CATIONIC SPECIATION IN NUTRIENT SOLUTIONS AS A FUNCTION OF PH

The pH of a nutrient solution is a property that is inherent to its co mposition. Changing the pH of a nutrient solution affects its composit ion, elemental speciation and bioavailability. The term 'speciation'' indicates the distribution of elements among their various chemical an d physical forms like: free ions, soluble complexes, chelates, ion pai rs, solid and gaseous phases, and different oxidation states. For a st andard nutrient solution elemental speciation is calculated for a pH r ange from 2 to 9. For each cation the formation of precipitates, ion p airs, complexes, and chelates is illustrated as a function of pH. The calculation of elemental speciation in nutrient solutions is an indisp ensable tool in the design, the analysis and the interpretation of exp eriments with the mineral composition of nutrient solutions in plant n utritional research.