## 1 Introduction  
The depletion of natural resources along with rapid climate change are weakening crop production ability, which is crucial for covering the nutritional needs of the constantly growing population on Earth. To tackle this problem, the quantity and quality of food could be improved by using components and technologies like innovative sensors, microprocessors, radios, automation, networking, and intelligent decision making [1; 2], along with more traditional ones, forming science policies known as Precision Agriculture (PA) [3]. The latter term means doing the right thing in the right place and at the right time, thus minimizing the input resources (such as arable land, agrochemicals, soil, and water) and maximizing outputs (such as crop yields and, finally, food). Among the pillars of PA is the Internet of Things (IoT). IoT, an emerging technology reshaping human activities and the way we interact with the environment, includes interconnected devices, hosting sensors, radio modules, and actuators, forming a functioning whole that gathers, interchanges, and responds to information [4]. PA, foreseeing the benefits from the adoption of IoT for faster, more precise, and less costly operations, embraces it as a facilitator for carrying out the collection of agri-field sensitive data and for transforming critical decisions into meaningful actions, thus fostering agri-automations and production. Several works highlight the key role of IoT technologies in agriculture, which is related to arable crop cultivation, orchard solutions, precision farming, greenhouse applications, and irrigation/fertilization management activities, thus forming areas of growing interest [5; 6; 7] for scientists and farmers. Utilizing environmental terms, soil productivity and water preservation prospects depend heavily on the extent to which the followed irrigation practices are optimized. In this context, the application of efficient soil monitoring techniques via IoT technologies is among the key factors being put toward a sustainable future, aligned with the United Nations (UN) Member States 2030 Agenda for Sustainable Development [8]. The incorporation of accurate and real-time soil monitoring is imperative in order to ensure that the exact amount of water will be applied at the right time and place [9]. These monitoring techniques, though, should tackle plenty of issues, like the diverse spatio-temporal conditions the electronic components will work in, the idiosyncrasies of the soil measurement instruments of interest, the degree of difficulty for equipment deployment, its expandability, and, clearly, its purchase, installation, and operation costs. Delving deeper into this subject, despite the plethora of research works discussing IoT functionality solutions for environmental purposes, most of them do not advance beyond a proof-of-concept-level description, or they focus mainly on sensor data analysis and presentation arrangements [10; 11; 12], addressing issues like powering and/or communication range coverage in a generic, non-optimal manner, e.g., requiring large-sized battery banks and solar panels per sensor node [11]. Clearly, just reporting the application-specific hardware and/or software settings for the delivery of the scientific data of interest is not enough, especially in cases when the reduction of the installation complexity and the increased life expectancy of the IoT platform deployment are of vital importance. In addition to this, for soil measurements, water rarely stays in one place for an extended period, thus making the precise calculation of its quantity difficult, which creates the need for the installation of numerous sensors to cover extended areas in an attempt to provide accurate real-time data. Consequently, the development and use of a low-cost and meticulously tailored sensor network multiplies the opportunities for scientists and farmers to have fluent, field-specific information and thus to make more optimal irrigation decisions.