MINERAL ANALYSIS OF CORN LEAVES BY X-RAY-FLUORESCENCE ON GROUND VERSUS UNGROUND LEAF SAMPLES

Plant tissue analysis for non-mobile nutrients, can supplement soil test values or may replace soil analyses in the determination of the soil's ability to supply these nutrients to next year's crop. X-ray fluorescence (XRF) is a rapid technique for determining nutrient concentration in plant tissue. Typically, whole leaves are dried and ground for analysis by XRF or other chemical methods. Using a leaf punch to collect leaf sample disks the size of the XRF pellet (13-mm diameter) reduces drying time and eliminates grinding, thus reducing cost and analysis time. Leaf punch samples were collected from leaves of com plants grown on plots receiving different types of manure and rates of phosphorus. Leaf disks were pelleted for XRF analysis using both random and precision placement of disks in the pelleting die. After analysis, the sample pellets were ground and repelleted for XRF analysis. The three disk-handling methods had significantly lower values for some nutrients (S, Ca, Mn and Cu) than did identical whole leaf samples which contained the midrib. Nutrient content data from leaf punch disks randomly placed in the pellet die appear to provide adequate plant nutrient values for diagnostic purposes.