The control of closed soilless growing system in greenhouse agriculture

A control strategy for control in a closed soilless growing system is investigated, considering the combination of sensor technology and expert system technology. In the paper, the method based on curve fitting is introduced to calculate the density of NO/sub 3//sup -/, K/sup +/, Ca/sup 2+/ and the value of pH and EC. Considering the complexity of plant nutrition, we present a model for the control of nutrition ingredient. The experiment results show that the strategy is effective.