The aim of this study was to devise to synthesize the ¹⁵N labeled urea-formaldehyde fertilizer  in the laboratory condition and to compare the effects of various nitrogen sources applied in different amounts to three different soils having different chemical and physical characteristics. The experiment was set up in randomized block design with three replicates under growth chamber conditions (20±1°C,16/8 hr light/dark period, 20000 lux). The following nitrogen fertilizers were used to compare their effects at the rate of 0, 50, 100 and 150 ppm N:1. Ammonium sulfate (21% N, 5.85% ¹⁵N a.e); 2. Urea (46.0% N, 5.27% ¹⁵N a.e.); 3. Urea-formaldehyde (40.6%N, 3.52% ¹⁵N a.e AI=45.27, CWIN=19.97%, HWIN=10.93%). Grasses (30% poa pratensis + 30% red fescue + 30% lollium perenne) were used as the test crop and the above ground portions were harvested every month for six cutting. The dry matter (g/pot), total nitrogen content (%) total uptake (mgN/pot), nitrogen derived from fertilizer (Ndff,%) fertilizer use efficiency (FUE, %) were determined and compared for each cutting. The mean of six cutting results that the ammonium sulfate and urea fertilizers effects were found to be higher than urea- formaldehyde in every case. It can be explained this failure that urea-formaldehyde has in sufficient activity index.