GGreenhouse Gases Emissions and Mitigationreenhouse Gases Emissions and Mitigation

from Rice Productionfrom Rice Production

Kruamas SmakgahnKruamas Smakgahn*, Tamon Fumoto and Kazuyuki Yagi*, Tamon Fumoto and Kazuyuki Yagi

    National Institute for Agro-Environmental SciencesNational Institute for Agro-Environmental SciencesTsukuba, Ibaraki, JapanTsukuba, Ibaraki, Japan

E-mail: smakgahn@affrc.go.jpE-mail: smakgahn@affrc.go.jp

ContentsContents

Background Background ObjectivesObjectives Introduction to modelsIntroduction to models ResultsResults

Models validationModels validationSensitivity testSensitivity test

ConclusionsConclusions

http://www.epa.gov/methane/sources.htmlhttp://www.epa.gov/methane/sources.html

Natural Sources of Atmospheric Methane

Methane is emitted to the Methane is emitted to the atmosphere from atmosphere from wetlands via three wetlands via three primary modes: primary modes:

(i) diffusion of dissolved (i) diffusion of dissolved methane across the water-methane across the water-interface, interface,

(ii) bubble ebullition, and (ii) bubble ebullition, and (iii) air circulation (iii) air circulation

between the atmosphere between the atmosphere and buried tissues of and buried tissues of aquatic plants, with the aquatic plants, with the stems and leaves serving stems and leaves serving as conduits. as conduits.

Source: http://www.riceweb.org/reserch/Res.issmethane.htm

Methane emissions from rice fields.Methane emissions from rice fields.

Nitrous oxide (NNitrous oxide (N22O) is a powerful greenhouse gas, about 310 times more O) is a powerful greenhouse gas, about 310 times more effective at trapping heat than carbon dioxide on a molecule-for-molecule effective at trapping heat than carbon dioxide on a molecule-for-molecule basis. basis.

Agricultural activities and animal production systems are the largest Agricultural activities and animal production systems are the largest anthropogenic sources of these emissions. anthropogenic sources of these emissions.

NN22O emissions from agricultural soils occur through the nitrification and O emissions from agricultural soils occur through the nitrification and denitrification of nitrogen in soils, particularly that from mineral or denitrification of nitrogen in soils, particularly that from mineral or organic fertilizers. organic fertilizers.

Emissions are very dependent on local management practices, fertilizer Emissions are very dependent on local management practices, fertilizer types, and climatic and soil conditions,types, and climatic and soil conditions,

Natural Sources of Atmospheric N2O

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 CHTo simulate CH44 and N and N22 O emissions from rice fields with varying cultivations O emissions from rice fields with varying cultivations

practice in different locations in order to consider an accuracy of estimationpractice in different locations in order to consider an accuracy of estimation

To obtain mitigation options of CHTo obtain mitigation options of CH44 and N and N22O emissions from rice fieldsO emissions from rice fields

The process base model:The process base model:De-Nitrification De-Nitrification

De-composition modelDe-composition model

Source: R.A.J. Plant 1998

Source: Fumoto et al. (Submitted GCB)

Schematic descriptions of soil Biogeochemistry sub-models

Location of study sitesLocation 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 g-

1)

Free Fe2

O3 (g kg-1)

SO42-

(µ g S mL-1)

Soil pH (flooded)

Bangkhen Bangkhen (Bkn)Bangkhen (Bkn) Typic Typic Tropaquepts Tropaquepts

Heavy clayHeavy clay 0.1880.188 0.20.2 115 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 incorporationRice cultivation with rice straw incorporation

0

20

40

60

80

100

Study sites

CH

4 (g

/m2 /s

easo

n)

Revised DNDC model

DNDC model

Observation

The revised DNDC model, which is modified The revised DNDC model, which is modified

by focusing on electron donors by focusing on electron donors

presented in soils, yielded appropriated results presented in soils, yielded appropriated results

compared with the original DNDC modelcompared with the original DNDC model

Rice cultivation without rice straw incorporationRice cultivation without rice straw incorporation

CF LM MS MTD0

20

40

60

80

100

120

Water managements

Sea

son

al C

H 4 e

mis

sio

n (

kgC

/ha) Samutsakorn

Revised DNDC modelDNDC modelObservation

Urea Ap As NT NF0

100

200

300

400

Fertilizer application

Sea

sonl

CH

4 em

issi

on (

kgC

/ha) Singburi

220 240 260 280 300 320 340 3600

500

1000

1500

Root

C (k

gC/h

a)

Samutsakorn_CF

Revised DNDC modelDNDC modelObservation

Effect of soil properties

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.

Sensitivity test : Sensitivity test : FeFe+3+3 contents contents

Samutsakorn

0

5

10

15

20

25

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)

CH

4 (g

/m2 /s

easo

n)

Soil Clay Contents

Samutsakorn

0

5

10

15

(Org.)0.06

0.03 0.06 0.09 0.14 0.19 0.27 0.34 0.40 0.43 0.49Soil clay content (%)

CH

4 (g

/m2 /se

ason

)

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 Methane emission under with and without rice straw incorporationincorporation

Rice cultivation without rice straw incorporation help methane mitigation by 60-90 %.

0

10

20

30

40

50

60

70

80

Bkn Kkn Phrae Pnl Spr Spt Surin

Study site

CH

4 (

g/m

2 /sea

son)

.Revised DNDC_without rice strawRevised DNDC_with rice strawObserved_with rice straw

Sanphatong

-300

-200

-100

0

100

200

300

400

500

600

700

0 100 200 300 400 500 600 700 800

Julian day (1993-1994)

Soil

Eh (m

V) .

Revised DNDC_With RSRevised DNDC_No RSObserved_With RS

Sanphatong

20000

25000

30000

35000

40000

0 100 200 300 400 500 600 700 800

Julian day (1993-1994)

SOC

(kgC

/ha)

.

With RSNo RS

-Rice straw incorporated into soil significantly enhanced CH4 emission.

- Correlation between rice straw incorporation and methane emission is linear form

Sensitivity tests: Sensitivity tests: Rice straw incorporationRice straw incorporation

Sanphatong

05

101520253035

Nostraw

500 1000 1500 2000 2500 3000

Rice straw (ton C/ha)

CH

4 (g

/m2 /s

easo

n)

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

0 100 200 300 4000

2

4

6

8

10

12

14

16

Julian day

CH

4 (

kgC

/ha/

day)

Suphanburi 19912004006008001000120014001600

Rice root

Methane and biomassMethane and biomass

Sanphatong_3 VI

y = 8.0764x + 626.29

R2 = 0.9548

0

500

1000

1500

2000

2500

0 50 100 150 200Methane (kgC/ha)

Bio

mas

s (kg

C/h

a) .

Sanphatong_15 VI

y = 17.919x + 884.15

R2 = 0.9349

0

500

1000

1500

2000

2500

0 20 40 60 80

Methane (kgC/ha)

Bio

mas

s (k

gC/h

a) .

Effect of water management

Field drainageField 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.

0

5

10

15

20

25

30

35

Seas

onal

CH

em

issi

on (

kgC

/ha)

.3 5 7 10

Drainage period (day)

Vegetative stage

Panicle initiation

Flowering stage

NitrousNitrous oxide from different water managementsoxide from different water managements

CF LM MS MTD0

50

100

150

Water managements

Tot

al N

2O e

mis

sion

(gN

ha) Samutsakorn Revised DNDC model

DNDC modelObservation

Drainage treatments emitted high N2O

Simulated NSimulated N22O from different type of O from different type of

fertilizer applicationsfertilizer applications

Urea Ap NT As NF0

0.5

1

1.5

2

Fertilizer application

Tota

l N2O

em

issio

ns (g

N h

a-1

)

SingburiRevised DNDC model

High N contained fertilizer enhances N2ON2O emission

ConclusionsConclusions

The sensitivity analysis suggested that soil properties such The sensitivity analysis suggested that soil properties such as Feas Fe+3+3 contents, rice straw incorporation and field drainage contents, rice straw incorporation and field drainage are the main factors influence on CHare the main factors influence on CH44 emission emission

Field drainage and fertilizer application influence on NField drainage and fertilizer application influence on N22O O

emissionemission

Mitigation optionsMitigation options

Possible mitigation optionsPossible mitigation options

1) Reduce amount of rice straw incorporation into rice soil, 1) Reduce amount of rice straw incorporation into rice soil,

2) conduct field drainage during growing period. 2) conduct field drainage during growing period. However, field drainage may induce weeds and possible to reduce rice However, field drainage may induce weeds and possible to reduce rice grain yield. Therefore, optimum drainage period in optimum growth stage grain yield. Therefore, optimum drainage period in optimum growth stage of rice plant needs to concern to obtain the practical mitigation option. of rice plant needs to concern to obtain the practical mitigation option.

3) Fertilizer application3) Fertilizer application

4. Rice cultivar 4. Rice cultivar

AcknowledgementsAcknowledgements

This research was funded by the grant of Eco-Frontier This research was funded by the grant of Eco-Frontier Fellowship program by Ministry of the Environment, Japan.Fellowship program by Ministry of the Environment, Japan.

We thanks Prof. C.S. Li for DNDC model. We thanks Prof. C.S. Li for DNDC model. Sincere thanks to Prof. Shu Fukai, Dr. Naruo Matsumoto, Sincere thanks to Prof. Shu Fukai, Dr. Naruo Matsumoto,

Dr. Niwat Nadheerong, Mr. Chitnucha Buddhaboon for Dr. Niwat Nadheerong, Mr. Chitnucha Buddhaboon for valuable data and their kindly suggestions on of Thai rice valuable data and their kindly suggestions on of Thai rice plants characteristics. plants characteristics.