Soil NPK sensor, also known as soil nutrient speed meter, is suitable for detecting the content of nitrogen, phosphorus and potassium in the soil. By detecting the content of nitrogen, phosphorus and potassium in the soil, the fertility of the soil can be judged and thus the soil condition can be easily and systematically assessed. The sensor is widely used in soil nitrogen, phosphorus and potassium detection, fine agriculture, forestry, soil research, geological exploration,···