ABSTRACT

A comprehensive review of automation of irrigation based on volumetric soil water content (VSWC) in the framework of IoT (Internet of Things) is presented. The fundamentals of electromagnetic sensors based on soil dielectric permittivity and the techniques used for measuring the VSWC are briefly described. Factors affecting sensor performance that have to be considered for selecting the appropriate sensor along with a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis are outlined. Special attention must be paid to the small soil volume explored by these sensors, installation accuracy, calibration, power supply and consumption and the effects of salinity on the soil water content. Since it is connected to a telemetry system, a wireless sensor network should include robust transmission units, energy-efficient processor, flexible configuration of the I/O ports, long-life battery, and a friendly software platform. A bidirectional wireless network layout allows sensor activity to be monitored, acts on solenoid valves to trigger irrigation (based either on direct VSWC values or algorithms) and provides real-time feed-back information of the soil-plant-atmosphere continuum. As revealed by the field research studies, significantly higher water, energy and labour savings were possible using automated irrigation based on VSWC sensors than with conventional irrigation scheduling based on computed evapotranspiration.

摘要

提出了在 IoT（物联网）框架下基于体积土壤含水量 (VSWC) 的灌溉自动化的全面回顾。简要描述了基于土壤介电常数的电磁传感器的基本原理和用于测量 VSWC 的技术。概述了在选择合适的传感器以及 SWOT（优势、劣势、机会和威胁）分析时必须考虑的影响传感器性能的因素。必须特别注意这些传感器探测到的小土壤体积、安装精度、校准、电源和消耗以及盐度对土壤含水量的影响。由于连接到遥测系统，无线传感器网络应包括强大的传输单元、节能处理器、灵活的 I/O 端口配置、长寿命电池和友好的软件平台。双向无线网络布局允许监测传感器活动，作用于电磁阀以触发灌溉（基于直接 VSWC 值或算法）并提供土壤-植物-大气连续体的实时反馈信息。正如实地研究所揭示的那样，使用基于 VSWC 传感器的自动灌溉比使用基于计算蒸发量的传统灌溉计划可以显着节省水、能源和劳动力。作用于电磁阀以触发灌溉（基于直接 VSWC 值或算法）并提供土壤-植物-大气连续体的实时反馈信息。正如实地研究所揭示的那样，使用基于 VSWC 传感器的自动灌溉比使用基于计算蒸发量的传统灌溉计划可以显着节省水、能源和劳动力。作用于电磁阀以触发灌溉（基于直接 VSWC 值或算法）并提供土壤-植物-大气连续体的实时反馈信息。正如实地研究所揭示的那样，使用基于 VSWC 传感器的自动灌溉比使用基于计算蒸发量的传统灌溉计划可以显着节省水、能源和劳动力。