UK ‘4 per mil’ DEBATE: organic soils Joanna Clark.pdf · WHEN IS IT PEAT? •In England and Wales (Clayden & Hollis, 1984): •>40 cm organic material within top 80 cm •In Scotland

LIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTLIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTLIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTCopyright University of Reading

UK ‘4 PER MIL’ DEBATE:ORGANIC SOILS

BSSS Meeting, 5 December 2017

Dr Joanna Clark

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Department of Geography & Environmental Science

LIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACT

OUTLINE• What are organic soils and where can we find them in the UK?

• What does ‘4 per mil’ mean for organic soils?

• How does carbon accumulate in organic soils?

• What limits carbon accumulation in organic soils?

• Opportunities to increase carbon accumulation in organic soils

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LIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACTLIMITLESS POTENTIAL | LIMITLESS OPPORTUNITIES | LIMITLESS IMPACT

WHAT ARE ORGANIC SOILS AND WHERE CAN WE FIND THEM?

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SOILS ARE NOT EQUAL, SOILS ARE DIVERSE

Images: www.macaulay.ac.uk/host

Peat Peaty podzol Gley Brown Earth

Upland Climate: Cool & Wet Lowland Climate: Warm & Dry

Poor drainage Good drainage Poor drainage Good drainage


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Jenny (1941)

Parent material

Topography

Organisms

Time

Climate

Soil Forming Factors


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Jenny (1941)

Parent material

Topography

Organisms

Time

Climate

Peat

Impeded drainage

Shallow slopes

Wet and cool

1000s yrs

No earthworms


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PEAT GROWS• Litter accumulates in

layers

• No earthworms, no mixing

• Mineral material (if any) below peat layerCan reach depths of 8 m or more


WHEN IS IT PEAT?• In England and Wales (Clayden &

Hollis, 1984):

• >40 cm organic material within top 80 cm

• In Scotland (Chapment et al , 2009)

• Organic deposit (>60% OM)

• >50cm depth

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Natural England Technical Information Note TIN037


‘PEATY’ SOILS ARE MAINLY IN THE UPLANDS

Soil Upland Lowland All

Peat soils 11.8% 0.9% 3.0%

Blanket peat 11.4% <0.1% 2.2%

Raised bog 0.4% 0.2% 0.3%

Fen peat <0.1% 0.7% 0.6%

Humic rankers 3.7% <0.1% 0.7%

Stagnopodzols 11.6% 0.2% 2.4%

Stagnohumic

gley soils

17.4% 0.3% 3.6%

Humic gley soils - 0.3% 0.3%

Pelo alluvial gley

soils

- 0.3% 0.2%

All peaty soils 44.5% 2.0% 10.2

%

NATMAPVector, Cranfield UniversityNB: Upland defined by SDA


BLANKET PEAT CONTROLLED BY CLIMATE

Blanket peat Mean annual temperature(1961-1990)

Total annual precipitation(1961-1990)


WHAT DOES ‘4 PER MIL’ MEAN FOR ORGANIC SOILS?

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• Global soils contain 2 to 3 times more carbon than the atmosphere.

• If this carbon level was increased by 0.4%, or 4‰ per year, in the top 30-40 cm of soils, the annual increase in carbon dioxide (CO2) in the atmosphere would be stopped.

• This is what the 4 per 1000 Initiative proposes, soils for food security and climate.

www.4p1000.org


0.4% C INCREASE IN UK PEAT • Using values in Billett et al (2010)……..

• UK peatland area is 24640 km2 with carbon stock of 2302 MtC

• Average peatland carbon density 93.4 kg C/m2

• 0.4% increase in stock

• 374 g C/m2/yr in total

• 253 g C/m2/yr in top 1m

• 101 g C/m2/yr in top 40 cm

• Observed rates across the UK

• 56 to 72 gC/m2/yr from monitoring data

• 35 to 209 g C/m2/yr from peat cores 13


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BUT, PEAT GROWS• In top 1m,

63 g/m2/mm

• 0.4% increase of top 40 cm C stock is 1.6mm/yr depth


HOW DOES CARBON ACCUMULATE IN ORGANIC SOILS?

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Source (fluxes from air to land):

plant tissue (leaves, stems, roots etc…) (i.e. fixed CO2)

Sink (fluxes from land to air):

carbon dioxide (CO2)

methane (CH4)

dissolved organic carbon (DOC)

dissolved inorganic carbon (DIC) particulate organic carbon (POC)

CO2 CH4

ca. 90% peat is water

POC

DOC

DIC

Peatland carbon cycle

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WHAT LIMITS CARBON ACCUMULATION IN ORGANIC SOILS?

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CARBON BALANCE OF HEALTHY VS DEGRADED PEATLAND

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‘Healthy’ Peatland

Atmosphere

CO2/CH4

Exchange

‘Degraded’ Peatland

Atmosphere

CO2/CH4

Exchange

DOC/POCDOC/POC


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PEATLAND DEGRADATION BY EROSIONwww.shetlandamenity.org


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PEATLAND DRAINAGE AND AFFORESTATION

http://www.rspb.org.uk


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PEATLAND DRAINAGE FOR AGRICULTURE (HOLME FEN)


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AGRICULTURE ON LOWLAND PEAT

http://www.countryfile.com


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GRAZING PRESSURE


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MOORLAND BURNING

www.york.ac.uk


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DEGRADATION BY ACID DEPOSITION



REGIONAL CLIMATE VULNERABILITYKey Region Peat area (%) Rank

Northumbria 2.1 1

Dartmoor, Exmoor & Bodmin

moor

0.9 2

Peak District 3.0 3

Brecon Beacons & South Wales 0.3 4

North York Moors 0.3 5

Orkney 0.7 6

Central Belt 1.5 7

North Pennines 4.5 8

Ayrshire, Dumfris & Galloway 4.1 9

Caithness & East Sutherland 12.0 10

Yorkshire Dales & Bowland 4.8 11

Cambrian Mountains 1.3 12

Scottish Boarders 2.0 13

Snowdonia & North Wales 2.5 14

Grampians 4.5 15

Western Isles 8.6 16

Argyle, Bute & Trossachs 13.5 17

Cumbria Fells & Dales 1.2 18

Shetland 4.1 19

Highlands 25.2 20

5 regions

at lower

limit of

bioclimatic

space


OPPORTUNITIES TO INCREASE CARBON ACCUMULATIONIN ORGANIC SOILS

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STOP THE LOSS: STABILISE SURFACE• Erosions rates vary

from 3.4-96 g C/m2/yr(Billett et al. 2010)

http://www.moorsforthefuture.org.uk


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STOP THE LOSS: REWETwww.iucn-uk-peatlandprogramme.org


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STOP THE LOSS: REWET

Evans et al (2017)

Study of lowland peatland sites, every 10 cm increase in water-table depth, CO2 emissions increase by around 4 t CO2-eq/ha/yrOr400 g CO2-eq/m2/yr


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GROW THE CARBON

data.wildlifetrusts.org


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MAXIMISE INPUTS BY MINIMISING GRAZING AND BURNING?

https://northyorkmoorsnationalpark.files.wordpress.com


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So, for organic soils…..

‘4 per mil’

Or

‘4 mm’

Stop the loss and grow carbon

Documents

UK ‘4 per mil’ DEBATE: organic soils Joanna Clark.pdf · WHEN IS IT PEAT? •In England and Wales (Clayden & Hollis, 1984): •>40 cm organic material within top 80 cm •In Scotland