Methane production and its fate in paddy fields stV. Fate of Methane Remaining in Paddy Soil at Harvesting Stage

Abstract

The fate of CH4in paddy soil at the harvesting stage was studied in pot experiments. The amount of CH4retained in soil at the harvesting stage before drainage corresponded to 4–6% of the total amount of CH4emitted to the atmosphere throughout the growth period. Almost all of the CH4in soil was released to the atmosphere within 3 d after drainage in the rice-planted treatments, while CH4was hardly released in the fallow pot without development of cracks. When cracks developed, an amount of CH42.8 times as large as that emitted throughout the growth period was released in the fallow pot. Harvesting without drainage, which was considered to accelerate the senescence of roots, did not influence the CH4emission rates. The small increase of CH4emission rates by transferring pots into the phytotron (daytime: 30°C, night time: 25°C) from the open air (14–25°C) indicated that the temperature was not the major factor for the low CH4emission rates at the harvesting stage before drainage. © Taylor & Francis Group, LLC.