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

Abstract

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.]