What permanence should we credit to soil carbon?
A redacted extract, not a live deliverable. It shows how a Martlet answer reads: claims traced to named sources, the field's disagreement kept on the page, and the calls that will settle in time marked as such.
Every claim carries a flag and a source.
The field broadly agrees.
The field is split; both sides are named.
A minority position, never the headline.
A superscript like [S1] points to the source panel — the named work a claim is drawn from.
Soil carbon is real, and it is reversible.
Soil carbon is dynamic, and even physicochemical protection is reversible — long-term persistence cannot be assumed.[S1]
S1 · Dynamic-stability review (Frontiers in Environmental Science)
Soils have a finite carbon-saturation capacity; as they approach it, additional sequestration falls toward zero.[S13]
S13 · Stewart, Paustian, Conant & Six
Soil organic matter splits into particulate matter, persisting years to decades, and mineral-associated matter, persisting decades to centuries — so permanence depends on which pool the carbon lands in.[S17]
S17 · Lavallee & 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 — mechanism support, held apart from the field results.[S14]
Loam Bio (developer) · independent replication at S15, S16
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.
Loam Bio
- Standing
- Agricultural biotechnology developer applying the stable-fraction thesis commercially; trials with USYD, WSU, UQ.
- Stance
- Developer — durability is engineerable
- Rights
- Cleared
David Powlson et al.
- Standing
- Senior soil scientist, Rothamsted Research; led an international review.
- Stance
- Skeptic — mitigation overstated
- Rights
- Public — cited, not reproduced
The incentive behind a source sits next to its claims, in plain sight — a developer’s own trial data is labelled as such, and read alongside independent work.
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.
Two claims in this extract resolve in time and sit on the resolution ledger. Want a report like this on your own question? Commission one.