Seasonal Changes of Selenium and Selected Oxidoreductases in Soil under Manure and Nitrogen Fertilzation

Abstract

The aim of the study was to determine the changes of total and available Se concentrations in soil and some oxidoreductases activity in relation to applied doses of fertilizers over vegetation period. The experiment was conducted applying the following crop rotation system – potato – winter wheat with intercrop – spring barley+ undersown – red clover and grasses designed in a split-plot with four replications. The soil was fertilized with farmyard manure (FYM) at doses 0, 20, 40, 60 and 80 Mg ha (under potato) and with nitrogen at rates 0, 30 and 60 kgN ha under red clover and grasses. Total selenium content in soil under red clover and grasses cultivation ranged from 132 to 169 g kg, what indicates that analysed soil is poor in this microelement. FYM fertilization significantly increased total selenium content in the soil with increasing doses of this fertilizer. The highest amounts of total selenium were found in soil at the beginning of the investigation period. The highest content of phytoavailable fractions and their share in the total selenium were observed in the case of fertilization with FYM at a dose of 40 Mg ha and then decreased with increasing doses of FYM. FYM fertilization as well as mineral nitrogen stimulated the activity of the investigated oxidoreductases, in comparison with non fertilized soil. The highest amounts of enzymes activity were obtained in July. The calculated correlation coefficients between total selenium and organic carbon and total nitrogen content in soil; enzymes activity and organic carbon and total nitrogen and between total selenium content and DHA activity, confirmed a close inter-relationship among these parameters.