Transcript Document 7562987

Greenhouse Gases Emissions and Mitigation
from Rice Production
Kruamas Smakgahn*, Tamon Fumoto and Kazuyuki Yagi
National Institute for Agro-Environmental Sciences
Tsukuba, Ibaraki, Japan
E-mail: [email protected]
Contents
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Background
Objectives
Introduction to models
Results
Models validation
Sensitivity test
Conclusions
Natural Sources of Atmospheric Methane
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http://www.epa.gov/methane/sources.html
Methane emissions from rice fields.
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Source: http://www.riceweb.org/reserch/Res.issmethane.htm
Methane is emitted to the
atmosphere from
wetlands via three
primary modes:
(i) diffusion of dissolved
methane across the waterinterface,
(ii) bubble ebullition, and
(iii) air circulation
between the atmosphere
and buried tissues of
aquatic plants, with the
stems and leaves serving
as conduits.
Natural Sources of Atmospheric N2O
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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.
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Agricultural activities and animal production systems are the largest
anthropogenic sources of these emissions.
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N2O emissions from agricultural soils occur through the nitrification and
denitrification of nitrogen in soils, particularly that from mineral or
organic fertilizers.
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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
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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
The process base model:
De-Nitrification
De-composition model
Schematic descriptions of soil
Biogeochemistry sub-models
Source: R.A.J. Plant 1998
Source: Fumoto et al. (Submitted GCB)
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
soil properties of study sites
Site
Soil name
Soil
taxonomy
Soil
texture
Carbon
(%)
Total N
(%)
Available
N (µg N g1)
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
<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
<1
6.6
Rice cultivation with rice straw incorporation
100
Revised DNDC model
DNDC model
Observation
60
40
20
rin
Su
t
Sp
r
Sp
l
Pn
ra
e
Ph
Kk
n
0
Bk
n
CH4 (g/m 2 /season)
80
Study sites
The revised DNDC model, which is modified
by focusing on electron donors
presented in soils, yielded appropriated results
compared with the original DNDC model
Seasonal CH4 emission (kgC/ha)
Rice cultivation without rice straw incorporation
120
Revised DNDC model
DNDC model
Observation
Samutsakorn
100
80
60
40
20
0
CF
LM
MS
MTD
400
Revised DNDC model
DNDC model
Observation
Singburi
Root C (kgC/ha)
Seasonl CH4 emission (kgC/ha)
Water managements
300
200
100
0
Urea
Ap
As
Fertilizer application
NT
NF
1500
Samutsakorn_CF
1000
500
0
220
240
260
280
300
320
340
360
Effect of soil properties
Sensitivity test : Fe+3 contents
Samutsakorn
20
15
2
CH4 (g/m /season)
25
10
5
0
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
Reducible Fe 3+ (mol/kg)
The results clearly indicate that the revised DNDC model
is highly sensitive to reducible Fe+3 concentration in soil.
Less available reducible iron in soil enhances methane emission
CH4 production was suppressed almost completely during ferric iron
reductions.
Soil Clay Contents
Samutsakorn
10
2
CH4 (g/m /season)
15
5
0
(Org.) 0.03 0.06 0.09 0.14 0.19 0.27 0.34 0.40 0.43 0.49
0.06
Soil clay content (%)
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
Effect of rice straw incorporation
Methane emission under with and without rice straw
incorporation
80
2
CH4 (g/m /season) .
70
Revised DNDC_without rice straw
Revised DNDC_with rice straw
Observed_with rice straw
60
50
40
30
20
10
0
Bkn
Kkn
Phrae
Pnl
Spr
Spt
Surin
Study site
Rice cultivation without rice straw incorporation help methane mitigation by 60-90 %.
Sanphatong
Revised DNDC_With RS
Revised DNDC_No RS
Observed_With RS
700
Sensitivity tests:
600
Soil Eh (mV) .
500
Rice straw incorporation
400
300
200
100
Sanphatong
0
-100 0
100
200
300
400
500
600
700
800
CH4 (g/m2/season)
-200
-300
Julian day (1993-1994)
35
30
25
20
15
10
5
0
No
straw
Sanphatong
SOC (kgC/ha) .
40000
500
1000
1500
2000
2500
3000
Rice straw (ton C/ha)
With RS
No RS
35000
-Rice straw incorporated into soil significantly
enhanced CH4 emission.
30000
25000
20000
0
100 200 300 400 500 600 700 800
Julian day (1993-1994)
- Correlation between rice straw incorporation
and methane emission is linear form
CH4 (kgC/ha/day)
Effect of rice cultivar
Rice root
16
14
12
10
8
6
4
2
0
200
400
600
800
1000
1200
1400
1600
Suphanburi 1991
0
100
200
300
400
Julian day
Rice root biomass directly influences estimation of methane emission
- Rice root is a major source of electron donor (DOC) for methane
production
Methane and biomass
Sanphatong_15 VI
2500
Biomass (kgC/ha) .
Biomass (kgC/ha) .
Sanphatong_3 VI
2500
2000
1500
1000
y = 8.0764x + 626.29
2
R = 0.9548
500
0
2000
1500
1000
y = 17.919x + 884.15
500
R2 = 0.9349
0
0
50
100
150
Methane (kgC/ha)
200
0
20
40
Methane (kgC/ha)
60
80
Effect of water management
Field drainage
Seasonal CH emission (kgC/ha) .
35
Vegetative stage
Panicle initiation
30
Flowering stage
25
20
15
10
5
0
3
5
7
10
Drainage period (day)
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.
Total N2 O emission (gN ha)
Nitrous oxide from different water managements
150
Revised DNDC model
DNDC model
Observation
Samutsakorn
100
50
0
CF
LM
MS
Water managements
Drainage treatments emitted high N2O
MTD
Total N 2 O emissions (gN ha -1 )
Simulated N2O from different type of
fertilizer applications
2
Singburi
Revised DNDC model
1.5
1
0.5
0
Urea
Ap
NT
As
NF
Fertilizer application
High N contained fertilizer enhances N2O emission
Conclusions
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The sensitivity analysis suggested that soil properties such as
Fe+3 contents, rice straw incorporation and field drainage
are the main factors influence on CH4 emission
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Field drainage and fertilizer application influence on N2O
emission
Mitigation options
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Possible mitigation options
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1) Reduce amount of rice straw incorporation into rice soil,
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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.
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3) Fertilizer application
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4. Rice cultivar
Acknowledgements
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This research was funded by the grant of Eco-Frontier
Fellowship program by Ministry of the Environment, Japan.
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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.
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