongside sold tonnes, so the gap between the two is visible.
  • A peer-reviewed study of transport and grinding emissions for a stated farm distance, with the energy mix used.
  • Published data on farmer uptake, including how many hectares are treated and what farmers are paid.

Sources

  1. peer reviewed paper
    Enhanced weathering in the US Corn Belt delivers carbon removal with agronomic benefits
    David J. Beerling, Dimitar Z. Epihov, Ilsa B. Kantola et al.. Proceedings of the National Academy of Sciences, 22 Feb 2024.
  2. peer reviewed paper
    Transforming US agriculture for carbon removal with enhanced weathering
    David J. Beerling. Nature, 5 Feb 2025.
  3. peer reviewed paper
    Quantifying potential carbon dioxide removal via enhanced weathering using porewater from a field trial in Scotland
    Amy L. McBride, Kirstine Skov, Peter Wade. Frontiers in Climate, 5 Sept 2025.
  4. company announcement
    World's first independently verified Enhanced Weathering credits
    Isometric, 6 Jan 2025.
  5. news
    Questions about Lithos' first ERW credit issuance
    Tyler Kukla, Freya Chay, Kate Maher. CarbonPlan, 20 Apr 2026.
  6. news
    CDR deal alert, 11 June 2026
    CDR.fyi, 11 Jun 2026.
  7. peer reviewed paper
    Environmental and health impacts of atmospheric CO2 removal by enhanced rock weathering depend on nations' energy mix
    Rafael M. Eufrasio, Euripides P. Kantzas, Neil R. Edwards et al.. Communications Earth & Environment, 2022.

Last reviewed 21 Oct 2026.