Organic fertilizer containing coconut waste and preparation method thereof

Abstract

The invention relates to the technical field of organic fertilizers, and mainly relates to an organic fertilizer containing coconut wastes and a preparation method thereof. The organic fertilizer containing the coconut waste comprises the following components in parts by weight: 95-105 parts of enzymolysis coco coir; 10 to 20 parts of modified coconut shell charcoal; 1 to 5 parts of urea; 3-8 parts of soluble starch; 0.1 to 2 parts of glycerol; and 0.1-1 part of boric acid. The preparation method of the organic fertilizer prepared from the coconut waste comprises the following steps: preparing soluble starch, boric acid, glycerol and water into a starch solution; heating the starch solution to 83-88 DEG C, and stirring until the starch solution is completely gelatinized to obtain a gelatinized starch solution; uniformly mixing the enzymolysis coco coir, the modified coconut shell charcoal and urea to obtain a mixed material; arranging the gelatinized starch solution on the surface of the mixed material to obtain a spraying mixture; and drying the spraying mixture to obtain the organic fertilizer containing the coconut waste. The coconut waste degradation efficiency can be improved, and long-acting slow release of nutrients can be achieved.

Description

Technical Field

[0001] This application relates to the field of organic fertilizer technology, and mainly to an organic fertilizer containing coconut waste and its preparation method. Background Technology

[0002] Organic fertilizer is made from organic matter such as plant and animal residues and industrial waste through microbial decomposition or chemical transformation. It offers advantages such as improving soil structure, enhancing soil fertility, promoting crop growth, and reducing reliance on chemical fertilizers. Its core value lies in realizing the resource utilization of agricultural waste while maintaining soil ecological balance through the slow release of nutrients, making it a crucial support for sustainable agricultural development. Organic fertilizer containing coconut waste uses coconut coir, coconut shells, and other byproducts of the coconut industry as raw materials. It not only solves the waste disposal problem but also improves fertilizer performance through enzymatic hydrolysis and biochar modification technologies, exhibiting significant environmental and economic value.

[0003] However, traditional organic fertilizers often face the problem of fluctuating nutrient release, characterized by "excessive release in the early stages and insufficient release in the later stages." This is especially true when using coconut waste as raw material, as the high fiber content and dense structure of coconut coir result in a natural degradation cycle that can last for several months, hindering its efficient utilization. While ordinary biochar can adsorb nutrients, it suffers from uncontrollable release rates, affecting crop absorption efficiency.

[0004] Therefore, developing organic fertilizers that can both improve the degradation efficiency of coconut waste and achieve long-term slow release of nutrients has become an urgent need for the industry. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide an organic fertilizer containing coconut waste and a method for preparing the same.

[0006] The technical solution of this application is as follows: An organic fertilizer containing coconut waste comprises the following raw materials in parts by weight: Enzymatic hydrolysis of coconut coir: 95-105 parts by weight; Modified coconut shell biochar: 10-20 parts by weight; Urea: 1-5 parts by weight; Soluble starch: 3-8 parts by weight; Glycerin: 0.1-2 parts by weight; Boric acid: 0.1-1 parts by weight.

[0007] Furthermore, the preparation of enzymatically hydrolyzed coconut coir includes the following steps: Mix coconut coir with water and let stand for 2-4 hours to obtain a coconut coir mixture. Adjust the pH of the coconut coir mixture to 5.0-5.5, add cellulase and hemicellulase to obtain a mixture; The mixture was enzymatically hydrolyzed at 50-60℃ for 30-40 hours; then the enzyme was inactivated to obtain crude coconut coir hydrolysate. The crude enzymatic hydrolysate of coconut coir is filtered and dried to obtain enzymatically hydrolyzed coconut coir.

[0008] Furthermore, when adding cellulase and hemicellulase, sodium dodecyl sulfate is also added, followed by ultrasonic treatment to obtain a mixture.

[0009] Furthermore, the preparation of modified coconut shell biochar includes the following steps: Coconut shells are carbonized at 480-520℃ for 1.5-2.5 hours in an oxygen-deficient environment to obtain coconut shell biochar. Coconut shell biochar is immersed in a 5-10% potassium dihydrogen phosphate solution for 20-40 minutes. Then, microwave irradiation is applied for 1-5 minutes at a power of 500-600W. Then, it is dried to constant weight to obtain modified coconut shell biochar.

[0010] Furthermore, in the preparation of modified coconut shell biochar, after drying to constant weight, it is rinsed with 0.1-0.5M calcium hydroxide solution until pH=7±0.5, and then dried again to constant weight to obtain modified coconut shell biochar. When coconut shell biochar is immersed in a 5-10% potassium dihydrogen phosphate solution, it is immersed for 20-40 minutes under a vacuum of -0.08±0.02MPa.

[0011] Furthermore, the weight of cellulase is 0.1-1% of the weight of coconut coir, and the weight of hemicellulase is 0.1-1% of the weight of coconut coir.

[0012] Leaching with calcium hydroxide can further neutralize the acidity on the surface of coconut shell biochar, preventing adverse effects on plant growth. Calcium hydroxide reacts with acidic substances on the surface of coconut shell biochar to produce salts such as calcium phosphate, further increasing the phosphorus content of the modified coconut shell biochar.

[0013] Furthermore, the amount of sodium dodecyl sulfate added is 0.01-0.1% of the weight of coconut coir; The conditions for ultrasonic treatment are ultrasonic power of 300-400W, frequency of 25-30kHz, and ultrasonic time of 1-2h.

[0014] This application also provides a method for preparing organic fertilizer containing coconut waste, comprising the following steps: A starch solution is prepared by mixing soluble starch, boric acid, glycerin, and water. The starch solution is heated to 83-88℃ and stirred until completely gelatinized to obtain a gelatinized starch solution. The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture. A gelatinized starch solution is placed on the surface of the mixture to obtain a sprayed mixture; The mixture is dried and sprayed to obtain organic fertilizer containing coconut waste.

[0015] Furthermore, when the gelatinized starch solution is placed on the surface of the mixture, the coating thickness is controlled to be 0.1-0.3 mm.

[0016] Furthermore, the total weight ratio of soluble starch, boric acid, and glycerol to water is 1:(10-15).

[0017] First, enzymatic pretreatment, through the synergistic degradation of cellulase and hemicellulase, not only releases readily available nutrients from coconut coir but also significantly increases its porosity and specific surface area by disrupting the plant cell wall structure—this structural modification directly creates an "anchorable interface" for subsequent biochar loading. Without enzymatic activation, the porous structure of biochar would be difficult to effectively adsorb or chemically bind due to the dense matrix, resulting in weak nutrient storage capacity.

[0018] Secondly, the preparation of phosphate-modified biochar is highly dependent on the loose matrix after enzymatic hydrolysis: vacuum impregnation requires the use of the porous channels created by enzymatic hydrolysis to allow potassium dihydrogen phosphate to permeate evenly into the biochar pores; microwave irradiation promotes the chemical bonding between phosphate and the biochar surface through localized heating; and calcium hydroxide rinsing utilizes the pH environment of the mixture after enzymatic hydrolysis to achieve acid neutralization and phosphorus stabilization. If the enzymatic hydrolysis step is skipped, the biochar modification will lack effective adsorption sites, making it difficult to form a dual nutrient reserve system of "physical adsorption-chemical fixation," thus losing the basis for slow-release regulation.

[0019] Finally, the formation of the starch coating is supported by the structural modifications of both components: the loose coconut coir pretreated by enzymatic hydrolysis and the porous structure of the modified biochar together constitute the "attachment framework" of the coating, while the cross-linking reaction of boric acid and the plasticizing effect of glycerol in the coating need to be completed under specific pH and structural conditions, ultimately forming a physical barrier that combines water resistance and flexibility. This barrier integrates the readily available nutrients produced by enzymatic hydrolysis and the slowly available nutrients stored in biochar into a gradient release system of "initial rapid fertilization - mid-term stable release - late-term continuous supply" by regulating the water permeation rate.

[0020] The synergistic effect of enzymatic pretreatment, phosphate modification and starch coating constitutes a progressive modification chain of "matrix activation - nutrient storage - release regulation". The three are inseparable synergistic whole through strict dependence on the process sequence. The absence of any step will lead to the failure of the overall sustained-release performance.

[0021] Compared with the prior art, this application has the following beneficial effects: 1. Enzymatic hydrolysis pretreatment converts macromolecules of coconut coir into small-molecule active substances, activating soil microbial metabolism; modified coconut shell biochar enhances nutrient adsorption sites by introducing phosphate groups, promoting microbial nitrogen fixation and phosphorus solubilization; the two work synergistically to improve nutrient bioavailability, while the slow-release properties of the starch coating ensure the continuous release of active substances and nutrients, forming a continuous chain of action of "activation-adsorption-slow release", strengthening the virtuous cycle of soil microecology and nutrient utilization.

[0022] 2. The starch coating forms a semi-permeable membrane structure through the dynamic balance of boric acid crosslinking and glycerol plasticization, enabling gradient release of nutrients; the porous structure and active sites of modified coconut shell biochar further delay nutrient loss, and the two together construct a dual guarantee of "controlled release-retention" to reduce leaching and volatilization; the physical structure optimized by enzymatic hydrolysis pretreatment enhances the soil's water and fertilizer retention capacity, and the three work together to achieve a system optimization of "precise controlled release, long-lasting retention, and healthy soil".

[0023] 3. Enzymatic hydrolysis pretreatment and modified coconut shell biochar utilize coconut waste to achieve resource utilization; the starch coating uses biodegradable materials, which decompose naturally without pollution; the three together construct a green cycle of "waste utilization - environmental friendliness - continuous effectiveness", which not only reduces environmental pollution, but also forms a sustainable fertilizer system of "short-term efficiency enhancement - long-term sustainability" through long-term nutrient release and soil improvement, reflecting the integrated advantages of "resource recycling - environmental friendliness - excellent performance". Detailed Implementation

[0024] To facilitate understanding of this application, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of this application.

[0025] This application provides an organic fertilizer containing coconut waste, comprising the following raw materials by weight: Enzymatic hydrolysis of coconut coir: 95-105 parts by weight; Modified coconut shell biochar: 10-20 parts by weight; Urea: 1-5 parts by weight; Soluble starch: 3-8 parts by weight; Glycerin: 0.1-2 parts by weight; Boric acid: 0.1-1 parts by weight.

[0026] This application also provides a method for preparing organic fertilizer containing coconut waste, comprising the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 1-5mm.

[0027] Step 2: Enzymatic pretreatment: Mix the crushed coconut coir with water, stir well, and let stand for 2-4 hours to obtain a coconut coir mixture. The mass ratio of coconut coir to water is 1:(5-8).

[0028] Then, use citric acid to adjust the pH of the coconut coir mixture to 5.0-5.5.

[0029] Add cellulase and hemicellulase, and stir well to obtain a mixture. The weight of cellulase is 0.1-1% of the weight of coconut coir, and the weight of hemicellulase is 0.1-1% of the weight of coconut coir.

[0030] Place the mixture in a constant temperature water bath shaker at 50-60℃ and shake at a speed of 110-130rpm for 30-40 hours.

[0031] Then add sodium carbonate to adjust the pH to 8.0-9.0, heat to 70-90℃, and maintain for 2-3 hours to inactivate the enzyme, thus obtaining the crude enzymatic hydrolysate of coconut coir.

[0032] The crude enzymatic hydrolysate of coconut coir is filtered, dried, and pulverized to obtain enzymatically hydrolyzed coconut coir.

[0033] To improve the enzymatic hydrolysis effect, sodium dodecyl sulfate can be added when adding cellulase and hemicellulase, and ultrasonic treatment can be performed at the same time to promote mixing, so as to obtain a mixture.

[0034] The amount of sodium dodecyl sulfate added is 0.01-0.1% of the weight of coconut coir.

[0035] The parameters for ultrasonic treatment are ultrasonic power of 300-400W, frequency of 25-30kHz, and ultrasonic time of 1-2h.

[0036] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in a carbonization furnace at 480-520℃ for 1.5-2.5 hours under oxygen-deficient conditions, and then cooled to obtain coconut shell biochar.

[0037] Step 4: Preparation of modified coconut shell biochar: Immerse coconut shell biochar in a 5-10% potassium dihydrogen phosphate solution for 20-40 minutes under vacuum (vacuum degree -0.08±0.02MPa). The weight ratio of coconut shell biochar to potassium dihydrogen phosphate solution is 1:(10-20).

[0038] Microwave irradiation is used for 1-5 minutes, with a microwave power of 500-600W.

[0039] The impregnated biochar was dried at 75-85℃ to constant weight, then rinsed with 0.1-0.5M calcium hydroxide solution until pH=7±0.5, and dried again to constant weight to obtain modified coconut shell biochar.

[0040] Step 5: Starch coating: Soluble starch, boric acid, and glycerol are dissolved in water to prepare a starch solution. The weight ratio of soluble starch to boric acid and glycerol is 1:(0.05-0.1):(0.1-0.3). The weight ratio of the total weight of soluble starch, boric acid, and glycerol to water is 1:(10-15).

[0041] Heat the starch solution to 83-88℃ and stir until completely gelatinized to obtain a gelatinized starch solution.

[0042] The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0043] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.1-0.3 mm to obtain the sprayed mixture.

[0044] The sprayed mixture is dried in an oven at 55-65℃ until the moisture content is less than 10%, yielding organic fertilizer containing coconut waste.

[0045] Regarding starch coating: During the gelatinization process of soluble starch upon heating, its molecular chains unfold to form a three-dimensional network framework. At this time, boric acid molecules undergo a reversible esterification reaction with the ortho-hydroxyl groups on the starch chains, establishing chemical cross-linking bridges between molecules. This process not only enhances the water barrier properties of the network but also endows the coating with a certain stress relaxation capability through the dynamic reversibility of the cross-linking points. Glycerol, on the other hand, embeds itself in the interstices of the starch network, weakening the van der Waals forces between molecular chains through hydrogen bonding. While lowering the glass transition temperature, it forms a complementary structure with the boric acid cross-linking points, combining rigidity and flexibility. The chemical cross-linking of boric acid provides rigid support, preventing excessive swelling of the coating; the physical plasticizing of glycerol imparts flexibility and extensibility, avoiding drying shrinkage and cracking.

[0046] The starch network provides sites for boric acid crosslinking, creating a spatial structure for glycerol insertion. Boric acid crosslinking fixes the network backbone through chemical bonds while simultaneously regulating the degree of freedom of glycerol molecules. Glycerol, by adjusting molecular chain fluidity, reacts to the stress distribution of the crosslinked network, ultimately forming a dynamic equilibrium system integrating film formation, reinforcement, and plasticization. This unique combination enables the coating to maintain a thin 0.1-0.3 mm film while possessing multiple properties such as non-collapse upon contact with water, non-cracking under pressure, and non-decomposition upon heat drying.

[0047] The present application will be further described below through specific embodiments.

[0048] Example 1 An organic fertilizer containing coconut waste includes the following raw materials: Enzymatic hydrolysis of coconut coir: 100kg; Modified coconut shell biochar: 15kg; Urea: 2 kg; Soluble starch: 4 kg (commercially available, CAS number used in this example is 9005-84-9); Glycerin: 0.7 kg; Boric acid: 0.3 kg.

[0049] This embodiment also discloses a method for preparing organic fertilizer containing coconut waste, including the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 2mm.

[0050] Step 2: Enzymatic pretreatment: Mix the crushed coconut coir with water, stir well, and let stand for 3 hours to obtain the coconut coir mixture. The mass ratio of coconut coir to water is 1:6.

[0051] Then, citric acid was used to adjust the pH of the coconut coir mixture to 5.2.

[0052] Add cellulase and hemicellulase, and stir well to obtain a mixture. The cellulase is 0.3% of the weight of coconut coir (commercially available, CAS number used in this example is 9012-54-8); the hemicellulase is 0.2% of the weight of coconut coir (commercially available, CAS number used in this example is 9025-56-3).

[0053] The mixture was placed in a constant temperature water bath shaker at 55°C and shaken at 120 rpm for 36 hours.

[0054] Then, sodium carbonate was added to adjust the pH to 8.5, the temperature was raised to 80℃, and the enzyme was inactivated for 3 hours to obtain the crude enzymatic hydrolysate of coconut coir.

[0055] The crude enzymatic hydrolysate of coconut coir is filtered, dried, and pulverized to obtain enzymatically hydrolyzed coconut coir.

[0056] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in an oxygen-deficient furnace at 500°C for 2 hours, and then cooled to obtain coconut shell biochar.

[0057] Step 4: Preparation of modified coconut shell biochar: Coconut shell biochar was immersed in an 8% potassium dihydrogen phosphate solution for 30 minutes under vacuum (0.08 MPa). The weight ratio of coconut shell biochar to potassium dihydrogen phosphate solution was 1:10.

[0058] Microwave irradiation was applied for 3 minutes at a power of 600W.

[0059] The impregnated biochar was dried at 80°C to constant weight, and then rinsed with 0.1M calcium hydroxide solution until pH=7 to obtain modified coconut shell biochar.

[0060] Step 5: Starch coating: Soluble starch, boric acid, and glycerol are dissolved in water to prepare a starch solution. The total weight ratio of soluble starch, boric acid, and glycerol to water is 1:10.

[0061] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0062] The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0063] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0064] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0065] Performance testing: 1. Organic matter content: The organic matter content was determined in accordance with NY / T 525-2021 "Organic Fertilizer".

[0066] 2. Slow-release performance: The cumulative release rate and release period of total nutrients (nitrogen and potassium) at 24 hours and 28 days were determined in accordance with GB / T 23348-2009 "Slow-release Fertilizers" at a temperature of 25℃.

[0067] Test results: 1. Organic matter content: 58%.

[0068] 2. Cumulative release rate at 24 hours: 10.5%; Cumulative release rate at 28 days: 42.3%; Release period: 90 days.

[0069] Example 2 An organic fertilizer containing coconut waste includes the following raw materials: Enzymatic hydrolysis of coconut coir: 100kg; Modified coconut shell biochar: 15kg; Urea: 2 kg; Soluble starch: 4 kg (commercially available, CAS number used in this example is 9005-84-9); Glycerin: 0.7 kg; Boric acid: 0.3 kg.

[0070] This embodiment also discloses a method for preparing organic fertilizer containing coconut waste, including the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 2mm.

[0071] Step 2: Enzymatic pretreatment: Mix the crushed coconut coir with water, stir well, and let stand for 3 hours to obtain the coconut coir mixture. The mass ratio of coconut coir to water is 1:6.

[0072] Then, citric acid was used to adjust the pH of the coconut coir mixture to 5.2.

[0073] Add cellulase, hemicellulase, and sodium dodecyl sulfate, stir until homogeneous, and then sonicate under ultrasonic power of 300-400W, frequency of 25-30kHz, and ultrasonic time of 1-2h to obtain a mixture. The cellulase is 0.3% of the weight of coconut coir (commercially available, CAS number 9012-54-8 used in this example); the hemicellulase is 0.2% of the weight of coconut coir (commercially available, CAS number 9025-56-3 used in this example); and the amount of sodium dodecyl sulfate added is 0.05% of the weight of coconut coir.

[0074] The mixture was placed in a constant temperature water bath shaker at 55°C and shaken at 120 rpm for 36 hours.

[0075] Then, sodium carbonate was added to adjust the pH to 8.5, the temperature was raised to 80℃, and the enzyme was inactivated for 3 hours to obtain the crude enzymatic hydrolysate of coconut coir.

[0076] The crude enzymatic hydrolysate of coconut coir is filtered, dried, and pulverized to obtain enzymatically hydrolyzed coconut coir.

[0077] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in an oxygen-deficient furnace at 500°C for 2 hours, and then cooled to obtain coconut shell biochar.

[0078] Step 4: Preparation of modified coconut shell biochar: Coconut shell biochar was immersed in an 8% potassium dihydrogen phosphate solution for 30 minutes under vacuum (0.08 MPa). The weight ratio of coconut shell biochar to potassium dihydrogen phosphate solution was 1:10.

[0079] Microwave irradiation was applied for 3 minutes at a power of 600W.

[0080] The impregnated biochar was dried at 80°C to constant weight, and then rinsed with 0.1M calcium hydroxide solution until pH=7 to obtain modified coconut shell biochar.

[0081] Step 5: Starch coating: Soluble starch, boric acid, and glycerol are dissolved in water to prepare a starch solution. The total weight ratio of soluble starch, boric acid, and glycerol to water is 1:10.

[0082] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0083] The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0084] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0085] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0086] Test results: 1. Organic matter content: 62%.

[0087] 2. Cumulative release rate at 24 hours: 9.7%; Cumulative release rate at 28 days: 40.8%; Release period: 90 days.

[0088] Comparative Example 1 The difference from Example 1 is that boric acid is omitted in step 5, as follows: Step 5: Starch coating: Soluble starch and glycerin are dissolved in water to prepare a starch solution. The total weight ratio of soluble starch and glycerin to water is 1:10.

[0089] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0090] The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0091] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0092] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0093] Test results: 1. Organic matter content: 53%.

[0094] 2. Cumulative release rate at 24 hours: 14.8%; Cumulative release rate at 28 days: 51.6%; Release period: 70 days.

[0095] Comparative Example 2 An organic fertilizer containing coconut waste includes the following raw materials: Pre-treated coconut coir: 100kg; Modified coconut shell biochar: 15kg; Urea: 2 kg; Soluble starch: 4kg (commercially available, CAS number 9005-84-9); Glycerin: 0.7 kg; Boric acid: 0.3 kg.

[0096] This comparative example also discloses a method for preparing organic fertilizer containing coconut waste, including the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 2mm.

[0097] Step 2: Preprocessing: Mix the crushed coconut coir with water, stir well, and let stand for 3 hours to obtain the coconut coir mixture. The mass ratio of coconut coir to water is 1:6.

[0098] The coconut coir mixture is filtered, dried, and pulverized to obtain pretreated coconut coir.

[0099] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in an oxygen-deficient furnace at 500°C for 2 hours, and then cooled to obtain coconut shell biochar.

[0100] Step 4: Preparation of modified coconut shell biochar: Coconut shell biochar was immersed in an 8% potassium dihydrogen phosphate solution for 30 minutes under vacuum (0.08 MPa). The weight ratio of coconut shell biochar to potassium dihydrogen phosphate solution was 1:10.

[0101] Microwave irradiation was applied for 3 minutes at a power of 600W.

[0102] The impregnated biochar was dried at 80°C to constant weight, and then rinsed with 0.1M calcium hydroxide solution until pH=7 to obtain modified coconut shell biochar.

[0103] Step 5: Starch coating: Soluble starch, boric acid, and glycerol are dissolved in water to prepare a starch solution. The total weight ratio of soluble starch, boric acid, and glycerol to water is 1:10.

[0104] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0105] The pretreated coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0106] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0107] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0108] Test results: 1. Organic matter content: 46.5%.

[0109] 2. Cumulative release rate at 24 hours: 14.4%; Cumulative release rate at 28 days: 49.8%; Release period: 70 days.

[0110] Comparative Example 3 An organic fertilizer containing coconut waste includes the following raw materials: Enzymatic hydrolysis of coconut coir: 100kg; Coconut shell biochar: 15kg; Urea: 2 kg; Soluble starch: 4kg (commercially available, CAS number 9005-84-9); Glycerin: 0.7 kg; Boric acid: 0.3 kg.

[0111] This comparative example also discloses a method for preparing organic fertilizer containing coconut waste, including the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 2mm.

[0112] Step 2: Enzymatic pretreatment: Mix the crushed coconut coir with water, stir well, and let stand for 3 hours to obtain the coconut coir mixture. The mass ratio of coconut coir to water is 1:6.

[0113] Then, citric acid was used to adjust the pH of the coconut coir mixture to 5.2.

[0114] Add cellulase and hemicellulase, and stir well to obtain a mixture. The cellulase is 0.3% of the weight of coconut coir (commercially available, CAS No. 9012-54-8); the hemicellulase is 0.2% of the weight of coconut coir (commercially available, CAS No. 9025-56-3).

[0115] The mixture was placed in a constant temperature water bath shaker at 55°C and shaken at 120 rpm for 36 hours.

[0116] Then, sodium carbonate was added to adjust the pH to 8.5, the temperature was raised to 80℃, and the enzyme was inactivated for 3 hours to obtain the crude enzymatic hydrolysate of coconut coir.

[0117] The crude enzymatic hydrolysate of coconut coir is filtered, dried, and pulverized to obtain enzymatically hydrolyzed coconut coir.

[0118] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in an oxygen-deficient furnace at 500°C for 2 hours, and then cooled to obtain coconut shell biochar.

[0119] Step 4: Starch coating: Soluble starch, boric acid, and glycerol are dissolved in water to prepare a starch solution. The total weight ratio of soluble starch, boric acid, and glycerol to water is 1:10.

[0120] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0121] The enzymatically hydrolyzed coconut coir, coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0122] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0123] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0124] Test results: 1. Organic matter content: 49%.

[0125] 2. Cumulative release rate at 24 hours: 16.5%; Cumulative release rate at 28 days: 53.0%; Release period: 65 days.

[0126] Comparative Example 4 An organic fertilizer containing coconut waste includes the following raw materials: Pre-treated coconut coir: 100kg; Coconut shell biochar: 15kg; Urea: 2 kg; Soluble starch: 4kg (commercially available, CAS number 9005-84-9).

[0127] This comparative example also discloses a method for preparing organic fertilizer containing coconut waste, including the following steps: Step 1: Grind coconut coir: Crush the coconut coir (commercially available) using a grinder, controlling the particle size to 2mm.

[0128] Step 2: Preprocessing: Mix the crushed coconut coir with water, stir well, and let stand for 3 hours to obtain the coconut coir mixture. The mass ratio of coconut coir to water is 1:6.

[0129] The coconut coir mixture is filtered, dried, and pulverized to obtain pretreated coconut coir.

[0130] Step 3: Preparation of coconut shell biochar: Coconut shells (commercially available) are carbonized in an oxygen-deficient furnace at 500°C for 2 hours, and then cooled to obtain coconut shell biochar.

[0131] Step 4: Starch coating: Soluble starch is dissolved in water to prepare a starch solution. The weight ratio of soluble starch to water is 1:10.

[0132] Heat the starch solution to 85°C and stir until completely gelatinized to obtain a gelatinized starch solution.

[0133] The pretreated coconut coir, coconut shell biochar, and urea are mixed evenly to obtain a mixture.

[0134] The gelatinized starch solution is sprayed onto the surface of the mixture, and the coating thickness is controlled to be 0.2 mm to obtain the sprayed mixture.

[0135] The sprayed mixture was dried in an oven at 60°C until the moisture content was 8%, yielding organic fertilizer containing coconut waste.

[0136] Test results: 1. Organic matter content: 42%.

[0137] 2. Cumulative release rate at 24 hours: 18.8%; Cumulative release rate at 28 days: 59.0%; Release period: 40 days.

[0138] The test results show that the organic matter content and slow-release effect of the organic fertilizer containing coconut waste in Comparative Example 4 are far less significant than those in Examples 1 and 2. This indicates that the organic fertilizer containing coconut waste provided in this application can effectively utilize coconut waste and produce high-performance organic fertilizer.

[0139] Comparative Example 1, based on Example 1, disrupted the specific combination of starch coating; Comparative Example 2, based on Example 1, omitted the enzymatic hydrolysis pretreatment; and Comparative Example 3, based on Example 1, omitted the modification of coconut shell biochar. Comparison of the detected performance data shows that although the organic fertilizers containing coconut waste from Comparative Examples 1-3 outperformed Comparative Example 4 in various aspects, they still showed significant differences compared to Examples 1 and 2. This is mainly because the aforementioned comparative examples did not merely disrupt a single step or operation, but rather prevented the synergistic effect of enzymatic hydrolysis pretreatment, phosphate modification, and starch coating from being fully realized, thus leading to substantial changes in performance data.

[0140] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.

Claims

1. An organic fertilizer containing coconut waste, characterized in that, The following raw materials are included in the preparation according to parts by weight: Enzymatic hydrolysis of coconut coir: 95-105 parts by weight; Modified coconut shell biochar: 10-20 parts by weight; Urea: 1-5 parts by weight; Soluble starch: 3-8 parts by weight; Glycerin: 0.1-2 parts by weight; Boric acid: 0.1-1 parts by weight.

2. The organic fertilizer containing coconut waste according to claim 1, characterized in that, The preparation of enzymatically hydrolyzed coconut coir includes the following steps: Mix coconut coir with water and let stand for 2-4 hours to obtain a coconut coir mixture. Adjust the pH of the coconut coir mixture to 5.0-5.5, add cellulase and hemicellulase to obtain a mixture; The mixture was enzymatically hydrolyzed at 50-60℃ for 30-40 hours; then the enzyme was inactivated to obtain crude coconut coir hydrolysate. The crude enzymatic hydrolysate of coconut coir is filtered and dried to obtain enzymatically hydrolyzed coconut coir.

3. The organic fertilizer containing coconut waste according to claim 2, characterized in that, When cellulase and hemicellulase are added, sodium dodecyl sulfate is also added, followed by ultrasonic treatment to obtain a mixture.

4. The organic fertilizer containing coconut waste according to claim 1, characterized in that, The preparation of modified coconut shell biochar includes the following steps: Coconut shells are carbonized at 480-520℃ for 1.5-2.5 hours in an oxygen-deficient environment to obtain coconut shell biochar. Coconut shell biochar is immersed in a 5-10% potassium dihydrogen phosphate solution for 20-40 minutes. Then, microwave irradiation is applied for 1-5 minutes at a power of 500-600W. Then, it is dried to constant weight to obtain modified coconut shell biochar.

5. The organic fertilizer containing coconut waste according to claim 4, characterized in that, In the preparation of modified coconut shell biochar, after drying to constant weight, it is rinsed with 0.1-0.5M calcium hydroxide solution until pH=7±0.5, and then dried to constant weight again to obtain modified coconut shell biochar. When coconut shell biochar is immersed in a 5-10% potassium dihydrogen phosphate solution, it is immersed for 20-40 minutes under a vacuum of -0.08±0.02MPa.

6. The organic fertilizer containing coconut waste according to claim 2, characterized in that, The weight of cellulase is 0.1-1% of the weight of coconut coir, and the weight of hemicellulase is 0.1-1% of the weight of coconut coir.

7. The organic fertilizer containing coconut waste according to claim 3, characterized in that, The amount of sodium dodecyl sulfate added is 0.01-0.1% of the weight of coconut coir; The conditions for ultrasonic treatment are ultrasonic power of 300-400W, frequency of 25-30kHz, and ultrasonic time of 1-2h.

8. A method for preparing organic fertilizer containing coconut waste according to any one of claims 1-7, characterized in that, Includes the following steps: A starch solution is prepared by mixing soluble starch, boric acid, glycerin, and water. The starch solution is heated to 83-88℃ and stirred until completely gelatinized to obtain a gelatinized starch solution. The enzymatically hydrolyzed coconut coir, modified coconut shell biochar, and urea are mixed evenly to obtain a mixture. A gelatinized starch solution is placed on the surface of the mixture to obtain a sprayed mixture; The mixture is dried and sprayed to obtain organic fertilizer containing coconut waste.

9. The method for preparing organic fertilizer containing coconut waste according to claim 8, characterized in that, When the gelatinized starch solution is placed on the surface of the mixture, the coating thickness is controlled to be 0.1-0.3 mm.

10. The method for preparing organic fertilizer containing coconut waste according to claim 8, characterized in that, The total weight ratio of soluble starch, boric acid, and glycerol to water is 1:(10-15).