Enhancing the operation of the smart irri-kit system with capacitive probe sensor and nRF24 radio technology for efficient irrigation scheduling

Abstract

The Smart Irri-Kit system, a solar-powered automated irrigation solution, has shown promise in enhancing water use efficiency and crop yields. However, its effectiveness is restricted by limitations such as corrosion-prone resistive moisture sensors and wired connections, leading to signal losses and potential data corruption. This study generated a scalable solution to improve the Smart Irri-Kit's precision and flexibility by implementing capacitive probe sensors and nRF24L01 wireless transceivers. The redesigned system functions as a low-power wide area network (LPWAN), enabling long-range communication between field sensors and the solenoid valve actuator with minimal power consumption. The nRF24L01 transceivers were selected for their high data rates (up to 2 Mbps), low power usage, and built-in error detection and correction capabilities. The system consists of two main nodes: a sensor node and a valve node. The sensor node, equipped with an Arduino UNO microcontroller, displays sensor data on an LCD after converting it to volumetric water content using a calibration equation derived from the gravimetric method. The valve node, also using an Arduino UNO, controls water flow from an overhead tank to the drip irrigation system via a relay-connected solenoid valve. Both nodes are housed in waterproof acrylic cases with external ports for easy installation and reprogramming. Calibration and validation of the sensor node using the gravimetric method yielded an R² value of 0.8853, with an 87.6% correlation confirmed by a two-tailed t-test. The wireless communication achieved a range of 180 meters in clear line of sight and 150 meters with obstructions, without data loss. This study successfully enhances the Smart Irri-Kit's soil moisture sensing precision and flexibility, simplifying agricultural automation by overcoming the limitations of wired connections and traditional sensors.