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Pre-workshop exercise on SOC stock simulation / calibration of DNDC Steven Sleutel Dept. Soil Management & Soil Care Ghent University.

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Presentation on theme: "Pre-workshop exercise on SOC stock simulation / calibration of DNDC Steven Sleutel Dept. Soil Management & Soil Care Ghent University."— Presentation transcript:

1 Pre-workshop exercise on SOC stock simulation / calibration of DNDC Steven Sleutel Dept. Soil Management & Soil Care Ghent University

2 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)

3 S.Sleutel, 19.10.2005 DNDC model stucture (process oriented, 6 different sub-modules) INPUT SOIL VAR. decomposition CO 2

4 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

5 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”

6 S.Sleutel, 19.10.2005 Proposed model simulations Calibration step Calibration plotSimulation plotObservations for comparison ICalibration on C org content and CO 2 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 aCalibration on plant development of crop rotation plot (V521_12, 7 years) Simulating the 100 years NPK plot (plot 13) Yield, nitrogen removal II bCalibration on C org 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 cCalibration on C org 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

7 S.Sleutel, 19.10.2005 Proposed model simulations Calibration step Calibration plotSimulation plotObservations for comparison ICalibration on C org content and CO 2 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 aCalibration on plant development of crop rotation plot (V521_12, 7 years) Simulating the 100 years NPK plot (plot 13) Yield, nitrogen removal II bCalibration on C org 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 cCalibration on C org 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

8 S.Sleutel, 19.10.2005 Parmeter sets Parameterdefault Crop C:N ratio + C- partitioning Default DNDC Opt crop yieldDefault DNDC SOC partitioningDefault DNDC Microbial activity index Default DNDC

9 S.Sleutel, 19.10.2005 Calibration of crop param. Plot12 Large underestimation of crop yields adjust DNDC’s crop par. to 1° 2° 3° Year 1-2 Year 8

10 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° Spring barley

11 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°

12 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° DNDC par. “optimum yield”

13 S.Sleutel, 19.10.2005 ParameterdefaultSet1 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC SOC partitioningDefault DNDC Microbial activity index Default DNDC

14 S.Sleutel, 19.10.2005 Proposed model simulations Calibration step Calibration plotSimulation plotObservations for comparison ICalibration on C org content and CO 2 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 aCalibration on plant development of crop rotation plot (V521_12, 7 years) Simulating the 100 years NPK plot (plot 13) Yield, nitrogen removal II bCalibration on C org 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 cCalibration on C org 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

15 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 19722002

16 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) default DNDC crop par. Underestimation of crop yields

17 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) with crop par. ~ plot 12 Overestimation of crop yield PO

18 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) default DNDC crop parameters

19 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) crop parameters adj. plot 12 Large underestimation SOC conc. Further calibration DNDC on plot 12: Calibration II.b

20 S.Sleutel, 19.10.2005 Proposed model simulations Calibration step Calibration plotSimulation plotObservations for comparison ICalibration on C org content and CO 2 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 aCalibration on plant development of crop rotation plot (V521_12, 7 years) Simulating the 100 years NPK plot (plot 13) Yield, nitrogen removal II bCalibration on C org 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 cCalibration on C org 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

21 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC ??? Microbial activity index Default DNDC

22 S.Sleutel, 19.10.2005 Simulation 8y plot 12 overestimation SOC conc. Adjust initial partitioning DNDC’s SOC pools (default = 80 % humus)

23 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC Microbial activity index Default DNDC 0.0009 Tot. RMSE (kg OC kg -1 soil)

24 S.Sleutel, 19.10.2005 Simulation 8y plot 12 overestimation SOC conc. Adjust initial partitioning DNDC’s SOC pools (default = 80 % humus)

25 S.Sleutel, 19.10.2005 Simulation 8y plot 12 overestimation SOC conc. Adjust initial partitioning DNDC’s SOC pools (75 % humus)

26 S.Sleutel, 19.10.2005 Simulation 8y plot 12 overestimation SOC conc. Adjust initial partitioning DNDC’s SOC pools (70 % humus)

27 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2Set 3 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC Plot12 (70%H) Microbial activity index Default DNDC 0.00072 Tot. RMSE plot 12 (kg OC kg -1 soil) 0.0009

28 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) default DNDC 80% humus Calibration

29 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 70% humus ~ calibration plot 12 Worse simulation of SOC conc.

30 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2Set 3Set 4 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC Plot12 (70%H) Plot12 (70%H) Microbial activity index Default DNDC Plot 12 ???? 0.00072 Tot. RMSE plot 12 (kg OC kg -1 soil) 0.0009

31 S.Sleutel, 19.10.2005 Simulation 8y plot 12 Adjust DNDC’s “Microbial Activity Index” (0-1) Default value 1

32 S.Sleutel, 19.10.2005 Simulation 8y plot 12 Adjust DNDC’s “Microbial Activity Index” (0-1) 0.9

33 S.Sleutel, 19.10.2005 Simulation 8y plot 12 Adjust DNDC’s “Microbial Activity Index” (0-1) 0.8

34 S.Sleutel, 19.10.2005 Simulation 8y plot 12 Adjust DNDC’s “Microbial Activity Index” (0-1) 0.7

35 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2Set 3Set 4 Crop C:N ratio + C- partitioning Default DNDC plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC Plot12 (70%H) Plot12 (70%H) Microbial activity index Default DNDC Plot 12 (0.9) 0.00072 Tot. RMSE plot 12 (kg OC kg -1 soil) 0.00090.00073

36 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 70% humus ~ calibration plot 12 Microbial Activity index = 1 (default DNDC)

37 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 70% humus ~ calibration plot 12 Microbial Activity index = 0.9 ~ plot 12 Almost no improvement

38 S.Sleutel, 19.10.2005 Simulation 100y nil (plot 18) 80% humus (default DNDC) Microbial Activity index = 1 (default DNDC)

39 S.Sleutel, 19.10.2005 Simulation 100y nil (plot 18) 70% humus Microbial Activity index = 0.9 ~ plot 12

40 S.Sleutel, 19.10.2005 ParameterdefaultSet1Set 2Set 3Set 4Set 5 Crop C:N ratio + C- partitioning Default DNDC plot12 Plot12 Opt crop yieldDefault DNDC plot12 SOC partitioningDefault DNDC Plot12 (70%H) Plot12 (70%H) 90%H Microbial activity index Default DNDC Plot 12 (0.9) <0.7

41 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 70% humus ~ calibration plot 12 Microbial Activity index = 0.9 ~ plot 12 Slightly better

42 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 90% humus Microbial Activity index = 0.7 ~ plot 12

43 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 90% humus Microbial Activity index = 0.6 ~ plot 12

44 S.Sleutel, 19.10.2005 Simulation 100y NPK (plot 13) 90% humus Microbial Activity index = 0.5 ~ plot 12

45 S.Sleutel, 19.10.2005 Simulation 100y nil (plot 18) 70% humus Microbial Activity index = 0.9 ~ plot 12

46 S.Sleutel, 19.10.2005 Simulation 100y nil (plot 18) 90% humus Microbial Activity index = 0.6 ~ plot 12

47 S.Sleutel, 19.10.2005 Simulation 100y FYM (plot 6) 70% humus Microbial Activity index = 0.9 ~ plot 12 Better result: Plot 6 OM input ~correspond To plot 12

48 S.Sleutel, 19.10.2005 Simulation 100y FYM (plot 6) 90% humus Microbial Activity index = 1

49 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??


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