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This article in JEQ

  1. Vol. 32 No. 1, p. 162-170
     
    Received: Sept 27, 2001
    Published: Jan, 2003


    * Corresponding author(s): Wigington.Jim@epa.gov
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doi:10.2134/jeq2003.1620

Nitrate Removal Effectiveness of a Riparian Buffer along a Small Agricultural Stream in Western Oregon

  1. P. J. Wigington *a,
  2. S. M. Griffithb,
  3. J. A. Fieldc,
  4. J. E. Bahamc,
  5. W. R. Horwathd,
  6. J. Owenb,
  7. J. H. Davisbd,
  8. S. C. Raina and
  9. J. J. Steinerb
  1. a NHEERL-Western Ecology Division, USEPA, 200 SW 35th St., Corvallis, OR 97333
    b USDA Agricultural Research Service, Corvallis, OR 97331
    c Oregon State University, Corvallis, OR 97331
    d CA 95616

Abstract

The Willamette Valley of Oregon has extensive areas of poorly drained, commercial grass seed lands. Little is know about the ability of riparian areas in these settings to reduce nitrate in water draining from grass seed fields. We established two study sites with similar soils and hydrology but contrasting riparian vegetation along an intermittent stream that drains perennial ryegrass (Lolium perenne L.) fields in the Willamette Valley of western Oregon. We installed a series of nested piezometers along three transects at each site to examine NO3–N in shallow ground water in grass seed fields and riparian areas. Results showed that a noncultivated riparian zone comprised of grasses and herbaceous vegetation significantly reduced NO3–N concentrations of shallow ground water moving from grass seed fields. Darcy's law–based estimates of shallow ground water flow through riparian zone A/E horizons revealed that this water flowpath could account for only a very small percentage of the streamflow. Even though there is great potential for NO3–N to be reduced as water moves through the noncultivated riparian zone with grass–herbaceous vegetation, the potential was not fully realized because only a small proportion of the stream flow interacts with riparian zone soils. Consequently, effective NO3–N water quality management in poorly drained landscapes similar to the study watershed is primarily dependent on implementation of sound agricultural practices within grass seed fields and is less influenced by riparian zone vegetation. Wise fertilizer application rates and timing are key management tools to reduce export of NO3–N in stream waters.

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Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.32:162–170.