A fertilizer synergistic additive, its preparation method and application

Abstract

The present application relates to a kind of chemical fertilizer synergistic additive and its preparation method and application, belong to the field of chemical fertilizer additive.The synergist is composed of water-soluble silicate, polyacrylamide, sodium naphthaleneacetate, sodium indoleacetate, modified biochar and composite microbial inoculant.The inoculant is pre-loaded in the porous structure of modified biochar, and then granulated with polyacrylamide etc., to build a physical-chemical-biological synergistic system.The reticular structure of polyacrylamide and the porous structure of biochar form double fixation, to store nutrients and microorganisms;Bacillus mucilaginosus produces acid to promote silicon dissolution, and Bacillus amyloliquefaciens produces antibiotics to inhibit disease;Plant growth regulator promotes root, and root exudates and microorganisms mutual feed.The present application significantly increases yield under the condition of reducing the amount of chemical fertilizer, and improves soil, with the dual effect of increasing yield and improving soil.

Description

Technical Field

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

[0002] Chemical fertilizers are indispensable production materials in modern agriculture, playing a vital role in ensuring grain yields. However, the long-term use of chemical fertilizers alone has led to increasingly prominent problems such as soil compaction, declining organic matter, and imbalanced microbial flora. Furthermore, the utilization rate of existing chemical fertilizers in the current season is generally low, with nitrogen fertilizer utilization at only 30%-35% and phosphorus fertilizer utilization at less than 20%. A large amount of nutrients are lost through volatilization, leaching, and fixation, resulting not only in resource waste and increased planting costs but also in environmental problems such as eutrophication of water bodies. Therefore, how to maintain or increase crop yields while reducing fertilizer use has become a pressing technical challenge for sustainable agricultural development.

[0003] To address the aforementioned problems, various fertilizer synergists have emerged in the prior art. For example, CN110172001A discloses an organosilicon functional fertilizer synergist, which is composed of water-soluble silicates, polyacrylamide, and... Composed of sodium naphthaleneacetate and sodium indoleacetate, this technology uses the network structure of polyacrylamide to prevent nutrient loss and combines with plant growth regulators to promote growth and development, thus improving fertilizer utilization to some extent. However, this technical solution mainly focuses on physical fertilizer retention and chemical regulation, failing to address the regulation and improvement of soil microbial communities. Its effects on long-term nutrient supply and overall improvement of the soil ecosystem are limited. Furthermore, its growth-promoting effect on crops relies primarily on exogenous regulators, lacking synergistic interaction with soil microorganisms, making it difficult to achieve sustainable soil fertility improvement and crop yield increase. Summary of the Invention

[0004] In order to solve the problems of the prior art, the present invention provides a fertilizer enhancement additive, its preparation method and application.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: Firstly, a fertilizer enhancement additive, composed of the following raw materials in parts by weight: 30-50 parts of water-soluble silicate 20-40 parts of polyacrylamide Sodium naphthaleneacetate 2-15 parts Sodium indoleacetate 2-10 parts 10-30 parts of modified biochar 1 to 10 parts of compound microbial inoculant.

[0006] Fertilizer synergists feature a precisely synergistic design in their raw material composition. Water-soluble silicates provide crops with silicon, promoting photosynthesis and cell wall silicification, thus enhancing stress resistance; polyacrylamide, after absorbing water and swelling, forms a three-dimensional network structure in the soil, effectively retaining nutrients and preventing loss. Sodium naphthaleneacetate and sodium indoleacetate, as plant growth regulators, synergistically promote root development and nutrient absorption. Building upon this, the innovatively introduced modified biochar possesses a rich microporous structure and surface functional groups. On one hand, it acts as a "protective chamber" for microorganisms, providing colonization sites and carbon sources for the compound microbial agent. On the other hand, through its ion adsorption capacity, it forms a "mesh-pore dual retention system" with the network structure of polyacrylamide, achieving a dual fertilizer retention effect through physical interception and chemical adsorption of fertilizer nutrients. In the compound microbial agent, *Bacillus amyloliquefaciens* secretes antibiotics to inhibit soil-borne diseases, while *Bacillus mucilaginosus* decomposes silicate minerals to release potassium and silicon. Their metabolites form a positive feedback loop of "root-promoting bacteria-bacteria-promoting root" with plant root exudates. The five components achieve system-level synergy in three dimensions: physical structure, chemical transformation, and biological activation, realizing an integrated synergistic effect of "fertilizer retention, growth promotion, and soil improvement."

[0007] In one specific embodiment of the first aspect, the modified biochar is acid-modified or humic acid-modified biochar, which is obtained by pyrolysis of agricultural waste at 400-600°C.

[0008] In one specific embodiment of the first aspect, the acid is one or more of phosphoric acid, sulfuric acid, or hydrochloric acid, and the modification method is to soak the biochar in an acid solution of 0.5 to 2 mol / L for 12 to 24 hours, and then wash and dry it.

[0009] In one specific embodiment of the first aspect, the compound microbial agent comprises Bacillus amyloliquefaciens and Bacillus mucilaginosus, with an effective viable count of... .

[0010] In one specific embodiment of the first aspect, the water-soluble silicate is sodium silicate and / or potassium silicate.

[0011] Secondly, a method for preparing a fertilizer enhancement additive includes the following steps: S1: The composite microbial agent is loaded onto modified biochar and dried at low temperature to obtain the biochar agent carrier; S2: Water-soluble silicates, polyacrylamide, Sodium naphthaleneacetate and sodium indoleacetate are pulverized separately, mixed evenly, and the basic synergistic powder is obtained. S3: Mix the carrier obtained in step S1 with the powder obtained in step S2, add a binder to granulate, dry and sieve to obtain granular fertilizer enhancer.

[0012] The preparation method, employing a "pre-loading then mixing" process sequence, lays the material foundation for the synergistic effect of multiple components. Step S1 involves pre-loading the composite microbial agent into the porous structure of modified biochar and drying it at a low temperature of 30–40°C. This ensures maximum retention of microbial activity and allows the agent to firmly adhere to the pores and surface of the biochar, forming a "biochar agent carrier." This pre-loading process is crucial: the microporous structure of the biochar provides physical protection for microorganisms, shielding them from predation by native bacteria and adverse environmental stresses in the soil, significantly improving survival rate and colonization ability; simultaneously, the organic acid functional groups enriched on the surface of the biochar provide an initial carbon source for microbial metabolism. Step S2 involves adding water-soluble silicates, polyacrylamide, and... Sodium naphthaleneacetate and sodium indoleacetate are pulverized separately and then mixed to ensure uniform dispersion of each chemical component. In step S3, the carrier and powder are mixed and granulated, so that the biochar particles loaded with microbial agents are tightly combined with the synergistic powder to form a microscopic composite unit of "microorganism-biochar-chemical synergist". This process design of "microbial agent loading first and then composite" ensures that each component can be released synchronously and synergistically in situ in the soil after application, providing a feasible physical basis for subsequent linkage mechanisms such as physical fixation, biological activation, and chemical growth promotion.

[0013] In one specific embodiment of the second aspect, the mass ratio of the microbial agent to the modified biochar in step S1 is 1:(5-10), and the drying temperature is 30-40°C.

[0014] In one specific embodiment of the second aspect, the binder in step S3 is starch paste, polyvinyl alcohol, or water, and the amount used is 5% to 10% of the total mass of the material.

[0015] Thirdly, the application of a fertilizer synergist is described, in which the fertilizer synergist is mixed with fertilizer at a mass ratio of (1-10):100 and then applied.

[0016] When fertilizer synergists are mixed with fertilizers, they activate a series of dynamic linkage mechanisms in the rhizosphere microenvironment of the soil. After application, polyacrylamide rapidly absorbs water and swells to form a three-dimensional network structure, immobilizing biochar particles loaded with microbial agents and fertilizer nutrients in the crop rhizosphere, creating a "nutrient-microbe enrichment zone." The porous structure of the biochar protects microorganisms from colonizing and multiplying in this area. *Bacillus amyloliquefaciens* secretes lipopeptide antibiotics to form an antibacterial zone in the rhizosphere, inhibiting soil-borne pathogens; *Bacillus mucilaginosus* secretes organic acids, which on the one hand decompose soil minerals to release potassium and silicon, and on the other hand promote the slow dissociation of water-soluble silicates, synchronizing the silicon release curve with crop needs. Simultaneously… Sodium naphthaleneacetate and sodium indoleacetate stimulate extensive root development in crops. The organic carbon source secreted by the roots becomes "food" for microorganisms, and the auxin-like substances produced by microbial metabolism further promote root growth, forming a positive feedback loop of "medicine-promoted roots - roots nourishing microorganisms - microorganisms promoting roots - microorganisms preventing diseases." Nutrients adsorbed by biochar are desorbed and released when root absorption leads to a decrease in rhizosphere concentration, forming a dual slow-release supply with the network retention of polyacrylamide. Ultimately, this achieves multiple effects of "reduced fertilizer use - increased yield - improved soil," resulting in significant yield increases even with a 40% reduction in fertilizer use.

[0017] In one specific embodiment of the third aspect, the fertilizer is a nitrogen fertilizer, phosphate fertilizer, potassium fertilizer, or compound fertilizer.

[0018] The beneficial effects of this invention are as follows: 1. This invention addresses the technical shortcomings of existing fertilizer synergists, such as limited functionality, lack of long-lasting effects, and inability to systematically improve the soil micro-ecological environment. It builds upon existing technologies using "water-soluble silicate + polyacrylamide"... Based on the quaternary compound system of sodium naphthaleneacetate and sodium indoleacetate, modified biochar and composite microbial agents were introduced. Through a specific process of pre-loading the microbial agents onto the biochar, a synergistic system integrating physical retention, microbial activation, and chemical growth promotion was constructed. In this system, the network structure of polyacrylamide and the porous structure of biochar form a dual network-pore retention mechanism, achieving synergistic retention of fertilizer nutrients and microbial agents. Organic acids produced by Bacillus mucilaginosus metabolism promote the dissolution of silicate minerals, while antibiotics produced by Bacillus amyloliquefaciens metabolism form an antibacterial zone in the rhizosphere, achieving a synergistic effect of nutrient activation and disease resistance promotion. Sodium naphthaleneacetate and sodium indoleacetate stimulate root growth and development. Root exudates provide carbon sources for microorganisms, and auxin-like substances produced by microbial metabolism in turn promote root growth, forming a positive feedback loop of root-microbe interaction. The above five-layer linkage mechanism is mutually coupled and progressive, forming a system-level closed loop in which physical structure supports biological activities, biological activities promote chemical transformation, chemical transformation provides feedback to crop growth, and crop growth improves the soil environment.

[0019] 2. This invention has the following technical advantages over existing technologies: First, the porous structure of biochar provides physical protection for microorganisms, significantly improving the survival rate and colonization ability of functional strains in the soil; the adsorption and enrichment of microbial metabolites (organic acids, antibiotics) by the functional groups on the surface of biochar proliferates and prolongs their duration of action. Second, through the synergistic ratio of Bacillus mucilaginosus and Bacillus amyloliquefaciens, a dual functional balance of silicon and potassium activation and soil-borne disease inhibition is achieved, constructing an integrated system of biological control and nutrient supply in the rhizosphere microdomain. Third, through the mesh-pore dual structure formed by polyacrylamide and biochar, a dual fertilizer retention mechanism of chemical adsorption and physical interception of fertilizer nutrients is achieved, significantly reducing nutrient leaching loss. Finally, through the coupling of root regulation mechanisms and microbial activation mechanisms, a positive feedback loop is formed, in which exogenous hormones promote root growth, root exudates nourish microorganisms, and microorganisms produce endogenous hormones to further promote root growth, thereby enhancing the crop's ability to actively acquire soil nutrients. This invention achieves an upgrade from single chemical enhancement to a three-in-one system regulation of physical, chemical and biological processes, an expansion from short-term rapid effects to a long-term mechanism for increasing yield in the current year and continuously improving soil, and a transformation from passive nutrient supplementation to active regulation of root-fungus-soil interactions. It has significant synergistic effects in reducing fertilizer use, increasing crop yield, improving soil, and utilizing agricultural waste resources. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] A fertilizer enhancement additive, its preparation method, and its application.

[0022] I. Overview of the Invention and Construction of the Collaborative System This invention provides a biochar-based microbial compound fertilizer synergist with multiple dynamic linkage effects. Its core concept lies in: building upon existing technologies such as "water-soluble silicate + polyacrylamide"... Based on the quaternary compound system of sodium naphthaleneacetate and sodium indoleacetate, modified biochar and composite microbial agents are introduced. Through a specific process, the microbial agents are pre-loaded into the porous structure of biochar to construct a synergistic system integrating "physical retention, chemical growth promotion, and biological activation." This system achieves system-level synergy among components through a five-level dynamic linkage mechanism, ultimately achieving multiple goals of "reduced fertilizer use, increased crop yield, and improved soil."

[0023] II. Mechanism of Synergistic Effect of Multiple Components (I) Physical fixation-biological colonization linkage mechanism Mechanism of action: Polyacrylamide is a water-soluble polymer that, when applied to the soil, absorbs water and swells to form a three-dimensional network gel structure. This network structure, on the one hand, physically traps fertilizer nutrients (ammonium ions, potassium ions, etc.) within the mesh, preventing them from being lost with water; on the other hand, it encapsulates biochar particles loaded with microbial agents in the rhizosphere, forming a "nutrient-microbe enrichment zone." Modified biochar possesses a well-developed microporous structure (pore size distribution 2-50 nm) and a large specific surface area (up to 300-500 m²). 2 In the preparation process of this invention, the composite microbial agent is pre-loaded into the pores and surface of biochar, making the biochar a "protective cabin" for the microorganisms. Studies have shown that using biochar as a carrier can extend the survival period of beneficial microorganisms to more than one year.

[0024] Dynamic interaction: The network structure formed by polyacrylamide fixes the biochar particles loaded with microorganisms in the rhizosphere, preventing the microorganisms from being lost with water; the microporous structure of biochar provides physical protection for the microorganisms, protecting them from phagocytosis by soil native bacteria and harm from adverse environments (such as drought, acid and alkaline stress). Together, they form a dual retention system of "physical network locking in nutrients, microporous structure protecting microorganisms." Experimental data show that using the "biochar pre-loading + polyacrylamide retention" technology of this invention, the survival rate of microorganisms in the soil is more than 3 times higher than that of directly applying microbial agents.

[0025] (II) Microbial activation-chemical dissolution linkage mechanism Mechanism of Action: The Bacillus mucilaginosus (also known as silicate bacteria) selected in this invention possesses unique metabolic functions, capable of secreting organic acids (oxalic acid, citric acid, tartaric acid, etc.) and extracellular polysaccharides. These organic acids, on the one hand, decompose native silicate minerals in the soil, releasing nutrients such as potassium and silicon; on the other hand, they promote the slow dissociation of the water-soluble silicates added in this invention, resulting in a smoother and longer-lasting silicon release curve, avoiding the problem of fixation by the soil after a single release. The modified biochar surface is rich in oxygen-containing functional groups such as carboxyl and hydroxyl groups, which can adsorb organic acids produced by microbial metabolism, forming a localized "slightly acidic zone" around the biochar particles (pH can be 0.5-1.0 units lower than the surrounding soil).

[0026] Dynamic interaction: After *Bacillus amyloliquefaciens* colonizes the pores of biochar, the organic acids produced by its metabolism are adsorbed and enriched by the functional groups on the biochar surface, forming a continuously acting "micro-reactor" at the biochar-soil interface. This reactor continuously acts on the surrounding silicate particles, achieving the slow release of silicon and potassium. Simultaneously, enzymes and antibiotics produced by *Bacillus amyloliquefaciens* metabolism are also adsorbed by biochar, forming a "reservoir" of functional substances and prolonging their action time. Studies have shown that when biochar is used in combination with phosphate-solubilizing bacteria, the phosphorus absorption rate of corn can be increased by 58%.

[0027] (III) Root regulation-rhizosphere feedback linkage mechanism Mechanism of action: Sodium naphthaleneacetate (NAA) and sodium indoleacetate (IGA) are two potent plant growth regulators that synergistically promote crop root growth and development, particularly the proliferation of lateral roots and root hairs. Once the root system is well-developed, the secretion of organic carbon sources (sugars, organic acids, amino acids, etc.) increases significantly. These root exudates are the primary energy source for rhizosphere microorganisms. *Bacillus amyloliquefaciens* and *Bacillus mucilaginosus* utilize root exudates to multiply rapidly. The auxin-like substances (such as IGA and gibberellins) and siderophores produced during their metabolism further stimulate root growth.

[0028] Dynamic linkage performance: This invention constructs a positive feedback loop of "exogenous hormones promoting root growth - root exudates nourishing bacteria - bacteria producing endogenous hormones to further promote root growth". Specifically, Sodium naphthaleneacetate and sodium indoleacetate act as "initiating signals" to stimulate rapid root growth; root exudates serve as "energy fuel" to support microbial reproduction; and endogenous hormones such as indoleacetic acid produced by microbial metabolism act as "continuous signals" to maintain root vitality. This positive feedback loop increases root biomass by more than 30% and enhances root vitality by 25%-40%.

[0029] (iv) Disease resistance and growth promotion-metabolic regulation linkage mechanism Mechanism of action: Bacillus amyloliquefaciens is a typical rhizosphere growth-promoting and biocontrol bacterium that produces lipopeptide antibiotics (such as surfactants and iturobacillus), chitinases, and glucanases, among other antibacterial substances. These substances can lyse the cell walls of soil-borne pathogenic fungi (such as Fusarium, Rhizoctonia, and Phytophthora), inhibiting the occurrence of soil-borne diseases. Modified biochar, acting as an adsorbent carrier, can adsorb these antibacterial substances, prolonging their residence time in the rhizosphere and forming a dual physical-biochemical barrier.

[0030] Dynamic linkage: Antibiotics adsorbed by biochar are slowly released around the rhizosphere, forming a continuously effective "antibacterial zone." Experiments show that using the "biochar-loaded microbial agent" technology of this invention, the half-life of antibiotics produced by Bacillus amyloliquefaciens in the soil is extended by 2-3 times, and the inhibitory effect on pathogens is improved by more than 40%. At the same time, healthy roots can continuously secrete organic matter to supply microorganisms, maintain their biocontrol activity, and form a virtuous cycle of "microbes protecting roots - roots nourishing microbes."

[0031] (V) Ion adsorption-slow release supply linkage mechanism Mechanism of action: Modified biochar has a high cation exchange capacity (up to 50-150 cmol / kg), enabling it to firmly capture cationic nutrients such as ammonium and potassium ions through electrostatic adsorption. The gel network formed by polyacrylamide then physically retains the nutrient-containing soil solution within the grid. Together, they form a dual fertilizer retention mechanism of "chemical adsorption + physical retention".

[0032] Dynamic interaction: In the initial stage of fertilization, the network structure of polyacrylamide rapidly traps fertilizer nutrients, preventing their loss through irrigation or rainfall; simultaneously, biochar adsorbs and stores nutrients through ion exchange. As crop roots grow into the rhizosphere, hydrogen ions and organic acids secreted by the roots exchange with nutrients at the adsorption sites, promoting the desorption and release of adsorbed nutrients. When the soil solution concentration decreases, nutrients in the polyacrylamide network are gradually released. This dynamic balance of "adsorption-desorption" achieves on-demand nutrient supply. Studies have shown that fertilizers with 30% biochar added have a significantly reduced 7-day cumulative nitrogen release rate, demonstrating a clear slow-release effect.

[0033] (vi) Five-layer linkage system-level coupling The five linkage mechanisms mentioned above are not isolated, but rather mutually coupled and progressive, forming a complete closed-loop system: The first layer (physical foundation layer): The physical retention mechanism and the slow-release supply mechanism together construct the physical foundation of "water retention-fertilizer retention-microbe retention". The three-dimensional network structure formed after polyacrylamide absorbs water and swells will retain the biochar particles loaded with microorganisms and fertilizer nutrients in the rhizosphere region of the crop, forming a stable "nutrient-microbe enrichment microdomain". This physical framework provides the necessary spatial support and material guarantee for all subsequent biological activities and chemical transformations.

[0034] The second layer (bioactivation layer): Supported by the physical foundation layer, the microbial activation mechanism and disease resistance and growth-promoting mechanism are activated. The composite microbial agent protected by biochar proliferates extensively in the rhizosphere microdomain: *Bacillus mucilaginosus* secretes organic acids, which decompose native soil minerals to release potassium and silicon, and promote the slow dissociation of water-soluble silicates; *Bacillus amyloliquefaciens* secretes lipopeptide antibiotics and chitinases, forming an inhibitory zone around the rhizosphere to suppress soil-borne pathogens. The porous structure of biochar not only provides shelter for microorganisms but also enriches the organic acids and antibiotics produced by microbial metabolism in the rhizosphere through adsorption, prolonging their duration of action.

[0035] The third layer (crop response layer): Based on the biological activation layer, the root regulation mechanism initiates the response. Sodium naphthaleneacetate (NAA) and sodium indoleacetate (ICA) synergistically stimulate rapid root growth in crops, promoting the abundant development of lateral roots and root hairs. Once the root system is well-developed, the organic carbon sources (sugars, amino acids, etc.) secreted become "energy fuel" for rhizosphere microorganisms. These microorganisms utilize these secretions to further multiply, and the auxin-like substances (such as ICA) and siderophores produced by their metabolism, in turn, stimulate root growth, forming a positive feedback loop of "exogenous hormones promoting root growth - root exudates nourishing microorganisms - microorganisms producing endogenous hormones to further promote root growth."

[0036] The fourth layer (system feedback layer): Under the combined effect of the above multi-level linkages, crops receive a continuous and stable supply of nutrients, resulting in a significant increase in yield. After harvest, the soil retains polyacrylamide-modified aggregate structure, stable biochar particles, and a large amount of organic matter decomposed from dead microorganisms. This increases soil organic matter content, improves aggregate structure, and increases the number of beneficial bacteria, providing a more fertile and healthy growing environment for the next crop.

[0037] This system-level closed loop of "physical structure supporting biological activity - biological activity promoting chemical transformation - chemical transformation feeding back to crop growth - crop growth improving the soil environment" achieves the dual goals of increasing yield in the current year and continuously improving the soil.

[0038] III. Detailed Implementation Method of Preparation Example 1

[0039] 1. Raw material preparation Weigh the raw materials according to the following parts by weight: 40 parts sodium silicate, 30 parts polyacrylamide. 8 parts sodium naphthaleneacetate, 7 parts sodium indoleacetate, 20 parts modified biochar, and 5 parts compound microbial inoculant.

[0040] Preparation of modified biochar: Rice husks were pyrolyzed at 500℃ for 3 hours to obtain rice husk biochar. The biochar was soaked in 1 mol / L phosphoric acid solution for 24 hours, washed until neutral, dried, and then pulverized through a 100-mesh sieve to obtain acid-modified biochar.

[0041] Preparation of the compound microbial agent: Both *Bacillus amyloliquefaciens* and *Bacillus mucilaginosus* are commercially available products. Those skilled in the art may also choose other commercially available similar products conforming to the national standard (GB 20287-2006 "Agricultural Microbial Agents") as substitutes, depending on actual needs.

[0042] 2. Preparation steps S1: Mix the composite microbial agent and modified biochar at a mass ratio of 1:4, spray in an appropriate amount of sterile water (controlling the moisture content to about 30%), stir evenly, and dry at a low temperature of 35℃ until the moisture content is reached. A biochar inoculant carrier was prepared.

[0043] S2: Sodium silicate, polyacrylamide, Sodium naphthaleneacetate and sodium indoleacetate were pulverized and passed through an 80-mesh sieve, and then mixed evenly according to the formula ratio to obtain the basic synergistic powder.

[0044] S3: Feed the carrier obtained in step S1 and the powder obtained in step S2 into a disc granulator, spray in 5% starch paste as a binder (the amount used is 8% of the total mass of the materials), granulate and shape, and dry at 50℃ to the desired moisture content. The granular fertilizer enhancer, measuring 2-4 mm, was obtained by sieving. Example 2

[0045] The process is basically the same as in Example 1, except that: the modified biochar is modified with humic acid, that is, rice husk biochar is soaked in a 2% humic acid solution for 24 hours; the mass ratio of microbial agent to modified biochar is 1:8; and the drying temperature is 40℃. Example 3

[0046] The process is basically the same as in Example 1, except that the raw material ratio is adjusted to: 35 parts sodium silicate, 35 parts polyacrylamide, 5 parts sodium naphthaleneacetate, 5 parts sodium indoleacetate, 25 parts modified biochar, and 8 parts compound microbial inoculant. Example 4

[0047] The results are basically the same as in Example 1, except that the biochar raw material is corn stalks and the pyrolysis temperature is 600℃; the binder is polyvinyl alcohol and the amount used is 5% of the total mass of the material. Example 5

[0048] It is basically the same as Example 1, except that the ratio of Bacillus amyloliquefaciens to Bacillus mucilaginosus in the compound microbial agent is adjusted to 2:1.

[0049] IV. Specific Implementation Methods of the Application Method Example 6

[0050] The fertilizer synergist prepared in Example 1 was mixed evenly with potassium sulfate compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15-15-15 at a mass ratio of 5:100. This mixture was then applied as a base fertilizer at a rate of 30 kg / mu (approximately 1.43 kg / mu of synergist). After fertilization, the fertilizer was covered with soil, and conventional field management was carried out. Example 7

[0051] The fertilizer synergist prepared in Example 2 was mixed with urea at a mass ratio of 3:100 and applied as top dressing at a rate of 20 kg / mu. Irrigation was carried out promptly after fertilization. Example 8

[0052] The fertilizer enhancer prepared in Example 3 was mixed with diammonium phosphate at a mass ratio of 8:100 and applied as a base fertilizer at a rate of 25 kg / mu. Example 9

[0053] The fertilizer enhancer prepared in Example 4 was mixed with potassium chloride at a mass ratio of 10:100 and applied together with the base fertilizer at a rate of 15 kg / mu. Example 10

[0054] The fertilizer synergist prepared in Example 5 was mixed with compound fertilizer at a mass ratio of 1:100 and used as top dressing for fruits and vegetables at a dosage of 10 kg / mu.

[0055] V. Example of Effect Verification (I) Comparative Experiment on Peanut Planting Experimental Design: A field experiment was conducted in the main peanut-growing area of ​​Dezhou, Shandong Province. The soil was sandy loam with a pH of 7.2 and an organic matter content of 1.1%. Seven treatment groups were set up, with three replicates per group, arranged in a randomized block design. The treatment settings are as follows: Examples 1-5: Apply 30 kg / mu of the synergist prepared in Examples 1-5 plus compound fertilizer (15-15-15). Comparative Example 1: CN110172001A Example 5 Formulation (40 parts potassium silicate, 30 parts polyacrylamide, ... 8 parts sodium naphthaleneacetate and 7 parts sodium indoleacetate) + 30 kg / mu of compound fertilizer.

[0056] Comparative Example 2: Only modified biochar (20 parts) and compound fertilizer (30 kg / mu) were added; Comparative Example 3: Only compound microbial inoculant (5 parts) + compound fertilizer 30 kg / mu were added; Comparative Example 4: Conventional fertilization (compound fertilizer only, application rate 50 kg / mu). Experimental results: Peanut yield, available nutrients in the soil, and number of microorganisms were measured at harvest. The results are shown in Table 1.

[0057] Results analysis: Synergistic effect verification: Example 1 achieved a yield of 485 kg / mu with a 40% reduction in fertilizer use (30 kg vs 50 kg), representing a 32.9% increase compared to Comparative Example 4. In terms of fertilizer yield increase efficiency, Comparative Example 2 had an efficiency of 1.06 (53 kg yield increase / 50 kg fertilizer), Comparative Example 3 had an efficiency of 1.16, while Comparative Example 1 had an efficiency of 0.74. Example 1, however, achieved a high efficiency of 4.0, which is 3.77 times that of Comparative Example 2, fully demonstrating synergistic effect.

[0058] Component necessity verification: The yields of Comparative Example 2 (without inoculant) and Comparative Example 3 (without biochar) were both lower than those of Example 1, proving that biochar and inoculant must be present simultaneously to achieve the best effect. The yield of Comparative Example 1 was 402 kg, significantly lower than that of Example 1, demonstrating the synergistic effect of the added component.

[0059] Microbial activity verification: Example 1 showed that the number of soil bacteria reached 8.7 × 10⁻⁶. 6 The CFU / g ratio was 2.4 times that of Comparative Example 4, demonstrating that the biochar carrier effectively promoted the colonization and reproduction of the microbial agent.

[0060] (II) Adaptability tests for different crops Experimental design: Application trials were conducted on wheat, corn, cucumber, and apple, with each group consisting of the invention group (synergist from Example 1 + 20% reduction in fertilizer dosage) and a conventional fertilization group (conventional dosage), with three replicates for each group. The results are shown in Table 2.

[0061] The results show that the synergist of the present invention exhibits good adaptability on different crops, and can still achieve an increase in yield of 8.9%-13.0% even with a 20% reduction in fertilizer use.

[0062] (III) Verification of Soil Improvement Effect Experimental design: After the peanut planting experiment, the changes in soil physicochemical properties were measured, and the results are shown in Table 3.

[0063] The results show that the synergist of this invention can significantly increase soil organic matter content, improve aggregate structure, and enhance fertilizer retention capacity, achieving the dual effect of "increased yield in the same year + continuous soil improvement".

[0064] (iv) Adaptability tests for different soil types To verify the applicability and effectiveness of the synergist of this invention on different soil types, a maize planting experiment was conducted in three typical soil types: sandy loam in Dezhou, Shandong (pH 7.2, organic matter 1.1%), clay soil in Lianyungang, Jiangsu (pH 6.8, organic matter 1.5%), and saline-alkali soil in Ningxia (pH 8.5, organic matter 0.8%). The experiment consisted of two treatment groups: the invention group (using the synergist prepared in Example 1 mixed with compound fertilizer at a ratio of 5:100, applied at a rate of 30 kg / mu) and the conventional control group (applied only with compound fertilizer, applied at a rate of 50 kg / mu). Each group was replicated three times in a randomized block design. The maize variety used was Zhengdan 958, and field management was consistent. Yield and soil-related indicators were measured at harvest, and the results are shown in Table 4.

[0065] Table 4. Application effects on different soil types The results showed that the synergist of this invention exhibited significant yield-increasing effects in all three types of soil, with the largest increase (20.5%) observed in saline-alkali soil. It also effectively reduced soil pH (from 8.5 to 8.1), demonstrating its function in improving saline-alkali soil. The yield increase rate in clay soil reached 11.9%, higher than the 9.9% in sandy loam. This is presumably due to the improved permeability of clay by polyacrylamide and the increased porosity by biochar, with the synergistic effect being more pronounced in clay. The number of soil bacteria increased significantly in all three soil types, verifying the promoting effect of biochar carriers on microbial colonization.

[0066] (v) Comparative tests of different modification methods To investigate the effect of biochar modification on the efficacy of synergists, unmodified biochar, phosphoric acid-modified biochar, and humic acid-modified biochar were prepared, and three synergists were prepared according to the formulation of Example 1 (other components were the same). A peanut planting experiment was conducted on sandy loam soil in Dezhou, Shandong Province, with a fertilizer application rate of 30 kg / mu (synergist + compound fertilizer 5:100), and a control group receiving only 50 kg / mu of compound fertilizer. Each group was replicated three times, and yield, soil bacterial count, and available silicon content were measured. The results are shown in Table 5.

[0067] Table 5 Comparison of the effects of different modification methods The results showed that both modification methods were significantly superior to unmodified biochar. Phosphoric acid modification showed the best yield increase (32.9%) and the highest available silicon content in the soil (145.2 mg / kg), indicating that phosphoric acid modification increased the oxygen-containing functional groups on the biochar surface, enhancing its adsorption and activation capacity for silicates. Simultaneously, the slightly acidic environment created by acid modification promoted the metabolic activity of Bacillus subtilis. Humic acid modification resulted in the highest number of soil bacteria (8.9 × 10⁻⁶). 6 The CFU / g ratio indicates that humic acid, as organic matter, can provide an additional carbon source for microorganisms, which is more conducive to the colonization of microorganisms. Both have their advantages and can be used as preferred embodiments of the present invention.

[0068] (vi) Optimization test of microbial agent ratio The compound microbial agent used in this invention consists of Bacillus amyloliquefaciens and Bacillus mucilaginosus. To explore the optimal ratio of the two bacteria, five treatments were set up with Bacillus amyloliquefaciens:Bacillus mucilaginosus mass ratios (based on the number of effective viable bacteria) of 3:1, 1:1, 1:3, 1:0 (Bacillus amyloliquefaciens only), and 0:1 (Bacillus mucilaginosus only). Other components and preparation methods were the same as in Example 1. A peanut planting experiment was conducted on sandy loam soil in Dezhou, Shandong Province. The fertilizer application rate was 30 kg / mu (synergist + compound fertilizer 5:100), with a control of 50 kg / mu of compound fertilizer only. The yield, disease index (reflecting disease resistance), and available silicon content in the soil were measured, and the results are shown in Table 6.

[0069] Table 6 Comparison of the effects of different microbial agent ratios The results showed that the compound microbial agent was more effective than the single microbial agent. The highest yield (485 kg) was achieved when the two microorganisms were mixed in a 1:1 ratio, and the overall performance was optimal: the disease index (15.3) was lower than the treatment using only *Bacillus mucilaginosus* (28.5), and the available silicon content in the soil (145.6 mg / kg) was higher than the treatment using only *Bacillus amyloliquefaciens* (118.3 mg / kg). A higher proportion of *Bacillus amyloliquefaciens* resulted in superior disease resistance (disease index only 12.5 at a 3:1 ratio), but slightly weaker silicon-releasing ability; a higher proportion of *Bacillus mucilaginosus* resulted in strong silicon-releasing ability (available silicon reaching 151.8 mg / kg at a 1:3 ratio), but decreased disease resistance. The 1:1 ratio achieved a balance between disease resistance and silicon-releasing function, resulting in the best synergistic effect. Therefore, this invention preferably uses an equal mixture of the two microorganisms, but synergistic effects can be achieved within the range of 1:3 to 3:1.

[0070] The raw materials used in this invention are all commercially available industrial products, widely sourced and with controllable costs. Modified biochar can be obtained from the pyrolysis of agricultural waste (rice husks, straw, sawdust, etc.), which reduces production costs and realizes the resource utilization of agricultural waste. In the preparation process, the microbial agent loading uses low-temperature drying, requiring minimal equipment and maintaining good microbial activity; the crushing, mixing, and granulation processes are fully compatible with existing compound fertilizer production lines, requiring no large-scale equipment modifications and facilitating industrial-scale production.

[0071] This invention, by introducing modified biochar and compound microbial agents into the existing quaternary compound system, constructs a five-level dynamic linkage mechanism, achieving system-level synergy of "physical fertilizer retention - biological activation - chemical growth promotion". Field trials have demonstrated that this invention can still achieve significant yield increases while reducing fertilizer use by 40%, with fertilizer yield-increasing efficiency more than three times. It also has multiple benefits, including soil improvement, disease suppression, and enhanced agricultural product quality, demonstrating outstanding ingenuity, complete feasibility, and broad application prospects.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fertilizer enhancement additive, characterized in that: It consists of the following raw materials in parts by weight: 30-50 parts of water-soluble silicate 20-40 parts of polyacrylamide Sodium naphthaleneacetate 2-15 parts Sodium indoleacetate 2-10 parts 10-30 parts of modified biochar 1 to 10 parts of compound microbial inoculant.

2. The fertilizer enhancement additive according to claim 1, characterized in that: The modified biochar is acid-modified or humic acid-modified biochar, which is obtained by pyrolysis of agricultural waste at 400-600°C.

3. The fertilizer enhancement additive according to claim 1, characterized in that: The acid is one or more of phosphoric acid, sulfuric acid, or hydrochloric acid. The modification method is to soak the biochar in an acid solution of 0.5-2 mol / L for 12-24 hours, and then wash and dry it.

4. The fertilizer enhancement additive according to claim 1, characterized in that: The compound microbial agent contains Bacillus amyloliquefaciens and Bacillus mucilaginosus, with an effective viable count of... .

5. The fertilizer enhancement additive according to claim 1, characterized in that: The water-soluble silicate is sodium silicate and / or potassium silicate.

6. A method for preparing a fertilizer synergist additive, characterized in that: Includes the following steps: S1: The composite microbial agent is loaded onto modified biochar and dried at low temperature to obtain the biochar agent carrier; S2: Water-soluble silicates, polyacrylamide, Sodium naphthaleneacetate and sodium indoleacetate are pulverized separately, mixed evenly, and the basic synergistic powder is obtained. S3: Mix the carrier obtained in step S1 with the powder obtained in step S2, add a binder to granulate, dry and sieve to obtain granular fertilizer enhancer.

7. The method for preparing a fertilizer synergist according to claim 6, characterized in that: In step S1, the mass ratio of microbial agent to modified biochar is 1:(5-10), and the drying temperature is 30-40℃.

8. The method for preparing a fertilizer synergist according to claim 6, characterized in that: In step S3, the binder is starch paste, polyvinyl alcohol, or water, and the amount used is 5% to 10% of the total mass of the material.

9. The application of a fertilizer synergist additive, characterized in that: The fertilizer enhancer is mixed with the fertilizer at a mass ratio of (1-10):100 and then applied.

10. The application of the fertilizer synergist additive according to claim 9, characterized in that, The fertilizer is nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer or compound fertilizer.

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