Automation of an irrigation system refers to operation of the system with no or minimum manual intervention. The introduction of automation into irrigation system has increased application efficiency and drastically reduced labour requirement.
Various type of automation is possible. Some of them are,
(a) Time based system
(b) Quantity based system
(c) Moisture sensor based system
Total area to be irrigated is divided into small segments called irrigation blocks or zones and these zones are irrigated in sequence according to the flow of wate.r
Available from the water source.
In time based system, time is a basis of irrigation. Time of operation is calculated according to volume of water required and the average flow rate of water.
In volume based system, the preset amount of water can be applied in the field segments by using automatic volume controlled metering values. Sequencing of metering values can also be done automatically.
The moisture sensing system is the extension of time based system. Operation of irrigation values and controlled by the moisture sensors placed directly in to the root zone.
This device is the heart of the automation, which co-ordinates operation of the entire system. The controller is programmed to run various zones of an area for their required duration. In some cases moisture sensors are used with it which gives feed back to the controller about field moisture level.
The controller has inbuilt 24 - hr clock. There is an option to have different irrigation schedule for different days of the week. These are mostly multi station controller i.e. they can control 4/6/8/12 and even more number of solenoid valves through them. Other facilities available with the controllers are,
- Multi Programme facilities to suit different weather conditions.
- Weekly/fortnightly calendar or skip day’s interval option.
- Option to connect moisture sensors, temperature sensor, or other sensors having analog output.
B) Control Valves:
Replacement to conventional manual valve by either solenoid valve or hydraulic valve is necessary for automation.
These valves are operated on hydraulic pressure. The operation of the Hydraulic Valve depends on the type of Valve and whether it is NC (Normally closed) or NO (Normally Open) in principle.
A command can be transmitted to these hydraulics valves by means of control tubes and solenoid coils. These solenoid coils are mounted on the main line and connected to the valve by controlled tubing.
C) Solenoid Coils:
Solenoid coil is used to translate electric pulses into hydraulic pulses which enable opening and closing of specific hydraulic valves. These solenoid coils requires 24 V AC input for its operation. Solenoid coil when mounted on the valve are connected to controller by electrical cable. The size of the cable is the function of the distance between solenoid valve and the controller.