Development of an open source soil water potential management system for horticultural applications, “Open_Irr”.

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 4 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. SOURCE FILES: Open_Irr_Node_copy: Open_Irr Node program written in the Arduino IDE, uploaded to Moteino-Mega microcontroller in the Node unit. Should only be altered by advanced users. Open_Irr_Gateway_copy: Open_Irr Gateway program written in the Arduino IDE, uploaded to Moteino-Mega microcontroller in the Gateway unit. Should only be altered by advanced users. Gerber_HardwareX_Open_Irr_Node_PCB.zip: Open_Irr Node gerber zip file. Provide to PCB manufacturers to obtain PCB. Gerber_HardwareX_Open_Irr_Gateway_PCB.zip: Open_Irr Gateway gerber zip file. Provide to PCB manufacturers to obtain PCB. Schematic_HardwareX_Open_Irr_Node.pdf: Open_Irr Node electrical schematic of included components. Schematic_HardwareX_Open_Irr_Gateway.pdf: Open_Irr Gateway electrical schematic of included components.

摘要：近年来随着技术进步，基于传感器的数据驱动灌溉得以发展，但受限于准入成本壁垒，其公平普及仍难以实现。为此，本研究基于Arduino集成开发环境（Arduino IDE）开发了一款简易的微控制器（microcontroller）LoRa平台Open_Irr，用于采集土壤基质势（soil matric potential）的电阻式测量数据并自动触发灌溉事件。单个Open_Irr节点可连接至多16个Watermark®土壤传感器，并支持4路灌溉配置；节点采样频率、灌溉参数及无线电传输参数均可由无编程经验的终端用户自行调节。多个节点可接入单个网关，为灌溉自动化提供无规模限制的解决方案。本研究于2022年春季开展初步试验，以验证Open_Irr平台在缺水场景下的性能表现：Open_Irr采集的土壤基质势数据与商用Watermark®传感器读数仪的结果一致性良好（样本量n=655）；回归分析显示决定系数为0.91，Bland-Altman法估计的固定偏倚约为2千帕（kPa）。通过外接电磁阀（solenoid valves），Open_Irr平台可实现基于多种基质势阈值的滴灌自动化控制。本次试验结果表明，该平台适用于需要实现灌溉自动化或施加干旱胁迫（drought stress）的商业与学术园艺应用场景。

源文件：
1. Open_Irr_Node_copy：基于Arduino集成开发环境（Arduino IDE）编写的Open_Irr节点程序，需上传至节点单元的Moteino-Mega微控制器，仅高级用户可对其进行修改。
2. Open_Irr_Gateway_copy：基于Arduino集成开发环境（Arduino IDE）编写的Open_Irr网关程序，需上传至网关单元的Moteino-Mega微控制器，仅高级用户可对其进行修改。
3. Gerber_HardwareX_Open_Irr_Node_PCB.zip：Open_Irr节点的Gerber制版压缩文件，可提供给印制电路板（Printed Circuit Board，PCB）制造商以制作印制电路板。
4. Gerber_HardwareX_Open_Irr_Gateway_PCB.zip：Open_Irr网关的Gerber制版压缩文件，可提供给印制电路板（Printed Circuit Board，PCB）制造商以制作印制电路板。
5. Schematic_HardwareX_Open_Irr_Node.pdf：Open_Irr节点所包含组件的电气原理图。
6. Schematic_HardwareX_Open_Irr_Gateway.pdf：Open_Irr网关所包含组件的电气原理图。