PROBLEMS WITH DETECTING NUTRIENT AVAILABILITY IN EXPERIMENTAL HYDROPONIC SOLUTIONS

Chemical analysis of nutrient solutions used for hydroponic research experiments should show elemental concentrations equal to calculated values. In hydroponic experiments aimed at investigating ammonium toxicity and microelement chemical form and their effect on growing chrysanthemums, water analysis taken before the experiment did not yield elemental concentrations equal to calculated values. Therefore chemical additive and metal recovery experiments were conducted. Inductively coupled plasma (ICP) analysis of nutrient solutions soon after mixing produced concentrations equal to calculated values. After 24hours of refrigeration, results varied. If microelements were ionic salts, all except copper were overestimated. Solutions with chelates were closer to calculated values. Regardless of microelement form, macroelements were either under or overestimated. Ammonium in the complete solution made phosphorus, potassium, and calcium less detectable, but did not affect magnesium detection until phosphorus was added. Molybdenum and boron were overestimated. All elemental concentrations remained over time closest to calculated values when microelements were chelated.