Compound fertilizer has the advantages of high nutrient content, less auxiliary components and good physical properties. It plays an important role in balanced fertilization, improving fertilizer utilization rate and promoting high yield and stable yield of crops. But it also has some shortcomings, such as its nutrient ratio is always fixed, and the types, quantities and proportions of nutrients required for different soils and different crops are diverse. Therefore, it is best to conduct soil testing before use to understand the texture and nutritional status of the soil in the field, and also pay attention to the application with unit fertilizer to get better results.

The compound fertilizer has a long effect, and it is advisable to do a large amount of base fertilizer test. It is indicated that both the binary and the ternary compound fertilizer are based on the basic application. This is because the compound fertilizer contains various nutrients such as nitrogen, phosphorus and potassium. The crop is particularly sensitive to phosphorus and potassium in the early stage, and it is required that the phosphorus and potassium fertilizers should be used as the base fertilizer. Compound fertilizer should not be used for seedling fertilizer and mid-late fertilizer to prevent greed. The decomposition of compound fertilizer is slow. For crops that use compound fertilizer as base fertilizer during sowing, according to the fertilizer requirement of different crops, quick-acting nitrogen fertilizer should be supplemented in time for topdressing to meet the nutritional needs of crops.

The concentration of compound fertilizer is quite different, so we should pay attention to the selection of suitable concentration. At present, most compound fertilizers are configured according to the average nutrient status of soil types in a certain area and the proportion of crops required for fertilizer. There are high, medium and low concentration series of compound fertilizers on the market. Generally, the total concentration of low concentration total nutrients is between 25% and 30% , the medium concentration is between 30% and 40% , and the high concentration is above 40% . It is necessary to use economical and efficient compound fertilizers due to different regions, soils and crops. Generally, high-concentration compound fertilizer is used in economic crops, with excellent quality, less residue and high utilization rate. The concentration of compound fertilizer is high, and it is necessary to avoid direct contact between seeds and fertilizer. The compound fertilizer has a high nutrient content. If it is in direct contact with the seed or seedling roots, it will affect the emergence of seedlings and even the burning of seedlings and rotten roots. Sowing, fertilizing seed and should, compound fertilizer strip away 5--10 cm.

The ratio of compound fertilizer to raw material should be different. It should be noted that the use range of nutrient components is different from that of different brands and different concentrations of compound fertilizer. The production should be selected according to soil type and crop type. Nitrate-containing compound fertilizer should not be used in leafy vegetables and paddy fields; compound fertilizer containing ammonium ions should not be applied on saline-alkali soil; compound fertilizer containing potassium chloride or chloride ion should not be used on chlorine-free crops or saline-alkali soil; Compound fertilizer containing potassium sulfate is not suitable for application in paddy fields and acidic soils. Otherwise, it will reduce fertilizer efficiency and even poison crops. The compound fertilizer contains two or more kinds of large elements, and the nitrogen table is easily volatile or lost with rainwater. Phosphorus and potassium are easily fixed by the soil, especially phosphorus is less mobile in the soil, and the surface is not easily absorbed by the roots of the crop. It is also not conducive to the deep rooting of the roots. In the case of drought, the fertilizer cannot be dissolved and the fertilizer effect is worse. Therefore, the compound fertilizer should be applied deep.