Recent Innovations in Portable X-Ray Fluorescence (PXRF) Spectrometry.

Portable x-ray fluorescence (PXRF) spectrometry is a rapid, proximal soil sensor capable of quantifying ~20 elements in-situ in 60 seconds with wide dynamic range (high % to low mg kg^-1). Already sanctioned by the USEPA for soil/sediment analysis, the USDA-NRCS has now referenced the technique in its new methods manual. Agronomic applications of the technology include determinations of cation exchange capacity, salinity, pH, and metal pollutant concentrations. When combined with visible near infrared diffuse reflectance spectroscopy, total N and total C determinations are also possible. Quality of results vary based on soil heterogeneity in relation to reference model parameters, but generally results are within 80-90% accuracy of standard lab methods. The clear advantage of PXRF over lab methods are its alacrity and portability. And, since results are obtained with no need for sample digestion or preparation, a greater number of scanning points across the landscape can be accomplished with no additional cost. Data can then be directly inputted into a geographic information system for soil spatial variability mapping with soil amendments, management techniques, or precision fertilizer applications adjusted accordingly. Summarily, this presentation will show applications of PXRF for multiple agronomic and environmental quality parameters of interest with the hope that consulting soil scientists will soon adopt this technology.