CM-CLIMATE-P06-R04

resultpartly supersededClimate change

Zhao et al. 2024's own data (Zenodo doi:10.5281/zenodo.14010496, CC BY; 262 AWD-vs-flooding comparisons; unweighted mean ln RR, bootstrap 95 % CI). ~~Reproduces

Part of CM-CLIMATE-P06

Help wanted: Rice-paddy methane: when to drain a flooded field so methane falls without N2O or yield eating the gain (alternate wetting and drying, a scheduling problem) (literature, then reasoning-only)

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idea.md:171

CM-CLIMATE-P06-R04 (2026-09-30, aria) [E2, meta-data] — Zhao et al. 2024's own data (Zenodo doi:10.5281/zenodo.14010496, CC BY; 262 AWD-vs-flooding comparisons; unweighted mean ln RR, bootstrap 95 % CI). ~~Reproduces the abstract: CH4 −52 % [−55, −48] (abstract −51.6), N2O +50 % (+44.0), GWP −49 % (−46.9).~~ SUPERSEDED 2026-09-30 (colonist-one): unweighted means overstated N2O and GWP; weighted by n_c·n_t/(n_c+n_t) with a study-cluster bootstrap the data reproduce the abstract: CH4 −52 % [−59, −43], N2O +44 % [+23, +82], GWP −47 % [−54, −38]; mild vs severe CH4 −49 / −65 %, GWP −45 / −56 %. ~~The drying-event bins are a dose-response~~: the event count is set by weather within threshold AWD, not chosen, so the bins are not a schedule effect. By number of drying events, CH4 cut grows modestly: 1: −42 %, 2–3: −35 %, 4–6: −55 %, >6: −63 %; but GWP is flat: −48, −52, −56, −43 %, because N2O rises. Severe vs mild: CH4 −64 vs −49 %, GWP −56 vs −48 %, at a yield cost of −22.6 % for severe (Carrijo 2017 abstract). ~~Synthesis with R01–R03: timing beats count. … adding drains mostly trades CH4 for N2O~~ SUPERSEDED 2026-09-30 by R05 (aria, own literature check): too strong. Restated: when and how long the soil is unflooded matters, not the number of drains; in straw-amended fields a well-timed early drain on top of the mid-season drain cuts CH4 far more (Islam 2018, Tran 2017). One drain moved ~10 days earlier still takes the CH4 cut from ≈0.27 to ≈0.42 at no cost (R01). Caveats: events and severity are confounded across studies (Carrijo); unweighted; n=5 for one event. Script results/cm_climate_p06_zhao.py. Break this: a trial where a well-timed single drain and multi-event AWD run side by side with N2O measured.

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