Bangor University research examines nitrogen efficiency from controlled-release fertilizers

Masters by Research student Elin Thompson is investigating the nitrogen-use efficiency of controlled-release fertilizers (CRFs) in turfgrass.

The independent research project, funded by ICL, compares coated fertilizers with conventional nutrition across a series of controlled experiments. The aim is to generate data on how different fertilizer approaches affect nitrogen availability, potential nutrient losses and turf growth over time.

What the research is measuring

The study is looking at several routes through which applied nitrogen can either be taken up by turf or lost from the system.

Elin’s experiments include:

• Ammonia emissions — measuring nitrogen losses as ammonia following fertilizer application.
• Leaching — collecting drainage water from individual turf units and analyzing ammonium and nitrate losses.
• Nitrous oxide emissions — measuring gaseous losses following fertilizer application using sealed growth chambers.
• Biomass production — assessing turf growth and nitrogen uptake over time.
• Turf quality — monitoring chlorophyll levels as an indicator of turf color and condition.

Together, these measurements allow fertilizer performance to be assessed beyond visual turf response alone.

Elin applies fertilizer treatments to turf cores used in the ammonia-emission experiment.

Comparing controlled-release and conventional nutrition

Controlled-release fertilizers use coatings to regulate the release of nutrients over time. The Bangor University study is testing whether this controlled nutrient supply can improve nitrogen-use efficiency while reducing losses compared with conventional fertilizer treatments.

Rather than assuming that a slower nutrient release automatically produces a better environmental outcome, the project measures the different pathways directly.

That includes nitrogen remaining available to the turf, nitrogen recovered in plant biomass and nitrogen lost through leaching or gaseous emissions.

Elin explained that the objective is to provide evidence that can help turf professionals make better-informed fertilizer choices.

“I hope to demonstrate better nitrogen efficiency and establish how long a single controlled-release fertilizer application can sustain turf growth.”

Independent research with industry support

ICL is funding the project and has supplied the fertilizers used in the experiments, while Bangor University retains responsibility for the scientific design, methodology and analysis.

For Dr Andy Owen, International Technical Manager at ICL, that independence is an important part of the collaboration.

“Working with universities gives us access to independent, scientifically rigorous research that can test how our products perform under controlled conditions. It also helps build a stronger evidence base around fertilizer efficiency and nutrient losses.”

Biomass is collected from each treatment to measure turf growth and assess differences between fertilizer programs.

Building a clearer picture of fertilizer efficiency

The project is designed to look at fertilizer efficiency as a balance between turf response, nutrient uptake and potential nitrogen losses.

That matters because fertilizer performance cannot be judged from turf color or growth alone. Two treatments may produce a similar visual response while differing significantly in how efficiently applied nitrogen is used.

By measuring ammonia, nitrate leaching, nitrous oxide emissions, biomass and turf quality within the same research program, the study should provide a more complete view of how controlled-release fertilizers behave under the test conditions.

The results will help inform future work on fertilizer selection and nitrogen-use efficiency in managed turf.