1. Challenges and opportunities
for nitrogen emission
reduction strategies
Mark Sutton and Oene Oenema
(co-chairs TFRN)
Air Science Policy Forum 15 April 2013, Dublin
www.clrtap-tfrn.org

2. Nitrogen oxides
(NOx)
Nitrous Oxide
(N2O)
Ammonia
(NH3)
Leached Nitrate
(NO3
-)
Further emission
of NOx & N2O
carrying on
the cascade
Natural ecosystems
Ammonium nitrate
in rain (NH4NO3)
Nitrate in streams,
groundwater &
coastal seas
High temperature
combustion
& industry
Nr
Livestock farming
for food
Nr in
manure
Eventual
denitrification
to N2
Simplified view of the Nitrogen Cascade
Unintended
N flows
N form in
the cascade
Terrestrial
Eutrophication
Freshwater Eutrophication
Greenhouse
gas balance
Particulate
Matter
Tropospheric
ozone
formation
Stratospheric
ozone loss
Soil acidification
Urban air
quality
Marine Eutrophication
Environmental
concern from Nr
Sutton et al. (2011 ENA)
Fertilizer
manufacture
Crops for food &
animal feed
Crop biological
nitrogen fixation
Intended
N flow

3. Challenges & Opportunities
Challenges
• Nitrogen flows are interlinked: Need to avoid pollution
swapping
• Much of the problem is related to agriculture, especially
livestock (80% harvested N to animals)
Opportunities
• Nitrogen flows are interlinked: Opportunity for synergy in
reducing multiple impacts
• Opportunity to improve Nitrogen Use Efficiency
• Many mitigation opportunities in agriculture still available!

4. Nitrogen biodiversity and carbon sequestration
Moninea Bog, Natura 2000 Site, Northern Ireland

5. 

6. Bog moss
Sphagnum imbricatum




7. Threats to ecosystem services
and recovery prospects
• Timescales of recovery vary substantially
• Fast recovery possible (order 10 years)
– Epiphytic biodiversity
– Heathland (with active restoration)
• Slow recovery (several decades)
– Forest ground flora (dynamic models…)
– Peatland carbon sequestration…

8. Summary of N flows in Europe
Human
nutrit.
agricult
soils
Livestock
farming
Atmospheric N2 pool
Crop
production
Atm
depos
17.6
7.1
11.8
1.5
2.1
4.5
2.3
1.0
3.1
Net import of
food & feed
2Crop
N2fix
Fertilizers
11.2
3.8
NH3,NOx
& N2O
emission
Denitrifi-
cation
N2 fix
indust
& traffic
3.4
Europe (EU27), around 2000. N fluxes in TgN/yr
Export by
rivers to
the sea
Net atmosph.
export
9.3
2.4
3.5
6.84
6
13.8
0.4
4.7
5.8
3.7
0.8
3.2
0.1
Semi-nat.
soils
Nat
N2fix
Wood
exp.
Atmospheric NH3,NOx, N2O
wwt
Leaching
& runoff
0.3
2.41.4
0.2
3.8
0.2
0.2
4.7
6
4
3
2
1
5
7
ENA, 2011

9. Agriculture
1. Improving nitrogen use efficiency in crop production
2. Improving nitrogen use efficiency in animal production
3. Increasing the fertilizer N equivalence value of animal manure
Transport and Industry
4. Low-emission combustion and energy-efficient systems
Waste water treatment
5. Recycling nitrogen (and phosphorus) from waste water systems
Societal consumption patterns
6. Energy and transport saving
7. Lowering the human consumption of animal protein
Seven key actions for better
nitrogen management
ENA, 2011 and Nature 14 April 2011
The Way Forward:
More efficient N use saves farmers money
reducing nitrogen air pollution,
while being needed to meet Parties’
commitments for climate and water pollution

10. Short-term needs
- Updating of the Ammonia Guidance Document
- Options for the revision of Annex IX on Ammonia
Long-term needs
- Development of integrated perspective on nitrogen
- European Nitrogen Assessment
- New Guidance Document on Nitrogen Budgets
- Nitrogen and the Green Economy
Task Force on Reactive Nitrogen
contributions to UNECE CLRTAP

11.  Targets
 Emissions reduction targets (% decrease from reference)
 Thresholds
 Farm size (EU: 72% cattle on 13% farms),
 Tanker size for manure spreading (IE: 60% with >10 m3)
Annex IX measures:
ambition levels and thresholds

12. Overview of costs of ammonia
abatement measures
Measures Cost, €/kg NH3-N saved
Nitrogen management -1.0 to 1.0
Feeding strategies -0.5 to 1.0
Animal housing 0.0 to 10.0
Covering slurry storages 0.1 to 4.0
Slurry application -0.5 to 3.0
Urea application -0.1 to 4.0

13. 5 top priorities
for ammonia mitigation
1. Low-emission land application of manure & fertilizer:
a) Application of cattle, pig & poultry slurry & solid manure
b) Low emission use of urea fertilizer (ban is not proposed)
2. Animal feeding strategies to reduce N excretion, from
cattle, pig & poultry.
3. Low-emission techniques for all new manure stores for
cattle and pig slurries and poultry manure.
4. Strategies to improve N use efficiencies and reduce N
surpluses, with N balances on demonstration farms,
5. Low-emission techniques in new and largely rebuilt pig
& poultry housing.

14. Slurry spreading:
a wide range of low-emission
techniques are available
The car and the exhaust pipe…
Splash Plate Spreader
- 1950s technology
Trailing Shoe Slot Injector
Trailing Hose

15. EU benefit-cost ratios for
NH3 and NOx mitigation
Van Grinsven et al. (2013, ES&T in press)
NH3
NOx

16. Concluding remarks
 Low-cost nitrogen mitigation must increasingly
focus on ammonia.
 The options have been described in detail in
the draft Annex IX and the UNECE Guidance
Document.
 Ammonia abatement is part of improving
Nitrogen Use Efficiency, helping meet climate
& water pollution targets, with significant
economic benefits.