DOI: 10.5285/0434c74c-4a8e-45b8-a187-13e422c0ed0f
title: Sheep urine patch greenhouse gas emissions from a semi-improved upland grassland in North Wales, UK

description: The dataset contains annual soil greenhouse gas emissions following sheep urine (real and artificial) applications to a semi-improved upland grassland in North Wales, UK, across two seasons (spring and autumn) within the year 2016-2017. Soil greenhouse gas data were collected using a combination of automated chambers and manually sampled chambers, both analysed via gas chromatography. Supporting data include meteorological data, soil chemistry and above ground biomass data collected on a time-series throughout the study, following urine application. The data were used to calculate sheep urine patch nitrous oxide emission factors from an upland environment, to improve estimates of greenhouse gas emissions from extensively grazed agroecosystems.
description: The data pertains to two plot-based field trials, both arranged in randomised block designs. Treatments (n = 4) were applied in the spring and autumn of 2016 and measurements were taken across a full year following application. The treatments in spring consisted of a control (no urine application), real sheep urine application (applied at an equivalent rate of 756 kg N ha-1) and artificial urine application (applied at an equivalent rate of 1066 kg N ha-1). In the autumn, the treatments consisted of a control (no urine application), real sheep urine application (applied at an equivalent rate of 1112 kg N ha-1) and artificial urine application (applied at an equivalent rate of 1004 kg N ha-1).

Soil greenhouse gas (N2O, CO2 and CH4) fluxes were monitored from the experimental sheep urine patches for a full year (2016-2017). During the first nine weeks following treatment application, fluxes were monitored using a mobile automated greenhouse gas monitoring system (Queensland University of Technology, Institute for Future Environments, Brisbane, Australia) which samples from static chambers, analysing the samples for N2O and CH4 on a gas chromatograph (SRI 8610C, Torrance, USA) and CO2 fluxes on a LI-COR LI-820 (Licor, St Joseph, MI, USA). The system measures eight greenhouse gas flux measurements per chamber per day and is calibrated with certified reference gases to ensure accuracy. Subsequently, monthly manual greenhouse gas samples were taken from static chambers in the same plots to complete the year-round measurement of fluxes. Samples were analysed on a Perkin Elmer 580 gas chromatograph (Perkin Elmer Inc., Beverly, CT, USA), also calibrated with certified reference gases to ensure accuracy. The nature and units of the reported fluxes can be found in the supporting documentation associated with the fluxes. The N2O-N emission factors (% of N applied) were calculated from the N2O fluxes by calculating the cumulative emissions (area under the curve by trapezoidal integration) and expressing the proportion of applied urine-N emitted as N2O-N.

In addition to the greenhouse gas fluxes, the temporal dynamics of soil mineral N (NO3- and NH4+), total dissolved N, total dissolved organic C and gravimetric soil moisture are monitored throughout the study via soil sampling and analysis. Above ground biomass harvests were taken periodically and the foliar N content and C-to-N ratio determined. Supporting meteorological data are provided in addition to characterisation of the soil properties at each study site. Full details of methods and quality control procedures are provided in the supporting documentation associated with each deposited data file.