Sheep urine study examines impact of greenhouse gas

Posted by er134 at Nov 26, 2015 12:15 PM |
New research project will examine pollution levels from nitrous oxide - commonly known as ‘laughing gas’ and is currently used both in anaesthetics and as a ‘legal high’

Issued by University of Leicester Press Office on 26 November 2015

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A new sheep urine research project will examine pollution levels from nitrous oxide - commonly known as ‘laughing gas’ and is currently used both in anaesthetics and as a ‘legal high’.

Dr Mick Whelan and Professor Heiko Balzter from our Department of Geography have just started a three-year NERC-funded project to explore the interaction between livestock (sheep) grazing behaviour, urine composition and subsequent nitrous oxide (N2O) emissions from urine patches.

Nitrous oxide is a greenhouse gas produced in the soil by micro-organisms. N2O is 180 times more powerful as a greenhouse gas, molecule for molecule than CO2.  Urine patches are now recognised as ‘hot-spots’ for N2O production and emission in grazed pastures.  It is, therefore, important to understand the factors which control emissions both locally and more broadly across wider areas.

Dr Whelan said: “Previous studies have been limited to measuring N2O emissions from controlled plot experiments where urine has been ‘applied’ to soil or have investigated emissions under lowland conditions (urine composition, soil types and climate). But in the new Upland-N2O project the research team will explore the effects of grazing and livestock movement in more extensive pastures, in upland areas where sheep have the opportunity to range and select herbage. This could influence urine composition and influence subsequent N2O emissions.”

Professor Balzter added: “The location of urine deposition could also influence emissions and is predicted to vary with soil pH, water balance and local climate.  In the uplands, soils are often more acidic and wetter than in lowland grazed pastures and the climate is often much harsher. The team will explore the effects of these vegetation, urine composition, soil and climate interactions on N2O emissions to get a better estimate of the greenhouse gas budget of the uplands, which cover about 40% of the UK.”

In addition to the University of Leicester, the project combines a team of researchers from Bangor University (who lead the project) with Rothamsted Research, Swansea University (in connection with Texas A&M University).  The field work will be based at Bangor University’s upland farm where the team will collate ‘layers’ of information believed to affect N2O production in soils, and subsequent emission, e.g. climate, topography, soil properties, vegetation composition, sheep movement, urine deposition patterns and urine composition (see Figure 1). Sheep urine will be collected and applied experimentally to upland soils and the N2O emissions measured using static and automated chambers (Figure 5). In addition, more-controlled experiments will also be conducted at Rothamsted Research’s North Wyke facility to determine which factors are important in controlling N2O production and emission from urine patches, e.g. the urine nitrogen content and the level of soil compaction (Figure 2).

Sheep will be fitted with collars (Figure 3) that include a variety of sensors to track their movement and behaviour in extensively grazed pastures on both enclosed hill land and open common land (Figure 4).  Knowledge of the geographical location of the sheep over time will indicate what they are eating (which can then be linked to their urine composition) and where they are urinating. This information will then be integrated by the Leicester team with other data ‘layers’ in a mathematical model to allow the team to predict spatio-temporal patterns of N2O emissions across different areas.


Notes to editors:

Professor Balzter is available at:

Dr Whelan is available at:

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