Plant Root Circadian Rhythms Drive Methane Production in Oxygen-Rich Soils
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A study published in Nature Geoscience reveals that circadian radial oxygen loss from plant roots induces redox oscillations in the rhizosphere that drive methane production in oxygen-rich soils — a previously unrecognized global methane source. At night, iron minerals in the soil are reduced; during the day, the Fe(II) produced overnight is re-oxidized, generating reactive oxygen species and oxo-iron(IV) complexes that demethylate organic substrates and release CH4 as a by-product. Using a random forest model, researchers estimate global CH4 production potential in rice rhizospheres at 0.7–3.3 Tg/year, representing 1.9–13.2% of total paddy CH4 emissions.
Technical significance
This discovery challenges the long-held assumption that methanogenesis is confined to anoxic environments. The estimated 0.7–3.3 Tg/year from rice paddies alone represents a significant gap in global methane budgets. For climate modeling, this means current estimates of agricultural methane emissions may be substantially undercounted. The mechanism — purely abiotic redox cycling driven by plant root biology — suggests this process operates across all aquatic plant rhizospheres, not just rice.