Carbon Sequestration in European Agricultural Soils by 2010 -

Potential, Uncertainties, Policy Impacts

Annette FreibauerI.A. Janssens

Mark D. A. RounsevellPete Smith

Jan Verhagen

Outline1 Brief outline of CarboEurope

2 C balance of European biosphere

3 Potential for C sequestration and associated uncertainties

4 Environmental side effects, other greenhouse gases

5 Technical and economic barriers - feasibility

6 Putting C sequestration in climate perspective

7 From science to policy: ECCP, ETAP

CarboEurope

• The problem• The aim• The people• The way we work• Some results • The future

www.bgc-jena.mpg.de/pub/carboeur/

Who is CarboEurope?

Israel 1Norway 1

Poland 1Austria 2

Ireland 2 Spain 2Switzerland 2

Belgium 3Hungary 4

Czech Rep. 5

Denmark 5

Finland 5

Sweden 7

Netherlands 12France 13UK 16

Italy 17

Germany 20

Russia 4

Portugal 2

Total number of senior scientists: 124

Funded and coordinated by the European Commission DG XII Research

µmdm

ha

10 km

1000 km

Downscaling

Verification

Upscaling

Prediction

The way CarboEurope works

A: inclusion of uncertainty in fossil fuel emissionsB: correcting atm. signal for C losses in Non-CO2 gaseous compoundsC: correcting atm. Signal for CO2 release bypassing the ecosystem stocks (internat. trade)D: correcting land-based signal for C accumulation in wood products pool

Europe, Biospheric C Balance

Janssens et al., 2003, Science 300(5625): 1538-1542

Ecosystem Area (Mha) NBP (Tg C/a)

Forest, wooded land 389 (27) 377 (159) sink

Croplands 326 (32) -300 (186) sourceGrasslands 151 (36) 101 (133) sink?Subtotal -199 (229) source?

Undisturbed peatland 39 (6) 13 (7) sinkDrained peatlands 16 (4) -30 (15) sourcePeat extraction -50 (10) source

TOTAL 111 (279)

Europe, Ecosystem C Balance

Janssens et al., 2003, Science 300(5625): 1538-1542

High estimate

Low estimate

a

b

c

d

e

f

Simulated carbon fluxes in soil organic matter in Europe (tC ha-1 y-1) in the commitment period 2008-2012 (business-as-usual scenario);

(a – c) arable fields, (d – f) grassland.

Simulations were made using the mean soil organic carbon content reported by as the initial situation in 2000 (b and e), mean organic carbon content minus standard deviation (a and d), and mean organic carbon content plus standard deviation (c and f).

Vleeshouwers & Verhagen, GCB 8: 519 (2002)

Carbon fluxes in SOC in Europe (tC ha-1 y-1) in the 1st commitment period

Country C flux (t C/ha/a) Reason

Austria, crop -0.17 Changes in crop rotationBelgium, crop -0.90 Changes in management

reduced intensityFinland, crop -0.09 Peat oxidation,

discounted over entire areaUK, crop -0.56 Grass to crop conversion,

set-aside

Germany, grass >0.2 Crop to grass conversionin 1960s

C loss under crops, C uptake under grass

General Constraints

SCALE

Where is the economic optimum of C stocks in agricultural soils?

NON-PERMANENCE

C sequestration is immediately reversed to a source if sequestration measures cease (e.g. no-till)

European Specifics

C sequestration potential in agricultural soils is highest in - highly degraded soils and- relatively dry-continental conditionsBoth situations are not typical for Europe

European soils are less easily degradable than e.g., the great plain soils

European climate is more humid than e.g. the great plains

European soils and agricultural management have a high small-scale diversity, which complicates any generalisation(e.g. farm sizes in hilly regions < 50 ha land)

Potential measures for cropland-2 -1 0 1 2 3 4 5 6 7

Zero-tillage

Reduced-tillage

Set-aside

Grasses and permanent crops

Deep-rooting crops

Animal manure

Crop residues

Sewage sludge

Composting

Improved rotations

Fertilisation

Irrigation

Bioenergy crops

Extensification

Organic farming

t C/ha/yDepends on applied amount of organic matter per hectare. Larger scale: effect levels out.

Trend: less manure

Potential measures for grassland

-2 -1 0 1 2 3 4 5 6 7

Increase the duration ofgrass leys

Change from short durationto permanent grasslands

Increase of fertilizer onnutrient poor permanent

grassland

Intensification of organicsoils with permanent

grassland

t C/ha/y

From Soussana, pers. comm.

Potential measures for peatlands0 1 2 3 4 5 6 7

Protection and restoration

Avoid row crops and tubers

Avoid deep ploughing

More shallow water table

Convert arable to grassland

Convert arable to woodland

New crops on restoredwetlands from arable

New crops on restoredwetlands from grassland

Sheep grazing onundrained peatland

Abandon for conservation

t C/ha/y

Potential measures for land conversion

-2 -1 0 1 2 3 4 5 6 7

Convert arable towoodland

Convert arable tograssland

Convert grassland toarable

Convert permanent cropsto arable

t C/ha/y

Factors limiting carbon sequestration

Sink saturation

Non-permanence

Availability of land and resources

Adoption of measures

Limitations by soil properties

ECCP, Working Group Sinks Related to Agricultural Soils, Final Report , 2002.

Suitability for spreading of sewage sludge

Susceptibility to soil compaction

Availability of land and resources / potentialSoil carbon sequestration (Mt CO2 y-1)

Measure Limiting factor Theoretical Technical Economic?all agric. Given feasibleland used limitation by 2012

CroplandZero-tillage Suitable land = 63 Mha 103 89.28 8.93Reduced-tillage Suitable land = 63 Mha < 103 <9? <0.9?Set-aside <10% of arable; < 7.3 Mha 103 Max = 8.93 0 Perennial grasses andpermanent crops No incentives to grow more 165 0? 0?Deep-rooting crops Research and breeding

needed for annual crops 165 0? 0?Animal manure Manure avail. = 385 Mt dm y-1 100 86.83 ?Crop residues Surplus straw = 5.3 Mt dm y-1 185 90.46 ?Sewage sludge Sewage sludge = 71 Mt dm y-1 69 6.30 ?Composting Compost available at present

= 160 t dm y-1 (8 M ha) 100 11 11?Improved rotations 0 >0 0?Fertilisation 0 0 0Irrigation 0 0 0Bioenergy crops only current set-aside = 7.3 Mha 165 16.52 3.3Extensification current set-aside to extensify

30% of arable agr. = 20 Mha 144 41.63 ?Organic farming Could increase to 10% = 7.3 Mha 0-144 14.40 14.4

Availability of land and resources / potentialSoil carbon sequestration (Mt CO2 y-1)

Measure Limiting factor Theoretical Technical Economic?all agric. Given feasibleland used limitation by 2012

Grassland? Knowledge! ? ? ?

Revegetation

Abandoned arable land current set-aside = 7.3 Mha 165 16.52 Max. 16.52

Land conversionArable to

woodland current set-aside = 7.3 Mha 165 16.52 Max. 16.52Arable to

grassland current set-aside = 7.3Mha 140 14 0Grassland to Land-use change since 1990

arable calculated as 2.7 Mha -266 -10 (since 1990) ?Permanent crops Land-use change since 1990

to arable calculated as 0.4 Mha -42.5 -1.46 (since 1990) ?Woodland to Negligible land-use change

arable since 1990 =>-266 0 0

Availability of land and resources / potentialSoil carbon sequestration (Mt CO2 y-1)

Measure Limiting factor Theoretical Technical Economic?all agric. Given feasibleland used limitation by 2012

Farmed organic soilsProtection and Assuming all cultivated restoration organic soils are restored >36 >36 >36

More shallow Possibly attractive on grass-water table land when new melioration

is needed = 50 % of grass- 36 GHG: 36 15 15 land area = 1.5 Mha

Environmental effects

Tillage Amendments Conversion Peatland

Herbizides, pestizides

Non-CO2 gases

NH3, NOx

Biodiversity

Water quality

Soil quality

Sustainable land management

Productivity?

?

?

?

?

Best options

1 Promote organic input on arable land instead of grassland (crop residues, cover crops, FYM, compost, sewage sludge)

2 Permanent revegetation of arable set-aside land (e.g. afforestation) or extensivation of arable production by introduction of perennial components (crop rotation with ley farming)

3 Biofuel production with short-rotation coppice plantations and perennial grasses on arable set-aside land

4 Promote organic farming

5 Promote permanently shallow water table in farmed peatland

6 Zero tillage / conservation tillage

Caveats

Where are the soil / climate conditions with highest carbonsequestration potential?

Soil carbon / land use maps! Present soil C stocks?

What measures are best adjusted to regional management preferences?Regional land use / land management historyRegional best practice

Permanent, contiguous, long-term adoption of measures?Monitoring!Costs?

Regional refinement of agroenvironmental measures necessary

Research needed!

Present sources and nnual C sequestration potential in European agriculture

-80

-60

-40

-20

0

20

40

60

80

N2O-Emissionagriculture

CH4-Emissionagriculture

Current Cbalance:

mineral soils

Current Csource:

cultivatedpeatlands

Current Sink:

no-till

Potential Csink in

agriculture(by 2010)

Potential Csink in

agriculture(theoretical)

Tg C

-equ

ival

ents

/yr

Freibauer, Eur. J. Agron. 19 (2003): 135, Smith et al., GCB 2000, Janssens et al. Science (2003)

European Policy

1) European Climate Change Programme (ECCP) Working Group on Sinks Related to Agricultural Soilshttp://europa.eu.int/comm/environment/climat/eccp.htm

Recommendations for Climate PoliciesFinal report 2002

2) Environmental Technology Action Plan (ETAP)Issue Group Soilhttp://europa.eu.int/comm/environment/etap/

Recommendations for Environmental PoliciesIn progress

Conclusion of ECCP, WG Soils

Quantification of carbon sequestration potential is limited by strong regional differences in (1) the sequestration potential of the measure, (2) the environmental impact of a measure, and (3) the socio-economic impact of the measure.

Decentralised strategy, which takes into account the national, regional and even site-specific variation in socio-economic and environmental factors!

Soil carbon has important role for the vital functions of soil and contributes to the long-term maintenance of soil fertility and function.

Carbon sequestration also as a contribution to a European policy of soil protection.

Carbon sequestration in soils is likely to have only a limited potential for greenhouse gas mitigation in isolation. It needs to be part of a broader strategy of measures for greenhouse gas mitigation and would provide added value to efforts to (1) improve the sustainability of soils and agriculture through increased organic

carbon levels in soils. (2) The greatest potential: substitution of fossil fuels with bio-energy crops, which has the double benefit of offsetting carbon emissions and additional carbon sequestration in soils.

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