Crop yield is directly affected by the plant macronutrients, mainly Nitrogen (N) and Phosphorous (P) status. For rice crop, the growers must determine when to apply N fertilizer as the nitrogen deficiency leads to lower yield and economic lost. Chlorophyll meter and leaf color chart (LCC) have been used for years to find the correlation between the rice’s chlorophyll and its nitrogen use, hence the demand of N in the field during growing cycle. LCC is more preferred as it is the least expensive but the technique is not accurate and the readings are not consistent. This work develops a very simple sensor device which uses extremely low-cost, off-the-shelf optical components to replace the LCC. The heart of the device is the AS7262 6-Channel Visible Spectral ID Device made by AMS. The sensor prototype was built and tested. Preliminary results show a promising device which is very low cost, simple, low maintenance, and easy to use in the field to support rice growers to determine the need for nitrogen in the growing cycle.