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This article in AJ

  1. Vol. 100 No. 3, p. 551-556
    Received: Feb 15, 2007

    * Corresponding author(s): david.clay@sdstate.edu
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Do Synergistic Relationships between Nitrogen and Water Influence the Ability of Corn to Use Nitrogen Derived from Fertilizer and Soil?

  1. Ki-In Kima,
  2. D. E. Clay *b,
  3. C. G. Carlsonb,
  4. S. A. Clayb and
  5. T. Trooienc
  1. a Post-doctorial fellow, USDA-ARS, North Central Soil Conservation Research Lab., 803 Iowa Ave., Morris, MN 56267
    b Plant Science Dep., South Dakota State Univ., Brookings, SD 57007
    c Agricultural and Biosystems Engineering Dep., South Dakota State Univ., Brookings, SD 57007


To improve site-specific N recommendations a more complete understanding of the mechanisms responsible for synergistic relationships between N and water is needed. The objective of this research was to determine the influence of soil water regime on the ability of corn (Zea mays L.) to use N derived from fertilizer and soil. A randomized split-block experiment was conducted in 2002, 2003, and 2004. Soil at the site was a Brandt silty clay loam (fine-silty, mixed, superactive frigid Calcic Hapludoll). Blocks were split into moderate (natural rainfall) and high (natural + supplemental irrigation) water regimes. Nitrogen rates were 0, 56, 112, and 168 kg urea-N ha−1 that was surface applied. Water, soil N, and N fertilizer use efficiencies were determined. Plant utilization of soil N was determined by mass balance in the unfertilized control plots and by using the δ15N approach in fertilized plots. Findings showed that: (i) plants responded to N and water simultaneously; (ii) N fertilizer increased water use efficiency (170 kg vs. 223 kg grain cm−1 in 0 and 112 kg N ha−1 treatments, respectively); and (iii) water increased the ability of corn to use N derived from soil (67.7 and 61.6% efficient in high and moderate water regimes, respectively, P = 0.002) and fertilizer (48 and 44% efficient in high and moderate water regimes, respectively, P = 0.10). Higher N use efficiency in the high water regime was attributed to two interrelated factors. First, total growth and evapotranspiration (ET) were higher in the high than the moderate water regime. Second, N transport to the root increased with water transpired. For precision farming, results indicate that: (i) the amount of N fertilizer needed to produce a kg of grain is related to the yield loss due to water stress; and (ii) the rate constant used in yield goal equations can be replaced with a variable.

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Copyright © 2008. American Society of AgronomyCopyright © 2008 by the American Society of Agronomy