Rice is the primary food source for millions of Asians and satisfies the most fundamental requirement for human survival. The paddy scarcity has heightened public awareness of the global food problem. Rice yield and quality are affected by various factors, including soil nutrients, irrigation, types of soil, and pests. This work proposed developing an Internet of Things (IoT) based mobile device for measuring soil nutrients in real-time. The proposed system consists of electrical conductivity (EC) and temperature sensors with TTGO T-Beam microcontroller and IoT connectivity. During experimental work, the results showed that the observed EC data near the calibration solution conductivity of 12.88mS/cm and 150mS/cm, which are less than 2% from the calibration solution's stated value. Furthermore, it is found that the measured EC value increases with temperature (linearly proportional). The study showed that the soil's EC of sensor node 1 at 5 cm depth without fertiliser is 1.04375mS/cm and with fertiliser is 3.86mS/cm, while at 10 cm depth without fertiliser is 0.65625mS/cm and with fertiliser is 420mS/cm. These investigations show that soil EC is directly linked to nutrient availability and soil depth.
