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This article in AJ

  1. Vol. 94 No. 3, p. 435-441
    Received: June 25, 2001

    * Corresponding author(s): scharfp@missouri.edu
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Corn Yield Response to Nitrogen Fertilizer Timing and Deficiency Level

  1. Peter C. Scharf *,
  2. William J. Wiebold and
  3. John A. Lory
  1. Dep. of Agron., 210 Waters Hall, Univ. of Missouri, Columbia, MO 65211


Nitrogen fertilizer is typically applied to corn (Zea mays L.) shortly before planting, but there are several reasons why later N applications may be of interest: to spread work away from the busy planting season, to avoid the frequent wet field conditions in spring, to reduce or remedy in-season N loss in wet years, or to allow use of in-season diagnostic tools. One of the obstacles to the use of later N applications is the fear that irreversible yield loss will occur due to N stress. Our objective was to evaluate the yield impact of delaying N applications until the late vegetative growth stages and as far as silking. We conducted a total of 28 experiments with timing of a single N application as the experimental treatment. We found little or no evidence of irreversible yield loss when N applications were delayed as late as stage V11, even when N stress was highly visible. There was weak evidence of minor yield loss (about 3%) when N applications were delayed until stage V12 to V16. Only 3 of the 28 experiments had N applications later than V16—all were at silking and relative yields were 0.71, 0.89, and 0.95. Though full yield was not achieved when N applications were delayed until silking, yield was still highly responsive to N application at this stage—yield response exceeded 2.2 Mg ha−1 in all three experiments.

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Copyright © 2002. American Society of AgronomyPublished in Agron. J.94:435–441.