Biomass-based slow-release biofertilizer and preparation method thereof

Abstract

The application relates to the field of biological fertilizers, and particularly discloses a biomass-based slow-release biological fertilizer and a preparation method thereof. The biomass-based slow-release biological fertilizer comprises raw materials: a chemical fertilizer component, a functional fiber matrix, an inorganic cementing material, a composite synergist, a microbial agent and a chelating agent. The inorganic cementing material comprises solid-phase reactants and liquid-phase reactants in a mass ratio of 1-3:1. The solid-phase reactants and the liquid-phase reactants are used as the inorganic cementing material, a low-temperature chemical self-curing system is adopted, a firm crystal network is generated through in-situ reaction of the inorganic cementing material under mild conditions of 15-40 DEG C, the fertilizer particles are endowed with a mechanical strength of 8N or more, and powdering and transportation damage are effectively avoided. Meanwhile, the whole preparation process is low-temperature, and the activity of the microbial agent is ensured from being damaged, and the survival rate of the microbial agent is as high as 89% or more.

Description

Technical Field

[0001] This invention relates to the field of bio-fertilizer technology, specifically to a biomass-based slow-release bio-fertilizer and its preparation method. Background Technology

[0002] Chemical fertilizers are a core production material for ensuring global food security, but traditional fertilizers have low utilization rates (nitrogen fertilizers approximately 30%-50%), and their excessive application has led to a series of serious environmental problems such as soil compaction, acidification, and eutrophication of water bodies. Therefore, developing new fertilizers that combine efficient utilization of fertilizer components with environmental friendliness has become an urgent need for sustainable agricultural development. Slow-release bio-fertilizers, due to their ability to precisely regulate the release of fertilizer components and utilize beneficial microorganisms to synergistically improve soil and promote crop growth, have become a research hotspot in this field.

[0003] Currently, the main technical routes for slow-release fertilizers are divided into physical coating type and matrix slow-release type. Physical coating technology, such as the layered coated fertilizer disclosed in CN120157543B, effectively isolates microorganisms from high-salt environments by coating an inorganic fertilizer core with an organic layer and a microbial layer. However, its process is relatively complex, and the integrity of the coating is crucial to the slow-release effect; it is easily damaged during transportation and application, leading to a "sudden release" of fertilizer components. Furthermore, some coating materials (such as polyolefins) are difficult to degrade, posing a risk of secondary pollution.

[0004] Matrix-based slow-release technology aims to blend fertilizer components with matrix materials and granulate them into a single unit. However, this technology has long faced a core contradiction: it is difficult to simultaneously achieve optimal granule mechanical strength, microbial activity, and processing techniques. On one hand, to protect microbial activity, low-temperature physical bonding processes are typically used, such as granulation at room temperature using bentonite or starch as binders. While this method is gentle on microorganisms, the granules are essentially simple physical accumulations of materials with a loose internal structure and extremely low mechanical strength (typically <5N). They are easily broken and pulverized during packaging, transportation, and application, and rapidly disintegrate upon contact with water, leading to an explosive release of fertilizer components and failing to achieve effective slow release. On the other hand, to obtain high mechanical strength, high-temperature melting or extrusion processes (>120℃) are typically used, causing some materials to melt or undergo chemical reactions to form a dense structure. However, these extreme high-temperature conditions can lead to almost complete inactivation of beneficial microorganisms, the core bioactive components, rendering the product ineffective as a biofertilizer.

[0005] CN116621648B discloses a fertilizer that protects microbial strains using microencapsulation technology. The functional microbial strains are encapsulated in a complex core-shell structure and then physically mixed with organic materials. While this method effectively protects the microbial strains, the final fertilizer product is a simple mixture of components. The overall particle structure strength and slow-release performance are not strongly dependent, and the fundamental contradiction between "strength" and "microbial activity" in matrix-based fertilizers is not resolved.

[0006] Therefore, there is an urgent need in the field for bio-fertilizers that can be prepared under mild, low-temperature conditions, possessing both excellent mechanical strength to resist physical wear and effective protection of microbial activity, while achieving long-term, slow-release of fertilizer components. Based on the above, this invention proposes a biomass-based slow-release bio-fertilizer and its preparation method. Summary of the Invention

[0007] To address the technical challenge of achieving excellent mechanical strength, controllable slow-release performance of fertilizer components, high microbial survival rate, and a mild and environmentally friendly preparation process simultaneously in a single bio-fertilizer system, this invention proposes a biomass-based slow-release bio-fertilizer and its preparation method.

[0008] In a first aspect, the present invention provides a biomass-based slow-release bio-fertilizer, which adopts the following technical solution:

[0009] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20-40 parts of chemical fertilizer components, 30-50 parts of functional fiber matrix, 10-25 parts of inorganic cementitious material, 1-3 parts of compound synergist, 3-7 parts of microbial agent, and 1-3 parts of chelating agent.

[0010] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a mass ratio of 1-3:1. The solid-phase reactant is lightly calcined magnesium oxide and / or active calcium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate and / or magnesium dihydrogen phosphate.

[0011] Preferably, the fertilizer component is at least one of urea, monoammonium phosphate, and potassium sulfate.

[0012] Preferably, the functionalized fiber matrix is ​​prepared by the following steps:

[0013] Biomass raw materials are pretreated by steam explosion to obtain biomass fibers. Under the action of initiators and crosslinking agents, the biomass fibers are grafted and copolymerized with acrylic acid, acrylamide and functional monomers to obtain functionalized fiber matrix.

[0014] Preferably, the functional monomer is itaconic acid and / or 2-acrylamido-2-methylpropanesulfonic acid.

[0015] Preferably, the functional monomer comprises itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of 1:1-3.

[0016] Preferably, the functionalized fiber matrix is ​​prepared by the following method:

[0017] (1) Biomass raw materials are pretreated by steam explosion to obtain biomass fibers;

[0018] (2) Disperse biomass fibers in deionized water, heat to 60-80℃ under nitrogen protection, add initiator and stir to obtain reaction system;

[0019] (3) Dissolve acrylic acid, acrylamide, functional monomers and crosslinking agents in deionized water to obtain a monomer mixed solution;

[0020] (4) The monomer mixture solution is added dropwise to the reaction system at a uniform rate over 2 hours. After the addition is complete, the reaction is continued for 2-4 hours at a constant temperature. After the reaction is completed, the product is washed, dried and pulverized to obtain the functionalized fiber matrix.

[0021] Preferably, the biomass raw material in (1) is at least one of straw powder, rice husk powder, and corn cob powder.

[0022] Preferably, the biomass raw material in (1) is a mixture of straw powder, rice husk powder and corn cob powder in a weight ratio of 1:1:1.

[0023] Preferably, the steam explosion pretreatment parameters in (1) are as follows: pressure 1.5-2.5MPa, temperature 200-240℃, and treatment time 3-8min.

[0024] Preferably, the initiator in (2) is potassium persulfate (KPS), and the amount of initiator added is 0.5-1.5% of the biomass fiber mass.

[0025] Preferably, the mass ratio of acrylic acid, acrylamide, functional monomer, crosslinking agent and deionized water in (3) is 38-42:38-42:10:0.3-0.5:100.

[0026] Preferably, the crosslinking agent in (3) is N,N'-methylenebisacrylamide.

[0027] Preferably, the mass ratio of the monomer mixed solution to the reaction system in (4) is 1:3-4.

[0028] Preferably, the washing in (4) refers to washing the product with ethanol 2-3 times.

[0029] Preferably, the drying in (4) refers to the product after washing being vacuum dried at 50-70°C to constant weight.

[0030] Preferably, in (4), pulverization refers to pulverizing the dried product through an 80-100 mesh sieve.

[0031] Preferably, the composite synergist comprises polyaspartic acid and tannic acid in a mass ratio of 1:1-3.

[0032] Preferably, the microbial agent is prepared by spraying a protective liquid after mixing the agent with a carrier; the mass ratio of the agent, carrier and protective liquid is 0.5-1:2-5:0.5-1.

[0033] Preferably, the microbial agent is prepared by the following method:

[0034] Place the carrier into a mixer, evenly spread the bacterial agent on the diatomaceous earth, mix at 160-200 rpm for 15-20 minutes to obtain powder, and while stirring, spray the protective liquid onto the powder at a rate of 30-50 mL / min. After spraying, continue stirring for 5-10 minutes to obtain the microbial agent.

[0035] Preferably, the microbial agent is at least one of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, nitrogen-fixing bacteria, and plant growth-promoting bacteria.

[0036] Preferably, the bacterial agent is Bacillus megaterium.

[0037] Preferably, the carrier is diatomaceous earth and / or zeolite powder.

[0038] Preferably, the protective solution is a mixed aqueous solution of trehalose, glycerol and yeast extract.

[0039] Preferably, the mass ratio of trehalose, glycerol, yeast extract and deionized water is 5-15:5-15:2-8:62-88.

[0040] Preferably, the chelating agent is phytic acid and / or citric acid.

[0041] Secondly, the present invention provides a method for preparing biomass-based slow-release bio-fertilizer, which adopts the following technical solution:

[0042] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0043] S1. Mix the solid-phase reactants of fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material evenly to obtain composite coating powder; add the liquid-phase reactants of inorganic cementitious material and chelating agent to deionized water and stir until completely dissolved to obtain reactive adhesive solution.

[0044] S2. Start the disc granulator and add microbial agents as crystal nuclei at a temperature of 15-40℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder, the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles.

[0045] S3. Place the wet granules in an environment of 20-25℃ and relative humidity <60% for 30-40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0046] Preferably, the amount of deionized water used in step S1 is 10-15 times the total mass of the liquid phase reactants and chelating agents of the inorganic cementitious material.

[0047] Preferably, the alternating spraying of the reactive adhesive solution and the sprinkling of the composite coating powder in step S2 specifically refers to: spraying the reactive adhesive solution at a rate of 50-100 mL / min, while simultaneously sprinkling the composite coating powder at a rate of 200-300 g / min, with each spray lasting 5-10 seconds, followed by sprinkling the powder for 15-20 seconds, and repeating the cycle.

[0048] Preferably, the particle size of the wet particles formed in step S2 is in the range of 2-5 mm.

[0049] In summary, the present invention has the following beneficial effects:

[0050] 1. This invention uses both solid-phase and liquid-phase reactants as inorganic cementing materials and employs a low-temperature chemical self-curing system. Under mild conditions of 15-40℃, a robust crystalline network is generated through the in-situ reaction of the inorganic cementing materials, giving fertilizer particles a mechanical strength of over 8N, effectively preventing pulverization and damage during transportation. At the same time, the entire preparation process is carried out at low temperatures, ensuring that the activity of the microbial agent is not damaged, and the survival rate of the agent is over 89%.

[0051] 2. This invention utilizes the three-dimensional network structure of the functionalized fiber matrix and the solidified inorganic cementitious material to form a dual physical barrier, synergistically delaying the release of fertilizer components. The carboxyl and sulfonic acid functional groups on the fiber matrix further bind fertilizer component ions through chemical forces. The synergistic effect of these two components keeps the cumulative release rate of fertilizer below 60% over 28 days, achieving long-lasting slow release. Simultaneously, the functionalized fiber matrix imparts to the fertilizer a water absorption rate exceeding 100% and a water retention rate exceeding 85%.

[0052] 3. This invention uses a disc granulator, which can complete granulation and curing at low temperature through a simple alternating "spraying liquid-sprinkling powder" operation. It eliminates the need for high-temperature drying, extrusion, or complex coating equipment, significantly reducing energy consumption and equipment investment. The process is short, easy to industrialize, and in line with the development direction of green agriculture. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the embodiments.

[0054] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0055] The key raw materials used in this invention are sourced from the following sources:

[0056] Urea: CAS No. 57-13-6, purchased from Shanghai Chunyou Biotechnology Co., Ltd.;

[0057] Potassium persulfate: CAS No. 7727-21-1, purchased from Hengshui Jiamu Chemical Co., Ltd.;

[0058] Acrylic acid: CAS No. 79-10-7, purchased from Shandong Jinli Chemical Co., Ltd.;

[0059] Acrylamide: CAS No. 79-06-1, purchased from Shandong Guanchang Chemical Technology Co., Ltd.;

[0060] Itaconic acid: CAS No. 97-65-4, purchased from Jinan Jibin Chemical Co., Ltd.;

[0061] 2-Acrylamido-2-methylpropanesulfonic acid (AMPS): CAS No. 15214-89-8, purchased from Qingdao Tengyun Chemical Technology Co., Ltd.;

[0062] N,N'-Methylenebisacrylamide: CAS No. 110-26-9, purchased from Hubei Jiahuixingcheng Biotechnology Co., Ltd.;

[0063] Lightly calcined magnesium oxide: CAS No. 1309-48-4, purchased from Weifang Tianzhen Chemical Co., Ltd.;

[0064] Magnesium sulfate heptahydrate: CAS No. 10034-99-8, purchased from Chengdu Xinchangyuan Trading Co., Ltd.;

[0065] Citric acid: CAS No. 77-92-9, purchased from Suzhou Qiding Chemical Co., Ltd.;

[0066] Polyaspartic acid: CAS No. 181828-06-8, purchased from Nantong Runfeng Petrochemical Co., Ltd.;

[0067] Tannic acid: CAS No. 1401-55-4, purchased from Nanjing Puyi Biotechnology Co., Ltd.;

[0068] Bacillus megaterium: Model JDYBGJ100-1000, purchased from Pingdu Branch of Yuanda Life Science (Qingdao) Co., Ltd.

[0069] Diatomaceous earth: Model CY141210, purchased from Lingshou County Chengyang Mining Co., Ltd.;

[0070] Trehalose: CAS No. 99-20-7, purchased from Henan Rongshen Chemical Co., Ltd.;

[0071] Glycerin: CAS No. 56-81-5, purchased from Henan Juteng Chemical Products Co., Ltd.;

[0072] Yeast extract: CAS No. 8013-01-2, purchased from Shandong Pingju Biotechnology Co., Ltd.

[0073] Preparation Examples 1-3 and Comparative Preparation Examples 1-3 provide methods for preparing functionalized fiber matrices.

[0074] Preparation Example 1

[0075] The functionalized fiber matrix is ​​prepared by the following method:

[0076] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 1.5 MPa, the temperature at 200℃, and the treatment time at 8 min to obtain biomass fiber.

[0077] (2) Disperse biomass fiber in 4 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 60°C, add 0.5% of the biomass fiber mass of potassium persulfate, stir for 20 min to obtain the reaction system;

[0078] (3) Control the mass ratio of acrylic acid, acrylamide, functional monomer, N,N'-methylenebisacrylamide and deionized water to 38:42:10:0.3:100, dissolve acrylic acid, acrylamide, functional monomer (including itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid with a mass ratio of 1:1) and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution;

[0079] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:3. Add the monomer mixed solution to the reaction system at a uniform rate within 2 hours. After the addition is completed, keep warm and continue the reaction for 4 hours. After the reaction is completed, wash the product twice with ethanol, dry it under vacuum at 50°C to constant weight, pulverize it through an 80-mesh sieve, and obtain the functionalized fiber matrix.

[0080] Preparation Example 2

[0081] The functionalized fiber matrix is ​​prepared by the following method:

[0082] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 2MPa, the temperature at 220℃, and the treatment time at 5min to obtain biomass fiber.

[0083] (2) Disperse biomass fiber in 5 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 70°C, add 1% of the biomass fiber mass of potassium persulfate, stir for 15 min to obtain the reaction system;

[0084] (3) Control the mass ratio of acrylic acid, acrylamide, functional monomer, N,N'-methylenebisacrylamide and deionized water to 40:40:10:0.4:100, dissolve acrylic acid, acrylamide, functional monomer (including itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid with a mass ratio of 1:2) and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution;

[0085] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:3.5. Add the monomer mixed solution to the reaction system at a uniform rate over 2 hours. After the addition is complete, keep the temperature and continue the reaction for 3 hours. After the reaction is complete, wash the product twice with ethanol, dry it under vacuum at 60°C to constant weight, and pulverize it through a 90-mesh sieve to obtain the functionalized fiber matrix.

[0086] Preparation Example 3

[0087] The functionalized fiber matrix is ​​prepared by the following method:

[0088] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 2.5 MPa, the temperature at 240℃, and the treatment time at 3 min to obtain biomass fiber.

[0089] (2) Disperse biomass fiber in 6 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 80°C, add 1.5% of the biomass fiber mass of potassium persulfate, stir for 10 min to obtain the reaction system;

[0090] (3) Control the mass ratio of acrylic acid, acrylamide, functional monomer, N,N'-methylenebisacrylamide and deionized water to be 42:38:10:0.5:100. Dissolve acrylic acid, acrylamide, functional monomer (including itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid with a mass ratio of 1:3) and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution.

[0091] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:4. Add the monomer mixed solution to the reaction system at a uniform rate within 2 hours. After the addition is completed, keep warm and continue the reaction for 2 hours. After the reaction is completed, wash the product with ethanol 3 times, dry it under vacuum at 70°C to constant weight, pulverize it through a 100-mesh sieve, and obtain the functionalized fiber matrix.

[0092] Comparative Preparation Example 1

[0093] Compared with Preparation Example 1, the difference is that only itaconic acid was selected as the functional monomer, as detailed below:

[0094] The functionalized fiber matrix is ​​prepared by the following method:

[0095] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 1.5 MPa, the temperature at 200℃, and the treatment time at 8 min to obtain biomass fiber.

[0096] (2) Disperse biomass fiber in 4 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 60°C, add 0.5% of the biomass fiber mass of potassium persulfate, stir for 20 min to obtain the reaction system;

[0097] (3) Control the mass ratio of acrylic acid, acrylamide, itaconic acid, N,N'-methylenebisacrylamide and deionized water to 38:42:10:0.3:100, dissolve acrylic acid, acrylamide, itaconic acid and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution;

[0098] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:3. Add the monomer mixed solution to the reaction system at a uniform rate within 2 hours. After the addition is completed, keep warm and continue the reaction for 4 hours. After the reaction is completed, wash the product twice with ethanol, dry it under vacuum at 50°C to constant weight, pulverize it through an 80-mesh sieve, and obtain the functionalized fiber matrix.

[0099] Comparative Preparation Example 2

[0100] Compared with Preparation Example 1, Preparation Example 2 differs in that the functional monomer used is only 2-acrylamido-2-methylpropanesulfonic acid, as detailed below:

[0101] The functionalized fiber matrix is ​​prepared by the following method:

[0102] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 1.5 MPa, the temperature at 200℃, and the treatment time at 8 min to obtain biomass fiber.

[0103] (2) Disperse biomass fiber in 4 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 60°C, add 0.5% of the biomass fiber mass of potassium persulfate, stir for 20 min to obtain the reaction system;

[0104] (3) Control the mass ratio of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide and deionized water to 38:42:10:0.3:100, dissolve acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution;

[0105] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:3. Add the monomer mixed solution to the reaction system at a uniform rate within 2 hours. After the addition is completed, keep warm and continue the reaction for 4 hours. After the reaction is completed, wash the product twice with ethanol, dry it under vacuum at 50°C to constant weight, pulverize it through an 80-mesh sieve, and obtain the functionalized fiber matrix.

[0106] Comparative preparation example 3

[0107] Compared with Preparation Example 1, Preparation Example 3 differs in that the functional monomers are replaced with acrylic acid and acrylamide, as follows:

[0108] The functionalized fiber matrix is ​​prepared by the following method:

[0109] (1) Mix straw powder, rice husk powder and corn cob powder in a mass ratio of 1:1:1, and perform steam explosion pretreatment. Control the treatment pressure at 1.5 MPa, the temperature at 200℃, and the treatment time at 8 min to obtain biomass fiber.

[0110] (2) Disperse biomass fiber in 4 times its mass of deionized water, purge with nitrogen for 30 min to remove oxygen, heat to 60°C, add 0.5% of the biomass fiber mass of potassium persulfate, stir for 20 min to obtain the reaction system;

[0111] (3) Control the mass ratio of acrylic acid, acrylamide, N,N'-methylenebisacrylamide and deionized water to 42:48:0.3:100, dissolve acrylic acid, acrylamide and N,N'-methylenebisacrylamide in deionized water to obtain a monomer mixed solution;

[0112] (4) Control the mass ratio of monomer mixed solution and reaction system to 1:3. Add the monomer mixed solution to the reaction system at a uniform rate within 2 hours. After the addition is completed, keep warm and continue the reaction for 4 hours. After the reaction is completed, wash the product twice with ethanol, dry it under vacuum at 50°C to constant weight, pulverize it through an 80-mesh sieve, and obtain the functionalized fiber matrix.

[0113] Examples 1-3 provide a biomass-based slow-release bio-fertilizer and its preparation method.

[0114] Example 1

[0115] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0116] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0117] The functionalized fiber matrix was prepared in Preparation Example 1;

[0118] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a 1:1 mass ratio; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0119] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0120] Microbial inoculants are prepared by the following methods:

[0121] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0122] The chelating agent is citric acid.

[0123] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0124] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 10 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0125] S2. Start the disc granulator and add microbial agent as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder (spraying the reactive adhesive solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0126] S3. Place the wet granules in an environment of 20℃ and 55% relative humidity for 40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0127] Example 2

[0128] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 30 parts of chemical fertilizer components, 40 parts of functionalized fiber matrix, 18 parts of inorganic cementitious material, 2 parts of compound synergist, 5 parts of microbial agent, and 2 parts of chelating agent.

[0129] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0130] The functionalized fiber matrix was prepared in Preparation Example 2;

[0131] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a mass ratio of 2:1; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0132] The compound synergist consists of polyaspartic acid and tannic acid in a mass ratio of 1:2;

[0133] Microbial inoculants are prepared by the following methods:

[0134] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.8:3.5:0.8. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 180 rpm for 18 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 40 mL / min. After spraying, stirring was continued for 8 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 10:10:5:70.

[0135] The chelating agent is citric acid.

[0136] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0137] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 12.5 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0138] S2. Start the disc granulator and add microbial agent as crystal nuclei at a controlled temperature of 28℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder (spraying the reactive adhesive solution at a rate of 75mL / min and sprinkling the composite coating powder at a rate of 250g / min, each spray lasting 8s, followed by sprinkling powder for 18s, and repeating the cycle), the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0139] S3. Place the wet granules in an environment of 22℃ and 50% relative humidity for 35 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0140] Example 3

[0141] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 40 parts of chemical fertilizer components, 50 parts of functionalized fiber matrix, 25 parts of inorganic cementitious material, 3 parts of compound synergist, 7 parts of microbial agent, and 3 parts of chelating agent.

[0142] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0143] The functionalized fiber matrix was prepared in Preparation Example 3;

[0144] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a mass ratio of 3:1; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0145] The compound synergist consists of polyaspartic acid and tannic acid in a mass ratio of 1:3;

[0146] Microbial inoculants are prepared by the following methods:

[0147] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 1:5:1. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 200 rpm for 15 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 50 mL / min. After spraying, stirring was continued for 5 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 15:15:8:88.

[0148] The chelating agent is citric acid.

[0149] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0150] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 15 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0151] S2. Start the disc granulator and add microbial agents as crystal nuclei at a controlled temperature of 40℃. By alternately spraying the reaction binder solution and sprinkling the composite coating powder (spraying the reaction binder solution at a rate of 100mL / min and sprinkling the composite coating powder at a rate of 300g / min, each spray lasting 5s, followed by sprinkling powder for 15s, and repeating the cycle), the granules grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet granules with a particle size in the range of 2-5mm; S3. Let the wet granules stand and cure in an environment of 25℃ and 57% relative humidity for 30h until the curing reaction is complete, thus obtaining biomass-based slow-release bio-fertilizer.

[0152] To verify the comprehensive performance of the biomass-based slow-release bio-fertilizer provided by this invention, comparative examples 1-6 were set up, wherein:

[0153] Comparative Example 1

[0154] Comparative Example 1 is the same as Example 1, except that the functionalized fiber matrix was prepared using Comparative Preparation Example 1. Details are as follows:

[0155] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0156] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0157] The functionalized fiber matrix was prepared by comparative preparation example 1;

[0158] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a 1:1 mass ratio; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0159] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0160] Microbial inoculants are prepared by the following methods:

[0161] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0162] The chelating agent is citric acid.

[0163] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0164] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 10 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0165] S2. Start the disc granulator and add microbial agent as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder (spraying the reactive adhesive solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0166] S3. Place the wet granules in an environment of 20℃ and 55% relative humidity for 40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0167] Comparative Example 2

[0168] Comparative Example 2 is the same as Example 1, except that the functionalized fiber matrix was prepared from Comparative Preparation Example 2. Details are as follows:

[0169] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0170] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0171] The functionalized fiber matrix was prepared in Comparative Preparation Example 2;

[0172] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a 1:1 mass ratio; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0173] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0174] Microbial inoculants are prepared by the following methods:

[0175] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0176] The chelating agent is citric acid.

[0177] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0178] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 10 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0179] S2. Start the disc granulator and add microbial agent as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder (spraying the reactive adhesive solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0180] S3. Place the wet granules in an environment of 20℃ and 55% relative humidity for 40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0181] Comparative Example 3

[0182] Comparative Example 3 is the same as Example 1, except that the functionalized fiber matrix was prepared from Comparative Example 3. Details are as follows:

[0183] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0184] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0185] The functionalized fiber matrix was prepared by comparative preparation example 3;

[0186] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a 1:1 mass ratio; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0187] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0188] Microbial inoculants are prepared by the following methods:

[0189] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0190] The chelating agent is citric acid.

[0191] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0192] S1. Mix the fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material solid phase reactants evenly to obtain composite coating powder; add the inorganic cementitious material liquid phase reactants and chelating agent to deionized water (the amount of deionized water is 10 times the total mass of the inorganic cementitious material liquid phase reactants and chelating agent), stir until completely dissolved to obtain a reactive adhesive solution;

[0193] S2. Start the disc granulator and add microbial agents as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reaction binder solution and sprinkling the composite coating powder (spraying the reaction binder solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the granules grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet granules with a particle size in the range of 2-5mm; S3. Let the wet granules stand and cure in an environment of 20℃ and 55% relative humidity for 40h until the curing reaction is complete, thus obtaining biomass-based slow-release bio-fertilizer.

[0194] Comparative Example 4

[0195] Comparative Example 4 is the same as Example 1, except that the inorganic cementitious material used is only lightly calcined magnesium oxide, a solid reactant. Details are as follows:

[0196] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0197] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0198] The functionalized fiber matrix was prepared in Preparation Example 1;

[0199] The inorganic cementing material is lightly calcined magnesium oxide;

[0200] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0201] Microbial inoculants are prepared by the following methods:

[0202] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0203] The chelating agent is citric acid.

[0204] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0205] S1. Mix fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material evenly to obtain composite coating powder; add chelating agent to deionized water (the amount of deionized water is 10 times the total mass of chelating agent) and stir until completely dissolved to obtain reactive adhesive solution.

[0206] S2. Start the disc granulator and add microbial agents as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reaction binder solution and sprinkling the composite coating powder (spraying the reaction binder solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the granules grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet granules with a particle size in the range of 2-5mm; S3. Let the wet granules stand and cure in an environment of 20℃ and 55% relative humidity for 40h until the curing reaction is complete, thus obtaining biomass-based slow-release bio-fertilizer.

[0207] Comparative Example 5

[0208] Comparative Example 5 is the same as Example 1, except that the inorganic cementing material used is only the liquid-phase reactant magnesium sulfate heptahydrate. Details are as follows:

[0209] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0210] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0211] The functionalized fiber matrix was prepared in Preparation Example 1;

[0212] The inorganic cementing material is magnesium sulfate heptahydrate;

[0213] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0214] Microbial inoculants are prepared by the following methods:

[0215] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0216] The chelating agent is citric acid.

[0217] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0218] S1. Mix fertilizer components, functional fiber matrix and composite synergist evenly to obtain composite coating powder; add inorganic cementitious material and chelating agent to deionized water (the amount of deionized water is 10 times the total mass of inorganic cementitious material and chelating agent), stir until completely dissolved to obtain reactive adhesive solution;

[0219] S2. Start the disc granulator and add microbial agent as crystal nuclei at a controlled temperature of 15℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder (spraying the reactive adhesive solution at a rate of 50mL / min and sprinkling the composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the particles grow layer by layer and solidify simultaneously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0220] S3. Place the wet granules in an environment of 20℃ and 55% relative humidity for 40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0221] Comparative Example 6

[0222] Comparative Example 6 is the same as Example 1, except that it uses a traditional one-step mixing physical granulation method. Details are as follows:

[0223] A biomass-based slow-release bio-fertilizer comprises the following raw materials in parts by weight: 20 parts of chemical fertilizer components, 30 parts of functional fiber matrix, 10 parts of inorganic cementitious material, 1 part of compound synergist, 3 parts of microbial agent, and 1 part of chelating agent.

[0224] The fertilizer components include urea, monoammonium phosphate, and potassium sulfate in a mass ratio of 1:1:1.

[0225] The functionalized fiber matrix was prepared in Preparation Example 1;

[0226] The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a 1:1 mass ratio; the solid-phase reactant is lightly calcined magnesium oxide; the liquid-phase reactant is magnesium sulfate heptahydrate.

[0227] The compound synergist consists of polyaspartic acid and tannic acid in a 1:1 mass ratio;

[0228] Microbial inoculants are prepared by the following methods:

[0229] The mass ratio of Bacillus megaterium, diatomaceous earth, and protective solution was controlled at 0.5:2:0.5. Diatomaceous earth was added to a mixer, and Bacillus megaterium was evenly sprinkled on the top layer of diatomaceous earth. The mixture was stirred at 160 rpm for 20 minutes to obtain powder. While stirring, the protective solution was sprayed onto the powder at a rate of 30 mL / min. After spraying, stirring was continued for 10 minutes to obtain the microbial agent. The protective solution was a mixed aqueous solution of trehalose, glycerol, and yeast extract, and the mass ratio of trehalose, glycerol, yeast extract, and deionized water was 5:5:2:62.

[0230] The chelating agent is citric acid.

[0231] A method for preparing a biomass-based slow-release bio-fertilizer includes the following steps:

[0232] S1. Mix fertilizer components, functional fiber matrix, composite synergist, inorganic cementitious material, chelating agent and microbial agent evenly to obtain composite coating powder;

[0233] S2. Start the disc granulator and control the temperature at 15℃. By alternately spraying deionized water (the amount of deionized water is 10 times the total mass of the liquid phase reactants and chelating agents of the inorganic cementitious material) and sprinkling composite coating powder (spraying deionized water at a rate of 50mL / min and sprinkling composite coating powder at a rate of 200g / min, each spray lasting 10s, followed by sprinkling powder for 20s, and repeating the cycle), the particles grow layer by layer and solidify synchronously through a low-temperature chemical self-curing reaction during the rolling process, forming wet particles with a particle size in the range of 2-5mm.

[0234] S3. Place the wet granules in an environment of 20℃ and 55% relative humidity for 40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.

[0235] The comprehensive performance of the biomass-based slow-release bio-fertilizers prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was tested respectively.

[0236] 1. Test of slow-release performance of fertilizer components

[0237] The testing was conducted according to GB / T 23348-2009 "Slow-Release Fertilizers". Specifically: First, the total nitrogen content (w0, %) in the fertilizer sample was determined using the Kjeldahl method, and a total nitrogen standard curve was established using alkaline potassium persulfate digestion-ultraviolet spectrophotometry to obtain the concentration-absorbance regression equation. Then, 5.00g of fertilizer granules was accurately weighed and placed in a 100-mesh nylon mesh bag, which was then completely immersed in a beaker containing 500mL of deionized water and incubated at a constant temperature of 25℃. At predetermined time points of 1, 3, 7, 14, 28, and 56 days, 5.0mL of solution was accurately drawn from the supernatant of the beaker as the test sample, and an equal volume (5.0mL) of deionized water was immediately added to the beaker to maintain a constant soaking solution volume. The extracted sample solution was appropriately diluted according to the estimated concentration, and then treated using the alkaline potassium persulfate digestion method. The corrected absorbance was measured using a UV-Vis spectrophotometer, and the total nitrogen concentration (C0) in the soaking solution at that time point was calculated by substituting it into the standard curve regression equation. N Finally, according to the formula R that considers the cumulative amount of each sampling... N (%) = [(C) N The total cumulative nitrogen release rate at each time point is calculated as follows: (×500mL) + (total sampled nitrogen) / (5.00g×w0×1000)×100%.

[0238] 2. Particle structure stability test

[0239] 2.1 Particle compressive strength test

[0240] The compressive strength of granules was tested according to the method for determining granular compressive strength in GB / T 8576-2010 "Compound Fertilizers". Specifically: First, the fertilizer sample needs to be pretreated. Granules with a diameter of 2.00-4.00 mm, intact appearance, and no obvious defects are selected as test samples through a standard sieve. Then, 50 granules are randomly selected from this batch and measured individually using a physical property testing instrument. Finally, each fertilizer granule is placed stably in the center of the lower pressure plate of the testing instrument. The instrument is started, and the upper pressure plate applies uniaxial compression to the granule at a constant loading speed of 10 mm / min until the granule breaks. The instrument automatically records and reads the maximum load value that the granule can withstand at the moment of breakage. This operation is repeated until all 50 granules are tested. Finally, the arithmetic mean of these 50 load values ​​is calculated, and the standard deviation is added. This average value is the final granular compressive strength of the sample.

[0241] 2.2 Determination of particle breakage rate

[0242] Take 50 granules from each fertilizer sample and place them in a 250mL Erlenmeyer flask. After capping, place the flask in a reciprocating shaker and shake at a frequency of 150 times per minute. After 10 minutes, remove the flask and observe whether the fertilizer sample granules have broken. The granule breakage rate is calculated as follows: (Number of intact granules before shaking - Number of intact granules after shaking) / Number of intact granules before shaking × 100%. The breakage rate of each fertilizer sample is then determined.

[0243] 3. Water absorption and retention performance test

[0244] Accurately weigh 10g of fertilizer sample granules, immerse them fully in deionized water until saturated, drain the surface moisture, and weigh them. Calculate the water absorption rate = (saturated weight - initial weight) / initial weight × 100%. Then, place the water-saturated sample in an environment of 25℃ and 60% relative humidity to allow it to lose water naturally. Weigh it after 24 hours and calculate the water retention rate = (weight after 24 hours - initial dry weight) / (saturated weight - initial dry weight) × 100%.

[0245] 4. Microbial activity assay

[0246] The effective viable count was determined according to GB / T 20291-2006, "Determination of Effective Viable Bacteria Count in Microbial Fertilizers". Specifically: First, at the start of the experiment (day 0), initial samples from each example and comparative group were taken, and the initial effective viable count was determined using the dilution plating method, denoted as N0 (CFU / g). Subsequently, three parallel 1.00g samples were accurately weighed from each group and placed in sterile petri dishes (with the lids slightly open to ensure air circulation). These petri dishes were then placed in a pre-set and stably operating constant temperature and humidity incubator. The incubator conditions were set to: temperature 40±2℃, relative humidity 80±5%, for a 60-day continuous accelerated aging treatment. At the end of day 60, all samples were removed, and the effective viable count after aging was determined using the dilution plating method, denoted as N. 60 (CFU / g). Finally, according to the formula, microbial survival rate (%) = (N... 60 The microbial survival rate of each sample was calculated by multiplying ( / N0) by 100%, and the average value of the three parallel samples was taken as the final result.

[0247] The test results are shown in Table 1-3:

[0248] Table 1. Test data on the slow-release performance of fertilizer components in biomass-based slow-release bio-fertilizers in Examples 1-3 and Comparative Examples 1-6

[0249] Test Project Fertilizer component release rate (Day 1) Fertilizer component release rate (day 3) Fertilizer component release rate (day 7) Fertilizer component release rate (day 14) Fertilizer component release rate (day 28) Fertilizer component release rate (day 56) Example 1 7.8% 15.2% 27.5% 43.8% 55.4% 61.0% Example 2 6.5% 12.8% 23.1% 38.5% 51.2% 63.5% Example 3 5.1% 10.5% 19.6% 33.7% 48.9% 65.8% Comparative Example 1 24.6% 38.8% 55.2% 68.4% 75.1% 78.3% Comparative Example 2 19.5% 31.2% 48.9% 61.5% 70.3% 74.5% Comparative Example 3 48.2% 65.7% 83.1% 89.5% 91.2% 91.8% Comparative Example 4 10.3% 19.8% 33.6% 50.1% 68.5% 75.4% Comparative Example 5 9.5% 18.1% 31.7% 48.2% 66.9% 74.1% Comparative Example 6 12.8% 23.5% 38.9% 55.6% 65.8% 70.2%

[0250] Table 2. Test data on particle structure stability and water absorption and retention performance of biomass-based slow-release biofertilizers in Examples 1-3 and Comparative Examples 1-6.

[0251] Test Project Compressive strength (N) Fracturing rate (%) Water absorption rate (%) 24-hour water retention rate (%) Example 1 8.34 1 105 88 Example 2 9.62 0 128 91 Example 3 10.85 0 145 93 Comparative Example 1 6.15 9 62 53 Comparative Example 2 6.88 7 81 72 Comparative Example 3 2.53 35 38 31 Comparative Example 4 2.11 42 98 80 Comparative Example 5 1.95 48 93 83 Comparative Example 6 7.51 4 95 85

[0252] Table 3. Microbial activity assay data of biomass-based slow-release biofertilizers in Examples 1-3 and Comparative Examples 1-6

[0253] Test Project <![CDATA[Initial viable bacteria count N0 (CFU / g)]]> <![CDATA[The viable count N after aging 60 (CFU / g)]]> Microbial survival rate (%) Example 1 <![CDATA[4.8×10 7 ]]> <![CDATA[4.3×10 7 ]]> 89.6 Example 2 <![CDATA[4.9×10 7 ]]> <![CDATA[4.5×10 7 ]]> 91.8 Example 3 <![CDATA[5.1×10 7 ]]> <![CDATA[4.7×10 7 ]]> 92.2 Comparative Example 1 <![CDATA[4.7×10 7 ]]> <![CDATA[3.8×10 7 ]]> 80.9 Comparative Example 2 <![CDATA[4.8×10 7 ]]> <![CDATA[4.0×10 7 ]]> 83.3 Comparative Example 3 <![CDATA[4.6×10 7 ]]> <![CDATA[3.1×10 7 ]]> 67.4 Comparative Example 4 <![CDATA[4.9×10 7 ]]> <![CDATA[4.1×10 7 ]]> 83.7 Comparative Example 5 <![CDATA[4.8×10 7 ]]> <![CDATA[4.1×10 7 ]]> 85.4 Comparative Example 6 <![CDATA[5.0×10 7 ]]> <![CDATA[3.1×10 7 ]]> 62.0

[0254] As shown in Tables 1-3, the biomass-based slow-release bio-fertilizers prepared in Examples 1-3 of this invention, while maintaining high mechanical strength and excellent microbial survival rate, also possess controllable slow-release properties of fertilizer components and excellent water absorption and retention capacity, with comprehensive performance far exceeding that of Comparative Examples 1-6.

[0255] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A biomass-based slow-release bio-fertilizer, characterized in that, The raw materials include the following parts by weight: 20-40 parts of fertilizer components, 30-50 parts of functional fiber matrix, 10-25 parts of inorganic cementitious material, 1-3 parts of compound synergist, 3-7 parts of microbial agent, and 1-3 parts of chelating agent. The inorganic cementitious material comprises a solid-phase reactant and a liquid-phase reactant in a mass ratio of 1-3:1, wherein the solid-phase reactant is lightly calcined magnesium oxide and / or active calcium oxide. The liquid-phase reactants are magnesium sulfate heptahydrate and / or magnesium dihydrogen phosphate.

2. The biomass-based slow-release bio-fertilizer according to claim 1, characterized in that, The fertilizer components are at least one of urea, monoammonium phosphate, and potassium sulfate.

3. The biomass-based slow-release bio-fertilizer according to claim 1, characterized in that, The functionalized fiber matrix is ​​prepared by the following steps: Biomass raw materials are pretreated by steam explosion to obtain biomass fibers. Under the action of initiators and crosslinking agents, the biomass fibers are grafted and copolymerized with acrylic acid, acrylamide and functional monomers to obtain functionalized fiber matrix.

4. The biomass-based slow-release bio-fertilizer according to claim 3, characterized in that, The functional monomer is itaconic acid and / or 2-acrylamido-2-methylpropanesulfonic acid.

5. The biomass-based slow-release bio-fertilizer according to claim 4, characterized in that, The functional monomer is composed of itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of 1:1-3.

6. The biomass-based slow-release bio-fertilizer according to claim 1, characterized in that, The composite synergist comprises polyaspartic acid and tannic acid in a mass ratio of 1:1-3.

7. The biomass-based slow-release bio-fertilizer according to claim 1, characterized in that, The microbial agent is prepared by spraying a protective liquid after mixing the agent with a carrier; the mass ratio of the agent, carrier and protective liquid is 0.5-1:2-5:0.5-1.

8. The biomass-based slow-release bio-fertilizer according to claim 7, characterized in that, The bacterial agent is at least one of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, nitrogen-fixing bacteria, and plant growth-promoting bacteria; the carrier is diatomaceous earth and / or zeolite powder; and the protective solution is a mixed aqueous solution of trehalose, glycerol, and yeast extract.

9. The biomass-based slow-release bio-fertilizer according to claim 1, characterized in that, The chelating agent is phytic acid and / or citric acid.

10. A method for preparing a biomass-based slow-release bio-fertilizer according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix the solid-phase reactants of fertilizer components, functional fiber matrix, composite synergist and inorganic cementitious material evenly to obtain composite coating powder; add the liquid-phase reactants of inorganic cementitious material and chelating agent to deionized water and stir until completely dissolved to obtain reactive adhesive solution. S2. Start the disc granulator and add microbial agents as crystal nuclei at a temperature of 15-40℃. By alternately spraying the reactive adhesive solution and sprinkling the composite coating powder, the particles grow layer by layer and solidify simultaneously through a chemical self-curing reaction during the rolling process, forming wet particles. S3. Place the wet granules in an environment of 20-25℃ and relative humidity <60% for 30-40 hours until the solidification reaction is complete, and the biomass-based slow-release bio-fertilizer is obtained.