A fermented fly ash-based fertilizer and a method of preparing the same

Abstract

The application discloses a kind of fermented fly ash-based fertilizer and preparation method thereof, it is related to agricultural fertilizer technical field, the present application includes core and the outer layer salt-resistant film coated on the outer surface of core;The core-shell type fermented fly ash-based fertilizer in the application forms the microenvironment of relatively low salt in the seed and seedling rhizosphere of coastal saline-alkali soil rice seedling soil by the synergistic effect of outer layer salt-resistant film and core salt buffer complex;Outer layer salt-resistant film slowly swells under saline-alkali condition, forms low-permeability salt-resistant layer, reduces the migration of external salt ions to rhizosphere;Amorphous silicate-aluminosilicate-organic acid complex in core reduces the effective activity of sodium ions and other salt ions in rhizosphere solution by ion exchange and organic acid slow release.The above-mentioned synergistic effect relieves the stress of salt on seed water absorption and radicle elongation, so that seed can germinate normally and root during seedling raising period, and improve the uniformity of emergence.

Description

Technical Field

[0001] This invention belongs to the field of agricultural fertilizer technology, and in particular relates to a fermented fly ash-based fertilizer and its preparation method. Background Technology

[0002] Rice seedling raising in coastal saline-alkali lands uses local soil as the main raw material to prepare seedling soil. Due to the high background salt content of the soil and the return of salt due to water evaporation, the seeds and seedlings are in a high-salt environment in the rhizosphere for a long time. This leads to difficulties in seed water absorption, slow germination, and hindered root elongation, resulting in low emergence rate and poor seedling uniformity, which directly affects the quality of subsequent machine transplanting. Existing improvement methods include freshwater leaching, incorporation of desulfurized gypsum, and ordinary organic fertilizer. Freshwater leaching can only temporarily reduce the salinity of the topsoil. After water evaporation, the salt will re-accumulate in the topsoil layer with capillary water. Desulfurized gypsum has limited control over the total amount of chloride ions and other salt ions, and cannot form a physical isolation layer in the seed rhizosphere. Ordinary organic fertilizer lacks salt-blocking and salt buffering functions, and it is difficult to form a sustained low-salt microenvironment in the rhizosphere. The seedling raising period is short, and the seedling roots are concentrated in the shallow layer of the seedling tray, making them sensitive to fluctuations in rhizosphere salt concentration. Therefore, we propose a fermented fly ash-based fertilizer and its preparation method. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a fermented fly ash-based fertilizer, comprising a core and an outer salt-barrier membrane covering the outer surface of the core; The core is prepared by drying and granulation of fermentation raw materials comprising the following parts by weight after aerobic and anaerobic fermentation: 35-45 parts fly ash, 15-20 parts chicken manure, 10-15 parts cow manure, 5-10 parts sheep manure, 20-25 parts chopped straw, 0.5-1 part compound microbial agent, and 3-5 parts molasses; The compound microbial agent is composed of Bacillus subtilis, Bacillus mucilaginosus, Saccharomyces cerevisiae and Lactobacillus plantarum in a live count ratio of (2-3):(1-2):(1-2):(3-4); The outer salt barrier membrane is formed by curing a coating solution comprising the following components in parts by weight: 20-30 parts ultrafine fly ash, 3-5 parts sodium alginate, 2-3 parts calcium humate, 1-2 parts glycerol, and water to make up to 100 parts.

[0004] A method for preparing fermented fly ash-based fertilizer includes the following steps: Step S1: Raw material pretreatment: Sieve the fly ash, crush and sieve the chicken manure, cow manure and sheep manure respectively, crush the straw, and prepare compound microbial agent according to the ratio; Step S2: Mixing and blending: Mix fly ash with chopped straw, add chicken manure, cow manure and sheep manure, spray in molasses solution, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and let stand; Step S3: Aerobic fermentation and acid production activation: The mixture is piled up, and the aerobic bacteria portion of the compound microbial agent is introduced. Aerobic fermentation is carried out at 55-65℃ for 5-7 days until the pile temperature drops below 40℃ and does not rise again. Step S4: Anaerobic complexing buffer: Seal the aerobic fermentation product, add the remaining compound bacterial agent and molasses, adjust the moisture content to 65% to 70%, and anaerobic ferment at 30 to 38°C for 12 to 15 days to obtain the complex. Step S5: Low-temperature drying and pulverization: Dry the anaerobic fermentation product at 45-55℃ until the moisture content is ≤20%, pulverize it through a 60-80 mesh sieve to obtain the core material; Step S6: Core granulation: Mix the core material with sodium humate aqueous solution, granulate by disc granulation to obtain spherical particles with a particle size of 2-4 mm, and dry to a moisture content of ≤15% to obtain core particles; Step S7: Coating the outer salt barrier membrane: Prepare a coating solution containing ultrafine fly ash, sodium alginate, and calcium humate. Place the core particles in a fluidized bed coating machine and spray the coating solution into them. Control the coating thickness to be 0.2-0.5 mm and then dry and cure. Step S8: Cooling and Packaging: Cool the core-shell particles to room temperature, and sieve to remove particles with a diameter less than 1 mm and greater than 6 mm to obtain the finished product.

[0005] Further, step S1 includes the following steps: Step S11: Take fly ash with the following requirements: SiO2 content ≥45%, Al2O3 content ≥25%, Fe2O3 content ≤8%, CaO content ≤10%, particle size ≤75μm percentage ≥85%, moisture content ≤5%, and remove coarse particles by passing through a 100-mesh sieve. Step S12: Take chicken manure, cow manure and sheep manure, dry them until the moisture content is ≤30%, remove stones and plastic debris, crush them through a 10-mesh sieve to obtain manure granules with a particle size ≤2mm; Step S13: Take rice straw or corn straw, air dry it until the moisture content is ≤15%, and shred it with a straw cutter until the length is ≤2cm and the length-to-diameter ratio is ≤5:1; Step S14: Weigh out Bacillus subtilis, Bacillus mucilage, Saccharomyces cerevisiae, and Lactobacillus plantarum according to the live bacteria ratio of (2-3):(1-2):(1-2):(3-4), mix them evenly to prepare a compound microbial agent, with a total effective live bacteria count ≥2×10⁻⁴. 8 CFU / g, the viable count of each bacterial species shall not be lower than the corresponding value of the lower limit of the ratio.

[0006] Furthermore, step S2 includes the following steps: Step S21: Put fly ash and chopped straw into a mixer and dry mix at a speed of 20-30 r / min for 5 minutes to make the fly ash evenly adhere to the surface of the chopped straw. Step S22: Add chicken manure, cow manure and sheep manure to the mixer and continue mixing at 20-30 r / min for 10 min, keeping the material temperature at 15-35℃ during the mixing process; Step S23: Dissolve molasses in warm water at 30-40℃, spray it evenly into the mixture, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and then let it stand for 30 minutes. During the standing period, keep the material loose and do not compact it.

[0007] Furthermore, step S3 includes the following steps: Step S31: The obtained mixture is piled into windrows or placed into fermentation tanks, with a pile height of 1.2 to 1.5 m and a pile width of 2 to 3 m. Natural ventilation or intermittent ventilation is used, with a ventilation rate of 0.1 to 0.3 min·m³ of material. Step S32: Take the aerobic bacteria portion of the compound microbial agent, which consists of Bacillus subtilis, Bacillus mucilaginosus, and Saccharomyces cerevisiae. The aerobic bacteria portion accounts for 60% to 70% of the total mass of the compound microbial agent. First, premix the aerobic bacteria portion of the agent with a small amount of material and then sprinkle it into the pile. Step S33: Start timing when the pile temperature naturally rises to 55℃, maintain fermentation at 55-65℃ for 5-7 days, turning the pile every 2 days during this period. When turning the pile, add water according to the dryness of the material to keep the moisture content at 50%-60%. Step S34: When the pile temperature naturally drops below 40℃ and does not rise again for 24 hours, the aerobic fermentation ends. The organic acid content of the obtained product is ≥8%, and the pH is 5.5~6.5.

[0008] Furthermore, step S4 includes the following steps: Step S41: Transfer the aerobic fermentation product from step S3 to a sealed fermentation tank or anaerobic fermentation bag equipped with stirring and temperature control. While filling, compact the material to remove air from the gaps between the materials. The filling coefficient is 0.8 to 0.9. Step S42: Add 1-2 parts of Lactobacillus plantarum from the compound microbial agent to the material after pre-mixing with molasses, adjust the moisture content of the material to 65%-70%, and then seal. Step S43: Control the fermentation temperature to 30-38℃, seal and ferment for 12-15 days, stirring slowly for 5-10 minutes every 3 days at a speed of 10-20 r / min to avoid disrupting the anaerobic environment; Step S44: During the fermentation process, the pH of the material is measured every 24 hours. When the pH stabilizes at 5.0-5.8 and does not decrease significantly for 3 consecutive days, the anaerobic fermentation is terminated. The content of amorphous aluminosilicate-organic acid complex in the obtained product is ≥15%.

[0009] Furthermore, step S5 includes the following steps: Step S51: Dry the anaerobic fermentation product from step S4 with hot air at 45-55℃, with a hot air velocity of 0.5-1.0 m / s and a drying time not exceeding 6 hours, so that the moisture content is reduced to below 20%. Step S52: Crush the dried material with a pulverizer and pass it through a 60-80 mesh sieve. The proportion of material passing through the sieve is ≥90%, and the core material is obtained. The angle of repose of the core material is ≤40°.

[0010] Furthermore, step S6 includes the following steps: Step S61: Take 100 parts of the core base material obtained in step S5, add 5 to 8 parts of a 5% sodium humate aqueous solution, the viscosity of the sodium humate aqueous solution is 200 to 500 mPa·s; Step S62: Add the mixture into the disc granulator, with the disc tilt angle at 45° to 50°, the rotation speed at 25 to 35 r / min, and the granulation time at 15 to 20 min. During the granulation process, spray in 3% to 5% of the total mass of the material with water to obtain spherical particles with a particle size of 2 to 4 mm. Step S63: Dry the wet granules at 50°C until the moisture content is ≤15%, and cool them to room temperature to obtain core granules with a compressive strength ≥20N.

[0011] Furthermore, step S7 includes the following steps: Step S71: Prepare the coating solution by taking 20-30 parts of ultrafine fly ash, 3-5 parts of sodium alginate, 2-3 parts of calcium humate, and 1-2 parts of glycerol, adding water to 100 parts, stirring and dissolving at 60°C, and homogenizing at 20-30 MPa for 30 min to obtain a uniform suspension coating solution with a viscosity of 300-800 mPa·s. Step S72: Place the core particles obtained in step S6 into a fluidized bed coating machine with an inlet air temperature of 50-60℃ and an atomization pressure of 0.2-0.4MPa. Spray in the coating liquid, with the amount of coating liquid being 15%-25% of the mass of the core particles. Control the coating thickness to be 0.2-0.5mm. During the coating process, maintain the material temperature at 35-45℃. Step S73: After the liquid spraying is completed, continue to circulate hot air at 50-60℃ for 10-15 minutes to dry the outer film, so that the moisture content of the outer film after curing is ≤10%.

[0012] Furthermore, step S8 includes the following steps: Step S81: Allow the core-shell particles obtained in step S7 to cool naturally or with cold air to room temperature; Step S82: Pass the cooled particles through a 4-mesh sieve and an 8-mesh sieve in sequence to remove debris with a particle size of less than 1 mm and agglomerated particles with a particle size of more than 6 mm. Step S83: Prepare the core-shell type fermented fly ash base fertilizer. The finished product has a moisture content of ≤12%, a particle size of 2-5mm, an intact outer shell without obvious cracks, and is packaged in a fixed quantity. Store it in a cool and dry place with a temperature of ≤25℃ and a relative humidity of ≤60%.

[0013] The present invention has the following beneficial effects: 1. In this invention, the core-shell fermented fly ash-based fertilizer, through the synergistic effect of the outer salt-barrier membrane and the core salt-buffered complex, creates a relatively low-salt microenvironment in the rhizosphere of seeds and seedlings in coastal saline-alkali rice seedling soil. The outer salt-barrier membrane slowly swells under saline-alkali conditions, forming a low-permeability salt-barrier layer, reducing the migration of external salt ions into the rhizosphere. The amorphous aluminosilicate-organic acid complex in the core reduces the effective activity of sodium ions and other salt ions in the rhizosphere solution through ion exchange and slow release of organic acids. This synergistic effect alleviates the stress of salt on seed water absorption and root elongation, enabling seeds to germinate and take root normally during the seedling stage, and improving seedling uniformity.

[0014] 2. The fermentation process of this invention employs a staged, variable-temperature, variable-oxygen process, first aerobic acid production followed by anaerobic complexation. This allows the active silicon, aluminum, calcium, magnesium, and other components in fly ash to be gradually activated and released by organic acids, forming a complex with salt buffering function with organic acids and microbial metabolites. When this complex is incorporated into the seedling soil, it can buffer changes in rhizosphere pH and salt ion concentration, reducing the impact of salt fluctuations caused by water evaporation, irrigation, or salt return on seedlings, thus providing a more stable growth environment for the seedling roots.

[0015] 3. The core of this invention is granulated from fly ash, chicken manure, cow manure, sheep manure, chopped straw, and a compound microbial agent after thorough fermentation and decomposition. It contains humified organic matter and various beneficial microbial metabolites. The fertilizer granules slowly release nutrients into the seedling soil, improving its granular structure and water and fertilizer retention capacity, and promoting seedling root development. Simultaneously, fly ash, as the main raw material, is utilized as a resource, reducing the pressure of industrial solid waste accumulation and lowering the cost of seedling soil improvement, aligning with the direction of co-utilization of agricultural and industrial solid waste.

[0016] 4. The outer salt-barrier membrane of this invention is composed of materials such as ultrafine fly ash, sodium alginate, and calcium humate. While performing its salt-barrier function, it maintains a certain degree of air permeability to prevent oxygen deficiency in the root zone due to complete sealing. The coating material has good compatibility with the seedling soil environment, does not introduce harmful substances, and does not change the basic tillage properties of the seedling soil. The core-shell structure concentrates the salt-barrier function in the seed rhizosphere region, making it easy to mix directly into the seedling soil. It is suitable for the agronomic operation requirements of rice seedling raising and machine transplanting in coastal saline-alkali areas.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process for preparing a fermented fly ash-based fertilizer according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 As shown, the present invention is a fermented fly ash-based fertilizer, comprising a core and an outer salt-barrier membrane covering the outer surface of the core; The kernel is obtained by drying and granulation after aerobic and anaerobic fermentation of fermentation raw materials containing the following parts by weight: 35-45 parts fly ash, 15-20 parts chicken manure, 10-15 parts cow manure, 5-10 parts sheep manure, 20-25 parts chopped straw, 0.5-1 part compound microbial agent, and 3-5 parts molasses; The compound microbial agent is composed of Bacillus subtilis, Bacillus mucilaginosus, Saccharomyces cerevisiae and Lactobacillus plantarum mixed in a live count ratio of (2-3):(1-2):(1-2):(3-4); The outer salt barrier membrane is formed by curing a coating solution comprising the following components in parts by weight: 20-30 parts ultrafine fly ash, 3-5 parts sodium alginate, 2-3 parts calcium humate, 1-2 parts glycerol, and water to make up to 100 parts.

[0022] A method for preparing fermented fly ash-based fertilizer includes the following steps: Step S1: Raw material pretreatment: Sieve the fly ash, crush and sieve the chicken manure, cow manure and sheep manure respectively, crush the straw, and prepare compound microbial agent according to the ratio; Step S2: Mixing and blending: Mix fly ash with chopped straw, add chicken manure, cow manure and sheep manure, spray in molasses solution, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and let stand; Step S3: Aerobic fermentation and acid production activation: The mixture is piled up, and the aerobic bacteria portion of the compound microbial agent is introduced. Aerobic fermentation is carried out at 55-65℃ for 5-7 days until the pile temperature drops below 40℃ and does not rise again. Step S4: Anaerobic complexing buffer: Seal the aerobic fermentation product, add the remaining compound bacterial agent and molasses, adjust the moisture content to 65% to 70%, and anaerobic ferment at 30 to 38°C for 12 to 15 days to obtain the complex. Step S5: Low-temperature drying and pulverization: Dry the anaerobic fermentation product at 45-55℃ until the moisture content is ≤20%, pulverize it through a 60-80 mesh sieve to obtain the core material; Step S6: Core granulation: Mix the core material with sodium humate aqueous solution, granulate by disc granulation to obtain spherical particles with a particle size of 2-4 mm, and dry to a moisture content of ≤15% to obtain core particles; Step S7: Coating the outer salt barrier membrane: Prepare a coating solution containing ultrafine fly ash, sodium alginate, and calcium humate. Place the core particles in a fluidized bed coating machine and spray the coating solution into them. Control the coating thickness to be 0.2-0.5 mm and then dry and cure. Step S8: Cooling and Packaging: Cool the core-shell particles to room temperature, and sieve to remove particles with a diameter less than 1 mm and greater than 6 mm to obtain the finished product.

[0023] Step S1 includes the following steps: Step S11: Take fly ash with the following requirements: SiO2 content ≥45%, Al2O3 content ≥25%, Fe2O3 content ≤8%, CaO content ≤10%, particle size ≤75μm percentage ≥85%, moisture content ≤5%, and remove coarse particles by passing through a 100-mesh sieve. Step S12: Take chicken manure, cow manure and sheep manure, dry them until the moisture content is ≤30%, remove stones and plastic debris, crush them through a 10-mesh sieve to obtain manure granules with a particle size ≤2mm; Step S13: Take rice straw or corn straw, air dry it until the moisture content is ≤15%, and shred it with a straw cutter until the length is ≤2cm and the length-to-diameter ratio is ≤5:1; Step S14: Weigh out Bacillus subtilis, Bacillus mucilage, Saccharomyces cerevisiae, and Lactobacillus plantarum according to the live bacteria ratio of (2-3):(1-2):(1-2):(3-4), mix them evenly to prepare a compound microbial agent, with a total effective live bacteria count ≥2×10⁻⁴. 8 CFU / g, the viable count of each bacterial species shall not be lower than the corresponding value of the lower limit of the ratio.

[0024] Step S2 includes the following steps: Step S21: Put fly ash and chopped straw into a mixer and dry mix at a speed of 20-30 r / min for 5 minutes to make the fly ash evenly adhere to the surface of the chopped straw. Step S22: Add chicken manure, cow manure and sheep manure to the mixer and continue mixing at 20-30 r / min for 10 min, keeping the material temperature at 15-35℃ during the mixing process; Step S23: Dissolve molasses in warm water at 30-40℃, spray it evenly into the mixture, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and then let it stand for 30 minutes. During the standing period, keep the material loose and do not compact it.

[0025] Step S3 includes the following steps: Step S31: The obtained mixture is piled into windrows or placed into fermentation tanks, with a pile height of 1.2 to 1.5 m and a pile width of 2 to 3 m. Natural ventilation or intermittent ventilation is used, with a ventilation rate of 0.1 to 0.3 min·m³ of material. Step S32: Take the aerobic bacteria portion of the compound microbial agent, which consists of Bacillus subtilis, Bacillus mucilaginosus, and Saccharomyces cerevisiae. The aerobic bacteria portion accounts for 60% to 70% of the total mass of the compound microbial agent. First, premix the aerobic bacteria portion of the agent with a small amount of material and then sprinkle it into the pile. Step S33: Start timing when the pile temperature naturally rises to 55℃, maintain fermentation at 55-65℃ for 5-7 days, turning the pile every 2 days during this period. When turning the pile, add water according to the dryness of the material to keep the moisture content at 50%-60%. Step S34: When the pile temperature naturally drops below 40℃ and does not rise again for 24 hours, the aerobic fermentation ends. The organic acid content of the obtained product is ≥8%, and the pH is 5.5~6.5.

[0026] Step S4 includes the following steps: Step S41: Transfer the aerobic fermentation product from step S3 to a sealed fermentation tank or anaerobic fermentation bag equipped with stirring and temperature control. While filling, compact the material to remove air from the gaps between the materials. The filling coefficient is 0.8 to 0.9. Step S42: Add 1-2 parts of Lactobacillus plantarum from the compound microbial agent to the material after pre-mixing with molasses, adjust the moisture content of the material to 65%-70%, and then seal. Step S43: Control the fermentation temperature to 30-38℃, seal and ferment for 12-15 days, stirring slowly for 5-10 minutes every 3 days at a speed of 10-20 r / min to avoid disrupting the anaerobic environment; Step S44: During the fermentation process, the pH of the material is measured every 24 hours. When the pH stabilizes at 5.0-5.8 and does not decrease significantly for 3 consecutive days, the anaerobic fermentation is terminated. The content of amorphous aluminosilicate-organic acid complex in the obtained product is ≥15%.

[0027] Step S5 includes the following steps: Step S51: Dry the anaerobic fermentation product from step S4 with hot air at 45-55℃, with a hot air velocity of 0.5-1.0 m / s and a drying time not exceeding 6 hours, so that the moisture content is reduced to below 20%. Step S52: Crush the dried material with a pulverizer and pass it through a 60-80 mesh sieve. The proportion of material passing through the sieve is ≥90%, and the core material is obtained. The angle of repose of the core material is ≤40°.

[0028] Step S6 includes the following steps: Step S61: Take 100 parts of the core base material obtained in step S5, add 5 to 8 parts of a 5% sodium humate aqueous solution, the viscosity of the sodium humate aqueous solution is 200 to 500 mPa·s; Step S62: Add the mixture into the disc granulator, with the disc tilt angle at 45° to 50°, the rotation speed at 25 to 35 r / min, and the granulation time at 15 to 20 min. During the granulation process, spray in 3% to 5% of the total mass of the material with water to obtain spherical particles with a particle size of 2 to 4 mm. Step S63: Dry the wet granules at 50°C until the moisture content is ≤15%, and cool them to room temperature to obtain core granules with a compressive strength ≥20N.

[0029] Step S7 includes the following steps: Step S71: Prepare the coating solution by taking 20-30 parts of ultrafine fly ash, 3-5 parts of sodium alginate, 2-3 parts of calcium humate, and 1-2 parts of glycerol, adding water to 100 parts, stirring and dissolving at 60°C, and homogenizing at 20-30 MPa for 30 min to obtain a uniform suspension coating solution with a viscosity of 300-800 mPa·s. Step S72: Place the core particles obtained in step S6 into a fluidized bed coating machine with an inlet air temperature of 50-60℃ and an atomization pressure of 0.2-0.4MPa. Spray in the coating liquid, with the amount of coating liquid being 15%-25% of the mass of the core particles. Control the coating thickness to be 0.2-0.5mm. During the coating process, maintain the material temperature at 35-45℃. Step S73: After the liquid spraying is completed, continue to circulate hot air at 50-60℃ for 10-15 minutes to dry the outer film, so that the moisture content of the outer film after curing is ≤10%.

[0030] Step S8 includes the following steps: Step S81: Allow the core-shell particles obtained in step S7 to cool naturally or with cold air to room temperature; Step S82: Pass the cooled particles through a 4-mesh sieve and an 8-mesh sieve in sequence to remove debris with a particle size of less than 1 mm and agglomerated particles with a particle size of more than 6 mm. Step S83: Prepare the core-shell type fermented fly ash base fertilizer. The finished product has a moisture content of ≤12%, a particle size of 2-5mm, an intact outer shell without obvious cracks, and is packaged in a fixed quantity. Store it in a cool and dry place with a temperature of ≤25℃ and a relative humidity of ≤60%.

[0031] One specific application of this embodiment is: This embodiment was applied to a 667-square-meter coastal saline-alkali land rice seedling raising base. The total salt content of the 0-20cm topsoil layer was 3.2g / kg, and the pH was 8.1. A standard hard disk seedling raising process was used, equipped with an intermittent automatic sprinkler irrigation system. A total of 1200 58cm×28cm seedling hard disks were placed, and the rice variety used was Huai Dao No. 5. The core-shell fermented fly ash-based fertilizer prepared in this embodiment was uniformly mixed into the 0-2cm rhizosphere seedling raising soil layer at an 8% mass ratio. A stable low-salt rhizosphere microenvironment was constructed through the synergistic effect of the outer salt-barrier membrane and the ion buffering effect of the core complex. The specific implementation steps of the fermented fly ash-based fertilizer application in this embodiment are as follows: Raw material ratio The raw materials for kernel fermentation, by weight, are: 40 parts fly ash, 18 parts chicken manure, 12 parts cow manure, 8 parts sheep manure, 22 parts chopped straw, 0.8 parts compound microbial agent, and 4 parts molasses. The compound microbial agent is composed of Bacillus subtilis, Bacillus mucilage, Saccharomyces cerevisiae, and Lactobacillus plantarum in a viable cell ratio of 2.5:1.5:1.5:3.5, with a total effective viable cell count of 2.5 × 10⁻⁶. 8 CFU / g.

[0032] The outer salt barrier coating solution (by weight) consists of 25 parts ultrafine fly ash, 4 parts sodium alginate, 2.5 parts calcium humate, 1.5 parts glycerol, and water to a total of 100 parts.

[0033] Preparation steps Step S1: Raw material pretreatment Step S11: Take fly ash and test its SiO2 content to be 48%, Al2O3 content to be 28%, Fe2O3 content to be 6%, CaO content to be 8%, particle size ≤75μm to be 90%, and moisture content to be 4%; remove coarse particles by passing it through a 100-mesh sieve and set aside.

[0034] Step S12: Take chicken manure, cow manure, and sheep manure, dry them until the moisture content is 28%, remove stones, plastic and other impurities, crush them, and pass them through a 10-mesh sieve to obtain manure granules with a particle size ≤2mm, and set them aside for later use.

[0035] Step S13: Take corn stalks, air dry them until the moisture content is 12%, and shred them with a chaff cutter until the length is ≤1.5cm and the length-to-diameter ratio is ≤4:1 to obtain shredded stalks for later use.

[0036] Step S14: Weigh out Bacillus subtilis, Bacillus mucilaginosus, Saccharomyces cerevisiae, and Lactobacillus plantarum in a live bacteria ratio of 2.5:1.5:1.5:3.5, mix them evenly to prepare a compound microbial agent, and ensure that the live bacteria count of each species is not lower than the corresponding value of the lower limit of the ratio.

[0037] Step S2: Mixing and blending Step S21: Put fly ash and chopped straw into a mixer and dry mix at a speed of 25 r / min for 5 minutes to make the fly ash evenly adhere to the surface of the chopped straw.

[0038] Step S22: Add chicken manure, cow manure, and sheep manure to the mixer and continue mixing at a speed of 25 r / min for 10 min, keeping the material temperature at 25℃ during the mixing process.

[0039] Step S23: Dissolve molasses in 35℃ warm water and spray it evenly into the mixture. Adjust the C / N ratio of the material to 28:1, the moisture content to 58%, and the pH to 7.0. Then let it stand for 30 minutes, keeping the material loose and not compacted during the standing period.

[0040] Step S3: Aerobic fermentation and acid production activation Step S31: Stack the prepared mixture into windrows, with a height of 1.3m and a width of 2.5m. Use intermittent ventilation with a ventilation rate of 0.2 min·m³ of material.

[0041] Step S32: Take the aerobic bacteria portion of the compound microbial agent, which consists of Bacillus subtilis, Bacillus mucilaginosus, and Saccharomyces cerevisiae, accounting for 65% of the total mass of the compound microbial agent; first, premix the aerobic microbial agent with a small amount of material evenly, and then evenly sprinkle it into the pile.

[0042] Step S33: Start timing when the pile temperature naturally rises to 55℃, and maintain fermentation at 55-65℃ for 6 days; turn the pile over every 2 days during this period, and add water as needed depending on the dryness of the material, so that the moisture content is kept at around 55%.

[0043] Step S34: When the pile temperature naturally drops to 38℃ and does not rise again for 24 hours, the aerobic fermentation ends; the organic acid content of the obtained product is 9.2%, and the pH is 6.0.

[0044] Step S4: Anaerobic Complexing Buffer Step S41: Transfer the aerobic fermentation product to a sealed fermentation tank with stirring and temperature control. While filling, compact the material to remove air from the gaps between the materials. The filling coefficient is 0.85.

[0045] Step S42: Add the premixed Lactobacillus plantarum from the compound microbial agent to the material after mixing it with 1.5 parts of molasses, adjust the moisture content of the material to 68%, and then seal the fermentation tank.

[0046] Step S43: Control the fermentation temperature to 35℃ and seal for fermentation for 14 days; during this period, stir slowly for 8 minutes at a speed of 15r / min every 3 days to avoid disrupting the anaerobic environment.

[0047] Step S44: The pH of the material is measured every 24 hours during the fermentation process. Anaerobic fermentation is terminated when the pH stabilizes at 5.4 and does not decrease significantly for 3 consecutive days. The content of amorphous aluminosilicate-organic acid complex in the obtained product is 18.5%.

[0048] Step S5: Low-temperature drying and pulverization Step S51: Dry the anaerobic fermentation product with hot air at 50°C, with a hot air velocity of 0.8 m / s and a drying time of 5 h, so that the moisture content of the material is reduced to 18%.

[0049] Step S52: The dried material is crushed using a pulverizer and passed through a 70-mesh sieve. The proportion of material passing through the sieve is 93%, thus obtaining the core material. The core material has an angle of repose of 38°.

[0050] Step S6: Core Granulation Step S61: Take 100 parts of the core base material and add 6.5 parts of a 5% sodium humate aqueous solution with a viscosity of 350 mPa·s.

[0051] Step S62: Add the mixture into the disc granulator, set the disc tilt angle to 48°, the rotation speed to 30 r / min, and the granulation time to 18 min; spray 4% water of the total mass of the material during the granulation process to obtain spherical particles with a particle size of 2-4 mm.

[0052] Step S63: Dry the wet granules at 50°C until the moisture content is 12%, and cool them to room temperature to obtain the core granules; the compressive strength of the granules is tested to be 26N.

[0053] Step S7: Coating with an outer salt barrier membrane Step S71: Prepare coating solution: Take 25 parts of ultrafine fly ash, 4 parts of sodium alginate, 2.5 parts of calcium humate, and 1.5 parts of glycerol, add water to 100 parts; stir and dissolve at 60℃, then homogenize at 25MPa pressure for 30min to obtain a uniform suspension coating solution with a viscosity of 550mPa·s.

[0054] Step S72: Place the core particles in a fluidized bed coating machine, set the inlet air temperature to 55℃ and the atomization pressure to 0.3MPa, and spray in the above coating liquid; the amount of coating liquid is 20% of the mass of the core particles, control the coating thickness to 0.35mm, and maintain the material temperature at 40℃ during the coating process.

[0055] Step S73: After spraying, continue to circulate hot air at 55℃ for 12 minutes to dry the outer film; after curing, the moisture content of the outer film is 8%.

[0056] Step S8: Cooling and Packaging Step S81: Cool the core-shell particles to room temperature using cold air.

[0057] Step S82: Pass the cooled particles through a 4-mesh sieve and an 8-mesh sieve in sequence to remove debris smaller than 1 mm and agglomerated particles larger than 6 mm.

[0058] Step S83: Prepare the core-shell type fermented fly ash base fertilizer with a moisture content of 10%, a particle size of 2-5 mm, and an intact outer shell without obvious cracks. After quantitative packaging, store it in a cool and dry place at a temperature of 20℃ and a relative humidity of 55%.

[0059] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. 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 the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fermented fly ash-based fertilizer, characterized in that, Includes the core and an outer salt barrier film covering the outer surface of the core; The core is prepared by drying and granulation of fermentation raw materials comprising the following parts by weight after aerobic and anaerobic fermentation: 35-45 parts fly ash, 15-20 parts chicken manure, 10-15 parts cow manure, 5-10 parts sheep manure, 20-25 parts chopped straw, 0.5-1 part compound microbial agent, and 3-5 parts molasses; The compound microbial agent is composed of Bacillus subtilis, Bacillus mucilaginosus, Saccharomyces cerevisiae and Lactobacillus plantarum in a live count ratio of (2-3):(1-2):(1-2):(3-4); The outer salt barrier membrane is formed by curing a coating solution comprising the following components in parts by weight: 20-30 parts ultrafine fly ash, 3-5 parts sodium alginate, 2-3 parts calcium humate, 1-2 parts glycerol, and water to make up to 100 parts.

2. A method for preparing fermented fly ash-based fertilizer, characterized in that, Includes the following steps: Step S1: Raw material pretreatment: Sieve the fly ash, crush and sieve the chicken manure, cow manure and sheep manure respectively, crush the straw, and prepare compound microbial agent according to the ratio; Step S2: Mixing and blending: Mix fly ash with chopped straw, add chicken manure, cow manure and sheep manure, spray in molasses solution, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and let stand; Step S3: Aerobic fermentation and acid production activation: The mixture is piled up, and the aerobic bacteria portion of the compound microbial agent is introduced. Aerobic fermentation is carried out at 55-65℃ for 5-7 days until the pile temperature drops below 40℃ and does not rise again. Step S4: Anaerobic complexing buffer: Seal the aerobic fermentation product, add the remaining compound bacterial agent and molasses, adjust the moisture content to 65% to 70%, and anaerobic ferment at 30 to 38°C for 12 to 15 days to obtain the complex. Step S5: Low-temperature drying and pulverization: Dry the anaerobic fermentation product at 45-55℃ until the moisture content is ≤20%, pulverize it through a 60-80 mesh sieve to obtain the core material; Step S6: Core granulation: Mix the core material with sodium humate aqueous solution, granulate by disc granulation to obtain spherical particles with a particle size of 2-4 mm, and dry to a moisture content of ≤15% to obtain core particles; Step S7: Coating the outer salt barrier membrane: Prepare a coating solution containing ultrafine fly ash, sodium alginate, and calcium humate. Place the core particles in a fluidized bed coating machine and spray the coating solution into them. Control the coating thickness to be 0.2-0.5 mm and then dry and cure. Step S8: Cooling and Packaging: Cool the core-shell particles to room temperature, and sieve to remove particles with a diameter less than 1 mm and greater than 6 mm to obtain the finished product.

3. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Take fly ash with the following requirements: SiO2 content ≥45%, Al2O3 content ≥25%, Fe2O3 content ≤8%, CaO content ≤10%, particle size ≤75μm percentage ≥85%, moisture content ≤5%, and remove coarse particles by passing through a 100-mesh sieve. Step S12: Take chicken manure, cow manure and sheep manure, dry them until the moisture content is ≤30%, remove stones and plastic debris, crush them through a 10-mesh sieve to obtain manure granules with a particle size ≤2mm; Step S13: Take rice straw or corn straw, air dry it until the moisture content is ≤15%, and shred it with a straw cutter until the length is ≤2cm and the length-to-diameter ratio is ≤5:1; Step S14: Weigh out Bacillus subtilis, Bacillus mucilage, Saccharomyces cerevisiae, and Lactobacillus plantarum according to the live bacteria ratio of (2-3):(1-2):(1-2):(3-4), mix them evenly to prepare a compound microbial agent, with a total effective live bacteria count ≥2×10⁻⁴. 8 CFU / g, the viable count of each bacterial species shall not be lower than the corresponding value of the lower limit of the ratio.

4. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Put fly ash and chopped straw into a mixer and dry mix at a speed of 20-30 r / min for 5 minutes to make the fly ash evenly adhere to the surface of the chopped straw. Step S22: Add chicken manure, cow manure and sheep manure to the mixer and continue mixing at 20-30 r / min for 10 min, keeping the material temperature at 15-35℃ during the mixing process; Step S23: Dissolve molasses in warm water at 30-40℃, spray it evenly into the mixture, adjust the C / N ratio of the material to 25-30:1, the moisture content to 55%-60%, and the pH to 6.5-7.5, and then let it stand for 30 minutes. During the standing period, keep the material loose and do not compact it.

5. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: The obtained mixture is piled into windrows or placed into fermentation tanks, with a pile height of 1.2 to 1.5 m and a pile width of 2 to 3 m. Natural ventilation or intermittent ventilation is used, with a ventilation rate of 0.1 to 0.3 min·m³ of material. Step S32: Take the aerobic bacteria portion of the compound microbial agent, which consists of Bacillus subtilis, Bacillus mucilaginosus, and Saccharomyces cerevisiae. The aerobic bacteria portion accounts for 60% to 70% of the total mass of the compound microbial agent. First, premix the aerobic bacteria portion of the agent with a small amount of material and then sprinkle it into the pile. Step S33: Start timing when the pile temperature naturally rises to 55℃, maintain fermentation at 55-65℃ for 5-7 days, turning the pile every 2 days during this period. When turning the pile, add water according to the dryness of the material to keep the moisture content at 50%-60%. Step S34: When the pile temperature naturally drops below 40℃ and does not rise again for 24 hours, the aerobic fermentation ends. The organic acid content of the obtained product is ≥8%, and the pH is 5.5~6.

5.

6. The method for preparing a fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S4 includes the following steps: Step S41: Transfer the aerobic fermentation product from step S3 to a sealed fermentation tank or anaerobic fermentation bag equipped with stirring and temperature control. While filling, compact the material to remove air from the gaps between the materials. The filling coefficient is 0.8 to 0.

9. Step S42: Add 1-2 parts of Lactobacillus plantarum from the compound microbial agent to the material after pre-mixing with molasses, adjust the moisture content of the material to 65%-70%, and then seal. Step S43: Control the fermentation temperature to 30-38℃, seal and ferment for 12-15 days, stirring slowly for 5-10 minutes every 3 days at a speed of 10-20 r / min; Step S44: During the fermentation process, the pH of the material is measured every 24 hours. When the pH stabilizes at 5.0-5.8 and does not decrease significantly for 3 consecutive days, the anaerobic fermentation is terminated. The content of amorphous aluminosilicate-organic acid complex in the obtained product is ≥15%.

7. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S5 includes the following steps: Step S51: Dry the anaerobic fermentation product from step S4 with hot air at 45-55℃, with a hot air velocity of 0.5-1.0 m / s and a drying time not exceeding 6 hours, so that the moisture content is reduced to below 20%. Step S52: Crush the dried material with a pulverizer and pass it through a 60-80 mesh sieve. The proportion of material passing through the sieve is ≥90%, and the core material is obtained. The angle of repose of the core material is ≤40°.

8. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S6 includes the following steps: Step S61: Take 100 parts of the core base material obtained in step S5, add 5 to 8 parts of a 5% sodium humate aqueous solution, the viscosity of the sodium humate aqueous solution is 200 to 500 mPa·s; Step S62: Add the mixture into the disc granulator, with the disc tilt angle at 45° to 50°, the rotation speed at 25 to 35 r / min, and the granulation time at 15 to 20 min. During the granulation process, spray in 3% to 5% of the total mass of the material with water to obtain spherical particles with a particle size of 2 to 4 mm. Step S63: Dry the wet granules at 50°C until the moisture content is ≤15%, and cool them to room temperature to obtain core granules with a compressive strength ≥20N.

9. The method for preparing a fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S7 includes the following steps: Step S71: Prepare the coating solution by taking 20-30 parts of ultrafine fly ash, 3-5 parts of sodium alginate, 2-3 parts of calcium humate, and 1-2 parts of glycerol, adding water to 100 parts, stirring and dissolving at 60°C, and homogenizing at 20-30 MPa for 30 min to obtain a uniform suspension coating solution with a viscosity of 300-800 mPa·s. Step S72: Place the core particles obtained in step S6 into a fluidized bed coating machine with an inlet air temperature of 50-60℃ and an atomization pressure of 0.2-0.4MPa. Spray in the coating liquid, with the amount of coating liquid being 15%-25% of the mass of the core particles. Control the coating thickness to be 0.2-0.5mm. During the coating process, maintain the material temperature at 35-45℃. Step S73: After the liquid spraying is completed, continue to circulate hot air at 50-60℃ for 10-15 minutes to dry the outer film, so that the moisture content of the outer film after curing is ≤10%.

10. The method for preparing fermented fly ash-based fertilizer according to claim 1, characterized in that, Step S8 includes the following steps: Step S81: Allow the core-shell particles obtained in step S7 to cool naturally or with cold air to room temperature; Step S82: Pass the cooled particles through a 4-mesh sieve and an 8-mesh sieve in sequence to remove debris with a particle size of less than 1 mm and agglomerated particles with a particle size of more than 6 mm. Step S83: Prepare the core-shell type fermented fly ash base fertilizer. The finished product has a moisture content of ≤12%, a particle size of 2-5mm, an intact outer shell without obvious cracks, and is packaged in a fixed quantity. Store it in a cool and dry place with a temperature of ≤25℃ and a relative humidity of ≤60%.

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