Vol 109 (1996): Proceedings of the Florida State Horticultural Society


Published December 1, 1996
  • leaf analysis,
  • nitrogen,
  • quality control


Agricultural producers and the fertilizer industry in the Southeast invest millions annually on soil and leaf testing. The results are used for diagnostics to determine nutrient inputs or to justify nutritional needs in response to government regulations. Full utilization of the results has been finite due to differences in analytical procedures used and limited understanding of the significance of the numbers. In addition the result reliability of leaf and soil testing laboratories have been often questioned. A survey of five laboratories in 1995 and six in 1996 showed them to differ from each other a minimum of 7.7% (Mg) and maximum of 50.4% (Fe) when the deviation was calculated as average of all samples. Reported concentrations for nitrogen in leaf tissue varied from 0.79% to 2.1% for the lowest and 3.27% to 3.54% for the highest sample. Average cumulative error for all samples and all elements combined varied from 4.6% to 20.0% in 1995 and from 5.6% to 18.1% in 1996. Given the variation found and the potential of the results being used to comply with governmental regulation use of unified procedures and regulation of QA/QC may be necessary to assure sufficient accuracy.