Development of a prototype device for automatic plant watering using a soil moisture detection system

Abstract

This research aims to develop a prototype automatic plant-watering system that operates based on soil moisture levels measured by a soil moisture sensor. The system is designed to reduce the users’ burden of plant care, particularly when regular watering is not possible. The prototype was tested using potted plants grown in loamy soil to evaluate the suitability of moisture thresholds for automatic control. The system consists of a soil moisture sensor, a microcontroller (e.g., Arduino or ESP32), and a water pump, all controlled automatically by predefined moisture thresholds. When soil moisture falls below the threshold, the system activates the water pump to irrigate the plant, and the pump stops once the moisture level reaches the upper limit. The experimental procedure included calibrating the sensor using the oven-dry method following ASTM D4959 and evaluating the prototype under real operating conditions for three consecutive days, with moisture data recorded every 30 minutes. The results show that the pump operated an average of three times per day, activating at moisture levels below approximately 12% and stopping at around 16%. Each activation delivered approximately 85–95 mL of water. Quantitative analysis indicates that the system reduced water usage by approximately 18–25% compared with manual watering while maintaining soil moisture within the desired range. The system also responded within 30 minutes of soil dryness detection. This prototype demonstrates strong potential for household or small-garden applications and can be further developed to support wireless networks or smartphone-based control for future smart farming implementations.