A fertilizer synergist and method of making same

Abstract

The application discloses a kind of fertilizer synergist and preparation method thereof, belong to agricultural fertilizer technical field.The synergist is by following weight parts of component composition: nanometer mineral efficiency component 10~20 parts, microbial metabolite 20~30 parts, functional polymer carrier 15~25 parts, compound enzyme preparation 5~10 parts, plant source active extract 5~10 parts, auxiliary agent 5~10 parts;Preparation method includes the preparation and compound process of each component respectively.The application can significantly improve the utilization rate of nitrogen, phosphorus, potassium and trace elements by the synergistic effect of various components, reduce fertilizer loss, improve soil structure and regulate soil microecological balance at the same time, has the advantages of high environmental safety, good stability, wide application range, etc., and can be widely applied to various crops and soil, has important economic and ecological benefits.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, specifically to a fertilizer synergist and its preparation method. Background Technology

[0002] With the increasing intensification of agriculture, the large-scale application of chemical fertilizers, while improving crop yields, has also brought about a series of problems such as low fertilizer utilization, soil compaction, acidification, and eutrophication of water bodies due to nutrient loss. Currently, there are many types of fertilizer synergists on the market, mainly including urease inhibitors, nitrification inhibitors, humic acids, amino acids, and microbial agents.

[0003] However, existing technologies have the following shortcomings: single-type synergists have limited functions; for example, urease inhibitors can only delay urea hydrolysis and cannot solve the problem of phosphorus fixation; microbial agents have poor survival stability in soil and are easily deactivated by environmental influences; some chemically synthesized synergists pose environmental risks, and long-term use may cause secondary pollution. In addition, most synergists have poor compatibility with fertilizers, and are prone to aggregation or decomposition, affecting the application effect.

[0004] Therefore, it is of great significance to develop a fertilizer synergist with multiple synergistic mechanisms, environmental friendliness, high stability and wide applicability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing fertilizer synergists, such as single function, poor synergy, insufficient stability and environmental risks, and to provide a fertilizer synergist and its preparation method. Through the synergistic effect of multiple functional components, it can improve the utilization rate of nitrogen, phosphorus, potassium and micronutrients, improve soil structure and regulate soil micro-ecological balance, and has good stability and environmental safety.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A fertilizer synergist is composed of the following components in parts by weight: 10-20 parts of nano-sized mineral synergist, 20-30 parts of microbial metabolites, 15-25 parts of functional polymer carrier, 5-10 parts of compound enzyme preparation, 5-10 parts of plant-derived active extract, and 5-10 parts of adjuvants.

[0008] The nanoscale mineral enhancement component includes 5-10 parts of nano-hydroxyapatite and 5-10 parts of nano-silica.

[0009] The microbial metabolites include 10-15 parts of Bacillus subtilis fermentation broth, 5-10 parts of phosphate-solubilizing bacteria fermentation broth, and 5 parts of actinomycete fermentation broth.

[0010] The functional polymer carrier is a carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer;

[0011] The compound enzyme preparation comprises 2-4 parts phytase, 1-2 parts urease inhibitor, 1-2 parts nitration inhibitor and 1-2 parts cellulase;

[0012] The plant-derived active extract includes 3-6 parts of seaweed extract and 2-4 parts of fulvic acid;

[0013] The additives include 2-3 parts of dispersant and 3-7 parts of stabilizer.

[0014] Nano-hydroxyapatite possesses a large specific surface area and excellent adsorption properties, enabling it to adsorb heavy metal ions in the soil, reducing their toxicity to crops. Simultaneously, it can undergo ion exchange reactions with insoluble phosphorus in the soil, converting phosphorus into a form absorbable by plants. Furthermore, it serves as an attachment carrier for microorganisms, promoting the growth and reproduction of beneficial microorganisms on its surface and enhancing the stability of the soil micro-ecosystem. Nano-silica can improve the physical structure of soil, increase soil porosity, and enhance soil aeration and water retention. Its surface silanol groups can complex with nutrient ions in fertilizers, reducing nutrient fixation and loss. It also strengthens plant cell walls, improving plant resistance to stresses such as drought and pests. This invention combines two nanomaterials to leverage their synergistic effects, providing a physicochemical basis for the efficient utilization of fertilizer nutrients and the optimization of the soil environment.

[0015] Bacillus subtilis produces various extracellular enzymes (protease, amylase, cellulase, etc.) during fermentation, which can decompose large organic molecules in the soil into smaller molecules such as amino acids and sugars, providing easily absorbed nutrients for plants and other microorganisms. Its metabolites can also inhibit the growth of pathogens in the soil, reducing plant diseases and promoting healthy plant growth through niche competition and the production of antibacterial substances. Phosphate-solubilizing bacteria secrete organic acids and phosphatases, which can dissolve insoluble phosphorus compounds in the soil, such as ferric phosphate, aluminum phosphate, and apatite, converting them into water-soluble phosphorus that plants can absorb, thus increasing the content of available phosphorus in the soil. They can also cooperate with other microorganisms to promote the cycling and utilization of phosphorus in the soil. Actinomycetes can produce various antibiotics and plant growth regulators, inhibiting the activity of harmful microorganisms in the soil and improving the soil microecological environment; on the other hand, they stimulate root growth and enhance the plant's ability to absorb nutrients. The fertilizer synergist of this invention uses the synergistic effects of three microbial metabolites to act on the soil and plants from multiple aspects, including nutrient supply, disease inhibition, and root promotion.

[0016] Carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymers possess excellent hydrophilicity and water retention properties, forming a three-dimensional network structure in the soil to adsorb and retain moisture, reduce water evaporation, and improve the soil's drought resistance. The numerous active groups on its molecular chain can interact with nutrient ions in fertilizers through ionic and hydrogen bonds, achieving slow nutrient release and extending the fertilizer's effective period. Furthermore, carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymers also effectively encapsulate and protect nanoscale mineral synergistic components, microbial metabolites, and complex enzyme preparations in fertilizer synergists, enhancing the stability and availability of each functional component in the soil.

[0017] Phytase hydrolyzes phytic acid and its salts, releasing phosphorus and increasing its availability in the soil. It also reduces the chelation of metal ions (such as zinc, iron, and calcium), making these micronutrients more readily absorbed and utilized by plants. Urease inhibitors slow down the hydrolysis of urea by inhibiting urease activity, reducing the volatilization loss of ammonia nitrogen and improving nitrogen fertilizer utilization. Nitrification inhibitors suppress the activity of nitrifying bacteria in the soil, preventing the conversion of ammonia nitrogen to nitrate nitrogen, reducing nitrate nitrogen leaching and nitrogen loss due to denitrification, prolonging nitrogen retention time in the soil, and improving nitrogen use efficiency. Cellulase decomposes cellulose-based organic matter in the soil, promoting mineralization, releasing nutrients, and improving soil structure, aeration, and permeability. This invention utilizes multiple enzyme preparations in combination, with each component working synergistically to promote the release, transformation, and preservation of fertilizer nutrients from different perspectives.

[0018] Seaweed extract is rich in various plant growth regulators (such as auxins, cytokinins, and gibberellins), seaweed polysaccharides, amino acids, and various mineral elements. It can stimulate plant growth, enhance photosynthesis, and improve plant stress resistance. It also has a certain water-retention effect, improving soil moisture conditions. Fulvic acid has strong ion exchange and complexing capabilities, forming stable complexes with nutrient ions in the soil, reducing nutrient fixation and loss, improving nutrient availability, promoting the growth and reproduction of soil microorganisms, improving the soil microecological environment, and enhancing soil fertility.

[0019] In the preparation of synergists, the addition of dispersants can effectively reduce the agglomeration of nano-sized mineral synergistic components and other particles, ensuring their uniform dispersion in the system, improving the stability and uniformity of the synergist, and ensuring that each functional component fully exerts its effect. Stabilizers can enhance the stability of microbial metabolites and compound enzyme preparations during storage and use, preventing them from being deactivated or deteriorated due to external environmental factors (such as temperature, humidity, and light), thus extending the shelf life of the synergist.

[0020] The components of this fertilizer synergist do not function independently, but rather achieve comprehensive synergistic effects through a complex synergistic mechanism. Nanoscale mineral synergistic components provide attachment sites for microorganisms; microbial metabolites improve soil microecology and promote nutrient transformation; functional polymer carriers control nutrient release and protect other components; compound enzyme preparations promote nutrient activation and preservation from multiple perspectives; plant-derived active extracts stimulate plant growth and enhance stress resistance; and adjuvants ensure stable dispersion of each component. These synergistic effects intertwine to construct a highly efficient, stable, and sustainable fertilizer synergist and soil improvement system, significantly improving fertilizer utilization, reducing fertilizer waste and environmental pollution, and achieving green and sustainable agricultural development.

[0021] As a further description of the above technical solution, the phosphate-solubilizing bacteria are preferably Bacillus megaterium; the actinomycetes are preferably Streptomyces.

[0022] As a further description of the above technical solution, the carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer is prepared by copolymerization of carboxymethyl chitosan with acrylic acid and acrylamide under the action of an initiator, wherein the degree of deacetylation of carboxymethyl chitosan is ≥90%.

[0023] As a further description of the above technical solution, the urease inhibitor is one or a mixture of two or more of N-butylthiophosphoric triamine (NBPT), phenylphosphoric diamine, and ammonium thiosulfate.

[0024] As a further description of the above technical solution, the nitration inhibitor is one or more of 2-chloro-6-(trichloromethyl)pyridine, dicyandiamide (DCD), and 3,4-dimethylpyrazole phosphate (DMPP).

[0025] As a further description of the above technical solution, the dispersant is preferably sodium lignosulfonate, and the stabilizer is preferably sorbitan monostearate (Span 60).

[0026] The present invention also provides a method for preparing the above-mentioned fertilizer synergist, comprising the following steps:

[0027] (1) Preparation of nanoscale mineral synergistic components: Nano hydroxyapatite and nano silica are mixed in proportion and then pulverized by airflow to a particle size of 50-100 nm.

[0028] (2) Preparation of microbial metabolites: Bacillus subtilis, phosphate-solubilizing bacteria and actinomycetes were inoculated into the optimized culture medium, and the supernatant was taken after fermentation and cultured and mixed in proportion.

[0029] (3) Preparation of functional polymer carriers: Carboxymethyl chitosan is copolymerized with acrylic acid and acrylamide under the action of an initiator to obtain a carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer;

[0030] (4) Preparation of compound enzyme preparation: Phytase, urease inhibitor, nitrification inhibitor and cellulase are mixed in proportion and then ground.

[0031] (5) Preparation of plant-derived active extracts: Mix seaweed extract with fulvic acid in a certain proportion;

[0032] (6) Synergist compound: Nanoscale mineral synergist components are added to a functional polymer carrier and dispersed by high-speed shearing. Then, microbial metabolites, compound enzyme preparations, plant-derived active extracts and adjuvants are added in sequence, and shearing and dispersion are continued. The fertilizer synergist is obtained by spray drying.

[0033] As a further description of the above technical solution, the optimized culture medium includes optimized culture medium for Bacillus subtilis, optimized culture medium for phosphate-solubilizing bacteria, and optimized culture medium for actinomycetes. The optimized culture medium for Bacillus subtilis comprises: glucose 15-25 g / L, yeast extract 8-12 g / L, peptone 10-15 g / L, sodium chloride 3-5 g / L, dipotassium hydrogen phosphate 2-3 g / L, magnesium sulfate 0.5-1 g / L, pH 7.0-7.2. The optimized culture medium for phosphate-solubilizing bacteria comprises: glucose 10-20 g / L, ammonium sulfate 2-4 g / L, sodium chloride 0.3-0.5 g / L, potassium chloride 0.3-0.5 g / L, ferrous sulfate 0.03-0.05 g / L, manganese sulfate 0.03-0.05 g / L, calcium carbonate 5-10 g / L, lecithin 2-5 g / L, pH 7.0-7.2. The pH of the optimized culture medium for actinomycetes is 7.0–7.5. The composition of this medium is as follows: soluble starch 20–30 g / L, potassium nitrate 1–3 g / L, dipotassium hydrogen phosphate 0.5–1 g / L, sodium chloride 0.5–1 g / L, magnesium sulfate 0.5–1 g / L, ferrous sulfate 0.01–0.03 g / L, calcium carbonate 3–5 g / L, pH 7.2–7.4. All the above culture media are prepared with deionized water and autoclaved at 121°C for 20 minutes before use. This optimized culture medium formulation can significantly improve the metabolic activity and secretion of functional components of the target microorganisms.

[0034] As a further description of the above technical solution, the degree of deacetylation of the carboxymethyl chitosan is ≥90%, the initiator is potassium sulfate, the amount of initiator is 0.5-1% of the total mass of the monomer, the copolymerization temperature is 60-70℃, and the reaction time is 3-4h.

[0035] As a further description of the above technical solution, the fulvic acid is extracted from weathered coal using an alkali dissolution and acid precipitation method, with a purity ≥90%.

[0036] As a further description of the above technical solution, the rotation speed of the high-speed shearing is 3000-5000 rpm; the inlet air temperature of the spray drying is controlled at 180-200℃.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This invention organically combines nanoscale mineral synergistic components, microbial metabolites, compound enzyme preparations, and plant-derived active extracts through a functional polymer carrier. The synergistic effect among these components not only inhibits urease and nitrifying bacteria activity, reducing nitrogen loss, but also alleviates the fixation of phosphorus, potassium, and trace elements through the adsorption-desorption effect of nanomaterials, improving their availability. Compared to single synergists, nitrogen utilization can be increased by 20-30%, and phosphorus utilization by 15-25%. Microbial metabolites and the functional polymer carrier provide nutrients and a habitat for soil microorganisms, promoting the reproduction of beneficial microorganisms, improving soil aggregate structure, and enhancing soil water and fertilizer retention capacity. Nano-hydroxyapatite can also adsorb heavy metal ions in the soil, reducing their bioavailability.

[0039] The components used in this invention are mostly natural extracts, microbial metabolites, and biodegradable polymers, leaving no residue and causing no pollution. This avoids the potential environmental risks posed by chemically synthesized synergists and meets the needs of green agricultural development. The functional polymer carrier has excellent encapsulation and protection effects on nanoparticles, enzyme preparations, and microbial metabolites, significantly improving the stability of the synergist during storage and application. Its effective period can reach more than 12 months, and it does not easily react chemically with various fertilizers, making it highly adaptable.

[0040] This invention can be widely applied to various crops such as grain crops, cash crops, vegetables, and fruit trees, and can achieve good results in different types of soil (acidic, neutral, and alkaline). Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0042] Example 1

[0043] A fertilizer synergist is composed of the following components in parts by weight: 5 parts nano-hydroxyapatite, 7 parts nano-silica, 10 parts Bacillus subtilis fermentation broth, 10 parts Bacillus megaterium fermentation broth, 5 parts Streptomyces fermentation broth, 15 parts carboxymethyl chitosan grafted acrylic acid-acrylamide copolymer, 2 parts phytase, 1 part N-butylthiophosphoric triamine, 1 part 3,4-dimethylpyrazole phosphate, 2 parts cellulase, 5 parts brown algae extract, 2 parts fulvic acid with a purity ≥90%, 3 parts sodium lignosulfonate, and 5 parts sorbitan monostearate.

[0044] Its preparation method includes the following steps:

[0045] (1) Preparation of nanoscale mineral synergistic components: Nanoscale hydroxyapatite was prepared by sol-gel method. Calcium nitrate and diammonium hydrogen phosphate were dissolved in deionized water at a Ca / P molar ratio of 1.67. The pH was adjusted to 9-10, and the mixture was stirred at 70℃ for 2.5 hours. After aging, centrifugation, washing, and drying, it was calcined at 600℃ for 2 hours. Nanoscale silica was prepared by gas phase method. Silicon tetrachloride was reacted with hydrogen and oxygen at high temperature, and nanoscale silica particles were collected. The two types of nanoparticles were mixed in proportion and pulverized by air jet milling to a particle size of 50-80 nm for later use.

[0046] (2) Preparation of microbial metabolites: Bacillus subtilis, Bacillus megaterium and Streptomyces were cultured separately. The three strains were inoculated into their respective optimized culture media and fermented at 30-35℃ and 180-200rpm for 48-72 hours. After fermentation, the supernatant was collected by centrifugation, which is the metabolite of each microorganism. The three strains were mixed in proportion for later use.

[0047] (3) Preparation of functional polymer carrier: Carboxymethyl chitosan with a degree of deacetylation ≥90% was dissolved in deionized water, and acrylic acid and acrylamide were added in a mass ratio of 1:1. Under nitrogen protection, potassium persulfate initiator of 0.8% of the total mass of monomers was added, and the reaction was carried out at 70°C for 4 hours to obtain carboxymethyl chitosan grafted acrylic acid-acrylamide copolymer, which was cooled and used for later use.

[0048] (4) Preparation of compound enzyme preparation: Phytase with enzyme activity ≥10000U / g, N-butylthiophosphoric triamine, 3,4-dimethylpyrazole phosphate and cellulase with enzyme activity ≥5000U / g are mixed in proportion, ground evenly, and set aside.

[0049] (5) Preparation of plant-derived active extracts: fulvic acid was extracted from weathered coal by alkaline dissolution and acid precipitation method, with a purity of ≥90%; fulvic acid and brown algae extract were mixed in proportion for later use.

[0050] (6) Combination of synergists: Nanoscale mineral synergists are added to functional polymer carriers and sheared and dispersed at 3000 rpm for 15 minutes in a high-speed shearing machine. Then, microbial metabolites, compound enzyme preparations, plant-derived active extracts and adjuvants are added in sequence and sheared and dispersed for another 30 minutes to obtain a uniform colloidal material. The colloidal material is spray-dried in a spray dryer with the inlet air temperature controlled at 200℃ and the outlet air temperature at 90℃ to obtain a powdered fertilizer synergist.

[0051] The fertilizer synergist of this embodiment was mixed with urea, diammonium phosphate, and potassium chloride (the synergist was added at 2% of the total fertilizer mass) and applied to wheat fields. The results showed that, compared with the control group without the synergist, wheat yield increased by 12.5%, soil organic matter content increased by 8.3%, nitrogen use efficiency increased by 22.1%, and phosphorus use efficiency increased by 16.8%.

[0052] Example 2

[0053] A fertilizer synergist is composed of the following components in parts by weight: 8 parts nano-hydroxyapatite, 5 parts nano-silica, 12 parts Bacillus subtilis fermentation broth, 8 parts Bacillus megaterium fermentation broth, 5 parts Streptomyces fermentation broth, 20 parts carboxymethyl chitosan grafted acrylic acid-acrylamide copolymer, 3 parts phytase, 1 part N-butylthiophosphoric triamine, 1 part diammonium phenyl phosphate, 1 part 2-chloro-6-(trichloromethyl)pyridine, 2 parts cellulase, 3 parts brown algae extract, 3 parts fulvic acid with a purity ≥90%, 2 parts sodium lignosulfonate, and 7 parts sorbitan monostearate.

[0054] The preparation method is the same as in Example 1, wherein the particle size of the nano-sized mineral synergist is controlled at 70-100 nm, the high-speed shearing speed is 4000 rpm, the spray drying inlet air temperature is 190°C, and the outlet air temperature is 90°C.

[0055] When the fertilizer synergist of this embodiment was mixed with compound fertilizer (addition amount 3%) and applied to tomato greenhouses, compared with the control group, the tomato yield increased by 15.2%, the vitamin C content increased by 10.3%, the available phosphorus content in the soil increased by 20.5%, and the soil bulk density decreased by 8.7%.

[0056] Example 3

[0057] A fertilizer synergist is composed of the following components in parts by weight: 10 parts nano-hydroxyapatite, 10 parts nano-silica, 15 parts Bacillus subtilis fermentation broth, 5 parts Bacillus megaterium fermentation broth, 5 parts Streptomyces fermentation broth, 25 parts carboxymethyl chitosan grafted acrylic acid-acrylamide copolymer, 4 parts phytase, 2 parts ammonium thiosulfate, 1 part 3,4-dimethylpyrazole phosphate, 1 part dicyandiamide, 1 part cellulase, 6 parts seaweed extract, 4 parts fulvic acid with a purity ≥90%, 2 parts sodium lignosulfonate, and 3 parts sorbitan monostearate.

[0058] The preparation method is the same as in Example 1, with a high-speed shearing speed of 5000 rpm, a spray drying inlet air temperature of 180°C, and an outlet air temperature of 80°C.

[0059] When the fertilizer synergist prepared in this embodiment was applied to rice fields in combination with urea (addition amount 2.5%), the rice grain filling rate increased by 8.6%, the thousand-grain weight increased by 2.3g, and the nitrogen loss rate decreased by 25.4%.

[0060] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A fertilizer synergist, characterized in that, It is composed of the following components in parts by weight: 10-20 parts of nano-sized mineral synergistic components, 20-30 parts of microbial metabolites, 15-25 parts of functional polymer carriers, 5-10 parts of compound enzyme preparations, 5-10 parts of plant-derived active extracts, and 5-10 parts of adjuvants. The nanoscale mineral enhancement component includes 5-10 parts of nano-hydroxyapatite and 5-10 parts of nano-silica. The microbial metabolites include 10-15 parts of Bacillus subtilis fermentation broth, 5-10 parts of phosphate-solubilizing bacteria fermentation broth, and 5 parts of actinomycete fermentation broth. The functional polymer carrier is a carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer; The compound enzyme preparation comprises 2-4 parts phytase, 1-2 parts urease inhibitor, 1-2 parts nitration inhibitor and 1-2 parts cellulase; The plant-derived active extract includes 3-6 parts of seaweed extract and 2-4 parts of fulvic acid; The additives include 2-3 parts of dispersant and 3-7 parts of stabilizer.

2. The fertilizer synergist according to claim 1, characterized in that: The phosphate-solubilizing bacteria are Bacillus megaterium; the actinomycetes are Streptomyces.

3. The fertilizer synergist according to claim 1, characterized in that: The carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer is prepared by copolymerization of carboxymethyl chitosan with acrylic acid and acrylamide under the action of an initiator, wherein the degree of deacetylation of carboxymethyl chitosan is ≥90%.

4. The fertilizer synergist according to claim 1, characterized in that: The urease inhibitor is one or a mixture of two or more of N-butylthiophosphoric triamine, phenylphosphoric diamine, and ammonium thiosulfate.

5. The fertilizer synergist according to claim 1, characterized in that: The nitration inhibitor is one or more of 2-chloro-6-(trichloromethyl)pyridine, dicyandiamide, and 3,4-dimethylpyrazole phosphate.

6. The fertilizer synergist according to claim 1, characterized in that: The dispersant is sodium lignosulfonate, and the stabilizer is sorbitan monostearate.

7. A method for preparing the fertilizer synergist according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of nanoscale mineral synergistic components: Nano hydroxyapatite and nano silica are mixed in proportion and then pulverized by airflow to a particle size of 50-100 nm. (2) Preparation of microbial metabolites: Bacillus subtilis, phosphate-solubilizing bacteria and actinomycetes were inoculated into the optimized culture medium, and the supernatant was taken after fermentation and cultured and mixed in proportion. (3) Preparation of functional polymer carriers: Carboxymethyl chitosan is copolymerized with acrylic acid and acrylamide under the action of an initiator to obtain a carboxymethyl chitosan-grafted acrylic acid-acrylamide copolymer; (4) Preparation of compound enzyme preparation: Phytase, urease inhibitor, nitrification inhibitor and cellulase are mixed in proportion and then ground. (5) Preparation of plant-derived active extracts: Mix seaweed extract with fulvic acid in a certain proportion; (6) Synergist compound: Nanoscale mineral synergist components are added to a functional polymer carrier and dispersed by high-speed shearing. Then, microbial metabolites, compound enzyme preparations, plant-derived active extracts and adjuvants are added in sequence, and shearing and dispersion are continued. The fertilizer synergist is obtained by spray drying.

8. The method for preparing the fertilizer synergist according to claim 7, characterized in that, The carboxymethyl chitosan has a degree of deacetylation ≥90%, the initiator is potassium sulfate, the amount of initiator is 0.5-1% of the total mass of monomers, the copolymerization temperature is 60-70℃, and the reaction time is 3-4h.

9. The method for preparing the fertilizer synergist according to claim 7, characterized in that, The fulvic acid is extracted from weathered coal using an alkali dissolution and acid precipitation method, with a purity of ≥90%.

10. The method for preparing the fertilizer synergist according to any one of claims 7 to 9, characterized in that: The high-speed shearing speed is 3000-5000 rpm; the inlet air temperature of the spray dryer is controlled at 180-200℃.