Integrated optical sensor for NPK Nutrient of Soil detection

Soil is the most important medium for plant growth. The aim of this project is to develop a detection system for major nutrients of soil; Nitrogen, Phosphorus and Potassium (NPK) which consists of an optical sensor. The optical sensor is developed with two systems which are transmission system and detection system. The transmission system uses LED powered by Arduino UNO as a component to transmit light directly on the soil which contains nutrients in a transparent container. The detection system utilized two photodiodes developed with signal conditioner and an amplification circuit to detect the intensity of nutrients of the soil through the remaining light and to amplify the signal of light in terms of potential differences. The results show that the absorption response voltage of Nitrogen (N) is 32.0 V, the Phosphorus (P) is 4.6 V and Potassium (K) is 19.8 V. The presence and intensity of these nutrients are detected based on the rate of light absorbed by the nutrients in the soil, which is a high absorption of light by nutrients shows a high intensity of nutrients or vice versa.