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This article in SSSAJ

  1. Vol. 74 No. 1, p. 240-249
     
    Received: Mar 24, 2009


    * Corresponding author(s): tss1@cornell.edu
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doi:10.2136/sssaj2009.0123

Effect of Soil Reduction on Phosphorus Sorption of an Organic-Rich Silt Loam

  1. Wei Zhang,
  2. Joshua W. Faulkner,
  3. Shree K. Giri,
  4. Larry D. Geohring and
  5. Tammo S. Steenhuis *
  1. Dep. of Biological and Environmental Engineering, Riley-Robb Hall, Cornell Univ., Ithaca, NY 14853

Abstract

Phosphorus flux from agricultural landscapes to surface waters may cause eutrophication. In the northeastern United States, P transport largely depends on P sorption of soils in variable source areas or in land treatment systems. Soil redox fluctuation commonly occurs in these areas. Nevertheless, the effect of soil redox on P sorption has been variable in the literature. This study investigated P sorption of an organic-rich northeastern glaciated silt loam (Langford) under air-dried, field-wet, and reduced conditions using batch P sorption experiments. Additionally, the influence of farm wastewater on soil P sorption was studied. Major results indicated that soil reduction increased the maximum amount of P that can be sorbed (S max) and decreased the aqueous P concentration at which P sorption and desorption are equal (EPC0), both determined from a modified Langmuir isotherm model. The slightly reduced field-wet soils had no significant difference in S max due to limited soil reduction. Using the diluted wastewater as the sorption solution matrices instead of 0.01 mol L−1 KCl solution, the soils generally exhibited greater S max and lower EPC0 except for the EPC0 of a reduced surface soil, implying more complex P sorption in the field. Identified P sorption mechanisms include phosphate precipitation, ligand exchange with organic matter, and adsorption onto Fe hydroxides. Transformation of Fe compounds during soil reduction is primarily responsible for the changes in soil P sorption.

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