Capsule-type fertilizer and preparation method therefor

Abstract

The present application provides a capsule-type fertilizer and a preparation method therefor. The capsule-type fertilizer comprises a sealed hollow capsule body. The hollow capsule body comprises a capsule shell and a capsule shell cap connected to the capsule shell. The capsule shell comprises an inner shell and an outer shell. The composition of the outer shell comprises chitosan and β-glucose, and the composition of the inner shell comprises biochar and a binder. The composition of the capsule shell cap comprises a biological skeleton material, an antioxidant, and a binder. The interior of the capsule shell comprises core material A far away from the outer shell, the interior of the capsule shell cap comprises core material B, and the core material A and the core material B are isolated by a degradable separator. The composition of the core material A comprises a nitrogen fertilizer, and the composition of the core material B comprises a hydrogen-release plant growth agent precursor, a drying agent, and a flame retardant. The capsule-type fertilizer can achieve enhanced slow-release property of the fertilizer, delayed nutrient release rate, and slowed rate of the effectiveness reduction of the fertilizer, and promotes the growth and yield of crops.

Description

A capsule-type fertilizer and its preparation method

[0001] This application claims priority to Chinese Patent Application No. 202410688507.4, filed on May 29, 2024, entitled "A Capsule-type Fertilizer and a Preparation Method thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of fertilizers, and more specifically, to a capsule-type fertilizer and a method for its preparation. Background Technology

[0003] Slow-release fertilizers, also known as slow-efficiency fertilizers, are a new type of fertilizer that has been improved and upgraded based on traditional fertilizers. "Slow-release" means that the release rate of fertilizer nutrients is much lower than that of ordinary fast-dissolving fertilizers. These fertilizers can be applied in one application, reducing the loss of nutrients in the fertilizer, with a long fertilizer effect, improving fertilizer efficiency, and reducing the pollution of soil by fertilizer residues.

[0004] Slow-release capsule fertilizers are a new type of advanced slow-release fertilizer developed in recent years. Compared with ordinary slow-release fertilizers, the nutrients in slow-release capsule fertilizers are protected by the outer shell as the core material, making them less prone to volatilization and deterioration. Furthermore, the nutrient release rate and process are controllable, resulting in higher nutrient utilization and reduced nutrient loss due to leaching. However, current slow-release capsule fertilizers have the following drawbacks in storage, transportation, and application: the outer shell or core material of the capsule fertilizer is easily oxidized or decomposed by microorganisms due to water absorption and irradiation, leading to a decrease in fertilizer effectiveness; the outer shell of existing capsule fertilizers is mainly made of easily degradable materials, and even after the outer shell dissolves or decomposes in the soil, the nutrient release rate remains too fast, making it difficult to meet the required slow-release effect.

[0005] Application content

[0006] In view of this, this application provides a capsule-type fertilizer that can increase the slow-release properties of the fertilizer and slow down the nutrient release rate. At the same time, it can avoid the problem of fertilizer effectiveness reduction caused by water absorption, irradiation, material mixing, etc. in the storage, transportation, and application stages. In addition, it can also promote crop growth and increase yield.

[0007] This application also provides a method for preparing a capsule-type fertilizer, which can produce the above-mentioned capsule-type fertilizer and has a simple process.

[0008] In a first aspect, this application provides a capsule-type fertilizer, comprising a sealed hollow capsule body; the hollow capsule body includes a capsule shell and a capsule cap connected to the capsule shell, the capsule shell including an inner shell and an outer shell, wherein the outer shell is composed of chitosan and β-glucan, and the inner shell is composed of biochar and a binder; the capsule cap is composed of a bio-scaffold material, an antioxidant, and a binder; the capsule shell includes a core material A in its interior away from the outer shell, and the capsule cap includes a core material B in its interior, the core material A and the core material B being separated by a biodegradable membrane; the core material A is composed of nitrogen fertilizer, and the core material B is composed of a hydrogen-releasing plant growth promoter precursor, a desiccant, and a flame retardant.

[0009] In one optional embodiment, the hydrogen-releasing plant growth promoter precursor is at least one of magnesium, calcium, magnesium hydride, and calcium hydride.

[0010] In one optional embodiment, the bio-skeleton material is at least one of straw powder, rice husk powder, sawdust powder, rice straw powder, and bamboo shavings.

[0011] In one optional embodiment, the mass ratio of core material A to core material B is 70-95:5-30.

[0012] In one optional embodiment, the outer shell comprises, by weight, 40-50 parts chitosan, 40-50 parts β-glucan, and 0-20 parts binder;

[0013] And / or, by mass parts, the inner shell comprises 80-95 parts biochar and 5-20 parts binder;

[0014] And / or, by weight, the capsule shell comprises 75-94 parts of bioscaffold material, 1-5 parts of antioxidant, and 5-20 parts of binder.

[0015] In one optional embodiment, the core material A comprises, by weight, 20-100 parts nitrogen fertilizer, 0-40 parts phosphate fertilizer, and 0-40 parts potassium fertilizer compound; the core material B comprises 70-94 parts hydrogen-releasing plant growth promoter precursor, 1-10 parts desiccant, and 5-20 parts flame retardant.

[0016] In an alternative embodiment, the capsule shell also includes pigments as a component.

[0017] In one optional embodiment, the hollow capsule has a length of 1mm-100mm, a diameter of 0.4mm-45mm, and a thickness of 0.1mm-2.0mm.

[0018] In one alternative embodiment, the total volume of core material A and core material B accounts for 70%-100% of the internal volume of the capsule.

[0019] Secondly, this application provides a method for preparing the above-mentioned capsule-type fertilizer, comprising the following steps:

[0020] 1) Prepare core material A, which includes a compound of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer, and core material B, which includes a precursor of hydrogen-releasing plant growth agent, desiccant, and flame retardant.

[0021] 2) Add chitosan and β-glucose to the solution containing emulsifier, stir, add thickener and binder, continue stirring, and continuously purge nitrogen gas during the process to remove air and bubbles inside and on the surface of the system. Let the resulting mixture stand for 30-60 minutes, then press it into a thin layer using a film press to prepare a single-layer capsule shell.

[0022] 3) A paste containing biochar powder and binder is applied to one surface of the single-layer capsule shell, and after drying, a capsule shell is obtained;

[0023] 4) A mixture containing bio-scaffold materials, antioxidants, and binders is pressed into a thin layer using a film press to obtain a capsule shell cap;

[0024] 5) Fill the capsule shell with core material A and fill the capsule cap with core material B. Place a biodegradable diaphragm between core material A and core material B. The diaphragm is completely attached to the edge of the capsule shell and the edge of the capsule cap. Then connect the capsule cap to the capsule shell to completely seal the capsule shell and the capsule cap, thus obtaining the capsule fertilizer.

[0025] In an optional embodiment, step 4) further includes the following process: placing the capsule shell cap into a pigment solution or pigment suspension with a mass fraction of 1%-10%, stirring for 30-60 minutes, and then drying.

[0026] The capsule-type fertilizer provided in this application can increase the slow-release properties of fertilizer and slow down the nutrient release rate. At the same time, it can avoid the problem of fertilizer effectiveness reduction caused by water absorption, irradiation, and material mixing in the outer shell or core material during storage and transportation. In addition, it can promote crop growth and increase yield. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0028] Figure 1 shows a capsule-type fertilizer according to a specific embodiment of this application;

[0029] In the diagram, 001: capsule cap, 002: capsule shell, 003: biodegradable diaphragm;

[0030] Figure 2 is a process flow diagram of the preparation of a capsule-type fertilizer according to a specific embodiment of this application.

[0031] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In the accompanying drawings of the embodiments of this application, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, the terms describing positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] In a first aspect, this application provides a capsule-type fertilizer, comprising, as shown in FIG1, a sealed hollow capsule body; the hollow capsule body includes a capsule shell 002 and a capsule cap 001 connected to the capsule shell, the capsule shell including an inner shell and an outer shell, wherein the outer shell is composed of chitosan and β-glucan, and the inner shell is composed of biochar and a binder; the capsule cap is composed of a bio-scaffold material, an antioxidant, and a binder; the capsule shell includes a core material A in the interior away from the outer shell, and the capsule cap includes a core material B in the interior, the core material A and the core material B being separated by a biodegradable membrane 003;

[0036] The core material A is composed of nitrogen fertilizer, and the core material B is composed of hydrogen-releasing plant growth promoter precursor, desiccant, and flame retardant.

[0037] The main reason why the capsule fertilizer of this application can increase the slow-release properties of fertilizer, delay the nutrient release rate, and promote crop growth and development is that: after the capsule fertilizer is applied to the soil, as irrigation water enters the capsule fertilizer, the hydrogen-releasing plant growth promoter precursor in the core material B reacts chemically with water to generate hydrogen gas. The reaction equation includes at least one of the following: ①Mg+2H2O=Mg(OH)2+H2↑ ②Ca+2H2O=Ca(OH)2+H2↑ ③MgH2+2H2O=Mg(OH)2+2H2↑ ④CaH2+2H2O=Ca(OH)2+2H2↑;

[0038] Hydrogen is an important element for plant growth, and its release creates a porous structure on the capsule shell, providing more channels for irrigation water to enter the hollow capsule. The existing porous structure of the capsule shell also facilitates the decomposition of biomass materials such as bioscaffold materials, chitosan, and β-glucose. Furthermore, because hydrogen's density is much lower than that of air, soil, and water, the generated hydrogen is released upwards, resulting in porous structures primarily located in the capsule shell. This also prevents nutrients from migrating from the capsule shell into the soil layer and thus avoiding loss. When the nitrogen, phosphorus, and potassium fertilizer complex in core material A dissolves in water and migrates to the capsule shell, it is fixed to components such as biochar, bioscaffold materials, chitosan, and β-glucose through adsorption, electrostatics, and complexation, preventing rapid nutrient loss and effectively improving nutrient utilization. In addition, due to the protective effect of the capsule shell on core material A, the entry of irrigation water into the capsule shell is a relatively slow process. Therefore, the migration of nutrients from core material A to the outside of the capsule shell is a long-term process, greatly enhancing nutrient fixation and slowing down the nutrient release rate.

[0039] The main reason why the capsule-type fertilizer of this application can delay the deactivation of the active ingredients is that: the multi-layer structure of the capsule shell and each component provide good protection for the core material A, avoiding the deactivation of the core material A due to water absorption, irradiation, oxidation, and decomposition by microorganisms during storage and transportation; the biodegradable membrane isolates the core material A and the core material B, avoiding the decline in fertilizer effectiveness and function due to the mixing of capsule core materials during storage, transportation, and application.

[0040] Furthermore, due to its structural composition and the Mg(OH)2 and Ca(OH)2 produced after application, the capsule fertilizer of this application can react with carbon dioxide in the soil to generate MgCO3 and CaCO3. While reducing carbon dioxide emissions, it can also serve as a nutrient element required for plant growth and development. When the bio-scaffold material, chitosan, and β-glucan in the capsule fertilizer decompose naturally in the soil, they can replenish soil organic matter. Biochar can enhance soil microbial richness, promote soil organic matter synthesis, improve soil properties, inhibit soil acidification, and reduce soil greenhouse gas emissions.

[0041] The aforementioned β-glucose is also known as BETA-glucose, with the English name BETA-D-GLUCOSE and the molecular formula C6H2O. 12 O6 can be purchased commercially or prepared using existing methods; this invention does not impose any particular limitation on it.

[0042] It is understood that the main function of a biodegradable membrane is to prevent solids from passing through it. For example, the aforementioned biodegradable membrane is one of cellulose membrane, lignin membrane, hemicellulose membrane, chitosan membrane, starch membrane, or biomass-based composite membrane.

[0043] For example, the interior of the inner shell of the capsule shell includes a core material A.

[0044] For example, the capsule cap is connected to the capsule body by a sleeve, and the diameter of the capsule cap is slightly larger than that of the capsule body, so that the capsule cap and the capsule body can be completely sealed and fitted.

[0045] For example, the binder is at least one of gelatin, carrageenan, sodium carboxymethyl cellulose, konjac gum, agar, and pectin.

[0046] In one optional embodiment, the hydrogen-releasing plant growth promoter precursor is at least one of magnesium, calcium, magnesium hydride, and calcium hydride.

[0047] In one optional embodiment, the bio-skeleton material is at least one of straw powder, rice husk powder, sawdust powder, rice straw powder, and bamboo shavings.

[0048] In one optional embodiment, the mass ratio of core material A to core material B is 70-95:5-30.

[0049] In one alternative embodiment, the outer shell comprises, by weight, 40-50 parts chitosan, 40-50 parts β-glucan, and 0-20 parts binder;

[0050] The outer shell contains chitosan and β-glucose, which play a functional role. After the chitosan and β-glucose are degraded, the exposed channels allow water to enter the capsule. The nitrogen, phosphorus, and potassium nutrients in the core material are absorbed by the plant through the channels. At the same time, the hydrogen-releasing plant growth promoter precursor can also release hydrogen gas. In addition, the chitosan and β-glucose also have a fixing effect on nitrogen, phosphorus, and potassium nutrients. Since the degradation rate, intensity, and molecular weight of chitosan and β-glucose are different, the above-mentioned implementation method within the above ratio range can make the outer shell have a controllable degradation rate, suitable mechanical strength, toughness, and density, which helps to improve the slow-release performance and help the soil replenish organic matter.

[0051] And / or, the inner shell is composed of 80-95 parts biochar and 5-20 parts binder;

[0052] In this system, the inner shell is made of biochar, which functions as a binder. The biochar is bonded together with each other and then adheres to the outer shell. It also fixes and slowly releases nitrogen, phosphorus, and potassium nutrients. The implementation within the above-mentioned proportion range allows the inner shell to have good function, suitable mechanical strength and toughness. At the same time, it has a good fixation and slow release effect on nitrogen, phosphorus, and potassium nutrients. Furthermore, the appropriate biochar content can promote the improvement of soil carbon sequestration capacity, regulate soil ecology and microbial community, thus improving slow release performance and soil improvement. If the binder ratio is too high, the inner shell will lose its original structure, mechanical strength and function. If the binder ratio is too low, the inner shell will not be able to be formed and will not be able to adhere to the outer shell.

[0053] And / or, the capsule shell is composed of 75-94 parts of bioscaffold material, 1-5 parts of antioxidant, and 5-20 parts of binder.

[0054] Among them, the bio-scaffold material plays a functional role in the capsule shell and cap. The bio-scaffold material maintains the mechanical strength of the capsule shell and cap and the capsule as a whole, and has a certain degree of toughness, flexibility and extensibility. It also has a certain slow-release effect. Antioxidants protect the core material from oxidation and prevent the fertilizer effectiveness from decreasing due to oxidation. The implementation method within the above proportion range can effectively improve the slow-release performance, replenish soil organic matter, and protect the core material. If the proportion of bio-scaffold material is too low, it will result in poor strength, toughness, flexibility and extensibility of the material. If the proportion of antioxidant is too high, it will affect the structure, function and strength of the capsule shell and cap. If the proportion of binder is too high, the capsule shell and cap will lose its original structure, mechanical strength and function. If the proportion of binder is too low, the capsule shell and cap will not be able to be formed.

[0055] For example, the above-mentioned biological skeleton material is one or more of straw powder, rice husk powder, sawdust powder, rice straw powder, and bamboo shavings.

[0056] For example, the antioxidant mentioned above is one or more of ascorbic acid, isoascorbic acid, phytic acid, and tea polyphenols.

[0057] In one optional embodiment, by weight, the core material A comprises 20-100 parts nitrogen fertilizer, 0-40 parts phosphate fertilizer, and 0-40 parts potassium fertilizer compound; the core material B comprises 70-94 parts hydrogen-releasing plant growth promoter precursor, 1-10 parts desiccant, and 5-20 parts flame retardant.

[0058] This ratio ensures that the fertilizer has a high nitrogen, phosphorus, and potassium content, produces an appropriate amount of hydrogen, and has a reasonable ratio of nitrogen, phosphorus, potassium, calcium, magnesium, and hydrogen. This helps promote crop growth, maintain yield, and improve quality. The desiccant prevents the core material from deteriorating and losing its effectiveness due to moisture absorption during storage and transportation, while the flame retardant prevents the core material from burning during storage and transportation. However, an excessively high ratio of desiccant and flame retardant can lead to a decrease in the fertilizer's fertility and function.

[0059] For example, the nitrogen fertilizer of this application is one or more of urea, ammonium sulfate, ammonium bicarbonate, sodium nitrate, calcium nitrate, ammonium nitrate, and calcium ammonium nitrate; the phosphate fertilizer is one or more of monoammonium phosphate, diammonium phosphate, superphosphate, triple superphosphate, calcium magnesium phosphate, and phosphate rock powder; the potassium fertilizer is one or more of potassium sulfate, potassium nitrate, potassium dihydrogen phosphate, and potassium carbonate; the desiccant is one or more of calcium chloride, silica gel, and lime; and the flame retardant is one or more of magnesium hydroxide, calcium hydroxide, calcium borate, magnesium borate, and sodium borate.

[0060] In an alternative embodiment, the capsule shell also includes pigments as a component.

[0061] For example, the above-mentioned pigments are one or more of the following: carotene, beetroot red, curcumin, safflower yellow, shellac red, blueberry red, capsicum red, capsicum orange, red rice red, chrysanthemum yellow extract, black bean red, sorghum red, corn yellow, radish red, red yeast rice red, Malabar spinach red, blackcurrant red, gardenia yellow, gardenia blue, sea buckthorn yellow, hibiscus red, mulberry red, natural mustard red, grape skin red, buddleja yellow, alkanet root red, tea yellow pigment, tea green pigment, citrus yellow, sodium copper chlorophyll, phycocyanin, titanium dioxide, carmine, amaranth, sunset yellow, erythrosine, lemon yellow, new red, indigo, brilliant blue.

[0062] In one optional embodiment, the hollow capsule has a length of 1mm-100mm, a diameter of 0.4mm-45mm, and a thickness of 0.1mm-2.0mm.

[0063] In one alternative embodiment, the total volume of core material A and core material B accounts for 70%-100% of the internal volume of the capsule.

[0064] Secondly, this application provides a method for preparing the above-mentioned capsule-type fertilizer, the process flow of which is shown in Figure 2, where 01 to 05 correspond to steps 1) to 5), respectively. Specifically, the preparation method includes the following steps:

[0065] 1) Prepare core material A, which includes a compound of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer, and core material B, which includes a precursor of hydrogen-releasing plant growth agent, desiccant, and flame retardant.

[0066] 2) Add chitosan and β-glucose to the solution containing emulsifier, stir, add thickener and binder, continue stirring, and continuously purge nitrogen gas during the process to remove air and bubbles inside and on the surface of the system. Let the resulting mixture stand for 30-60 minutes, then press it into a thin layer using a film press to prepare a single-layer capsule shell.

[0067] 3) A paste containing biochar powder and binder is applied to one surface of the single-layer capsule shell, and after drying, a capsule shell is obtained;

[0068] 4) A mixture containing bio-scaffold materials, antioxidants, and binders is pressed into a thin layer using a film press to obtain a capsule shell cap;

[0069] 5) Fill the capsule shell with core material A and fill the capsule cap with core material B. Place a biodegradable diaphragm between core material A and core material B. The diaphragm is completely attached to the edge of the capsule shell and the edge of the capsule cap. Then connect the capsule cap to the capsule shell to completely seal the capsule shell and the capsule cap, thus obtaining the capsule fertilizer.

[0070] It is understood that the thickness of the thin layer involved in steps 2) and 4) can be adjusted by the technician as needed. For example, by adjusting the thin layer, the thickness of the capsule shell and capsule cap can be in the range of 0.1mm-2.0mm.

[0071] In an optional embodiment, step 4) further includes the following process: placing the capsule shell cap into a pigment solution or pigment suspension with a mass fraction of 1%-10%, stirring for 30-60 minutes, and then drying.

[0072] For example, the thickener is sodium alginate or potassium alginate; the emulsifier is potassium metaphosphate or sodium metaphosphate.

[0073] For example, biomass materials are carbonized at 300℃-900℃ for 30min-720min, wherein the heating rate is 0.5℃ / min-50℃ / min, the carbonization atmosphere is argon, nitrogen or vacuum, and the solid particles are pulverized after cooling to obtain biochar powder.

[0074] For example, the above-mentioned biomass materials can be selected from at least one of straw, rice husks, livestock and poultry manure, cyanobacteria, sugar residue, distiller's grains, fungal residue, traditional Chinese medicine residue, sludge, starch, chitosan, etc.

[0075] The present application is described in detail below with reference to specific embodiments:

[0076] The chitosan used in the following tests was purchased from Shanghai Aladdin Reagent Co., Ltd., with the following specifications: degree of deacetylation ≥95%, viscosity 100-200 mPa·s, CAS No.: 9012-76-4;

[0077] Gelatin CAS No.: 9000-70-8, Sodium Alginate CAS No.: 9005-38-3;

[0078] β-glucose was purchased from Shanghai Aladdin Reagent Co., Ltd., with the following specifications: purity greater than 80%, molecular weight: 180.15, CAS number: 28905-12-6.

[0079] Example 1

[0080] A capsule-type fertilizer is provided, comprising a sealed hollow capsule body; the hollow capsule body includes a capsule shell and a capsule cap connected to the capsule shell, the capsule shell including an inner shell and an outer shell, wherein the outer shell is composed of chitosan, β-glucan, and gelatin, and the inner shell is composed of biochar and gelatin; the capsule cap is composed of a bio-scaffold material, ascorbic acid, and gelatin; the capsule shell includes a core material A inside away from the outer shell, and the capsule cap includes a core material B inside, the core material A and the core material B being separated by a biodegradable membrane; the core material A is composed of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer, and the core material B is composed of magnesium, a precursor of hydrogen-releasing plant growth promoter, calcium chloride, a desiccant, and magnesium hydroxide, a flame retardant.

[0081] Its preparation method includes the following steps:

[0082] 1) Weigh out the raw materials required for preparing the capsule fertilizer according to the specified mass ratio;

[0083] 2) Mix 50 parts nitrogen fertilizer, 25 parts phosphorus fertilizer, and 25 parts potassium fertilizer evenly to obtain core material A; mix 85 parts magnesium, 5 parts calcium chloride, and 10 parts magnesium hydroxide evenly to obtain core material B;

[0084] 3) Add the emulsifier to deionized water and stir for 30 minutes under heating conditions of 40-80℃ to prepare a solution with a mass fraction of 50%. Then add 45 parts of chitosan and 45 parts of β-glucose in sequence, stir for 20 minutes, add 0.5 parts of sodium alginate, and continue stirring for 30 minutes. Then add 10 parts of gelatin and stir for 30 minutes. During this period, nitrogen gas is continuously introduced to remove air and bubbles inside and on the surface of the mixture. After standing for 60 minutes, press it into a thin layer using a film press to obtain a single-layer capsule shell with a thickness of 0.4 mm and a height of 20 mm.

[0085] 4) Carbonize the straw at 500℃ for 120 min, with a heating rate of 20℃ / min and a nitrogen atmosphere. After cooling, crush the solid particles to obtain biochar powder. Then, add 90 parts of biochar powder and 10 parts of gelatin to 25 parts of deionized water and stir for 30 min to obtain biochar slurry. Then, evenly coat the biochar slurry onto the surface of the single-layer capsule shell. After drying, obtain a double-layer capsule shell with a thickness of 0.8 mm and a height of 20 mm.

[0086] 5) Add 87 parts straw powder, 3 parts ascorbic acid, and 10 parts gelatin to 25 parts deionized water. Stir the mixture for 30 minutes, continuously purging with nitrogen to remove air and bubbles from the interior and surface of the mixture. Let it stand for 60 minutes, then press it into a thin layer using a film press to obtain undyed capsule shells. Add curcumin to deionized water and stir at 80°C for 30 minutes to prepare a 5% curcumin solution suspension. Then add the undyed capsule shells to a pigment solution or pigment suspension. Stir the solution or suspension for 60 minutes, remove the shells, and dry them to obtain capsule shells with a thickness of 0.4 mm and a height of 20 mm.

[0087] 6) Fill the capsule shell with core material A, and then fill the capsule cap with core material B. The mass ratio of core material A to core material B is 80:20. Then, place a cellulose diaphragm at the other end of the capsule cap where core material B is placed. The diaphragm is perpendicular to the upper and lower walls of the capsule cap and is completely attached to the upper and lower walls. Then, put the capsule cap on the outside of the capsule shell and press the capsule shell with a press to completely seal the capsule shell and the capsule cap, so as to obtain the finished capsule fertilizer with a thickness of 1.2 mm, a length of 30 mm and a diameter of 10 mm.

[0088] Example 2

[0089] This is basically the same as Example 1, except that the precursor of the hydrogen-releasing plant growth agent used in this example is calcium hydride.

[0090] Example 3

[0091] The method is basically the same as in Example 1, except that in step 2), the amounts of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer are 20 parts, 0 parts, and 0 parts, respectively; the amounts of magnesium, calcium chloride, and magnesium hydroxide are 75 parts, 1 part, and 5 parts, respectively; in step 3), the amounts of chitosan, β-glucose, and gelatin are 40 parts, 40 parts, and 0 parts, respectively; in step 4), the carbonization temperature is 300℃, the carbonization time is 30 min, the heating rate is 0.5℃ / min, and the amounts of biochar powder, gelatin, and deionized water are 80 parts, 5 parts, and 20 parts, respectively; in step 5), the amounts of straw powder, ascorbic acid, gelatin, and deionized water are 75 parts, 1 part, 5 parts, and 20 parts, respectively, and the mass fraction of curcumin suspension is 1%; in step 6), the mass ratio of core material A to core material B is 70:30, and the thickness of the finished capsule fertilizer is 0.1 mm, the length is 1 mm, and the diameter is 0.4 mm.

[0092] Example 4

[0093] The method is basically the same as in Example 1, except that in step 2), the amounts of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer are 100 parts, 40 parts, and 40 parts, respectively, and the amounts of magnesium, calcium chloride, and magnesium hydroxide are 94 parts, 10 parts, and 20 parts, respectively; in step 3), the amounts of chitosan, β-glucose, and gelatin are 50 parts, 50 parts, and 20 parts, respectively; in step 4), the carbonization temperature is 900℃, the carbonization time is 720 min, the heating rate is 50℃ / min, and the amounts of biochar powder, gelatin, and deionized water are 95 parts, 20 parts, and 50 parts, respectively; in step 5), the amounts of straw powder, ascorbic acid, gelatin, and deionized water are 94 parts, 5 parts, 20 parts, and 50 parts, respectively, and the mass fraction of curcumin suspension is 10%; in step 6), the mass ratio of core material A to core material B is 95:5, and the finished capsule-shaped fertilizer has a thickness of 2 mm, a length of 100 mm, and a diameter of 45 mm.

[0094] Example 5

[0095] This is basically the same as Example 1, except that the biological skeleton material used in this example is wood powder.

[0096] Comparative Example 1

[0097] This is basically the same as Example 1, except that a cellulose membrane is not used in this example.

[0098] Comparative Example 2

[0099] This embodiment is basically the same as Example 1, except that step 4) is not performed. That is, the capsule shell of this embodiment is a single layer and does not contain a biochar layer.

[0100] Comparative Example 3

[0101] This is basically the same as Example 1, except that this example does not use hydrogen-releasing plant growth promoter precursors.

[0102] Comparative Example 4

[0103] This is basically the same as Example 1, except that the outer capsule shell of this example is composed of 90 parts chitosan and 10 parts binder.

[0104] Test case

[0105] All the above embodiments were tested for slow-release effect, fertilizer effectiveness, and crop growth. The test methods are as follows:

[0106] (1) Slow-release effect: The nutrient release rate of the capsule fertilizer was tested using the soil column leaching method. The specific steps were as follows: a PVC pipe was selected as the leaching device, and the bottom of the PVC pipe was sealed with a 200-mesh nylon mesh. The capsule fertilizer (2g) in all the above examples and comparative examples was mixed with soil (100g) to obtain a soil-fertilizer mixture sample. In addition, nitrogen, phosphorus and potassium compound fertilizer was mixed with soil as a blank group. Then, 10g of quartz sand, 100g of soil-fertilizer mixture sample and 10g of quartz sand were laid in the PVC pipe from bottom to top. Deionized water was then added to the soil column and allowed to stand for 24 hours to allow the soil moisture content to reach saturation and be in a stable equilibrium state. Then, 30mL of deionized water was added to each soil column for leaching after 1, 3, 7 and 28 days. The leaching solution was collected at the bottom of the PVC pipe, and the nutrient release rate of the capsule fertilizer was calculated based on the nitrogen content in the leaching solution. The test results are listed in Table 1.

[0107] (2) Fertilizer effectiveness: Kraft paper was laid flat on the outdoor ground, and the edges and sides of the kraft paper were pressed down with heavy objects. Then, the capsule-type fertilizers from all the above examples and comparative examples were placed on the kraft paper, with a spacing of not less than 2 cm between each capsule. After being left to stand naturally for 30 days, the capsule-type fertilizers were mixed evenly with soil at a mass ratio of 1:50 and transferred to pots for soil cultivation. During this period, the soil moisture content was maintained at about 60%. In addition, a control group was set up without adding capsule-type fertilizers. After 28 days of cultivation, the soil bulk density, soil pH, and soil organic carbon content were tested. The test results are listed in Table 2.

[0108] (3) Crop growth: The capsule fertilizers from all the above examples and comparative examples were mixed evenly with the soil at a rate of 150 kg / ha. The mixed soil was then placed in pots, and deionized water was added to fully moisten the soil. A control group was also included, without the capsule fertilizer. Next, 8 seeds of pakchoi were sown in each pot, and 3 seedlings were transplanted into each pot after 5 days. The pakchoi was watered regularly. After 40 days of growth, the pakchoi was harvested, and the yield, root-to-shoot ratio, and harvest index of each pot were measured. The test results are listed in Table 2.

[0109] Table 1 Results of sustained-release effect test

[0110] As shown in Table 1, compared with the comparative example, the capsule-type slow-release fertilizers prepared in Examples 1-5 have a lower nutrient release rate and a better slow-release effect.

[0111] Table 2 Results of Fertilizer Effectiveness and Crop Growth Tests

[0112] As shown in Table 2, compared with the comparative example, the capsule-type slow-release fertilizers prepared in Examples 1-5, after being placed outdoors naturally for 30 days, have the advantages of improving acidic soil, increasing soil organic carbon, and reducing soil bulk density, showing good effectiveness. At the same time, the capsule-type slow-release fertilizers prepared in Examples 1, 2, and 5 increased the yield and harvest index of Chinese cabbage and reduced the root-to-shoot ratio, showing a good effect of promoting crop yield.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A capsule-type fertilizer, characterized in that, The invention includes a sealed hollow capsule body; the hollow capsule body includes a capsule shell and a capsule cap connected to the capsule shell, the capsule shell including an inner shell and an outer shell, wherein the outer shell is composed of chitosan and β-glucan, and the inner shell is composed of biochar and a binder; the capsule cap is composed of a bio-scaffold material, an antioxidant, and a binder; the capsule shell includes a core material A inside away from the outer shell, and the capsule cap includes a core material B inside, the core material A and the core material B being separated by a biodegradable membrane; the core material A is composed of nitrogen fertilizer, and the core material B is composed of a hydrogen-releasing plant growth promoter precursor, a desiccant, and a flame retardant.

2. The capsule-type fertilizer according to claim 1, characterized in that, The precursor of the hydrogen-releasing plant growth agent is at least one of magnesium, calcium, magnesium hydride, and calcium hydride.

3. The capsule-type fertilizer according to claim 1, characterized in that, The biological skeleton material is at least one of straw powder, rice husk powder, sawdust powder, rice straw powder, and bamboo shavings.

4. The capsule-type fertilizer according to claim 1, characterized in that, The mass ratio of core material A to core material B is 70-95:5-30.

5. The capsule-type fertilizer according to any one of claims 1-4, characterized in that, The outer shell comprises, by weight, 40-50 parts chitosan, 40-50 parts β-glucose, and 0-20 parts binder; And / or, by mass parts, the inner shell comprises 80-95 parts biochar and 5-20 parts binder; And / or, by weight, the capsule shell comprises 75-94 parts of bioscaffold material, 1-5 parts of antioxidant, and 5-20 parts of binder.

6. The capsule-type fertilizer according to any one of claims 1-4, characterized in that, By mass, the components of core material A include 20-100 parts nitrogen fertilizer, 0-40 parts phosphate fertilizer, and 0-40 parts potassium fertilizer compound; the components of core material B include 70-94 parts hydrogen-releasing plant growth promoter precursor, 1-10 parts desiccant, and 5-20 parts flame retardant.

7. The capsule-type fertilizer according to any one of claims 1-4, characterized in that, The capsule shell also includes pigments.

8. The capsule-type fertilizer according to any one of claims 1-4, characterized in that, The hollow capsule has a length of 1mm-100mm, a diameter of 0.4mm-45mm, and a thickness of 0.1mm-2.0mm. And / or, the total volume of core material A and core material B accounts for 70%-100% of the internal volume of the capsule.

9. A method for preparing the capsule-type fertilizer according to any one of claims 1-8, characterized in that, Includes the following steps: 1) Prepare core material A, which includes a compound of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer, and core material B, which includes a precursor of hydrogen-releasing plant growth agent, desiccant, and flame retardant. 2) Add chitosan and β-glucose to the solution containing emulsifier, stir, add thickener and binder, continue stirring, and continuously purge nitrogen gas during the process to remove air and bubbles inside and on the surface of the system. Let the resulting mixture stand for 30-60 minutes, then press it into a thin layer using a film press to prepare a single-layer capsule shell. 3) A paste containing biochar powder and binder is applied to one surface of the single-layer capsule shell, and after drying, a capsule shell is obtained; 4) A mixture containing bio-scaffold materials, antioxidants, and binders is pressed into a thin layer using a film press to obtain a capsule shell cap; 5) Fill the capsule shell with core material A and fill the capsule cap with core material B. Place a biodegradable diaphragm between core material A and core material B. The diaphragm is completely attached to the edge of the capsule shell and the edge of the capsule cap. Then connect the capsule cap to the capsule shell to completely seal the capsule shell and the capsule cap, thus obtaining the capsule fertilizer.

10. The preparation method according to claim 9, characterized in that, Step 4) also The process includes the following steps: placing the capsule shell into a pigment solution or pigment suspension with a mass fraction of 1%-10%, stirring for 30-60 minutes, and then drying.

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