Abstract
A computer software program for aiding the mixture of macronutrients in nutrient solutions, named 'IonAdjuster', has been developed to select the best combination from various nutrient sources to determine required addition rates, according to user-specified demand and current analysis results. This software program is a personal computer spreadsheet program that runs on Excel 97. The user specifies the desired solution composition suitable for a cultivated plant by means of milli-equivalents or weight per volume of macronutrients. IonAdjuster determines the quantity of concentrated stock solution to be added from differences in required composition and the present macronutrient concentrations in solution. In practical hydroponic culture of tomatoes, fluctuation of ion contents of the solution was decreased and the percentage of top-grade fruit increased by the nutrient stock addition according to IonAdjuster. It is assumed that the combination of IonAdjuster and automatic ion sensing, such as that by a multi-ion meter, may allow for appropriate and continuous control of solutions in closed hydroponics. This developed system may result in higher crop production, more efficient use of fertilizer and elimination of groundwater pollution due to the drainage of large amounts of nutrient solutions from open hydroponic systems.
