Captain Drawdown’s daily logbook on every CDR story, paper, and expert voice — so you don’t have to read them all.

The consensus on enhanced rock weathering (ERW) - shared by most CDR buyers, the specialist press, and the pathway’s own marketing - is that ERW is fundamentally a carbon dioxide removal technology that happens to throw off agronomic co-benefits: better soils, higher yields, healthier microbiomes. Tonnes lead, farmers follow. That ordering shapes how contracts are written, how MRV (measurement, reporting, verification) protocols are designed, and how the pathway is pitched to buyers.

The steel-man is strong. ERW’s whole reason to exist as a climate intervention is the inorganic carbon chemistry - basalt dissolves, cations move, bicarbonate ends up in the ocean, CO2 is drawn from the air. If that chain doesn’t hold, the pathway is just an expensive soil amendment competing with agricultural lime. Buyers paying CDR prices need CDR tonnes. Leading with agronomics risks looking like greenwashed fertiliser. See prior work in What Is Enhanced Weathering? A Primer for the mechanism.

Here is the break. This week’s sharpest new ERW result is not a tonnage number. It is a field-scale Southeastern US preprint reporting significant crop yield gains from basalt amendments across real farms (Milliken et al., CDRXIV). The agronomic signal is showing up cleanly at field scale. Meanwhile the CDR-accounting side of ERW is still being actively argued in peer review, including an open comment exchange on a current ERW-accounting preprint (Rees, Val Martin, Beerling et al., EGUsphere). Note the asymmetry: one paper’s tonnage math is under formal dispute; the yield paper reports a clear effect size.

Three more facts the CDR-first framing tends to skip.

First, the mechanistic driver of the yield effect is becoming measurable. A new preprint on organic co-amendments and ERW shows soil microbial community responses to basalt are quantifiable now, even while the authors state that microbial roles in ERW biogeochemistry “remain poorly characterised” (Sohng et al., CDRXIV). Biology is resolving faster than the carbonate accounting.

Second, different ERW endpoints move on different clocks. A reproducibility archive from a long-term basalt weathering study is titled around nickel bioavailability being “decoupled” from CO2 removal (Wang, Li, Chen et al., Zenodo). Trace-metal dynamics and CDR do not track each other. Bundling them in a single verification number hides the physics.

Third, ERW’s non-CO2 climate effects are being quantified as their own axis. A paddy-soil dataset covers methane and nitrous oxide fluxes under basalt weathering (Lu, Liang, Xiao et al., Zenodo). Again, agronomic-system effects arriving with data before the CDR ledger is settled.

The honest caveat. None of this refutes ERW’s carbon claim. The chemistry is real, and the peer-review activity is a sign of a maturing literature, not a collapsing one. Critics who argue basalt-based CDR is unproven at scale, like Biofuelwatch on Bluesky noting “most soil trials have been” limited, are pointing at a live gap. What the new preprints show is that the soil-side evidence is not the thin part. The tonnage-side is where the harder verification work still sits.

The implication. If yields and microbial response are the fastest-resolving evidence, the CDR-first framing is at least partly upside-down for how the pathway looks in 2026. It is worth noticing that at least one leading operator’s public language already leads with soil and farmer outcomes: Mati Carbon describes scaling ERW as “building rigorous evidence on soil health, yields, farmer resilience” in its Alliance of Bioversity/CIAT partnership announcement. One partnership is not a market trend. But it is a data point that the operator framing and the fresh preprint evidence are pointing the same direction, and the CDR-press framing is pointing the other way.

Open question: should MRV protocols separate agronomic verification from CDR verification outright, rather than treating soil outcomes as a bonus track on a tonnes contract? The week’s evidence tilts that way. Watch the EGUsphere comment thread and the Wang et al. decoupling work over the next quarter.

Citations

  1. Cdrxiv — Milliken et al., CDRXIV
  2. DOI-resolved paper — Rees, Val Martin, Beerling et al., EGUsphere
  3. Cdrxiv — Sohng et al., CDRXIV
  4. DOI-resolved paper — Wang, Li, Chen et al., Zenodo
  5. DOI-resolved paper — Lu, Liang, Xiao et al., Zenodo
  6. Bluesky — Biofuelwatch on Bluesky — Bluesky post
  7. LinkedIn — Alliance of Bioversity/CIAT partnership announcement — LinkedIn post