Emission factors for N 2 O and NO from agricultural soils in Belgium Pascal Boeckx, Annick Goossens & Oswald Van Cleemput Ghent University Belgium.

Emission factors for NEmission factors for N22O and O and NO from agricultural soils in NO from agricultural soils in BelgiumBelgium

Pascal Boeckx, Annick Goossens & Oswald Van Cleemput

Ghent UniversityBelgium

Lay outLay out

Long-term field experiments of N2O and NO

fluxes from agricultural soils– Field set-up– Results– Emission factors

Inventories: IPCC 1996 guidelines– EU-15– Flanders (Belgium)

N2O flux modelling

Conclusions Future work

Long-term field experiments of Long-term field experiments of NN22O and NO fluxes from O and NO fluxes from agricultural soilsagricultural soils

Field set-up: spatial and Field set-up: spatial and temporal distributiontemporal distribution

•Selection of benchmark sites

different of agro-pedological

regions

different land use

intensive agriculture

•6 repetitions per field

•Event-directed monitoring

20-25 campaigns per year

•Monitoring during 2-3 years

Set-up for NSet-up for N22O flux measurements:O flux measurements:closed chamber and FAIDclosed chamber and FAID

from FAID

to FAID

pressure vent

Results: NResults: N22OO

-200

0

200

400

600

800

02 04 06 08 10 12 02

months (1998-1999)

g N

2O

-N h

a-1 d

-1

fertilization

Emission factor: NEmission factor: N22OO

Campaign 1997-2000 (> 400 data, 4 soil textures)

– N fertilisation: 75 – 506 kg N ha-1

– N2O-N emission: 0.3 – 31.7 kg N ha-1

– Average EF (95% interval): 5.3% (1.9-8.5%) of applied N

– Median EF: 4.5% of applied N

Campaign 1992-1995 (> 600 data, 1 soil texture)

– N fertilisation: 0 – 414 kg N ha-1

– N2O-N emission: 2.2 – 10.6 kg N ha-1

– Average EF (95% interval): 2.4% (0.9-3.9%) of applied N

– Median EF: 2.4% of applied N

Set-up for NO flux measurements:Set-up for NO flux measurements:open chamber and NOx analyseropen chamber and NOx analyser

inlet

outlet

Emission factor: NOEmission factor: NO

WFPS 50%– 0.3 – 1.7% of applied N

WFPS 90%– 1.1 – 7.1% of applied N

Effect on N2O-indirect}

-100

0

100

200

300

0 5 10 15 20 25

Days

ng N

O-N

m-2

s-1

60 kg N100 kg N

Controling factors for NControling factors for N22O and NO O and NO fluxesfluxes

Land-use and soil fertility grassland > arable land

N fertilisation type and application rate

Period of the year soil temperature and moisture

Assess the effect size of these factors

Inventories: IPCC 1996 guidelinesInventories: IPCC 1996 guidelines

NN22O from agriculture in EU-15O from agriculture in EU-15

4.93.2

6 5.17.3

14.2

10.7

7.4

2.9

5.9

3.62.4 2.5 1.7

5.6

0

4

8

12

16

kg N2O-N ha-1

0.50.4

1.2

0.3

0.5

0.1 0.10.2

0.40.5

0.3

0.8

0.4

0.9

0.5

0

0.4

0.8

1.2

ha capita-1

Average NAverage N22O emission from agricultureO emission from agriculture

4.2

1.2

0.9

0

1

2

3

4

5

6

7

kto

n N

2 O-N

N2O-direct N2O-indirect N2O-animals

6.3 kton N2O-N yr-1

Flanders: 1990-2000IPCC default EF, country specific activity data

13.1 12.7 12.4 12.6 12.6 12.7

0

5

10

15

20

25

1990 1992 1994 1996 1998 2000

Evolution NEvolution N22O from agricultureO from agriculture

kton N2O-N, EF = 1.25 kton N2O-N, EF = 3.4 (1.3 – 5.6)

Flanders: 1990-2000

6.6

6.4

6.3

6.4

6.3

6.4

6.3 6.3

6.4

6.5

6.31

6

6.5

7

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Uncertainty: 100%

Country specific activity dataCountry specific activity data

Country – specific data IPCC default data

106 kg N2O-N

N2O-direct 7.2 10.7

N2O-animals 0.9 1.5

N2O-indirect 4.4 5.8

N2O-total 12.4 18.0

Belgium: 1991 Uncertainty: 10% ?

• Country specific animal N excretion factors• Country specific dry matter contents of crop residues

Country specific activity dataCountry specific activity data

• Besides country specific animal numbers, fertilizer application and crop yields use country (region) specific:

• animal N excretion factors• dry matter contents of crop residues

• NO and NH3 emission

• NO3- leaching

NN22O emission modellingO emission modelling

Arable land: empirical model Arable land: empirical model Parton Parton et al.et al. (1996) (1996)

0

100

200

300

400

500

600

700

800

11/03/1997 19/06/1997 27/09/1997 05/01/1998 15/04/1998 24/07/1998 01/11/1998 09/02/1999

Date

N2O

flux

(g

ha-1

d-1

) MeasuredModel

ConclusionsConclusions

N2O emission factor: 3.4% (1.3-5.6%) / 3.0%

– Underestimation of N2O from agriculture in Flanders ?

NO emission factor: 0.3 – 7.1%– Agriculture is a significant NO source (more research !)

EF development:– Attention to spatial and temporal resolution, uncertainty

National inventories:– Use country specific activity data to reduce inventory uncertainty

Modelling:– Underestimation for intensive agriculture

Future workFuture work

Future workFuture work on N on N22O (and NO)O (and NO)

Meta-analysis: statistical tool to compare different independent field experiments to assess the effect size (Hedge ’s index, d) of controlling factors for N2O (and NO) emission

– Fertiliser N application rate, climate (soil temperature and moisture), soil fertility (C&N-content), texture, drainage and pH

Use ‘d’ in empirical modelling

Uncertainty assessment via Monte Carlo analysis

Link with C sequestration (e.g. effect of no-tillage)