How do rice AWD carbon credits account for nitrous oxide from fertiliser?
VM0051 v1.1 makes farmers record all nitrogen inputs in farm logbooks. If fertiliser use rises, default IPCC-based calculations add the extra nitrous oxide. If a farm only switches to wetting and drying, a separate correction factor covers the small rise from dry spells. ICVCM calls the approach practical and conservative.
Why nitrous oxide matters
Methane falls when a paddy is drained between floods, because less organic matter breaks down without oxygen. Dry spells let air back into the soil, which can raise nitrous oxide. A credit that ignores this would overstate the gain.
What the methodology requires
- All nitrogen inputs go into farm logbooks, which makes fertiliser use visible.
- Where nitrogen inputs increase, default calculation methods estimate the added nitrous oxide.
- Where a project moves to wetting and drying without changing nitrogen inputs, a correction factor accounts for the partial increase. ICVCM expects this to be the most common case.
Where the numbers come from
The default values are based on the IPCC Guidelines (2019). They cover synthetic fertilisers, organic amendments and crop residues, and are meant to be a practical and conservative way to count extra nitrous oxide.
What a farmer group should start doing
- Log every fertiliser purchase and application, by field and date.
- Keep the same logbook before and after the switch, so the comparison holds.
- Do not change fertiliser rates in the first season without noting it.
What Senseible does here
Senseible does not issue or verify carbon credits and is not a registry. It gives carbon credit eligibility signals from your own records and keeps those records in order for a verifier. Verified here means rule checks passed against the evidence, not third-party assurance.
Last reviewed 2026-11-04.