Biochar carrier-based apple water and fertilizer slow-release synergistic preparation and preparation method thereof
Patent Information
- Application Number
- CN202610937648.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-26
- Publication Date
- 2026-08-28
AI Technical Summary
[0004]本发明提供了基于生物炭载体的苹果水肥缓释协同制剂及其制备方法，解决了传统肥料留不住、释放快、利用率低的技术问题，配方包含了氮、磷、钾大量元素，以及通过改性引入的中微量元素，满足苹果树全生育期需求
0、本发明中加入氮掺杂碳纳米纤维，起到了支撑作用，穿插在肥料颗粒内部形成三维网络骨架。显著提高了颗粒的机械强度，防止在运输和施用过程中破碎。氮掺杂碳纳米纤维具有优异的亲水性和导电性，能在颗粒内部构建微细管系统，加速水分向颗粒内部渗透，同时为养分离子的传输提供高速通道，解决传统缓释肥释放太慢的问题。通过增强纳米骨架，使得苹果水肥缓释协同制剂具有优异的物理性能。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of water and fertilizer slow-release technology, and more specifically, to a biochar-based slow-release synergistic formulation for apples and its preparation method. Background Technology
[0002] Apple trees have a long growth cycle, and their nutrient requirements fluctuate dramatically throughout the budding, flowering, fruit setting, and fruit enlargement stages. During critical periods of nutrient demand, such as spring budding and summer fruit enlargement, the release rate of some long-acting fertilizers may not keep up with the tree's explosive needs, resulting in small fruit or weak tree vigor. During periods of low nutrient demand (such as after harvest or dormancy), fertilizers may continue to be released, leading to excessive vegetative growth, decreased cold resistance, and even environmental pollution. Most water-based fertilizer formulations have a single release mechanism, making it difficult to intelligently regulate based on biological signals such as soil pH, enzyme activity, or root exudates. For example, during periods of soil drought, fertilizer release relying on water diffusion slows down, while the tree may need more nutrients to regulate osmotic pressure, leading to increased nutrient deficiency during drier conditions.
[0003] In existing technologies, many biodegradable polymer coatings (such as pure PVA films and starch-based films) have poor mechanical strength. Under the complex alternating wet and dry conditions in the field, the coatings are prone to absorbing water, swelling, rupturing, or prematurely degrading, leading to the failure of controlled-release function. If biochar is used as the core for coating treatment, due to the porous and rough surface of biochar, the polymer coating may be difficult to form a uniform and dense protective layer, or it may easily fall off after absorbing water and swelling, resulting in the failure of controlled release. Summary of the Invention
[0004] This invention provides a biochar-based slow-release fertilizer synergistic formulation for apples and its preparation method, which solves the technical problems of traditional fertilizers being unable to retain nutrients, releasing them too quickly, and having low utilization rates. The formulation contains macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients introduced through modification, meeting the needs of apple trees throughout their entire growth period.
[0005] In a first aspect, the present invention provides a method for preparing a biochar-based slow-release synergistic formulation for apples, comprising the following steps: (1) Polyacrylonitrile is used as a carbon source precursor, dissolved in dimethylformamide solvent, and urea or melamine is added as a nitrogen source. The mixture is spun into a nanofiber membrane using an electrospinning machine, and then pre-oxidized and carbonized to obtain nitrogen-doped carbon nanofibers. (2) The natural attapulgite ore is crushed and calcined at 300-400℃ for 2-3 hours. The thermally activated attapulgite is dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is added. The mixture is stirred and reacted at 60-80℃ for 6-7 hours to obtain aminated attapulgite. (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid. (4) Mix the functional bacterial agent with biochar, and use the porous nature of biochar to adsorb the bacterial solution. Dry it in the shade at 20-30℃, add urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers, then add aminated attapulgite, put it into a mixer and stir thoroughly for 20-30 minutes to obtain dry powder material. (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0006] Preferably, in step (1), the mass ratio of the carbon source precursor to the nitrogen source is 7~11:1~2.
[0007] Preferably, in step (1), the pre-oxidation and carbonization conditions are: first, pre-oxidation stabilization at 250-300°C in an air atmosphere, and then carbonization at 950-1050°C for 2-3 hours under nitrogen protection.
[0008] Preferably, in step (1), the nitrogen content in the nitrogen-doped carbon nanofibers is 5-10%.
[0009] Preferably, in step (2), the amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added is 5-8%.
[0010] Preferably, in step (3), the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 2-5:1-3.
[0011] Preferably, in step (4), the functional microbial agent is selected from at least one of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus megaterium, and Trichoderma harzianum.
[0012] Preferably, in step (4), the mass ratio of urea, monoammonium phosphate and potassium sulfate is 2-3:1:1-2; the amount of biochar added is 25-45%; and the amount of functional microbial agent added is 20-32%.
[0013] Preferably, in step (4), the amount of aminated attapulgite added is 10-18%; and the amount of nitrogen-doped carbon nanofibers added is 1-4%.
[0014] Secondly, the present invention provides an apple water-fertilizer slow-release synergistic formulation based on a biochar carrier prepared by the above preparation method.
[0015] Preferably, the particle size of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier is 2-6 mm.
[0016] In summary, the present invention has the following beneficial effects: 0. In this invention, nitrogen-doped carbon nanofibers are incorporated, providing support and forming a three-dimensional network framework within the fertilizer granules. This significantly improves the mechanical strength of the granules, preventing breakage during transportation and application. The nitrogen-doped carbon nanofibers possess excellent hydrophilicity and conductivity, enabling the construction of microtubule systems within the granules. This accelerates water penetration into the granules and provides high-speed channels for nutrient molecule transport, solving the problem of slow release in traditional slow-release fertilizers. By enhancing the nanoframework, the apple water-fertilizer slow-release synergistic formulation exhibits superior physical properties.
[0017] 2. In this invention, aminated attapulgite carries a positive charge, specifically targeting anionic nutrients such as phosphate. Phosphorus in traditional fertilizers is easily fixed and rendered ineffective by calcium, magnesium, iron, and aluminum ions in the soil. Aminated attapulgite, through electrostatic adsorption, binds phosphate, preventing its fixation by the soil and significantly improving phosphorus availability. Modified γ-polyglutamic acid carries a negative charge / amphoteric charge, targeting cationic nutrients such as ammonium and potassium ions. Its abundant carboxyl groups can chelate cations. This dual-absorption mechanism allows the fertilizer to intelligently adjust its release rate according to the concentration difference in the soil solution, truly achieving supply when needed and storage when not needed. Modified γ-polyglutamic acid is a superabsorbent resin capable of absorbing hundreds of times its own weight in water. Both biochar and aminated attapulgite possess well-developed porous structures. The resulting apple water-fertilizer slow-release synergistic formulation, after being applied to the soil, can absorb sufficient water like a sponge during rainfall or irrigation, and slowly release it for root absorption during drought. This not only reduces the frequency of irrigation but also maintains a moist environment in the rhizosphere soil, improving the apple trees' drought resistance.
[0018] 3. The apple water-fertilizer slow-release synergistic formulation prepared in this invention contains macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients introduced through modification. Attapulgite soil is rich in micronutrients, meeting the needs of apple trees throughout their entire growth cycle. The porous structure of biochar protects the microbial strains of the functional agent from damage by adverse external environments. The organic carbon on the surface of the biochar can serve as an auxiliary carbon source for microorganisms, promoting microbial reproduction. Activated functional bacteria can secrete plant growth hormones (such as IAA) and organic acids, further dissolving phosphorus and potassium fixed in the soil and inhibiting soil-borne diseases, achieving a dual effect of fertilizer and pesticide. Due to the stable nutrient release, it avoids excessive vegetative growth caused by nitrogen excess or premature aging caused by late-stage nutrient deficiency in fruit trees. This helps promote apple flower bud differentiation, improve fruit sugar content, firmness, and color, and reduce the occurrence of physiological diseases such as bitter pit.
[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Detailed Implementation
[0020] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.
[0021] Example Example 1 A method for preparing a biochar-based slow-release fertilizer synergistic formulation for apples includes the following steps: (1) Polyacrylonitrile was used as a carbon source precursor and dissolved in dimethylformamide solvent. Urea or melamine was added as a nitrogen source. The mixture was spun into a nanofiber membrane using an electrospinning machine. Pre-oxidation and carbonization were performed to obtain nitrogen-doped carbon nanofibers. The mass ratio of carbon source precursor to nitrogen source was 8:1. The pre-oxidation and carbonization conditions were: first, pre-oxidation and stabilization were performed at 250°C in an air atmosphere, and then carbonization was performed at 1050°C for 2 hours under nitrogen protection. The nitrogen content in the nitrogen-doped carbon nanofibers was 6%.
[0022] (2) The natural attapulgite ore was crushed and calcined at 300°C for 2 hours. The thermally activated attapulgite was dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added. The mixture was stirred and reacted at 60°C for 6 hours to obtain aminated attapulgite. The amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added was 6%.
[0023] (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid; the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 3:1.
[0024] (4) The functional bacterial agent was mixed with biochar, and the porous nature of the biochar was used to adsorb the bacterial solution. The mixture was then air-dried at 20°C. Urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers were added, followed by aminated attapulgite. The mixture was then placed in a mixer and stirred thoroughly for 20 minutes to obtain a dry powder. The functional bacterial agent was selected from Bacillus subtilis and Bacillus amyloliquefaciens. The mass ratio of urea, monoammonium phosphate and potassium sulfate was 2:1:2. The amount of biochar added was 30%, the amount of functional bacterial agent added was 24%, the amount of aminated attapulgite added was 12%, and the amount of nitrogen-doped carbon nanofibers added was 2%.
[0025] (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0026] Example 2 A method for preparing a biochar-based slow-release fertilizer synergistic formulation for apples includes the following steps: (1) Polyacrylonitrile was used as a carbon source precursor and dissolved in dimethylformamide solvent. Urea or melamine was added as a nitrogen source. The mixture was spun into a nanofiber membrane using an electrospinning machine. Pre-oxidation and carbonization were performed to obtain nitrogen-doped carbon nanofibers. The mass ratio of carbon source precursor to nitrogen source was 7:1. The pre-oxidation and carbonization conditions were: first, pre-oxidation and stabilization were performed at 250°C in an air atmosphere, and then carbonization was performed at 1050°C for 2 hours under nitrogen protection. The nitrogen content in the nitrogen-doped carbon nanofibers was 5%.
[0027] (2) The natural attapulgite ore was crushed and calcined at 300°C for 2 hours. The thermally activated attapulgite was dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added. The mixture was stirred at 60°C for 6 hours to obtain aminated attapulgite. The amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added was 5%.
[0028] (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid; the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 2:1.
[0029] (4) The functional bacterial agent was mixed with biochar, and the porous nature of the biochar was used to adsorb the bacterial solution. The mixture was then air-dried at 20°C. Urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers were added, followed by aminated attapulgite. The mixture was then placed in a mixer and stirred thoroughly for 20 minutes to obtain a dry powder. The functional bacterial agent was selected from Bacillus subtilis and Bacillus amyloliquefaciens. The mass ratio of urea, monoammonium phosphate and potassium sulfate was 2:1:1. The amount of biochar added was 25%, the amount of functional bacterial agent added was 20%, the amount of aminated attapulgite added was 10%, and the amount of nitrogen-doped carbon nanofibers added was 1%.
[0030] (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0031] Example 3 A method for preparing a biochar-based slow-release fertilizer synergistic formulation for apples includes the following steps: (1) Polyacrylonitrile was used as a carbon source precursor and dissolved in dimethylformamide solvent. Urea or melamine was added as a nitrogen source. The mixture was spun into a nanofiber membrane using an electrospinning machine. Pre-oxidation and carbonization were carried out to obtain nitrogen-doped carbon nanofibers. The mass ratio of carbon source precursor to nitrogen source was 9:2. The pre-oxidation and carbonization conditions were: first, pre-oxidation and stabilization were carried out at 260℃ in an air atmosphere, and then carbonization was carried out at 950℃ for 3h under nitrogen protection. The nitrogen content in the nitrogen-doped carbon nanofibers was 7%.
[0032] (2) The natural attapulgite ore was crushed and calcined at 350°C for 2 hours. The thermally activated attapulgite was dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added. The mixture was stirred at 60°C for 6 hours to obtain aminated attapulgite. The amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added was 6%.
[0033] (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid; the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 3:1.
[0034] (4) The functional bacterial agent was mixed with biochar, and the porous nature of the biochar was used to adsorb the bacterial solution. The mixture was then air-dried at 25°C. Urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers were added, followed by aminated attapulgite. The mixture was then placed in a mixer and stirred thoroughly for 20 minutes to obtain a dry powder. The functional bacterial agent was selected from Bacillus subtilis and Bacillus amyloliquefaciens. The mass ratio of urea, monoammonium phosphate and potassium sulfate was 3:1:1. The amount of biochar added was 27%, the amount of functional bacterial agent added was 25%, the amount of aminated attapulgite added was 14%, and the amount of nitrogen-doped carbon nanofibers added was 3%.
[0035] (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0036] Example 4 A method for preparing a biochar-based slow-release fertilizer synergistic formulation for apples includes the following steps: (1) Polyacrylonitrile was used as a carbon source precursor and dissolved in dimethylformamide solvent. Urea or melamine was added as a nitrogen source. The mixture was spun into a nanofiber membrane using an electrospinning machine. Pre-oxidation and carbonization were performed to obtain nitrogen-doped carbon nanofibers. The mass ratio of carbon source precursor to nitrogen source was 10:1. The pre-oxidation and carbonization conditions were: first, pre-oxidation and stabilization were performed at 280℃ in an air atmosphere, and then carbonization was performed at 1000℃ for 2 hours under nitrogen protection. The nitrogen content in the nitrogen-doped carbon nanofibers was 9%.
[0037] (2) The natural attapulgite ore was crushed and calcined at 380°C for 3 hours. The thermally activated attapulgite was dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added. The mixture was stirred and reacted at 80°C for 6 hours to obtain aminated attapulgite. The amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added was 7%.
[0038] (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid; the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 5:2.
[0039] (4) The functional bacterial agent was mixed with biochar, and the porous nature of the biochar was used to adsorb the bacterial solution. The mixture was then air-dried at 30°C. Urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers were added, followed by aminated attapulgite. The mixture was then placed in a mixer and stirred thoroughly for 30 minutes to obtain a dry powder. The functional bacterial agent was selected from Bacillus subtilis and Bacillus amyloliquefaciens. The mass ratio of urea, monoammonium phosphate and potassium sulfate was 3:1:2. The amount of biochar added was 40%, the amount of functional bacterial agent added was 28%, the amount of aminated attapulgite added was 15%, and the amount of nitrogen-doped carbon nanofibers added was 1%.
[0040] (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0041] Example 5 A method for preparing a biochar-based slow-release fertilizer synergistic formulation for apples includes the following steps: (1) Polyacrylonitrile was used as a carbon source precursor and dissolved in dimethylformamide solvent. Urea or melamine was added as a nitrogen source. The mixture was spun into a nanofiber membrane using an electrospinning machine. Pre-oxidation and carbonization were performed to obtain nitrogen-doped carbon nanofibers. The mass ratio of carbon source precursor to nitrogen source was 11:2. The pre-oxidation and carbonization conditions were: first, pre-oxidation and stabilization were performed at 300℃ in an air atmosphere, and then carbonization was performed at 1050℃ for 3h under nitrogen protection. The nitrogen content in the nitrogen-doped carbon nanofibers was 10%.
[0042] (2) The natural attapulgite ore was crushed and calcined at 400℃ for 3h. The thermally activated attapulgite was dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added. The mixture was stirred and reacted at 80℃ for 7h to obtain aminated attapulgite. The amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added was 8%.
[0043] (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide coat the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid; the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 5:3.
[0044] (4) The functional bacterial agent was mixed with biochar, and the porous nature of the biochar was used to adsorb the bacterial solution. The mixture was then air-dried at 30°C. Urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers were added, followed by aminated attapulgite. The mixture was then placed in a mixer and stirred thoroughly for 30 minutes to obtain a dry powder. The functional bacterial agent was selected from Bacillus subtilis and Bacillus amyloliquefaciens. The mass ratio of urea, monoammonium phosphate and potassium sulfate was 3:1:2. The amount of biochar added was 45%, the amount of functional bacterial agent added was 32%, the amount of aminated attapulgite added was 18%, and the amount of nitrogen-doped carbon nanofibers added was 4%.
[0045] (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
[0046] Comparative Example 1 The difference from Example 1 is that nitrogen-doped carbon nanofibers were not added.
[0047] Comparative Example 2 The difference from Example 1 is that no amination attapulgite was added.
[0048] Comparative Example 3 The difference from Example 1 is that no modified γ-polyglutamic acid was added.
[0049] Table 1 Performance Test Results As shown in Table 1, the slow-release synergistic formulation of apple water and fertilizer based on biochar carrier prepared in Example 1 has excellent performance, indicating that the formulation contains macro-elements such as nitrogen, phosphorus, and potassium, as well as micro-elements introduced through modification, which meet the needs of apple trees throughout their entire growth period.
[0050] The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a biochar-based slow-release synergistic formulation for apples, characterized in that, Includes the following steps: (1) Polyacrylonitrile is used as a carbon source precursor, dissolved in dimethylformamide solvent, and urea or melamine is added as a nitrogen source. The mixture is spun into a nanofiber membrane using an electrospinning machine, and then pre-oxidized and carbonized to obtain nitrogen-doped carbon nanofibers. (2) The natural attapulgite ore is crushed and calcined at 300-400℃ for 2-3 hours. The thermally activated attapulgite is dispersed in an ethanol solution, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is added. The mixture is stirred and reacted at 60-80℃ for 6-7 hours to obtain aminated attapulgite. (3) Dissolve γ-polyglutamic acid in water, add acetic anhydride under alkaline conditions, dissolve chitosan oligosaccharide in dilute acetic acid, add it to the treated γ-polyglutamic acid, and use electrostatic self-assembly technology to make chitosan oligosaccharide wrap the surface of γ-polyglutamic acid chain to obtain modified γ-polyglutamic acid. (4) Mix the functional bacterial agent with biochar, and use the porous nature of biochar to adsorb the bacterial solution. Dry it in the shade at 20-30℃, add urea, monoammonium phosphate, potassium sulfate and nitrogen-doped carbon nanofibers, then add aminated attapulgite, put it into a mixer and stir thoroughly for 20-30 minutes to obtain dry powder material. (5) Dissolve the modified γ-polyglutamic acid in water to obtain a γ-polyglutamic acid solution, and spray the γ-polyglutamic acid solution evenly onto the dry powder material; make granules, dry them below 60°C, and sieve them to obtain an apple water-fertilizer slow-release synergistic preparation based on biochar carrier.
2. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (1), the mass ratio of the carbon source precursor to the nitrogen source is 7~11:1~2.
3. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (1), the pre-oxidation and carbonization conditions are as follows: first, pre-oxidation and stabilization are carried out at 250-300℃ in an air atmosphere, and then carbonization is carried out at 950-1050℃ for 2-3 hours under nitrogen protection; the nitrogen content in the nitrogen-doped carbon nanofibers is 5-10%.
4. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (2), the amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane added is 5-8%.
5. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (3), the mass ratio of γ-polyglutamic acid to chitosan oligosaccharide is 2-5:1-3.
6. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (4), the functional microbial agent is selected from at least one of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus megaterium, and Trichoderma harzianum.
7. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (4), the mass ratio of urea, monoammonium phosphate and potassium sulfate is 2-3:1:1-2; the amount of biochar added is 25-45%; and the amount of functional microbial agent added is 20-32%.
8. The preparation method of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 1, characterized in that, In step (4), the amount of aminated attapulgite added is 10-18%; the amount of nitrogen-doped carbon nanofibers added is 1-4%.
9. A biochar-based slow-release synergistic formulation for apples prepared by the method of preparing the biochar-based slow-release synergistic formulation for apples as described in any one of claims 1 to 8.
10. The apple water-fertilizer slow-release synergistic formulation based on biochar carrier according to claim 9, characterized in that, The particle size of the apple water-fertilizer slow-release synergistic formulation based on biochar carrier is 2-6 mm.