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This article in SSSAJ

  1. Vol. 47 No. 3, p. 462-467
    Received: Aug 27, 1982



Effect of Soil Properties on the Kinetics of Phosphorus Desorption1

  1. A. N. Sharpley2



Relationships between the constants of a semilogarithmic modified Elovich and a logarithmic equation describing the kinetics of soil P desorption and physical and chemical properties of 60 soils, collected from throughout the USA, and volcanic ash were investigated. These relationships are needed for application of the equations to modeling soluble P transport in runoff from agricultural watersheds. The constants of the semilogarithmic equation (a and b) were significantly related to the extractable Al and CaCO3 content of acidic and basic calcareous soils, respectively. For the logarithmic equation, constants (K, α, and β) were related to the ratio of Fe- or clay-organic C content of the acidic soils and CaCO3- or clay-organic C content of the basic calcareous soils. It is suggested that these ratios represent an index of interactive specific surface area involved with P adsorption-desorption for a given soil. In contrast to the logarithmic equation, constants of the modified Elovich equation varied with soil P status and water-to-soil ratio. Thus, the former equation may have a wide application to describing soil P desorption in water quality models.

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