Phosphorus (P) is an essential element for all living organisms and food production. Recently, more and more investigations are based on assessing the risk of long-term use of phosphorus fertilizers on the environment and human health, due to the presence of cadmium, thallium, and radioactive uranium and thorium in them. The aim of this thesis was to determine the variability of the total concentrations of elements (uranium, thorium, chromium, nickel, lead, cadmium) in the soil due to insreased doses of phosphorus fertilization and different soil reactions (pH). The research included the analysis of 40 archived soil samples collected in 2016 from two stationary field experiments located in the central (Potok location – stagnosoil) and eastern part (Vukovar location - chernozem) of Croatia after a four-year application of increasing doses (0, 50, 100, 150, 200 kg P/ha) of phosphorus fertilizer (Triplex, 45%). From each experiment, 20 samples (5 treatments x 4 repetitions) were colected from the surface soil layer (0-30 cm). The contents of uranium, thorium, chromium, nickel, lead and cadmium were determined using the pXRF method. The results indicate that the stagnosol in the Potok had a very acidic reaction with an average value of 3.78, while the chernozem in the Vukovar had a neutral reaction with an average value of 6.82. Increasing doses of phosphorus fertilization in acidic soil had a significant effect on the variability of thorium, chromium, nickel and lead, while in neutral soil accumulated content of thorium and chromium were significantly influenced by phosphorus fertilization. The determined content of the observed elements varied in the range: 2-3 mg U/kg, 5-14 mg Th/kg, 97-133 mg Cr/kg, 25-49 mg Ni/kg and 14-20 mg Pb/kg. The pollution of stagnosol was detected in terms of thorium, chromium and nickel, while in chernozem in terms of thorium and chromium. The results of correlation coefficients indicate a very strong relationship between uranium and pH value in acid soil (r = -0.8371) and a strong relationship between thorium and plant-accessible phosphorus in neutral soil (r = 0.6711).