2019 ASHS Annual Conference

Preparation of nutrient solutions for hydroponic culture is often challenging especially when the raw water quality is suboptimal. The universal use of preformulated commercial fertilizers for hydroponic solutions may be undesirable when raw water contains high levels of minerals. If the raw water contains high concentrations of salts which are non-essential plant nutrients such as Na⁺ and Cl^-, macronutrients added to the nutrient solution must be adjusted to counteract the detrimental influence of excess salts. To prepare a commonly used standard hydroponic solution containing (in meq/L) of 3 Ca²⁺, 2 Mg²⁺, 6 K⁺, 2 NH₄⁺, 10 NO₃^-, 2 SO₄^2-, and 1 H₂PO₄^- is simple if raw water contains no or low levels of minerals. The amount of macronutrients added to the nutrient solution being prepared has to be adjusted to accommodate the levels of each of the cations and anions already present in the raw water. The pH, mineral contents, and alkalinity of raw water, especially ground water, vary greatly by geographic regions. A simple system of balancing the cationic and anionic macronutrients and pH adjustment for optimum hydroponic solution according to water analysis will be presented.