IoT-Based Smart Irrigation System Using DHT-11 and Soil Moisture Sensors with Real-Time Monitoring and Automated Water Pump Control

Abstract

Water scarcity and inefficient irrigation management present ongoing challenges for sustainable agricultural practice. This paper presents the design and implementation of an Internet of Things (IoT)-based smart irrigation system integrating DHT11 temperature-humidity sensors, capacitive soil moisture sensors, an ESP32 microcontroller, and automated water pump control with real-time remote monitoring capability. The system employs the Message Queuing Telemetry Transport (MQTT) protocol for secure, lightweight communication among the ESP32 firmware layer, a Golang backend server, and a ReactJS-based web dashboard, enabling remote supervision and actuation via standard web browsers. A threshold-based hysteresis control algorithm governs pump activation, triggering irrigation when soil moisture analog readings exceed 3000 (indicative of dry soil) and halting operation when readings fall below 2000 (indicative of adequately moist soil), effectively preventing rapid pump cycling. A fourteen-day evaluation demonstrated 99.29 percent MQTT message delivery reliability, a mean end-to-end latency of 555 ms, and 100 percent successful irrigation activations across eight distinct irrigation cycles with zero false-positive triggers. Sensor validation revealed a mean temperature deviation of 1.3 degrees Celsius, a humidity deviation of 3.2 percent relative humidity (RH), and a soil moisture correlation coefficient (R2) of 0.94 against gravimetric reference measurements. The system was assembled at a total hardware expenditure of under 30 United States Dollars (USD), positioning it as an accessible solution for small-scale and urban agricultural settings. Distinguishing features include integrated automated and manual control, Transport Layer Security (TLS)-secured MQTT communication, real-time Telegram-based notifications, and PostgreSQL-backed time-series data persistence.