OPTIMAL CONTROL OF WATER CONTENT, NUTRIENT CONCENTRATION AND BACTERIA IN TOMATO HYDROPONICS

Using porous ceramic sensors and equipment for ozone-ultraviolet ray sterilization, optimal nutrient solution control for hydroponics of a tomato crop has been examined. Monitoring of long term water chemical potential and electrical conductivity of the solution with tomato roots in rockwool results in lower fertilizer consumption compared with blind irrigation containing no information about the water content and nutrient concentration. For reuse of the unsucked solution, the effect of the sterilization was determined by analyzing the number of microbes in the circulatory solution during the sterilization. The number of microbes decreased by one fifteenth compared with the previous measurement, while the iron chelate in the sterilized solution precipitated as a decomposition product.