Towards More Efficient Soil Towards More Efficient Soil Carbon Measurement and Carbon Measurement and
MonitoringMonitoring
Alex. McBratneyBudiman Minasny
Australian Centre for Precision AgricultureFaculty of Agriculture Food & Natural
Resources
Rationale
• Soil stores a lot of carbon• The win-win of storing carbon
Soil stores a lot of carbon 1
• Global organic C storage (0-1 m):
1,200 – 1,600 Petagrams
Soil carbonate carbon larger
0.01
0.1
1
10
100
C O
rg (
%)
-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70
Lat
Atmosphere 770
Vegetation 600
Oceans 40 000
Global NPP 57
Petagram = 1015g = 1012 kg = 109 tonnes
Soil stores a lot of carbon 2
• Globally NPP: 57 x 109 t C y-1
• Edgeroi (150 000 ha): Corg Storage (to 1m) : 13 x 106 t
C• IA Watson (427 ha)
Corg Storage (to 1m) : 25 x 103 t C
0 - 5
5 - 6
6 - 7
7 - 8
8 - 9
9 - 10
10 - 11
11 - 12
12 - 14
14 - 16
16 - 18
18 - 20
Carbon Storage (0-1 m) (kg m-2)
1 = kg m-2 = 10 tonnes/ha 0 10,000 20,0005,000 Meters
K
Z
Slope
Aspect
TWI
Land Use
H1
H2
H3
Ca
Cb
k
Input Hiddenlayer
Output
ˆ ˆ expa bC C k z C
z0
0.2
0.4
0.6
0.8
1
1.2
1.4
0.0 0.5 1.0 1.5 2.0 2.5
C (kg m-3)
Dep
th (m
)
CALCAROSOL
CHROMOSOL
DERMOSOL
KANDOSOL
RUDOSOL
SODOSOL
VERTOSOL
Rudosol
Vertosol
Dermosol
Calcarosol
Kandosol
Chromosol
Sodosol
0 - 5
5 - 6
6 - 7
7 - 8
8 - 9
9 - 10
10 - 11
11 - 12
12 - 14
14 - 16
16 - 18
18 - 20
C Storage Edgeroi
The win-win of storing carbon
• Results from StrucCStrucC – Malamoud, McBratney, Minasny & Field 2008
FOM input
Per month
TYPE 1
CO2
CO2
Clay content
SOCm
Clay mass
Complexed clay
NCOC
RPM CO2 CO2
NCOC = f(SOC,clay)
TYPE 2
TYPE 3
Initial bulk density
CC = f(SOC,clay)
DPM
CO2
Non-complexed clay
Is used to calculate
Goes to
Lost
CO2
Fresh matter / pools calculated in the same manner as RothC-26.3
Aggregated and non-aggregated carbon pools
Struc-C
The proposition
• A soil carbon accounting and trading scheme
A soil carbon accounting and trading scheme
Independent auditor Carbon Emitter
Landholder
Government
Buy C offsetCertified Carbon Emission Reduction
credits
Offsetting company
soil carbon sequestrationcontract
Carbon emission target
Audit soil Cat beginning and end of
sequestration contract
soil carbon audit reporting trail
soil C auditing TOOL
(Research)
Advisor of Land management system
Management to optimise C sequestration
Ongoing Land Management and Soil Research
reporting
reporting
e.g. C-Lock
The problem
• Soil carbon is difficult and relatively expensive to measure and monitor
• Two aspects
Cost of measuring soil C
• Soil sampling ~ $100/profile
• Each profile: 4 layers, total C measurement: $40
• Cost per profile: $140
0
1
2
3
4
5
6
0 10 20 30 40 50
No. samples
Std
. d
ev.
C e
stim
ates
Variation of soil carbon with depth and across space
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 10 20 30 40 50
C (kg m-3)
Dep
th (
m)
Changes over time
0.0
0.5
1.0
1.5
2.0
2.5
0 5 10 15 20 25 30
No. years cleared
To
tal C
(d
ag
kg
-1)
C = 0.7 exp(-0.13 years) + 0.8
Odeh et al. (2002)
And by the way …..
0.0
0.5
1.0
1.5
2.0
2.5
0 5 10 15 20 25 30
No. years in irrigated cultivation
Tot
al C
(da
g kg
-1)
SEQUESTRATION POTENTIAL
General trend of total soil C storage decline ~0.6 kg m-2 in 20 years
Over the whole area (427 ha) ~ 2700 ton C
4
56
78
910
1112
C S
tora
ge (
kg/m
2)
1985 2007Year
Changes over time
Solutions ……
• Cheaper measurement
• Defining the object
• Monitoring scheme
• Stochastic contracts
Cheaper measurement
• Lab and field NIR/MIR, LIBS, INS
• Cheaper but less precise
Cheaper measurement
• field NIR - profiler
• Cheaper but less precise
Cheaper measurement
• field NIR –
• on-the-go
• Faster, one depth Cheaper but less precise
Inelastic neutron scattering
Wielopolski et al., 2008 Nondestructive System for AnalyzingCarbon in the Soil.Soil Sci. Soc. Am. J. 72, 1269-1277
Defining the object
• What should the object be?
• Paddock, landuse etc.
• Need to measure C
1 2t tC C C
2 1
1
A
C z z dA
x
x x x
Monitoring scheme
• Scheme to measure C with minimised known uncertainty
1 1 22 1 2 2t t t t t tV C V C C V C V C V C V C
Monitoring scheme
• Too expensive?
• Something simpler required
• Need whole paddocks or properties
Source: Australian Natural Resources Atlas
http://www.anra.gov.au/topics/soils/monitoring/index.html
Nowley Liverpool Plains 2008
stratified random stratified random
sampling schemesampling scheme
1 Crop
2 Drainage
1 Remnant
2 Crop
1 Pasture
2 Pasture
3 Crop
3 Drainage
3 Pasture
4 Crop
4 Remnant
5 Pasture
4 Pasture
Sample location
N
6-1011-1516-2021-2526-3031-35
Total C kg/m3
N
STRATUM Total Carbon
(kg/m3)Stratu
m Area %
Stratum Area (ha)
Carbon (Mg =
tonne)
4 cropping 13.4 34.5 247 33105
1 pasture 14.9 3.0 7 1086
4 pasture 15.1 1.7 169 25614
2 cropping 15.2 1.3 175 26532
2 drainage 16.6 16.0 10 1679
3 cropping 18.3 9.9 534 97741
3 drainage 18.4 10.9 46 8503
3 pasture 19.9 0.7 46 9212
1 cropping 20.5 4.5 12 2439
4 remnant veg 22.8 0.5 20 4459
1 remnant veg 23.0 11.3 70 16088
2 pasture 26.0 0.8 153 39821
5 pasture 27.1 5.1 79 21346
Total C to 1 m = 287 627 tonnesTotal area of Nowley = 1570 ha
• STILL TOO EXPENSIVE!!?
Carbon calculators
Indicative
Not accurate
Suggestion “Moral hazard reduction”
contracts
• Inevitable uncertainty in C.
• Pay carbon sequesterer on, say, lower 95% confidence value
• But if producer wants higher payment then he can invest in more measurement to reduce C uncertainty.
Latest developments
• We have a 3-year Australian Research Council Linkage project to work on this – awarded Oct. 2008, begins Mar. 2009
• Partners USyd ACPA, EES and 3DAg.
Summary
Independent auditor Carbon Emitter
Landholder
Government
Buy C offsetCertified Carbon Emission Reduction
credits
Offsetting company
soil carbon sequestrationcontract
Carbon emission target
Audit soil Cat beginning and end of
sequestration contract
soil carbon audit reporting trail
soil C auditing TOOL
(Research)
Advisor of Land management system
Management to optimise C sequestration
Ongoing Land Management and Soil Research
reporting
reporting
e.g. C-Lock
Conclusion
Soil carbon auditing as part of carbon emissions offsets trading
• There’s a good reason to do it
• There are some obstacles
• We need to find solutions quickly but we’re on the way
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results
N
Total C kg/m3
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