Design and implementation of low powered drip irrigation controller for citrus orchard

A low cost drip irrigation controller powered with battery was developed for applications in remote mountainous citrus orchards. This controller was designed to improve drip irrigation management efficiency and reduce the labor inputs, which in turn reduces the production cost. It is mainly composed of an ATMega88V microcontroller, power supplying circuit, human-computer interaction unit, pulse solenoid valve and its driving circuit. Power consumption of the controller was measured in 0-0.9 MPa pipe water pressure conditions with the supply voltage ranging from 0 to 10 V DC(Direct Current) by an adjustable digital power supply. The results indicated that the minimum voltage requirement for the controller to drive the valve was 3 V. Current for opening or closing the valve increased with the voltage supply and was hardly affected by water pressure. The quiescent current of the controller was 50 μA when the supply voltage was greater than 5 V. This current gradually increased to its maximum value of 149.2 μA with the process when the supply voltage dropped from 5 V to 3 V. Powered with a 9 V alkaline battery, the controller’s battery life was tested under the condition that the controller was programmed to drive the value open or close the valve alternately at 5-second interval. Results indicate that the battery can power the controller for 364 hours to open or close the valve 272 160 times during this period. It can be further estimated that a 9 V battery with a rated capacity of 2 500 mA·h can power the controller for more than 5 years, without considering self discharge and natural deterioration of the battery. Assessments carried out show that the controller is easy to use, and suitable for automatic controlled drip irrigation in medium and small sized citrus orchards.