IOT-BASED AGRICULTURAL MONITORING SYSTEM
Abstract
This project presents the design and implementation of an Internet of Things (IoT)-based agricultural monitoring system aimed at addressing the inefficiencies of traditional subsistence farming practices in Nigeria. The system integrates an ESP32-WROOM microcontroller with a network of sensors including a DHT11 for atmospheric temperature and humidity, a DS18B20 for soil temperature, and a resistive soil moisture sensor that operates on the principle of inverse electrical resistance, where lower raw ADC values indicate wetter soil and higher values indicate drier soil.
Data is captured through a continuous 2-second sensing loop, with the ESP32 reading all sensors in real-time. The soil moisture sensor is powered only during measurement intervals to minimize electrolysis and prolong sensor life. The captured data drives an automated irrigation control logic based on dual-threshold hysteresis: the pump activates when soil moisture exceeds the DRY_THRESHOLD (2200 raw ADC value, indicating high resistance/dry soil) and deactivates when moisture falls below the WET_THRESHOLD (1600 raw ADC value, indicating low resistance/wet soil). A 20-second safety timeout prevents overwatering in case of sensor failure. All sensor readings and pump states are displayed locally on a 16×2 I2C LCD and transmitted via Wi-Fi every 3 minutes to a Google Apps Script API, which logs the data as timestamped entries in a Google Sheets database.
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