EXPERIMENTAL CALIBRATION AND VALIDATION OF SOIL MOISTURE SENSORS FOR AN ARDUINO-BASED SMART IRRIGATION SYSTEM IN VINEYARDS

Climate change poses a significant challenge to global viticulture, as rising temperatures and increasing frequency of drought events intensify water scarcity and negatively affect grape yield and quality. In many wine-producing regions, particularly in Mediterranean climates, maintaining optimal soil moisture conditions has become increasingly difficult. In this context, the adoption of precision agriculture technologies and smart irrigation systems represents a key strategy for improving water-use efficiency and enhancing vineyard resilience. This study investigates the experimental calibration and validation of WATERMARK 200SS soil moisture sensors integrated into an Arduino Edge Control platform for vineyard monitoring and irrigation management applications. To improve the robustness of the monitoring system, soil moisture data were complemented with meteorological observations and measurements from a low-cost capacitive soil moisture sensor. The research methodology followed a dual-phase approach, consisting of laboratory calibration under controlled moisture conditions and subsequent field validation in an experimental vineyard. During the laboratory phase, sensors were tested across different predefined moisture gradients using a homogeneous sand substrate, allowing the evaluation of sensor sensitivity, response consistency, and stability under controlled conditions. The calibration process also enabled the characterization of the relationship between electrical resistance and soil water tension. In the field validation phase, sensor performance was assessed under real environmental conditions, including natural rainfall events and controlled irrigation inputs, to evaluate their practical applicability in dynamic vineyard conditions. The results demonstrate a strong agreement between laboratory and field measurements, confirming the reliability and robustness of the sensors across varying environmental conditions. The Watermark 200SS sensors were able to clearly distinguish between different soil moisture levels and showed high responsiveness to both irrigation and precipitation events through measurable variations in soil water tension. Compared to the low-cost capacitive sensor, the WATERMARK sensors exhibited more stable and consistent behavior, particularly under fluctuating moisture conditions. Overall, the findings confirm that WATERMARK 200SS sensors represent reliable tools for real-time soil moisture monitoring in viticulture. Their integration within an Arduino-based system provides a cost-effective, scalable, and efficient solution for data-driven irrigation management. This approach contributes to optimizing water use, reducing unnecessary irrigation, and supporting sustainable vineyard management under current and future climate change scenarios.