Combined innovations can deliver ammonia reduction of up to 54%, CAFRE research finds

Use of stabilised urea reduces ammonia emissions at the CAFRE Dairy Centre.

By Judith McCord, Senior Air Quality Technologist, CAFRE

The implementation of targeted ammonia mitigation technologies can cut emissions by more than half on Northern Ireland dairy farms, according to new research led by the College of Agriculture, Food and Rural Enterprise (CAFRE).

The study, which modelled emissions at the CAFRE Dairy Centre, demonstrates that integrating legislative and voluntary strategies can reduce ammonia emissions by up to 54%.

Ammonia, largely emitted through agricultural activities, poses significant environmental challenges, particularly to air quality and biodiversity. To combat this, CAFRE has adopted the National Ammonia Reduction Strategy Evaluation System (NARSES) to quantify nitrogen (N) flow and pinpoint emission hotspots across the dairy enterprise.

Judith McCord, Senior Air Quality Technologist at CAFRE, explained the methodology behind the initiative.

“Modelling of the CAFRE Dairy Centre inputs through the National Ammonia Reduction Strategy Evaluation System (NARSES) allowed the flow of total N and total amount of ammoniacal N (TAN) to be quantified,” she stated.

“The use of this farm ammonia modelling tool identified where ammonia is produced and how N is managed through the farm enterprise cycle.”

Real-World Application of Emission Modelling

CAFRE commissioned the Agri-Food and Biosciences Institute (AFBI) to carry out a comparative analysis of the CAFRE Dairy Centre, modelling scenarios with and without mitigation measures. The model incorporated data on herd structure and manure management across three livestock age groups: milking cows, dairy calves (0–1 year), and dairy replacements (1–2 years).

The mitigated scenario included a suite of practices:

• 100% use of stabilised urea (no calcium ammonium nitrate)

• 100% low emission slurry spreading equipment (LESSE)

Application of slurry using Low Emission Slurry Spreading Equipment (LESSE) reduces ammonia emissions on the CAFRE Farm Estates.

• A targeted and reduced crude protein diet (17%) for the milking herd

Judith McCord, Senior Technologist, CAFRE reports on the use of reduced and targeted crude protein diets for the dairy cattle at CAFRE.

• Low emission flooring and high-frequency scraping in housing areas

• Impermeable covers on all above-ground slurry stores

This integrated approach resulted in annual ammonia emissions of 3.54 tonnes.

Low emission flooring is in use within the CAFRE Dairy Centre to reduce the mixing of faeces and urine.

In contrast, the non-mitigated model—featuring splash plate slurry application, open slurry stores, higher protein diets, standard concrete flooring, and the use of CAN—resulted in emissions of 6.61 tonnes per year.

These findings revealed a stark difference in environmental impact. “This is a very encouraging result,” said McCord. “The use of ammonia reducing technologies on Northern Ireland farms will help the sector reduce ammonia emissions.”

Breakdown of Emission Reductions

The analysis highlighted that the primary contributors to ammonia emissions were housing (42% of total emissions in both scenarios) and manure handling. However, mitigation technologies significantly reduced emissions in these areas. For example:

• Low emission flooring and reduced protein diets cut housing emissions by 0.78 and 0.34 tonnes respectively.

• LESSE and impermeable slurry store covers delivered combined reductions of approximately 2 tonnes per year.

Above ground slurry stores are covered to reduce ammonia emissions at the CAFRE Dairy Centre.

• The use of protected (stabilised) urea further lowered the greenhouse gas output compared to conventional fertilisers.

Most Effective Mitigation Technologies

Based on the study’s findings, CAFRE identified the three most impactful ammonia reduction strategies for dairy farms:

1. 100% use of LESSE

2. Installation of low emission flooring with frequent scraping (every two hours) — offering an ammonia efficiency factor of 11kg NH₃

3. Reduction of crude protein in dairy cow diets by up to 2%

Judith McCord reinforced the importance of a holistic approach:

“Mitigation strategies that can be implemented at various stages of the system will help to reduce ammonia emissions. Demonstrated clearly at CAFRE – the efficient management of nitrogen can contribute to a reduction of ammonia emissions by up to 54%.”

Supporting Sustainable Farming Practices

CAFRE continues to drive research into innovative agricultural technologies that promote both environmental stewardship and farm profitability. These findings are already influencing best practices across the region through CAFRE’s Knowledge Transfer Programmes.

For further information on sustainable land management and ammonia reduction strategies, visit the CAFRE website.