Claims checked › Claim
No-till sequesters carbon
“Switching to no-till locks carbon into the soil and fights climate change.”
Surface soil does gain carbon under no-till. Whether that is new carbon or carbon moved up from deeper layers is genuinely disputed, and most trials cannot tell because they never sample below 30 cm.
Where it comes from
A large literature showing higher soil organic carbon in the top layer under no-till, amplified by carbon-credit schemes and by input companies whose products fit no-till systems.
Who benefits
Carbon-credit developers, and the makers of the herbicides that no-till systems depend on. The most confident material on glyphosate and no-till online is published by the Glyphosate Renewal Group, an industry body. Cite it as a position, never as neutral evidence.
What the evidence says
The dispute is about sampling depth. Where trials sample the whole profile, the surface gain under no-till is often offset by losses deeper down, so the result may be redistribution within the profile rather than net sequestration (Powlson et al. 2014, discussed here). A paired-experiment meta-analysis found no-till's sequestration effect small and confined to particular systems (meta-analysis). Only about a quarter of tillage experiments sample below 30 cm, so most of the literature structurally cannot detect the deep loss (CarbonPlan). Results also shift between fixed-depth and equivalent-soil-mass accounting. Spain's 2025 government evaluation of its direct-seeding eco-scheme still reports a positive carbon difference, "with differences between sources" (see the funding page).
What to say instead
Recommend no-till with residue retention for water, structure and erosion, where the evidence is good and the Spanish evaluation confirms farmers adopt it for profitability. Treat the carbon benefit as contested and depth-dependent, and do not use it to sell the practice or to underwrite carbon credits. Details on the no-till page.