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This article in SSSAJ

  1. Vol. 69 No. 3, p. 616-629
    Received: June 30, 2004

    * Corresponding author(s): yarai@usgs.gov
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Phosphate Reactivity in Long-Term Poultry Litter-Amended Southern Delaware Sandy Soils

  1. Yuji Arai *a,
  2. K. J. T. Livib and
  3. D. L. Sparksc
  1. a U.S. Geological Survey, 345 Middlefield Rd. MS 465, Menlo Park, CA 94025, and Dep. of Plant and Soil Sci., Univ. of Delaware, Newark, DE 19717
    b Dep. of Earth and Planetary Sciences, The Johns Hopkins Univ., Baltimore, MD 21218
    c Dep. of Plant and Soil Sciences, Univ. of Delaware, Newark, DE 19717


Eutrophication caused by dissolved P from poultry litter (PL)-amended agricultural soils has been a serious environmental concern in the Delaware–Maryland–Virginia Peninsula (Delmarva), USA. To evaluate state and federal nutrient management strategies for reducing the environmental impact of soluble P from long-term PL-amended Delaware (DE) soils, we investigated (i) inorganic P speciation; (ii) P adsorption capacity; and (iii) the extent of P desorption. Although the electron microprobe (EMP) analyses showed a strong correlation between P and Al/Fe, crystalline Al/Fe-P precipitates were not detected by x-ray diffraction (XRD). Instead, the inorganic P fractionation analyses showed high levels of oxalate extractable P, Al, and Fe fractions (615–858, 1215–1478, and 337–752 mg kg−1, respectively), which were susceptible to slow release during the long-term (30-d) P desorption experiments at a moderately acidic soil pHwater The labile P in the short-term (24-h) desorption studies was significantly associated with oxalate and F extractable Fe and Al, respectively. This was evident in an 80% reduction maximum in total desorbable P from NH4 oxalate/F pretreated soils. In the adsorption experiments, P was strongly retained in soils at near targeted pH of lime (≈6.0), but P adsorption gradually decreased with decreasing pH near the soil pHwater (≈5.0). The overall findings suggest that P losses from the can be suppressed by an increase in the P retention capacity of soils via (i) an increase in the number of lime applications to maintain soil pHwater at near targeted pH values, and/or (ii) alum/iron sulfate amendments to provide additional Al- and Fe-based adsorbents.

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