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This article in JEQ

  1. Vol. 37 No. 2, p. 362-368
     
    Received: July 12, 2007


    * Corresponding author(s): Sharpley@uark.edu
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doi:10.2134/jeq2007.0366

Phosphorus Loss from an Agricultural Watershed as a Function of Storm Size

  1. Andrew N. Sharpley *a,
  2. Peter J. A. Kleinmanb,
  3. A. Louise Heathwaitec,
  4. William J. Gburekd,
  5. Gordon J. Folmarb and
  6. John P. Schmidtb
  1. a Dep. of Crop, Soil and Environmental Sciences, 115 Plant Sciences Building, Univ. of Arkansas, Fayetteville, AR 72701
    b USDA-ARS, Pasture Systems and Watershed Management Research Unit, Building 3702, Curtin Road, University Park, PA 16802-3702
    c Centre for Sustainable Water Management, Lancaster Environment Centre, Lancaster Univ., Lancaster, LA1 4YQ, UK
    d USDA-ARS, Pasture Systems and Watershed Management Research Unit, Building 3702, Curtin Road, University Park, PA 16802-3702. Mention of trade names does not imply endorsement by the U.S. Government

Abstract

Phosphorus (P) loss from agricultural watersheds is generally greater in storm rather than base flow. Although fundamental to P-based risk assessment tools, few studies have quantified the effect of storm size on P loss. Thus, the loss of P as a function of flow type (base and storm flow) and size was quantified for a mixed-land use watershed (FD-36; 39.5 ha) from 1997 to 2006. Storm size was ranked by return period (<1, 1–3, 3–5, 5–10, and >10 yr), where increasing return period represents storms with greater peak and total flow. From 1997 to 2006, storm flow accounted for 32% of watershed discharge yet contributed 65% of dissolved reactive P (DP) (107 g ha−1 yr−1) and 80% of total P (TP) exported (515 g ha−1 yr−1). Of 248 storm flows during this period, 93% had a return period of <1 yr, contributing most of the 10-yr flow (6507 m3 ha−1; 63%) and export of DP (574 g ha−1; 54%) and TP (2423 g ha−1; 47%). Two 10-yr storms contributed 23% of P exported between 1997 and 2006. A significant increase in storm flow DP concentration with storm size (0.09–0.16 mg L−1) suggests that P release from soil and/or area of the watershed producing runoff increase with storm size. Thus, implementation of P-based Best Management Practice needs to consider what level of risk management is acceptable.

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Copyright © 2008. 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