Pre-workshop exercise on SOC stock simulation / calibration of DNDC

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)


II c Calibration on Corg content, soil

moisture and inorganic nitrogen (soil and soil solution) of crop rotation plot (V521_12, 7 years)


Organic carbon content, inorganic nitrogen in soil

S.Sleutel, 19.10.2005


Calibration step

















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


adjust DNDC’s crop par. to 1° starting date of growth of grain

2°

3°


-8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000

WW

SB

B

PO

WW

SB

B


Spring

barley

S.Sleutel, 19.10.2005




2° measured C and N content plant parts

partitioning C plant parts (grain / shoot / root)

3°


-8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000

WW

SB

B

PO

WW

SB

B


S.Sleutel, 19.10.2005



-2500 -2000 -1500 -1000 -500 0 500 1000

WW

SB

B

PO

WW

SB

B




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


Default DNDC

plot12


Default DNDC


Default DNDC


Default DNDC

Default DNDC

S.Sleutel, 19.10.2005


Calibration step

















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


Calibration step

















S.Sleutel, 19.10.2005

Parameter default Set1 Set 2


Default DNDC

plot12 plot12


Default DNDC

plot12


Default DNDC

???


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


Default DNDC

plot12 plot12


Default DNDC

plot12


Default DNDC

Default DNDC


Default DNDC

Default DNDC

Default DNDC

0.0009Tot. RMSE (kg OC kg-1 soil)

S.Sleutel, 19.10.2005



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



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



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


Default DNDC

plot12 plot12 plot12


Default DNDC

plot12 plot12


Default DNDC

Default DNDC

Plot12

(70%H)


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


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


Default DNDC

plot12 plot12 plot12 plot12


Default DNDC



Default DNDC

Default DNDC

Plot12

(70%H)

Plot12

(70%H)


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


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



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



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



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


Default DNDC



Default DNDC



Default DNDC

Default DNDC

Plot12

(70%H)

Plot12

(70%H)


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



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



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


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


Default DNDC

plot12 plot12 plot12 plot12 Plot12


Default DNDC



Default DNDC

Default DNDC

Plot12

(70%H)

Plot12

(70%H)90%H


Default DNDC

Default DNDC

Default DNDC

Default DNDC

Plot 12

(0.9)<0.7

S.Sleutel, 19.10.2005



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


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


90% humus


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


90% humus


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


70% humus


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


90% humus


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


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??

Documents

Pre-workshop exercise on SOC stock simulation / calibration of DNDC