improving the uk agricultural n o inventory...improving the uk agricultural n 2 o inventory (inven 2...
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Improving the UK Agricultural N2O
inventory (InveN2Ory project)
Chris Adams [email protected] www.wensumalliance.org.uk
Chris Adams
Kevin Hiscock, Faye Outram
Dave Chadwick, Julian Andrews
Content • Background
– Current GHG inventory methodology
– Trends in Emissions
– Why we need to change our approach
• Nitrous Oxide: Sources + sinks
• Components of the new InveN2Ory project
– Direct Emissions
– Indirect Emissions and the DTC projects
• Preliminary Results
• Current and future work
www.wensumalliance.org.uk
Current UK agriculture N2O inventory methodology
• Essentially Tier 1
• Using year 1996 Guidelines, 2000 Good Practice Guidance
– IPCC standard Emission Factors (EFs)
– UK activity data
• livestock numbers
• fertiliser N use
• N excretion values
• Manure management systems
www.wensumalliance.org.uk
Trends in GHG emissions from UK agriculture
• Driven by change in stock numbers and fertiliser use
• Insensitive to farm system management and efficiencies
• Insensitive to adoption of abatement strategies
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Why change to a Tier 2 approach? • Tier 1 is a blunt reporting tool
• UK set challenging targets
• Industry GHG roadmaps
• Need a reporting tool that better reflects: – Soil types
– Rainfall zones
– Management of nitrogen sources
– Specific mitigation strategies
• Apportion uncertainty to specific parts of the inventory www.wensumalliance.org.uk
The InveN2Ory project: improving the UK agricultural GHG inventory (nitrous oxide)
InveN2Ory - Aims
• To generate an improved N2O inventory that reflects the range of soil types, climate and N sources of UK agricultural systems
– To generate Tier 2 (and potentially Tier 3) emission factors through measurements and modelling
– To verify emission factors and inventory totals and test appropriate cost-effective mitigation methods.
• To quantify uncertainty of the improved N2O inventory, and ascribe to the different stages of inventory building
Generate an improved inventory for reporting and methodology to
track changes in N2O emissions against the challenging reductions
that have been set
• Direct N2O emissions (from soils)
– Soil type, soil wetness
– N form: urine, dung, manure type, fertiliser N types
– Rate of N application
– Timing of N application (RB209 +
• Country specific activity data (spatial/temporal)
• Indirect N2O emissions (drainage, rivers & groundwater)
– Country specific fracleach values
– Country specific N deposition
www.wensumalliance.org.uk
Components of the new InveN2Ory project
NH3 (g)
NH4+
Org-N
NO2-
NO3-
N2 (g)
N2O (g)
Crop Uptake
Fertiliser Grazing returns
Nitrogen fixation
Atmospheric deposition
Denitrification
Direct Emissions
from soils
Direct Emissions
Experimental Platforms ( )
and Soil Typology
• Selection of sites and treatment combinations
• Standard experimental protocols
– treatments, plot size, chamber design,
chamber deployment, sampling method,
sampling frequency, GC testing,
data handling
• Identification of proxies
– Soil parameters (for modelling at field scale)
• Modelling
Standard Experimental Protocols
Direct N2O emissions:
•static chambers (40 x 40 x 30 cm)
•5 chambers per plot (stackable)
•3 replicate plots per treatment
•Plots are zoned
•Up to 11 treatments per experiment
(up to 165 chambers per experiment)
•Chambers must be installed at least 24
hours before sampling
•Chambers remain in same position
Emission factor measurements Tillage land:
N fertiliser (45) (Gilchristan, Rosemaund,
Woburn)
Control
AN rate 1 (RB209 timings)
AN rate 2 (RB209 timings)
AN rate 3 (RB209 timings)
AN rate 4 (RB209 recommended rate, RB209 timings)
AN rate 5 (> RB209 rate, RB209 timings)
AN rate 4 (RB209 timings) + DCD
Urea at rate 4 (RB209 timings)
Urea at rate 4 + DCD
AN at rate 4 (5 splits instead of 3)
Livestock manure (7) (Rosemaund,
Wensum, Gilchristan)
Control
FYM Autumn
Poultry litter autumn
Poultry litter spring
Layer manure autumn
Layer manure spring
Slurry surface broadcast - autumn
Slurry trailing shoe – autumn
Slurry surface broadcast – spring
Slurry trailing shoe - spring
Fertiliser N rate vs N2O flux – arable
Site 2
y = 0.0089x + 1.0425
R2 = 0.92
Site 3
y = 0.02x + 2.5783
R2 = 0.82
0
1
2
3
4
5
6
7
8
0 100 200 300 400
Application rate (kg N ha-1
)
Cu
mu
lati
ve N
2O
(kg
N2O
-N h
a-1
)
Site 1 Site 2 Site 3
Site 1
y = 0.707 +
0.145 (1.00994x)
R2 = 0.95
Source: Project AC0101
WP2: Emission factor measurements
Grassland: N fertiliser (24)
(Hillsborough, Crichton, Pwllpeiran, Drayton, North Wyke)
1. Control
2. AN* 70 (RB209 timings)
3. AN* 140 (RB209 timings)
4. AN* 210 (RB209 timings)
5. AN* 280 (RB209 timings)
6. AN* 350 (RB209 timings)
7. AN* 210 (RB209 timings) + DCD
8. Urea 210 (RB209 timings)
9. Urea 210 (RB209 timings) + DCD
10 . AN* 280 (3 splits 1st cut, 2 splits 2nd and 3rd cut)
* N Ireland will use
CAN
Non-linearity of N2O emissions from fertilised grazed grassland
Year 1
Year 2
Agriculture, Ecosystems & Environment
Volume 136, Issues 3–4, 15 March 2010, Pages 218–
226
Non-linearity of N2O emissions from fertilised grazed grassland
Year 1
Year 2
Agriculture, Ecosystems & Environment
Volume 136, Issues 3–4, 15 March 2010, Pages 218–
226
NH3 (g)
NH4+
Org-N
NO2-
NO3-
N2 (g)
N2O (g)
Crop Uptake
Fertiliser Grazing returns
Nitrogen fixation
Atmospheric deposition
Denitrification
Direct Emissions
from soils
Indirect Emissions
Non-linearity of N2O emissions from fertilised grazed grassland
Year 1
Year 2
Agriculture, Ecosystems & Environment
Volume 136, Issues 3–4, 15 March 2010, Pages 218–
226
NH3 (g)
NH4+
Org-N
NO2-
NO3-
N2 (g)
N2O (g)
Crop Uptake
Fertiliser Grazing returns
Nitrogen fixation
Atmospheric deposition
Denitrification
Direct Emissions
from soils
Indirect Emissions
NH4+
NO2-
NO3-
N2O
NH3 (g)
NH4+
Org-N
NO2-
NO3-
N2 (g)
N2O (g)
Crop Uptake
Fertiliser Grazing returns
Nitrogen fixation
Atmospheric deposition
N2O
Denitrification
Direct Emissions
from soils
Indirect Emissions
NH4+
NO2-
NO3-
N2O
NH3 (g)
NH4+
Org-N
NO2-
NO3-
N2 (g)
N2O (g)
Crop Uptake
Fertiliser Grazing returns
Nitrogen fixation
Atmospheric deposition
N2O
Denitrification
Direct Emissions
from soils
Indirect Emissions
Indirect Emissions
NH4+
NO2-
NO3-
N2O
Indirect Emission factors
EF-5 groundwater, drainage, rivers, estuaries
• Method 1: Used by the IPCC
dissolved N2O / dissolved nitrate
Problems
NO3- can be reduced and utilised
N2O can be produced
consumed
degassed
Chris Adams [email protected] www.wensumalliance.org.uk
(current estimates)
• Applied nutrients
• % of applied nutrients leached
IPCC 2006 default value of 0.3 (0.1–0.8)
• % of leached nutrients converted to N2O
and lost to the atmosphere
Chris Adams [email protected] www.wensumalliance.org.uk
Indirect Emission factors
EF-5 groundwater, drainage, rivers, estuaries
• Method 2:
(current estimates)
Indirect Emissions • Work within the Defra Demonstration Test Catchment
(DTC) research platform to improve indirect EFs of N2O
Avon (Hampshire) Mixed lowland farming
Consortium includes ADAS, University of Reading, University of Bristol, QMUL,
ENTEC and others...
Wensum (Norfolk)
Arable farming Consortium includes
University of east Anglia, Scott Wilson, Cranfield
University, British Geological Survey, Entec,
NIAB and others....
Eden (Cumbria) Livestock & mixed
farming Consortium includes Lancaster University, Newcastle University, Durham University,
University of Cumbria, Eden Rivers Trust, CEH
and others....
Catchment wide sampling Land use and sampling points in
the Wensum catchment
Catchment nitrous oxide vs. nitrate:
Feb 2011 – March 2012
High range of emission factors
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 2 4 6 8 10 12
N2O
N µ
g L-1
NO3- N mg L-1
Feb '11 March '11 April '11 June '11 July '11 Aug '11 Sept '11 Oct '11 Nov '11 Dec '11 Jan '12 Feb '12 March '12 Atmospheric Equilibrium
0
20
40
60
80
100
120
140
160
0 2 4 6 8 10 12 14 16 18 20
W12 W11 W21 W14 W15 W16 W17 W18 W13 W20 W05 W06 W01 W02 W03 W04 W07 W08 W09 W10
Chalk
Till
Feb Mar Apr May June July Aug Sep Oct Nov Dec Jan Feb Mar Apr May June
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Chalk
Till
16 months of catchment wide grab sampling in the Wensum (N2O and N species):
www.wensumalliance.org.uk
Improved indirect EF (Method 2)
• Applied N Land use, farm business survey data, general activity data
• % of nutrients leached Nutrient samples & EA flow
records
• % of leached nutrients converted to N2O and lost from the system
N2O measurements (air and water) gives both fluxes and EFs
Next steps
Summary: catchment wide sampling
• Gives significant improvements over current EFs and flux estimates
• BUT only covers a medium range of flow and drainage conditions
• Does NOT utilise the high resolution temporal data of the DTC projects
www.wensumalliance.org.uk
Wensum DTC mini-catchments
Sub-catchment sampling
● Nutrient and flow data: every 30 minutes
● N2O data at stations A-F: every week
● Hourly N2O data at A, B and E: every month
Sub-catchment sampling
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
400 500 600 700 800 900 1000 1100 1200 1300
A
B
E
Noon Dusk
Night
Minutes
µg
N2O
N L
-1
Diurnal patterns and in stream production of N2O
September 2011
Remaining Issues • N2O data not spatially robust due to uncertainty in in-
stream processes (N2O can be lost, used, produced or mixed)
www.wensumalliance.org.uk
Streams are not simply mixing but have multiple inputs along their courses
Remaining Issues • N2O data not spatially robust due to uncertainty in in-
stream processes (N2O can be lost, used, produced or mixed)
www.wensumalliance.org.uk
A
B
E
Limited
headwater
sampling
Field drains
Field drains
DTC mini sites
DTC high spec site
~300 m
Samples every 15-30 meters and at all main
field drains in DTC mini-catchments A, B and E
Remaining Issues
• N2O Measurements do not represent all flow conditions
• N2O data is IPCC compliant and at least as good as other studies but not as temporally robust as the high resolution nutrient data available from the DTCs
• Misses some key events
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Rain event
Rain event
Storm event
Rain event
Rain event
Storm event
Rain event
Rain event
Storm event
Solutions: What now?
• Increased sample capacity
• New equipment
• Increased temporal resolution
–Diurnal sampling
– Increased sampling rain and storm events at DTC sites and field drains
www.wensumalliance.org.uk
Final Points
• New GHG Inventory being assembled
• Tier 2 Inventory : UK data, UK farms, UK activity
• Track changes in N2O emissions due to changing practices and future mitigation measure
• Reductions in GHG not limited to the gases themselves but integral to agricultural nutrients cycles and practices
• Requires projects like the DTC to feed back nutrient data but also to fully understand our varying catchments
www.wensumalliance.org.uk
Emission factor Default value Uncertainty range
EF1 Direct emissions from
managed soils. 0.01 0.003 – 0.03
EF3 Direct emissions from
livestock urine and
manure deposited by
grazing animals.
0.02 0.007 – 0.06
EF5g Indirect emissions
from groundwater 0.002
EF5r Indirect emissions
from rivers 0.0075
(EF5 total)
0.0005 – 0.025
EF5e Indirect emissions
from estuaries
0.0025
IPCC emission factors for N2O
Source: IPCC (2006)
• Used by the IPCC to estimate N2O fluxes
• Relate N2O fluxes to the nitrogen in the system
General, not regional or
catchment specific
Nitrogen leaching rate calculation Period: 21/3/11 00:00 to 27/3/11 15:00 (= 6.625 days) Mean flow rate = 0.045 m3/s Mean nitrate concentration = 6.25 mg N/L Nitrate-N flux = 24.3 kg N/day Leaching rate for mini-catchments A and B (579.8 ha) = 15.3 kg N/ha/a (~7 – 8 % of applied N amount) Leaching factor of 0.07-0.08 much lower than the IPCC value of 0.3 (0.1-0.9)
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Example nitrous oxide flux and EF calculation Mean flow rate = 0.045 m3/s Dissolved N2O concentration = 1.06 µg N/L Dissolved N2O N flux = 0.004 kg N/day Emission factor for mini-catchments A and B : 0.004/24.3 = 0.00016 Lower than the IPCC value of 0.002
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