Soil Texture By Near Infrared Reflectance Spectroscopy.

NIR as a tool has been successfully applied to many types of soil analysis over the last 30 years.  In many cases, NIR offers rapid measurement with comparable accuracy to the reference method.  However, interferences in reflectance patterns from soils, arising from the presence of organic materials, have prevented adequate prediction of particle size distribution thus far.  This paper outlines a creative and iterative process necessary to arrive at useful and robust calibration equations for parameters that are elusive to capture by NIR.  Also summarized are recommended steps required to validate such calibration models, thereby attaching confidence to results.  All associated statistics are included in results.