The Effect of Organic Matter Rich Amendments on Selenium Mobility in Soil

Abstract The soil organic matter (SOM) plays important role in the selenium dynamics in soil. Thus, the potential effect of vermicompost and digestate as important sources of organic matter in soil on the selenium (Se) mobility was assessed in this study. Three soils differing in their physicochemical parameters, fluvisol, chernozem, and luvisol were chosen for the experiment. Three types of vermicomposts based on various bio-waste materials as digestate, kitchen waste with woodchips and garden bio-waste were used for their high organic matter content. Additionally, the digestate sample was applied. For a detailed evaluation of the potential effect of vermicompost application on sorption characteristics of the soils, a batch sorption experiment was performed. The results showed a predominant effect of Se species in soil where selenite was more intensively sorbed compared to selenate, regardless of the soil type and treatment. In the control samples, the soil sorption ability of selenite tended to decrease in the order fluvisol > luvisol > chernozem. However, these differences were not significant. Moreover, the effect of the ameliorative materials depends on both soil and amendment used. In fluvisol, all the amendment applications resulted in decrease of K d values whereas in chernozem this effect was observed only for the digestate-based vermicompost 1. On the contrary, increasing distribution coefficient (K d ) levels were reported in luvisol treated with digestate and the application of garden bio-waste-based vermicompost 3 tended to decrease of the K d values. The long-term effect of the amendments on the Se mobility in soils as well as the more precise investigation of the role of the individual organic matter fractions in this context remain for the further research.