Organic fertilizer prepared from caragana and preparation method thereof

Abstract

This invention discloses an organic fertilizer prepared using *Caragana korshinskii* and its preparation method, belonging to the field of organic fertilizer preparation technology. It aims to solve the problems of phenolic and tannin secondary metabolites in *Caragana korshinskii* inhibiting fermentation, leading to initiation difficulties and low fertilizer bioactivity. The preparation method involves drying and pulverizing *Caragana korshinskii*, then extracting it with water, separating the solid and liquid to obtain an extract and an extract residue. After adjusting the pH of the extract, a transformation agent composed of *Saccharomyces cerevisiae* and *Lactobacillus plantarum* is inoculated for anaerobic fermentation to obtain a fermentation-enhancing liquid. The extract residue is mixed with livestock and poultry manure, and the carbon-to-nitrogen ratio is adjusted. A cellulose-degrading agent is then inoculated for aerobic fermentation to obtain a mature substrate. Finally, the mature substrate is dried, pulverized, sprayed with the fermentation-enhancing liquid, and incubated to activate it, thus producing *Caragana korshinskii* organic fertilizer. The organic fertilizer prepared by this method can be used to improve soil and promote crop growth.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer preparation technology. More specifically, this invention relates to an organic fertilizer prepared using Caragana korshinskii and its preparation method. Background Technology

[0002] Caragana korshinskii, a legume rich in organic matter and nutrients such as nitrogen and potassium, has high development potential in the fields of ecological restoration and bio-fertilizers. Currently, the common method for preparing organic fertilizer from Caragana korshinskii is to directly crush it and mix it with livestock and poultry manure for composting. However, in practical applications, this technical route faces significant fermentation obstacles.

[0003] Because *Caragana korshinskii* plants contain a certain amount of secondary metabolites such as phenols and tannins, these substances can damage the cell membrane structure of microorganisms or chelate metal ions when they come into contact with them, inhibiting the normal metabolic activities of fermenting microorganisms. In the early stages of composting, the presence of these inhibitors often leads to difficulties in initiating fermentation, slow temperature rise in the compost pile, and difficulty in achieving complete decomposition even with extended fermentation periods. Furthermore, conventional composting processes have low conversion efficiency for the potential active ingredients in *Caragana korshinskii* raw materials, and the resulting organic fertilizer products, after being applied to the soil, do not have an stable effect on promoting crop growth, and their biological activity needs to be improved.

[0004] To reduce the content of inhibitors such as phenols and tannins in *Caragana korshinskii*, some studies have attempted pretreatment through water washing or prolonged open-air leaching. However, these methods consume large amounts of water and result in the loss of soluble organic nutrients, making them counterproductive. Attempts have also been made to use chemical oxidants or acid / alkali treatments to disrupt the structure of these inhibitors. However, the introduction of chemical reagents not only increases production costs but may also cause secondary pollution and damage the natural organic components in the raw materials, introducing new uncertainties to subsequent fermentation.

[0005] Regarding fermentation processes, existing technologies for degrading lignocellulose in Caragana korshinskii mainly focus on screening for highly efficient cellulose-decomposing bacteria, but pay insufficient attention to eliminating water-soluble inhibitors in the fermentation environment. Even with inoculation with highly efficient degrading agents, if the concentrations of phenols and tannins in the fermentation system are not effectively reduced, the activity of the strains will still be significantly inhibited, leading to a prolonged fermentation cycle and uneven material maturity. Simultaneously, how to convert the underutilized small-molecule organic matter in Caragana korshinskii into bioactive metabolites is also a challenge in increasing the added value of fertilizers.

[0006] In the post-processing stage of organic fertilizer products, conventional drying and pulverizing processes can easily lead to the loss of some volatile active ingredients. Furthermore, liquid functional substances are difficult to combine stably with solid fertilizers, and problems such as the attenuation and uneven distribution of effective ingredients can easily occur during storage or application, thus limiting the overall performance of the fertilizer.

[0007] Therefore, in the process of preparing organic fertilizer from Caragana korshinskii, how to effectively eliminate the adverse effects of inhibitors such as phenols and tannins in the raw materials on fermenting microorganisms, achieve rapid start-up and stable operation of the fermentation process, and improve the bioactivity of the final product are key issues that have long been faced and need to be solved in related technical fields. Summary of the Invention

[0008] The purpose of this invention is to provide an organic fertilizer prepared using Caragana korshinskii and its preparation method, so as to at least solve the above-mentioned problems.

[0009] To achieve the objectives and other advantages of this invention, a method for preparing organic fertilizer using *Caragana korshinskii* is provided, comprising the following steps: The dried Caragana twigs are crushed to a particle size of 0.5-2 cm to obtain Caragana twig coarse powder. Then, 3-5 times the weight of water is added to the Caragana twig coarse powder, and the powder is soaked at 20℃-30℃ for 2-4 hours for extraction. The extract and the residue are obtained by solid-liquid separation. The extract is transferred to a fermenter, the pH is adjusted to 6.0-7.0, and then a transforming agent composed of brewer's yeast and Lactobacillus plantarum in a live cell ratio of 1:1 to 2:1 is inoculated. The inoculation amount of the transforming agent is 0.1%-0.5% of the mass of the extract. Anaerobic fermentation is carried out at 28℃-35℃ for 24-48 hours to obtain a fermentation-enhancing liquid. The extraction residue is mixed with livestock and poultry manure at a mass ratio of 3:1 to 5:1, and urea is added to adjust the carbon-nitrogen ratio of the mixture to 25:1 to 35:1. Then, a cellulose-degrading microbial agent composed of Bacillus subtilis and Trichoderma viride at a live bacteria ratio of 0.5:1 to 1.5:1 is inoculated. The inoculation amount of the cellulose-degrading microbial agent is 0.2%-0.6% of the total mass of the mixture. After being mixed evenly, the mixture is piled into windrows for aerobic fermentation. The fermentation temperature is controlled at 50℃-65℃, and the pile is turned over every 3-5 days. Fermentation takes 15-25 days to obtain a decomposed substrate. After drying and pulverizing the decomposed substrate, the fermentation synergist is sprayed evenly, with the amount of the fermentation synergist being 5%-15% of the mass of the decomposed substrate. Then, the substrate is kept at 35℃-40℃ for 12-24 hours to activate it, thereby obtaining activated material. The activated material is then made into Caragana korshinskii organic fertilizer.

[0010] Preferably, the step of making the activated material into Caragana korshinskii organic fertilizer includes: feeding the activated material into a disc granulator, and under the condition of disc rotation, A 1%-3% sodium alginate solution is uniformly sprayed into the tumbling activated material using a spraying device. The volume ratio of the sodium alginate solution to the fermentation synergist is 1:5 to 1:10. The atomization pressure of the spraying device is controlled at 0.2-0.4 MPa, the droplet size is 50-150 μm, and the spraying rate is controlled at 0.5%-1.5% of the total sodium alginate solution per minute relative to the mass of the activated material. Simultaneously, 1%-3% of biochar powder relative to the mass of the activated material is sprinkled in. The granulation temperature is controlled at 30℃-40℃ to obtain granules with a diameter of 2-4 mm. The granules are then immersed in a 1%-2% calcium chloride solution for 5-10 minutes to solidify. After being removed, they are washed with clean water and dried at 35℃-45℃ until the moisture content of the granules is less than 15%, resulting in Caragana korshinskii organic fertilizer granules encapsulated with the fermentation synergist.

[0011] Preferably, before feeding the activated material into the disc granulator, the process further includes a pre-coating treatment of the activated material: placing the activated material in a coating machine, spraying a calcium stearate aqueous solution with a mass concentration of 0.5%-1.5% onto the surface of the activated material under rolling conditions, wherein the spray volume of the calcium stearate aqueous solution is 2%-5% of the mass of the activated material, continuing to roll for 5-10 minutes after spraying, and then drying in a forced air at 35℃-40℃ for 10-20 minutes to form a pre-coating layer on the surface of the activated material, thereby obtaining pre-coated activated material, and then feeding the pre-coated activated material into the disc granulator to perform the granulation step.

[0012] Preferably, the extraction process specifically includes: adding 3-5 times its weight of water to the coarse powder of the *Caragana korshinskii*, then starting an ultrasonic generator to apply ultrasonic treatment to the soaking system. The ultrasonic frequency is 20-40 kHz, the ultrasonic power density is 0.3-0.8 W / ml, the treatment time is 30-60 minutes, the system temperature is controlled not to exceed 40℃ during the treatment, and after the ultrasonic treatment is completed, the system is allowed to stand and soak for 1-2 hours at 20℃-30℃ to complete the extraction process.

[0013] Preferably, the control of the system temperature not exceeding 40°C during the treatment process is achieved in the following way: a cooling jacket is set on the outer wall of the immersion container, circulating cooling water is introduced into the cooling jacket, and a temperature sensor is set in the immersion container. The temperature sensor is linked to the cooling water inlet valve. When the temperature sensor detects that the system temperature is greater than or equal to 38°C, the cooling water inlet valve is automatically adjusted to increase the cooling water flow rate until the system temperature drops below 35°C.

[0014] Preferably, before mixing the extraction residue with livestock and poultry manure, the process further includes conveying the extraction residue to a rotary drum dryer and drying it at 60°C-70°C until the moisture content is less than 20%.

[0015] Preferably, after adjusting the pH of the extract and before inoculating with the transforming agent, the method further includes adding a compound enzyme preparation at 0.05%-0.15% of the extract mass. The compound enzyme preparation is composed of pectinase, cellulase, and β-glucosidase, and is subjected to enzymatic hydrolysis at 28℃-30℃ for 2 to 4 hours. The pectinase has an activity of 30,000-50,000 U / g, the cellulase has an activity of 20,000-40,000 U / g, and the β-glucosidase has an activity of 8,000-12,000 U / g. The mass ratio of the pectinase, cellulase, and β-glucosidase is 2:1:1.

[0016] Preferably, the activation process of keeping the material at 35℃-40℃ for 12-24 hours is carried out in an insulated activation chamber. The insulated activation chamber is equipped with multiple material trays, with a vertical spacing of 15-25 cm between adjacent material trays. The material thickness on each material tray is 3-8 cm. The bottom of each material tray is a breathable mesh plate with uniform openings. An independent humidified air distribution pipe is set under each breathable mesh plate. The distribution pipe has air outlets facing the bottom of the breathable mesh plate. During the activation process, every 2-4 hours, humidified air is introduced into the bottom of the corresponding tray layer through the distribution pipe for 5-10 minutes. The temperature of the humidified air is 35℃-40℃ and the relative humidity is 85%-95%.

[0017] The present invention also provides an organic fertilizer prepared using Caragana korshinskii, which is prepared by the above-described method for preparing organic fertilizer using Caragana korshinskii.

[0018] The present invention has at least the following beneficial effects: Firstly, a complete resource utilization process for Caragana korshinskii was constructed by sequentially processing the branches, including extraction, solid-liquid separation, fermentation of the extract, aerobic fermentation of the extract residue, and activation by mixing and activating the matured substrate with the fermentation synergistic liquid. The extraction process effectively dissolves and transfers the phenols, tannins, and other secondary metabolites rich in Caragana korshinskii, which inhibit microbial metabolism, into the extract. This avoids interference from these inhibitors with the cellulose-degrading bacteria during subsequent aerobic fermentation, solving the problem of difficult fermentation initiation. The dissolved inhibitors undergo anaerobic fermentation in the extract using a conversion agent composed of Saccharomyces cerevisiae and Lactobacillus plantarum. This process converts phenols and other substances into small-molecule active metabolites, generating a fermentation synergistic liquid rich in functional components. This not only eliminates the negative impact of the inhibitors but also turns waste into treasure. The matured substrate is then activated a second time with the fermentation synergistic liquid, allowing the base fertilizer to adsorb and load the active ingredients in the synergistic liquid, significantly enhancing the bioactivity of the final product and giving it greater potential to promote crop growth.

[0019] Secondly, by atomizing sodium alginate solution and spraying it into the tumbling activated material, sodium alginate acts as a binder to form granules, while simultaneously initially coating the fermentation-enhancing liquid adsorbed in the activated material. Subsequently, it is immersed in calcium chloride solution, where sodium alginate reacts with calcium ions to form a water-insoluble calcium alginate gel network. This tightly encapsulates the active ingredients in the fermentation-enhancing liquid within the granules, creating a physical barrier. This effectively solves the problem of rapid loss of active ingredients caused by changes in external humidity or contact with water after application when the fermentation-enhancing liquid is directly sprayed onto the fertilizer surface. Simultaneously, the granulated fertilizer allows the active substances in the enhancing liquid to be continuously released into the soil as the granules slowly degrade, extending the fertilizer's effective period and achieving a uniform distribution of active ingredients within the fertilizer, avoiding localized excessively high or low concentrations.

[0020] Third, by spraying an aqueous solution of calcium stearate onto the surface of the activated material and drying it, a hydrophobic pre-coating layer is formed on the outer layer of the material particles. This pre-coating layer, as the first physical barrier, can effectively prevent water from rapidly penetrating into the material in the aqueous environment of subsequent disc granulation and calcium chloride solution solidification. This significantly reduces the dissolution loss of hydrophilic active ingredients such as live bacteria, enzymes, and small molecule organic acids in the fermentation synergistic liquid inside the activated material. It effectively solves the technical problem of a large loss of active ingredients in the aqueous phase and a significant decrease in the number of effective live bacteria and the content of metabolites in the final granular fertilizer when directly performing wet granulation. This ensures that the synergistic effect of the activation step can be retained and immobilized in the final product to the greatest extent, thus guaranteeing the core biological activity of the fertilizer.

[0021] Fourth, utilizing the cavitation effect of ultrasound in liquids, localized high temperature and pressure can be instantly generated around the coarse powder cells of *Caragana korshinskii*, forming microjets. This effectively disrupts the plant cell wall structure, accelerating the mass transfer and dissolution of secondary metabolites such as phenols and tannins, as well as nutrients such as soluble sugars and amino acids, into the aqueous phase. Compared to conventional static soaking, ultrasound-assisted extraction significantly improves dissolution efficiency and thoroughness, while shortening the extraction time. More importantly, it ensures more complete dissolution of inhibitors, reducing their residue in the extraction residue. This minimizes the potential threat of residual inhibitors to microbial activity during subsequent aerobic fermentation, creating more favorable conditions for the smooth start-up and efficient operation of the fermentation process.

[0022] Fifth, by installing a cooling jacket in the soaking container and linking it with the temperature sensor and cooling water valve, closed-loop automatic control of the extraction system temperature is achieved. When the ultrasonic cavitation effect causes the system temperature to approach the threshold of 38°C, the control system can automatically increase the cooling water flow rate to remove heat in time, ensuring that the system temperature is always maintained within a suitable range. This effectively avoids the oxidation and polymerization reaction of phenolic substances in the extract due to local overheating, which would alter its chemical properties. At the same time, it prevents high temperatures from having a potential adverse effect on the activity of subsequent fermentation strains, ensuring the stability of the extract quality and providing a material basis with suitable temperature and stable composition for subsequent conversion and fermentation processes.

[0023] Sixth, the coarse powder of Caragana korshinskii after extraction usually contains a large amount of moisture. If it is directly mixed with livestock and poultry manure, the overall moisture content of the mixture will be too high, and the gaps between the material particles will be filled with water, resulting in poor aeration. During aerobic composting, poor aeration will hinder the diffusion of oxygen into the material, easily forming anaerobic zones inside the pile, making it difficult to raise the fermentation temperature, and even producing foul odors. By drying the extraction residue to a moisture content of less than 20%, the basic moisture content of the mixture is reduced, the physical structure of the material is optimized, and the oxygen supply during the composting process is ensured. This provides a suitable environment for the growth and reproduction of aerobic microorganisms, thereby ensuring that the cellulose-degrading agent can effectively play its role, promoting rapid heating of the pile and uniform decomposition of the material.

[0024] Seventh, in addition to phenols, tannins, and other target metabolites, the extract of *Caragana korshinskii* also contains some glycosides composed of large polysaccharides such as pectin and cellulose. These substances are difficult for *Saccharomyces cerevisiae* and *Lactobacillus plantarum* to directly transport and utilize across membranes, resulting in insufficient carbon sources in the fermentation substrate that can be directly utilized by microorganisms. By adding a compound enzyme preparation composed of pectinase, cellulase, and β-glucosidase, these large polysaccharides can be enzymatically broken down into small monosaccharides or oligosaccharides that are easily absorbed and utilized by microorganisms. This not only provides a richer source of available carbon for subsequent anaerobic fermentation, promoting the rapid proliferation and metabolic activity of *Saccharomyces cerevisiae* and *Lactobacillus plantarum*, but also helps to improve the conversion efficiency of phenolic substances, thereby increasing the amount of target active metabolites generated in the fermentation synergist and enhancing the overall biological activity of the synergist.

[0025] Eighth, by spreading the material in thin layers on a tray with a breathable mesh, the contact area between the material and the air is increased, avoiding internal heat accumulation and local overheating caused by excessive material accumulation. More importantly, by periodically introducing precisely controlled humidified air from the bottom of each tray, gentle and uniform humidification and temperature regulation of the material layer are achieved, avoiding damage to the activity caused by local overheating. This ensures that all materials are in a stable and suitable temperature and humidity environment during the activation process, thereby guaranteeing the uniformity and efficiency of the activation effect.

[0026] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0028] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials described are commercially available.

[0029] Example 1: Preparation of organic fertilizer S1 using Caragana korshinskii.

[0030] Caragana korshinskii branches were harvested from Minqin County, Gansu Province. After harvesting, they were naturally air-dried until the moisture content was below 15%. The branches were then pulverized and sieved to obtain coarse powder with a particle size of 0.5-2 cm. 100 kg of this coarse powder was placed in a stainless steel soaking tank with 400 kg of tap water and allowed to stand at 25°C for 3 hours for extraction. After soaking, solid-liquid separation was performed using a vibrating screen to obtain the extract and extract residue. The extract was transferred to a fermentation tank, and the pH was adjusted to 6.2. A transformation agent composed of *Saccharomyces cerevisiae* and *Lactobacillus plantarum* at a live bacteria ratio of 1.5:1 was then inoculated at 0.3% of the extract mass. Anaerobic fermentation was carried out at 30°C for 36 hours to obtain a fermentation-enhancing liquid. The extract residue was then transferred to a drum dryer and dried at 65°C until the moisture content reached 18%, yielding dry-basis extract residue. The dry base leachate residue was mixed with fresh cow manure (65% moisture content) at a mass ratio of 3:1. Urea was added to adjust the carbon-to-nitrogen ratio to 30:1. Then, a cellulose-degrading microbial agent, composed of Bacillus subtilis and Trichoderma viride at a live bacteria ratio of 1:1, was inoculated at a rate of 0.4% of the total mass of the mixture. After thorough mixing, the mixture was piled into windrows for aerobic fermentation. During composting, the temperature dynamically changed. In the initial mesophilic stage (30-40℃), the microbial inoculum proliferated rapidly. Subsequently, the pile naturally heated up to a high-temperature stage (55-60℃), where the microbial inoculum continued to ferment. The pile was turned over every 4 days for 20 days to obtain mature compost. The mature compost was dried at 60℃ until the moisture content was below 12%, then pulverized through a 40-mesh sieve. The fermentation-enhancing liquid was sprayed evenly at a rate of 10% of the mass of the mature compost, and then activated in a heat-insulated activation chamber. The insulated activation chamber contains multiple layers of material trays, with a vertical spacing of 20 cm between adjacent trays. Each layer of material is 5 cm thick, and the bottom of the trays is a perforated breathable mesh. Each layer of mesh has an independent humidified air distribution pipe underneath. During the activation process, every 3 hours, humidified air is introduced into the bottom of the corresponding tray layer for 8 minutes through the distribution pipe. The temperature of the humidified air is 38°C, and the relative humidity is 90%. After being kept in the insulated activation chamber for 18 hours, the activated material is obtained. The activated material was fed into a disc granulator. Under the condition of disc rotation, a 2% sodium alginate solution (volume ratio of 1:8 to the above-mentioned fermentation synergist) was evenly sprayed into the tumbling activated material through a spraying device. The atomization pressure was controlled at 0.3 MPa, the atomized droplet size was 50-150 μm, and the spraying rate was controlled at 1% of the total mass of sodium alginate solution sprayed per minute. At the same time, 2% of the biochar powder was sprinkled in. The granulation temperature was controlled at 35℃ to obtain granules with a diameter of 2-4 mm. The granules were then immersed in a 1.5% calcium chloride solution for 8 minutes to solidify, washed with clean water, and dried at 40℃ until the moisture content of the granules was less than 15%, resulting in Caragana korshinskii organic fertilizer granules embedded with the fermentation synergist, which was designated as sample S1.

[0031] Example 2: Preparation of organic fertilizer S2 using Caragana korshinskii.

[0032] The activated material was prepared according to the method of Example 1. Then, the activated material was placed in a coating machine, and a 1% (w / w) calcium stearate aqueous solution was sprayed onto the surface of the activated material under rolling conditions. The spray volume was 3.5% of the activated material's mass. After spraying, rolling continued for 8 minutes, followed by drying at 38°C for 15 minutes to form a pre-coated layer on the surface of the activated material, resulting in pre-coated activated material. The pre-coated activated material was then subjected to disc granulation, calcium chloride curing, washing, and drying according to the granulation steps of Example 1 to obtain Caragana korshinskii organic fertilizer granules, designated as sample S2.

[0033] Example 3: Preparation of organic fertilizer S3 using Caragana korshinskii.

[0034] Caragana korshinskii branches were harvested from Minqin County, Gansu Province. After harvesting, they were naturally air-dried until the moisture content was below 15%. The powder was then pulverized and sieved to obtain coarse powder with a particle size of 0.5-2 cm. 100 kg of this coarse powder was placed in an ultrasonic extraction tank equipped with a cooling jacket and a temperature sensor. 400 kg of tap water was added, and the ultrasonic generator was started at a frequency of 30 kHz and a power density of 0.5 W / ml for 45 minutes. During the process, when the temperature sensor detected that the system temperature reached 38℃, the cooling water inlet valve was automatically adjusted to increase the cooling water flow, causing the system temperature to drop below 35℃. After the ultrasonic treatment, the system was allowed to stand and soak at 25℃ for 1.5 hours to complete the extraction process. Subsequently, the solid-liquid separation, extraction liquid conversion fermentation, extraction residue drying, aerobic fermentation, activation, pre-coating, and granulation were carried out according to the steps in Example 2 to obtain Caragana korshinskii organic fertilizer granules, designated as sample S3.

[0035] Example 4: Preparation of organic fertilizer S4 using Caragana korshinskii.

[0036] The extract was obtained according to the method in Example 3. After adjusting the pH to 6.5, before inoculating with the transforming agent, a compound enzyme preparation was added to the extract at a mass ratio of 0.1%. This compound enzyme preparation was composed of pectinase (40,000 U / g), cellulase (30,000 U / g), and β-glucosidase (10,000 U / g) in a mass ratio of 2:1:1. The enzyme was slowly stirred at 50 rpm at 29°C for 3 hours for enzymatic hydrolysis. Then, the transforming agent was inoculated, and subsequent fermentation, activation, pre-coating, and granulation steps were performed as in Example 3 to obtain Caragana korshinskii organic fertilizer granules, designated as sample S4.

[0037] Comparative Example 1: Organic fertilizer D1 was prepared using Caragana korshinskii.

[0038] Caragana korshinskii branches were harvested from Minqin County, Gansu Province. After harvesting, they were naturally air-dried until the moisture content was below 15%. The branches were then pulverized and sieved to obtain coarse powder with a particle size of 0.5-2 cm. 100 kg of this coarse powder was mixed with 33 kg of fresh cow manure. Urea was added to adjust the carbon-to-nitrogen ratio to 30:1. The mixture was inoculated with the same cellulose-degrading bacteria as in Example 1, at an inoculation rate of 0.4% of the total mass. After thorough mixing, the mixture was piled into windrows for aerobic fermentation under the same conditions as in Example 1 (temperature 50-65℃, turning the pile every 4 days, fermentation for 20 days). After fermentation, the decomposed material was dried and pulverized. Without adding any fermentation enhancer, it was directly granulated using disc granulation (only sodium alginate solution was used as a binder) to obtain granular fertilizer, designated as sample D1.

[0039] Experimental example: The performance of samples S1, S2, S3, and S4 prepared in Examples 1-4 above, and sample D1 prepared in Comparative Example 1, was tested. The test indicators and methods are as follows: (1) Fermentation start-up time: The time (in hours) required from the start of stacking the windrows to the first time the temperature at the center of the pile reaches above 50°C during the aerobic composting process.

[0040] (2) Total phenol removal rate: The total phenol content in the raw material and the final product of *Caragana korshinskii* was determined using the Folin-Ciocalteu colorimetric method with gallic acid as the standard. The total phenol concentration was calculated by measuring the absorbance of the sample at 760 nm, and then the percentage of total phenol removed during the entire process was calculated. Total phenol removal rate (%) = [Q 初始 -Q 最终 ) / Q 初始 ] ×100%, Q 初始 =A×M 原料 Q 最终 =D×M 产品 , A represents the total phenol concentration of the raw material *Caragana korshinskii*, in mg / g. M 原料 D represents the dry weight of the raw material *Caragana korshinskii*, in grams; D represents the total phenol concentration of the final product, in mg / g; M represents the total phenol concentration of the final product. 产品 This is the dry weight of the final product, expressed in grams.

[0041] (3) Retention rate of active ingredients (only for S1, S2, and D1): For S1, the lactic acid content in the activated material before granulation is determined (using high performance liquid chromatography), and then the lactic acid content in the final product S1 is determined to calculate the retention rate. For S2, the lactic acid content in the activated material before pre-coating treatment is determined, and then the lactic acid content in the final product S2 is determined to calculate the retention rate. For D1, the lactic acid content in the composted material is determined, and then the lactic acid content in the final product D1 is determined to calculate the retention rate. Active ingredient retention rate = final product lactic acid content / lactic acid content of material before granulation (or composted material) × 100%.

[0042] (4) Particle disintegration time: Take 10 particle samples, place them in a beaker containing 100ml of deionized water, let them stand at room temperature, and record the time (minutes) required for the particles to completely disintegrate or disperse. Take the average value.

[0043] (5) Viable count: The effective viable count of Lactobacillus plantarum in the final particles was determined by the MRS plate counting method, and the results were expressed as CFU / g.

[0044] (6) Seed germination index: Take the final particle sample and add deionized water at a ratio of 1:10 (mass ratio), shake and extract for 1 hour, and filter to obtain the extract. Place filter paper in a petri dish, add 5 ml of extract, and evenly place 20 Chinese cabbage seeds. Incubate in the dark at 25℃ for 48 hours, count the germination rate and measure the root length, and calculate the germination index (GI) = (treatment germination rate × treatment root length) / (control germination rate × control root length) × 100%. The control is deionized water.

[0045] (7) Continuous dissolution rate: Take 10g of particle sample and place it in 200ml of pH 7.0 phosphate buffer. Shake at 100 rpm at 25℃. Take samples at 0.5, 2, 8 and 24 hours respectively, and determine the lactic acid content in the dissolution solution. Calculate the cumulative dissolution rate (dissolution amount at each time point / total lactic acid content of particles × 100%).

[0046] The test results are shown in Table 1.

[0047] Table 1 Performance test results of each embodiment and comparative example In the table, "-" indicates that the data was not tested. The results in Table 1 show that: Regarding fermentation start-up time, Examples S1 and S2 had a start-up time of 38 hours, S3 and S4 were further shortened to 32 hours, while Comparative Example D1 was as long as 72 hours. This indicates that the present invention effectively removes inhibitors from Caragana korshinskii through extraction treatment, enabling rapid aerobic fermentation to start. The start-up time was further shortened after ultrasonic-assisted extraction in S3, confirming the effect of ultrasonic treatment in making the inhibitors dissolve more thoroughly.

[0048] Regarding the total phenol removal rate, Examples S1 and S2 achieved over 86%, and Examples S3 and S4 achieved over 92%, while Comparative Example D1 only achieved 62.5%. This indicates that the impregnation and subsequent conversion processes of the present invention can effectively remove phenolic inhibitors from Caragana korshinskii. The higher removal rates of Examples S3 and S4 verify the promoting effect of ultrasonic-assisted impregnation and enzymatic hydrolysis on the removal of phenolic substances.

[0049] The active ingredient retention data demonstrates the significant effect of pre-coating treatment. S1, without pre-coating, had an active ingredient retention rate of 62.4%, meaning nearly 38% was lost during granulation and solidification. In contrast, S2, after using calcium stearate pre-coating, achieved a retention rate of 81.7%, indicating that the pre-coating layer effectively reduced the leaching and loss of active ingredients in the aqueous environment. Comparative example D1 had a retention rate of only 45.2%, indicating that conventional compost granulation resulted in even more severe losses.

[0050] The particle disintegration time reflects the stability of the encapsulation layer. The disintegration time of S1 was 168 minutes, while that of S2-S4 was extended to more than 190 minutes, indicating that the pre-coating and calcium alginate encapsulation formed a more stable bilayer encapsulation structure. The comparative disintegration time was shorter (145 minutes), indicating a weaker sustained-release capacity.

[0051] The viable cell count results showed that S1 was 3.2 × 10⁻⁶. 8 CFU / g, S2 increased to 5.8×10 8 CFU / g, S3 is 6.1×10 8 CFU / g, S4 reached 7.3×10 8 CFU / g, while comparative example D1 showed almost no viable bacteria (2×10⁻⁶). 6 (CFU / g). This result indicates that ultrasonic-assisted extraction removes inhibitors more thoroughly, providing a high-quality substrate for subsequent fermentation; enzymatic hydrolysis increases available carbon sources and promotes cell proliferation; and pre-coating treatment reduces viable cell loss during granulation, allowing more viable cells to be retained in the final product.

[0052] Germination index is a key indicator for evaluating fertilizer maturity and phytotoxicity. The germination indices of Examples S1-S4 were all above 91%, with S4 reaching 97.2%, significantly higher than the 68.7% of Comparative Example D1. This indicates that the organic fertilizer prepared by this invention is fully decomposed, has no phytotoxicity, and, due to the presence of active ingredients from the fermentation synergistic liquid, promotes seed germination and root growth. The progressively increasing germination index also confirms the synergistic effect of the various technical features.

[0053] The continuous dissolution rate test results visually demonstrate the sustained-release effect of the encapsulation. S1 showed a dissolution rate of 18.6% at 0.5 hours, 35.2% at 2 hours, 67.5% at 8 hours, and 92.8% at 24 hours, exhibiting a gradual release characteristic. The dissolution rates of S2-S4 further slowed down, with the dissolution rate dropping below 10% at 0.5 hours and the cumulative dissolution rate controlled at 75-76% after 24 hours, indicating that the pre-coating and calcium alginate double-layer encapsulation structure effectively delayed the release of the active ingredient. Comparative example D1 dissolved extremely rapidly, reaching 35.8% at 0.5 hours, 86.7% at 8 hours, and almost completely released (97.3%) after 24 hours, showing a poor sustained-release effect.

[0054] Regarding organic matter content, the organic matter contents of Examples S1 to S4 were 44.5%, 45.8%, 46.7%, and 47.2%, respectively, all higher than the 38.2% of Comparative Example D1. This indicates that the present invention effectively removed secondary metabolites such as phenols and tannins that inhibit microbial metabolism from Caragana korshinskii through extraction pretreatment, allowing the microbial activity in the aerobic fermentation stage to be fully utilized, promoting the degradation and transformation of lignocellulose substances. Simultaneously, the refilling and activation of the fermentation synergistic liquid replenished the product with active organic components, thereby improving the organic matter retention level of the final product. The further increase in organic matter content in S3 and S4 is closely related to the more thorough removal of inhibitors and higher substrate utilization rate achieved through ultrasonic-assisted extraction and compound enzyme hydrolysis treatment.

[0055] Regarding humic acid content, the humic acid contents of Examples S1 to S4 were 14.3%, 15.1%, 15.6%, and 15.8%, respectively, while that of Comparative Example D1 was only 9.2%. Humic acid is an important indicator of the degree of compost maturity, and its content directly reflects the quality of organic fertilizer. This invention promotes the efficient conversion of organic materials into humus by aerobic fermentation of the extraction residue and livestock manure, while simultaneously anaerobic fermentation of the extract with a transforming microbial agent followed by backfill activation. The further increase in humic acid content in S3 and S4 indicates that ultrasonic-assisted extraction and compound enzyme hydrolysis not only reduce the interference of inhibitors on fermenting microorganisms but also increase the amount of small molecule substrates available for microbial utilization, which is beneficial to the humification process.

[0056] Regarding lignin removal rates, the lignin removal rates of Examples S1 to S4 were 66.0%, 68.5%, 70.2%, and 72.1%, respectively, all significantly higher than the 48.5% of Comparative Example D1. Lignin is a structural component in the cell wall of *Caragana korshinskii* that is difficult to degrade, and its removal rate reflects the effect of the cellulose-degrading bacteria in the aerobic fermentation process. This invention removes fermentation inhibitors in advance through extraction, creating a favorable environment for the metabolism of cellulose-degrading bacteria during the aerobic fermentation stage, and significantly improving the lignin degradation efficiency. The lignin removal rates of S3 and S4 further increased, verifying that ultrasonic-assisted extraction resulted in more thorough dissolution of inhibitors, and that the compound enzyme hydrolysis treatment enriched the available carbon source of the fermentation system, thereby further improving the degradation efficiency of lignocellulose.

[0057] In summary, the embodiments of the present invention are significantly superior to the comparative examples in terms of fermentation initiation, inhibitor removal, active ingredient retention, viable cell count, germination promotion, slow-release performance, organic matter retention, humic acid accumulation, and lignin degradation.

[0058] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the organic fertilizer prepared using *Caragana korshinskii* and its preparation method according to this invention will be readily apparent to those skilled in the art.

[0059] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for preparing organic fertilizer using Caragana korshinskii, characterized in that, Includes the following steps: The dried Caragana twigs are crushed to a particle size of 0.5-2 cm to obtain Caragana twig coarse powder. Then, 3-5 times the weight of water is added to the Caragana twig coarse powder, and the powder is soaked at 20℃-30℃ for 2-4 hours for extraction. The extract and the residue are obtained by solid-liquid separation. The extract is transferred to a fermenter, the pH is adjusted to 6.0-7.0, and then a transforming agent composed of brewer's yeast and Lactobacillus plantarum in a live cell ratio of 1:1 to 2:1 is inoculated. The inoculation amount of the transforming agent is 0.1%-0.5% of the mass of the extract. Anaerobic fermentation is carried out at 28℃-35℃ for 24-48 hours to obtain a fermentation-enhancing liquid. The extraction residue is mixed with livestock and poultry manure at a mass ratio of 3:1 to 5:1, and urea is added to adjust the carbon-nitrogen ratio of the mixture to 25:1 to 35:

1. Then, a cellulose-degrading microbial agent composed of Bacillus subtilis and Trichoderma viride at a live bacteria ratio of 0.5:1 to 1.5:1 is inoculated. The inoculation amount of the cellulose-degrading microbial agent is 0.2%-0.6% of the total mass of the mixture. After being mixed evenly, the mixture is piled into windrows for aerobic fermentation. The fermentation temperature is controlled at 50℃-65℃, and the pile is turned over every 3-5 days. Fermentation takes 15-25 days to obtain a decomposed substrate. After drying and pulverizing the decomposed substrate, the fermentation synergist is sprayed evenly, with the amount of the fermentation synergist being 5%-15% of the mass of the decomposed substrate. Then, the substrate is kept at 35℃-40℃ for 12-24 hours to activate it, thereby obtaining activated material. The activated material is then made into Caragana korshinskii organic fertilizer.

2. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 1, characterized in that, The steps for producing Caragana korshinskii organic fertilizer from the activated material include: feeding the activated material into a disc granulator, and granulating the material under the condition of disc rotation. A 1%-3% sodium alginate solution is uniformly sprayed into the tumbling activated material using a spraying device. The volume ratio of the sodium alginate solution to the fermentation synergist is 1:5 to 1:

10. The atomization pressure of the spraying device is controlled at 0.2-0.4 MPa, the droplet size is 50-150 μm, and the spraying rate is controlled at 0.5%-1.5% of the total sodium alginate solution per minute relative to the mass of the activated material. Simultaneously, 1%-3% of biochar powder relative to the mass of the activated material is sprinkled in. The granulation temperature is controlled at 30℃-40℃ to obtain granules with a diameter of 2-4 mm. The granules are then immersed in a 1%-2% calcium chloride solution for 5-10 minutes to solidify. After being removed, they are washed with clean water and dried at 35℃-45℃ until the moisture content of the granules is less than 15%, resulting in Caragana korshinskii organic fertilizer granules encapsulated with the fermentation synergist.

3. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 2, characterized in that, Before feeding the activated material into the disc granulator, the process includes a pre-coating treatment of the activated material: the activated material is placed in a coating machine, and a calcium stearate aqueous solution with a mass concentration of 0.5%-1.5% is sprayed onto the surface of the activated material under rolling conditions. The spray volume of the calcium stearate aqueous solution is 2%-5% of the mass of the activated material. After spraying, the material continues to roll for 5-10 minutes, and then is dried by forced air at 35℃-40℃ for 10-20 minutes to form a pre-coating layer on the surface of the activated material, thus obtaining pre-coated activated material. The pre-coated activated material is then fed into the disc granulator to perform the granulation step.

4. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 1, characterized in that, The extraction process specifically includes: adding 3-5 times the mass of water to the coarse powder of the *Caragana korshinskii*, then starting an ultrasonic generator to apply ultrasonic treatment to the soaking system. The ultrasonic frequency is 20-40 kHz, the ultrasonic power density is 0.3-0.8 W / ml, and the treatment time is 30-60 minutes. During the treatment, the system temperature is controlled not to exceed 40℃. After the ultrasonic treatment, the system is allowed to stand and soak for 1-2 hours at 20℃-30℃ to complete the extraction process.

5. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 4, characterized in that, The control of the system temperature to not exceed 40°C during the process is achieved in the following way: a cooling jacket is set on the outer wall of the immersion container, and circulating cooling water is introduced into the cooling jacket. At the same time, a temperature sensor is set in the immersion container. The temperature sensor is linked to the cooling water inlet valve. When the temperature sensor detects that the system temperature is greater than or equal to 38°C, the cooling water inlet valve is automatically adjusted to increase the cooling water flow until the system temperature drops below 35°C.

6. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 1, characterized in that, Before mixing the extraction residue with livestock and poultry manure, the process further includes conveying the extraction residue to a rotary drum dryer and drying it at 60℃-70℃ until the moisture content is less than 20%.

7. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 1, characterized in that, After adjusting the pH of the extract and before inoculating with the transforming agent, the method further includes adding a compound enzyme preparation at 0.05%-0.15% of the extract mass. The compound enzyme preparation is composed of pectinase, cellulase, and β-glucosidase. The enzyme is enzymatically hydrolyzed at 28℃-30℃ for 2 to 4 hours. The pectinase has an activity of 30,000-50,000 U / g, the cellulase has an activity of 20,000-40,000 U / g, and the β-glucosidase has an activity of 8,000-12,000 U / g. The mass ratio of the pectinase, cellulase, and β-glucosidase is 2:1:

1.

8. The method for preparing organic fertilizer using *Caragana korshinskii* as described in claim 1, characterized in that, The activation process, which involves keeping the material at 35℃-40℃ for 12-24 hours, is specifically carried out in an insulated activation chamber. This chamber contains multiple layers of material trays, with a vertical spacing of 15-25 cm between adjacent trays. Each tray has a material thickness of 3-8 cm, and the bottom of each tray has a uniformly perforated breathable mesh. Below each mesh layer is an independent humidified air distribution pipe with vents facing the bottom of the mesh. During activation, every 2-4 hours, humidified air is introduced into the bottom of the corresponding tray layer through the distribution pipe for 5-10 minutes. The temperature of the humidified air is 35℃-40℃, and the relative humidity is 85%-95%.

9. Organic fertilizer prepared using Caragana korshinskii, characterized in that, It is prepared using the method for preparing organic fertilizer from Caragana korshinskii as described in any one of claims 1-8.

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