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This article in AJ

  1. Vol. 100 No. 4, p. 1211-1219
     
    Received: Sept 12, 2007


    * Corresponding author(s): eileen_perry@wsu.edu
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doi:10.2134/agronj2007.0306

Sensitivity of Narrow-Band and Broad-Band Indices for Assessing Nitrogen Availability and Water Stress in an Annual Crop

  1. Eileen M. Perry *a and
  2. Dar A. Robertsb
  1. a Center for Precision Agric. Systems, Washington State Univ., 24106 N. Bunn Rd., Prosser, WA 99350
    b Geography Dep., Univ. of California, Santa Barbara, CA 93106-4060

Abstract

We evaluated a suite of vegetation indices to detect treatment differences in nutrient and water availability in corn for areas larger and smaller than the ground sample diameter (GSD) from both a portable spectrometer and the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The ANOVA results for a N trial showed that indices based on the chlorophyll red-edge were more sensitive to differences in N treatment than those based on the visible and near infrared (NIR) regions only. Classifications of pixels for a spatial detection study using unfertilized strips with widths of 6 m, 12 m, 18 m, and 24 m were performed and scored as the percentage of correctly classified pixels. Generally, the indices using the red-edge produced more accurate detections, although none of the indices could detect nutrient stress in the 6-m strips based on 15-m imagery. A water stress study was set up in another location of the same field by withholding irrigation water. While the indices based on the chlorophyll red-edge outperformed others for N application detection, the visible and NIR indices differentiated water stress the best.

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