Ammonia emission factors for pig and poultry screening, modelling and reporting

Use these emission factors for:

• carrying out ammonia assessments as part of your intensive farming permit application
• calculating your annual emissions for reporting to the pollution inventory

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,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 scrapping,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 scrapping,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 system – single tier	0.147	17
Free range system – multi-tier	0.090	17

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 free range emission factors listed in the previous table are based on these proportions.

The following table shows how thesethe 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 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)	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