Reduce methane emission from rice paddies by man-made aerenchymatous tissues

Methane is the second most important greenhouse gas after carbon dioxide, and 8–11% is emitted from paddy fields. Methanogenic microbial processes in water-saturated soils can be alleviated through the oxygenation of soils, which may hamper methane production and emissions in paddies. Here, by mimicking O₂ release from rice roots, we report the use of man-made (i.e., silicone tube-based) aerenchymatous tissues (MAT) to continuously release O₂ to abate methane emission from paddies. High O₂-releasing rates (such as 5 kg O₂/ha/d) can be easily achieved by adjusting MAT density (e.g., 0.2 m² tube/m² soil) and its inner air pressure (e.g., 25 kPa). Following deployment, MAT significantly increased soil redox potential (from -150 mV to -88.6 mV) and induced active iron redox cycling. This decreased the availability of organic substrates of methanogens and therefore dramatically reduced their abundance (-25.1% active mcrA gene). We quantified the decrease in methane emission both in mesocosms and paddy field trials and found in both setups that ~ 50% of methane emission was reduced. Moreover, we showed that the performance of MAT can be further improved by simply increasing the air pressure in MAT (e.g., -74.2% methane emission at 200 kPa air pressure). This work provides a powerful and sustainable method for mitigating methane emission from rice paddies. Graphical Abstract: [Figure not available: see fulltext.]