Design and Implementation of an IoT-Based Soil Moisture and pH Monitoring System with Telegram Notification

Abstract

The agricultural sector in Indonesia requires technological innovation to optimize land management, especially for environmentally sensitive commodities like spinach. Critical parameters such as soil moisture and acidity (pH) significantly affect the nutrient absorption process. This study aims to design and construct an automatic soil moisture and pH monitoring and control system based on the Internet of Things (IoT). The system is designed using an Arduino Uno microcontroller, ESP8266 WiFi module, YL-69 soil moisture sensor, and analog soil pH sensor. The actuators consist of a water pump, pH Up pump, and pH Down pump, controlled by relays based on ideal thresholds (60–80% for soil moisture and 6.0–7.0 for pH). The system features a remote monitoring interface via Blynk, interactive notifications via Telegram Bot, and offline data logging using a Micro SD. Calibration testing demonstrated the pH sensor has a coefficient of determination (R²) of 0.9122 with a maximum error of 0.6. A 7-day field test showed the system maintained an average soil moisture of 75.40% and a pH of 6.56. The physical growth of spinach plants in the automated control area proved to be much healthier compared to conventional maintenance methods.