Ammonia mitigation measures at CAFRE Beef and Sheep farms

June 9, 2025

The CAFRE Lowland Beef and Sheep Centre and the CAFRE Hill Farm are managed as demonstration platforms for both students and farmers, illustrating best practice. 

The Beef and Sheep Centre comprises 130 hectares of mainly grassland, carrying approximately 100 suckler cows and 270 breeding ewes with all offspring finished on farm. 

The Hill Farm Centre comprising 960 hectares, carries 100 suckler cows and approximately 1300 breeding ewes, with all beef and most lambs finished at the Beef and Sheep Centre. 

The enterprises at both farms have been modelled for ammonia emissions, using the National Ammonia Reduction Strategy Evaluation System (NARSES). This allows the flow of total nitrogen and total ammoniacal nitrogen to be quantified and ammonia mitigation measures to be assessed. Data from the 2022 calendar year was used to establish a baseline for the farms. Different ‘what ifs’ in the model can be assessed in terms of benefits/impacts on ammonia emissions for each enterprise.

Ammonia mitigation measures in place for cattle

• All slurry is applied using LESSE.
• All inorganic fertiliser applied is in the form of stabilised urea.
• Comfort slat mats are used in two thirds of slatted accommodation at The Beef and Sheep Centre.
• One new above ground slurry store has an impermeable cover. The three other above ground stores have had lightweight expanded clay aggregate (LECA) applied in January 2025 to reduce ammonia emissions from these stores.
• 20 suckler cows at the Hill Farm are outwintered to improve habitat for breeding waders. This has reduced silage demand, slurry storage and spreading.
• Extended grazing is practiced when possible.

The graph highlights ammonia emission sources for all the beef cattle at CAFRE in 2022.

• Housing, manure storage and spreading account for 70% of the total ammonia emissions.
• Using LESSE reduces ammonia emissions by approximately 30%.
• Replacing urea with stabilised urea decreases emissions by 15%.
• In best case scenario, where all floors are low emission, e.g. comfort slat mat and lower protein diets are matched to stock requirements, emissions can be further reduced by 14% over the current baseline.

Sheep

The ammonia emissions associated with the two flocks are outlined in the table below.  The big difference between the two flocks is that 80% of the Hill Farm flock is housed for about three months, whereas the lowland flock is not housed. There are limited further mitigation options available as most of the emissions are associated with grazing and stabilised urea is already used. Housing of the hill flock and associated manure handling is associated with 43% of the total ammonia emissions, however, given the area of in bye land and the climatic conditions, housing of this flock is essential.

	Lowland Farm	Hill Farm
Grazing/outdoor	72%	53%
Housing	0%	18%
Manure storage	0%	9%
Manure spreading	0%	15%
Nitrogen fertilisers	28%	4%

Summary

In summary, it has been established at CAFRE that beef and sheep enterprises can reduce their ammonia emissions through changes in management such as:

• Using LESSE.
• Making use of stabilised urea.
• Covering above ground slurry stores.
• Extending the grazing season.

For further information visit the Business Support area.