The amounts of nitrogen (N), phosphorus (P), and potassium (K) in the soil must be measured in order to calculate the amount of fertilizer supplementation required to increase crop fertility. Enhancing soil quality through nutrient optimization raises agricultural yields. A fiber optic-based color sensor has been created for this investigation in order to evaluate soil sample N, P, and K contents. The method makes use of colorimetric analysis, which is based on the idea that soil solutions absorb light. Nutrient levels are classified by the sensor as high, medium, low, or nonexistent. When a sensor probe is combined with the right signal conditioning circuits, it may detect nutrient deficits and precisely apply fertilizer to the soil to suit its demands.