Use of PXRF for Rapid Tissue Analysis: Comparison with Traditional Techniques.

Leaf tissue testing is a critical component in determining crop nutrient deficiencies.  However, the time between sampling and analysis paired with the potentially dangerous and harmful chemicals needed is a major drawback for most wet chemistry methods.  With advancing technologies, more equipment and methodologies have the potential to decrease the amount of processing needed to accurately determine leaf nutrient concentrations.  One technology that has shown potential is portable x-ray fluorescence (PXRF).  This PXRF technology has been shown to be a valuable analysis technique in both soils and compost. However, little to no research is currently available to determine; 1) if the PXRF can be used to adequately estimate ICP values for plant tissue, and 2) proper methodology for PXRF scanning on plant tissue samples.  By using the PXRF, it would be possible to provide informative and rapid results to both researchers and producers. To evaluate the utility of the PXRF, nutrient analysis was compared for corn, cotton, and soybean samples on PXRF readings for both fresh and dried, ground tissue. The fresh tissue samples had lower coefficient of determination (r²) values for the majority of elements. However, fresh corn tissue was found to have a relatively strong relationship for Zn (r­²= 0.76). These relationships greatly improved when the samples were dried and ground, which potentially indicates the inability for the PXRF to manage for the varying matrix of the field-moist tissue samples.  The standard time duration for scanning provided adequate relationships for soybeans and cotton samples; however, this was not the case for corn samples.  Generally, increasing the scan duration improved the relationship compared to standard scanning duration.  These results indicate that the use of PXRF has the potential to be a vital tool for rapid plant tissue analysis, especially to determine problem areas in fields.