Use these emission factors for:
This guidance supports the intensive farming risk assessment for your environmental permit guide.
Ammonia emission factors for pigs
Sows (including gilts)
| Housing type |
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 scrapping, 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 scrapping, 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 scrapping, 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 system – single tier |
0.147 |
17 |
| Free range system – multi-tier |
0.090 |
17 |
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 free range emission factors listed in the previous table are based on these proportions.
The following table shows how these free range emission factors have been calculated for screening and modelling purposes.
|
Emission factor for housing component based on animals being housed for 100% of the time (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) |
| Single tier free range layers |
0.137 |
0.239 |
0.147 |
| Multi-tier free range layers |
0.073 |
0.239 |
0.090 |
| Free range broilers |
0.024 |
0.084 |
0.03 |
Adult breeders
| 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