The aim of this study was to determine the effect of mineral fertilization on the activity of alkaline and acid phosphatase and content of available phosphorus in soil under winter wheat cultivation. The fi rst factor of experiment was the fertilization with P, K, Mg, Ca and S in six levels: 1 (P, K, Mg, Ca and S), 2 (K, Mg, Ca and S), 3 (P, Mg, Ca and S), 4 (P, K, Ca and S), 5 (P, K, Mg, Ca), 6 (P, K, Mg, S). Second factor was the nitrogen fertilization in the form of ammonium nitrate (34% N) at doses:
0, 40, 80, 120, 160, 200 kg N ha-1. Soil samples were assayed for the activity of alkaline and acid phosphatase and for the content of available phosphorus by Egner-Riehm method (DL). The lowest content of available phosphorus was found in soil without P fertilization (K, Mg, Ca, and S). In the soil from those treatments, the activity of phosphomonoesterases was the biggest.  A low content of available phosphorus in the soil was also obtained in treatments without Mg and Ca application. A signifi cant effect of nitrogen fertilization on the activity of alkaline and acid phosphatase was found. Increasing doses of nitrogen resulted in the increased acid phosphatase activity while contributing to the reduction of alkaline phosphatase activity.