Avoid collecting surface or bottom residues since these contaminants alter results. Hydroponic Systems Flush lines sufficiently to ensure that the sample is representative of a thoroughly mixed supply solution. The information provided on the sheet ensures that the results are interpreted for your specific application. Forms are available from the Agronomic Division, area regional agronomists or County Extension offices. Refrigerate samples if they will be stored for more than one day.
Predictive samples receive a general interpretation without regard for site-specific details.
The diagnostic category should be selected when there is a special problem that must be solved. Diagnostic samples usually have matching plant tissue and soil samples to help pinpoint the problem. Paired samples from problem and nonproblem areas provide the most complete set of evidence for evaluation. Samples of source water should usually be taken when a nutrient solution is being evaluated. Diagnostic samples receive special site-specific interpretation by an agronomist based on details provided on the information sheet.