HORIBA's nitrate ion meter test pen can be used to analyze fresh root sap, such as nitrogen content in onion plants, measure nitrate in lawn grass, and detect nutrient content in soil solutions and tomato plant sap, such as nitrate, potassium, and sodium ions. It can detect nitrate in soil to determine plant uptake of nitrogen. The required soil nitrate nitrogen (NO3-N) for special crops varies with different crops, but typically requires a concentration range of 10-50mg/kg. Can detect nitrate in hybrid Sudan grass and pearl chestnut. Regular monitoring of plant petioles, soil solutions, irrigation water, and drainage terminals for nitrate, potassium, and calcium not only achieves good yield and fruit quality, but also reduces fertilizer costs and mitigates environmental hazards.