Air quality - ammonia

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Ammonia is released to the atmosphere from livestock urine and excreta as well as from manufactured fertilisers such as ammonium nitrate and urea. Ammonia in the atmosphere causes acidification of rain (acid rain) and can react with atmospheric sulphur dioxide to form fine particulates (PM10 and PM2.5) which are harmful to health.

The UK is committed to reducing its ammonia emissions and in 1999 signed up to the Gothenburg Protocol to abate acidification, eutrophication and ground level ozone. In addition, the National Emissions Ceilings Directive sets ceilings for each European Member State for emissions of ammonia, oxides of nitrogen, sulphur dioxide and volatile organic compounds (VOCs). These four pollutants are primarily responsible for acidification, eutrophication and ground-level ozone.

The revised Directive is being developed with the aim of reducing ammonia in the environment, including agricultural systems. It will include reduction targets for 2020 and 2030. The Government is assessing how these are to be delivered. It is anticipated that farmers will have to adopt low-emissions technologies.

Reducing ammonia losses

Livestock farmers can reduce ammonia losses through good practice in the following areas: diet formulation, ventilation including scrubbers and bio filters, slurry cooling and/or acidification, slurry storage and manure spreading techniques. Further information on options for ammonia mitigation can be found here.

For the latest information about this project, visit the AHDB website

Establishing ammonia emission factors for straw-based finishing pig buildings and evaluating improved ventilation systems

We have been measuring the ammonia emissions from different pig buildings in order to help update emission factors. One straw-based and one fully slatted finisher farm were used for the trial.

The ammonia concentration in the inlet and exhaust air was measured, using the ammonia analyser developed by AHDB in conjunction with Harper Adams. In addition, the number of pigs, weights, feed intake, protein content of diets, ventilation rates, external and internal temperature and relative humidity were also recorded, as per the internationally recognised VERA protocol, which is the first to standardise how measurements are taken and results presented. This allows results from different studies to be compared and systems benchmarked.

The results, expressed in kilograms of ammonia per animal place, per year (kgNH3/AP/year) indicate that current commercial performance is much better than the current EFs, and results (mean) are:

Finishers on slats: 1.72kgNH3/AP/year, vs EA EF 3.1kgNH3/AP/year

Finishers on straw: 1.22kgNH3/AP/year, vs EA EF 2.97kgNH3/AP/year

Due to the positive outcome of these trials, AHDB is working on an accelerated programme of monitoring so the industry can work from a better base.

Summary: Establishing ammonia emission factors for shallow pit, fully-slatted finisher buildings

Summary: Establishing ammonia emission factors for straw-based buildings

AHDB Pork ammonia sensor

AHDB Pork has developed an ammonia sensor with Harper Adams University for use on pig farms, to assess the performance and environmental impact of new buildings and/or feeding regimes.

It is anticipated that this will be used to establish current levels of ammonia emissions from modern buildings and to confirm appropriate emissions factors. Click here for details of this project.

Permitted farms

Permitted farms have to apply production systems which are proven to reduce emissions of ammonia to the atmosphere. These are detailed in the European Commission’sBest Available Techniques (BAT) Reference document (BREF) which describes management practices, housing systems and techniques that minimise emissions and environmental impact. These have to be employed when planning new pig housing and slurry storage facilities on permitted installations. 

More information:

Environment Agency document: How to Comply with Your Environmental Permit for Intensive Agriculture, please AHDB Pork guidance on permitted agriculture.


Tried and Tested

Tried and Tested aims to help farmers to improve nutrient management planning through a toolkit of practical nutrient, manure and feed planning guidance.