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This article in AJ

  1. Vol. 104 No. 4, p. 926-933
     
    Received: Jan 24, 2010
    Published: July, 2012


    * Corresponding author(s): dbarker@iastate.edu
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doi:10.2134/agronj2012.0030

Using Active Canopy Sensing to Adjust Nitrogen Application Rate in Corn

  1. D. W. Barker * and
  2. J. E. Sawyer
  1. Department of Agronomy, Iowa State Univ., Ames, IA 50011-1010

Abstract

Remote sensing that uses active sensors continue to be tested as an N stress detection method and provide in-season rate adjustments to corn (Zea mays L.). The objectives of the study were to use active canopy sensing to vary in-season N application at the V10 corn growth stage and compare applied N rate, grain yield, and nitrogen use efficiency (NUE) with N applied before planting. A fertilizer N rate study was conducted in 2009 and 2010 near Ames, IA. Pre-plant N rates were 0 to 270 kg N ha−1 and then sensor-based rates were applied in-season at the V10 corn growth stage. Rainfall events occurred 3 to 5 d after N application each year, providing corn response to the in-season applied N and increasing relative corn canopy biomass by the V13 growth stage. The pre-plant applied nitrogen (PP-N) 270 kg N ha−1 rate used as the N-reference did not result in the highest green normalized difference vegetative index (GNDVI) or produce the highest grain yields. The pre-plant plus sensor applied nitrogen (PP+S-N) recovered corn yield from plant N stress at V10. The best yield recovery with deficit pre-plant N and sensor-directed N application rate occurred each year when no pre-plant N had been applied. Overall, economic optimum nitrogen rate (EONR) and NUE in PP-N and PP+S-N were the same. The PP+S-N application does give corn growers options for addressing in-season N deficiency and protect yield potential when corn N need is uncertain or when soil N losses are unavoidable.

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Copyright © 2012. Copyright © 2012 by the American Society of Agronomy, Inc.