ABSTRACT
In hydroponics, all essential elements are supplied to plants by dissolving fertilizer salts in water to make up the nutrient solution. The choice of salts to be used depends on a number of factors. The relative proportion of ions that a compound will supply must be compared with that required in the nutrient formulation. For example, one molecule of potassium nitrate (KNO3) will yield one ion of potassium (K+) and one of nitrate (NO3−), whereas one molecule of calcium nitrate (Ca(NO3)2) will yield one ion of calcium (Ca2+) and two ions of nitrate 2(NO3−). Therefore, if a minimum number of cations is required while supplying sufcient nitrate (anions) then calcium nitrate should be used; that is, half as much calcium nitrate as potassium nitrate would be required to satisfy the needs of the nitrate anion.
