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 !