The data contains urination metrics including frequency, volume, chemical composition, estimated urine patch N loading rates and metabolomics profile of individual urine events from sheep (Welsh Mountain ewe) grazing a semi-improved upland pasture and a lowland improved pasture located in North Wales, UK. Urine collection studies were run in the spring, summer and autumn of 2016 for the semi-improved site and in autumn of 2016 on the lowland improved pasture. Sheep were housed in urine collection pens and while in the pens, each individual urine event was collected and stored separately. The study was conducted as a wider part of the NERC funded Uplands-N2O project (Grant No: NE/M015351/1). The frequency, volume and chemical composition of individual urine events has implications for nitrogen losses from the grazed pasture ecosystem, including emissions of the powerful greenhouse gas, nitrous oxide, and nitrate leaching. Full details about this dataset can be found at https://doi.org/10.5285/385ec5ab-0c47-46fc-b5df-008ca024296f