| 摘要 |
PURPOSE:To constantly keep ion concentration at the optimum level, by measuring a nutrient ion concentration in a hydroponic solution tank by an ion determination means and introducing a concentrated liquid from a concentrated liquid tank to the hydroponic solution tank when the measured nutrient ion concentration is out of the lower limit of the ion concentration to enable well growth of a plant. CONSTITUTION:A storage tank 1 contains a hydroponic solution produced by dissolving inorganic fertilizing nutrients in water and another storage tank 4 contains concentrated hydroponic solution having higher concentration of various nutrient ions than that of the normal hydroponic solution. An ion determination means 8 determines the concentration of at least one kind of ion among nutrient ions especially required for the hydroponic culture in the ions contained in the hydroponic solution in the tank 1. The ion concentration measured by the means 8 is compared by a controlling means 10 with the lower limit of the ion concentration necessary for the cultivation of a plant. When the determined ion concentration is lower than the lower limit, a signal is outputted to introduced the concentrated solution from the tank 4 to the tank 1 and a signal to stop the introduction is outputted when the determined ion concentration becomes higher than the lower limit of the concentration. The introduction and stop of the liquid is performed by a pouring means 6 according to the above signals. |
