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This article in JEQ

  1. Vol. 35 No. 2, p. 611-616
     
    Received: Aug 4, 2005
    Published: Mar, 2006


    * Corresponding author(s): drsmith@purdue.edu
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doi:10.2134/jeq2005.0301

Dredging of Drainage Ditches Increases Short-Term Transport of Soluble Phosphorus

  1. Douglas R. Smith *a,
  2. E. A. Warnemuendea,
  3. B. E. Haggardb and
  4. C. Huanga
  1. a USDA-ARS, National Soil Erosion Research Laboratory, 275 Russell Street, West Lafayette, IN 47907
    b USDA-ARS, Poultry Production and Product Safety Research Unit, Fayetteville, AR 72701

Abstract

Managed drainage ditches are common in the midwestern United States. These ditches are designed to remove water from fields as quickly as possible, and sediment buildup necessitates dredging, to ensure adequate water removal. This laboratory study was conducted to determine the impact of ditch dredging on soluble phosphorus (P) transport. Ditch sediments were collected from a drainage ditch in northeastern Indiana immediately before and after dredging. The sediments were placed in a stream simulator, and stream water was loaded with 0.55 mM P for 5 d (adsorption experiment). Water was then removed, and “clean” water (no P added) was used for a desorption experiment, lasting 1 d. During the adsorption experiment, pre-dredged sediments were able to remove P from the water column quicker, and P concentrations 120 h after introduction of high P water were lower for the pre-dredged sediments (0.075 mM P) than the dredged sediments (0.111 mM P). During the desorption experiment, P was released to the water column slower in the pre-dredged treatment than the dredged treatment (instantaneous flux at t = 0 was 0.205 μM P h−1 for pre-dredged and 0.488 μM P h−1 for dredged). This occurred despite higher Mehlich 3–extractable P in the pre-dredged sediments than the dredged sediments. Equilibrium phosphorus concentrations (EPCo) were lower in the pre-dredged sediments during both adsorption and desorption experiments. Transport of soluble P immediately after dredging will likely increase in drainage ditches; however, dredging is a necessary management tool to ensure adequate discharge of water from surrounding fields.

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Copyright © 2006. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA

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