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Soil Science Society of America Journal Abstract -

Self-Diffusion of P in Kaolinite Treated With Ca or NH4 Salts and With an Organic Dye1


This article in SSSAJ

  1. Vol. 34 No. 2, p. 198-201
    Received: June 24, 1969
    Accepted: Aug 21, 1969

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  1. D. E. Peaslee and
  2. R. E. Phillips2



Self-diffusion coefficients of P ranged from 2.9 to 16.4 × 10-8 cm2 sec-1 in kaolinite clay that received treatments of salts and differing rates of gallein, an organic dye. The presence of 7.75 me/100 g clay of the NO3-, Cl- or SO42- salts of Ca or NH4 significantly decreased the diffusion coefficients of phosphorus from those of the untreated clay. Sulfate decreased the coefficients the least; coefficients in the presence of NO3- and Cl- were similar, but significantly less than in the presence of SO42-. The self-diffusion coefficients in the presence of the Ca-salts were significantly larger than those in the presence of the NH4-salts. When up to 5.2 m moles of gallein dye per 100 g of clay were added prior to the addition of P, diffusion coefficients increased in a linear manner. The effect of the dye was somewhat less when added after the addition of the P. The increases and decreases in diffusion coefficients induced by the treatments were reflected in changes in water-soluble P in the treated clay. Phosphorus was added to the kaolinite clay at the rate of 160 ppm for all treatments of salts and dye.

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