Greenhouse Gases Emissions and Mitigation from Rice Production

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Greenhouse Gases Emissions and Mitigationfrom
Rice Production

• Kruamas Smakgahn, Tamon Fumoto and Kazuyuki
  Yagi
•   National Institute for Agro-Environmental
  Sciences
• Tsukuba, Ibaraki, Japan
• E-mail smakgahn_at_affrc.go.jp

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Contents

• Background
• Objectives
• Introduction to models
• Results
• Models validation
• Sensitivity test
• Conclusions

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Natural Sources of Atmospheric Methane

• http//www.epa.gov/methane/sources.html

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Methane emissions from rice fields.

• Methane is emitted to the atmosphere from
  wetlands via three primary modes
• (i) diffusion of dissolved methane across the
  water-interface,
• (ii) bubble ebullition, and
• (iii) air circulation between the atmosphere and
  buried tissues of aquatic plants, with the stems
  and leaves serving as conduits.

Source http//www.riceweb.org/reserch/Res.issmeth
ane.htm
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Natural Sources of Atmospheric N2O

• Nitrous oxide (N2O) is a powerful greenhouse gas,
  about 310 times more effective at trapping heat
  than carbon dioxide on a molecule-for-molecule
  basis.
• Agricultural activities and animal production
  systems are the largest anthropogenic sources of
  these emissions.
• N2O emissions from agricultural soils occur
  through the nitrification and denitrification of
  nitrogen in soils, particularly that from mineral
  or organic fertilizers.
• Emissions are very dependent on local management
  practices, fertilizer types, and climatic and
  soil conditions,

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• Expanding cultivation areas of rice have
  significantly contributed to the increase in the
  concentration of atmospheric CH4 and N2O
  concentration
• It is difficult to measure emission in large
  scale and obtain mitigation options, thus model
  implementation is a promising options for
  predictions.

Objectives To simulate CH4 and N2 O emissions
from rice fields with varying cultivations
practice in different locations in order to
consider an accuracy of estimation To obtain
mitigation options of CH4 and N2O emissions from
rice fields
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The process base modelDe-Nitrification
De-composition model
Schematic descriptions of soil Biogeochemistry
sub-models
Source R.A.J. Plant 1998
Source Fumoto et al. (Submitted GCB)
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Location of study sites
locations of study site in Thailand 1. Rice
cultivation under rice straw incorporation (7
sites) Bangkok, Khon Kean, Phrae, Phitsanulok,
Sanphatong (Chiang Mai), Suphanburi and Surin
province 2. Rice cultivation without rice straw
incorporation (2 sites) Samutsakorn and Singburi
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soil properties of study sites
Site Soil name Soil taxonomy Soil texture Carbon () Total N () Available N (µg N g-1) Free Fe2 O3 (g kg-1) SO42- (µ g S mL-1) Soil pH (flooded)
Bangkhen Bangkhen (Bkn) Typic Tropaquepts Heavy clay 0.188 0.2 115 1.8 454 6.7
Khon Kaen Roi Et (Et) Aeric Paleaquults Sandy loam 0.049 0.002 37 0.1 lt 1 6.8

Phisanulok Alluvial complex Light clay 0.14 0.014 91 2.2 48 6.3
Phrae Lampang (Lp) Typic Paleaqualfs Silt clay loam 0.089 0.009 32 1.2 28 6.9
Samutsakorn Bangkok (Bk) Typic Tropaquepts Clay 1.31 0.06 No data No data No data 6.10
San Pa Thong Hang Dong (Hd) Typic Tropaquepts Light clay 0.103 0.011 49 1.5 29 6.9
Singburi Sanphaya (Sp) Aquic Ustifluvents Loam 0.78 0.06 No data No data No data 6.90
Suphaburi Phimai (Pm) Vertic Tropaquepts Clay 1.30 0.010 84 1.6 2-23 5.4-6.1
Surin Roi Et (Re) Aeric Paleaquults Sandy loam 0.049 0.003 35 0.8 lt 1 6.6
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Rice cultivation with rice straw incorporation
The revised DNDC model, which is modified by
focusing on electron donors presented in soils,
yielded appropriated results compared with the
original DNDC model
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Rice cultivation without rice straw incorporation
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Effect of soil properties
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Sensitivity test Fe3 contents
The results clearly indicate that the revised
DNDC model is highly sensitive to reducible Fe3
concentration in soil. Less available reducible
iron in soil enhances methane emission CH4
production was suppressed almost completely
during ferric iron reductions.
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Soil Clay Contents
High clay content in soil or heavy clay texture
is trended to mitigated CH4 emission Low clay
content in sandy soil, silt clay soil, silt clay
loam are not suitable for CH4 production
predicted by revised DNDC model
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Effect of rice straw incorporation
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Methane emission under with and without rice
straw incorporation
Rice cultivation without rice straw incorporation
help methane mitigation by 60-90 .
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Sensitivity tests Rice straw incorporation

• Rice straw incorporated into soil significantly
  enhanced CH4 emission.
• - Correlation between rice straw incorporation
  and methane emission is linear form

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Effect of rice cultivar
Rice root biomass directly influences estimation
of methane emission - Rice root is a major source
of electron donor (DOC) for methane production
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Methane and biomass
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Effect of water management
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Field drainage
Field drainage during growing period (i.e.
vegetative, panicle initial, and ripening stage)
reduced CH4 emissions Methane emission was
reduced under longer period of field
drainage. Methane reduction rate from field
drainage in vegetative period is higher than
other growth period under the same drainage
duration.
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Nitrous oxide from different water managements
Drainage treatments emitted high N2O
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Simulated N2O from different type of fertilizer
applications
High N contained fertilizer enhances N2O emission
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Conclusions

• The sensitivity analysis suggested that soil
  properties such as Fe3 contents, rice straw
  incorporation and field drainage are the main
  factors influence on CH4 emission
• Field drainage and fertilizer application
  influence on N2O emission

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Mitigation options

• Possible mitigation options
• 1) Reduce amount of rice straw incorporation into
  rice soil,
• 2) conduct field drainage during growing period.
• However, field drainage may induce weeds and
  possible to reduce rice grain yield. Therefore,
  optimum drainage period in optimum growth stage
  of rice plant needs to concern to obtain the
  practical mitigation option.
• 3) Fertilizer application
• 4. Rice cultivar

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Acknowledgements

• This research was funded by the grant of
  Eco-Frontier Fellowship program by Ministry of
  the Environment, Japan.
• We thanks Prof. C.S. Li for DNDC model.
• Sincere thanks to Prof. Shu Fukai, Dr. Naruo
  Matsumoto, Dr. Niwat Nadheerong, Mr. Chitnucha
  Buddhaboon for valuable data and their kindly
  suggestions on of Thai rice plants
  characteristics.