Enhanced Weathering on
Agricultural Land
THS v1.0 - Annex B
Enhanced Weathering on Agricultural Land applies crushed reactive silicate minerals - typically crushed basalt - directly to working cropland, integrating carbon removal into standard farming operations. As the mineral weathers, it converts atmospheric CO₂ to stable dissolved bicarbonate while also raising soil pH and supplying plant-available micronutrients, making this pathway distinctly hybrid: a technology-based mineral weathering mechanism operating within, and monitored alongside, a living agricultural system.
How this pathway works
Crushed basalt and other reactive silicate rock dusts, when spread across working cropland, undergo the same natural chemical weathering that has regulated Earth's atmospheric CO₂ over geological time - but at an accelerated rate, thanks to fine particle size and the elevated CO₂, organic acid, and moisture conditions of actively farmed soil. As the silicate minerals dissolve, they consume dissolved CO₂ and release calcium, magnesium, and bicarbonate ions, which are transported via soil water to groundwater and ultimately the ocean as stable, long-lived dissolved bicarbonate - while also neutralising soil acidity and releasing plant-available potassium, calcium, and micronutrients as an agronomic co-benefit.
Under the Teravent Hybrid Carbon Standard (THS v1.0) Annex B, this pathway is classified as hybrid rather than purely technological because crediting requires integrated monitoring of both the mineral weathering process (a technology-based mechanism) and the working agricultural system in which it operates - crop yield, soil health, and land management practices all interact with weathering rates and must be jointly assessed. Teravent Hybrid Credits (THC) are issued for verified net tonnes of CO₂ converted to stable dissolved bicarbonate, net of full lifecycle project emissions.
Three methodology variants are approved under Annex B, differentiated by cropping system - annual cropland, perennial orchard and vineyard systems, and integrated cover-crop applications that enhance weathering through root-zone chemistry.
THS v1.0 - Annex B
This pathway is governed exclusively by the Teravent Hybrid Carbon Standard (THS v1.0), the companion standard to TNS v1.0 (Nature) and TTS v1.0 (Technology) purpose-built for systems where biological and engineered carbon mechanisms are integrated and jointly monitored. No external registry, standard, or methodology is referenced or incorporated.
Three approved methodology variants
THS v1.0 Annex B approves three discrete methodology types, differentiated by cropping system. Each specifies its own application protocol, weathering rate assumptions, and agricultural monitoring requirements.
Finely crushed basalt is spread across annual cropland - maize, soy, wheat, and similar row-crop systems - typically during a routine field operation such as post-harvest tillage or pre-planting preparation, minimising additional farm labour. Repeated cultivation cycles help incorporate and expose fresh mineral surface area to soil moisture and CO₂, and the pathway benefits from established agricultural monitoring infrastructure already used for yield and soil health tracking on these farms.
- Basalt mass application rate per hectare, metered at ±5% accuracy
- Soil porewater alkalinity and cation concentration sampling at representative field locations, validated against a reactive transport weathering model
- Crop yield monitoring per growing season, both as an agronomic co-benefit indicator and a check on any unintended yield impact
- Soil pH and micronutrient status tracked to document the agronomic co-benefit alongside carbon removal
- Trace metal content assay of the basalt feedstock (nickel, chromium) confirming compliance with DNSH thresholds
Perennial cropping systems - orchards, vineyards, and tree crop plantations - offer a stable, undisturbed soil surface for silicate mineral application without the annual tillage disruption of row-crop systems, allowing continuous mineral-soil contact over multi-year timescales. This methodology requires longer-term soil monitoring given the extended crediting horizon typical of perennial systems, but benefits from reduced re-application frequency relative to annual cropland.
- Basalt mass application rate per hectare, metered at ±5% accuracy
- Soil porewater alkalinity and cation concentration sampling validated against a reactive transport weathering model, at extended multi-year intervals appropriate to perennial systems
- Fruit or perennial crop yield monitoring as an agronomic co-benefit indicator
- Soil pH and micronutrient status tracked over the extended crediting horizon
- Trace metal content assay of the basalt feedstock confirming compliance with DNSH thresholds
Cover crops planted between primary cash-crop cycles increase soil organic acid concentration and biological CO₂ production in the root zone, both of which accelerate silicate mineral dissolution relative to bare or fallow soil. This methodology explicitly integrates a cover cropping regime with silicate mineral application, crediting the combined weathering acceleration effect while also capturing any incidental soil organic carbon co-benefit from the cover crop itself (tracked separately under the applicable TNS soil carbon pathway where a project elects to register that component).
- Basalt mass application rate per hectare, metered at ±5% accuracy
- Cover crop species, planting, and termination schedule documented per field
- Soil porewater alkalinity and root-zone CO₂ concentration sampling, validated against a reactive transport weathering model calibrated for enhanced root-zone conditions
- Cash crop yield monitoring across the rotation to confirm no unintended yield impact from cover crop integration
- Trace metal content assay of the basalt feedstock confirming compliance with DNSH thresholds
Which emission sources must be counted
THS v1.0 Module 3 requires a dual-component accounting boundary spanning both the mineral weathering (technology) component and the agricultural system (biological) component, with a full lifecycle GHG emissions inventory deducted from gross weathering-derived CO₂ removal to arrive at the Net THC figure.
Measurement, reporting
& verification
Teravent's Science Advisory Board assesses each pathway against four MRV dimensions. Enhanced Weathering on Agricultural Land carries high measurement confidence on the mineral application side, but weathering rate confirmation in a complex, actively farmed soil system introduces more uncertainty than controlled industrial settings.
Basalt or silicate mineral application is metered at ±5% mass accuracy per hectare. Weathering-derived carbon removal is confirmed through soil porewater alkalinity and cation concentration sampling at representative field locations, calibrated against a site-specific reactive transport weathering model that accounts for soil moisture, temperature, and pH conditions unique to each farm. This model must be validated at each verification against fresh porewater samples. Crop yield and soil health indicators are tracked in parallel - both as required co-benefit documentation and as a cross-check that weathering application has not adversely affected agricultural productivity. All soil and porewater analyses must be conducted by an accredited laboratory.
Demonstrating additionality
THS v1.0 Module 2 requires a three-layer baseline: a biological baseline (the farm's standard crop production practice absent the weathering project), a technology baseline (common practice for deliberate mineral weathering application), and a combined system net baseline reconciling the two.
Leakage types & deductions
THS v1.0 Module 3 defines three leakage types applicable across all hybrid pathways. Enhanced Weathering on Agricultural Land is primarily subject to feedstock extraction leakage and a market-diversion consideration where the same land already receives conventional lime.
Buffer pool & NPRR assessment
All Annex B credits carry Class III Mineral permanence once dissolved bicarbonate transport is confirmed. Buffer pool rates are set through the THS Non-Permanence Risk Rating (NPRR) framework, which for this pathway centres on weathering rate model confidence and feedstock trace metal risk rather than reversal risk in the conventional sense - once formed, dissolved bicarbonate does not readily revert.
| Methodology | NPRR Rating | Buffer Pool Rate | Primary Uncertainty Drivers |
|---|---|---|---|
| ERW-M01 Annual Cropland | Low | 2–8% | Tillage-cycle variability affecting mineral-soil contact; weathering model calibration |
| ERW-M02 Perennial Systems | Very Low | 2–7% | Long crediting horizon requires sustained monitoring commitment; lower re-application uncertainty |
| ERW-M03 Integrated Cover Crop | Low–Medium | 2–10% | Root-zone weathering acceleration less extensively studied than baseline conditions |
Key registration criteria
Projects must meet all of the following minimum requirements to qualify for registration under THS Annex B. Additional methodology-specific requirements are detailed in the Annex B methodology tables for each ERW-M code.
Sustainable Development
Goal alignment
All Teravent registered Enhanced Weathering on Agricultural Land projects must complete an SDG impact assessment at registration and at each verification period. Four SDGs are systematically tracked for this pathway, reflecting its dual climate and agricultural productivity dimensions. Projects may apply for any of the eight THS co-benefit quality labels where independently verified indicators are met.
Deployment scope: Global - wherever basalt or reactive silicate rock deposits are accessible near agricultural regions, with current deployment concentrated in the U.S. Midwest, Brazil, and parts of Southeast Asia and Sub-Saharan Africa with existing basalt quarrying infrastructure.
Ready to register your
agricultural ERW project?
Submit a Project Concept Note under THS v1.0 Annex B to begin your registration. Select the ERW-M code matching your cropping system, calibrate a site-specific weathering model against soil porewater sampling, and appoint an accredited VVB to validate your PDD and three-layer baseline analysis.