Dataset Information

Acclimation of methane emissions from rice paddy fields to straw addition.

ABSTRACT: Straw incorporation is a common long-term practice to improve soil fertility in croplands worldwide. However, straw amendments often increase methane (CH4) emissions from rice paddies, one of the main sources of anthropogenic CH4. Intergovernmental Panel on Climate Change (IPCC) methodologies to estimate CH4 emissions from rice agriculture assume that the effect of straw addition remains constant over time. Here, we show through a series of experiments and meta-analysis that these CH4 emissions acclimate. Effects of long-term (>5 years) straw application on CH4 emissions were, on average, 48% lower than IPCC estimates. Long-term straw incorporation increased soil methanotrophic abundance and rice root size, suggesting an increase in CH4 oxidation rates through improved O2 transport into the rhizosphere. Our results suggest that recent model projections may have overestimated CH4 emissions from rice agriculture and that CH4 emission estimates can be improved by considering the duration of straw incorporation and other management practices.

SUBMITTER: Jiang Y

PROVIDER: S-EPMC6357747 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Acclimation of methane emissions from rice paddy fields to straw addition.

Jiang Yu Y Qian Haoyu H Huang Shan S Zhang Xingyue X Wang Ling L Zhang Li L Shen Mingxing M Xiao Xiaoping X Chen Fu F Zhang Hailin H Lu Changying C Li Chao C Zhang Jun J Deng Aixing A van Groenigen Kees Jan KJ Zhang Weijian W

Science advances 20190116 1

Straw incorporation is a common long-term practice to improve soil fertility in croplands worldwide. However, straw amendments often increase methane (CH4) emissions from rice paddies, one of the main sources of anthropogenic CH4. Intergovernmental Panel on Climate Change (IPCC) methodologies to estimate CH4 emissions from rice agriculture assume that the effect of straw addition remains constant over time. Here, we show through a series of experiments and meta-a ...[more]

PMID: 30746466

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Project description:Paddy rice fields are one of the most important sources of anthropogenic methane. Improving the accuracy in the CH4 budget is fundamental to identify strategies to mitigate climate change. Such improvement requires a mechanistic understanding of the complex interactions between environmental and agronomic factors determining CH4 emissions, and also the characterization of the annual temporal CH4 emissions pattern in the whole crop cycle. Hence, both the growing and fallow seasons must be included. However, most of the previous research has been based on single-factor analyses that are focused on the growing season. In order to fill this gap, a study was conducted in a Mediterranean rice agrosystem (Ebre Delta, Catalonia) following a farm-to-farm approach with the purpose of 1) evaluating the cumulative and temporal pattern of CH4 emission, and 2) conducting a multi-variate analyses to assess the associative pattern, relative contribution and temporal variation of the main explanatory variables concerning the observed CH4 emissions. Measurements of CH4 emissions and agronomic and environmental parameters in 15 commercial rice fields were monitored monthly, during a whole crop field cycle. The temporal pattern of CH4 emission followed a bi-modal distribution peaking in August and October. The cumulative annual CH4 emissions from rice fields amounted 314 kg CH4 kg ha-1, of which ca. 70% were emitted during the fallow season. The main controlling factors of the CH4 emission rate in the growing season were positive related to water level and plant cover, while soil redox was negatively related. The main controlling factors in the fallow season were water level (negatively related, conversely to the growing season), as well as straw incorporation and soil temperature (positively related). The results of this study highlight the importance of the often neglected fallow season in the accurate estimation of CH4 emissions and, thus, the necessity of measurement programs that cover the whole crop field cycle. This information is the first step for setting effective mitigation strategies based on straw and water management.

Project description:Rice straw is a major substrate for the production of methane, a greenhouse gas, in flooded rice fields. The bacterial community degrading rice straw under anoxic conditions was investigated with molecular methods. Rice straw was incubated in paddy soil anaerobically for 71 days. Denaturing gradient gel electrophoresis (DGGE) of the amplified bacterial 16S rRNA genes showed that the composition of the bacterial community changed during the first 15 days but then was stable until the end of incubation. Fifteen DGGE bands with different signal intensities were excised, cloned, and sequenced. In addition, DNA was extracted from straw incubated for 1 and 29 days and the bacterial 16S rRNA genes were amplified and cloned. From these clone libraries 16 clones with different electrophoretic mobilities on a DGGE gel were sequenced. From a total of 31 clones, 20 belonged to different phylogenetic clusters of the clostridia, i.e., clostridial clusters I (14 clones), III (1 clone), IV (1 clone), and XIVa (4 clones). One clone fell also within the clostridia but could not be affiliated to one of the clostridial clusters. Ten clones grouped closely with the genera Bacillus (3 clones), Nitrosospira (1 clone), Fluoribacter (1 clones), and Acidobacterium (2 clones) and with clone sequences previously obtained from rice field soil (3 clones). The relative abundances of various phylogenetic groups in the rice straw-colonizing community were determined by fluorescence in situ hybridization (FISH). Bacteria were detached from the incubated rice straw with an efficiency of about 80 to 90%, as determined by dot blot hybridization of 16S rRNA in extract and residue. The number of active (i.e., a sufficient number of ribosomes) Bacteria detected with a general eubacterial probe (Eub338) after 8 days of incubation was 61% of the total cell counts. This percentage decreased to 17% after 29 days of incubation. Most (55%) of the active cells on day 8 belonged to the genus Clostridium, mainly to clostridial clusters I (24%), III (6%), and XIVa (24%). An additional 5% belonged to the Cytophaga-Flavobacterium cluster of the Cytophaga-Flavobacterium-Bacteroides phylum, 4% belonged to the alpha, beta, and gamma Proteobacteria, and 1.3% belonged to the Bacillus subbranch of the gram-positive bacteria with a low G+C content. The results show that the bacterial community colonizing and decomposing rice straw developed during the first 15 days of incubation and was dominated by members of different clostridial clusters, especially clusters I, III, and XIVa.

Dataset Information

Acclimation of methane emissions from rice paddy fields to straw addition.

Publications

Acclimation of methane emissions from rice paddy fields to straw addition.

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