What permanence should we credit to soil carbon?
An illustrative format example from the soil carbon prototype, not independently verified research or a client deliverable. Sources are named for attribution, not as Martlet partners or endorsers.
Every claim carries a flag and a source.
Disclosure: Guy Hudson, Martlet’s founder, chairs Loam Bio. This example includes Loam material and studies involving Loam. The rights and agreement labels demonstrate the format and do not establish signed contributor permission or an independent assessment of Loam.
The field broadly agrees.
The field is split. Both sides are named.
A minority position, never the headline.
A superscript like [S1] links to the source panel and the named work a claim is drawn from.
Soil carbon is real, and it is reversible.
Soil carbon persistence depends on continuing movement and transformation within soils. Scientific and policy definitions of permanence do not always align.[S1]
S1 · Dynarski, Bossio & Scow
Evidence supports soil carbon saturation, with greater sequestration efficiency in soils further from saturation. Capacity varies with soil and conditions.[S13]
S13 · Stewart, Paustian, Conant, Plante & Six
Particulate and mineral-associated organic matter differ in persistence. The fraction receiving a carbon gain matters when assessing its durability.[S17]
S17 · Lavallee, Soong & Cotrufo
Can soil carbon be made durable enough to credit?
This is contested, so we do not resolve it. Both camps are placed side by side, with the strongest version of each.
Apparent no-till gains are largely a change in depth distribution, not net sequestration. The mitigation value is widely overstated.[S2]
Because soil carbon is impermanent, it cannot truly offset durable fossil-fuel emissions. Treating that gap as closed is a category error.[S5]
Powlson et al. · Saifuddin et al.
A fungal inoculum can shift sequestered carbon toward more stable, mineral-associated fractions.[S14]
In controlled trials the resistant carbon pool rose 20.94% (p<0.001), with fungal necromass producing negative priming. This is mechanism support, held apart from the field results.[S14]
The prototype also records company field results of +5.01 tCO2e/ha (p=0.14) and +7.56 tCO2e/ha (p=0.07). These are directionally positive but not statistically significant. [S14]
In Loam’s reviewed field-trial fractionation, about 75% of the carbon built over two years was mineral-associated.[S18] This is a striking figure, from the developer’s own data. It is on the record, and it is not used to carry the conclusion while the wider field’s spread does not support it.
Click any citation and this is what you see.
Katherine A. Dynarski, Deborah A. Bossio & Kate M. Scow
Dynamic Stability of Soil Carbon: Reassessing the 'Permanence' of Soil Carbon Sequestration (2020)
Read the published source →- Standing
- Synthesis of the persistence/permanence literature
- Stance
- Dynamic stability and policy definitions
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Named as a published source. No Martlet contribution or endorsement implied.
David Powlson et al.
Limited potential of no-till agriculture for climate change mitigation (2014)
Read the published source →- Standing
- Senior soil scientist. led international review
- Stance
- Sceptic: mitigation overstated
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Named as a published source. No Martlet contribution or endorsement implied.
Saifuddin et al.
Soil carbon offset markets are not a just climate solution (2024)
Read the published source →- Standing
- Peer-reviewed critique
- Stance
- Strong sceptic: not a fossil offset
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Named as a published source. No Martlet contribution or endorsement implied.
Catherine E. Stewart, Keith Paustian, Richard T. Conant, Alain F. Plante & Johan Six
Soil carbon saturation: concept, evidence and evaluation (2007)
Read the published source →- Standing
- Foundational saturation-concept research
- Stance
- Saturation science
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Named as a published source. No Martlet contribution or endorsement implied.
Loam Bio
CarbonBuilder 2026 Technical Manual (2026)
Company website, not the underlying document →- Standing
- Developer applying the stable-fraction thesis commercially. trials with USYD, WSU, UQ
- Stance
- Developer: durability is engineerable
- Rights
- Illustrative rights record. Pending Loam sign-off. No executed permission evidenced.
- Context
- Company material. Guy Hudson chairs Loam Bio. Prototype figures have not been independently verified for this example.
Emiko K. Stuart, Laura Castañeda-Gómez, Wolfram Buss, Jeff R. Powell & Yolima Carrillo
Non-mycorrhizal root-associated fungi increase soil C stocks and stability via diverse mechanisms (2024)
Read the published source →- Standing
- Peer-reviewed controlled mechanism study
- Stance
- Mechanism support in controlled conditions
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Used isolates screened by Loam Bio. Funded by Western Sydney University and SoilCQuest2031. This is not independent replication of commercial field outcomes.
Yolima Carrillo, Emiko K. Stuart & Jeff R. Powell
Necromass of Diverse Root-Associated Fungi Suppresses Decomposition of Native Soil Carbon via Impacts of Their Traits (2025)
Read the published source →- Standing
- Peer-reviewed laboratory mechanism study
- Stance
- Mechanism support in controlled conditions
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- The publication discloses support from Loam Bio, SoilCQuest and Western Sydney University, and Loam-screened isolates. This is not independent commercial field validation.
Jocelyn M. Lavallee, Jennifer L. Soong & M. Francesca Cotrufo
Conceptualizing soil organic matter into particulate and mineral-associated forms to address global change in the 21st century (2020)
Read the published source →- Standing
- Canonical framework for soil-carbon fractions
- Stance
- Framework: fractions differ in persistence
- Rights
- Cited, not cleared under a Martlet contributor agreement.
- Context
- Named as a published source. No Martlet contribution or endorsement implied.
Loam Bio
Durable Carbon Removal at Scale (2026)
Company website, not the underlying document →- Standing
- Developer strategy/marketing deck presenting CarbonBuilder field results and crediting approach
- Stance
- Developer: durable removal at scale
- Rights
- Illustrative rights record. Pending Loam sign-off. No executed permission evidenced.
- Context
- Company material. Guy Hudson chairs Loam Bio. Prototype figures have not been independently verified for this example.
Source metadata has been checked where publisher records are available. This remains an illustrative extract, with no claim that named authors have reviewed or endorsed it. Loam documents are represented by source records, not reproduced here.
The evidence that would change our reading.
- →Independent, multi-year re-measurement of the mineral-associated fraction on working farms, not company strip trials.
- →A crediting standard that prices impermanence directly, rather than crediting a 100-year claim against a buffer pool.
- →Field results at scale that hold up once soils approach saturation.
See how dated claims would be tracked in the illustrative resolution ledger. Want a report like this on your own question? Discuss a pilot.