Carbon losses from all soils across England and Wales 1978-2003 Pat Bellamy, Peter Loveland, Ian Bradley, Murray Lark (Rothamsted), Guy Kirk [email protected].

Carbon losses from all soils across England

and Wales 1978-2003

Pat Bellamy, Peter Loveland, Ian Bradley, Murray Lark (Rothamsted), Guy

Kirk

[email protected]

Nature 437, 245-248 (2005)

1:250,000 scale 1:50,000 scale

Availability of Soil Surveys in Europe, 2000

The National Soil Inventory

Unbiased inventory of soil resources across England & Wales at intersects of 5 km x 5 km grid

Whole of E&W sampled in 1979-83 (5,662 sites)

Approx. 40% of sites re-sampled: agricultural 1994-96, non-agricultural 2002-03

Organic carbon content of 0-15 cm soil (Corg) measured

Sampling scheme designed to detect changes of ± 2 g kg-1

Checks on methods – accuracy of relocation

Six surveyors instructed to revisit 10 sites following original protocols 0

20

40

60

80

0

20

40

60

80

Soi

l org

anic

C c

onte

nt (g

kg

-1)

0

20

40

60

80

0

20

40

60

80

0

20

40

60

80

0

20

40

60

80

0

20

40

60

80

0

50

100

150

200

250

Distance from original site (m)

020406080

100120140

0

20

40

60

80Site 1 Site 2 Site 3

Site 4 Site 5 Site 6

Site 7 Site 8 Site 9

Site 10

0 10 500 10 50 0 10 50

0 10 500 10 50 0 10 50

0 10 500 10 50 0 10 50

0 10 50

Accuracy better than 20 m on enclosed land, 50 m on open land

Locations recorded with GPS; distance from target measured subsequently

Given the variability of Corg at this scale, this is adequate

Checks on methods – consistency of lab. analyses

Approx. 10% of archived soils from original sampling re-analysed in 2003

Original Corg (g kg-1)

0 100 200 300 400 500

Re-

anal

ysed

Co

rg (

g k

g-1

)

0

100

200

300

400

500

Good agreement between original and re-analysed values with no systematic deviation (slope of reduced major axis correlation = 1.05, concordance correlation = 0.93)

Original soil organic carbon contents (1978/83)

Original soil organic carbon contents (1978/83) and rates of change

Rates of change - grouped by (a) soil type, (b) land use

Rat

e o

f ch

ang

e(g

kg

-1 y

r-1)

-6

-4

-2

0

2

(a) Soil type (b) Land use

Rates of change - grouped by original Corg

0 100 200

Rat

e o

f ch

ang

e(g

kg

-1 y

r-1)

-8

-6

-4

-2

0

2

Corg (g kg-1)

0 100 200 0 100 200 300 400 500

(a) Arable/rotational grass

(b) Permanentgrass (c) Non-agricultural

Rates of change - grouped by original Corg

Corg (g kg-1)

0 100 200 300 400 500

Rat

e o

f ch

ang

e(g

kg

-1 y

r-1)

-8

-6

-4

-2

0

2All land uses

Eqn (1)

Eqn (1): Rate of change = 0.6 - 0.0187 × original Corg

Estimated changes in carbon stocksacross England & Wales (and UK)

Original Corg (g kg-1)

% o

f ar

ea o

f E

&W

0

5

10

15

20

25

30

0-20

> 3

00

100-

200

30-5

0

20-3

0

50-1

00

200-

300 R

ate

of

chan

ge,

Mt

yr-1

-3

-2

-1

0

1

2

0-20

> 3

00

100-

200

30-5

0

20-3

0

50-1

00

200-

300

Net rate of change in England & Wales = - 4.4 Mt yr-1

Net rate of change in UK ≈ - 4.4 x UK / E&W topsoil OC stock≈ -13 Mt yr-1

% o

f to

tal O

C s

tock

0

5

10

15

20

25

30

0-20

> 3

00

100-

200

30-5

0

20-3

0

50-1

00

200-

300

OC stock = Corg x BD x depth x area

where BD = 1.3 – {0.275 ln(Corg/10)}

Changes in carbon stocks across E&W – grouped by land use

% o

f are

a0

10

20

30

40

Rat

e of

cha

nge,

Mt y

r-1

-1.5

-1.0

-0.5

0.0

0.5

1.0

Dynamics of soil organic carbon (SOC)

CO2, CH4

Carbon immobilization

Plant debris

(high temperature, rainfall, land use)

Leached OC

Carbon accumulation

><

Carbon loss

SOC ‘pools’• fast• intermediate• slow

Carbon mobilization

(Fe, Al, clay association)

input + immobilization mobilization + output

After Schultze, E.D. & Freibauer A. Nature 437, 205-206 (2005)

Modelling soil carbon dynamics

CO2

Fast POCSlow POC

Fast SOC (C1)

Intermediate SOC (C2)

Slow SOC (C3)

CO2

CO2 CO2

CO2

decomp. rate = k1C1

decomp. rate = k2C2

decomp. rate = k3C3

SOIL POOLS

PLANTDEBRIS

Rate constants (ki) vary with soil temperature (T), moisture (θ), texture (t):ki = f(T) f(θ) f(t) ki

0

Changes in carbon stocks across E&W – grouped by soil type

% o

f are

a0

10

20

30

40

Rat

e of

cha

nge,

Mt y

r-1

-1.5

-1.0

-0.5

0.0

0.5

Most important soil types

Ah

Bh

Bs

BC & Bs

Ea

BC & Ea

Ah

Bh

Bs

BC & Bs

Ea

BC & Ea

A

E

B

A

E

B

Surface water gleysSlowly permeable, seasonally wet

Podzolic soilsAcid sands or loams with leached organic matter & sesquioxides, wet or dry

Ah

Ea

Bs

Bh

BC&Bs

BC&Ea

Peat soilsPermanently or seasonally wet

Modelling soil carbon dynamics

CO2

Fast plant OCSlow plant OC

Fast SOC (C1)decomp. rate = k1C1

Intermediate SOC (C2)decomp. rate = k2C2

Slow SOC (C3)decomp. rate = k3C3

CO2

CO2 CO2

CO2

Rate constants (ki) vary with soil temperature (T), moisture (θ), texture (t):ki = f(T) f(θ) f(t) ki

0

SOIL POOLS

PLANTDEBRIS

Organic Carbon (%) No Data 0 - 1 1 - 2 2 - 5 5 - 10 10 - 25 25 - 35 > 35

Soil carbon map of EuropeData sourcesSoil typeLand coverTemperature

Rasterization Spatial layers derived by rasterization of a Triangulated Irregular Network (TIN) model with weighted distance interpolationSoil type

Temperature

Future research

Third sampling of NSI- plus carbon fluxes (to air and water)- plus additional data

Modelling - statistical- semi-empirical- predictive

Similar studies elsewhere