Ammonia emissions from UK agriculture – the NARSES model

TFEIP Workshop, Thessaloniki, Greece, 30-31 October 2006

Tom Misselbrook

IGER, North Wyke, UK

Imperial College

Introduction

• Inventory model for a major emission source - NARSES as an example

• Detailed partial emission factors (incl. process-based)

• Detailed activity data

• Spatial and temporal disaggregation

• Introduction of abatement measures

• Cost curve development

• Mapped output

NARSES

• National Ammonia Reduction Strategy Evaluation System

• Ammonia emissions from UK agriculture >80% total UK emission

• Replaces ‘old-style’ UK ammonia emissions inventory

• Nitrogen flow model, mass-conservative

• EF now expressed as % of available N rather than ‘fixed’ units

Ammonia sources

1. Nitrogen fertiliser applications

NH3

Emission = fn (fertiliser type, land use, temperature, rainfall, soil pH)

Monthly time-step

Fertiliser types associated with different potential emissions

Activity data from British Survey of Fertiliser Practice

EF

Ammonia sources

2. Nitrogen excretion by livestock

NH3

Total N

(RAN)

NH3

NH3NH3

NH3

grazing

yards

housing storage spreading

measures

Emission factors

Livestock group

grazing yards housing - slurry

housing – straw-bed

Slurry store

lagoon FYM heap

…

Dairy cow 6% 75% 30% 25% 5% 50% 35%

Dairy heifer

Beef cow

Beef heifer

Bull

Cattle 1-2 yrs

Calves

Sows

….

All expressed as % RAN in the emission pool

Activity data

Data sources:

• June agricultural census (livestock numbers)

• Farm practice surveys

• Ad-hoc surveys

• Expert opinion

Technical measures

For each potential abatement technique:

Emission reduction efficiency

Applicability

Current implementation

Cost

e.g. shallow injection

70%

80%?

1%

£2.40 per m3 slurry

NARSES Model : 8 Sectors, 269 Nodes, 349 Links, 162 Measures

Operates at 10 x 10 km grid

Cost-curve optimisation

Model developments

• Increasingly link EF to environmental and management variables

• Include links with N2O emission and NO3 leaching models

• Include ‘front-end’ linking diet with N excretion

Projections

NARSES a robust model for making projections:

• Defines key parameters which need to be surveyed/estimated

• Accounts for bulk changes in livestock numbers

• Also accounts for management changes – policy, environment or market forces

0

20

40

60

80

100

1990 1995 2000 2005 2010 2015 2020

kt N

H3

old-style inventory

NARSES

Projections – Dairy cows

UK milk production to stay the same

Cow numbers declining, increasing milk yield per cow

Increasing N excretion per cow

0

10

20

30

40

Pigs Poultry

kt N

H3

2005

2020

Projections – Pigs and poultry

Implementation of IPPC

[No change in livestock numbers]

Summary

To make robust projections:

• Sufficient level of detail within model

• EF linked to environmental and management variables

• Ability to gather activity data at sufficient level

• Ability to predict changes in key management and environmental variables

THANK YOU!