A system for fertigation management in closed-loop soilless culture of tomato

The actual development of greenhouse cultural systems is characterized by an increase in economic engagement, with a more high demand of advances techniques to optimize all productivity factors. Social and environmental constraints force growers to use lower impact systems and to adopt specific technologies for the reduction of resource exploitation: energy, water, etc. Electronics and computer science support this process, mainly by means of innovative sensors and efficient modeling that have become irreplaceable tools for the integration of knowledge and innovative technologies. The analysis of current experiences reveals a dual approach for controlling plant nutrition, called by Le Bot et al. (1998) “inductive or deductive regulations”. The first approach is applied to the actual practice of fertigation in open or closed types of soilless cultures and it is a posteriori regulation. In this case, nutrient solution with pre-set values of both pH and electrical conductivity (EC) is delivered to the crop with frequent or continuous EC measurements in the drain water. According to EC values of the drainage a modification of nutrient solution can be estimated, determining the intervention of the grower. In recirculating-water (closed-loop) growing systems, in order to reduce the use o