Within-field nitrogen response in corn related to aerial photograph color |
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Authors: | J D Williams N R Kitchen P C Scharf W E Stevens |
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Institution: | (1) Agribusiness, Plant and Animal Department, Brigham Young University, Idaho, Rexburg, ID, USA;(2) USDA-ARS, Cropping Systems and Water Quality Research Unit, Columbia, MO 65211, USA;(3) Plant Science Division, University of Missouri, Columbia, MO 54211, USA;(4) Plant Science Division, University of Missouri, Portageville, MO 63873, USA |
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Abstract: | Precise management of nitrogen (N) using canopy color in aerial imagery of corn (Zea mays L.) has been proposed as a strategy on which to base the rate of N fertilizer. The objective of this study was to evaluate
the relationship between canopy color and yield response to N at the field scale. Six N response trials were conducted in
2000 and 2001 in fields with alluvial, claypan and deep loess soil types. Aerial images were taken with a 35-mm slide film
from ≥1100 m at the mid- and late-vegetative corn growth stages and processed to extract green and red digital values. Color
values of the control N (0 kg N ha−1) and sufficient N (280 kg N ha−1 applied at planting) treatments were used to calculate the relative ratio of unfertilized to fertilized and relative difference
color values. Other N fertilizer treatments included side-dressed applications in increments of 56 kg N ha−1. The economic optimal N rate was weakly related (R
2 ≤ 0.34) or not related to the color indices at both growth stages. For many sites, delta yield (the increase in yield between
control N and sufficient N treatments) was related to the color indices (R
2 ≤ 0.67) at the late vegetative growth stage; the best relationship was with green relative difference. The results indicate
the potential for color indices from aerial photographs to be used for predicting delta yield from which a site-specific N
rate could be determined. |
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