DAYCENT Model Description, Testing, and Application for GHG Emission Inventories

S.J Del Grosso, W.J. Parton, S.M. Ogle

Outline

• DAYCENT Description• DAYCENT Testing• Model Application: US GHG Inventory• Model Application: Biofuel LCA• COMET VR Tool for Farmers/Land

Owners

DAYCENT History• DYCENT is the daily time step version of the CENTURY

ecosystem model• CENTURY was developed in the 1970’s to investigate how

changes in land use and climate impact C and nutrient flows• Monthly time step in CENTURY is sufficient for plant growth

and decomposition• Finer resolution is needed to simulate processes that result in N

gas emissions (N2O, NOx, N2)• N2O is the primary GHG emitted form cropped soils• N2O is ~300 more potent as a GHG than CO2 (GWP = 300)• Global Warming Potential used to compare different GHG’s

DAYCENTMODEL

Land Use• Vegetation Type• Nutrient, H2O Inputs• Tillage/Harvest• Grazing/Burning

Climate• Daily Precipitation• “ Max/Min Temperature

Soil Properties• Texture• Bulk Density• FC, WP, Ksat

Trace Gas Fluxes• CO2, CH4• N2O, NOX

Plant Production• NPP Allocation• Grain Yields

SOM Changes• active/slow/recalcitrant

pools

DAYCENT: Primary Inputs/Outputs

DAYCENT MODEL

Plant Production• NPP Allocation• Crop Yields

Trace Gas Flux• CO2, CH4• N2O, NO X

SOM• Active• Slow• Passive

Soil NutrientsNO3, NH4, P, S

Land Use• Vegetation Type• Nutrient, H2O Inputs• Tillage/Harvest• Grazing/Burning

SoilH2OTemp

SoilH2OTemp

SoilH2OTemp

SoilH2OTemp

DEAD PLANTMATERIAL

METABOLIC

STRUCTURAL

PLANT COMPONENTS

LEAVES FINE ROOTS

BRANCHESLARGE WOOD

LARGEROOTS

NO3- NH4

+

0-1 cm1-4 cm4-15 cm

15-30 cmetc.

0-15 cm

SOM

ACTIVE0.5-1 yr

SLOW10-50 yr

PASSIVE1000-5000 yr

H2OsoilTsoil

0-1 cm1-4 cm

4-15 cm15-30 cm

etc.

N GAS0-1 cm1-4 cm

4-15 cm15-30 cm

etc.

C:N

CO2

S,Rh

PPT,V,L

C:N

V

SC:N

CO2

CO2

CH4Uptake

DecompRh S

Rh

S

S

NPP

DAYCENT MODEL

Parton et al. 1998Kelly et al. 2000Del Grosso et al. 2001

S=soil typeV=veg typeL=land use

ARDEC corn or corn/soy

0

100

200

300

400

500

600

20 ct 20 nt 0 ct 0 nt 20 sc 0 sc 13 ct 13 nt

gC m

-2 y

r-1

obs meansim mean

WI corn

0

50100

150200

250

300350

400450

500

0 0m 20.4 20.4m

obs mean

sim mean

Ottawa

050

100150200250300350400

corn soy corn wheat

gC m

-2 y

r-1

obs meansim mean

Iowa corn/soy

050

100150200250300350400450

low corn low soy medcorn

med soy highcorn

high soy

obs meansim mean

Crop Yield Testing

CO Irrigated Corn

KBS

050

100150200

250300350400

corn soy wheat alfalfa

gC m

-2 y

r-1

obs meansim mean

Sideney and Sterling

0

20

40

60

80

100

120

140

wheat sid wheat sterling corn sterling

obs meansim mean

TN no till corn

0

50

100

150

200

250

300

0 14 25

gC m

-2 y

r-1

obs meansim mean

WI sand

050

100150200250300350400450500

sweet corn potato

obs mean

sim mean

Crop Yield Testing

Site Level Mean N2O Emissions

05

10152025303540

CO dryla

nd whe

at

CO dryla

nd cropp

ing

NE dryla

nd w

heat

NE grass

MI corn

/soy/a

lfalfa

TN corn

CO irriga

ted co

rn

CO irriga

ted co

rn/ba

rley

CO gras

sOnta

rio co

rnPA cr

opPA gr

ass

avera

geN2

O g

N h

a-1 d

-1 measuredDAYCENTIPCC

Soil N2O Emissions Testing

Del Grossoet al.,2005, 2008

WI loam

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0m 20.4 20.4m

gN m

-2 y

r-1

mean obs

mean sim

IO loam

0

0.5

1

1.5

2

2.53

3.5

4

4.5

5

low corn low soy med corn med soy high corn high soy

gN m

-2 y

r-1

mean obs

mean sim

WI sand

0

5

10

15

20

25

sw eet corn potato

gN m

-2 y

r-1

mean obs

mean sim

NO3 LeachingTesting

Del Grossoet al.,2005

Model Application

N2O emissions from agricultural soils for US National GHG Inventory

Modeling Framework

DAYCENTModel

Mineral N Fertilization

Manure Amendments

PDF

PDF

WeatherData PDF

Input Uncertainty

Per Unit AreaEmissions

NASS Areas

Structural Uncertainty

PDF

95%ConfidenceInterval

SoilCharacter-istics

PDF

TotalEmissions

DAYMETDAYMET

NLCDNLCD

Model Input Data

Direct Soil N2O Emissions

Cropland Remaining Cropland – 2007

Total: 176.0 +48/-33% Tg CO2 eq. yr-1

Del Grossoet al.,In review

Comparing DAYCENT (Tier 3) and IPCC Method (Tier 1)

Emis

sion

s (T

g C

O2 e

q yr

-1)

-100

-50

0

50

100

150

200

250

300

Soil N2O Δ Soil Organic C

Tier 1 Tier 3 Tier 3Tier 2

+101/-69%

+48/-33%

± 16%

+50/-41%

0%

200%

400%

600%

800%

1000%

1200%

0 5 10 15 20Regional N2O Emisisons (gG N)

CI W

idth

But as Scale Decreases, confidence intervals Widen

Del Grossoet al.,In review

Model Application

Life Cycle Analysis for Biofuel Cropping Systems

DAYCENTComputer

Model

Biofuelcropping system

net GHGflux

Life cycle net greenhouse gases from bioenergy cropping systems

Daily weather

data

Croppingsystem

Land management

practices

Soil properties

System carbonchanges

Chemical inputs

Ag. machinery

Soil GHGflux

Cropyield

Feedstockconversion

Displacedfossil fuelnet GHG

Biofuel

IFSMComputer

model

+ +++ =

×Fuel

economyratio

= Fossilfuel ×

Fossil fuellife-cycleGHGs

=

(× conversion efficiency ratio)

(× net life cycle GHGs at biorefinery including co-products)

(quantity × life cycle GHGs from production)

Adler et al.,2007

Components of LCA GHGnet

10 year mean after conversion to corn for ethanol - Iowa

-800

-600

-400

-200

0

200

400

Soil GHGnet displaced feedstock inputs machinery

g C

O2 e

q m

-2 y

r-1

pasturecropcrp

100

50

0

-50

-100

-150

-200

g C

O2

–C

eq.

m-2

yr-1

-200

-100

0

100

200

illinois indiana iowa

g C

O2

eqm

-2yr

-1pasturecropcrp

-200

-100

0

100

200

illinois indiana iowa

g C

O2

eqm

-2yr

-1pasturecropcrp

-200

-100

0

100

200

illinois indiana iowa

g C

O2

eqm

-2yr

-1pasturecropcrp

-200

-100

0

100

200

illinois indiana iowa

g C

O2

eqm

-2yr

-1pasturecropcrp

50

25

0

-25

-50

g C

O2

–C

eq.

m-2

yr-1

COMET-VR Toolhttp://www.cometvr.colostate.edu/

• The Voluntary Reporting of Greenhouse Gases-CarbOnManagement Evaluation Tool (COMET-VR ) tool is a decision support tool for agricultural producers, land managers, soil scientists and other agricultural interests.

• COMET-VR provides an interface to a database containing land use data from the Carbon Sequestration Rural Appraisal (CSRA) and calculates in real time the annual carbon flux using a dynamic Century model simulation

• Will Compute N2O as well in the near future• USDA does not necessarily endorse any soil GHG accounting tool