Soil nutrition diagnosis is an important means to guide the scientific formula fertilization of longan. Through soil nutrient testing and plant nutrition diagnosis, the dynamic changes of soil nutrient supply status and tree demand and nutrient absorption can be grasped and tracked at any time. Information can improve the accuracy and credibility of soil testing and fertilization formula.

Reference values ??for suitable soil nutrient content indexes: organic matter 1.5%~2.0%, total nitrogen >0.05%, hydrolyzable nitrogen 7~15 mg per 100g soil, available phosphorus 10~30 mg per 100g soil , available potassium per 100 grams of soil, 50-120 mg, replacement calcium 150-1000 mg/kg, replacement magnesium 40-100 mg/kg, available iron 20-60 mg/kg, available zinc 2-8 mg /kg, replaceable manganese 1.5~5 mg/kg, easily reducible manganese 80~150 mg/kg, effective copper 1.2~5.0 mg/kg, water-soluble boron 0.4~1.1 mg/kg, effective molybdenum 0.2~0.35 mg /kilogram.