Provenance & quality
Treatments were applied in a randomised block design within two contrasting seasons (summer and autumn), of 2017. In the summer experiment, treatments (n = 4) consisted of: i) control (no urine application), ii) artificial sheep urine (920 kg N ha-1), and iii) real sheep urine (930 kg N ha-1). In the autumn study, treatments (n = 4) consisted of: i) control (no amendment), ii) artificial sheep urine (1120 kg N ha-1), and iii) nitrate and glucose (106 kg N ha-1; 213 kg C ha-1). The latter treatment was applied to determine the capacity for denitrification related N2O emissions without substrate limitation. The real sheep urine was collected from sheep grazing vegetation at the site and was re-applied to the soil in discrete patches.
Greenhouse gas 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, with samples 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 solution mineral N dynamics (NH4+ and NO3-) and total dissolved N and dissolved organic C are provided, which were collected via Rhizon® soil solution samplers installed inside the chambers. Routine soil sampling from duplicate plots were also conducted, where the soil moisture (expressed as % soil water-filled pore space), soil pH and electrical conductivity following the treatment applications are reported. The soil temperature, air temperature and rainfall data covering the study periods are included, alongside characterisation of the soils within each experimental area. Full details of the methods and quality control procedures are provided in the supporting documentation associated with each deposited data file.