In order to improve plant factories, an appropriate control system on fertilization is urgently required. An automatic management system to control nutrient concentration was constructed using a programmable logic controller (PLC) and ion selective electrodes (ISEs) of nitrate, phosphate, and potassium ion. The concentration of nutrient components in a culture solution was monitored using these ISEs. When the concentration of the nutrient components diminished to the threshold set as an optimum condition (0.1 – 2.0 mM), an appropriate amount of a concentrated solution of each nutrient component was added to the culture solution using solenoid valves connected with the PLC. The present cultivation system was simply constructed without any computers and pumps. Three kinds of automatic control systems simultaneously worked and did not influence each other.

为了改善植物工厂，迫切需要适当的施肥控制系统。使用可编程逻辑控制器（PLC）和硝酸盐、磷酸盐和钾离子的离子选择电极（ISE）构建了控制养分浓度的自动管理系统。使用这些 ISE 监测培养液中营养成分的浓度。当营养成分的浓度降低到设定的最佳条件阈值（0.1-2.0 mM）时，使用与PLC连接的电磁阀将适量的每种营养成分的浓缩液添加到培养液中。目前的栽培系统结构简单，没有任何计算机和水泵。三种自动控制系统同时工作，互不影响。