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This article in JEQ

  1. Vol. 34 No. 6, p. 2243-2254
     
    Received: Feb 8, 2005
    Published: Nov, 2005


    * Corresponding author(s): john.schmidt@ars.usda.gov
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doi:10.2134/jeq2005.0047

In Situ Measurements of Nitrate Leaching Implicate Poor Nitrogen and Irrigation Management on Sandy Soils

  1. R. J. Gehla,
  2. J. P. Schmidt *b,
  3. L. R. Stonea,
  4. A. J. Schlegela and
  5. G. A. Clarkc
  1. a Department of Agronomy, Kansas State University, 2004 Throckmorton Plant Sciences Center, Manhattan, KS 66506
    b USDA-ARS, Building 3702, Curtin Road, University Park, PA 16802
    c Department of Biological and Agricultural Engineering, Kansas State University, 147 Seaton Hall, Manhattan, KS 66506

Abstract

Minimizing the risk of nitrate contamination along the waterways of the U.S. Great Plains is essential to continued irrigated corn production and quality water supplies. The objectives of this study were to quantify nitrate (NO3) leaching for irrigated sandy soils (Pratt loamy fine sand [sandy, mixed, mesic Lamellic Haplustalfs]) and to evaluate the effects of N fertilizer and irrigation management strategies on NO3 leaching in irrigated corn. Two irrigation schedules (1.0× and 1.25× optimum) were combined with six N fertilizer treatments broadcast as NH4NO3 (kg N ha−1): 300 and 250 applied pre-plant; 250 applied pre-plant and sidedress; 185 applied pre-plant and sidedress; 125 applied pre-plant and sidedress; and 0. Porous-cup tensiometers and solution samplers were installed in each of the four highest N treatments. Soil solution samples were collected during the 2001 and 2002 growing seasons. Maximum corn grain yield was achieved with 125 or 185 kg N ha−1, regardless of the irrigation schedule (IS). The 1.25× IS exacerbated the amount of NO3 leached below the 152-cm depth in the preplant N treatments, with a mean of 146 kg N ha−1 for the 250 and 300 kg N preplant applications compared with 12 kg N ha−1 for the same N treatments and 1.0× IS. With 185 kg N ha−1, the 1.25× IS treatment resulted in 74 kg N ha−1 leached compared with 10 kg N ha−1 for the 1.0× IS. Appropriate irrigation scheduling and N fertilizer rates are essential to improving N management practices on these sandy soils.

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Copyright © 2005. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA