Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School



Selenium is of interest to the animal nutritionists and to the biochemist from two standpoints. In some areas of the world it occurs in soils in excesses, and the plants growing in these soils contain levels of the element that are toxic to livestock that consume the plants. On the other hand, selenium appears to be essential to the well-being of certain animals, at least under some feeding regimens, and in a number of areas the soils produce feeds that are deficient in the element (48). In either case, an understanding of the cycling of selenium in nature is essential to the explanation of why certain soils produce plants deficient in the element while others produce plants which contain an excess. Such an explanation should be helpful, not only in the matter of mapping these areas, but also in terms of managing the lands for optimum production. Reviews by Allaway et al. (2) and by Olson (41) have dealt with the cycling of selenium in nature and have pointed to the need for further investigation of certain phases of it. The possible role of micro-organisms, for instance, has not been given adequate consideration. In part, having no adequate analytical method has contributed to the deficiency of information on this matter, the methods used until recently lacking the sensitivity and perhaps the accuracy required for this type of work. Recent advances in methods for the analysis of biological materials for selenium have opened the possibilities for further work, and it was the purpose of the investigations discussed here to study and adapt the newer methods of use in preliminary studies to evaluate the possible role of microorganisms in cycling selenium in soils and waters. The radioisotope, Se75, while extremely helpful in certain types of studies, cannot be substituted for the many forms of selenium that occur naturally in soils.

Library of Congress Subject Headings

Soils -- Selenium content




South Dakota State University