Effect of Varied Content of Molybdenum and Boron in Soil on Urease Activity

The aim of the study was to determine the effect of varied content of molybdenum and boron in soil on urease activity. Soil in a three-year pot experiment, to which different amounts of molybdenum (0, 0.05, 0.1 and 0.15 mgMo kg–1 of soil on a one-off basis as an aqueous solution of Na2MoO4 2 H2O) and boron (5, 10, 15 mgB kg–1 of soil as an aqueous solution of borax Na2B4O7 10 H2O) were used for analyses. Orchard grass and crimson clover were cultivated in the experiment. Four re-growths of the test plants were harvested during each vegetation period. Soil during each year of the experiment was analysed, after each re-growth of the test plants. Urease activity was determined by the Hoffman and Teicher method based on colorimetric determination of ammonia following enzymatic hydrolysis of urea. The application of increased amounts of molybdenum significantly increased the enzyme activity in soil samples taken after the grass and clover were harvested. Urease activity in soil samples taken after clover harvest was higher each year than in soil taken after grass harvest. No effect of increasing boron content on urease activity was observed in soil taken after the cultivation of test plants.