Oil palm cultivation has environmental impacts, including those associated with nitrogen (N) losses. Improving management practices to optimise yield and N losses is critical. In order to identify the key management and site parameters driving yield and N losses, over a 25-year cycle, we undertook a Morris's sensitivity analysis of the Agricultural Production Systems sIMulator oil palm model (APSIM-Oil palm), using 3 sites in Papua New Guinea. We selected 12 parameters and 3 outputs: yield, nitrous oxide (N2O) emissions and N leaching. The influence of the 12 parameters on the outputs depended on site characteristics, age of the palms, and climate. The most influential parameters for losses were N mineral fertiliser rate, drainage and fraction of legume in groundcover vegetation. The simulations suggested that APSIM-Oil palm is a useful tool for assessing management options for optimising yield and environmental outcomes in different environments. The results can also guide future measurements needed to improve N loss estimates, and further development of models and risk indicators.