Units of Results - Ask a laboratory representative what units are used for each test parameter. If results from different labs are compared, make sure the units associated with the results are the same. For a valid comparison, a simple conversion may be necessary. Ask the laboratory representative to explain the meaning of the units if they are unclear. Categories of Quantity - Some laboratories may place test results into categories.
Examples are the categories of low, medium, and high.
There may be additional categories or different categories than these. These categories usually denote a range of test values. It is likely that the categories given by one laboratory do not represent the same nutrient concentrations for another laboratory. Ask the laboratory to define each range that is used. That is, results that may be regarded medium for one crop may be considered low for another crop.