The Use of Color Infrared (CIR) Aerial Photography to
Determine the Spatial Variability of Crop Growth
Hydrology and Remote Sensing Lab

In order to ensure that long-term field trials on sustainable agriculture production systems will benefit from a high degree of experimental precision, it is necessary to locate experimental blocks in areas where potential grain yield is as uniform as possible. One technique that was used to assess the spatial variability of crop development at the sustainable agriculture field site was the analysis of CIR aerial photography.

CIR image showing contrast of healthy vegetation and bare soil CIR photography is able to spectrally separate vegetation from soil because it has an emulsion layer sensitive to near infrared radiation. This exploits the fact that vegetation, unlike soil, is highly reflective in the near infrared wavelength region. In CIR imagery, healthy vegetation has a red/magenta color; while bare soil is blue/gray in color.
Same CIR image in grayscale The amount of vegetation at the experimental field site can be quantified by ratioing the near infrared and red emulsion layers of the CIR imagery. The brighter the tone of grey, the more vegetation is present.
Contact: Wayne Dulaney wdulaney@rsrlgis.arsusda.gov

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