Computer models are increasingly used to analyse environmental impacts of management measures in agricultural land uses. The Eferding basin is a major vegetable production region in Austria, where steadily rising nitrate concentrations in groundwater have been observed over the last decades. A sanitation program has been launched with management measures that reduce nitrogen fertilization rates by 30 %, or integrate cover crops. In this study, field measurements on seepage water, nitrate leaching, and crop yields are used for calibration of the bio-physical process model EPIC (Environmental Policy Integrated Climate). The performance testing of EPIC indicates that the model is able to predict yields, seepage water, and nitrate leaching. EPIC simulations over 20 years show decreased nitrate leaching from management measures that have reduced fertilization or introduce intercropping. Positive effects of cover crops on yields and soil condition could not be verified by modelling results. Nitrogen losses by leaching and ammonia volatilization significantly increase after 5 years (volatilization) and 10 years (leaching). Therefore, longer time analysis should be carried out to better evaluate the environmental impacts of alternative management measures. In addition, a simulation experiment is recommended to analyse the stochastic environmental effects due to the high variability of parameters directly affected by precipitation and temperature.