Considering the technical aspects of planting crops, soil, fertilizer properties and fertilization methods, the following methods should be used when selecting compound fertilizers:

　　 1. Select compound fertilizer according to soil traits. The characteristics of the soil are different, and the selected compound fertilizers are different. For example, for the soils with slight alkalinity, low organic matter content and low nitrogen and phosphorus deficiency, it is generally necessary to use acidic nitrogen and phosphorus compound fertilizers, and it is advisable to purchase monoammonium phosphate or humic acid. Nitrogen, phosphorus and potassium compound fertilizers, nitrogen and phosphorus compound fertilizers; and for a few red clay or acid brown loam, red soil land, chemical basic compound fertilizers, such as diammonium phosphate, should be used. 2. Select compound fertilizer according to crop varieties. The demand for nutrients varies from crop to crop. Generally, NPK fertilizers are used for field crops; NPK ternary compound fertilizer should be used for wheat or rice high-yield ton grain fields; vegetables, especially fruits and vegetables, root vegetables and fruit trees, etc. Crops need more potassium, high-potassium and low-nitrogen NPK fertilizers should be used; legumes should use compound fertilizer with high phosphorus and potassium content; some cash crops should use ternary compound fertilizer suitable for local soil crops or Compound fertilizer containing trace elements. 3. Select compound fertilizer according to the length of crop growth period. The high-yield compound fertilizer with long growth period and the low-level compound fertilizer with short growth period. 4. Select compound fertilizer according to the nature of compound fertilizer. According to the national regulations, the effective nutrient content of standard compound fertilizer, the total concentration of high concentration of NPK ≥ 40% , the low concentration of ternary NPK ≥ 25% , the binary NPK ≥ 20% , and does not include trace elements and The amount of elements, water-soluble phosphorus content ≥ 40% , moisture content is less than 5% . When purchasing compound fertilizer, in addition to looking at the trademark and nutrient content, it is also necessary to pay attention to the manufacturer and the place of production. In addition, there are two kinds of potassium in the compound fertilizer, one is potassium chloride and the other is potassium sulfate. Where there is no " S " symbol on the composite fertilizer bag, the potassium contained in it is potassium chloride type potassium; if the fertilizer bag is marked with the " S " symbol, it is a compound fertilizer composed of potassium sulfate. 5. Select the compound fertilizer scientifically according to the fertilization method. In order to improve the fertilizer efficiency of the compound fertilizer, different application methods should be selected for different compound fertilizers. Granular compound fertilizer must be used for base fertilizer application. Powdered compound fertilizer should be used for topdressing application, and it should be noted that the water-soluble phosphorus content of phosphorus in compound fertilizer should be more than 40% . (China Pesticide and Fertilizer Network)