The effect of annual (in 1974-1982) application of urea and ammonium nitrate on the fructification of macrofungi was investigated during the 1974-2011 period. Nitrogen application induced the fructification of Paxillus involutus, and its dominance reduced the total mushroom yield. Optimal conditions for P. involutus fructification were generated by the application of ammonium nitrate, whereas a higher average yield of macrofungi, similar to the yield in the control, was observed where urea was applied.