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