Effect of different zinc doses and organic fertilization on soil’s enzymatic activity

The enzymatic activity of soil was studied in a three-year pot experiment, where different amounts of zinc were introduced: 0, 200, 400, and 600 mg of Zn kg-1 of soil, as well as organic materials (control object, bovine manure, laying hens’ litter, spent mushroom substrate), used separately with the soil application dose of 2 g Corg kg-1 soil. Zinc and organic materials were used once, only in the first year of research, before sowing the test plant. In each year of the experiment, the test plant was orchard grass (Dactylis glomerata L.), harvested after 4 cuts. The activity of urease, dehydrogenases, as well as acid and alkaline phosphatase were determined in the soil collected after the last grass cutting, in each year of the study. Application of zinc to soil, regardless of its dose, resulted in a decrease in the activity of urease, dehydrogenase and alkaline phosphatase, although the significance of differences in relation to the control object was demonstrated only at higher doses, such as 400 and 600 mg Zn kg-1 soil. The study showed no negative effect of zinc on acid phosphatase activity. Organic fertilizers generally resulted in an increase in the enzymatic activity of the analyzed soil, and simultaneously limited the negative effects of higher zinc doses (400 and 600 mg Zn kg-1 of soil) on urease and dehydrogenase activity. During the consecutive years, urease and alkaline phosphatase activity decreased, while acid phosphatase activity increased. Dehydrogenase activity did not change significantly in the subsequent years of the study