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An ammonia monitoring trial has saved pig producers an estimated £15.3m by reducing greenhouse gas emissions. Ammonia trial cuts emissions and saves sector £15.3m

An ammonia monitoring trial has saved pig producers an estimated £15.3m by reducing greenhouse gas emissions.

The savings have been made because results from the Agriculture and Horticulture Development Board initiative have enabled the industry to firmly demonstrate compliance and best practice, saving it from environmental mitigation costs.

Pig producers must meet the Best Available Technique (BAT) Associated Emission Levels (AELs). If they cannot prove they are doing so, they must upgrade and pay mitigation costs.

The AHDB says the trial has provided welcome proof of lower emissions and allows for updates in regulating the sector through accurate annual pollution inventory reporting and future habitat risk assessments.

The trial has provided a comprehensive and valuable study of ammonia emissions from different pig production systems, improved the industry’s understanding of emissions from the pork sector and demonstrated the reduction in emissions.

The aim of the trial programme was to understand more about ammonia emissions from modern pig production, involving eight representative types of pig housing system, with each one monitored continuously for at least a year. 

AHDB knowledge transfer manager Zanita Markham said: “We are delighted to be able to present the most comprehensive and recent study of its kind. It demonstrates compliance on all housing types, which is to the industry’s credit.

“Importantly, it also sets a benchmark against which we can measure further reductions in emissions in the future. The results also demonstrate that farmers have decreased ammonia emissions since the historic data was first published.”

Until this trial, the Environment Agency used emission factors based on national atmospheric emissions data data. But, not all these figures met the BAT standards for pig housing.

Different systems

The Environment Agency is now using results from the trial to inform new emission factors – a value which estimates the amount of greenhouse gas emissions associated with different pig production systems.

For example, the new ammonia emission factor for weaners on slats is 0.5kg of ammonia per animal place per year – significantly lower than UK National Atmospheric Emissions Inventory (NAEI) figure of 0.9kg which was used until now.

Similarly, the revised figure for finishers on slats is 2.5 kg of ammonia per animal place per year compared with the previous figure of 4.1 kg and, for finishers on straw, it is now 2.1 kg compared with 3.6 kg previously. 

Natural England is also using the emission factors as part of planning applications. The report and findings are available for Defra to use for annual reporting for international air quality obligations.

An Environment Agency spokesperson said: “We are really pleased to have worked with AHDB to provide evidence that will continue to support permitting decisions for the industry for many years to come.”

AHDB senior environment scientist Harley Stoddart said the project
had demonstrated the benefits of
collaboration by providing robust
evidence of ammonia emissions from a wide range of modern pig production systems.

As well as Defra and the Environment Agency, the trial involved a number of pig producers. Ms Markham added: “We would like to extend our gratitude to all the farmers who participated in this study.”

More details about the results and implications can be found in the Knowledge Library on the AHDB website at Producers with questions can email