An IoT-Based Soil Quality Monitoring and Automated Irrigation System for Open-Field Tomato Cultivation

Open-field tomato cultivation is vulnerable to environmental fluctuations, yet manual monitoring often leads to inaccurate decisions. This study aims to design and validate a low-cost Internet of Things (IoT)-based soil quality monitoring prototype, addressing the gap in accessible real-time alert systems for small-scale farming. The system integrates a NodeMCU ESP8266 with soil moisture, temperature (DS18B20), air humidity (DHT11), and pH sensors, visualized via Blynk and Telegram. Conducted over 14 days with nine experimental units across three soil media (clay, sandy, and humus), the study focused on technical prototype validation. Results indicate the system monitored moisture levels (43–47%) and temperatures (≈30.3 °C) with high reliability. Automated irrigation activated at ≈60% and deactivated at 80% moisture, maintaining an uptime of ≥95%. Sensor verification showed temperature deviations below ±1 °C. Unlike existing greenhouse-centric models, this work implements a multi-parameter sensing framework tailored for open-field conditions using affordable hardware. While this study successfully validates the prototype's operational stability and data synchronization, it is primarily a technical verification; further research is required to evaluate agronomic impacts such as yield and water-use efficiency.