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This article in AJ

  1. Vol. 96 No. 4, p. 1196-1201
    Received: Dec 18, 2003

    * Corresponding author(s): ardell.halvorson@ars.usda.gov
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Nitrogen Fertilization and Rotation Effects on No-Till Dryland Wheat Production

  1. Ardell D. Halvorson *a,
  2. David C. Nielsenb and
  3. Curtis A. Reulec
  1. a USDA-ARS, 2150 Centre Ave, Bldg. D, Suite 100, Fort Collins, CO 80526
    b USDA-ARS, Central Great Plains Res. Stn., 40335 County Road GG, Akron, CO 80720
    c USDA-ARS, 2150 Centre Ave., Bldg. D, Suite 100, Fort Collins, CO 80526


No-till (NT) production systems, especially winter wheat (Triticum aestivum L.)–summer crop–fallow, have increased in the central Great Plains, but few N fertility studies have been conducted with these systems. Therefore, winter wheat (W) response to N fertilization in two NT dryland crop rotations, wheat–corn (Zea mays L.)–fallow (WCF) and wheat–sorghum (Sorghum bicolor L.)–fallow (WSF), on a Platner loam (fine, smectitic, mesic Aridic Paleustoll) was evaluated for 9 yr. Five N rates, 0, 28, 56, 84, and 112 kg N ha−1, were applied to each rotation crop. Wheat biomass and grain yield response to N fertilization varied with year but not with crop rotation, increasing with N application each year, with maximum yields being obtained with 84 kg N ha−1 over all years. Based on grain N removal, N fertilizer use efficiency (NFUE) varied with N rate and year, averaging 86, 69, 56, and 46% for the 28, 56, 84, and 112 kg ha−1 N rates, respectively. Grain protein increased with increasing N rate. Precipitation use efficiency (PUE) increased with N addition, leveling off above 56 kg N ha−1 A soil plus fertilizer N level of 124 to 156 kg N ha−1 was sufficient to optimize winter wheat yields in most years in both rotations. Application of more than 84 kg N ha−1 on this Platner loam soil, with a gravel layer below 120 cm soil depth, would more than likely increase the amount of NO3–N available for leaching and ground water contamination. Wheat growers in the central Great Plains need to apply N to optimize dryland wheat yields and improve grain quality, but need to avoid over-fertilization with N to minimize NO3–N leaching potential.

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