Development of an open-source soil water potential management system for horticultural applications, " Open_Irr"

Development of data driven, sensor-based irrigation has become possible with recent advancements in technology, yet due to a cost-barrier to entry, equitable adoption remains out of reach. Therefore, a simple microcontroller based LoRa platform, Open_Irr, was developed in the Arduino IDE to record resistive measures of soil matric potential and automate irrigation events. A single Open_Irr Node may connect with ≤ 16 Watermark® soil sensors and manage 4 irrigation groups, with Node sampling frequency, irrigation settings, and radio transmission settings being end-user adjustable without programming knowledge. Multiple Nodes may connect with a single Gateway to provide a scale-neutral solution for irrigation automation. A preliminary trial was conducted in spring 2022 to validate the performance of the Open_Irr platform in water deficit scenarios. Open_Irr recorded soil matric potentials in line with a commercial Watermark® sensor reader (n = 655); regression analysis yielded a coefficient of determination of 0.91 with Bland-Altman estimated fixed bias of ∼ 2 kPa. The Open_Irr platform was demonstrated to automate dripline irrigation events at several matric potential thresholds through connection to external solenoid valves. This demonstration directly conveys suitability for commercial and academic horticultural applications where automation of irrigation events or imposition of edaphic water stress is desired.