A Passive Drip Irrigation Controller for Efficient Water Use

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Globally, irrigation control for agriculture is typically done using rough estimations of a crop's water needs, a farmer's intuition, or on a schedule using a timer-based controller. This often leads to over- or underwatering, resulting in decreased plant growth and a loss of personal income, particularly for small farmers in regions experiencing water scarcity. Soil moisture sensors exist, but they are not widely adopted, and they still require the farmer to physically visit each crop to control the irrigation. Also, the general lack of electrical infrastructure in rural areas makes the use of electrically powered irrigation equipment (timers, actuation valves, pumping equipment) difficult to implement. The passive irrigation controller (PIC) being developed here automatically regulates the flow of water to an irrigation network without the need of electricity or an external control signal. It senses the crop's need for water by mechanically measuring the soil water potential, a measure of how dry a soil is, and directly uses this mechanical measurement to open or close the water control valve. The development of the PIC is in late-stage prototyping. Previously, we have validated in a laboratory setting that the PIC can open reliably, and consistently, at pre-determined soil water potential setpoints. We have made several iterations on the design and are currently comparing the irrigation performance of the PIC against a timer-based controller for growing tomatoes in a greenhouse. There is strong interest in implementation from technology developers at both ICARDA and the University of Guelph. This Lab2Market program will enable us to position the technology for maximum impact.