Correction of Imagery for soil mapping

I just read an article entitled "Considerations for atmospheric correction of Surface Reflectance for Soil Survey Application" by Matthew Levi and Craig Rasmussen.  It was published in Soil Survey Horizons.  Methodology is available to adjust photo tones that may be "off" because of camera angle, sun angle, and clouds.  The authors had trouble getting the whole system to work because their images did not meet all the parameters required for correction. 

My take on this issue is that it is possible on many circumstances to use a number of images to make decisions about soil line placement and soil boundaries.  How is this done?  The miracle of Google Earth.  Google Earth has a large number of images available.  Not all significant features show up in images every year.  I have been successful in identification of significant soil features by examining a number of different images.  The miracle of this is that Google Earth is available at no charge.  Features can be digitized and saved as KML or KMZ files.  A good GIS such as Global Mapper can import the KML or KMZ files so you can make them a part of soil  management zones. 

Relying on only one image for designation of management zones can be misleading.  Multiple images can be useful in identifying problem areas.  Camera angle, crop cover, time of day and time of year can all affect the usefulness of remote sensing data.  In addition, some data is only useful on the day it was recorded.  Infrared comes to mind.  Timing is everything in Infrared for ag interpretations.