High spatial and temporal variability in nitrous oxide (N₂O) emissions on a field scale resulting from uneven distribution of animal excretal N and, denitrification and nitrification processes responsible for its production in soils, makes emissions extrapolation to farm-scales and beyond problematic. The processes regulating N₂O emission are also influenced by several climatic and environmental factors. Therefore accurate prediction of N₂O emission from simple empirical relationships is not possible. This paper investigates the suitability of a process-based NZ-DNDC model for assessing the amount of N₂O emission from Farm Dairy Effluent (FDE) irrigation in a dairy grazed pasture by comparing the modeled Water-Filled Pore Space (WFPS and N₂O emission from a dairy grazed pasture with and without FDE irrigation with the measured values during three irrigation events. The trend of the N₂O emission readings simulated by the NZ-DNDC model was similar to that observed under the field measurement for both the irrigated and the control treatment. The model was able to simulate the emission for the unirrigated grazed treatment but it slightly underestimated emissions for the FDE irrigated treatments. The modeled WFPS readings under both the unirrigated and the irrigated treatment were found to be within the range of the measured values with the WFPS. For the mineral N data the model was able to simulate the NH₄⁺ concentrations well but the NO₃^- concentrations were underestimated. It was observed that accurate simulation of WFPS is important for the accurate prediction of N₂O emission. Further, the NZ-DNDC model needs to be parameterized specifically for effluent irrigation in order to accurately predict N₂O emission from the grazed pastures irrigated with farm effluents.