Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
04 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
How methane emission from rice paddy is affected by management practices and region?
Jinyang Wang1,2, Hiroko Akiyama3, Kazuyuki Yagi3, and Xiaoyuan Yan1 1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China
2Environment Centre Wales, School of the Environment, Natural Resources and Geography, Bangor University, Bangor LL57 2UW, UK
3Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Abstract. Rice cultivation has long been known as one of the dominant anthropogenic contributors to methane (CH4) emissions, yet there is still uncertainty when estimating its emissions at the global/regional scale. An increasing number of rice field measurements have been conducted globally, which allow us to assess the major variables controlling CH4 emissions and develop the region- and country-specific emission factors (EFs). Results shown that the CH4 flux from rice fields were closely related to organic amendment, water regime during and before the rice-growing season, soil properties and climate. The average CH4 flux from fields with single and multiple drainages were 71 % and 55 % of that from continuously flooded rice fields. The CH4 flux from fields that were flooded in the previous season were 2.4 and 2.7 times that from fields previously drained for a short and long season. Contrary to the previously reported optimum soil pH of around neutrality, paddy soils with pH of 5.0–5.5 gave the maximum CH4 emission. Rice straw applied at 6 t ha−1 shortly before rice transplanting can increase CH4 emission by 3.2 times, while it increases CH4 emission by only 1.6 times when applied in the previous season. The default EF was estimated to 1.19 kg CH4 ha−1 d−1 with a 95 % confidence interval of 0.80 to 1.76 kg CH4 ha−1 d−1 for continuously flooded rice fields without organic amendment and with a preseason water status of short drainage. The default EFs at sub-regional and country levels were also estimated. We conclude that these default EFs and scaling factors can be used to develop national or regional emission inventories.
Citation: Wang, J., Akiyama, H., Yagi, K., and Yan, X.: How methane emission from rice paddy is affected by management practices and region?, Atmos. Chem. Phys. Discuss.,, in review, 2018.
Jinyang Wang et al.
Jinyang Wang et al.
Jinyang Wang et al.


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Short summary
Through reassessing the controlling variables and emission factors (EF) of CH4 on a global scale, we find that the global default EF of CH4 is lower and has a narrow error range than previous studies. The region/country-specific EFs are for the first time developed. The findings of major controlling variables on CH4 emission may help to devise mitigation strategies at different scales. Together, this study can provide a sound basis for developing CH4 national inventories and mitigation options.
Through reassessing the controlling variables and emission factors (EF) of CH4 on a global...