Chasing the Pee!
Dave Chadwick, Bangor University
Urine patches deposited to soils by grazing animals are recognised as hot-spots of emissions of the powerful greenhouse gas nitrous oxide (N2O). We don’t know enough about emissions of this gas from upland, extensively grazed areas, and this creates a large uncertainty in the national greenhouse gas inventory. There are over 5.5 million hectares of upland regions in the UK, and a significant proportion of livestock graze these extensive systems. These areas are not as well studied as lowland systems and contrast in the range and quality of forage on offer. Upland soils are generally more acidic and the climate tends to be cooler and wetter.
In our current research we aim to improve understanding of how sheep grazing behaviour, forage selection, urine composition and soil factors interact to increase the accuracy of direct N2O emission estimates from extensive upland systems. We’re using a range of approaches, making best use of the different areas of expertise provided by researchers at Bangor, Swansea and Leicester Universities, Rothamsted Research, and Texas A & M University. To detect animal ‘movement’, we’ve equipped sheep with GPS, which will tell us where and when they urinate. We’re also analysing the composition of the urine and the vegetation, mapping soil and landscape properties that may influence N2O emissions, and conducting trials to measure N2O emissions from sheep urine. We will link these different measurements to model upland N2O emissions in pastures.
Our field research is taking place at Henfaes Research Centre (Bangor University, Wales), where we studied an area of enclosed hill land (approximately 300 m above sea level) during the first grazing season. We’ve just started measurements for the second grazing season in Snowdonia National Park on an unfertilised pasture situated approximately 850 m above sea level. To find out more, take a look at the Uplands-N2O website and Twitter handle: @UplandsN2O