PlantControl CX
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PlantControl CX A high performance, multi-functional irrigation control system Dr. Walter Schmidt / PlantCare AG PlantCare Ltd. I Sennhof 13 I CH-8332 Russikon I Switzerland +41 (0)44 463 77 88 I info@plantcare.ch I www.plantcare.ch Copyright © 2012 PlantCare Ltd. All rights reserved. excellence in smart irrigation

PlantControl CX A high performance, multi-functional irrigation control system Introduction In a report of the World Economic Forum (WEF) 2014 about the largest risks for humanity, the problem “water” has the third rank. It is expected that in the course of global warming, as well as the further sharp increase in population in Asia and Africa, the water will still gain additional importance (Fig. 1). Water is a strategic resource and all efforts must be made to use this vital substance sparingly. Fig.1: Source: World Economic Forum, Global Risk Perception Survey 2013-2014 Approximately 70%...

PlantControl CX A high performance, multi-functional irrigation control system Therefore, a very strong market growth is predicted for the so-called "smart irrigation“. (Fig. 2). PlantCare Smart Irrigation Control On the basis of a novel method for measuring the amount of plant-available water, PlantCare has developed an irrigation controller (PlantControl CX), which is designed specifically for use on farms and has a number of significant advantages over all previously offered systems. The PlantControl CX has been field-tested in recent years in a number of applications in and has achieved...

PlantControl CX A high performance, multi-functional irrigation control system The soil physicists talk about matrix potential, which corresponds to the energy that is necessary to pull out the water that is retained in the pores of the soil by capillary forces. In many cases this potential is equated with the energy required to raise the plant to extract water from the soil. But this is a misconception, since the plant roots have no pores or capillaries. The plants absorb the water only by osmotic forces, i.e. the ion concentration in the roots is higher than in the soil, which means that...

PlantControl CX A high performance, multi-functional irrigation control system Micro-Heat-Pulse (MHP) Method (PlantCare) PlantCare has been able to develop a new type soil moisture sensor which eliminates the disadvantages of other sensor technologies. The PlantCare soil moisture sensor is based on a micro-thermal measurement and the result is - as with all other sensors - not an absolute value for the soil moisture, but a time, which is a measure of the soil moisture. A small tip is heated up by a heating element for a few seconds by about 1° C. After this heating period, the cooling curve...

PlantControl CX A high performance, multi-functional irrigation control system - The sensors are easy to install and the embedding in the surrounding soil is not critical as it is in the case of tensiometers. The sensors are small and can be simple inserted into pre-drilled holes. The measurement can also be done close to the surface, which is not possible with capacitive measuring processes. All components are hermetically sealed against moisture and the materials used will not rot even after long usage in the soil. Therefore, the sensors are completely maintenance free. - The energy...

PlantControl CX A high performance, multi-functional irrigation control system PlantControl CX Irrigation Control System 200 m Electro-Pumps Diesel-Pumps Data analysis Monitoring Remote data retrieval Remote setting Active SMS alarming 3 km Soil moisture sensor 20 km Fertilizer mixer Fertilizer injectors Wireless valve control Fig.9: PlantControl CX System The reliable measurement of soil moisture is an absolutely necessary prerequisite for the design of an intelligent irrigation control (Fig. 9). In addition, other important conditions have to be fulfilled: - Each irrigation zone must be...

PlantControl CX A high performance, multi-functional irrigation control system Basic Functions The PlantControl CX performs the following basic functions: -It is able to control 32 valves, of which # 1 must always be used as the master valve. The interface to the valves is performed by modules, each having 8 valve outputs. The number of such modules can be selected as needed from one to a maximum of 4. -These modules can optionally control 24VAC valves or 9V DC pulse-controlled valves. The modules can also be mixed (24VAC - 9 VDC). -In addition, a multifunction switch module with 5 floating...

PlantControl CX A high performance, multi-functional irrigation control system To illustrate the types of controls, an example with 5 valves is shown in the adjacent figure (Fig. 10). As it is shown valve 4 is a clone of valve 2 and valve 5 is a clone from the valve 3. Monitoring can not be shown here, since this mode requires no valve. Furthermore, it is possible to connect a timer-output in parallel to a senor controlled valve. This means that a sector is always watered independently of the automatic watering when the timer provides for irrigation. This is, for example, advantageous if...

PlantControl CX A high performance, multi-functional irrigation control system The following figure shows the main differences between the various types of control. In each case, the soil moisture is plotted in the vertical and time is plotted in the horizontal axis. Fig.12: Control modes applicable for any valve 1: Timer - Mode: The timer always switches irrigation on and off at the pre-set times regardless of whether the soil is still wet or already too dry. 2: Semi Automatic - Mode: This mode requires the use of soil moisture sensors as a dry-threshold must be pre-defined. This ensures...

PlantControl CX A high performance, multi-functional irrigation control system This process is shown schematically in the following figure. Irrigation is not stopped until no change is measured between two successive measurements (3). Then, the water supply is shut off and waited a certain time until the excess water is seeped (field capacity) (4). Fig.13: Self-calibration procedure The system stores the value of the first measurement (1), a value at a higher moisture (2), the value at complete saturation (3) as well as the value of the field capacity (4). From this, the slope of the line...