Plant-derived bio-growth-promoting fertilizer and preparation method thereof

Abstract

The application discloses a plant-source bio-growth-promoting synergistic fertilizer and a preparation method thereof. The fertilizer is prepared by compounding plant-source composite growth-promoting substances, a composite microbial flora and a carrier material in a specific mass ratio. The plant-source composite growth-promoting substances are prepared by solid-state fermentation and extraction of gynostemma pentaphyllum, astragalus and acanthopanax. The composite microbial flora contains brazilian nitrogen-fixing spirillum, fluorescent pseudomonas and brevibacillus brevis, and is embedded and fixed by using kappa-carrageenan microcapsules containing biochar nanoparticles. The carrier is lignosulfonate-modified nano-attapulgite. The application also provides a corresponding preparation method. The granular fertilizer is finally prepared through steps of activating the strains by a composite activation solution, embedding by microencapsulation and carrier loading granulation. The fertilizer combines the synergistic effect of plant-source active substances and functional microorganisms, significantly improves the activity of the flora and the field colonization capacity, and can effectively promote plant growth, improve crop yield and quality.

Description

Technical Field

[0001] This application belongs to the field of microbial compound fertilizer technology, specifically relating to a plant-derived biological growth promoter-enhancing fertilizer and its preparation method. Background Technology

[0002] Currently, the long-term excessive application of chemical fertilizers has led to a series of serious problems, including soil compaction, environmental pollution, and declining quality of agricultural products. To achieve sustainable agricultural development, developing efficient and environmentally friendly green fertilizers has become an important direction. Among them, microbial fertilizers, due to their functions such as nitrogen fixation, phosphorus solubilization, and secretion of growth hormones, have shown great potential in improving soil microecology and promoting plant growth.

[0003] For example, Chinese patent application CN1134408A discloses a compound microbial fertilizer. This technology involves independently cultivating and fermenting four strains of bacteria—nitrogen-fixing bacteria, nitrogen-fixing fungi, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria—and then combining them in a certain proportion to form a compound microbial community. This community is then mixed with auxiliary materials such as fly ash, dried chicken manure, and fertile soil in a specific ratio to obtain the compound microbial fertilizer, which is used to enhance nitrogen fixation, phosphorus solubilization, and potassium solubilization capabilities and improve soil structure. Another example is Chinese patent application CN115504837A, which discloses a compound microbial fertilizer. This compound microbial fertilizer combines inorganic fertilizer, organic fertilizer, and bio-fertilizer in a reasonable way to produce an organic fertilizer with excellent physical properties, a moderate carbon-nitrogen ratio, excellent fertilizer efficiency, and the combined effects of microorganisms and inorganic fertilizers. It can improve soil structure, increase soil nutrients, enhance soil biological activity, strengthen crop resistance, increase crop yield, and improve the quality of agricultural products.

[0004] However, existing microbial fertilizers still face many challenges in practical applications. On the one hand, functional microorganisms are easily inactivated in the complex soil environment after fertilizer processing, storage, and application, making it difficult to guarantee their colonization and long-lasting efficacy. On the other hand, the application of microorganisms or plant extracts alone often has limited effects, making it difficult to fully leverage the synergistic effect of biostimulation and microbial activity. Although existing technologies have attempted to combine plant-derived extracts with microbial agents, or to microencapsulate agents to enhance their stress resistance, how to construct a stable and efficient composite system that achieves the organic combination and synergistic release of plant active ingredients and functional microorganisms remains a technical challenge that urgently needs to be solved in this field.

[0005] Therefore, there is an urgent need to develop a new type of bio-growth promoter-enhanced fertilizer that can not only integrate the growth-promoting effects of plant-derived active substances with the soil-improving effects of functional microorganisms, but also ensure the high activity of the microbial community during storage and the long-term release of efficacy after application through innovative carriers and immobilization technology. Summary of the Invention

[0006] This application addresses the aforementioned deficiencies by providing a plant-derived bio-based growth promoter-enhanced fertilizer and its preparation method. This application proposes a bio-based growth promoter-enhanced fertilizer that uses a mixed fermentation extract of medicinal plants as the source of growth-promoting activity, and is formulated with nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and indoleacetic acid-producing rhizosphere growth-promoting bacteria, all immobilized in microcapsules. This application utilizes lignin sulfonate-modified nano-attapulgite clay as a carrier to achieve stable loading, slow release, and synergistic effects of active substances and bacterial communities in the rhizosphere, thereby effectively improving growth indicators, root development, and crop yield in crops such as corn.

[0007] This application provides the following technical solution: a plant-derived bio-growth promoter-enhanced fertilizer, comprising the following components: plant-derived compound growth promoter, compound microbial community, and carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth-promoting bacteria that produce indoleacetic acid (IAA). The mixing mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is A:B:C, where A=1, B=1-3, and C=2-4. The plant-derived compound growth promoter is calculated on a dry weight basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

[0008] Furthermore, the plant-derived compound growth-promoting substance includes Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of a:b:c, where a is 1-3, b is 1-2, and c is 0.5-1.5.

[0009] Furthermore, the composite microbial community consists of *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*, with the viable count of the three bacteria expressed in colony-forming units (CFU). The viable count is expressed in CFU / mL in the bacterial suspension state or in CFU / g in the microencapsulated bacterial agent state. The viable count ratio of *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* is D:E:F, where D=1, E=0.5-1.5, and F=0.8-2.0, and the viable count ratio is the ratio of the total viable count of the three bacteria in the mixed system.

[0010] Furthermore, the composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology, and the wall material used for microencapsulation includes κ-carrageenan and biochar nanoparticles.

[0011] Furthermore, the biochar nanoparticles have a particle size of 100 nm-500 nm and a specific surface area greater than 200 m². 2 / g.

[0012] Further, the carrier material is nano-attapulgite clay modified with lignosulfonate, comprising the following steps: M1: Add nano-attapulgite with an average particle size of 50nm-200nm to deionized water to prepare a dispersion with a solid content of 1wt% to 6wt%, adjust the pH to 8.0 to 10.0, and disperse it by ultrasonication at 200W to 500W for 10min to 30min. M2: Add an aqueous solution of lignin sulfonate to the dispersion, wherein the amount of lignin sulfonate added is 2wt% to 10wt% of the dry weight of attapulgite, and stir and react at 30℃ to 60℃ for 0.5h to 2h to obtain a surface-coated slurry. M3: The coated slurry is subjected to solid-liquid separation and washed once or twice, then dried at 40℃ to 70℃ for 4h to 10h, pulverized and passed through an 80-200 mesh sieve to obtain a nano-attapulgite carrier material modified with lignin sulfonate surface. The lignin sulfonate used in step M2 is sodium lignin sulfonate and / or calcium lignin sulfonate.

[0013] This application also provides a method for preparing the plant-derived bio-growth promoter-enhanced fertilizer as described above, comprising the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the ratio of live bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 70-90℃ and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 2%-4%; S4: Cool the κ-carrageenan solution obtained in step S3 to 40℃-45℃, and then gently mix it with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 50 mL / min-300 mL / min, and a magnetic stirrer is used to gently stir at 100 rpm-300 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and dispersing them by stirring at 100 rpm-300 rpm for 5 min-20 min. Based on the final volume of the curing solution, the potassium chloride concentration is 0.5 mol / L-1.5 mol / L, and the mass-volume percentage concentration of the biochar nanoparticles is 0.1%-1.0%.

[0014] S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at room temperature with stirring at 50 rpm-200 rpm for 3 min-15 min to ensure that the microencapsulated bacterial agent is evenly dispersed in the carrier and that the concentrated plant-derived compound growth promoter solution forms a wettable bond on the carrier surface. Subsequently, the resulting mixture is extruded and granulated to control the particle size to 1.0 mm-4.0 mm. Finally, the particles are dried at 35℃-55℃ for 2 h-8 h to reduce the moisture content of the finished product to 3 wt%-10 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

[0015] Furthermore, the activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 5 g / L-15 g / L tryptone, 1 g / L-8 g / L yeast extract, and 1 g / L-10 g / L sodium chloride, with the pH adjusted to 6.8–7.4, without the addition of an inorganic nitrogen source. The shaking culture temperature was 28℃-32℃, and the shaking speed was 150 rpm-220 rpm. The late logarithmic phase was determined by an OD600 of 0.8-1.2. S22: The bacterial cells collected in step S21 are centrifuged at 3000 rpm to 6000 rpm for 5 min to 10 min at 4℃ to 10℃ to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the cells at a ratio of 5 mL to 20 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells; during resuspending, place the composite activation solution in a sterile container and gently stir or shake at 100 rpm to 250 rpm, adding the bacterial cells in batches while stirring to form a uniform suspension; then incubate at 28℃ to 30℃ for 1 h to 2 h to obtain activated suspensions of each bacterial strain.

[0016] Furthermore, the composite activating solution is an aqueous solution containing the following components: Aqueous solutions of yeast extract with a mass concentration of 0.5 g / L - 2.0 g / L A trehalose aqueous solution with a mass concentration of 1.0 g / L - 3.0 g / L; An aqueous solution of a plant-derived compound growth promoter concentrate with a volume concentration of 50 mL / L to 150 mL / L, wherein the aqueous solution of the plant-derived compound growth promoter concentrate with a volume concentration of 50-150 mL / L is a solution obtained by mixing 50 mL-150 mL of the plant-derived compound growth promoter concentrate with 1 L of deionized water.

[0017] Furthermore, the preparation method of the concentrated solution of plant-derived compound growth promoters includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and the moisture content is adjusted to 50%-60% to obtain plant-derived compound growth-promoting wet substance; P2: A mixed strain of Aspergillus niger spores and Saccharomyces cerevisiae spores at a ratio of m:n is obtained and inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, followed by solid-state fermentation; wherein m=1-3, n=1-2; wherein the inoculation amount is 1wt% to 8wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 28℃ to 34℃, and the fermentation time is 48h to 120h; during the fermentation process, the material is spread to a thickness of 2cm to 8cm, and is turned over every 12h to 24h to facilitate aeration and uniform fermentation, resulting in a solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-volume ratio of (1:5) to (1:10), and perform ultrasonic-assisted extraction for 30 min to 45 min at an ultrasonic power of 150 W to 300 W. P4: The extract obtained in step P3 is filtered through a ceramic filter membrane of 0.15μm to 0.2μm, and then concentrated through an ultrafiltration membrane of 1000Da to 1200Da to obtain the concentrated solution of the plant-derived compound growth promoter.

[0018] The beneficial effects of this application are as follows: 1. In terms of formulation and carrier design, this application synergistically combines a complex growth-promoting substance obtained from plant-derived fermentation extraction with nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and IAA-producing growth-promoting bacteria, using lignin sulfonate-modified nano-attapulgite as the carrier and dispersion carrier. The plant-derived extract provides usable organic carbon sources and growth-promoting active components for microorganisms and crop roots. The complex microbial community continuously performs nitrogen fixation, phosphate solubilization, and growth-promoting metabolism in the rhizosphere. The modified nano-attapulgite, through its high specific surface area and surface functional groups, improves the dispersion uniformity of active substances and bacteria within the particles, and also adsorbs, retains, and gradually releases some effective components. This allows for a more stable maintenance of effective nutrient supply and microbial activity in the rhizosphere after application, resulting in a more lasting growth-promoting effect and better consistency between treatments.

[0019] 2. This application uses κ-carrageenan as the microcapsule wall material and introduces biochar nanoparticles to participate in microencapsulation and immobilization, resulting in gel microspheres that provide better protection and sustained-release for bacteria in soil environments. κ-carrageenan forms a three-dimensional gel network through ionic cross-linking, providing a relatively stable water-containing microenvironment for bacteria and allowing the diffusion of nutrients and metabolites. Biochar nanoparticles, with their porous structure and large specific surface area, can adsorb some organic nutrients and small-molecule active substances, releasing them gradually in the soil. This provides more continuous nutritional support for bacteria inside and outside the microcapsules and reduces the impact of environmental fluctuations on bacterial activity. Combined with a drip-based process using a circulating dispersion of the curing solution, the microspheres have more uniform particle size and structure, which is beneficial for bacterial survival and colonization after sowing and furrow application, thereby enhancing the sustainability and stability of nitrogen fixation, phosphorus solubilization, and IAA production.

[0020] 3. This application uses a compound activating solution to activate the three bacteria, rather than simply resuspending them in plant-derived concentrate or water. The yeast extract in the compound activating solution provides amino acids and growth factors, while trehalose enhances the bacteria's stress resistance and membrane stability. Combined with the substrate and inducing components of the plant-derived growth-promoting substance concentrate, the bacteria are in a state of high metabolic activity and adaptation before mixing. This process of activation, encapsulation, and loading reduces the physiological gap in the bacteria during microencapsulation and increases the speed of functional activation after entering the rhizosphere, thereby enabling the growth-promoting effect to be more quickly converted into advantages in root growth and nutrient absorption.

[0021] 4. This application modifies the surface of nano-attapulgite soil by coating it with lignin sulfonate, transforming it from a simple inert filler into a functional carrier with both dispersion stability and adsorption complexation capabilities. The anionic groups of lignin sulfonate can improve the dispersibility of attapulgite soil in aqueous and granular systems, reducing agglomeration and uneven encapsulation during granulation; at the same time, it has a certain adsorption and slow-release capacity for organic active substances and trace ions, promoting the formation of a stable wetting and binding layer of plant-derived active components on the carrier surface, reducing the probability of rapid loss of effective components in the soil and rapid decay after the instantaneous peak. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0023] Unless otherwise specified, all materials and reagents used in Examples 1-4 and Comparative Examples 1-4 of this application are commercially available. For example, the potassium chloride used in the curing solution was purchased from Aladdin Biotech Co., Ltd. (product number P112134); the anhydrous calcium chloride used in the ion crosslinking curing of Comparative Example 4 was also purchased from the corresponding calcium chloride reagent product line of Aladdin Biotech Co., Ltd.; the κ-carrageenan used in the microcapsule wall material was purchased from Macklin Biotech Co., Ltd. (product number 22048); and the sodium alginate used in the wall material replacement of Comparative Example 4 was purchased from Macklin Biotech Co., Ltd. (product number S817374). In the following examples and comparative examples of this application, the *Aspergillus niger*, *Azospirillumbrasilense*, *Pseudomonas fluorescens*, and *Brevibacillus brevis* were all obtained from the China General Microbiological Culture Collection Center (CGMCC). The *Aspergillus niger* number is CGMCC No. 5343, the *Azospirillumbrasilense* number is CGMCC No. 267161, the *Pseudomonas fluorescens* number is CGMCC No. 7597, the *Brevibacillus brevis* number is CGMCC No. 21880, and the *Saccharomyces cerevisiae* was obtained from the China Industrial Microbiological Culture Collection Center, with accession number CICC 31299.

[0024] Example 1 This embodiment provides a plant-derived bio-growth promoter-enhanced fertilizer, comprising the following components: a plant-derived compound growth promoter, a compound microbial community, and a carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth-promoting bacteria that produce indoleacetic acid (IAA); The mixing mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is 1:1:2, wherein the plant-derived compound growth promoter is calculated on a dry matter basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

[0025] The plant-derived compound growth-promoting substance includes Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of 1:1.5:1.0.

[0026] The composite microbial community in this embodiment consists of *Azospirillum brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*. The viable count of these three bacteria is expressed in colony-forming units (CFU), specifically in CFU / mL in bacterial suspension or in CFU / g in microencapsulated bacterial agent form. The viable count ratio of the three bacteria is *Azospirillum brasiliensis* : *Pseudomonas fluorescens* : *Bacillus brevis* = 1 : 1.0 : 0.8, where the viable count ratio is the ratio of the total viable count of the three bacteria in the mixed system. Specifically, the nitrogen-fixing bacterium is *Azospirillum brasiliensis*, the phosphate-solubilizing bacterium is *Pseudomonas fluorescens*, and the indoleacetic acid (IAA)-producing rhizosphere growth-promoting bacterium is *Bacillus brevis*.

[0027] The composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology, and the wall material of the microcapsules includes κ-carrageenan and biochar nanoparticles.

[0028] The biochar nanoparticles have a particle size of 100 nm and a specific surface area greater than 200 m². 2 / g.

[0029] The carrier material is nano-attapulgite clay modified with sodium lignosulfonate, and the process includes the following steps: M1: Add attapulgite nanoparticles with an average particle size of 160 nm to deionized water to prepare a dispersion with a solid content of 1 wt%, adjust the pH to 8.0, and disperse it by ultrasonication at 200 W for 10 min. M2: Add an aqueous solution of sodium lignosulfonate to the dispersion, wherein the amount of sodium lignosulfonate added is 2 wt% of the dry weight of attapulgite, and stir and react at 30°C for 0.5 h to obtain a surface-coated slurry. M3: The coated slurry is subjected to solid-liquid separation and washed once, then dried at 40°C for 4 hours, pulverized and passed through an 80-mesh sieve to obtain a nano-attapulgite carrier material modified with sodium lignosulfonate.

[0030] This embodiment also provides a method for preparing the plant-derived bio-growth promoter-enhanced fertilizer as described above, characterized by comprising the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the above-mentioned ratio of viable bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 90°C and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 4% (w / v); S4: Cool the κ-carrageenan solution obtained in step S3 to 45°C, and then gently mix it with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 200 mL / min, and a magnetic stirrer is used to gently stir at 200 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and stirring at 180 rpm for 12 min to disperse them. Based on the final volume of the curing solution, the potassium chloride concentration is 1.5 mol / L and the mass-volume percentage concentration of the biochar nanoparticles is 0.6%.

[0031] S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at room temperature and stirred at 50 rpm for 6 minutes to ensure that the microencapsulated bacterial agent is uniformly dispersed in the carrier and that the concentrated plant-derived compound growth promoter solution forms a wettable bond on the carrier surface. Subsequently, the resulting mixture is extruded and granulated to control the particle size to 1.5 mm. Finally, the particles are dried at 45°C for 5 hours to reduce the moisture content of the finished product to 6 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

[0032] The activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution in this embodiment includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 15 g / L tryptone, 4 g / L yeast extract, and 6 g / L sodium chloride, adjusted to pH 7.4, without the addition of an inorganic nitrogen source. The shaking culture temperature was 32℃ and the shaking speed was 200 rpm. The late logarithmic phase was determined by an OD600 of 1.2. S22: Centrifuge the bacterial cells collected in step S21 at 10°C and 6000 rpm for 9 min to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the cells at a ratio of 12 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells. During resuspending, place the composite activation solution in a sterile container and gently stir or shake at 200 rpm, adding the bacterial cells in batches while stirring to form a uniform suspension. Then, incubate at 30°C for 1.5 h to obtain activated suspensions of each bacterial strain.

[0033] The composite activating solution in this embodiment is an aqueous solution containing the following components: A yeast extract aqueous solution with a mass concentration of 2.0 g / L, The aqueous solution of trehalose with a mass concentration of 2.0 g / L and the aqueous solution of plant-derived compound growth promoter concentrate with a volume concentration of 120 mL / L are provided. The aqueous solution of plant-derived compound growth promoter concentrate with a volume concentration of 120 mL / L is obtained by mixing 120 mL of plant-derived compound growth promoter concentrate with 1 L of deionized water.

[0034] The preparation method of the concentrated plant-derived compound growth promoter in this embodiment includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and then the moisture content is adjusted to 55% to obtain a plant-derived compound growth-promoting wet substance. P2: A mixed strain of Aspergillus niger and Saccharomyces cerevisiae with a spore ratio of 2:1 is inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, and then solid-state fermentation is carried out; wherein, the inoculation amount is 4 wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 31℃, and the fermentation time is 72h; during the fermentation process, the material is spread to a thickness of 5cm, and is turned over once every 18h to facilitate aeration and uniform fermentation, thereby obtaining the solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-to-volume ratio of 1:8, and perform ultrasonic-assisted extraction for 38 minutes at an ultrasonic power of 220W. P4: The extract obtained in step P3 is filtered through a 0.18 μm ceramic filter membrane and then concentrated through an 1100 Da ultrafiltration membrane to obtain the concentrated solution of the plant-derived compound growth promoter.

[0035] Example 2 This embodiment provides a plant-derived bio-growth promoter-enhancing fertilizer, comprising the following components: a plant-derived compound growth promoter, a compound microbial community, and a carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth-promoting bacteria that produce indoleacetic acid (IAA). The mixing mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is 1:2:3, wherein the plant-derived compound growth promoter is calculated on a dry matter basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

[0036] The plant-derived compound growth-promoting substance includes Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of 2:1:0.5.

[0037] The composite microbial community in this embodiment consists of *Azospirillum brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*. The viable count of these three bacteria is expressed in colony-forming units (CFU), specifically in CFU / mL in bacterial suspension or in CFU / g in microencapsulated bacterial agent form. The viable count ratio of the three bacteria is *Azospirillum brasiliensis* : *Pseudomonas fluorescens* : *Bacillus brevis* = 1 : 0.5 : 1.4, where the viable count ratio is the ratio of the total viable count of the three bacteria in the mixed system. Specifically, the nitrogen-fixing bacterium is *Azospirillum brasiliensis*, the phosphate-solubilizing bacterium is *Pseudomonas fluorescens*, and the indoleacetic acid (IAA)-producing rhizosphere growth-promoting bacterium is *Bacillus brevis*.

[0038] The composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology, and the wall material of the microcapsules includes κ-carrageenan and biochar nanoparticles.

[0039] The biochar nanoparticles have a particle size of 180 nm and a specific surface area greater than 200 m². 2 / g.

[0040] The carrier material is nano-attapulgite clay modified with calcium lignosulfonate, and the process includes the following steps: M1: Add nano-attapulgite with an average particle size of 50nm to deionized water to prepare a dispersion with a solid content of 3wt%, adjust the pH to 9.0, and disperse it by ultrasonication at 350W for 18min. M2: Add an aqueous solution of calcium lignosulfonate to the dispersion, wherein the amount of calcium lignosulfonate added is 5 wt% of the dry weight of the attapulgite soil, and stir and react at 45°C for 1.0 h to obtain a surface-coated slurry. M3: The coated slurry is subjected to solid-liquid separation and washed twice, then dried at 55°C for 7 hours, pulverized and passed through a 150-mesh sieve to obtain a nano-attapulgite carrier material modified with calcium lignosulfonate surface.

[0041] This embodiment also provides a method for preparing the plant-derived bio-growth promoter-enhanced fertilizer as described above, characterized by comprising the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the above-mentioned ratio of viable bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 80°C and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 3.2% (w / v); S4: Cool the κ-carrageenan solution obtained in step S3 to 43°C, and then gently mix it with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 300 mL / min, and a magnetic stirrer is used to gently stir at 300 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and stirring at 300 rpm for 20 min to disperse them. Based on the final volume of the curing solution, the potassium chloride concentration is 1.2 mol / L and the mass-volume percentage concentration of the biochar nanoparticles is 1.0%.

[0042] S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at 120 rpm for 3 min at room temperature to ensure that the microencapsulated bacterial agent is evenly dispersed in the carrier and that the concentrated plant-derived compound growth promoter is wetted and bonded to the carrier surface. The resulting mixture is then extruded and granulated to control the particle size to 1.0 mm. Finally, the particles are dried at 35°C for 2 h to reduce the moisture content of the finished product to 3 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

[0043] The activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution in this embodiment includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 10 g / L tryptone, 8 g / L yeast extract, and 10 g / L sodium chloride, adjusted to pH 7.2, without the addition of an inorganic nitrogen source. The shaking culture was conducted at a temperature of 30°C and a rotation speed of 220 rpm. The late logarithmic phase was determined by an OD600 of 1.0. S22: The bacterial cells collected in step S21 are centrifuged at 5000 rpm for 10 min at 8°C to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the cells at a ratio of 20 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells. During resuspending, place the composite activation solution in a sterile container and gently stir or shake at 250 rpm, adding the bacterial cells in batches while stirring to form a uniform suspension. Then, incubate at 29°C for 2 hours to obtain activated suspensions of each bacterial strain.

[0044] The composite activating solution in this embodiment is an aqueous solution containing the following components: A 1.2 g / L aqueous solution of yeast extract; The aqueous solution of trehalose with a mass concentration of 3.0 g / L and the aqueous solution of plant-derived compound growth promoter concentrate with a volume concentration of 150 mL / L are provided. The aqueous solution of plant-derived compound growth promoter concentrate with a volume concentration of 150 mL / L is obtained by mixing 150 mL of plant-derived compound growth promoter concentrate with 1 L of deionized water.

[0045] The preparation method of the concentrated plant-derived compound growth promoter in this embodiment includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and then the moisture content is adjusted to 50% to obtain a plant-derived compound growth-promoting wet substance. P2: A mixed strain of Aspergillus niger and Saccharomyces cerevisiae with a spore ratio of 1:1 is inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, and then solid-state fermentation is carried out; wherein, the inoculation amount is 1 wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 28℃, and the fermentation time is 48h; during the fermentation process, the material is spread to a thickness of 2cm, and is turned over once every 12h to facilitate aeration and uniform fermentation, thereby obtaining a solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-to-volume ratio of 1:10, and perform ultrasonic-assisted extraction for 30 minutes at an ultrasonic power of 150W. P4: The extract obtained in step P3 is filtered through a 0.2 μm ceramic filter membrane and then concentrated through a 1200 Da ultrafiltration membrane to obtain the concentrated solution of the plant-derived compound growth promoter.

[0046] Example 3 This embodiment provides a plant-derived bio-growth promoter-enhancing fertilizer, comprising the following components: a plant-derived compound growth promoter, a compound microbial community, and a carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth-promoting bacteria that produce indoleacetic acid (IAA). The mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is 1:3:4, wherein the plant-derived compound growth promoter is calculated on a dry weight basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

[0047] The plant-derived compound growth-promoting substance includes Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of 3:2:1.5.

[0048] The composite microbial community in this embodiment consists of *Azospirillum brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*. The viable count of these three bacteria is expressed in colony-forming units (CFU), specifically in CFU / mL in bacterial suspension or in CFU / g in microencapsulated bacterial agent form. The viable count ratio of the three bacteria is *Azospirillum brasiliensis* : *Pseudomonas fluorescens* : *Bacillus brevis* = 1 : 1.5 : 2.0, where the viable count ratio is the ratio of the total viable count of the three bacteria in the mixed system. Specifically, the nitrogen-fixing bacterium is *Azospirillum brasiliensis*, the phosphate-solubilizing bacterium is *Pseudomonas fluorescens*, and the indoleacetic acid (IAA)-producing rhizosphere growth-promoting bacterium is *Bacillus brevis*.

[0049] The composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology, and the wall material of the microcapsules includes κ-carrageenan and biochar nanoparticles.

[0050] The biochar nanoparticles have a particle size of 360 nm and a specific surface area greater than 200 m². 2 / g.

[0051] The carrier material is nano-attapulgite clay modified with lignin sulfonate, and the process includes the following steps: M1: Add nano-attapulgite with an average particle size of 200 nm to deionized water to prepare a dispersion with a solid content of 6 wt%, adjust the pH to 10.0, and disperse it by ultrasonication at 500W for 30 min. M2: Add an aqueous solution of calcium lignosulfonate to the dispersion, wherein the amount of calcium lignosulfonate added is 10 wt% of the dry weight of the attapulgite soil, and stir and react at 60°C for 2 hours to obtain a surface-coated slurry. M3: The coated slurry is subjected to solid-liquid separation and washed twice, then dried at 70℃ for 10 hours, pulverized and passed through a 200-mesh sieve to obtain a nano-attapulgite carrier material modified with calcium lignosulfonate surface.

[0052] This embodiment also provides a method for preparing the plant-derived bio-growth promoter-enhanced fertilizer as described above, characterized by comprising the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the above-mentioned ratio of viable bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 70°C and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 2% (w / v); S4: After cooling the κ-carrageenan solution obtained in step S3 to 40°C, it is gently mixed with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 50 mL / min, and a magnetic stirrer is used to gently stir at 100 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and stirring at 100 rpm for 5 min to disperse them. Based on the final volume of the curing solution, the concentration of potassium chloride is 0.5 mol / L, and the mass-volume percentage concentration of biochar nanoparticles is 0.1%.

[0053] S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at room temperature and stirred at 200 rpm for 15 min to ensure that the microencapsulated bacterial agent is evenly dispersed in the carrier and that the concentrated plant-derived compound growth promoter solution forms a wettable bond on the carrier surface. Subsequently, the resulting mixture is extruded and granulated to control the particle size to 4.0 mm. Finally, the particles are dried at 55°C for 8 h to reduce the moisture content of the finished product to 10 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

[0054] The activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution in this embodiment includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 5 g / L tryptone, 1 g / L yeast extract, and 1 g / L sodium chloride, adjusted to pH 6.8, without the addition of an inorganic nitrogen source. The shaking culture was conducted at a temperature of 28°C and a rotation speed of 150 rpm. The late logarithmic phase was determined by an OD600 of 0.8. S22: The bacterial cells collected in step S21 are centrifuged at 3000 rpm for 5 min at 4°C to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the bacterial cells at a ratio of 5 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells; during resuspending, place the composite activation solution in a sterile container and gently stir or shake at 100 rpm, while adding the bacterial cells in batches to form a uniform suspension; then incubate at 28°C for 1 h to obtain the activated suspensions of each bacterial strain.

[0055] The composite activating solution in this embodiment is an aqueous solution containing the following components: A 0.5 g / L aqueous solution of yeast extract; The aqueous solution contains 1.0 g / L trehalose and 50 mL / L plant-derived compound growth promoter concentrate. The 50 mL / L plant-derived compound growth promoter concentrate is obtained by mixing 50 mL of plant-derived compound growth promoter concentrate with 1 L of deionized water.

[0056] The preparation method of the concentrated plant-derived compound growth promoter in this embodiment includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and then the moisture content is adjusted to 60% to obtain a plant-derived compound growth-promoting wet substance. P2: A mixed strain of Aspergillus niger and Saccharomyces cerevisiae with a spore ratio of 3:2 is inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, and then solid-state fermentation is carried out; wherein, the inoculation amount is 8 wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 34℃, and the fermentation time is 120h; during the fermentation process, the material is spread to a thickness of 8cm, and is turned over once every 24h to facilitate aeration and uniform fermentation, thereby obtaining the solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-to-volume ratio of 1:5, and perform ultrasonic-assisted extraction for 45 minutes at an ultrasonic power of 300W. P4: The extract obtained in step P3 is filtered through a 0.15 μm ceramic filter membrane and then concentrated through a 1000 Da ultrafiltration membrane to obtain the concentrated solution of the plant-derived compound growth promoter.

[0057] Example 4 This embodiment provides a plant-derived bio-growth promoter-enhancing fertilizer, comprising the following components: a plant-derived compound growth promoter, a compound microbial community, and a carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth-promoting bacteria that produce indoleacetic acid (IAA). The mixing mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is 1:2.5:3.5, wherein the plant-derived compound growth promoter is calculated on a dry weight basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

[0058] The plant-derived compound growth promoters include Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of 2.5:1.2:1.3.

[0059] The composite microbial community in this embodiment consists of *Azospirillum brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*. The viable count of these three bacteria is expressed in colony-forming units (CFU), specifically in CFU / mL in bacterial suspension or in CFU / g in microencapsulated bacterial agent form. The viable count ratio of the three bacteria is *Azospirillum brasiliensis* : *Pseudomonas fluorescens* : *Bacillus brevis* = 1 : 1.2 : 1.6, where the viable count ratio is the ratio of the total viable count of the three bacteria in the mixed system. Specifically, the nitrogen-fixing bacterium is *Azospirillum brasiliensis*, the phosphate-solubilizing bacterium is *Pseudomonas fluorescens*, and the indoleacetic acid (IAA)-producing rhizosphere growth-promoting bacterium is *Bacillus brevis*.

[0060] The composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology, and the wall material of the microcapsules includes κ-carrageenan and biochar nanoparticles.

[0061] The biochar nanoparticles have a particle size of 500 nm and a specific surface area greater than 200 m². 2 / g.

[0062] The carrier material is nano-attapulgite clay modified with sodium lignosulfonate, and the process includes the following steps: M1: Add nano-attapulgite with an average particle size of 80nm to deionized water to prepare a dispersion with a solid content of 5wt%, adjust the pH to 9.6, and disperse it by ultrasonication at 420W for 24min. M2: Add an aqueous solution of sodium lignosulfonate to the dispersion, wherein the amount of sodium lignosulfonate added is 8 wt% of the dry weight of attapulgite, and stir and react at 55°C for 1.6 h to obtain a surface-coated slurry. M3: The coating slurry is subjected to solid-liquid separation and washed once, then dried at 62°C for 8 hours, pulverized and passed through a 120-mesh sieve to obtain a nano-attapulgite carrier material modified with lignin sulfonate surface. The lignin sulfonate used in step M2 is sodium lignin sulfonate and / or calcium lignin sulfonate.

[0063] This embodiment also provides a method for preparing the plant-derived bio-growth promoter-enhanced fertilizer as described above, characterized by comprising the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the above-mentioned ratio of viable bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 75°C and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 2.8% (w / v); S4: Cool the κ-carrageenan solution obtained in step S3 to 42°C, and then gently mix it with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 120 mL / min, and a magnetic stirrer is used to gently stir at 140 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and stirring at 160 rpm for 8 minutes to disperse them. Based on the final volume of the curing solution, the potassium chloride concentration is 0.9 mol / L and the mass-volume percentage concentration of the biochar nanoparticles is 0.3%.

[0064] S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at room temperature and stirred at 180 rpm for 10 min to ensure that the microencapsulated bacterial agent is uniformly dispersed in the carrier and that the concentrated plant-derived compound growth promoter is wetted and bonded to the carrier surface. The resulting mixture is then extruded and granulated to control the particle size to 3.0 mm. Finally, the particles are dried at 50°C for 6 h to reduce the moisture content of the finished product to 8 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

[0065] The activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution in this embodiment includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 12 g / L tryptone, 6 g / L yeast extract, and 4 g / L sodium chloride, adjusted to pH 7.0, without the addition of an inorganic nitrogen source. The shaking culture temperature was 29°C and the shaking speed was 180 rpm. The late logarithmic phase was determined by an OD600 of 0.9. S22: The bacterial cells collected in step S21 are centrifuged at 4000 rpm for 7 min at 6°C to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the bacterial cells at a ratio of 8 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells; during resuspending, place the composite activation solution in a sterile container and gently stir or shake at 160 rpm, while adding the bacterial cells in batches to form a uniform suspension; then incubate at 28.5℃ for 1.2 h to obtain the activated suspensions of each bacterial strain.

[0066] The composite activating solution in this embodiment is an aqueous solution containing the following components: A yeast extract aqueous solution with a mass concentration of 1.6 g / L The aqueous solution contains 2.4 g / L trehalose and 90 mL / L plant-derived compound growth promoter concentrate. The 90 mL / L plant-derived compound growth promoter concentrate is obtained by mixing 90 mL of plant-derived compound growth promoter concentrate with 1 L of deionized water.

[0067] The preparation method of the concentrated plant-derived compound growth promoter in this embodiment includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and the moisture content is adjusted to 58% to obtain a plant-derived compound growth-promoting wet substance. P2: A mixed strain of Aspergillus niger and Saccharomyces cerevisiae with a spore ratio of 2:1 is inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, and then solid-state fermentation is carried out; wherein, the inoculation amount is 6 wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 32℃, and the fermentation time is 96h; during the fermentation process, the material is spread to a thickness of 6cm, and is turned over once every 16h to facilitate aeration and uniform fermentation, thereby obtaining the solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-to-volume ratio of 1:7, and perform ultrasonic-assisted extraction for 40 minutes at an ultrasonic power of 260W. P4: The extract obtained in step P3 is filtered through a 0.17 μm ceramic filter membrane and then concentrated through a 1050 Da ultrafiltration membrane to obtain the concentrated solution of the plant-derived compound growth promoter.

[0068] Comparative Example 1 Except for the following differences, the remaining steps are the same as in Example 1: In step S5, the curing solution was only a 1.2 mol / L KCl aqueous solution; no biochar nanoparticles were added; during the preparation of the curing solution, the stirring rate when adding biochar nanoparticles to the potassium chloride solution remained at 300 rpm, and stirring was maintained for 20 min; in step S5, the flow rate of the circulating dispersion peristaltic pump during the drip curing process remained at 300 mL / min, and the speed of the magnetic stirrer during the circulating dispersion process remained at 300 rpm; the remaining κ-carrageenan conditions, bacterial activation conditions, and granulation and drying conditions in step S6 were consistent with those in Example 2. Comparative Example 1 yielded a microencapsulated bacterial agent and corresponding fertilizer product without biochar nanoparticles.

[0069] Comparative Example 2 Except for the following differences, the remaining steps are the same as in Example 1: In this comparative example, unmodified nano-attapulgite was used as the carrier material, specifically nano-attapulgite that had been dried at 70°C for 10 hours and passed through a 200-mesh sieve. The remaining steps S1-S6 of the fertilizer preparation method were consistent with those in Example 3. Comparative Example 2 yielded a comparative fertilizer product using an unmodified attapulgite carrier.

[0070] Comparative Example 3 Except for the following differences, the remaining steps are the same as in Example 1.

[0071] In this comparative example of fertilizer preparation, the composite activating solution containing yeast extract powder and trehalose was not prepared in step S1. Instead, the concentrated plant-derived compound growth promoter was directly diluted with deionized water at a volume concentration of 150 mL / L to obtain an aqueous solution of the concentrated plant-derived compound growth promoter, which replaced the composite activating solution in step S1 of the preparation method in Example 1 for subsequent preparation steps. In steps S21-S23 of this comparative example, each strain was centrifuged and resuspended at a ratio of 20 mL of the replacement activating solution per 1 g of wet bacterial cells, and then activated at 29°C for 2 h. Subsequently, the mixture was mixed according to the proportion of live bacteria to obtain a mixed activated bacterial solution. The remaining microencapsulation steps (κ-carrageenan solution concentration, dissolution temperature, cooling and mixing temperature, composition of the solidification solution and circulation dispersion conditions), carrier material preparation steps, and S6 mixing, granulation and drying conditions were all consistent with those in Example 1.

[0072] Comparative Example 4 Except for the following differences, the remaining steps are the same as in Example 1.

[0073] In the preparation of fertilizer in this comparative example, in steps S3-S5, the microcapsule wall material was replaced with sodium alginate instead of κ-carrageenan. Specifically, sodium alginate was added to deionized water to prepare a sodium alginate solution with a mass-volume percentage concentration of 2.0% (w / v), and then mixed with the mixed activated bacterial solution obtained in step S2 at 45°C to form a bacterial-gel mixture. Subsequently, the bacterial-gel mixture was dripped into a curing solution for ionic cross-linking and curing. The curing solution was a 0.20 mol / L calcium chloride aqueous solution, and magnetic stirring was maintained at 300 rpm during the dripping and curing process. The remaining conditions, including bacterial activation conditions, whether biochar nanoparticles were added and their concentration, carrier material preparation, and mixing, granulation, and drying conditions in S6, were consistent with those in Example 1.

[0074] To verify the growth-promoting and efficacy-enhancing effects of different embodiments and comparative examples of this application, a pot experiment was conducted to compare and evaluate maize (Zhengdan 958). Except for the control group (CK), which was a blank and received no fertilizer, all other treatment groups received an equal amount of basic NPK compound fertilizer (N–P2O5–K2O=15–15–15) at sowing, and the corresponding fertilizer was applied once during sowing furrow application. All treatment groups were cultivated and managed under the same environment, soil source, and management system, maintaining consistent soil moisture and avoiding disturbance to rhizosphere sampling caused by external rainfall or erosion. Ten independent biological replicates (n=10) were set up for each treatment. Rhizosphere soil samples were collected uniformly 30 days after sowing to determine the available phosphorus content and IAA content in the rhizosphere soil. Plant height, stem diameter, and aboveground fresh weight were uniformly measured uniformly 90 days after sowing (before and after tasseling), and root samples were collected to determine the total root length. After the crop reached physiological maturity, the grain weight per plant was uniformly measured upon harvest. The mean and standard deviation of each indicator were calculated using the same measurement method and the same statistical caliber, thereby achieving comparability evaluation under the same reproductive period and environmental conditions.

[0075] In this application, biological replicates were performed on different treatment groups to determine seven indicators: plant height, stem diameter, aboveground fresh weight, total root length, available phosphorus in rhizosphere soil, IAA content in rhizosphere soil, and grain weight per plant. Plant height was measured using a crop height measuring instrument, specifically the TPDM-G-1 model from Zhejiang Top Cloud Agriculture Technology Co., Ltd. The measurement procedure was performed according to the instrument's instruction manual. The height from the ground surface to the highest growth point of the plant was measured while the plant was upright. One representative plant was selected from each pot for measurement, and the plant height (cm) was recorded. The mean and standard deviation of each treatment group were statistically analyzed.

[0076] Stem diameter was measured using a digital vernier caliper. The instrument used was a digital vernier caliper from Guilin Guanglu Digital Measurement and Control Co., Ltd., model number 101-101 (measuring range 0–150 mm, resolution 0.01 mm). During the measurement, the caliper was measured once in each of two mutually perpendicular directions at a distance of about 2 cm from the ground surface. The average value was taken as the stem diameter of a single plant (mm). The mean and standard deviation of each treatment group were then calculated (n=10).

[0077] The fresh weight of the aboveground parts was measured using an electronic balance. The instrument used was the JJ-B series electronic balance from Changshu Shuangjie Testing Instrument Factory, model JJ2000B. On the day of sampling, the aboveground parts were cut off (after removing soil and obvious moisture) and weighed immediately. The fresh weight of the aboveground parts (g / plant) was recorded, and the mean and standard deviation of each treatment group were calculated (n=10).

[0078] Total root length was measured using a root system scanning analysis system. After the roots were washed with clean water, they were laid flat on a transparent tray for scanning and imaging. The total root length (m / plant) was calculated using root system analysis software. The root system scanning analysis system can be the HD-WinRHIZO plant root scanning system (used for the analysis of root length, surface area and other indicators) from Shandong Hurd Electronic Technology Co., Ltd., a domestic manufacturer. The calibration, scanning and parameter output were completed according to the instructions. The results were statistically analyzed on a per-plant basis, and the mean and standard deviation of each treatment group were calculated (n=10).

[0079] Available phosphorus in rhizosphere soil was determined using the "sodium bicarbonate extraction-molybdenum antimony spectrophotometric method" as specified in the Chinese National Environmental Protection Standard HJ 704-2014: After extraction and color development of the rhizosphere soil according to the standard method, the absorbance was measured at the specified wavelength and converted to obtain the available phosphorus content (mg / kg); the absorbance was measured using a UV-Vis spectrophotometer, such as the UV-6100S UV-Vis spectrophotometer from Shanghai Yuanxi Instrument Co., Ltd. The wavelength was set according to the instrument manual and measured using a 10 mm cuvette. The mean and standard deviation of each treatment group were calculated (n=10).

[0080] The IAA content in rhizosphere soil was determined by ELISA: Rhizosphere soil was extracted according to the kit instructions, centrifuged, and the supernatant was loaded onto the plate for reaction. The absorbance was read by an ELISA reader and the IAA content (ng / g) was calculated using a standard curve. The ELISA reader used was the RT-6100 ELISA reader from Shenzhen Raydu Life Science Co., Ltd., and the kit used was the Soil Additives (IAA) ELISA Kit from Guangzhou Shitai Technology Co., Ltd., catalog number MM-925204O. The operation was carried out according to the wavelength and reaction conditions specified in the instructions. The results were calculated on a single-sample basis, and the mean and standard deviation of the treatment groups were statistically analyzed (n=10).

[0081] The grain weight per plant was determined after harvest: the grains from each plant were threshed, cleaned, and equilibrated at room temperature before being weighed. The weight of the grains per plant (g) was recorded using a Changshu Shuangjie JJ2000B electronic balance. The mean and standard deviation (n=10) were calculated for each treatment group. The results are shown in Tables 1 and 2. In Tables 1 and 2, the value before the "±" sign is the mean value of the indicator, and the value after the "±" sign is the standard deviation (SD).

[0082] Table 1

[0083] Table 2

[0084] As shown in Tables 1 and 2, the experimental results indicate that, compared with the blank no-fertilizer treatment (CK) and the control treatment with only basic fertilizer applied (NPK), the embodiments of this application showed significant improvements in maize growth traits, root development capacity, rhizosphere functional indicators, and grain yield. Moreover, this improvement was not due to a single factor, but rather to the synergistic effect of plant-derived compound growth promoters, microencapsulated compound microbial communities, and surface-modified carriers.

[0085] Firstly, regarding aboveground growth traits, the maize plant height in Examples 1-4 of this application reached 186.3cm-194.6cm, significantly higher than the CK treatment's 146.8cm and the NPK treatment's 160.4cm; the stem diameter increased to 22.7mm-24.0mm, a significant advantage compared to the CK's 17.6mm and the commercially available bio-fertilizer (Fert-V)'s 20.5mm. The aboveground fresh weight further increased to 276.4g / plant–302.7g / plant, indicating that the fertilizer of this application can significantly enhance the plant's nutrient accumulation capacity during the vegetative growth period. In contrast, although Comparative Examples 1 and 2 showed improvements over the commercially available fertilizer, their aboveground fresh weights were only 246.8g / plant and 254.9g / plant, respectively, significantly lower than the examples of this application, indicating that biochar nanoparticles and lignin sulfonate modified carriers played a key role in promoting slow nutrient release and stabilizing the rhizosphere environment.

[0086] Secondly, regarding root development indicators, the total root length of the embodiments in this application reached 44.1 m / plant - 48.4 m / plant, significantly higher than the 26.9 m / plant of the CK treatment and the 36.4 m / plant of commercially available fertilizers. Especially compared to Comparative Example 3, the total root length of the embodiments in this application increased by approximately 2.6 m / plant - 6.9 m / plant, indicating that the plant-derived compound growth-promoting substance, after being activated by the compound activation liquid, can significantly enhance microbial colonization and root stimulation effects. Although Comparative Example 4 still maintained a certain root-promoting effect, its total root length was 42.1 m / plant, lower than that of the embodiments in this application, indicating that the κ-carrageenan-biochar composite wall material has greater advantages in terms of microcapsule structure stability and sustained release of microorganisms.

[0087] Furthermore, regarding rhizosphere functional indicators, the embodiments of this application showed a significant synergistic improvement in both available phosphorus and IAA content in the rhizosphere soil. Specifically, the available phosphorus content in the rhizosphere soil of Examples 1-4 ranged from 30.2 mg / kg to 34.2 mg / kg, significantly higher than the CK treatment's 14.9 mg / kg, the commercially available fertilizer's 22.6 mg / kg, and Comparative Example 2's 26.7 mg / kg. This indicates that the synergistic effect of phosphate-solubilizing bacteria and plant-derived active substances in the microencapsulated slow-release system significantly enhanced phosphorus activation capacity. Simultaneously, the IAA content in the rhizosphere soil increased to 20.7 ng / g-24.8 ng / g, still showing a significant advantage compared to Comparative Example 3 (17.4 ng / g) and Comparative Example 4 (18.3 ng / g), further verifying the promoting effect of PSE activation and microbial community immobilization on IAA production and stable release.

[0088] Finally, regarding yield traits, the grain weight per plant in the embodiments of this application reached 152.1g-167.9g, an increase of approximately 66.3g-76.3g compared to the CK treatment, and an increase of approximately 30.4g-46.2g compared to commercially available fertilizers. Even compared to Comparative Example 4, the embodiments of this application still showed an increase of approximately 8.2g-24.1g, fully demonstrating that this application achieves improved rhizosphere function, increased aboveground biomass, and ultimately higher yield through the structured synergy of multiple technical elements, rather than simple component superposition.

[0089] In summary, this application organically integrates plant-derived compound growth-promoting substances, microencapsulated compound microbial communities activated by compound activation liquid, and lignin sulfonate-modified nano-attapulgite soil carriers, demonstrating significant and stable synergistic effects in improving the rhizosphere microecological environment, enhancing nutrient activation and absorption efficiency, and increasing crop yield.

[0090] The preferred embodiments disclosed above are merely illustrative of this application. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to better understand and utilize this application. This application is limited only by the claims and their full scope and equivalents.

Claims

1. A plant-derived biological growth promoter-enhanced fertilizer, characterized in that, It comprises the following components: plant-derived compound growth promoter, compound microbial community, and carrier material; the plant-derived compound growth promoter is obtained by extraction from a mixed fermentation broth of at least two medicinal plants; the compound microbial community includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and plant rhizosphere growth promoters that produce indoleacetic acid; The mixing mass ratio of the plant-derived compound growth promoter, the microencapsulated bacterial agent, and the carrier material is A:B:C, where A=1, B=1-3, and C=2-4. The plant-derived compound growth promoter is calculated on a dry weight basis, the microencapsulated bacterial agent is calculated on a wet weight basis, and the carrier material is calculated on a dry weight basis.

2. The fertilizer according to claim 1, characterized in that, The plant-derived compound growth-promoting substance includes Gynostemma pentaphyllum, Astragalus membranaceus, and Acanthopanax senticosus in a dry mass ratio of a:b:c, where a is 1-3, b is 1-2, and c is 0.5-1.

5.

3. The plant-derived biological growth promoter-enhanced fertilizer according to claim 1, characterized in that, The composite microbial community consists of *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis*. The viable count of the three is expressed in colony-forming units (CFUs), which is expressed as CFU / mL in the bacterial suspension state or as CFU / g in the microencapsulated bacterial agent state. The viable count ratio of *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* is D:E:F, where D=1, E=0.5-1.5, and F=0.8-2.

0. The viable count ratio is the ratio of the total number of viable bacteria of the three bacteria in the mixed system.

4. The plant-derived biological growth promoter-enhanced fertilizer according to claim 1, characterized in that, The composite microbial community is a microencapsulated bacterial agent immobilized using microencapsulation technology. The wall material used for microencapsulation includes κ-carrageenan and biochar nanoparticles.

5. The plant-derived bio-growth promoter-enhanced fertilizer according to claim 4, characterized in that, The biochar nanoparticles have a particle size of 100 nm-500 nm and a specific surface area greater than 200 m². 2 / g.

6. The plant-derived bio-growth promoter-enhanced fertilizer according to claim 1, characterized in that, The carrier material is nano-attapulgite clay modified with lignin sulfonate, and the process includes the following steps: M1: Add nano-attapulgite with an average particle size of 50nm-200nm to deionized water to prepare a dispersion with a solid content of 1wt% to 6wt%, adjust the pH to 8.0 to 10.0, and disperse it by ultrasonication at 200W to 500W for 10min to 30min. M2: Add an aqueous solution of lignin sulfonate to the dispersion, wherein the amount of lignin sulfonate added is 2wt% to 10wt% of the dry weight of attapulgite, and stir and react at 30℃ to 60℃ for 0.5h to 2h to obtain a surface-coated slurry. M3: The coated slurry is subjected to solid-liquid separation and washed once or twice, then dried at 40℃ to 70℃ for 4h to 10h, pulverized and passed through an 80-200 mesh sieve to obtain a nano-attapulgite carrier material modified with lignin sulfonate surface. The lignin sulfonate used in step M2 is sodium lignin sulfonate and / or calcium lignin sulfonate.

7. A method for preparing a plant-derived bio-growth promoter-enhanced fertilizer as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Prepare a composite activating solution containing an aqueous solution of a concentrated extract of plant-derived compound growth promoters; S2: The *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* were activated separately using a composite activation solution. The activated suspensions of each strain were then mixed according to the ratio of live bacteria to obtain a mixed activated bacterial solution. S3: Add κ-carrageenan powder to deionized water, heat to 70-90℃ and stir until completely dissolved to form a κ-carrageenan solution with a mass-volume concentration of 2%-4%; S4: Cool the κ-carrageenan solution obtained in step S3 to 40℃-45℃, and then gently mix it with the mixed activated bacterial solution obtained in step S2 at this temperature to obtain a bacterial-carrageenan mixture. S5: The bacterial adhesive mixture obtained in step S4 is dripped into the curing liquid. During the dripping curing process, the curing liquid is circulated and dispersed: a peristaltic pump is used to circulate the curing liquid at a flow rate of 50 mL / min-300 mL / min, and a magnetic stirrer is used to gently stir at 100 rpm-300 rpm to keep the biochar nanoparticles suspended and dispersed in the curing liquid, thereby forming gel microspheres encapsulating composite microbial flora and biochar, and obtaining microencapsulated bacterial agent; The curing solution is an aqueous dispersion of potassium chloride and biochar nanoparticles. It is prepared by dissolving potassium chloride in deionized water to obtain a potassium chloride solution, and then adding the biochar nanoparticles to the potassium chloride solution and stirring at 100 rpm-300 rpm for 5 min-20 min to disperse them. Based on the final volume of the solidified solution, the potassium chloride concentration is 0.5 mol / L–1.5 mol / L, and the mass-volume percentage concentration of the biochar nanoparticles is 0.1%–1.0%. S6: The composite activating liquid prepared in step S1, the microencapsulated bacterial agent prepared in step S5, and the carrier material are mixed. The mixing is carried out at room temperature with stirring at 50 rpm-200 rpm for 3 min-15 min to ensure that the microencapsulated bacterial agent is evenly dispersed in the carrier and that the concentrated plant-derived compound growth promoter solution forms a wettable bond on the carrier surface. Subsequently, the resulting mixture is extruded and granulated to control the particle size to 1.0 mm-4.0 mm. Finally, the particles are dried at 35℃-55℃ for 2 h-8 h to reduce the moisture content of the finished product to 3 wt%-10 wt%, thereby obtaining the plant-derived growth promoter synergistic fertilizer.

8. The method for preparing the plant-derived bio-growth promoter-enhanced fertilizer according to claim 7, characterized in that, The activation of *Azotrophus brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus brevis* using a composite activation solution includes the following steps: S21: *Azotobacter brasiliensis*, *Pseudomonas fluorescens*, and *Bacillus pumilus* were inoculated separately into a universal liquid culture medium and cultured with shaking until the late logarithmic phase, and the bacterial cells were collected separately. The universal liquid culture medium was an aqueous solution containing 5 g / L-15 g / L tryptone, 1 g / L-8 g / L yeast extract, and 1 g / L-10 g / L sodium chloride, with the pH adjusted to 6.8–7.4, without the addition of an inorganic nitrogen source. The shaking culture temperature was 28℃-32℃, and the shaking speed was 150 rpm-220 rpm. The late logarithmic phase was determined by an OD600 of 0.8-1.

2. S22: The bacterial cells collected in step S21 are centrifuged at 3000 rpm to 6000 rpm for 5 min to 10 min at 4℃ to 10℃ to obtain wet bacterial cells after removing the supernatant. S23: Subsequently, based on the wet bacterial cells after centrifugation and removal of supernatant, resuspend the cells at a ratio of 5 mL to 20 mL of the aforementioned composite activation solution per 1 g of wet bacterial cells; during resuspending, place the composite activation solution in a sterile container and gently stir or shake at 100 rpm to 250 rpm, adding the bacterial cells in batches while stirring to form a uniform suspension; then incubate at 28℃ to 30℃ for 1 h to 2 h to obtain activated suspensions of each bacterial strain.

9. The method for preparing the plant-derived bio-growth promoter-enhanced fertilizer according to claim 7, characterized in that, The composite activating solution is an aqueous solution containing the following components: Aqueous solutions of yeast extract with a mass concentration of 0.5 g / L - 2.0 g / L A trehalose aqueous solution with a mass concentration of 1.0 g / L - 3.0 g / L; An aqueous solution of a concentrated plant-derived compound growth promoter with a volume concentration of 50 mL / L-150 mL / L.

10. The method for preparing the plant-derived bio-growth promoter-enhanced fertilizer according to claim 9, characterized in that, The preparation method of the concentrated plant-derived compound growth promoter solution includes the following steps: P1: Gynostemma pentaphyllum, Astragalus membranaceus and Acanthopanax senticosus in the mass ratio are mixed in a dry state, pulverized and the moisture content is adjusted to 50%-60% to obtain plant-derived compound growth-promoting wet substance; P2: A mixed strain of Aspergillus niger spores and Saccharomyces cerevisiae spores at a ratio of m:n is obtained and inoculated into the plant-derived compound growth-promoting wet material obtained in step P1, followed by solid-state fermentation; wherein m=1-3, n=1-2; wherein the inoculation amount is 1wt% to 8wt% of the wet weight of the plant-derived compound growth-promoting wet material, the fermentation temperature is 28℃ to 34℃, and the fermentation time is 48h to 120h; during the fermentation process, the material is spread to a thickness of 2cm to 8cm, and is turned over every 12h to 24h to facilitate aeration and uniform fermentation, resulting in a solid-state fermentation product; P3: Mix the solid fermentation product obtained in step P3 with deionized water at a mass-volume ratio of (1:5) to (1:10), and perform ultrasonic-assisted extraction for 30 min to 45 min at an ultrasonic power of 150 W to 300 W. P4: The extract obtained in step P3 is filtered through a ceramic filter membrane of 0.15μm to 0.2μm, and then concentrated through an ultrafiltration membrane of 1000Da to 1200Da to obtain the concentrated solution of the plant-derived compound growth promoter.

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