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This article in JEQ

  1. Vol. 33 No. 2, p. 785-794
    Received: May 20, 2003

    * Corresponding author(s): glb5@duke.edu
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A Spatially Explicit Investigation of Phosphorus Sorption and Related Soil Properties in Two Riparian Wetlands

  1. Gregory L. Bruland * and
  2. Curtis J. Richardson
  1. Duke University Wetland Center, Nicholas School of the Environment and Earth Sciences, Box 90333, Durham, NC 27708-0333


Soils of riparian wetlands are highly effective at phosphorus (P) sorption. However, these soils exhibit extreme spatial variability across riparian zones. We used a spatially explicit sampling design in two riparian wetlands in North Carolina to better understand the relationships among P sorption, soil properties, and spatial variability. Our objectives were to quantify patterns of spatial variability of P sorption and related soil properties, and to determine which soil properties best explained the variability in P sorption after accounting for the effects of spatial autocorrelation. We measured bulk density, moisture, pH, soil organic matter (SOM), texture (percent clay, silt, and sand), oxalate-extractable aluminum (Alox), iron (Feox), and the phosphorus sorption index (PSI). Due to differences in texture, Alox, and Feox, the two sites had substantially different mean PSIs. At each site, we found considerable differences in the spatial variability of soil properties. For example, semivariance analysis and kriging illustrated that soil properties at Site 1 varied at smaller scales than those at Site 2. At both sites, after accounting for the effects of spatial autocorrelation and all other soil properties, we determined that Alox had the highest Mantel correlation with PSI. We believe this geostatistic and Mantel approach is robust and could serve as a model for research on other biogeochemical processes such as denitrification.

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Copyright © 2004. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA