Intensively used pastures may pose a serious risk to the environment due to the leaching of nitrogen compounds into groundwater. One of these risks is urine and dung left by cows on the pasture. Four experiments were located at Experimental Station of the Institute of Land Reclamation and Grassland Farming at Falenty on a pasture utilized for many years. Experimental plots of surface area 1 m² in eight repetitions were treated once with artificial urine at rate 60 g N·m⁻² that corresponded to 600 kg N·m⁻¹. In all experiments, a significant dependence of the content of both nitrogen forms on the presence of urine patch was observed. With the passage of time, the nitrate nitrogen content increasesd in successive layers in depth of soil profile to 60-80 cm deep. In the final stage of experiment almost whole mineral nitrogen load in the soil was exclusively nitrate nitrogen easily moving deep into soil profile. A urine patch acidified the topsoil layer.