Reducing ammonia emissions from agriculture

The techniques below are recognised techniques for the reduction of ammonia. The amount of reduction you can expect will be unique to your operation and will depend on how you manage the techniques.

The figures below are an indication of the reduction you can apply to calculation of ammonia releases but this will depend on what emission factor you have used and what type of housing you propose.  


Scrubbers can reduce the ammonia in channelled emissions of air by up to 99% but depending on the housing type this may not always be achievable. The correct sizing of the scrubbers is vital to achieve the appropriate reduction.

Find further guidance on scrubbers on our Ammonia scrubber design and use page. The technology specified in applications must be the same as those that are ultimately built. 

Manure drying 

The appropriate emission factors for common manure drying techniques for pigs and poultry are available on the Emission factor pages. Manure drying for cattle housing is not currently practicable but if the technology and housing types change, then it is likely that similar reductions in ammonia emission to poultry and pigs are possible. This only applies to drying of manure in situ, subsequent drying when the manure is removed is likely to require a permit. 

Manure store covers 

The appropriate emission factors for pigs, poultry and cattle are listed in our emission factor pages. Novel techniques not listed will need to be evaluated individually.  

Frequent manure removal 

The appropriate emission factors for pigs and poultry are listed in our emission factor pages. Novel techniques not listed will need to be evaluated individually. Frequent scrapping of cattle sheds is not always practical and can result in animal health issues due to cattle falling. However proper design of cattle sheds with sloped floors to aid scrapping at 1.5 to 2 hour intervals can achieve significant reduction in ammonia emissions, this option may be practicable in areas where background ammonia levels are high. 

Heat exchangers 

An ammonia reduction factor of 35% can be applied to broilers and 15-20% to layer housing. 

Acidification of manure 

Acidification of manure to achieve a pH of <5.5 will result in a reduction in ammonia from housing, storage and spreading, ranging from 50 to 80%. The precise reduction to be applied will need to be on a site specific basis and depend on livestock and housing type. The over acidification of soil can lead to other issues and therefore the subsequent use of the manure must be considered. Lower pH soils can lead to increased Nitrous Oxide releases. 

Novel techniques to control ammonia 

Novel techniques to reduce ammonia emissions are emerging and are welcomed by NRW. We will endeavour to establish the appropriate emission factor or % reduction associated with each technique for use in modelling the impact of the development. 

Evidence of ammonia reduction

For us to take into account the reduction in ammonia by using the novel techniques, the following evidentiary criteria will need to be established: 

  • Ideally a control operation with the same parameters, is monitored at the same time as the novel technique  
  • The measurement methodology must be appropriate 
  • Intermittent measurements can be used for mature livestock, provided there is a minimum of four measurement periods during the course of a year and information on factors such as ventilation rate, diet and performance are obtained. 
  • In buildings where livestock are growing and more than one growth cycle may occur over the year, measurements must be repeated for each of the growing cycles in the year. 
  • The measurement technique must be recognised and backed by peer review  
  • Emission measurement data must be properly recorded and traceable and available for the calculations to be checked. 
  • The operator must adopt a suitable QA/QC approach in accordance with guidance, to enable their results to be validated 
  • There must be a plausible reason for the new emission estimate being outside the expected range. 
  • For sites requiring a permit we will include monitoring requirements to establish if the designed abatement is suitable and performing as designed. 
Last updated