My Account: Log In | Join | Renew
Search
Author
Title
Vol.
Issue
Year
1st Page

Abstract

 

This article in SSSAJ

  1. Vol. 57 No. 3, p. 709-716
     
    Received: Feb 14, 1992
    Published: May, 1993


    * Corresponding author(s):
 View
 Download
 Alerts
 Permissions
 Share

doi:10.2136/sssaj1993.03615995005700030014x

Dispersion and Aggregation of Soils as Influenced by Organic and Inorganic Polymers and Inorganic Polymers

  1. Baohua Gu and
  2. Harvey E. Doner 
  1. Department of Soil Science, 108 Hilgard Hall, Univ. of California, Berkeley, CA 94720

Abstract

Abstract

In this study, the influences of three organic polyanions (a soil humic acid, a soil polysaccharide, and a commercial anionic polysaccharide) and hydroxy-Al polycations (Al-p) on soil clay dispersion, aggregation, and subsequently hydraulic conductivity were investigated. It was found that the organic polyanions, especially humic acid, were not flocculating agents, but were effective dispersing agents for the Na-clays and Na-soils. Removal of soil organic matter reduced soil clay dispersibility, whereas addition of small amounts of the polyanions increased soil clay dispersion. The Al-p effectively screened the surface negative charge on clay colloids and, in addition, acted as bridges between negatively charged colloids and the anionic polysaccharide, and thus prevented soil clay dispersion. Hydraulic conductivities of soil columns treated with Al-p or its combinations with the anionic polysaccharide or humic acid were about two orders of magnitude higher than those without addition of Al-p throughout the 5-d leaching period. Although treatment of the Na-soils with the anionic polysaccharide increased soil aggregate stability as measured by the wet-sieving method, it did not result in an increased soil hydraulic conductivity, due to redispersion of clay colloids after leaching with distilled water. This study indicates that soil colloidal stability is strongly influenced by soil organic components in addition to factors such as pH, ionic strength, and composition. In the absence of polyvalent cations, negatively charged humic substances, especially humic acid, may not contribute to stable soil aggregation, whereas the presence of both polyvalent cations and polyanions may be additive in preventing soil clay dispersion.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America