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Cattle excrete 75-95% of their nitrogen (N) intake. For dairy cows with a medium to high productivity, a large part of excreted N is in the form of urine. During grazing, urine patches on pastures experience a large local N input and thus form hotspots of potential nitrate leaching as well as emission of nitrous oxide (N2O). While it is known that grazing, compared to in-house husbandry, is advantageous concerning NH3 emissions (Voglmeier et al., 2018), the effect on N2O emissions is still uncertain. To investigate the processing of N in pasture urine patches and its effect on N2O emissions, we performed field experiments with controlled application of synthetic urine with typical patch sizes. Multiple urine applications were carried out between 2020 and 2023 on fenced-out areas of a pasture field in North-Eastern Switzerland (Barczyk et al., 2023). Two liters of standard synthetic urine was uniformly applied to circular areas of 0.12 m2. In selected experiments, patches of urine with different volumes and/or N contents were additionally produced. The different application times during the grazing season allowed to study the influence of varying environmental conditions. Repeated measurements after application included ammonium and nitrate concentration in the soil profile, exchange of N2O, and harvest N yield. The N2O emission was measured by manual and automated chambers. The automated chamber system was similar to the one described by Flechard et al. (2005) and Ammann et al. (2020). It allowed measurements with a high temporal resolution of about 4 hours. In one application experiment, the emitted N2O in the chamber headspace was analysed for its isotopic composition to identify the relevant source processes. The sampling of soil mineral nitrogen of urine treatments and untreated control plots in three depth layers took place at regular time intervals (weekly to biweekly) after urine application. The fresh soil was extracted with 0.01 M CaCl2 solution, and resulting extracts were analyzed photometrically for their nitrate and ammonium concentrations. The observed N2O emission time series were analysed for their temporal dynamics and corresponding driving parameters. An analysis using random forest modelling identified the time since urine application as most important predictor for the N2O emission flux. On average, the emission was greatest one day after application, declining continuously until about 30 days later. This course was very similar to the one of the soil ammonium concentration, while the nitrate concentration increased at the same time. This suggests that processes based on ammonium substrate (i.e. nitrification and nitrifier denitrification) were predominantly responsible for the N2O emissions. Furthermore, N2O emission time series were considerably modulated by water-filled pore space and soil temperature. Based on the very similar time course of N2O emission and soil ammonium concentration in urine patches – in combination with observed N2O isotopic signature – it is concluded that nitrification and nitrifier denitrification were the main sources of grazing related N2O emissions at the study site.