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

Authors: Bierer, Andrew

Submitted to: HardwareX
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2023
Publication Date: 7/20/2023
Citation: Bierer, A.M. 2023. Development of an open source soil water potential management system for horticultural applications, "Open_Irr". HardwareX. https://doi.org/10.1016/j.ohx.2023.e00458.
DOI: https://doi.org/10.1016/j.ohx.2023.e00458

Interpretive Summary: Recent advancements in technology have made automation of irrigation events in agriculture possible; however, these tools are often cost prohibitive for adoption by small farmers or research programs. Therefore, the authors have developed a microcontroller-based platform, Open_Irr, from low cost commercially available hardware to record soil moisture data and automate irrigation events based on sensor readings. The Open_Irr platform is a scale neutral alternative, as it can be deployed as a single unit or connected in a radio-mesh network. Customization of Open_Irr settings is made possible without programming experience through connection to an external PC or mobile phone. To validate the performance of the Open_Irr platform, we compared soil moisture readings with the manufacturer’s commercial alternative. The Open_Irr platform recorded values comparable to the commercial alternative. Further, the Open_Irr platform was demonstrated to reliably trigger irrigation events at user-defined levels of soil moisture content. As a result, the Open_Irr platform was found to be suitable for commercial and academic applications in irrigation automation.

Technical Abstract: 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 four irrigation settings; Node sampling frequency, irrigation settings, and radio transmission settings are 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 drought stress is desired.