An irrigation controller is a device to operate automatic

irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...

systems such as lawn sprinklers and

drip irrigation Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surfac ...

systems. Most controllers have a means of setting the frequency of irrigation, the start time, and the duration of watering. Some controllers have additional features such as multiple programs to allow different watering frequencies for different types of plants, rain delay settings, input terminals for sensors such as rain and freeze

sensor A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

soil moisture sensors Soil moisture sensors measure the volumetric water content in soil. Since the direct Gravimetric analysis, gravimetric measurement of free soil moisture requires removing, drying, and weighing of a sample, soil moisture sensors measure the volume ...

, weather data, remote operation, etc. There are two basic types of controllers,

electric Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

and

hydraulic Hydraulics () is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counterpart of pneumatics, which concer ...

. Most automatic irrigation valves are diaphragm valves in which the water above the diaphragm must be discharged for the valve to open. In a hydraulic system, the controller and valves are connected via small plastic tubes approximately 4 mm (¼ in) in diameter. The controller opens the tube connected to the valve, allowing that valve to open. Most newer systems employ electromechanical or electronic controllers. In this scenario, the controller is connected to an electrical circuit that operates a

solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whos ...

attached to each valve (

solenoid valve A solenoid valve is an electromechanically operated valve. Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the ...

). When the solenoid is actuated, the water above the diaphragm is relieved and the valve opens. Although sophisticated controllers that allow irrigation schedules to be automatically adjusted according to the weather have been available for many years, until recently these controllers were out of reach of the average consumer. One type is

evapotranspiration Evapotranspiration (ET) refers to the combined processes which move water from the Earth's surface (open water and ice surfaces, bare soil and vegetation) into the Atmosphere of Earth, atmosphere. It covers both water evaporation (movement of w ...

controllers or "ET controllers". Several

manufacturer Manufacturing is the creation or Production (economics), production of goods with the help of equipment, Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary se ...

s are now producing controllers that can be automatically updated by either a simple

weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...

sensor, via a

pager A pager, also known as a beeper or bleeper, is a Wireless communication, wireless telecommunications device that receives and displays Alphanumericals, alphanumeric or voice messages. One-way pagers can only receive messages, while response p ...

that receives a daily update from a network of local weather stations, or through soil moisture sensors. Several companies have also introduced products that gathers information from the internet to update the watering schedule.Los Angeles Times
/ref> There are broadly two categories of irrigation controllers: domestic ones for gardening applications, and professional controllers for more demanding agricultural applications. While most domestic (gardening) controllers can only open/close zones based on a time duration, without any feedback from the irrigation process, professional irrigation controllers can irrigate based on volume (quantities defined in cubic meters / Gallons), receive feedback from the process, and react to actual events happening during the process. For example, the typical professional controller will calculate the actual flow rate running in the system when a specific zone is operated, compare this to a pre-configured required amount, and adjust the irrigation process if deviation from the zone's flow rate is detected; This mechanism is called "Flow monitoring", and can prevent irrigation when a burst is occurring in the main line or in the zone's hydraulic components. The controller can also alert the operator locally via its interface, or remotely by sending an

SMS Short Message Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile phones exchange short text messages, t ...

or a message to a central control.

References

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Open Source Irrigation Controller that uses NOAA weather data for Hargreaves EvapoTranspiration methods
Gardening aids Irrigation

See also

References