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A Drain-Water Monitoring System for Soil-less Culture Growing
The Dagan, produced by Eldar Shany Technologies, is a unique system for monitoring and control of fertigation process in soil-less cultures growth, by automatic analysis of drainage water. In addition to irrigation Dagan is capable of controlling and monitoring both EC and pH levels in irrigation and drainage water.
The system automatically adjusts irrigation and fertilization dosage according to plant needs and climate conditions.
The Dagan system consists of following main components
1. An Elgal computerized controller, conducting both fertigation and drainage sampling procedures.
2. A central sampling unit (CSU), consists of an electronic pump, a set of switching control valves, a pH&EC measuring unit and a water counter.
3. A number of drain water collection units (DCU), each including a stainless steel tray ( 100cm length), a small bucket and a filter, located at selected plots in the greenhouse.
Optional
4. A solar radiation sensor used to measure light intensity changes in order to adjust irrigation cycles timing relatively to light conditions.
5. A communication system to a remote PC for data storage and analysis, and system's operation from the office.
Automation process
After each irrigation cycle the drain water samples are pumped off by the CSU and the values of their pH/EC levels and water volume are recorded by the controller. Based on the readings, the system is capable of automatically carrying the following operations:
1. Increase dosage of following irrigation cycle if:
 EC level is too high
Drainage quantity is insufficient
2. Decrease fertilizer concentration application at next cycle if EC level is too high.
3. Decrease acid concentration application at next cycle if pH level is too low.
4. Execute and immediate flushing program (water with reduced fertilizer concentration), if EC level is extremely high or pH level is extremely low.
5. Start irrigation cycles whenever accumulated solar radiation reaches a predetermined value.
Under cloudy conditions or at the morning or evening hours, the waiting periods between irrigation cycles are prolonged, while in sunny conditions they are shortened.
Advantages of Dagan system
Accurate irrigation, saving precious water and fertilizers.
Prevention of stress situation of the plants.
Close study of plant/water/substrate relations, using information stored at the PC.
Relatively low-cost system (only a single pair of EC/pH electrodes is needed).
Easy maintenance, due to it's simple design.
User friendly program- requires no preliminary know-how.
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