Yasuhito SHIRATO(NIAES, Japan)

Soil Carbon Sequestration and Greenhouse Gas mitigation in 

Agriculture

MARCO: 26 August, 2015

Contents

1. Mitigation of climate change2. Soil C sequestration3. CH4 and N2O4. Collaboration in Asia

IPCC AR５ Chapter 11 AFOLU p811, SPM.4.2.4 p24

Global anthropogenic GHG emissionsAFOLU (Agriculture, Forestry and other Land use)

Contribution of AFOLU is not small

Contribution of Asia in AFOLU emission

IPCC AR5 Chapter 11 AFOLU p820

Contribution of Asia is big

Global technical mitigation potential  IPCC AR4 (2007)

Soil C sequestration (CO2) has the biggest mitigation potential among 3 GHGs

Carbon is cycling

InputOutput

•In cropland, C in “biomass” does not change in longer time‐scale. Increase in SOC means decrease in atmospheric CO2. Option for increasing SOC: Increase C input or decrease decomposition rate.

• Basically soil productivity and C sequestration is win‐win • Soil productivity is first, C sequestration is second. 

Mitigation options for Soil C: Organic matter application

Long‐term experiment (Gray Lowland Soil; upland)

化 学 肥 料 単 用 区

稲 わ ら た い 肥 0 .2 5 t 区

稲 わ ら た い 肥 0 .7 5 t 区

0.5

1

1 .5

2

2 .5

1 2 3 4 5 6 7 8 9 10 11 12 13 1 4 15 16 17 18

（連 用年数）

（全炭 素(% )）Total C (%)

Years

Plot with Chemical Fertilizer Only

Plot with Rice Straw Compost (2.5t/ha/year)

Plot with Rice Straw Compost (7.5t/ha/year)

Data：”Basic Survey of Soil Environment (Benchmark Survey)” Yamaguchi Pref. Agricultural Research Institute

*Figure for a year is the three‐year average including the previous and the next year to that year.

Increasing C inputsCompost application

OM application: Green manure

Lal (2004)Mucuna (leguminous） Increasing C inputs

No‐tillage

（Kanazawa, 1995）

•Reduce OM decomposition•More successful  in the U.S. etc.•Not widely spread in Japan (may be in Asia, too) •Weed problem is severe in humid Asia 

TillNo-till

Total C (%)

Dep

th (c

m)

Decreasing C outputs

No‐till and residue mulch

Lal (2004)

Increase C input & decrease C output

Biochar

(Yanagita, 1997)

Charred cattle dung

Charred rice husk

WeeksCO

2 em

issi

on

Non‐charredHalf‐charredCharred material

• Very slow decomposition• Co‐benefits (crop growth, reduce N2O, absorb toxic chemicals etc.)• Lots of experience in Japan, but not systematically studied• Quality varies (material, temperature etc.)

Modelling soil C

Soil C models are useful tools. Future projection Spatial evaluation (e.g. country scale estimation of soil C sequestration potential)

Question: how to and how much can we sequester C in soil by changing agriculture practices ?

Soil C: RothC (Rothamsted carbon) model

• Validation using long‐term experimental datasets

• Modified the model for paddy soils and for Andosols (volcanic ash‐derived soils)

Inputs: weather, soil, management

Outputs: SOCMonthly step

Paddy

Upland (Other soils)

Upland (Andosols)

Paddy soils

Validation and modification of the RothC

Andosols

Anaerobic conditionSlow decomposition

Stable humus with active AlSlow decomposition of “HUM” pool

Modified model Original RothC: successful Modified model

Country scale simulation using 3 versions: National Inventory Report (NIR) 2015 

Anjyo: NPK+FYMb

0

10

20

30

40

50

60

1975 1976 1977 1978 1979 1980 1981

SO

C (t

C h

a-1 )

Fujisaka: NPK+FYM0

20

40

60

80

1935 1955 1975 1995

SO

C (

t ha-

1)

Original

Modified

Measured

0

5

10

15

20

25

30

35

40

1976 1981 1986 1991

SO

C (t

ha

-1)

NPK observedNPK+straw observed

NPK modified modelNPK+straw modified model

Toyama

Arable soils: ~500 million ha

(Shirato & Yokozawa, 2005)(Shirato & Taniyama, 2003)(Shirato et al., 2004)

CH4

• Submerged soil in paddy field during rice growing season

• Water management (e.g. drainage)• Organic matter management (e.g. straw management)

0

10

20

30

40

CH

4flux

（m

g m

-2

hr-

1）

MAY JUN JUL AUG SEP

14 days 21 days

7 days drainage

aeration

Extending Mid‐Season drainage

Continuous flooding

湛水期間Flooding

50 kg N/ha

30 kg N/ha

CH4: Mitigation option

0

20

40

60

80

処理1 処理2 処理3 常時湛水

メタ

ン発

生量

(gCH4m

-2)

21 days drainage

Seasonal CH4 Emissions

14 days drainage

7 days drainage

Continuous flooding

Decrease in rice yield

81% 61%

Conventional practice

51%

Fukushima, Japan

Decom-position

DOC

H2

OxidationMethanogenesisReduction

CO2

CH4O2

Photosynthesis, C allocation

Litter fall Transport

Fe3+, Mn4+

Fe2+, Mn2+

CH4

Transport

Diffusion

CO2

N & water uptake

NH4+

CO2

Nitrifi.Denitrifi.

NO3-

NH3, N2, N2O, NO O2

DNDC‐Rice modelModified version of DNDC for paddy rice field

CH4: modelling

18

0

100

200

300

400

0 100 200 300 400

Sim

ula

ted C

H4

em

issi

on (

kg C

ha

-1)

Observed CH4 emissison (kg C ha-1)

Pippu

Shizukuishi

Koriyama

NIAES

Ryugasaki

Nanjing

r = 0.90Mean error = ‐0.5kg C ha‐1RMSE = 35.1 kg C ha‐1

Tested treatments: residue incorporation (Pippu, NIAES), water regime (Pippu, Koriyama, Ryugasaki), CO2concentration (Shizukuishi), sulfate application (Nanjing) (Fumoto et al., 2008; 2010; 2013)

Emission factor derived from DNDC‐Rice modelling used in NIR from 2015

CH4: modellingObservation VS. DNDC‐Rice model:

Seasonal methane emission 

N2O

Source: N in fertilizer and organic matter  Mitigation options: reduce N application rate (increase N use efficiency)

Changing fertilizer (e.g. Nitrification inhibitor, coating fertilizer) 

Nitrification inhibitor for reducing N2O emission

0

10

20

30

40

6/11

6/21

7/1

7/11

7/21

7/31

8/10

8/20

8/30

9/9

9/19

9/29

10/9

10/19

D ate (月/日)

N2O Flux (μg N m-2 h-1)

被覆肥料区

硝化抑制剤区

通常肥料区

追肥基肥

N 2O

播種収穫

0

5

10

15

20

25

N2O

発生

量（m

g N

/m

2）

被覆肥料区

Data from a carrot field on Andosol （Akiyama et al., 2000）

N2O: Mitigation option

Coating fertilizerNitrification inhibitorConventional

Coating fertilizer

Nitrification inhibitor

Conventional

N N Harvest

Sawing

N2O

 emission

N2O emission = A exp[B*(ECO2/SCN+Fn)]

Decomposed‐CO2:

C:N of organic matter

Chemical 

fertilizer N

96 data from USA (4 sites), German (4 sites) and Canada (1 site); 14 data from Japan (2 sites); 4 data from China (1 site)

RothC

Combination of the RothC and empirical N2O modelMineralized N from OM

N2O: modelling

Mu et al. (2009)

Evaluating total GWP at country scale 

Increase C inputs

CH4 and N2O increase

SOC increaseRothC

RothC+N2O modelDNDC‐Rice

• Evaluating total GHGs (GWP) considering “Trade‐ off” by using three different models

• Country scale evaluation  with tier 3 method.

Decision‐support tool on the webhttp://soilco2.dc.affrc.go.jp/

1. Click on the map  weather, soil2. Choose crop set residue & manure management (Default values available) 3. Calculate SOC easily4. Calculate CH4, N2O and CO2 derived from fossil fuel, too.

Synergy with adaptation Agriculture has been already affected by

climate change: adaptation is becoming important

Option only for mitigation is not accepted Synergy of mitigation and adaptation Soil C sequestration for mitigation and

improving soil productivity: win-win

Soil CSoil qualityProductivity

Climate change mitigation

Collaboration with Asian countries

Japan is small. Mitigation potential in Asia is big. Similar agro‐environmental conditions Collaboration with Asian countries both in GHG 

monitoring and modelling

e.g. MIRSA (Mitigation in Irrigated Rice Paddies in Southeast Asia) project: paddy water management: AWD (Alternate Wetting and Drying) in four Asian countries

RothC and/or DNDC‐Rice model application (e.g. China, Thailand, Vietnam) 

25

A research project funded by MAFF, Japan, from 2013 to 2018 Aiming at assessing the feasibility of GHG mitigation through water

saving techniques (AWD) in irrigated rice fields Results shows effectiveness of AWD to reduce CH4+N2O emissions

MIRSA Project(Greenhouse Gas Mitigation in Irrigated Rice Paddies in Southeast Asia)

2013‐14 Dry season, Pati, Indonesia

Unpublished data

1 2

3

Testing the RothC  in Thailand

Khon Kaen (27 years, Cassava)

Phraphuttabat (28 years, Corn)

Nakon Ratchasima (28 years, Cassava)

Khon Kaen: NPK

0

5

10

15

1976 1981 1986 1991 1996 2001

Phraphuttabat: NPK0

5

10

15

20

1976 1981 1986 1991 1996 2001

Nakon Ratchasima: NPK

0

5

10

15

20

1975 1980 1985 1990 1995 2000

Validation of the RothC in ThailandSO

C (t

ha-

1 )

Generally good agreementfor long‐term (27‐28 yrs) SOC change

NPK plotsNil plots(without OM application)

Shirato et al. European J. Soil Sci.(2005)

Summary

Contribution of AFOLU sector is not small Mechanisms studies progressed, and mitigation

strategies understood for SOC, CH4 and N2O Developed models. Web-based decision support

tools developed Country scale simulation with some mitigation

scenarios to evaluate total GWP (LCA) Co-benefits, synergy with adaptation needed Collaboration in Asia is becoming important

Thank you for your attention !