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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)
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