The influence of mineral fertilization (NH₄NO₃, KCl, NH₄NO₃ + KCI) on nitrogen leaching from three different soils has been studied in the model experiment. It has been proved that average mineral nitrogen leaching was 5 times after NH₄NO₃ + KCI and NH₄NO₃ application in comparison to control soil (the soil without addition). It was also stated that the average leaching of ammonium nitrogen and nitrate nitrogen depends in the soil type. The highest average quantity of nitrogen has leached from brown earth and podsol and the lowest from black earth.