Factors influencing CHFactors influencing CH44 and N and N22O O emissions emissions

from Asian croplands and potential mitigation from Asian croplands and potential mitigation optionsoptions

Xiaoyuan YanXiaoyuan YanFrontier Research Center for Global Change,Frontier Research Center for Global Change, Japan Japan

Hiroko Akiyama, Kazuyuki YagiHiroko Akiyama, Kazuyuki YagiNational Institute for Agro-environmental Sciences, JapanNational Institute for Agro-environmental Sciences, Japan

yanxy@jamstec.go.jpyanxy@jamstec.go.jp

0

10

20

30

40

50

60

70

80

90

100

Population Land area Rice Nitrogenfertilizer

% o

f w

orl

d t

ota

lCharacteristics of agriculture in the study regionCharacteristics of agriculture in the study region

CHCH44 emission from rice fields emission from rice fieldsMeasurement sites of CHMeasurement sites of CH44 emission from paddy emission from paddy

fields in Asiafields in Asia

Statistical analysis: A linear mixed modelStatistical analysis: A linear mixed model

)1ln(

)ln()(

AOMOMClimateWaterPW

pHOCaInterceptfluxLn

lkji

m

Fixed effects:Fixed effects: soil properties (SOC, pH)soil properties (SOC, pH) climateclimate water status before rice seasonwater status before rice season water regime during rice seasonwater regime during rice season type and amount of organic fertilizertype and amount of organic fertilizer

Random effect:Random effect: paperpaper

A statistical analysis of factors influencing CHA statistical analysis of factors influencing CH44 emission emission

EffectEffect Numerator Numerator DFDF Denominator Denominator DFDF FF value value Pr > Pr > FF††

SSOCOC 11 17841784 47.9547.95 <.0001<.0001

ppHH 77 17841784 91.4291.42 <.0001<.0001

PrePre-season water-season water 44 17841784 89.5589.55 <.0001<.0001

WWaterater regime regime 55 17841784 104.74104.74 <.0001<.0001

Organic amendmentOrganic amendment 55 17841784 116.48116.48 <.0001<.0001

CClimatelimate 66 17841784 32.4632.46 <.0001<.0001

Effects of SOC on CHEffects of SOC on CH44 flux flux

0 1 2 3 4 5 60.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

Re

lativ

e C

H4

flux

Soil organic carbon, %

0 1 2 3 4 5 60.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

Re

lativ

e C

H4

flux

Soil organic carbon, %

99% confidence

Effects of soil pHEffects of soil pH

<4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 >=8.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Re

lativ

e e

ffect

on

flu

x

soil pH

<4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 >=8.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Re

lativ

e e

ffect

on

flu

x

soil pH

99% confidence interval

0

0.5

1

1.5

2

2.5

3

3.5

0 5 10 15 20 25 30 35 40 45 50

Apprication rate of organic materials, t/ha

Rel

ativ

e C

H4

flu

x

Straw_on_season

Compost

Straw_off_season

FYM

GM

Response of CHResponse of CH44 emission to difference organic amendment emission to difference organic amendment

Rice-season Rice-season water regimes affects CH4 emissionwater regimes affects CH4 emission

0.360.360.180.180.250.25Rainfed, dry seasonRainfed, dry season

0.370.370.210.210.280.28Rainfed, wet seasonRainfed, wet season

0.800.800.460.460.600.60Single drainageSingle drainage

0.660.660.410.410.520.52Multiple drainageMultiple drainage

11Continuously floodedContinuously flooded

upperupperlowerlower

95% confidence interval95% confidence interval

Relative fluxRelative fluxWater regime in rice seasonWater regime in rice season

0.100.100.040.040.060.06Two drainagesTwo drainages

0.600.600.460.460.530.53Short drainageShort drainage

0.420.420.300.300.360.36Long drainageLong drainage

11FloodedFlooded

upperupperlowerlower

95% confidence interval95% confidence interval

Relative fluxRelative fluxPre-season water Pre-season water statusstatus

Off-season water status affects CHOff-season water status affects CH44 emission during rice emission during rice

seasonseason

Type III Tests of Fixed EffectsSource Numerator dfDenominator dfF Sig.Intercept 1 167 3.9401 0.0488Crop 5 167 3.3969 0.0060N-type 5 167 4.6961 0.0005N-amount 1 167 22.0315 0.0000Mitigation 2 167 2.5126 0.0841SOC 1 167 4.3411 0.0387pH 1 167 1.3213 0.2520TSN 1 167 0.0114 0.9149

Fixed effects:Fixed effects: soil propertiessoil properties crop typecrop type chemical N type and amountchemical N type and amount mmitigation optionitigation option

Random effect:Random effect: paperpaper

Field measurement data of N2O from croplands in Asian: Field measurement data of N2O from croplands in Asian: A Statistical analysis A Statistical analysis

A conceptional N cycle modelA conceptional N cycle model

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00

100

200

300

Fre

quen

cy

N2O emission, kg N/ha

200 kg N/ha, 5 rainfall events 150 kg N/ha, 5 rainfall events

0.0 0.5 1.0 1.5 2.00

50

100

150

200

250

300

Fre

nque

ncy

N2O emission, kg N/ha

200 kg N/ha, 5 rainfall events

0.0 0.5 1.0 1.5 2.00

50

100

150

200

250

Fre

nque

ncy

N2O emission, kg N/ha

150 kg N/ha, 5 rainfall events

Uncertainty caused by timing of rainfall eventUncertainty caused by timing of rainfall event

A Monte Carlo simulation: An upland field, fertilizedA Monte Carlo simulation: An upland field, fertilized with 200/150 kg N/hawith 200/150 kg N/ha

1000 runs, assuming1000 runs, assuming 5 rainfall events in a season5 rainfall events in a season randomly distributed in a season randomly distributed in a season Ratio of NRatio of N22O as a product of nitrification and O as a product of nitrification and

denitrifcation 20 times higher on raining days than denitrifcation 20 times higher on raining days than usualusual

Relatively well tested mitigation optionsRelatively well tested mitigation options

Nitrification Nitrification inhibitorinhibitor

Slow release fertilizerSlow release fertilizer

UplandUpland 0.72 (n=14)0.72 (n=14) 0.88 (n=13)0.88 (n=13)

PaddyPaddy 0.73 (n=9)0.73 (n=9) 1.08 (n=3)1.08 (n=3)

0 20 40 60 80 100 120-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

kg N

/ha/

day

Days after planting

N2O Urea

0 20 40 60 80 100 120-5

0

5

10

15

20

25

30

35

40

45

50

kg N

/ha

Days after planting

NH4 Urea

0 20 40 60 80 100 120

0

10

20

30

40

50

kg N

/ha

Days after planting

NO3 Urea

N dynamic in a upland fieldN dynamic in a upland field

0 20 40 60 80 100 120-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

kg N

/ha/

day

Days after planting

N2O Urea SRF

0 20 40 60 80 100 120-5

0

5

10

15

20

25

30

35

40

kg N

/ha

Days after planting

NH4 Urea SRF

0 20 40 60 80 100 120

0

10

20

30

40

50

kg N

/ha

Days after planting

NO3 Urea SRF

N dynamic in a upland fieldN dynamic in a upland field

0 20 40 60 80 100 120-5

0

5

10

15

20

25

30

35

40

45

50

kg N

/ha

Days after planting

NH4 Urea SRF Inhibitor

0 20 40 60 80 100 120

0

10

20

30

40

50

kg N

/ha

Days after planting

NO3 Urea SRF NO3

0 20 40 60 80 100 120-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

kg N

/ha/

day

Days after planting

N2O Urea SRF Inhibitor

N dynamic in a upland fieldN dynamic in a upland field

Urea: 1

SRF: 0.90

Inhibitor: 0.74

0 20 40 60 80 100-0.005

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

kg N

/ha

/da

y

Days after planting

urea srf inhibitor

Urea: 1Urea: 1

SRF: 1.7SRF: 1.7

Inhibitor: 0.98Inhibitor: 0.98

Modeled effects of slow release urea nitrification inhibitor Modeled effects of slow release urea nitrification inhibitor on Non N22O emission from paddy with O emission from paddy with

middle season and end season drainagemiddle season and end season drainage

Nitrification Nitrification inhibitorinhibitor

Slow release Slow release fertilizerfertilizer

UplandUpland 0.72 (n=14)0.72 (n=14) 0.88 (n=13)0.88 (n=13)

PaddyPaddy 0.73 (n=9)0.73 (n=9) 1.08 (n=3)1.08 (n=3)

ConclusionsConclusions

Management practices are more influential than climate and soil Management practices are more influential than climate and soil properties on CHproperties on CH44 emission from rice field emission from rice field. .

CHCH44 emission can be reduced by appropriate water management emission can be reduced by appropriate water management and use of organic materialsand use of organic materials

NN22O emission from paddy and NOO emission from paddy and NO33, COM tend to be smaller, COM tend to be smaller

Effects of soil properties, fertilizer and crop type on NEffects of soil properties, fertilizer and crop type on N22O emission O emission can be easily overshadowed by effect of rainfall-induced soil can be easily overshadowed by effect of rainfall-induced soil moisture changemoisture change

Nitrification inhibitors are effective to reduce NNitrification inhibitors are effective to reduce N22O emission from O emission from upland, slow release fertilizers are less effective; their effects on upland, slow release fertilizers are less effective; their effects on paddy depend on water regimepaddy depend on water regime