The distribution and total recovery of15N‐labelled fertilizer nitrogen was studied in a 50‐year‐old mixed coniferous stand, consisting of Scots pine and Norway spruce, located in Uppland, Central Sweden. The experimental plots, with an area of 113 m2each, were separated from the surrounding trees by trenching and emplacement of an aluminium sheet to a depth of 50 cm. The standard nitrogen application rate was 150 kg N ha−1and the nitrogen sources tested were calcium nitrate, ammonium nitrate and urea. Two growing seasons after the application of fertilizer, all the experimental plots were subjected to destructive sampling, including soil, field vegetation and trees, with a view to producing a nitrogen balance sheet for the experimental treatments involved.