Date of Award:

5-1961

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Soil Science

Committee Chair(s)

H. B. Peterson

Committee

H. B. Peterson

Committee

S. A. Taylor

Committee

Norman Bauer

Committee

A. A. Bishop

Abstract

Sodium saturated Utah bentonite was equilibrated in several concentrations of various sodium salt solutions. The effect of anions on the amount of sodium adsorbed was determined. The effect of anions on the electrophoretic mobility of the clay was also studied. The results are reported herein.

Anions, are generally considered, in the field of surface chemistry, to have no influence on the amount of cations adsorbed or the electrophoretic mobility of negatively charged colloids (5, 10, 28, 41). There is evidence (2, 7, 24, 26, 27, 33) to indicate that anions sometimes have an appreciable effect. If anions influence the amount of cations adsorbed and the electrophoretic mobility of clay in soil material then they must have an influence on the surface potential. Many of the properties of soils are dependent upon their surface potential. Information concerning the amount of charge in surface potential could be of value in determining what effect irrigation water would have on the soil. This knowledge would also be of value in reclaiming sodic soils.

Current methods (39, 40) for determining the suitability of water for irrigation do not involve direct effects of anions on the surface properties of soil materials. If the surface properties of negatively charged soil materials are sufficiently influenced by their anion environment, such that these properties are changed by appreciable amounts, then methods for determining suitability of water for irrigation should give consideration to the effects of anions.

The hydraulic conductivity of soil materials often becomes very small during the reclamation of alkali soils because of the dispersion of the colloids. This is a serious problem as the rate of reclamation is dependent upon the rates of leaching and drainage which in turn depend upon the hydraulic conductivity. Hence, conditions which reduce the tendency of the soil materials to disperse should be employed. The tendency of a soil to disperse is a function of the surface potential; the greater the surface potential the greater the tendency. Therefore, if the surface potential of a soil material can be effectively reduced through its anion environment then the problem of preventing dispersion should be reduced accordingly.

Also, by reducing the potential of the surface, the degree of sodium saturation should be reduced. Sodium is the most readily replaced cation of those commonly found in alkali soils (43). Hence, if the surface potential of the material was decreased, sodium should be more readily desorbed than the other cations. This would result in a reduction in degree of sodium saturation of the soil material.

Checksum

909e6f364727023976afee513cc0f58a

Download

Included in

Soil Science Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .