Composite organic fertilizer based on seaweed residues and oyster calcium and preparation method of composite organic fertilizer

Abstract

The invention discloses a composite organic fertilizer based on seaweed residues and oyster calcium and a preparation method thereof. The composite organic fertilizer comprises the following raw materials in parts by weight: 40-50 parts of seaweed residues, 20-30 parts of oyster calcium powder, 1-2 parts of a decomposition agent, 5-10 parts of a nitrogen source supplement, 5-8 parts of humic acid and 1-2 parts of a trace element additive. The compound organic fertilizer has the advantage of high nutritional value, and the problems that in the preparation process of an existing compound organic fertilizer, seaweed residues and oyster calcium are not convenient to use as raw materials to prepare the fertilizer, the two raw materials are difficult to decompose, and the nutritional value and the fertilizer efficiency of the organic fertilizer are reduced are solved.

Description

Technical Field

[0001] The invention relates to the technical field of organic fertilizers, in particular to a composite organic fertilizer based on seaweed residue and oyster calcium and a preparation method thereof. Background Art

[0002] Compound organic fertilizers are a type of fertilizer that combines various organic materials with appropriate amounts of inorganic ingredients. They are not only rich in organic matter, but also contain nitrogen, phosphorus, and potassium as primary nutrients, as well as calcium, magnesium, and sulfur as trace elements. Organic matter is derived from the composting of plant and animal residues and feces. This fertilizer is designed to improve soil fertility, improve soil structure, and provide a comprehensive and balanced nutrient supply for crops. Compound organic fertilizers based on seaweed residue and oyster calcium are unique organic fertilizers that combine the advantages of two natural resources: seaweed residue and oyster shells. This fertilizer is not only rich in various nutrients necessary for plant growth, but also improves soil structure and enhances crop resistance. Seaweed residue is typically the residual material left after processing various marine seaweeds. Seaweed itself is rich in minerals, vitamins, amino acids, and bioactive plant hormones such as cytokinins and gibberellins. Oyster calcium is primarily derived from crushed oyster shells. Oyster shells contain a large amount of calcium carbonate, making them an excellent source of calcium.

[0003] In the preparation process of existing compound organic fertilizers, it is inconvenient to use seaweed residue and oyster calcium as raw materials to prepare fertilizers, and it is difficult to decompose the two raw materials, which reduces the nutritional value and fertilizer efficiency of the organic fertilizer. Summary of the Invention

[0004] The object of the present invention is to provide a composite organic fertilizer based on seaweed residue and oyster calcium and a preparation method thereof, which has the advantage of high nutritional value and solves the problem that in the preparation process of existing composite organic fertilizers, it is inconvenient to use seaweed residue and oyster calcium as raw materials to prepare fertilizers, and it is difficult to decompose the two raw materials, thereby reducing the nutritional value and fertilizer efficiency of the organic fertilizer.

[0005] To achieve the above object, the present invention provides the following technical solution: a composite organic fertilizer based on seaweed residue and oyster calcium, comprising the following raw materials in parts by weight:

[0006] 40-50 parts of seaweed residue, 20-30 parts of oyster calcium powder, 1-2 parts of composting agent, 5-10 parts of nitrogen source supplement, 5-8 parts of humic acid, and 1-2 parts of trace element additives.

[0007] A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium comprises the following steps:

[0008] S1. Raw material pretreatment: seaweed residue and oyster calcium powder are pretreated. EM bacteria or Bacillus subtilis are used as composting agents, urea or ammonium sulfate is used as nitrogen source supplement, natural humic acid or fulvic acid is used as humic acid, and one or more of chelated boron, molybdenum or manganese is used as trace element additives;

[0009] S2. Mix the raw materials: seaweed residue, oyster calcium powder, composting agent and nitrogen source supplement according to the proportion of parts by weight, using a double-shaft paddle mixer for 10-15 minutes to ensure uniformity;

[0010] S3, composting fermentation, pre-treating the mixed fertilizer raw materials, adjusting the moisture content to 50-60%, and then piling them in a fermentation tank. The height of the fertilizer pile is 1.5-2 meters and the width is 2-3 meters. The temperature of the fermentation pile is first raised to 50-65℃ and maintained for 48-72 hours to kill pathogens, then lowered to 45-50℃ and fermented for 15-20 days. During the fermentation process, the pile is turned every 3 days to ensure oxygen supply and uniform fermentation;

[0011] S4. Adding functional ingredients: adding humic acid and trace element additives to the composted raw materials according to the proportion of parts by weight, and mixing them evenly using a double-shaft paddle mixer;

[0012] S5, granulation and molding, feeding the mixed material into a drum granulator, adjusting the speed of the drum granulator to 15-25 rpm, the granulation time to 30-45 minutes, and the particle size to 2-4 mm to prepare fertilizer granules.

[0013] 5. As a preferred preparation method of a composite organic fertilizer based on seaweed slag and oyster calcium of the present invention, when the seaweed slag is pretreated in S1, impurities on the seaweed slag are first cleaned out using a cleaning device, and then vacuum extrusion dehydration is performed. After dehydration, the seaweed slag is dried using a drying device, and after drying, the seaweed slag is crushed using a pulverizer, the particle size of the seaweed slag is controlled to 1-2 mm, and the crushed seaweed slag is mixed with an acetic acid-sodium acetate buffer solution with a pH of 5.0;

[0014] adding cellulase to the seaweed residue in a ratio of 100:2, extracting at 55°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 4.2 after the enzyme inactivation is completed; adding pectinase to the seaweed residue in a ratio of 100:1, extracting at 50°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 6.0 after the enzyme inactivation is completed; adding fibrinase to the seaweed residue in a ratio of 100:1, extracting at 55°C for 48 hours, and then inactivating the enzyme at 100°C for 5 minutes, to decompose the cellulose, pectin and protein in the seaweed residue, so that the subsequent composting effect is better;

[0015] During enzymatic hydrolysis processing, a multifunctional composite enzymatic hydrolysis reaction system is used. The multifunctional composite enzymatic hydrolysis reaction system includes a reaction tank system, a temperature control system, a stirring system, a pH adjustment system and an enzyme liquid adding system. The enzyme liquid adding system adds cellulase, pectinase and fibrinase into the reaction tank system through a multi-channel metering pump. The temperature control system controls the temperature inside the reaction tank system. The stirring system stirs and mixes the enzymes and raw materials inside the reaction tank system. During the stirring and mixing process, the pH adjustment system adjusts the pH value inside the reaction tank system. The temperature control system heats the raw materials and enzymes inside the reaction tank system through an electric heating jacket.

[0016] 6. As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, when pre-treating the oyster calcium powder in S1, the oyster shells are thoroughly cleaned with clean water, and then the oyster shells are placed in a well-ventilated place for drying, and the dried oyster shells are placed in a crushing and grinding device, first crushed into oyster shell fragments, and then ground into a fine powder;

[0017] The crushing and grinding equipment includes a feeding system, a crushing system, a grinding system, and a discharging and collecting system. The feeding system transports the oyster shells to the crushing system through a vibrating feeder. The crushing system is a hammer crusher, which crushes the oyster shells into fragments. The oyster fragments enter the grinding system. The grinding system is a ball mill. The ball mill grinds the oyster fragments through the collision and friction between the steel balls installed in the cylinder and the oyster fragments. The ground oyster shell powder enters the discharging and collecting system. The discharging and collecting system is equipped with multi-stage screening equipment to screen the oyster shell powder. The qualified oyster shell powder enters the finished product collection container, and the unqualified oyster powder flows back to the grinding system for further grinding.

[0018] As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, the twin-shaft paddle mixers in S2 and S4 add different types of raw materials to the feed port of the mixer according to a predetermined ratio during operation, and start the twin-shaft paddle mixer after the addition is completed. At this time, the two stirring shafts inside the twin-shaft paddle mixer start to rotate to drive the blades to work synchronously, so that the material is fully stirred in the space between the two shafts. During the mixing process, the blades cause the material to be subjected to axial thrust while also being subjected to radial dispersion force to break up the formed clumps and promote uniform distribution among the components. After the predetermined mixing time is completed, the machine is stopped, and the electric discharge valve is opened to discharge the raw materials inside the twin-shaft paddle mixer.

[0019] As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, 2-5 parts of bentonite, 1-2 parts of chitin and 1-2 parts of a composite bacterial agent are added to the fertilizer raw material in S3 during the fermentation process, and are evenly mixed with the fertilizer raw material to further activate the oyster calcium powder. The composite bacterial agent includes spores, yeasts, lactic acid bacteria and acetic acid bacteria, and the ratio of spores, yeasts, lactic acid bacteria and acetic acid bacteria is 2:3:2:1;

[0020] During the preparation of the composite bacterial agent, spore-forming bacteria, yeast, lactic acid bacteria and acetic acid bacteria after the concentration of live bacteria is determined are placed into the mixing equipment according to the proportion, and the mixing temperature is 20-25°C.

[0021] As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, the fertilizer particles prepared in S5 are fed into a rotary dryer with a drying temperature of 80-100°C. The rotary dryer dries the fertilizer particles and reduces the moisture content of the fertilizer particles to 10-12%. Then, a cooling device and a screening device are used to screen and cool the fertilizer particles. The cooled fertilizer particles are transported to the inside of the packaging device for sealed packaging.

[0022] As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, when the cooling equipment cools the fertilizer particles, cold air circulates inside the cooling equipment, and the cold air contacts the surface of the fertilizer particles during the circulation process to cool the fertilizer particles.

[0023] As a preferred method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, when the screening equipment screens the fertilizer particles, the cooled fertilizer particles are poured into the screening equipment, and multiple layers of screens with different apertures are provided inside the screening equipment to screen out fertilizer particles that do not meet the particle size requirements.

[0024] As a preferred preparation method of a composite organic fertilizer based on seaweed residue and oyster calcium of the present invention, when the packaging equipment packages the fertilizer particles, the screened qualified fertilizer particles are first collected, and then the collected fertilizer particles are transported to a filling mechanism, and the filling mechanism fills the fertilizer particles into a sterile container. During the filling process, the fertilizer particles are measured, and the filling is stopped when the preset measurement value is reached. The conveying mechanism transports the filled fertilizer particles and the sterile container to a sealing mechanism, and the sealing mechanism seals the sterile container.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The oyster calcium powder of the present invention is rich in calcium carbonate, which can effectively neutralize acidic soil and adjust the soil pH to a range suitable for crop growth. The organic matter in the seaweed residue and humic acid work synergistically to further improve the soil aggregate structure, enhance air permeability and permeability. The microporous structure of the oyster calcium powder is combined with the water retention capacity of humic acid to significantly improve the soil's water and fertilizer retention capacity and reduce nutrient loss. The porous structure of the oyster calcium powder can adsorb heavy metal ions in the soil, reduce their bioavailability, and reduce the risk of crop pollution. The seaweed residue provides nitrogen, phosphorus, potassium and trace elements, and releases natural plant hormones to promote crop root development and stress resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION

[0028] Example 1

[0029] A composite organic fertilizer based on seaweed residue and oyster calcium comprises the following raw materials in parts by weight:

[0030] 40-50 parts of seaweed residue, 20-30 parts of oyster calcium powder, 1-2 parts of composting agent, 5-10 parts of nitrogen source supplement, 5-8 parts of humic acid, and 1-2 parts of trace element additives.

[0031] Oyster calcium powder is rich in calcium carbonate, which can effectively neutralize acidic soil and adjust the soil pH to a range suitable for crop growth. The organic matter in seaweed residue works synergistically with humic acid to further improve the soil aggregate structure, enhance air permeability and permeability. The microporous structure of oyster calcium powder combined with the water retention capacity of humic acid significantly improves the soil's water and fertilizer retention capacity and reduces nutrient loss. The porous structure of oyster calcium powder can adsorb heavy metal ions in the soil, reduce their bioavailability, and reduce the risk of crop pollution. Seaweed residue provides nitrogen, phosphorus, potassium and trace elements, and releases natural plant hormones to promote crop root development and stress resistance.

[0032] Oyster calcium powder supplements calcium, magnesium and other medium-amount elements, and can work with nitrogen source supplements to balance nutrient ratios to meet the needs of crops at different growth stages. Composting agents accelerate the decomposition of organic matter, release nitrogen and phosphorus nutrients, and improve fertilizer utilization. Trace element additives supplement boron, iron, and zinc to prevent crop deficiencies and improve fruit quality. The organic combination of seaweed residue and humic acid allows for the slow release of nutrients and prolongs fertilizer effectiveness. Alginic acid can activate the crop immune system and reduce pests and diseases. The calcium element in oyster calcium strengthens cell walls and improves crop resistance to lodging and drought.

[0033] Seaweed residue utilizes marine algae waste, and oyster calcium raw materials are taken from oyster shells, which reduces marine garbage pollution and conforms to the concept of circular economy. The composting agent accelerates the degradation of organic waste and reduces the nitrogen loss of traditional composting. The acid-regulating function of oyster calcium is combined with the organic matter of seaweed residue to form a stable granular structure, avoiding the limitations of a single raw material. The composting agent and humic acid jointly promote the diversity of microbial communities and enhance the stability of soil ecosystems.

[0034] Example 2

[0035] See also Figure 1 A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium comprises the following steps:

[0036] S1. Raw material pretreatment: seaweed residue and oyster calcium powder are pretreated. EM bacteria or Bacillus subtilis are used as composting agents, urea or ammonium sulfate is used as nitrogen source supplement, natural humic acid or fulvic acid is used as humic acid, and one or more of chelated boron, molybdenum or manganese is used as trace element additives;

[0037] S2. Mix the raw materials: seaweed residue, oyster calcium powder, composting agent and nitrogen source supplement according to the proportion of parts by weight, using a double-shaft paddle mixer for 10-15 minutes to ensure uniformity;

[0038] S3, composting fermentation, pre-treating the mixed fertilizer raw materials, adjusting the moisture content to 50-60%, and then piling them in a fermentation tank. The height of the fertilizer pile is 1.5-2 meters and the width is 2-3 meters. The temperature of the fermentation pile is first raised to 50-65℃ and maintained for 48-72 hours to kill pathogens, then lowered to 45-50℃ and fermented for 15-20 days. During the fermentation process, the pile is turned every 3 days to ensure oxygen supply and uniform fermentation;

[0039] S4. Adding functional ingredients: adding humic acid and trace element additives to the composted raw materials according to the proportion of parts by weight, and mixing them evenly using a double-shaft paddle mixer;

[0040] S5, granulation and molding, feeding the mixed material into a drum granulator, adjusting the speed of the drum granulator to 15-25 rpm, the granulation time to 30-45 minutes, and the particle size to 2-4 mm to prepare fertilizer granules.

[0041] 7. Furthermore, when pre-treating the seaweed residue in S1, impurities on the seaweed residue are first cleaned using a cleaning device, and then vacuum extrusion dehydration is performed. After dehydration, the seaweed residue is dried using a drying device. After drying, the seaweed residue is crushed using a grinder to control the particle size of the seaweed residue to 1-2 mm. The crushed seaweed residue is mixed with an acetic acid-sodium acetate buffer solution with a pH of 5.0;

[0042] adding cellulase to the seaweed residue in a ratio of 100:2, extracting at 55°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 4.2 after the enzyme inactivation is completed; adding pectinase to the seaweed residue in a ratio of 100:1, extracting at 50°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 6.0 after the enzyme inactivation is completed; adding fibrinase to the seaweed residue in a ratio of 100:1, extracting at 55°C for 48 hours, and then inactivating the enzyme at 100°C for 5 minutes, to decompose the cellulose, pectin and protein in the seaweed residue, so that the subsequent composting effect is better;

[0043] During enzymatic hydrolysis processing, a multifunctional composite enzymatic hydrolysis reaction system is used. The multifunctional composite enzymatic hydrolysis reaction system includes a reaction tank system, a temperature control system, a stirring system, a pH adjustment system and an enzyme liquid adding system. The enzyme liquid adding system adds cellulase, pectinase and fibrinase into the reaction tank system through a multi-channel metering pump. The temperature control system controls the temperature inside the reaction tank system. The stirring system stirs and mixes the enzymes and raw materials inside the reaction tank system. During the stirring and mixing process, the pH adjustment system adjusts the pH value inside the reaction tank system. The temperature control system heats the raw materials and enzymes inside the reaction tank system through an electric heating jacket.

[0044] 8. Furthermore, when pre-treating the oyster calcium powder in S1, the oyster shells are thoroughly cleaned with clean water, and then the oyster shells are placed in a well-ventilated place for drying. The dried oyster shells are placed in a crushing and grinding device, first crushed into oyster shell fragments, and then ground into a fine powder;

[0045] The crushing and grinding equipment includes a feeding system, a crushing system, a grinding system, and a discharging and collecting system. The feeding system transports the oyster shells to the crushing system through a vibrating feeder. The crushing system is a hammer crusher, which crushes the oyster shells into fragments. The oyster fragments enter the grinding system. The grinding system is a ball mill. The ball mill grinds the oyster fragments through the collision and friction between the steel balls installed in the cylinder and the oyster fragments. The ground oyster shell powder enters the discharging and collecting system. The discharging and collecting system is equipped with multi-stage screening equipment to screen the oyster shell powder. The qualified oyster shell powder enters the finished product collection container, and the unqualified oyster powder flows back to the grinding system for further grinding.

[0046] Furthermore, during the operation of the twin-shaft paddle mixers in S2 and S4, different types of raw materials are added to the feed port of the mixer according to a predetermined ratio. After the addition is completed, the twin-shaft paddle mixer is started. At this time, the two stirring shafts inside the twin-shaft paddle mixer begin to rotate to drive the paddles to work synchronously, so that the material is fully stirred in the space between the two shafts. During the mixing process, the paddles cause the material to be subjected to axial thrust while also being subjected to radial dispersion force to break up the formed clumps and promote uniform distribution between the components. After completing the predetermined mixing time, the machine is stopped and the electric discharge valve is opened to discharge the raw materials inside the twin-shaft paddle mixer.

[0047] Furthermore, during the fermentation process, 2-5 parts of bentonite, 1-2 parts of chitin, and 1-2 parts of a composite bacterial agent are added to the fertilizer raw materials in S3 and evenly mixed with the fertilizer raw materials to further activate the oyster calcium powder. The composite bacterial agent includes spores, yeasts, lactic acid bacteria, and acetic acid bacteria. The ratio of spores, yeasts, lactic acid bacteria, and acetic acid bacteria is 2:3:2:1.

[0048] During the preparation of the composite bacterial agent, spore-forming bacteria, yeast, lactic acid bacteria and acetic acid bacteria after the concentration of live bacteria is determined are placed into the mixing equipment according to the proportion, and the mixing temperature is 20-25°C.

[0049] Furthermore, the fertilizer granules prepared in S5 are fed into a rotary dryer at a drying temperature of 80-100° C. The rotary dryer dries the fertilizer granules and reduces the moisture content of the fertilizer granules to 10-12%. The fertilizer granules are then screened and cooled using a cooling device and a screening device. The cooled fertilizer granules are transported to a packaging device for sealed packaging.

[0050] Furthermore, when the cooling device cools the fertilizer particles, cold air circulates inside the cooling device, and during the circulation of the cold air, the cold air contacts the surface of the fertilizer particles, thereby cooling the fertilizer particles.

[0051] Furthermore, when the screening equipment screens the fertilizer particles, the cooled fertilizer particles are poured into the screening equipment. The screening equipment is provided with multiple layers of screens with different apertures to screen out the fertilizer particles that do not meet the particle size requirements.

[0052] Furthermore, when the packaging equipment packages the fertilizer granules, it first collects the qualified fertilizer granules that have been screened out, and then transports the collected fertilizer granules to the filling mechanism. The filling mechanism fills the fertilizer granules into the sterile container. During the filling process, the fertilizer granules are measured. When the preset measurement value is reached, the filling is stopped. The conveying mechanism transports the filled fertilizer granules and the sterile container to the sealing mechanism, and the sealing mechanism seals the sterile container.

[0053] Through graded enzymatic hydrolysis of cellulase, pectinase and fibrinase, combined with segmented pH adjustment, the cellulose, pectin and protein in the seaweed residue can be efficiently decomposed, the encapsulated nitrogen, phosphorus, potassium and trace elements can be released, and their bioavailability can be significantly improved. The oyster shells are crushed into fine powder to increase the specific surface area and accelerate the release of medium-sized elements such as calcium and magnesium. Its porous structure can adsorb ammonia produced during the fermentation process and reduce nitrogen loss. Spores, yeasts, lactic acid bacteria and acetic acid bacteria are added in the composting stage to enhance the decomposition and humification of organic matter. Spores are resistant to high temperatures and decompose cellulose. Lactic acid bacteria and acetic acid bacteria regulate pH to inhibit pathogens. Yeasts promote carbon source utilization, significantly shortening the composting cycle and improving the degree of maturity.

[0054] Adding bentonite improves the compost structure and increases porosity. Chitosan reduces interference from foreign bacteria through its antibacterial properties and improves compost stability. The fermentation temperature is controlled in stages and the compost is turned every three days to ensure oxygen supply and uniform fermentation, effectively killing pathogens and weed seeds and promoting humic acid production. Natural humic acid combines with chelated boron, molybdenum, and manganese. The water and fertilizer retention capacity of humic acid and the anti-soil fixation properties of chelated trace elements significantly improve the efficiency of crop nutrient absorption.

[0055] The calcium carbonate component of oyster calcium neutralizes acidic soil, and its porous structure absorbs heavy metals to reduce the risk of crop pollution. Calcium and magnesium supplements strengthen crop cell walls, improving lodging resistance and drought resistance. A double-shaft paddle mixer is used to ensure uniform mixing of raw materials, and a drum granulator controls the particle size to 2-4mm to avoid clumping and improve field application efficiency.

[0056] The rotary dryer reduces the moisture content to 10-12%, extending the storage period. Cold air circulation cooling and multi-layer screen screening remove unqualified particles, ensuring product particle size consistency and aseptic filling and sealed packaging to meet commercialization requirements. Seaweed residue is taken from marine algae processing waste, and oyster shell powder is derived from marine aquaculture waste, reducing resource waste and complying with the concept of a circular economy. Enzymatic pretreatment replaces chemical treatment, and compound microbial agents reduce dependence on exogenous fertilizers. No chemical synthetic additives are used throughout the process, achieving green production.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite organic fertilizer based on seaweed residue and oyster calcium, characterized in that: The composition comprises the following raw materials in parts by weight: 40-50 parts of seaweed residue, 20-30 parts of oyster calcium powder, 1-2 parts of composting agent, 5-10 parts of nitrogen source supplement, 5-8 parts of humic acid, and 1-2 parts of trace element additives.

2. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium, applicable to the composite organic fertilizer based on seaweed residue and oyster calcium according to claim 1, characterized in that: The following steps are involved: S1. Raw material pretreatment: seaweed residue and oyster calcium powder are pretreated. EM bacteria or Bacillus subtilis are used as composting agents, urea or ammonium sulfate is used as nitrogen source supplement, natural humic acid or fulvic acid is used as humic acid, and one or more of chelated boron, molybdenum or manganese is used as trace element additives; S2. Mix the raw materials: seaweed residue, oyster calcium powder, composting agent and nitrogen source supplement according to the proportion of parts by weight, using a double-shaft paddle mixer for 10-15 minutes to ensure uniformity; S3, composting fermentation, pre-treating the mixed fertilizer raw materials, adjusting the moisture content to 50-60%, and then piling them in a fermentation tank. The height of the fertilizer pile is 1.5-2 meters and the width is 2-3 meters. The temperature of the fermentation pile is first raised to 50-65℃ and maintained for 48-72 hours to kill pathogens, then lowered to 45-50℃ and fermented for 15-20 days. During the fermentation process, the pile is turned every 3 days to ensure oxygen supply and uniform fermentation; S4. Adding functional ingredients: adding humic acid and trace element additives to the composted raw materials according to the proportion of parts by weight, and mixing them evenly using a twin-shaft paddle mixer; S5, granulation and molding, feeding the mixed material into a drum granulator, adjusting the speed of the drum granulator to 15-25 rpm, the granulation time to 30-45 minutes, and the particle size to 2-4 mm to prepare fertilizer granules.

3. A method for preparing a composite organic fertilizer based on seaweed slag and oyster calcium according to claim 2, characterized in that: When pre-treating the seaweed residue in S1, impurities on the seaweed residue are first cleaned using a cleaning device, and then vacuum extrusion dehydration is performed. After dehydration, the seaweed residue is dried using a drying device. After drying, the seaweed residue is crushed using a crusher to control the particle size of the seaweed residue to 1-2 mm. The crushed seaweed residue is mixed with an acetic acid-sodium acetate buffer solution with a pH of 5.0; adding cellulase to the seaweed residue in a ratio of 100:2, extracting at 55°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 4.2 after the enzyme inactivation is completed; adding pectinase to the seaweed residue in a ratio of 100:1, extracting at 50°C for 72 hours, then inactivating the enzyme at 100°C for 5 minutes, and adjusting the pH to 6.0 after the enzyme inactivation is completed; adding fibrinase to the seaweed residue in a ratio of 100:1, extracting at 55°C for 48 hours, and then inactivating the enzyme at 100°C for 5 minutes, to decompose the cellulose, pectin and protein in the seaweed residue, so that the subsequent composting effect is better; During enzymatic hydrolysis processing, a multifunctional composite enzymatic hydrolysis reaction system is used. The multifunctional composite enzymatic hydrolysis reaction system includes a reaction tank system, a temperature control system, a stirring system, a pH adjustment system and an enzyme liquid adding system. The enzyme liquid adding system adds cellulase, pectinase and fibrinase into the reaction tank system through a multi-channel metering pump. The temperature control system controls the temperature inside the reaction tank system. The stirring system stirs and mixes the enzymes and raw materials inside the reaction tank system. During the stirring and mixing process, the pH adjustment system adjusts the pH value inside the reaction tank system. The temperature control system heats the raw materials and enzymes inside the reaction tank system through an electric heating jacket.

4. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 3, characterized in that: When pre-treating the oyster calcium powder in S1, the oyster shells are thoroughly cleaned with clean water, and then the oyster shells are placed in a well-ventilated place for drying, and the dried oyster shells are placed in a crushing and grinding device, first crushed into oyster shell fragments, and then ground into a fine powder; The crushing and grinding equipment includes a feeding system, a crushing system, a grinding system, and a discharging and collecting system. The feeding system transports the oyster shells to the crushing system through a vibrating feeder. The crushing system is a hammer crusher, which crushes the oyster shells into fragments. The oyster fragments enter the grinding system. The grinding system is a ball mill. The ball mill grinds the oyster fragments through the collision and friction between the steel balls installed in the cylinder and the oyster fragments. The ground oyster shell powder enters the discharging and collecting system. The discharging and collecting system is equipped with multi-stage screening equipment to screen the oyster shell powder. The qualified oyster shell powder enters the finished product collection container, and the unqualified oyster powder flows back to the grinding system for further grinding.

5. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 4, characterized in that: During the operation of the twin-shaft paddle mixers in S2 and S4, different types of raw materials are added to the feed port of the mixer according to a predetermined ratio. After the addition is completed, the twin-shaft paddle mixer is started. At this time, the two stirring shafts inside the twin-shaft paddle mixer start to rotate to drive the paddles to work synchronously, so that the material is fully stirred in the space between the two shafts. During the mixing process, the paddles cause the material to be subjected to axial thrust while also being subjected to radial dispersion force to break up the formed clumps and promote uniform distribution among the components. After the predetermined mixing time is completed, the machine is stopped and the electric discharge valve is opened to discharge the raw materials inside the twin-shaft paddle mixer.

6. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 5, characterized in that: During the fermentation process, 2-5 parts of bentonite, 1-2 parts of chitin, and 1-2 parts of a composite bacterial agent are added to the fertilizer raw materials in S3 and evenly mixed with the fertilizer raw materials to further activate the oyster calcium powder. The composite bacterial agent includes spores, yeasts, lactic acid bacteria, and acetic acid bacteria. The ratio of spores, yeasts, lactic acid bacteria, and acetic acid bacteria is 2:3:2:

1. During the preparation of the composite bacterial agent, spore-forming bacteria, yeast, lactic acid bacteria and acetic acid bacteria after the concentration of live bacteria is determined are placed into the mixing equipment according to the proportion, and the mixing temperature is 20-25°C.

7. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 6, characterized in that: The fertilizer granules prepared in S5 are fed into a rotary dryer at a drying temperature of 80-100° C. The rotary dryer dries the fertilizer granules and reduces the moisture content of the fertilizer granules to 10-12%. The fertilizer granules are then screened and cooled using a cooling device and a screening device. The cooled fertilizer granules are then transported to a packaging device for sealed packaging.

8. A method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 7, characterized in that: When the cooling device cools the fertilizer particles, cold air circulates inside the cooling device, and the cold air contacts the surface of the fertilizer particles during the circulation process, thereby cooling the fertilizer particles.

9. The method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 8, wherein: When the screening device is screening the fertilizer particles, the cooled fertilizer particles are poured into the screening device. The screening device is internally provided with multiple layers of screens with different apertures to screen out the fertilizer particles that do not meet the particle size requirements.

10. The method for preparing a composite organic fertilizer based on seaweed residue and oyster calcium according to claim 9, characterized in that: When the packaging equipment packages the fertilizer granules, the qualified fertilizer granules screened out are first collected, and then the collected fertilizer granules are transported to the filling mechanism. The filling mechanism fills the fertilizer granules into the sterile container. The fertilizer granules are measured during the filling process. When the preset measurement value is reached, the filling is stopped. The conveying mechanism transports the filled fertilizer granules and the sterile container to the sealing mechanism, and the sealing mechanism seals the sterile container.

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