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Journal of Environmental Quality Abstract - Waste Management

Selection of a Water-Extractable Phosphorus Test for Manures and Biosolids as an Indicator of Runoff Loss Potential


This article in JEQ

  1. Vol. 36 No. 5, p. 1357-1367
    Received: Oct 13, 2006

    * Corresponding author(s): Peter.Kleinman@ars.usda.gov
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  1. Peter Kleinman *a,
  2. Dan Sullivanb,
  3. Ann Wolfc,
  4. Robin Brandtd,
  5. Zhengxia Doue,
  6. Herschel Elliottd,
  7. John Kovarf,
  8. April Leytemg,
  9. Rory Maguireh,
  10. Philip Moorei,
  11. Lou Saporitoa,
  12. Andrew Sharpleyj,
  13. Amy Shoberk,
  14. Tom Simsl,
  15. John Tothe,
  16. Gurpal Toorm,
  17. Hailin Zhangn and
  18. Tiequan Zhango
  1. a USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802
    b Dep. Crop and Soil Sciences, Oregon State Univ., Corvallis, OR 97331
    c Agricultural Analytical Services Lab., Pennsylvania State Univ., University Park, PA 16802
    d Agricultural and Biological Engineering, Pennsylvania State Univ., University Park, PA 16802
    e School of Veterinary Medicine, Univ. of Pennsylvania, Kennett Square, PA 19348
    f USDA-ARS, National Soil Tilth Lab., Ames, IA 50011
    g USDA-ARS, Northwest Irrigation and Soils Research Lab., Kimberly, ID 83341
    h Dep. of Crop and Soil Environmental Sciences, Virginia Polytechnic Univ., Blacksburg, VA 24061
    i USDA-ARS, Poultry Production and Product Safety Research Unit, Fayetteville, AR 72701
    j Dep. Crop, Soil and Environmental Sciences, Univ. of Arkansas, Fayetteville, AR 72701
    k Dep. Soil and Water Science, Univ. of Florida, Gulf Coast Research and Education Center, Wimauma, FL 33598
    l Dep. Plant and Soil Sciences, Univ. of Delaware, Newark, DE 19716
    m Dep. Biological and Agricultural Engineering, Univ. of Arkansas, Fayetteville, AR 72701
    n Dep. Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078
    o Environmental Health, Greenhouse and Processing Crops Research Center, Agriculture and Agri-Food Canada, Harrow, ON, Canada N0R 1G0. Mention of trade names does not imply recommendation or endorsement by USDA-ARS


The correlation of runoff phosphorus (P) with water-extractable phosphorus (WEP) in land-applied manures and biosolids has spurred wide use of WEP as a water quality indicator. Land managers, planners, and researchers need a common WEP protocol to consistently use WEP in nutrient management. Our objectives were to (i) identify a common WEP protocol with sufficient accuracy and precision to be adopted by commercial testing laboratories and (ii) confirm that the common protocol is a reliable index of runoff P. Ten laboratories across North America evaluated alternative protocols with an array of manure and biosolids samples. A single laboratory analyzed all samples and conducted a separate runoff study with the manures and biosolids. Extraction ratio (solution:solids) was the most important factor affecting WEP, with WEP increasing from 10:1 to 100:1 and increasing from 100:1 to 200:1. When WEP was measured by a single laboratory, correlations with runoff P from packed soil boxes amended with manure and biosolids ranged from 0.79 to 0.92 across all protocol combinations (extraction ratio, filtration method, and P determination method). Correlations with P in runoff were slightly lower but significant when WEP was measured by the 10 labs (r = 0.56–0.86). Based on laboratory repeatability and water quality evaluation criteria, we recommend the following common protocol: 100:1 extraction ratio; 1-h shaking and centrifuge 10 min at 1500 × g (filter with Whatman #1 paper if necessary); and determining P by inductively coupled plasma–atomic emission spectrometry or colorimetric methods.

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Copyright © 2007. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyAmerican Society of Agronomy, Crop Science Society of America, and Soil Science Society of America