This presentation was presented during the 3 Parallel session on Theme 1, Monitoring, mapping, measuring, reporting and verification (MRV) of SOC, of the Global Symposium on Soil Organic Carbon that took place in Rome 21-23 March 2017. The presentation was made by Mr. Ibrahim Khalil, from UCD Earth Institute/ University College – Ireland, in FAO Hq, Rome

1. Type relevant Irish
language Unit Name into
this text box in Title Master.
Type relevant English
language Unit Name into
this text box in Title Master.
Coupling High Spatial Resolution
Data, GIS Approaches and Modelling
for Reliable Estimates of SOC stocks
and Their Historical Changes in
Agricultural Land
UCD School of Biology and Environmental Science
and UCD Earth Institute, University College Dublin,
Belfield, Dublin 4, Ireland
M. I. Khalil and B. A. Osborne
GLOBAL SYMPOSIUM ON SOIL ORGANIC CARBON,
FAO HQ, ROME, ITALY, 21-23 MARCH 2017

2. Contamination of waterbodies
More
Inputs
More
leaching
More
GHGs
Trade-
off/Offset:
SOC
Soil Organic Matter
• Soil Quality/Health: Fertility and Productivity
• Adsorbent of environmental toxicants
• Storehouse of atmospheric CO2: Sequestration
• Source of Greenhouse Gases: CO2, CH4 and N2O

3.  Ireland: Annex-I country – obligation for accounting and
reporting to UNFCCC: AG + LULUCF = AFOLU
 Article 3.3: Aforestration, deforestration and
reforestration
 Article 3.4: Agricultural soils but also to cover soil C
dynamics
 Paris agreement: Climate change: temp. rise<2oC
 Carbon credits benefits, trade-off relations and offsetting
International Agreements

4. Uncertainty: Sources
of variation & error
Sampling error
• Topography
• Land use and management
• Number of samplings
• Consistency in sampling time
Preparation error
• Compositing
• Homogenization
• Grinding, screening, sifting, storage
Analytical error
• QA/QC: Standard methods
(Org + Inorgorganic = Total)
Principal structure and soil
profile sampling scheme
SOC accounting: IPCC default Tier 1 to
country-specific Tier 2 mainly

5. Developed methodologies and
models to estimate baseline
SOC concentrations, densities
and stocks (0-10, 0-30 & 0-
100 cm depth) for 2006.
Compiled and analysed databases to identify
agricultural land uses, their changes and
management practices.
Compiled databases for common
agricultural land uses, management
practices and inputs.
Estimated reference SOC (SOCref) for 1990 through
back calculation and historical changes in SOC
stocks (2006-2014) across key agricultural LULUC.
Overlaid LPIS (2000-
2014) on NSDB and ISTs
using Arc-GIS.
Compiled research and country-
specific IPCC emission factors
(EFs) for management practices
and inputs in relation to SOC
sequestration/loss.
STEPS: Soil Carbon Accounting

6. LU areas and SOC derived from overlaying
LPIS, NSDB and ISM
LPIS
Map
ISM

7. Data Acquisition
1 km Buffer on Irish National Grid: SOC under a LC contains a
Indicative Soil Type (IST) >50% area

8. Common Soil
type
Level of
degradation
Major land
covers
Acidity Drainage
classes
Indicative soil types Depth distribution
models x SOCz10 *
R2 CV
%
Mineral soil
(SOC<10%)
Non-degraded Grassland Non-
Calcareous
Well AminDW, AminSW y = 1.4002e-0.035x 1.0000 30
Poorly AminPD (+AminSP) y = 1.3661e-0.034x 0.9998 31
Calcareous Well BminDW, BminSW y = 1.3719e-0.035x 0.9999 33
Poorly BminPD y = 1.3654e-0.034x 0.9998 26
Tillage Non-
Calcareous
Well AminDW, AminSW y = 1.5647e-0.029x 0.9947 29
Poorly AminPD y = 1.5195e-0.026x 0.9928 34
Calcareous Well BminDW, BminSW y = 1.5328e-0.03x 0.9966 63
Poorly BminPD y = 1.5055e-0.025x 0.9920 17
1. Depth distribution models for the estimation of SOC across soil depths
for IST and key agricultural land covers in Ireland (Khalil et al., 2013)

9. Common Soil
type
Level of
degradation
Major land
covers
Acidity Drainage
classes
Indicative soil types Depth
distribution
models x SOCz10
*
R2 CV
%
Organo-mineral
soil (SOC 10-
20% and >20%
at <30cm depth)
Non-degraded
(SOC >20% at
<30cm depth)
Rough
grazing,
Grassland,
Tillage
Non-
Calcareous
Mixed, Poorly
major
AminSRPT,(AminPDPT,AlluvMIN
, AminPD, AminDW, AminSW)**
y = 1.5652e-0.042x 0.9999 09
Calcareous Mixed, well
major
BminPDPT (BminDW, BminPD,
BminSW)**
y = 1.6084e-0.041x 0.9996 10
Degraded
(SOC 10-20%
at <30cm
depth)
Grassland,
Rough
grazing,
Tillage
Non-
Calcareous
Mixed, Poorly
major
AminPDPT, AminSRPT,(AminPD,
AminDW)** AlluvMIN?); If
SOC10cm: 10-20% (y1)/<10% (y2)
y1 = 2.3718e-0.038x 0.9703 27
y2 = 3.5709e-0.035x 0.8843 27
Calcareous Well BminPDPT, BminSRPT,
(BminDW, BminSW)** If
SOC10cm: 10-20% (y1)/<10% (y2)
y1 = 2.7101e-0.037x 0.9485 10
y2 = 4.9308e-0.031x 0.7630 12
Organic soil
(SOC >20% and
10-20% at
>30cm depth
Non-degraded
(SOC >20% at
>30cm depth)
Rough
grazing,
Grassland,
Tillage***
Non-
Calcareous
Undefined Cut y = -0.164ln(x)+
1.4431
0.9217 38
Undefined BkPt y = -0.066ln(x)+
1.2306
0.5798 13
Degraded
(SOC 10-20%
at >30cm
depth)
Rough
grazing,
Grassland,
Tillage
Non-
Calcareous
Undefined Cut = if SOC10cm: 10-20% y = 0.2692ln(x)+
0.3866
0.5347 35
Undefined BkPt = if SOC10cm: 10-20% y = 0.4357ln(x)-
0.0383
0.6080 12
Undefined Cut = if SOC10cm: <10% y = 1.1682ln(x)-
1.0111
0.6838 36
Undefined BkPt = if SOC10cm: <10% y = 1.3518ln(x)-
1.6659
0.7232 13
2. Depth distribution models for the estimation of SOC across soil depths
for IST and key agricultural land covers in Ireland (Khalil et al., 2013)

10. Common Soil
type
Level of
degradation
Major land
covers
Acidity Drainage
classes
Indicative soil
types
y = PTF, x = SOCz * R2 SSE MSE RMSE
Organo-
mineral soil
(SOC 10-20%
and >20% at
<30cm depth)
Non-degraded
(SOC >20% at
<30cm depth)
Rough
grazing,
Grassland
Non-
Calcareous
Mixed,
Poorly
major
AminSRPT,
(AminPDPT,
AlluvMIN, AminDW,
SW, PD,)**
y = 0.2170+1.0763e-0.080x 0.76 2.043 0.028 0.166
Rough
grazing,
Grassland
Calcareous Mixed, well
major
BminPDPT,SRPT
BminDW, SW,)**
y = 0.1067+1.4473e-0.072x 0.99 <0.00
1
<0.001 0.003
Degraded
(SOC 10-20%
at <30cm
depth)
Grassland,
Rough
grazing
Non-
Calcareous
Mixed,
Poorly
major
AminPDPT, SRPT,
(AminDW, SW,PD,
AlluvMIN,)**
y = 0.2012+1.1592e-0.081x 0.67 8.037 0.028 0.166
Grassland Calcareous Well BminPDPT, SRPT
(BminDW, SW)**
y = 0.3749+0.9901e-0.119x 0.89 1.191 0.005 0.071
Organic soil
(SOC >20%
and 10-20%
at >30cm
depth
Non-degraded
(SOC>20% at
>30cm depth)
Rough
grazing,
Grassland
Tillage***
Non-
Calcareous
Undefined Cut y = 0.1235+2.5048e-0.085x 0.75 0.190 0.003 0.053
Tillage***
Rough
grazing,
Grassland
Undefined BkPt y = 0.1437+5.7679e-0.121x 0.83 0.251 0.002 0.048
Degraded
(SOC 10-20%
>30cm depth)
Rough
grazing
Grassland
Non-
Calcareous
Undefined Cut y = -0.0751+1.5674e-0.042x 0.91 0.293 0.011 0.104
Rough
grazing
Grassland
Undefined BkPt y = -0.2125+1.7592e-0.031x 0.87 0.341 0.014 0.119
2. Pedo-transfer functions for soil bulk density estimation across depths
for IST and key agricultural land covers in Ireland (Khalil et al., 2013).

11. Common Soil
type
Level of
degradation
Major land
covers
Acidity Drainage
classes
Indicative soil
types
y = PTF, x = SOCz * R2 SSE MSE RMSE
Mineral soil
(SOC<10%)
Non-degraded Grassland Non-
Calcareous
Well AminDW, AminSW y = 0.7468+0.6559e-0.260x 0.70 9.290 0.011 0.105
Poorly AminPD(+AminSP) y = 0.2882+1.1420e-0.106x 0.90 1.644 0.003 0.056
Calcareous Well BminDW, BminSW y = 0.5041+0.8982e-0.146x 0.92 1.487 0.002 0.047
Poorly BminPD y = -0.0275+1.4995e-0.083x 0.99 0.001 <0.001 0.003
Tillage Non-
Calcareous
Well AminDW, AminSW y = 0.4827+0.9227e-0.153x 0.80 0.091 0.002 0.049
Poorly AminPD y = 0.9302+0.6003e-0.209x 0.99 0.004 <0.001 0.010
Calcareous Well BminDW, BminSW y = -0.0154+1.6219e-0.125x 0.99 0.001 <0.001 0.003
Poorly BminPD y =-0.0977+1.6157e-0.063x 0.99 <0.00
1
<0.001 0.003
1. Pedo-transfer functions for soil bulk density estimation across depths
for IST and key agricultural land covers in Ireland (Khalil et al., 2013).

12. Proportion of area under management and
inputs across LUS and the IPCC EFs
Tillage/
Arable
Management Ppn
(A)
Inputs Ppn
(A)
EFs
Mineral
soil only
Full tillage 0.80 Low 0.23 0.63/0.69/0.73
Reduced tillage 0.15 Medium 0.34 0.69/0.75/0.79
No tillage 0.05 High 0.33 0.77/0.83/0.88
High +manure 0.10 0.99/1.07/1.14
Temp
grass
Management Ppn
(A)
Inputs Ppn
(A)
EFs
Mineral
(0.86)
& Organo-
mineral
(0.14) soil
Full tillage 0.95 Low 0.23 0.78/0.84
Reduced tillage 0.05 Medium 0.34 0.85/0.92
High 0.33 0.94/1.02
High +manure 0.10 1.22/1.32

13. Grazing Ppn
(A)
Ppn (A)
Mineral &
Organo-
mineral
0.91 Mineral 0.76 Pasture 0.56
Organo-
mineral
0.24 Hay 0.06
Organic 0.09 Silage 0.26
Rough grazing 0.12
Management Inputs Ppn (A) EFs (G/R)
Mineral &
Organo-mineral
Non-degraded Low 0.38 1.00/1.00
Improved Medium 0.40 1.14/1.14
High 0.22 1.27
Organic Degraded Low 0.08 0.95/0.95
Non-degraded Medium 0.30 1.00/0.95
Improved High 0.40 1.14/1.14
0.22 1.27
Proportion of area under management and
inputs across LUS and the IPCC EFs

14. SOC density for estimated (1990) and measured
(2006) values

16. Proportion of land use change between
1990 and 2014
Source: EPA, CSO and Our works

17. Conclusions
 Coupled GIS and modelling approach provides a robust estimate of
SOC concentration and density/stocks for Tier 2 development.
 IPCC approaches should be re-evaluated for more robust accounting
systems:
o that track the actual rate of stock change with management
o that correctly account for agricultural management activities.
 Based on the IPCC default EFs used, the SOC sources and sinks in
agricultural soils is balanced/neutral.
 Options to achieve a carbon neutral agricultural sector by 2050:
(i) Advanced GHG mitigation strategies: Technological limitation??
(ii) Carbon sequestration: Improved management and higher C in
agricultural soils: strategy for beyond 30 cm depth?
(iii) Afforestation (1.25 M ha) may raise concerns if this involves the
replacement of agricultural land – but use marginal lands?

18. (Source: CGIAR, 2011)
Acknowledgements
Irish Environmental Protection Agency (EPA) for funding
Phillip O’Brien, EPA for providing relevant data
John Muldowney, DAFM for input