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

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

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

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

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

LU areas and SOC derived from overlaying LPIS, NSDB and ISM

LPIS Map

ISM

Data Acquisition1 km Buffer on Irish National Grid: SOC under a LC contains a Indicative Soil Type (IST) >50% area

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)

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)

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 <0.001

<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).

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 <0.001

<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).

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 0.69/0.75/0.79No 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 0.78/0.84Reduced tillage 0.05 Medium 0.34 0.85/0.92

High 0.33 0.94/1.02High +manure 0.10 1.22/1.32

Grazing Ppn (A)

Ppn (A)

Mineral & Organo-mineral

0.91 Mineral 0.76 Pasture 0.56Organo-mineral

0.24 Hay 0.06

Organic 0.09 Silage 0.26Rough grazing 0.12

Management Inputs Ppn (A) EFs (G/R)Mineral & Organo-mineral

Non-degraded Low 0.38 1.00/1.00Improved Medium 0.40 1.14/1.14

High 0.22 1.27Organic Degraded Low 0.08 0.95/0.95

Non-degraded Medium 0.30 1.00/0.95Improved High 0.40 1.14/1.14

0.22 1.27

Proportion of area under management and inputs across LUS and the IPCC EFs

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

Proportion of land use change between 1990 and 2014

Source: EPA, CSO and Our works

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?

(Source: CGIAR, 2011)

THANK YOU

AcknowledgementsIrish Environmental Protection Agency (EPA) for funding

Phillip O’Brien, EPA for providing relevant data

John Muldowney, DAFM for input