Fate of fertilizer N was investigated by the ¹⁵N mass balance method, and ammonia volatilization was measured by the micrometeorological technique after urea or ammonium bicarbonate was applied to spring wheat growing on a meadow chestnut soil at Zhangbei County, Hebei Province. The application rate of N fertilizer was totally 72.SkgN/ha, of which 1/3 was applied as basal dressing with seeding, and the rest 2/3 was applied as top dressing imn>adiately followed by irrigation.Results showed that plant recoveries, N remaining in 0-0.8m soil and total N losses of the applied N were 37.8%-48.3%, 33.8%-40.4% and 14.3%-25.4%, respectively. There was no apparent difference between the fates of urea N applied as basal dressing and top dressing. However, while N fertiliser was applied as top dressing, plant recovery was 10% higher from urea than from ammonium bicarbonate, and in contrast, N loss was 7.5% lower from the former than from the latter.volatilization was as low as 1% and 5% of the applied N when urea and ammonium bicarbonate were applied as top dressing, respectively. Results also showed that less than 1/3 of the N taken up by wheat was derived from the applied N fertilisers, and thus the rest was derived from the soil.