In-Situ Approximating Clay Contents with Aid of PXRF In Louisiana Soils.

Soil clay content is one of most important parameters for soil classification and field soil survey. The "feel method" of soil texture determination requires lots of expereiences and its results are often biased and even misleading. In Louisiana, most of the soils have similar parent materials, i.e., alluvium deposits, indicating similar clay composition accross the whole state. Previous studies have also reported that in alluvium soils, clay content is highly related with some metals including iron. As heavy metals can be readily determined in the field using PXRF, soil clay content could then be approximated if a significant correlation can be established between soil clay and metals. Based on the scans on soil samples collected at various locations in Louisiana, soil clay content was found closely correlated with iron percentage measured by PXRF. With the established equation, accurate clay content can then be easily obtained in the field with PXRF.