Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Fully slatted floor
2.94
15.8
Solid floor (straw based system)
3.29
15.8
Partially slatted floor with reduced manure pit
2.06
15.8
Fully slatted floor with frequent slurry removal (a minimum of once weekly removal achieved through scraping, pumping or flushing)
2.21
15.8
Farrowers (including piglets)
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Fully slatted floor
4.62
15.8
Solid floor (straw based system)
5.41
15.8
Fully slatted floor or partially slatted floor (with a combination of water and manure channels)
3.23
15.8
Weaners (between 7kg and 30kg live weight)
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Fully slatted floor
0.443
21
Fully slatted floor with frequent slurry removal (a minimum of once weekly removal achieved through scraping, pumping or flushing)
0.332
21
Solid floor (straw based system)
0.254
21
Partially slatted floor with reduced manure pit
0.332
21
Production pigs (over 30kg live weight)
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Fully slatted floor
2.813
18
Fully slatted floor with frequent slurry removal (a minimum of once weekly removal achieved through scraping, pumping or flushing)
2.11
18
Solid floor (straw based system)
1.888
18
Partially slatted floor with reduced manure pit
2.11
18
Ammonia from pig slurry storage
Slurry store or lagoon cover type
Ammonia emission factor (kg ammonia per m2 per year)
Store or lagoon with no cover
1.13
Store or lagoon with a rigid cover
0.23
Store or lagoon with a floating cover
0.45
Store or lagoon with a low tech cover (such as a natural crust or straw cover)
0.68
Ammonia from pig manure storage
Manure storage
Ammonia emission factor (kg ammonia per tonne per year)
Manure heap
0.85
Ammonia emission factors for poultry
Broilers
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Indoor rearing
0.024
20.3
Free range rearing
0.03
20.3
Layers
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Enriched caged systems with belt removal
0.048
15.3
Non-caged system – single tier
0.137
15.3
Non-caged system – multi-tier with belt removal
0.073
15.3
Free range poultry
For typical free range systems, in a 24-hour period it is estimated that birds spend:
10% of time on the range
90% of time within the housing
The following table shows how the standard free range emission factors have been calculated for screening and modelling purposes. You should use the combined housing and ranging factors for pollution inventory reporting.
Emission factor for housing component (kg ammonia per animal place per year)
Emission factor for outdoor component (kg ammonia per animal place per year)
Emission factor based on a 90% housing and 10% ranging split (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Single tier free range layers
0.137
0.239
0.147
17
Multi-tier free range layers
0.073
0.239
0.090
17
Free range broilers
0.024
0.084
0.03
20.3
Adult breeders (layers)
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Single tier litter based system
0.133
16
Multi-tier rearing with litter removal twice per week
0.033
16
Multi-tier rearing with litter removal once per week and on-belt drying
0.02
16
Breeder rearing (pullets)
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Litter based system
0.043
16
Pullets
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Litter based system
0.043
15.9
Multi-tier rearing with litter removal twice per week
0.011
15.9
Multi-tier rearing with litter removal once per week and on-belt drying
0.006
15.9
Enriched cages with belt removal
0.028
15.9
Turkeys
Housing type
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Male
0.646
21.2
Female
0.452
21.2
Ducks
Housing system
Ammonia emission factor (kg ammonia per animal place per year)
Crude protein content of animal diet (%)
Fully or partially slatted floor
0.151
22
Litter
0.151
22
Ammonia from poultry manure storage
Manure or litter type
Emission factor (kg ammonia per tonne per year)
Laying hen manure
2.68
Other poultry litter
1.12
Adjusting emission factors
If you operate a housing system not listed in this guide, you may need to give evidence of a site-specific ammonia emission factor as part of your permit application.
It is also possible to adjust these emission factors in scenarios where you use:
a lower crude protein content in the animal’s diet
other ammonia mitigation measures
an occupancy rate significantly lower than the standard rate
For more information on emission factors
These emission factors figures are based on best available information. You can get a copy of the report that informs this guide from your Environment Agency permitting officer or site officer if you need more information on:
adjusting the standard emission factors
calculating site-specific emission factors
Updates to this page
Published 29 November 2024
Last updated 4 December 2024
+ show all updates
Moved the information about free range poultry into its own section.