Crushed particle slow controlled release organic fertilizer, and preparation method and application thereof

Abstract

This invention discloses a controlled-release organic fertilizer with crushed granules, comprising organic fertilizer core particles and a controllable degradable coating layer. The core particles have an irregular polyhedral structure and contain organic matter and nitrogen, phosphorus, and potassium nutrients. The coating layer consists of a hydrophobic inner layer and a hydrophilic outer layer containing an inorganic salt micropore-forming agent. Through the synergistic effect of physical barriers and micropore diffusion, the nutrient release rate is controllable. The preparation method includes: processing well-rotted raw materials into core particles using a specific process, and then sequentially spraying the inner and outer coating liquids onto the core particles via a fluidized bed. The double-layer coating structure of this invention provides a dual controlled-release barrier. The dense coating layer effectively blocks direct contact between high-concentration nutrients and seed or seedling roots in the early stages of fertilization, avoiding the seedling burn phenomenon common in traditional organic fertilizers. Furthermore, the nutrient release curve has a high degree of matching with crop requirements, allowing for one-time basal application without seedling burn, resulting in high fertilizer utilization. The production process is mature and suitable for large-scale promotion.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer technology, specifically to a crushed granule slow-release organic fertilizer, its preparation method, and its application. Background Technology

[0002] Organic fertilizer, as an important input in green agriculture, plays an irreplaceable role in improving soil, enhancing soil fertility, and promoting crop growth. However, traditional organic fertilizers have several significant drawbacks in practical applications: 1. The nutrient release rate is uncontrollable. Slow release in the early stage may lead to insufficient nutrition in the seedling stage, while rapid release in the later stage may not match the crop's fertilizer requirements and result in low utilization. 2. If it is not fully decomposed or the local concentration is too high, it is easy to cause "root burn" and "seedling burn", which is unsafe for seeds and seedlings; 3. The fertilizer effect is delayed, making it difficult to meet the immediate nutrient needs of crops during their critical growth period.

[0003] In the prior art, to solve the problem of nutrient release, a technology using polymer-coated fertilizers has emerged. For example, patent publication number CN118930386A describes a high-bio-based polyurethane-coated slow-release nitrogen fertilizer and its application in the fermentation production of straw organic fertilizer. The organic fertilizer in this patent includes a fertilizer core and a polyurethane coating material sprayed onto the surface of the fertilizer core, which enables the slow release of fertilizer.

[0004] However, the aforementioned patents only improve the coating material, and for fertilizer granules with a single chemical composition, the compatibility between the coating material and the surface of the organic fertilizer granules, the bonding strength, and the regulation effect on the release of complex organic components are all unsatisfactory.

[0005] In addition, conventional organic fertilizer granulation often pursues spherical shape, resulting in a relatively small specific surface area, which is not conducive to the uniform adhesion of coating materials and efficient controlled release.

[0006] Therefore, developing a new type of organic fertilizer that can retain the inherent advantages of organic fertilizer, achieve controlled slow release of nutrients, be safe to apply, and be suitable for industrial production has become an urgent technical problem to be solved in this field.

[0007] Based on this, the present invention designs a slow-release organic fertilizer made from crushed granules, its preparation method and application, in order to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a controlled-release organic fertilizer made from crushed granules, its preparation method and application. By designing specific granule morphology and composite coating structure, intelligent controlled release and efficient utilization of nutrients are achieved, while avoiding the risk of root burn, thus solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A controlled-release organic fertilizer made from crushed granules, its preparation method, and its application, including: The core particles of organic fertilizer are irregular polyhedral particles, including organic matter, nitrogen (N), phosphorus (P2O5), potassium (K2O) and trace elements. Among them, the irregular polyhedral particles have a larger specific surface area than spherical particles, which not only facilitates the adhesion of the coating liquid and forms a more uniform and firm film layer, but also increases the contact surface with the soil, which is conducive to the balanced release of nutrients. The controllable degradation coating layer consists of an inner coating layer and an outer coating layer. The double-layer coating structure provides a dual controlled-release barrier, wherein: The inner membrane layer is a first biodegradable polymer material layer with strong hydrophobicity and slow degradation rate. As the main control barrier, its slow biodegradation process determines the medium and long-term nutrient release rate, so that the release curve is better matched with the crop growth requirements. The outer coating layer is a second biodegradable polymer material layer with strong hydrophilicity and containing inorganic salt micropore forming agent. When the outer coating layer comes into contact with water, the inorganic salt micropore forming agent dissolves to form microchannels, resulting in slow release in the initial stage of activation.

[0010] The double-layer coating structure of this invention can increase fertilizer utilization by more than 30%. Furthermore, the dense coating layer effectively blocks the direct contact between high-concentration nutrients and seed or seedling roots in the early stage of fertilization, avoiding the seedling burn phenomenon commonly seen in traditional organic fertilizers, and making it possible to sow seeds and fertilizers simultaneously.

[0011] Furthermore, by mass percentage, the total nutrient content (N+P2O5+K2O) of nitrogen, phosphorus, and potassium in the core particles of organic fertilizer is 20%~50%, and the organic matter content is 25%~60%.

[0012] Furthermore, the raw materials for the core organic fertilizer particles include at least one of livestock and poultry manure, crop straw, kitchen waste, and mushroom residue, and are subjected to aerobic fermentation until fully decomposed.

[0013] Furthermore, the total mass of the controllable degradable coating layer accounts for 3% to 15% of the total mass of the organic fertilizer, the thickness of the inner coating layer is 10 to 50 μm, and the thickness of the outer coating layer is 20 to 100 μm.

[0014] Furthermore, the first biodegradable polymer material layer uses at least one of polylactic acid (PLA), polyhydroxyalkanoate (PHA), and polycaprolactone (PCL); the second biodegradable polymer material layer uses at least one of starch-based plastic, cellulose derivative, and polybutylene succinate (PBS); and the inorganic salt micropore forming agent uses at least one of sodium chloride, potassium sulfate, and ammonium phosphate, with a particle size of 10-50 μm, accounting for 5%-30% of the mass of the outer coating layer.

[0015] This invention also provides a method for preparing crushed granular slow-release organic fertilizer, which integrates standard fertilizer processing equipment, clarifies key process parameters, ensures product consistency and production repeatability, facilitates large-scale production, and includes the following steps: S1. Preparation of organic fertilizer core particles: After the decomposed organic raw materials are mixed and crushed, they are conditioned with dry saturated steam at a pressure of 6.0 MPa, and then extruded, cooled, crushed and screened by ring die to obtain irregular polyhedral three-dimensional core particles with a particle size of 1.5~4.5 mm. S2. Forming an inner coating layer: The first biodegradable polymer material is dissolved in an organic solvent to form an inner coating liquid, which is then atomized and sprayed onto the surface of the core particles in a fluidized bed coating equipment. After drying, an inner coating layer is formed. S3. Forming an outer coating layer: The second biodegradable polymer material and the inorganic salt micropore forming agent are dispersed or dissolved in a solvent to form an outer coating liquid. This liquid is then atomized and sprayed onto the surface of the particles that have been coated with the inner layer. After drying, an outer coating layer is formed.

[0016] Furthermore, in step S1, the sieving is carried out using a rotary grading sieve with an upper sieve mesh size of 4.5 mm and a lower sieve mesh size of 1.5 mm. After sieving, probiotic liquid is sprayed onto the surface of qualified particles to give the fertilizer biological control and growth promotion functions.

[0017] Furthermore, 0.5% to 5% of humic acid or seaweed extract by mass is added to the coating solution in steps S2 and S3. This not only fine-tunes the hydrophilicity of the coating to optimize the release curve, but also enhances its chelation and growth-stimulating effects.

[0018] The present invention also provides a method for regulating the release rate of crushed granular controlled-release organic fertilizer. By adjusting the type, proportion and particle size of the inorganic salt micropore forming agent in the outer coating layer, and adjusting the thickness ratio of the inner coating layer and the outer coating layer, the nutrient release period can be customized within the range of 30 days to 180 days.

[0019] This invention also provides an application of crushed granular slow-release organic fertilizer in the growth process of grain crops, cash crops or fruits and vegetables. The organic fertilizer is used as a base fertilizer or seed fertilizer and is applied once at the time of sowing or during the seedling stage of the crop. It is used to meet the needs of the target crop for organic matter and core nutrients throughout the entire growth period or key growth period, and to avoid root burn.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. Controllable and efficient nutrient release: The double-layer coating structure provides a double control barrier; when the outer coating layer comes into contact with water, the inorganic salt micropore-forming agent dissolves to form microchannels, initiating slow release in the initial stage; the inner coating layer, as the main control barrier, determines the medium- and long-term nutrient release rate through its slow biodegradation process, making the release curve better match the crop growth needs, and improving fertilizer utilization by more than 30%. 2. Safe application and prevention of root burn: The dense coating layer effectively prevents high-concentration nutrients from directly contacting the seeds or seedling roots in the early stage of fertilization, avoiding the seedling burn phenomenon common in traditional organic fertilizers, making it possible to sow seeds and fertilizer at the same time. 3. Structural design optimization: Irregular polyhedral particles have a larger specific surface area than spherical particles, which not only facilitates the adhesion of coating liquid and forms a more uniform and firm film layer, but also increases the contact surface with the soil, which is conducive to the balanced release of nutrients. 4. Mature technology, suitable for industrialization: The provided preparation method integrates standard fertilizer processing equipment and clarifies key process parameters, ensuring product consistency and production repeatability, and making it easy to achieve large-scale production; 5. Strong functional expandability: By adding substances such as humic acid to the coating solution and then spraying probiotics on the surface of the particles, additional functions such as promoting growth and improving soil can be added to the product, thereby enhancing the product value. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating the preparation method of slow-release organic fertilizer made from crushed granules. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1: Preparation of Controlled-Release Organic Fertilizer

[0024] I. Preparation of Organic Fertilizer Core Particles: 1. Take fully decomposed chicken manure and straw as raw materials (organic matter content about 60%, total nutrients about 8%), and feed them into a twin-shaft differential speed mixer to mix for 120 seconds. After mixing, the material is crushed by a water droplet-type pulverizer with a hammer screen aperture of 2.0mm. The crushed material enters a steam conditioning granulator, where it is conditioned and softened by 6.0MPa dry saturated steam. Then, it is fed into a ring die granulator to be extruded into strips and cut into segments to form irregular polygonal granules as the initial product.

[0025] 2. The particles are cooled to below room temperature by a counter-current cooler. After cooling, the particles are slightly crushed by a double-roll cross-grooved crusher and then enter a rotary grading screen. Particles that pass through the 4.5mm screen but remain on the 1.5mm screen are considered qualified products.

[0026] 3. Spray the surface of qualified granules with Bacillus subtilis bacterial solution (effective viable bacteria count ≥500 million / g), and dry at low temperature to obtain organic fertilizer core granules A, whose particle size is mainly concentrated in 2.0~4.0mm, organic matter content is about 55%, and total nutrients are about 7.5%.

[0027] II. Formation of a double-layered membrane: 1. Preparation of inner coating solution: Dissolve polylactic acid (PLA) in dichloromethane to form a solution with a mass concentration of 8%.

[0028] 2. Preparation of outer coating solution: Dissolve hydroxypropyl methylcellulose (HPMC) in water to form a 10% solution by mass, then add potassium sulfate powder with a particle size of about 30μm, which is equivalent to 20% of the mass of HPMC, and stir evenly.

[0029] 3. Place core particle A in a fluidized bed coating equipment. First, spray the inner coating solution onto the particle surface in an atomized manner and dry it with hot air to form an inner layer with a thickness of about 30 μm. Then, spray the outer coating solution onto the particles with the inner layer and dry it with hot air to form an outer layer with a thickness of about 60 μm. The total mass of the coating layer accounts for about 8% of the total mass of the finished product.

[0030] The controlled-release organic fertilizer product P1 is obtained through the above steps. Example 2: Preparation of controlled-release organic fertilizer with different components

[0031] Following the process flow of Example 1, but adjusting the formula of the core particles, using well-rotted pig manure, mushroom residue, and a small amount of inorganic nitrogen, phosphorus, and potassium raw materials for compounding, the final core particle B composition is: organic matter 45%, N 8%, P2O5 2%, K2O 2%, and total nutrients ((N+P2O5+K2O)) 12%. The coating process is the same as in Example 1.

[0032] The controlled-release organic fertilizer product P2 is obtained through the above steps. Example 3: Adjusting the coating process to change the release period

[0033] Core particle B was prepared according to Example 2.

[0034] Preparation of inner coating solution: Use polyhydroxyalkanoates (PHA) with a slower degradation rate.

[0035] Prepare the outer coating solution: reduce the amount of potassium sulfate added to 10% and replace it with some sodium chloride (particle size 20μm).

[0036] During coating, the inner layer thickness is increased to approximately 45 μm, and the outer layer thickness is reduced to approximately 40 μm.

[0037] The controlled-release organic fertilizer product P3 was produced, with a designed release period longer than that of P2. Example 4: Field Effect Trial

[0038] The experimental crop was summer maize, and two control groups, 1 and 2, were set up, as detailed below: Experimental group: When sowing, apply product P2 of this invention in a furrow 5cm below and to the side of the seed once, at a rate of 40 kg / mu.

[0039] Control group 1: Ordinary granular organic fertilizer (same formula, uncoated) with the same nutrient content was applied in furrows at the same location at the time of sowing.

[0040] Control group 2: Conventional fertilization, with 30 kg / mu of ordinary organic fertilizer applied as basal fertilizer and 15 kg / mu of urea applied as top dressing during the large trumpet stage.

[0041] According to the test results: The germination rate of the experimental group was significantly higher than that of the control group 1 (no seedling burn), and the seedlings grew vigorously during the seedling stage. Throughout the growth period, the experimental group showed robust growth and dark green leaves, performing similarly to control group 2 (which received two fertilizations). After harvest, the yield of the experimental group was measured. The yield of the experimental group was 18% higher than that of the control group 1, and there was no significant difference in yield between the experimental group and the control group 2.

[0042] The above results show that the controlled-release organic fertilizer of the present invention can achieve or even surpass the effect of traditional two-time fertilization by applying it only once as a base fertilizer, thus achieving the goals of labor saving, high efficiency and safety.

[0043] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A slow-release organic fertilizer made from crushed granules, characterized in that, include: Organic fertilizer core particles are irregular polyhedral particles containing organic matter, nitrogen, phosphorus, potassium, and trace elements. The controllable degradable coating layer consists of an inner coating layer and an outer coating layer, wherein: The inner membrane layer is a first biodegradable polymer material layer with strong hydrophobicity and slow degradation rate; The outer coating layer is a second biodegradable polymer material layer with strong hydrophilicity and containing inorganic salt micropore-forming agents.

2. The slow-release organic fertilizer made from crushed granules according to claim 1, characterized in that, By mass percentage, the total nutrient content of nitrogen, phosphorus and potassium in the core particles of the organic fertilizer is 20% to 50%, and the organic matter content is 25% to 60%.

3. The slow-release organic fertilizer made from crushed granules according to claim 1, characterized in that, The raw materials for the organic fertilizer core particles include at least one of livestock and poultry manure, crop straw, kitchen waste, and mushroom residue, and are subjected to aerobic fermentation until fully decomposed.

4. The crushed granular slow-release organic fertilizer according to claim 1, characterized in that, The total mass of the controllable degradable coating layer accounts for 3% to 15% of the total mass of the organic fertilizer, the thickness of the inner coating layer is 10 to 50 μm, and the thickness of the outer coating layer is 20 to 100 μm.

5. The slow-release organic fertilizer made from crushed granules according to claim 1, characterized in that, The first biodegradable polymer material layer is made of at least one of polylactic acid, polyhydroxyalkanoate, and polycaprolactone; the second biodegradable polymer material layer is made of at least one of starch-based plastic, cellulose derivative, and polybutylene succinate; the inorganic salt micropore forming agent is made of at least one of sodium chloride, potassium sulfate, and ammonium phosphate, with a particle size of 10-50 μm, accounting for 5%-30% of the mass of the outer coating layer.

6. A method for preparing a slow-release organic fertilizer made from crushed granules as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of organic fertilizer core particles: After the decomposed organic raw materials are mixed and crushed, they are conditioned with dry saturated steam at a pressure of 6.0 MPa, and then extruded, cooled, crushed and screened by ring die to obtain irregular polyhedral three-dimensional core particles with a particle size of 1.5~4.5 mm. S2. Forming an inner coating layer: The first biodegradable polymer material is dissolved in an organic solvent to form an inner coating liquid, which is then atomized and sprayed onto the surface of the core particles in a fluidized bed coating equipment. After drying, an inner coating layer is formed. S3. Forming an outer coating layer: The second biodegradable polymer material and the inorganic salt micropore forming agent are dispersed or dissolved in a solvent to form an outer coating liquid. This liquid is then atomized and sprayed onto the surface of the particles that have been coated with the inner layer. After drying, an outer coating layer is formed.

7. The method for preparing crushed granular slow-release organic fertilizer according to claim 6, characterized in that, In step S1, the sieving is carried out using a rotary grading sieve with an upper sieve mesh size of 4.5 mm and a lower sieve mesh size of 1.5 mm; after sieving, probiotic liquid is sprayed onto the surface of qualified particles.

8. The method for preparing crushed granular slow-release organic fertilizer according to claim 6, characterized in that, The coating solution in steps S2 and S3 also contains 0.5% to 5% humic acid or seaweed extract by mass of the coating solution.

9. A method for controlling the release rate of crushed granular slow-release organic fertilizer as described in any one of claims 1 to 5, characterized in that, By adjusting the type, proportion, and particle size of the inorganic salt micropore-forming agent in the outer coating layer, and by adjusting the thickness ratio of the inner coating layer to the outer coating layer, the nutrient release period can be customized within the range of 30 to 180 days.

10. An application of the crushed granular slow-release organic fertilizer as described in any one of claims 1 to 5 in the growth process of grain crops, cash crops or fruits and vegetables, wherein the organic fertilizer is used as a base fertilizer or seed fertilizer and applied once at the time of sowing or during the seedling stage of the crop to meet the needs of the target crop for organic matter and core nutrients throughout the entire growth period or key growth period, and to avoid root burn.

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