Selenium content and enzymatic activity of soil after applying farmyard manure and mineral nitrogen / Zawartość selenu i aktywność enzymatyczna gleby po zastosowaniu nawożenia obornikiem i azotem mineralnym

The objective of this study was to evaluate the effects of different doses of farmyard manure (FYM) and nitrogen on the total selenium content in soil from different crop rotation systems. The aim of this study was to determine the changes of some oxidoreductases activity and Se concentration in soil in relation to applied doses of fertilisers over vegetation period. The experiment was carried out with the crop rotation systems - depleting and enriching in organic matter. The soil was fertilised with manure under potato in the doses of 0, 20, 40, 60 and 80 t • ha^-1 and with nitrogen in the doses of 0, 40, 80 and 120 kg N • ha^-1 under spring barley. The content of total selenium in the investigated soil was in the range of 0.060-0.230 mg • kg^-1. From the comparison of the results reported in literature, one can observe that the studied soil was poor in selenium. Over the investigated period, manuring resulted in an increase in the total selenium content in the soil and, for that reason, the FYM application can be recommended as a source of selenium in Se-deficient soils. Fertilisation with manure resulted in an increase in dehydrogenases and catalase activities in soil with increasing doses of FYM. The selenium content, as well as DHA and CAT activities, demonstrated clear seasonal variations. The present study indicated a significant relationship between the activity of soil enzymes, and the organic matter content, affecting the selenium status in soil and plants.