AbstractUndisturbed soil cores collected from a 31‐year‐old Douglas‐fir (Pseudotsuga menziesii Mirb. Franco) plantation near Shawnigan Lake, B.C., were fertilized with (NH2)2CO (200 and 400 kg N ha−1) and NH4NO3 (200 kg N ha−1) and incubated for up to 5 months at 20°C/12°C (14‐hour day/10‐hour night) with air humidity of 80 to 85%. Cores with the 200 kg N ha−1 rate of fertilization were also given three monthly 24‐hour simulating precipitation treatments followed by incubation, starting 1 month after fertilization. Under conditions with or without precipitation, (NH2)2CO and/or NO‐2 were never detected in soil (forest floor plus mineral horizons) or leachates, and movement of ammonium (NH+4) beyond the forest floor was limited. In the absence of precipitation, a small amount of NO‐3 (9 to 18 µg N g−1 of dry soil) was detected in soil with (NH2)2CO fertilization, whereas up to 124 µg N g−1 of dry soil was detected with NH4NO3 fertilization. Redistribution of nitrate (NO‐3) was limited and approximately 90% of it remained in the forest floor. With precipitation, a NO‐3 concentration of 1 µg N g−1 was detected in soil over the study period after (NH2)2CO fertilization. With NH4NO3 fertilization, a maximum quantity of 32 µg N g−1 of NO‐3 was detected in the forest floor after the first precipitation treatment and only a trace (2 µg N g−1) was detected after the third precipitation treatment. Leaching of NO‐3, though small (10 mg N liter−1), was restricted to NH4NO3 fertilization. The recovery of nitrogenous fertilizers, (NH2)2CO or NH4NO3, as NH+4 plus NO‐3 never exceeded 53% of the amount applied. The incomplete recovery of the fertilizers as inorganic‐N could be due to biological immobilization of N, or interactions of organic matter with unhydrolyzed (NH2)2CO, NH+4 (from urea hydrolysis and NH4NO3 ionization), or NO‐2 (from NH+4 oxidation and NO‐3 reduction).