Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School


First Advisor

Ivan S. Palmer


Selenium has been found to be both essential for and toxic to animals and humans. Plants make up the main source of selenium for animals which are the food source for humans. Therefore, the selenium content in soils and plants is of interest. The uptake and accumulation of selenium by plants is governed by many environmental factors such as plant species, soil pH, soil type, the chemical form of the selenium and the presence of other ions. The most important factors regulating selenium uptake by plants are the concentration and the form of selenium present in the soil. Many authors have described the availability of selenium from different forms under various conditions. They found that the measurement of soluble selenium is the best relative index for the potential of selenium uptake by plants. Elemental selenium is very insoluble in water and is thought to be unavailable to crop plants. Fly ash which is produced in coal-burning electric power-generating plants contains appreciable amounts of selenium which is mainly elemental selenium. It has been reported that plants grown on soils amended with fly ash absorbed significant amounts of selenium. For instance, white sweet clover grown on fly ash accumulated as much as 205 ppm selenium. Generally, the uptake of selenium by plants has been correlated with the amount of fly ash added. In recent years, the emphasis of most studies on fly ash has been focused on the potential for using fly ash of known selenium content for increasing the selenium content of various crops to levels which would protect livestock from selenium-responsive diseases. Application of selenium salts to soil as a means of providing supplemental selenium to livestock is of limited use due to the high cost of the selenium salts. It has been reported that only very small amounts of elemental selenium can be solubilized and absorbed. Generally, selenium from this source would represent a very small amount of the total selenium in the plant. On the other hand, Cary and Allaway have demonstrated that elemental selenium can be transformed into more soluble forms by reactions that reduce elemental selenium, improving the availability of elemental selenium. The objectives of this work are to try to examine the availability of elemental selenium, to find the processes involved in the solubilization of the elemental selenium, and to determine the effect of drying on the selenium content of plants.

Library of Congress Subject Headings


Soils -- Selenium content

Selenium -- Solubility

Plants -- Nutrition



Number of Pages



South Dakota State University