Introduction of compound fertilizer

What is the definition of NPK fertilizer?

So before we start, there are 3 concepts that is crucial for understanding the compound fertilizer:

• Compound fertilizer: Fertilizer with stated amounts of at least two of the three nutrients of nitrogen, phosphorus and potassium, a product made by chemical methods.
• Mixed fertilizer: Fertilizer with stated amounts of at least two of the three nutrients of nitrogen, phosphorus and potassium, a product made by physical mixing methods.
• Compound chemical fertilizer: Fertilizer with at least two nutrients in the indicated amounts among the three nutrients of nitrogen, phosphorus and potassium, a product made by chemical methods and/or physical processing.

What is general-purpose and special-purpose NPK fertilizers:

• General-purpose compound fertilizers are applicable to a wide range of regions and crops, but one or two of the effective nutrients may be excessive, causing waste; while other effective nutrients may be insufficient, becoming a limiting factor for increasing crop yields.
• Special compound fertilizers are only suitable for certain crops in a certain region and are highly targeted. Applying special compound fertilizers for specific crops such as wheat, rice, millet, beans, melons, vegetables, and fruits can maximize economic benefits from limited resources. , tobacco leaves, etc. There is a certain degree of specificity between classes and a certain degree of generality among similar classes.

What are the physical states of NPK fertilizers?

Compound fertilizers can be divided into two categories according to their physical state (formulation): 

• solid compound fertilizers and fluid (liquid) compound fertilizers. According to different processing methods and physical properties, solid compound fertilizers can be divided into granular compound fertilizers and powdery compound fertilizers, while fluid compound fertilizers can be divided into clear liquid compound fertilizers and suspension compound fertilizers. 
• There are many countries in the world that use granular compound fertilizers and fluid compound fertilizers. Therefore, the basic theory and application research on this type of fertilizer have received great attention and developed greatly.

Classification of NPK fertilizers with different concentrations.

Solid granular compound fertilizers are divided into three categories in China according to their total nutrient content concentration of nitrogen, phosphorus and potassium: high concentration, medium concentration and low concentration.

• High-concentration compound fertilizer is suitable for long-distance transportation. It is mainly formulated from high-concentration basic fertilizers (urea, ammonium phosphate, nitrate phosphate fertilizer, heavy calcium, ammonium chloride, potassium chloride) and lacks medium and trace elements such as Ca, Mg, S (except heavy calcium). If used alone for a long time, the soil aggregate structure and fertility will be destroyed; supplementary application or combined application of other fertilizers such as Ca, Mg, S, etc. will complicate the fertilization procedures.
• Medium and low concentration compound fertilizers are mainly prepared from ammonium sulfate, ammonium chloride, calcium chloride, calcium magnesium phosphate fertilizer, potassium chloride, potassium sulfate and potassium nitrate as basic fertilizers, supplemented by high concentration fertilizers. They can be prepared according to soil fertility. , crops require fertilizer according to the rules, and contain macro, medium and micro nutrients, which can ensure stable and high yield and simplify fertilization.
• Generally, export commodities are high-concentration compound fertilizers; those used domestically are medium and low-concentration compound fertilizers. For example, in 1976, Japan produced and used 1,089 brands of valley-type and peak-type low-concentration compound fertilizers, with a total volume of 331,000 tons, accounting for approximately 12% of the total compound fertilizer production output, all of which were used in Japan.

What are the advantages of compound fertilizers?

• Compound fertilizer has complete nutrients, reasonable combination of forms, strong pertinence, high nutrient utilization rate and good fertilizer efficiency. According to the fertilizer requirement pattern of planted crops, soil fertilizer supply performance and fertilizer effect, calculate the appropriate dosage ratio of nitrogen, phosphorus, potassium and medium and trace elements that need to be supplemented before planting the crop, and produce the corresponding brand of compound fertilizer, and then Supplemented by scientific fertilization methods, the amount of various nutrients required for the growth and reproduction of the crops can be met to achieve stable and high yields.
• Different crops often have certain requirements for nutrient forms. Since the composition of compound fertilizers, especially special compound fertilizers, is to match whatever nutrients are lacking during crop growth and growth, and the amount of nutrients that are lacking will be added. Put it in whatever form you like, so it is highly targeted, has high nutrient utilization and is effective.

A brief history, current situation and future of NPK fertilizer development：

• Compound fertilizer is based on the requirements of agricultural fertilization (such as: continuous increase in yield, continuous improvement of crop quality) and the achievements of the fertilizer industry itself (such as: progress in production technology, increasing scale of production equipment, sufficient various basic fertilizers, etc.) was born and developed on the basis of.
• The development, current situation and prospects of compound fertilizers in my country are: basic fertilizer research and factory production of compound fertilizers; production of general compound fertilizers; development of special compound fertilizers for formula fertilization; and development of biological compound fertilizers , several stages of promotion.
• The basic fertilizer research and factory construction and production stages of compound fertilizers have two obvious characteristics:
• First, built high, medium and low concentration production plants and micro-fertilizer production plants for single nutrients in NPK, such as urea, ammonium sulfate, ammonium chloride, calcium calcium, calcium magnesium phosphate fertilizer, potassium chloride, etc.;
• The second is to research and build industrial production plants for high-concentration compound fertilizers of NP and PK, such as ammonium phosphate, nitric acid phosphate fertilizer, etc., which laid a theoretical and material foundation for the development of compound fertilizers and gave birth to compound fertilizers.

Compound NPK fertilizer development in the 90’s

• With the above foundation in place, general-purpose compound fertilizers can be produced quickly. Its characteristics are: first, the blind application of NP, NPK, NK, and PK. No matter what kind of soil or what crops are planted, the proportion of NPK remains unchanged. After application, compared with the blank control, there is a certain increase, but its N, The utilization rate of P2O5 and K2O is not high and the waste is serious;
• Second, NP and NPK are combined with industrialized production, which solves many problems in the physical and chemical theory of mixing and production practice, so that general-purpose compound fertilizers can not only achieve NPK mixing in NP mixing production equipment, but also use basic fertilizers in specialized production equipment Products are produced in (disc, drum, twin-shaft, boiling, tower, extrusion and other granulation methods).

The future development of compound fertilizers：

• Special compound fertilizers were researched and developed in cooperation with agricultural soil and fertilizer workers when producers in the fertilizer industry noticed that farmers were blindly using single-component fertilizers and the value ratio of crop output to fertilizer inputs was gradually declining. Its first characteristic is the recognition that the relationship between crop yield, quality, efficiency and fertilization must conform to the “nutrient return (compensation) theory” and “minimum nutrient law” proposed by the German chemist Liebig in the late 19th century; it must conform to the European economist Du The diminishing return rate proposed by Ergo, Anderson and Mizelich must comply with the “law of comprehensive action of factors”, which brings fertilization technology into the gate of science.
• Mix based on the nutritional characteristics of crops and at the same time consider the fertilizer supply capacity of the soil. The mixed fertilizer is highly targeted for a certain crop, and the application area is wide but limited.

• Due to the variety of crops and the large differences in soil, temperature, rainfall, etc., there are many grades of special fertilizers for the same crop.

• It is necessary to consider the fertilizer supply capacity of the soil and meet the fertilizer requirements of the crops grown; it can not only increase the yield and income of the crops planted, but also continuously improve and improve the soil aggregate structure and fertility, and combine land cultivation with land use.

• Applying sufficient amounts of organic fertilizer before planting crops can fertilize the soil. At the same time, the available nutrients (macro, medium, and trace elements) in the soil are measured, and the mixture is mixed according to the fertilizer requirements of the crops, what nutrients are missing, what nutrients are missing, what forms of nutrients are missing, and what is missing is supplemented. Formulated into compound fertilizer.