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Soil Science Society of America Journal Abstract -

Anion Transport through Columns of Highly Weathered Acid Soil: Adsorption and Retardation


This article in SSSAJ

  1. Vol. 60 No. 1, p. 132-137
    Received: Oct 7, 1994

    * Corresponding author(s): msumner@uga.cc.uga.edu
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  1. Giampaola Bellini,
  2. Malcolm E. Sumner ,
  3. David E. Radcliffe and
  4. Nikolla P. Qafoku
  1. Via Donna Olimpia 218, Rome, Italy
    Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602



Subsoils of highly weathered, acid soils usually contain appreciable quantities of anion-exchange capacity (AEC), which retards the passage of anions through the profile. This AEC varies in magnitude with ambient soil solution parameters such as pH and ionic strength. In order to be able to predict NO-3 movement in such soils, estimates of the effect of subsoil charge characteristics on retardation are required. The effect of subsoil liming and ionic strength on the movement of NO-3 in repacked Kanhapludult soil columns was studied for this purpose. Columns comprising topsoil (untreated) over subsoil limed to different levels to give a range of AEC were used. The soil was first leached with a solution of 10 mmolc Ca(NO3)2 L-1 followed by a 10 mmolc CaCl2 L-1 solution. Convection-dispersion equation (CDE) parameters for Cl- were determined using CXTFIT. Liming reduced the retardation coefficient (R) from 2.39 in the unamended subsoil to 1.12 in the treatment that received 2.08 g Ca(OH)2 kg-1. Both subsoil pH (r2 = 0.96) and AEC (r2 = 0.98) were correlated with R for Cl-. To test the effect of electrolyte concentration on retardation, columns of untreated subsoil were leached with solutions of Ca(NO3)2 and CaCl2 at four input concentrations: 5, 10, 20, and 30 mmolc L-1. Retardation coefficients for Cl- at these concentrations were 2.81, 2.25, 1.76, and 1.51, respectively. Anion retardation needs to be taken into account in modeling NO-3 movement through acid subsoils.

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