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Pre-workshop exercise on SOC stocksimulation / calibration of DNDC
Steven SleutelDept. Soil Management & Soil Care
Ghent University
S.Sleutel, 19.10.2005
DNDC model
DNDC: C and N bio-geochemical model Li et al. (1992; 1994)
2 components: 1° soil climate, crop growth, decomposition 2° nitrification, denitrification, fermentation
4 SOC pools (litter, microbial biomass, active humus, passive humus)
Daily time steps
possibilities to define “management” (tillage, N-fertilization, manuring, cropping dates)
S.Sleutel, 19.10.2005
DNDC model stucture
(process oriented, 6 different sub-modules)
Ecological
driversClimate Soil Vegetation Human activity
Annualaveragetemp.
LAI-regulatedalbedo.
Soil temp.profile
Soilenvironmentalfactors
Soil moist.profile
Potentialevapotrans.
evap. trans.Verticalwaterflow
O2diffusion
Soil Ehprofile
O2 use
Soil climate
Water demand
Water uptake
Water stressN-uptake
N-demand
Daily growth
grain
stems
rootsRoot respiration
Plant growth
Very labile Labile Resistant
CO2
Labile Resistant
Labile Resistant
Passive humus
NH4+
DOC
Decomposition
litter
microbes
humads
Effect of temperature and moisture on decomposition
NO
N2O
N2
NO2-
Nitratedenitrifier
Nitritedenitrifier
N2Odenitrifier
DOC
NO3-
Denitrification
Temperature Moisture pH
DOC
NO3-
NH4+nitrifiers
NH3 ClayNH4
+
NH3NON2O
Nitrification
Eh Substrates: NH4+, NO3
-, DOC
Fermentation
Soil Eh
aerenchyma
DOCCH4 transport
CH4 oxidation
CH4 production CH4
INPUT
SOIL VAR.
decomposition
CO2
S.Sleutel, 19.10.2005
DNDC model
Own Interest: prediction SOC stock changes cropland soils
(regional scale: SOC storage potential)
denitrification – fermentation –SOC cycle plant phenological growth sub modules
“User” -> limited access to parameterization specific model processes
S.Sleutel, 19.10.2005
Model exercise data input
1. Climate: daily T° and precipitation
2. Soil variables:
bulk density, SOC conc., pH, clay content, moisture content at wilting point and field capacity, land-use
3. Management:
crop rotation and dates of sowing and harvest, tillage, N-fertilization, manuring
Specific DNDC paramerization for model exercise Partitioning of C and N in crop parts – C:N ratio’s crop yields at optimum conditions (N, water, temp.) Initial partitioning of SOC in model pools “Soil microbial activity index”
S.Sleutel, 19.10.2005
Proposed model simulations
Calibration step
Calibration plot Simulation plot Observations for comparison
I Calibration on Corg content and CO2
emission of the trace gas measurement field (1 year)
Simulating the bare fallow plot of the short term experiment (5 years)
Organic carbon content
II a Calibration on plant development of crop rotation plot (V521_12, 7 years)
Simulating the 100 years NPK plot (plot 13)
Yield, nitrogen removal
II b Calibration on Corg content (and soil
moisture) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content
II c Calibration on Corg content, soil
moisture and inorganic nitrogen (soil and soil solution) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content, inorganic nitrogen in soil
S.Sleutel, 19.10.2005
Proposed model simulations
Calibration step
Calibration plot Simulation plot Observations for comparison
I Calibration on Corg content and CO2
emission of the trace gas measurement field (1 year)
Simulating the bare fallow plot of the short term experiment (5 years)
Organic carbon content
II a Calibration on plant development of crop rotation plot (V521_12, 7 years)
Simulating the 100 years NPK plot (plot 13)
Yield, nitrogen removal
II b Calibration on Corg content (and soil
moisture) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content
II c Calibration on Corg content, soil
moisture and inorganic nitrogen (soil and soil solution) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content, inorganic nitrogen in soil
S.Sleutel, 19.10.2005
Parmeter sets
Parameter default
Crop C:N ratio + C-partitioning
Default DNDC
Opt crop yield Default DNDC
SOC partitioning Default DNDC
Microbial activity index
Default DNDC
S.Sleutel, 19.10.2005
Calibration of crop param. Plot12
Large underestimation of crop yields
adjust DNDC’s crop par. to 1°
2°
3°
Simulated - Measured DM yield
-8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0
WW
SB
B
PO
WW
SB
B
DM Yield (kg DM / ha)
Year 1-2
Year 8
S.Sleutel, 19.10.2005
Calibration of crop param. Plot 12
Large underestimation of crop yields
adjust DNDC’s crop par. to 1° starting date of growth of grain
2°
3°
Simulated - Measured DM yield
-8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000
WW
SB
B
PO
WW
SB
B
DM Yield (kg DM / ha)
Spring
barley
S.Sleutel, 19.10.2005
Calibration of crop param. Plot 12
Large underestimation of crop yields
adjust DNDC’s crop par. to 1° starting date of growth of grain
2° measured C and N content plant parts
partitioning C plant parts (grain / shoot / root)
3°
Simulated - Measured DM yield
-8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000
WW
SB
B
PO
WW
SB
B
DM Yield (kg DM / ha)
S.Sleutel, 19.10.2005
Calibration of crop param. Plot 12
Simulated - Measured DM yield
-2500 -2000 -1500 -1000 -500 0 500 1000
WW
SB
B
PO
WW
SB
B
DM Yield (kg DM / ha)
Large underestimation of crop yields
adjust DNDC’s crop par. to 1° starting date of growth of grain
2° measured C and N content plant parts
partitioning C plant parts (grain / shoot / root)
3° DNDC par. “optimum yield”
S.Sleutel, 19.10.2005
Parameter default Set1
Crop C:N ratio + C-partitioning
Default DNDC
plot12
Opt crop yield Default DNDC
Default DNDC
SOC partitioning Default DNDC
Default DNDC
Microbial activity index
Default DNDC
Default DNDC
S.Sleutel, 19.10.2005
Proposed model simulations
Calibration step
Calibration plot Simulation plot Observations for comparison
I Calibration on Corg content and CO2
emission of the trace gas measurement field (1 year)
Simulating the bare fallow plot of the short term experiment (5 years)
Organic carbon content
II a Calibration on plant development of crop rotation plot (V521_12, 7 years)
Simulating the 100 years NPK plot (plot 13)
Yield, nitrogen removal
II b Calibration on Corg content (and soil
moisture) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content
II c Calibration on Corg content, soil
moisture and inorganic nitrogen (soil and soil solution) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content, inorganic nitrogen in soil
S.Sleutel, 19.10.2005
Simulation of SOC stock evolution plot 13
crop rotation with 4 crops SB – B – PO – WW
Average figures: yield (kg DM)
fertilization (type, amount, date)
tillage (depth, date)
sowing and harvest date
2 crop rotations: management changes with time: higher N-fertilization (1° 70y; 2° 30y)
Crop rot. 1 Crop rot. 2 higher N-fert.
1902 1972 2002
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13) default DNDC crop par.
Underestimation of crop yields
Simulated and measured crop yields
0
2000
4000
6000
8000
10000
12000
sugar beets springbarley
potato winter wheat
kg D
M h
a-1
y-1
simulated
measured
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)with crop par. ~ plot 12
Overestimation of crop yield PO
Simulated and measured crop yields
0
2000
4000
6000
8000
10000
12000
sugar beets springbarley
potato winter wheat
kg D
M h
a-1
y-1
simulated
measured
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)default DNDC crop parameters
0,012
0,014
0,016
0,018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)crop parameters adj. plot 12
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
Large underestimation SOC conc. Further calibration DNDC
on plot 12:Calibration II.b
S.Sleutel, 19.10.2005
Proposed model simulations
Calibration step
Calibration plot Simulation plot Observations for comparison
I Calibration on Corg content and CO2
emission of the trace gas measurement field (1 year)
Simulating the bare fallow plot of the short term experiment (5 years)
Organic carbon content
II a Calibration on plant development of crop rotation plot (V521_12, 7 years)
Simulating the 100 years NPK plot (plot 13)
Yield, nitrogen removal
II b Calibration on Corg content (and soil
moisture) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content
II c Calibration on Corg content, soil
moisture and inorganic nitrogen (soil and soil solution) of crop rotation plot (V521_12, 7 years)
Simulating the 100 years nil (plot18) and NPK plot (plot 13) and perhaps additionally the farm yard manure (FYM, plot 6) and the NPK plus FYM plot (plot 1)
Organic carbon content, inorganic nitrogen in soil
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12
Opt crop yield Default DNDC
Default DNDC
plot12
SOC partitioning Default DNDC
Default DNDC
???
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
S.Sleutel, 19.10.2005
Simulation 8y plot 12
overestimation SOC conc. Adjust initial partitioning DNDC’s
SOC pools
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c. k
g C
kg
-1 s
oil
measured SOC
simulated SOC
(default = 80 % humus)
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12
Opt crop yield Default DNDC
Default DNDC
plot12
SOC partitioning Default DNDC
Default DNDC
Default DNDC
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
0.0009Tot. RMSE (kg OC kg-1 soil)
S.Sleutel, 19.10.2005
Simulation 8y plot 12
overestimation SOC conc. Adjust initial partitioning DNDC’s
SOC pools
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c. k
g C
kg
-1 s
oil
measured SOC
simulated SOC
(default = 80 % humus)
S.Sleutel, 19.10.2005
Simulation 8y plot 12
overestimation SOC conc. Adjust initial partitioning DNDC’s
SOC pools
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c. k
g C
kg
-1 s
oil
measured SOC
simulated SOC
(75 % humus)
S.Sleutel, 19.10.2005
Simulation 8y plot 12
overestimation SOC conc. Adjust initial partitioning DNDC’s
SOC pools
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c. k
g C
kg
-1 s
oil
measured SOC
simulated SOC
(70 % humus)
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2 Set 3
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12 plot12
Opt crop yield Default DNDC
Default DNDC
plot12 plot12
SOC partitioning Default DNDC
Default DNDC
Default DNDC
Plot12
(70%H)
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
Default DNDC
0.00072Tot. RMSE plot 12 (kg OC kg-1 soil) 0.0009
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
default DNDC 80% humus Calibration
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
70% humus ~ calibration plot 12
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
Worse simulation of SOC conc.
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2 Set 3 Set 4
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12 plot12 plot12
Opt crop yield Default DNDC
Default DNDC
plot12 plot12 plot12
SOC partitioning Default DNDC
Default DNDC
Default DNDC
Plot12
(70%H)
Plot12
(70%H)
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
Default DNDC
Plot 12
????
0.00072Tot. RMSE plot 12 (kg OC kg-1 soil) 0.0009
S.Sleutel, 19.10.2005
Simulation 8y plot 12
Adjust DNDC’s “Microbial Activity Index” (0-1)
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c. k
g C
kg
-1 s
oil
measured SOC
simulated SOC
Default value 1
S.Sleutel, 19.10.2005
Simulation 8y plot 12
Adjust DNDC’s “Microbial Activity Index” (0-1)
0.9
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c.
kg
C k
g-1
so
il
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 8y plot 12
Adjust DNDC’s “Microbial Activity Index” (0-1)
0.8
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c.
kg
C k
g-1
so
il
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 8y plot 12
Adjust DNDC’s “Microbial Activity Index” (0-1)
0.7
0.018
0.019
0.020
0.021
0.022
1997 1998 1999 2000 2001 2002 2003 2004
SO
C c
on
c.
kg
C k
g-1
so
il
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2 Set 3 Set 4
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12 plot12 plot12
Opt crop yield Default DNDC
Default DNDC
plot12 plot12 plot12
SOC partitioning Default DNDC
Default DNDC
Default DNDC
Plot12
(70%H)
Plot12
(70%H)
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
Default DNDC
Plot 12
(0.9)
0.00072Tot. RMSE plot 12 (kg OC kg-1 soil) 0.0009 0.00073
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
70% humus ~ calibration plot 12
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
Microbial Activity index = 1 (default DNDC)
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
70% humus ~ calibration plot 12
Microbial Activity index = 0.9 ~ plot 12
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
Almost no
improvement
S.Sleutel, 19.10.2005
Simulation 100y nil (plot 18)
80% humus (default DNDC)
Microbial Activity index = 1 (default DNDC)
0,010
0,012
0,014
0,016
0,018
0,020
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 100y nil (plot 18)
70% humus
Microbial Activity index = 0.9~ plot 12
0,010
0,012
0,014
0,016
0,018
0,020
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Parameter default Set1 Set 2 Set 3 Set 4 Set 5
Crop C:N ratio + C-partitioning
Default DNDC
plot12 plot12 plot12 plot12 Plot12
Opt crop yield Default DNDC
Default DNDC
plot12 plot12 plot12 plot12
SOC partitioning Default DNDC
Default DNDC
Default DNDC
Plot12
(70%H)
Plot12
(70%H)90%H
Microbial activity index
Default DNDC
Default DNDC
Default DNDC
Default DNDC
Plot 12
(0.9)<0.7
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
70% humus ~ calibration plot 12
Microbial Activity index = 0.9 ~ plot 12
0.012
0.014
0.016
0.018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
Slightly
better
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
90% humus
Microbial Activity index = 0.7
0,012
0,014
0,016
0,018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
~ plot 12
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
90% humus
Microbial Activity index = 0.6~ plot 12
0,012
0,014
0,016
0,018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 100y NPK (plot 13)
90% humus
Microbial Activity index = 0.5~ plot 12
0,012
0,014
0,016
0,018
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 100y nil (plot 18)
70% humus
Microbial Activity index = 0.9~ plot 12
0,010
0,012
0,014
0,016
0,018
0,020
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 100y nil (plot 18)
90% humus
Microbial Activity index = 0.6~ plot 12
0,010
0,012
0,014
0,016
0,018
0,020
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated SOC
S.Sleutel, 19.10.2005
Simulation 100y FYM (plot 6)
70% humus
Microbial Activity index = 0.9~ plot 12
0,016
0,018
0,020
0,022
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
Better result:
Plot 6 OM input
~correspond
To plot 12
S.Sleutel, 19.10.2005
Simulation 100y FYM (plot 6)
90% humus
Microbial Activity index = 1
0,016
0,018
0,020
0,022
1902 1922 1942 1962 1982 2002
year
SO
C (
kg C
kg
-1)
measured SOC
simulated
S.Sleutel, 19.10.2005
conclusions
Good Calibration plot 12 -> bad result sim. plots:
impossible to estimate error for long-term aplic.
8y is too short to calibrate SOC pool partitioning, which has a large impact on the final result of the long-term simulations
“correspondence in management” between calibration plot and simulation plots is necessary:
plot 12 – plot 13 & 18
Calibration of other parameters DNDC: specific decomposition rates SOC pools,
Simplicity of DNDC: partitioning of fresh OM based only on C:N-ratio
Requiered data: partitioning of SOM??