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Soil testing and fertilization is a formula fertilization technique developed on the basis of chemical determination of soil fertility. Through the determination of soil available nutrients, determine the degree of soil nutrient abundance, propose fertilizer recommendations. The advantages of this method are simple, fast, and inexpensive, can be carried out year after year, and can serve every plot, playing a micro-guidance role in formula fertilization. However, the method of determination is different, and effective nutrient indicators are also different. At the same time, the fertility indicators between different soils and different crop species are not comparable, and they do not have macroscopic guidance and regulation functions. The checksum correction of the parameters also needs constant improvement. Nowadays, the nutrient balance method and the soil fertility index method that are used more often have been developed on this basis.
Fertilizer effect function method is based on fertilizer field experiments and biostatistics. The production of crops is regarded as the production function of fertilizers, and fertilizer effect tests are set up on representative plots to obtain the benefit function of the crop yield corresponding to each fertilization amount (or combination). Therefore, in order to obtain more accurate results, this method requires a longer period and high test costs. At the same time, due to the climate differences between years, its reproducibility is poor. It is mainly used for macro guidance.
Crop nutrition diagnosis method is based on plant nutrition chemistry fertilization technology. The disadvantage of this method is that it can only qualitatively reflect the level of nutrients in crop plants, and cannot accurately determine the amount of fertilizer that needs to be applied, because there are many factors that affect the absorption and utilization of nutrients by crops.
Basic Formula for Soil Testing and Formula Fertilization (Nutrient Balance Method)
The nutrient balance method is a method to achieve the balance of nutrient supply and demand between crops and soil, and to obtain the amount of fertilizer needed to achieve planned production based on the difference between the amount of fertilizer required by the crop and the soil supply. The formula for the nutrient balance method is:
Fertilizing amount of certain nutrients = target yield of crops Needed fertilizer amount - soil supplying amount of fertilizer/fertilizer nutrient content fertilizer utilization rate
In the formula, the target crop yield needs the amount of fertilizer = the biological output of the crop. The average content of a certain nutrient in the crop body; the amount of soil fertilizer is calculated from the nutrient absorption of the crop when no such nutrients are applied; the fertilizer utilization rate is based on the plot. The results of field trials were calculated.
From the above formula, we can see that if we want to grasp the nutrient balance method of formula fertilization technology, we need to grasp the crop needs fertilizer, soil fertilizer supply, fertilizer utilization, nutrient content of fertilizer and other relevant parameters.
Three characteristics of formula fertilization
Formula fertilization is based on the law of crop demand fertilizer, soil fertilizer characteristics and fertilizer effects, under the conditions of organic fertilizer, put forward the appropriate amount and proportion of nitrogen, phosphorus, potassium and trace fertilizer and their corresponding fertilization techniques. At present, there are many methods of formula fertilization applied throughout the country. The basic principles can be divided into three systems: soil fertilization method, fertilizer effect function method and crop nutrition diagnosis method.