Rancang Bangun Sistem Rekomendasi Pemupukan Tanaman Cabai Berbasis IOT Portable Terintegrasi Mobile

This study developed an Internet of Things (IoT)-based fertilizer recommendation system for red chili plants that operates on a local network. The development was motivated by the need to improve fertilization efficiency and
address the limited internet accessibility in plantation areas. The system was built using an ESP32 microcontroller integrated with an RS485 soil sensor to measure soil NPK nutrients, pH, and moisture in real time. All measurement data are transmitted directly to an Android smartphone via Bluetooth, allowing the system to operate entirely without relying on cellular or Wi-Fi networks.

The research findings show that the developed system is capable of reading NPK, pH, and soil moisture parameters, then transmitting the measurement data to an Android application via Bluetooth in a stable manner even without internet access. The application successfully processes sensor data using a local database and generates dosage recommendations for Urea, SP-36, and KCl fertilizers
according to plant age, based on the difference between soil nutrient conditions and the ideal requirements for red chili plants. Testing also demonstrated that all of the system's main functions—from the Bluetooth connection process, sensor
reading, local data storage, to the presentation of fertilization recommendations operate as designed. Thus, the system is able to provide fertilization recommendations in a portable manner and can be used in plantation areas without
internet network access.