The effect of soil contamination with CuSO₄ · 5H₂O applied in the following doses of Cu kg^-1: 150, 300, 450 and 600 mg on the activity of dehydrogenases, urease and acid phosphatase and alkaline phosphatase was studied in a pot experiment. Two types of soil were examined: heavy loamy sand and silty sandy loam. The experiment was completed in two series: with yellow lupine cultivation and without plant cultivation. The enzyme activity in the soil samples was determined on days 14, 28, 42 and 56 of the experiment.
Based on the experimental results, soil contamination with CuSO₄ · 5H₂O doses of 150 mg, 300 mg, 450 mg and 600 mg Cu · kg^-1 significantly inhibited the activity of dehydrogenases, urease and acid and alkaline phosphatases. Dehydrogenases and urease were found to be better indicators of soil contamination with copper than the other enzymes studied. Compared to phosphatases, dehydrogenases and urease appeared to be better indicators of soil contamination with copper, as their activity was more strongly inhibited by copper than the activity of phosphatases. Enzymatic activities were dependent on the type of soil. Dehydrogenases and acid phosphatase exhibited greater activity in heavy loamy sand, while the activity of urease and alkaline phosphatase was greater in the silty sandy loam. Cultivation of yellow lupine stimulated the activity of dehydrogenases and acid phosphatase in both soils as well as that of urease in heavy loamy sand. Soil contamination with copper had a very negative effect on the yield of yellow lupine.