Slow-release compound microbial ecological fertilizer

Abstract

The application discloses a slow-release compound microbial ecological fertilizer, which adopts a three-layer gradient slow-release coating structure, takes modified biochar loaded with compound functional bacteria as an inner core, is matched with an organic slow-release nutrient middle layer and a degradable environment response film outer layer, and accurately controls the release rhythm of nutrients and bacterial groups; the application can greatly improve the survival rate and colonization capacity of microbial bacteria, realizes long-acting slow release and on-demand supply of nutrients, significantly improves the fertilizer utilization rate, simultaneously improves the soil micro-ecology, has ecological nature and long-acting fertilizer effect, and is suitable for large-scale agricultural planting popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of microbial ecological fertilizer technology, specifically relating to a slow-release compound microbial ecological fertilizer. Background Technology

[0002] Existing compound microbial ecological fertilizers generally suffer from core technical problems such as poor stability of functional microorganisms, easy inactivation, uncontrollable nutrient release rate, and mismatch with the crop's nutrient requirements during growth. Conventional microbial fertilizers often employ simple mixing processes, directly exposing functional microorganisms to the external environment. During storage, transportation, and field application, they are easily affected by temperature, humidity, soil pH, ultraviolet radiation, and competition from native microorganisms, resulting in significant inactivation of microorganisms and a rapid decline in the number of effective viable bacteria. This significantly reduces the microorganisms' nitrogen fixation, phosphorus solubilization, potassium solubilization, and antibacterial and growth-promoting functions. Simultaneously, traditional fertilizers lack a gradient regulation mechanism for nutrient release. Rapid nutrient release in the early stages easily leads to nutrient loss and seedling burn, while insufficient nutrient supply in the later stages fails to match the stage-specific nutrient requirements of crops during the seedling, growth, and fruiting stages, resulting in short-lasting fertilizer effects and low nutrient utilization rates. Existing technologies using single-coating and simple carrier loading methods cannot simultaneously achieve the dual effects of long-term microbial survival and precise slow-release of nutrients. The survival and slow-release properties cannot be synergistically matched, resulting in poor comprehensive fertilizer application effects and failing to meet the large-scale needs of modern agriculture for long-term planting and soil ecological improvement. Summary of the Invention

[0003] The purpose of this invention is to solve the core technical problems of existing compound microbial fertilizers, such as easy inactivation of functional microorganisms, mismatch between nutrient release and crop fertilizer requirements, low fertilizer efficiency, and short duration of effect. The invention provides a slow-release compound microbial ecological fertilizer that achieves long-term survival and colonization of microorganisms and controlled release of nutrients in stages through an innovative three-layer gradient slow-release coating structure. This adapts to the growth needs of crops throughout their entire growth cycle, while simultaneously restoring the soil microecology and improving the comprehensive utilization efficiency of fertilizers.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A slow-release compound microbial ecological fertilizer comprises a three-layer gradient slow-release structure, consisting of a microbial functional core, an organic slow-release middle layer, and an environmentally responsive slow-release outer layer, from the inside out. The microbial functional core is composed of modified porous biochar, compound functional microbial agents, and cell protectants. The organic slow-release middle layer is a humic acid-seaweed polysaccharide composite nutrient slow-release layer. The environmentally responsive slow-release outer layer is a biodegradable polylactic acid-chitosan composite coating layer.

[0006] In a preferred embodiment of the present invention, the raw material components of each layer are as follows, by weight: 40-50 parts of microbial functional core, 30-35 parts of organic slow-release middle layer, and 15-20 parts of environmentally responsive slow-release outer layer.

[0007] In a preferred embodiment of the present invention, the microbial functional core comprises, by weight: 25-30 parts modified porous biochar, 8-12 parts composite functional microbial agent, and 3-5 parts cell protectant; the modified porous biochar is prepared by high-temperature activated straw biochar through acid-base modification and micropore expansion treatment, with a pore size of 20-50 nm and a specific surface area ≥350 m². 2 / g.

[0008] In a preferred embodiment of the present invention, the composite functional microbial agent is composed of Bacillus subtilis, Bacillus megaterium phosphate-solubilizing, Azotobacter azoformis, and Trichoderma harzianum in a viable count ratio of 3:2:2:1, with a total viable count ≥2.0 × 10⁻⁶. 9 CFU / g; the cell protectant is a compound of mannitol, trehalose, and polyvinylpyrrolidone in a mass ratio of 2:1:1.

[0009] In a preferred embodiment of the present invention, the organic slow-release middle layer comprises, by weight: 18-22 parts of mineral humic acid, 8-10 parts of seaweed polysaccharide, and 4-6 parts of amino acid chelated trace elements; wherein the amino acid chelated trace elements are a mixture of glycine-chelated iron, zinc, boron, and molybdenum.

[0010] In a preferred embodiment of the present invention, the environmentally responsive sustained-release outer layer comprises, by weight: 8-10 parts polylactic acid, 5-7 parts chitosan, 1-3 parts glycerol plasticizer, and 0.5-1 parts nano-silica sustained-release regulator.

[0011] A method for preparing a slow-release compound microbial ecological fertilizer includes the following steps: Step S1: Prepare modified porous biochar by activating straw biochar at high temperature, followed by alternating acid and alkali modification, water washing and drying, and micropore expansion treatment for later use. Step S2: Prepare the microbial functional core by mixing modified porous biochar with cell protectant, adsorbing the composite functional microbial agent by low-temperature spraying, and solidifying at low temperature to obtain core particles. Step S3: Prepare organic slow-release intermediate layer slurry by mixing mineral humic acid, seaweed polysaccharide, amino acid chelated trace elements with water, stirring and gelatinizing at a constant temperature to obtain slow-release intermediate layer slurry. Step S4: Layered coating molding. The core particles are placed in a fluidized bed, the middle layer slurry is sprayed and cured, the outer layer coating liquid is sprayed, the particles are dried at low temperature and granulated, and then screened to obtain a slow-release compound microbial ecological fertilizer.

[0012] In a preferred embodiment of the present invention, in step S2, the low-temperature spraying temperature is 25-30°C, the curing temperature is 35-40°C, and the curing time is 2-3 hours. In a preferred embodiment of the present invention, in step S4, the fluidized bed spraying temperature is 30-35℃, the drying temperature does not exceed 45℃, the low temperature process throughout ensures the activity of microbial cells, the nutrient release cycle of the fertilizer is 90-120 days, and the soil colonization survival rate of microbial cells is ≥85%.

[0013] Application of a slow-release compound microbial ecological fertilizer in the planting of food crops and cash crops and the improvement of degraded soil.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Structural innovation, specifically addressing core technical issues. This invention pioneers a three-layer gradient slow-release encapsulation integrated structure, which differs from traditional single-coating and simple mixing structures. The core layer ensures long-term viability of microbial cells, the middle layer ensures a stable supply of organic nutrients, and the outer layer enables controllable slow release in response to environmental conditions. The three-layer structure synergistically solves the core problems of easy cell inactivation and imbalanced nutrient release cycles. The technical solution is highly targeted and adaptable.

[0015] 2. Excellent cell preservation effect: A novel modified porous biochar composite multi-element cell protectant system is employed. The modified biochar possesses an ultra-large specific surface area and a multi-level microporous structure, which can physically adsorb and lock in microbial cells, isolating them from adverse external environmental interference. The mannitol and trehalose compound protectant maintains the stability of the cell membrane, inhibits cell metabolism and death, and significantly improves the survival rate of cells after fertilizer storage and soil colonization. The cell survival rate is more than 40% higher than conventional products, effectively ensuring the continuous functioning of the microorganisms.

[0016] 3. Precise and controllable slow-release of nutrients, adapting to the needs of crops throughout their entire growth cycle. This invention achieves gradient nutrient release through the synergistic regulation of an organic slow-release middle layer and a biodegradable responsive outer layer. In the early stage, the outer layer degrades slowly, preventing rapid nutrient loss and seedling burn; in the middle stage, the middle layer continuously releases organic nutrients, ensuring vigorous crop growth; and in the later stage, core nutrients and microbial communities are continuously released, extending the fertilizer's effectiveness. The overall nutrient release cycle can reach 90-120 days, fully matching the growth needs of grain and cash crops throughout their entire growth cycle, increasing fertilizer utilization by more than 30%.

[0017] 4. Outstanding ecological benefits, combining soil improvement and growth promotion. This invention uses biodegradable polylactic acid and chitosan environmentally friendly coating materials, leaving no residue and causing no pollution, meeting the needs of ecological agriculture development; the composite functional microbial community can effectively activate soil fixed nutrients, inhibit soil-borne diseases, regulate soil microecological structure, and long-term application can improve soil compaction and acidification problems, and enhance soil fertility.

[0018] 5. The preparation process is simple and controllable, suitable for large-scale production. This invention adopts a low-temperature spray adsorption and fluidized bed layered coating process, with low-temperature operation throughout, avoiding high-temperature damage to the bacterial cells. The process is stable, with a high yield, suitable for industrial mass production, and has a wide range of applications. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a slow-release compound microbial ecological fertilizer provided in an embodiment of the present invention.

[0021] Figure 2 Scanning electron microscope (SEM) image of the microporous structure of the modified porous biochar provided in the embodiments of the present invention.

[0022] Figure 3 This invention provides a flowchart of a method for preparing a slow-release compound microbial ecological fertilizer. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] like Figure 1 As shown, this embodiment of the invention provides a slow-release compound microbial ecological fertilizer, comprising a three-layer gradient slow-release structure, from the inside out: a microbial functional core 1, an organic slow-release middle layer 2, and an environmentally responsive slow-release outer layer 3; the microbial functional core 1 is composed of modified porous biochar, compound functional microbial agents, and cell protectants; the organic slow-release middle layer 2 is a humic acid-seaweed polysaccharide composite nutrient slow-release layer; the environmentally responsive slow-release outer layer 3 is a biodegradable polylactic acid-chitosan composite coating layer; the fertilizer achieves long-term survival of microbial cells and phased slow-release of nutrients through the synergistic regulation of the three-layer gradient structure, matching the nutrient requirements of crops throughout their entire growth period.

[0025] By weight, the raw material components of each layer are as follows: 40-50 parts of microbial functional core, 30-35 parts of organic slow-release middle layer, and 15-20 parts of environmentally responsive slow-release outer layer.

[0026] The microbial functional core comprises, by weight, 25-30 parts modified porous biochar, 8-12 parts composite functional microbial inoculant, and 3-5 parts cell protectant; the modified porous biochar is prepared by high-temperature activated straw biochar through acid-base modification and micropore expansion treatment, with a pore size of 20-50 nm and a specific surface area ≥350 m². 2 / g, see reference Figure 2 .

[0027] The compound functional microbial agent is composed of Bacillus subtilis, Bacillus megaterium, Azotobacter, and Trichoderma harzianum in a viable count ratio of 3:2:2:1, with a total viable count ≥2.0×10⁻⁶. 9 CFU / g; the cell protectant is a compound of mannitol, trehalose, and polyvinylpyrrolidone in a mass ratio of 2:1:1.

[0028] The organic slow-release middle layer comprises, by weight: 18-22 parts mineral humic acid, 8-10 parts seaweed polysaccharide, and 4-6 parts amino acid chelated trace elements; the amino acid chelated trace elements are a mixture of glycine-chelated iron, zinc, boron, and molybdenum.

[0029] The environmentally responsive sustained-release outer layer comprises, by weight: 8-10 parts polylactic acid, 5-7 parts chitosan, 1-3 parts glycerol plasticizer, and 0.5-1 parts nano-silica sustained-release modifier.

[0030] This invention features a precise ratio of components in each layer, relying on the microporous adsorption of modified porous biochar to lock in the microbial cells, and constructing a microenvironmental survival system with a cell protectant to reduce the cell inactivation rate from the root. The organic slow-release middle layer achieves stable release of nutrients in the short to medium term, providing continuous energy for microbial reproduction and crop growth in the middle stage. The environmentally responsive biodegradable outer layer can adaptively regulate the release rate according to soil temperature, humidity, and pH, achieving a gradient release effect of controlled release in the early stage, stable release in the middle stage, and slow release in the later stage, perfectly matching the nutrient requirements of crops throughout their entire growth period.

[0031] like Figure 3 As shown in the figure, this invention provides a method for preparing a slow-release compound microbial ecological fertilizer, comprising the following steps: Step S1: Prepare modified porous biochar by activating straw biochar at high temperature, followed by alternating acid and alkali modification, water washing and drying, and micropore expansion treatment for later use. Step S2: Prepare the microbial functional core by mixing modified porous biochar with cell protectant, adsorbing the composite functional microbial agent by low-temperature spraying, and solidifying at low temperature to obtain core particles. Step S3: Prepare organic slow-release intermediate layer slurry by mixing mineral humic acid, seaweed polysaccharide, amino acid chelated trace elements with water, stirring and gelatinizing at a constant temperature to obtain slow-release intermediate layer slurry. Step S4: Layered coating molding. The core particles are placed in a fluidized bed, the middle layer slurry is sprayed and cured, the outer layer coating liquid is sprayed, the particles are dried at low temperature and granulated, and then screened to obtain a slow-release compound microbial ecological fertilizer.

[0032] In step S2, the low-temperature spraying temperature is 25-30℃, the curing temperature is 35-40℃, and the curing time is 2-3 hours. In step S4, the fluidized bed spraying temperature is 30-35℃, and the drying temperature does not exceed 45℃. The entire process uses low-temperature technology to ensure the activity of the microbial cells. The fertilizer's nutrient release cycle is 90-120 days, and the soil colonization survival rate of the microbial cells is ≥85%, which is more than 30% higher than that of conventional microbial fertilizers.

[0033] Application of a slow-release compound microbial ecological fertilizer in the planting of food crops and cash crops and the improvement of degraded soil.

[0034] Example 1 A slow-release compound microbial ecological fertilizer, by weight, comprises the following components in each layer: 45 parts microbial functional core, 32 parts organic slow-release middle layer, and 18 parts environmentally responsive slow-release outer layer.

[0035] Microbial functional core: 28 parts modified porous biochar, 10 parts compound functional microbial inoculant, and 4 parts cell protectant; the compound functional microbial inoculant is a mixture of Bacillus subtilis, Bacillus megaterium, Azotobacter, and Trichoderma harzianum in a viable count ratio of 3:2:2:1, with a total viable count ≥2.0×10⁻⁶. 9 CFU / g; the cell protectant is a mixture of mannitol, trehalose, and polyvinylpyrrolidone in a mass ratio of 2:1:1.

[0036] Organic slow-release middle layer: 20 parts mineral humic acid, 9 parts seaweed polysaccharide, and 5 parts amino acid chelated trace elements.

[0037] Environmentally responsive sustained-release outer layer: 9 parts polylactic acid, 6 parts chitosan, 2 parts glycerol plasticizer, and 0.8 parts nano silica.

[0038] Preparation method: Step S1, Preparation of modified porous biochar: The straw biochar was activated at 550℃ for 2 hours, then alternately soaked in 0.5 mol / L sodium hydroxide solution and 0.3 mol / L hydrochloric acid solution for 2 hours each time. After washing with water until neutral, it was dried at 80℃ and subjected to micropore enlargement treatment using an air jet mill to control the pore size to 20-50 nm and the specific surface area to ≥350 m² / g. 2 / g, for later use.

[0039] Step S2, preparation of microbial functional core: The modified porous biochar and the cell protectant are mixed and stirred evenly, the temperature is controlled at 28℃, and the composite functional microbial agent is uniformly adsorbed into the micropores of the biochar using a low-temperature spraying process. The mixture is then cured at 38℃ for 2.5h to obtain core particles.

[0040] Step S3, Preparation of organic slow-release intermediate layer slurry: Add mineral humic acid, seaweed polysaccharide, amino acid chelated trace elements to deionized water, stir at a constant temperature of 45℃ for 1.5h to gelatinize, and obtain a uniform slow-release slurry.

[0041] Step S4, layered coating molding: The core particles are put into a fluidized bed, the fluidized bed temperature is controlled at 32℃, the middle layer slurry is sprayed at a uniform speed and cured for 30 minutes; then the outer layer coating liquid is sprayed, dried at a low temperature of 40℃, and the 2-4mm particles are sieved to obtain the finished slow-release compound microbial ecological fertilizer.

[0042] Example 2 A slow-release compound microbial ecological fertilizer, by weight, comprises the following components in each layer: 40 parts of microbial functional core, 30 parts of organic slow-release middle layer, and 15 parts of environmentally responsive slow-release outer layer.

[0043] Microbial functional core: 25 parts modified porous biochar, 8 parts composite functional microbial inoculants, and 3 parts cell protectants.

[0044] Organic slow-release middle layer: 18 parts mineral humic acid, 8 parts seaweed polysaccharide, and 4 parts amino acid chelated trace elements.

[0045] Environmentally responsive sustained-release outer layer: 8 parts polylactic acid, 5 parts chitosan, 1 part glycerol plasticizer, and 0.5 parts nano silica.

[0046] The preparation method is the same as in Example 1, with minor adjustments to the process parameters: low-temperature spraying temperature 25℃, curing temperature 35℃, curing time 3h, fluidized bed spraying temperature 30℃, and drying temperature 42℃.

[0047] Example 3 A slow-release compound microbial ecological fertilizer, by weight, comprises the following components for each layer: 50 parts of microbial functional core, 35 parts of organic slow-release middle layer, and 20 parts of environmentally responsive slow-release outer layer.

[0048] Microbial functional core: 30 parts modified porous biochar, 12 parts composite functional microbial inoculant, and 5 parts cell protectant.

[0049] Organic slow-release middle layer: 22 parts mineral humic acid, 10 parts seaweed polysaccharide, and 6 parts amino acid chelated trace elements.

[0050] Environmentally responsive sustained-release outer layer: 10 parts polylactic acid, 7 parts chitosan, 3 parts glycerol plasticizer, and 1 part nano silica.

[0051] The preparation method is the same as in Example 1, with minor adjustments to the process parameters: low-temperature spraying temperature 30℃, curing temperature 40℃, curing time 2h, fluidized bed spraying temperature 35℃, and drying temperature 45℃.

[0052] Comparative Example 1 (Conventional Mixed Microbial Fertilizer) Using traditional processes, equal amounts of compound functional microbial agents, humic acid, and organic fertilizer raw materials are directly mixed and granulated. There is no modified biochar loading or three-layer slow-release coating structure. The remaining raw material components are the same as in Example 1.

[0053] Comparative Example 2 (Single-coated microbial fertilizer) The method uses only a chitosan monolayer coating structure, without modified biochar core loading and organic slow-release middle layer, and the raw material composition is the same as in Example 1, prepared by conventional coating process.

[0054] The performance testing is as follows: To verify the technical effects of this invention, the viable bacteria survival rate, nutrient release cycle, fertilizer utilization rate, and soil colonization effect of the products in each embodiment and comparative example were tested. The test results are as follows: 1. Survival rate of live bacteria after 6 months of storage at room temperature: 89.2% in Example 1, 86.5% in Example 2, and 87.8% in Example 3; 42.3% in Comparative Example 1 and 65.7% in Comparative Example 2. The three-layer structure of this invention can significantly improve the storage stability of bacteria and effectively solve the problem of easy inactivation of bacteria.

[0055] 2. Nutrient slow-release period: The effective nutrient release period in Example 1 is 115 days, in Example 2 it is 98 days, and in Example 3 it is 108 days; in Comparative Example 1, nutrients are released rapidly with an effective period of only 45 days, and in Comparative Example 2 it is 72 days. The slow-release period of this invention is significantly extended, perfectly adapting to the needs of crops throughout their entire growth period.

[0056] 3. Field fertilizer utilization rate: The fertilizer utilization rate of Example 1 was 58.6%, Example 2 was 55.3%, and Example 3 was 57.2%; the comparative example 1 was 26.8% and the comparative example 2 was 41.2%. The fertilizer utilization rate of the present invention has a significant effect.

[0057] 4. Soil microbial colonization survival rate: Example 1 showed 88.5%, while Comparative Example 1 showed only 38.2%, proving that the structure of the present invention can effectively ensure the survival and colonization of microorganisms in the soil and continuously exert ecological functions.

[0058] The experimental results show that the present invention, through the creative design of a three-layer gradient slow-release structure, fundamentally solves the core technical problems of easy inactivation of microbial cells and mismatch between nutrient release and crop fertilizer requirement cycle in the prior art.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A slow-release compound microbial ecological fertilizer, characterized in that, It comprises a three-layer gradient sustained-release structure, consisting of a microbial functional core, an organic sustained-release middle layer, and an environmentally responsive sustained-release outer layer, from the inside out. The microbial functional core is composed of modified porous biochar, composite functional microbial agents, and cell protectants. The organic sustained-release middle layer is a humic acid-seaweed polysaccharide composite nutrient sustained-release layer. The environmentally responsive sustained-release outer layer is a biodegradable polylactic acid-chitosan composite coating layer.

2. The slow-release compound microbial ecological fertilizer according to claim 1, characterized in that, By weight, the raw material components of each layer are as follows: 40-50 parts of microbial functional core, 30-35 parts of organic slow-release middle layer, and 15-20 parts of environmentally responsive slow-release outer layer.

3. The slow-release compound microbial ecological fertilizer according to claim 2, characterized in that, The microbial functional core comprises, by weight, 25-30 parts of modified porous biochar, 8-12 parts of composite functional microbial inoculant, and 3-5 parts of cell protectant; the modified porous biochar is prepared by high-temperature activated straw biochar through acid-base modification and micropore expansion treatment, with a pore size of 20-50 nm and a specific surface area ≥350 m². 2 / g.

4. The slow-release compound microbial ecological fertilizer according to claim 3, characterized in that, The compound functional microbial agent is composed of Bacillus subtilis, Bacillus megaterium, Azotobacter, and Trichoderma harzianum in a viable count ratio of 3:2:2:1, with a total viable count ≥2.0 × 10⁻⁶. 9 CFU / g; the cell protectant is a compound of mannitol, trehalose, and polyvinylpyrrolidone in a mass ratio of 2:1:

1.

5. The slow-release compound microbial ecological fertilizer according to claim 2, characterized in that, The organic slow-release middle layer comprises, by weight: 18-22 parts mineral humic acid, 8-10 parts seaweed polysaccharide, and 4-6 parts amino acid chelated trace elements; the amino acid chelated trace elements are a mixture of glycine-chelated iron, zinc, boron, and molybdenum.

6. The slow-release compound microbial ecological fertilizer according to claim 2, characterized in that, The environmentally responsive sustained-release outer layer comprises, by weight: 8-10 parts polylactic acid, 5-7 parts chitosan, 1-3 parts glycerol plasticizer, and 0.5-1 parts nano-silica sustained-release regulator.

7. A method for preparing a slow-release compound microbial ecological fertilizer according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Prepare modified porous biochar by activating straw biochar at high temperature, followed by alternating acid and alkali modification, water washing and drying, and micropore expansion treatment for later use. Step S2: Prepare the microbial functional core by mixing modified porous biochar with cell protectant, adsorbing the composite functional microbial agent by low-temperature spraying, and solidifying at low temperature to obtain core particles. Step S3: Prepare organic slow-release intermediate layer slurry by mixing mineral humic acid, seaweed polysaccharide, amino acid chelated trace elements with water, stirring and gelatinizing at a constant temperature to obtain slow-release intermediate layer slurry. Step S4: Layered coating molding. The core particles are placed in a fluidized bed, the middle layer slurry is sprayed and cured, the outer layer coating liquid is sprayed, the particles are dried at low temperature and granulated, and then screened to obtain a slow-release compound microbial ecological fertilizer.

8. The method for preparing the slow-release compound microbial ecological fertilizer according to claim 7, characterized in that, In step S2, the low-temperature spraying temperature is 25-30℃, the curing temperature is 35-40℃, and the curing time is 2-3 hours.

9. The method for preparing the slow-release compound microbial ecological fertilizer according to claim 7, characterized in that, In step S4, the fluidized bed spraying temperature is 30-35℃, the drying temperature does not exceed 45℃, and the low-temperature process throughout ensures the activity of microbial cells. The nutrient release cycle of the fertilizer is 90-120 days, and the soil colonization survival rate of microbial cells is ≥85%.

10. The application of a slow-release compound microbial ecological fertilizer according to any one of claims 1-6 in the planting of food crops and cash crops and the improvement of degraded soil.

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