Overview
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.
📌
Class III — Mineral permanence. All credits issued under THS Annex B carry Class III permanence, reflecting the >1,000-year stability of dissolved bicarbonate once transported to groundwater or ocean storage. Buffer pool contributions of 2–10% of gross verified credits apply, among the lowest in the Teravent Hybrid system, though somewhat higher than standalone TTS mineral pathways given the added complexity of monitoring weathering rates within an actively managed farm system.
Governing Standard
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.
TCR›
THS v1.0›
Annex B — Enhanced Weathering on Ag. Land›
ERW-M01 through ERW-M03
M02
Three-layer baseline: biological (crop system) baseline, technology (weathering) baseline, combined net system baseline
M03
Dual-component accounting boundary, Net THC formula, eight carbon pool assessment table, dMRV and remote sensing protocols
M04
Class III mineral durability · Buffer pool 2–10% · NPRR assessment framework
M05
Do No Significant Harm across soil health, biodiversity, water resources, and food security; trace metal limits on feedstock
M06
Ten-stage registration; 17-element PDD; Standard, Premium, Frontier certification tiers
M07
THC serial: TCR–THS–ERW–[Country]–[ProjectID]–[Vintage]–[DurabilityClass]–[Unit]
Teravent Hybrid Credit — Serial Number Format (THS Annex B · Class III)
TCR
–
THS
–
ERW
–
BR
–
00047
–
2025
–
III
–
000001
💡
Hybrid credits carry a single credit type: Unlike TTS credits, THC serials do not distinguish Removal from Reduction — every THS pathway represents a durable carbon removal outcome achieved through an integrated biological-technological system. The durability class is embedded directly in the serial number instead, since a single hybrid project can generate credits across multiple durability classes simultaneously (for example, a Class I biological soil carbon fraction alongside a Class III mineral weathering fraction).
Methodologies Accepted
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.
Durability
Class III · Mineral
Buffer Pool
2–8% (by NPRR)
Application Metering
Basalt mass applied per hectare, ±5%
Weathering Confirmation
Soil porewater alkalinity sampling, reactive transport modelling
Co-Benefit Monitoring
Crop yield and soil pH tracked alongside carbon removal
Weathering Timeline
Multi-year, climate and particle-size dependent
Key Monitoring Indicators
- 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.
Durability
Class III · Mineral
Buffer Pool
2–7% (by NPRR)
Application Metering
Basalt mass applied per hectare, ±5%
Re-Application Frequency
Lower than annual cropland given undisturbed surface
Co-Benefit Monitoring
Fruit/crop yield and soil health tracked long-term
Weathering Timeline
Multi-year to decadal
Key Monitoring Indicators
- 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).
Durability
Class III · Mineral (weathering fraction)
Buffer Pool
2–10% (by NPRR)
Application Metering
Basalt mass applied per hectare, ±5%
Cover Crop Requirement
Documented species and planting schedule required
Cross-Pathway Note
Soil organic carbon fraction credited separately if elected
Weathering Timeline
Accelerated relative to ERW-M01, root-zone dependent
Key Monitoring Indicators
- 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
Dual-Component Project Boundary & GHG Accounting
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.
Required
Mineral Weathering CO₂ Removal (Gross)
Primary benefit quantity. Modelled CO₂ conversion to dissolved bicarbonate, validated against soil porewater alkalinity sampling and a site-calibrated reactive transport weathering model.
Required
Feedstock Mining, Crushing & Transport
Emissions from basalt or other silicate mineral mining, crushing to the required particle size, and transport to the farm, following THS Module 3 lifecycle assessment requirements.
Required
Application Equipment Energy
Fuel or electricity consumed by spreading equipment during mineral application, integrated where possible with existing farm equipment operations to minimise additional energy use.
Tracked separately
Soil Organic Carbon (Biological Component)
Where a project also demonstrates soil organic carbon gains (e.g. from cover cropping under ERW-M03), this biological fraction is assessed and credited separately as Class I, disaggregated from the Class III mineral fraction in the issuance record.
Excluded
Baseline Farm Operations
Emissions from the underlying farm's standard crop production operations (irrigation, fertiliser application, harvest) that would occur regardless of the weathering project are excluded from this pathway's boundary.
MRV Confidence
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.
Application QuantificationVery High
Weathering Rate ConfirmationMedium–High
Permanence ConfidenceHigh
Additionality ClarityHigh
🔬 Measurement Requirements — THS Module 3
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.
Additionality
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.
1
Common Practice Test
Deliberate silicate mineral application for carbon removal purposes remains uncommon in most agricultural regions, distinct from unrelated agricultural lime application for soil pH management (which uses different feedstock and application rates). Projects must document that basalt application at the rate and specification required for carbon removal exceeds any regional common practice of incidental soil amendment.
2
Regulatory Surplus Test
The mineral application activity must not be mandated by any legally binding soil amendment, land management, or agricultural regulation. Where a jurisdiction requires standard agricultural lime application for unrelated pH management purposes, projects must demonstrate the specific silicate weathering programme goes beyond that requirement.
3
Financial Additionality Test
Carbon revenue must be necessary for project viability. Developers must submit a discounted cash flow analysis, net of any government agricultural grants or soil health incentive programmes (disclosed under Module 8) and net of any agronomic yield or fertiliser-offset benefit, demonstrating that feedstock, application, and monitoring costs exceed available revenue absent carbon credit income.
ℹ️
Government incentive disclosure: Where a project receives direct government agricultural grants, soil health incentive payments, or per-tonne carbon removal tax credits, this must be disclosed to the TSA at registration under Module 8. Double-claiming the same carbon benefit under both a government incentive programme and Teravent credits is prohibited.
Leakage Assessment
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.
Feedstock Extraction Leakage
Mining Emissions & Land Disturbance
Crushing and mining basalt feedstock carries embodied mining emissions and potential land disturbance at the quarry site, which must be included in the project's lifecycle inventory rather than treated as an external leakage source.
Included as required boundary item, not separately deducted
Conventional Lime Displacement
Reduced Agricultural Lime Purchases
Where basalt application displaces a farm's conventional agricultural lime purchases for pH management, the counterfactual lime production and transport emissions avoided must be documented, but not double-counted as an additional carbon credit beyond the weathering removal itself.
Documented as co-benefit context, not separately credited
Energy-Source Leakage
Application Equipment Fuel Use
Where spreading equipment requires dedicated trips beyond existing farm operations, associated fuel combustion emissions must be included in the lifecycle inventory using the applicable emissions factor.
Included as required boundary item per THS Module 3
Permanence & Weathering Rate Risk
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 |
⚠️
Biochar stability protocol note: Where a project combines silicate weathering with biochar application (see Agroforestry with Biochar, Annex C, or Biochar Production & Soil Application, Annex A), the biochar fraction is separately assessed under the THS Module 4 H/Corg atomic ratio stability protocol and credited at its own Class II durability, disaggregated from the Class III mineral weathering fraction. Reversal notification for the mineral fraction requires TSA notification within 72 hours of any confirmed weathering model recalibration reducing the reported removal estimate.
Eligibility Requirements
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.
✓
Basalt or silicate mineral application metered at ±5% mass accuracy per hectare, with feedstock particle size specification documented
✓
Site-specific reactive transport weathering model submitted at registration, calibrated against soil porewater alkalinity sampling at each verification
✓
Trace metal content assay of the mineral feedstock (nickel, chromium) confirming compliance with DNSH thresholds
✓
Ten-stage registration process completed, from hybrid eligibility assessment through validation to ongoing verification, per THS Module 6
✓
Seventeen-element Project Design Document submitted, including a three-layer baseline analysis (biological, technology, combined system)
✓
Three-test additionality demonstrated, distinguishing deliberate carbon-removal-purpose mineral application from incidental agricultural lime use
✓
Non-Permanence Risk Rating (NPRR) assessed by an accredited VVB at validation; buffer pool contribution of 2–10% applied to gross verified credits
✓
Crop yield and soil health monitoring plan in place, both as a co-benefit indicator and a cross-check against unintended agricultural impacts
✓
Do No Significant Harm review covering soil health, biodiversity, water resources, and food security per Module 5
✓
Farmer or land manager consent and benefit-sharing agreement documented where the registering entity differs from the land occupier
Co-Benefits & SDGs
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.
SDG 2 · Zero Hunger
SDG 13 · Climate Action
SDG 15 · Life on Land
SDG 12 · Responsible Consumption & Production
Soil Health+
Projects with verified soil pH improvement and micronutrient availability gains, documented through registered soil testing, are eligible for the Soil Health+ label — one of the eight THS co-benefit designations.
Frontier Hybrid
Projects using novel integrated weathering-agriculture monitoring approaches with independently peer-reviewed methodology are eligible for the Frontier Hybrid label.
Reduced Fertiliser+
Farms demonstrating measured reductions in synthetic fertiliser or lime input, attributable to the micronutrient and pH benefits of silicate weathering, are eligible for this co-benefit label.
Smallholder Inclusion+
Projects aggregating smallholder farms with fair benefit-sharing agreements and technical support for weathering application are eligible for the Smallholder Inclusion co-benefit label.
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.