The utilization of initially-applied15N-labelled ammonium and nitrate nitrogen by wheat plants grown in soil was investigated in a pot experiment under controlled growth chamber conditions. The application rate was approximately 140 kg N ha−1) and the treatments consisted of {NH4}NO3, NH4{NO3}, {NH4NO3}, {NH4}2- SO4, K{NO3} and nil nitrogen. The ions in brackets ({ }) indicate those enriched with15N toc.5 atom %. On average, according to the isotope technique, 67.24±2.48% of the nitrogenous fertilizer was utilized by wheat. Significantly more nitrate N was recovered in the plants than ammonium N. Furthermore, when fertilized, less soil nitrogen is utilized by the plants compared with the controls, and the application of nitrate suppressed the uptake of soil N more than when ammonium N was applied. The results confirmed that, on average, the conventional method of determining fertilizer recovery by difference yielded lower values (47.49±8.93%) than those obtained with the tracer technique.