Method for preparing nitrogen slow-release organic fertilizer by aerobic fermentation of agricultural waste

Abstract

The application discloses a method for preparing nitrogen slow-release organic fertilizer by aerobic fermentation of agricultural wastes. The method comprises the following steps: crushing and pretreating raw materials such as recycled straws, waste fungus sticks and livestock and poultry manure; mixing and proportioning the raw materials according to scientific proportions; performing aerobic fermentation for 72-144 hours by using a full-automatic production line; accurately managing the temperature, humidity and pH value in the fermentation process by an intelligent control system; and finally screening and automatically packing and stacking by a mechanical arm. The organic fertilizer prepared by the method has the significant nitrogen slow-release characteristic, and the utilization rate of the fertilizer is increased by 45% compared with traditional products, so that efficient resource utilization of the agricultural wastes is realized.

Description

Technical Field

[0001] This invention belongs to the field of agricultural waste resource utilization and fertilizer preparation technology, specifically relating to a method for preparing high-quality organic fertilizer with nitrogen slow-release function from agricultural waste through aerobic fermentation. Background Technology

[0002] With the increasing intensification of agriculture, the amount of agricultural waste such as crop straw, discarded mushroom substrate, and livestock manure is rising continuously. Improper handling not only leads to enormous resource waste but also causes serious environmental problems such as water eutrophication, soil acidification, and greenhouse gas emissions. Utilizing these wastes to produce organic fertilizer is the main way to achieve resource utilization, but existing technologies still have the following shortcomings: Firstly, traditional organic fertilizer production processes (such as windrow and trough composting) generally suffer from long fermentation cycles (30-60 days), low automation, and unstable product quality. Crucially, existing processes lack real-time and precise coordinated control of temperature, humidity, oxygen concentration, and pH within the compost pile, resulting in uneven material maturation and large batch-to-batch quality fluctuations, making it difficult to meet the requirements of modern standardized production. Secondly, existing organic fertilizers have significant deficiencies in nutrient availability. During composting, a large amount of ammonium nitrogen produced after the mineralization of organic nitrogen is lost through volatilization as ammonia (total nitrogen loss can reach 30% to 50%). Furthermore, nitrogen in traditional organic fertilizers is primarily in a fast-acting form, which hydrolyzes and leaches rapidly after being applied to the soil. This is severely misaligned with the nutrient requirements of crops (especially tea trees and fruit trees), resulting in fertilizer utilization rates generally below 40%. This not only increases agricultural costs but also exacerbates soil compaction, acidification, and agricultural non-point source pollution caused by excessive application of chemical fertilizers.

[0003] In addition, the existing production lines have a low level of automation and intelligence. The processes of raw material mixing, fermentation control, screening and packaging rely on manual labor. In particular, the packaging and palletizing process is labor-intensive and inefficient, making it difficult to meet the needs of large-scale production.

[0004] To address the aforementioned issues, existing technologies, such as the Chinese patent application with publication number CN109604777A, propose a method for preparing organic fertilizer using aerobic microbial fermentation. However, this method primarily focuses on strain selection and fails to address the problem of precise, multi-parameter synergistic control during the fermentation process, nor does it involve a systematic solution for nitrogen speciation regulation and slow-release performance improvement. Currently, no methods have been reported that organically integrate aerobic fermentation of agricultural waste with tiered environmental synergistic control, chemical conditioning of waste microbial substrates, online sensor monitoring, and automated packaging and palletizing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing nitrogen-slow-release organic fertilizer by aerobic fermentation of agricultural waste, so as to solve the problem of nutrient release in the prior art.

[0006] To achieve the above objectives, this invention provides a method for preparing nitrogen-slow-release organic fertilizer from agricultural waste through aerobic fermentation, comprising the following steps:

[0007] Raw material pretreatment: The recycled straw and waste mushroom sticks are crushed in two stages to control the particle size of the crushed material to be 3-8 mm, and then mixed with livestock and poultry manure for conditioning. Mixing and batching: The pretreated materials are fed into a high-efficiency granulation mixer. Through precise metering, the carbon-nitrogen ratio of the mixture is adjusted to (25-30):1, and the initial moisture content is controlled at 55%-65%. Aerobic fermentation and quality control: The uniformly mixed material is continuously fed into a fully automated aerobic fermentation chamber with jacket temperature control and bottom matrix aeration system for closed fermentation. The total fermentation cycle is 72-144 hours. An intelligent control system is used to construct a step-by-step collaborative control strategy based on the fermentation cycle to manage the temperature, humidity, oxygen concentration and pH value in a coordinated manner during the fermentation process. Screening and Packaging: The fermented and decomposed product is fed into a drum screen to screen out particles with a diameter of ≤5mm as nitrogen slow-release organic fertilizer. Multi-degree-of-freedom heavy-duty industrial robotic arms are used for automated weighing, sealing, packaging and palletizing.

[0008] Furthermore, in the aerobic fermentation and quality control steps, the step-by-step synergistic control strategy specifically includes: During the warming period (0-24h): the aeration rate of the bottom matrix aeration system is controlled at 0.05-0.1 m3 / (m3·min). The temperature inside the fermentation chamber is raised to 50°C-55°C at a rate of 1.5°C / h-2.5°C / h by utilizing the biological fermentation heat of the material itself, thereby promoting the large-scale reproduction of thermophilic microorganisms. High-temperature holding period (24h-96h): Maintain the temperature inside the fermentation chamber at 55°C-65°C. When the temperature exceeds 65°C, the intelligent control system will activate the jacket cooling water circulation and increase the aeration rate to 0.2 m3 / (m3·min) to cool down. At the same time, control the humidity inside the fermentation chamber to 50%-60% and maintain the pH value at 6.5-7.5 to promote the degradation of lignocellulose and convert biomass nitrogen into solid phase cell nitrogen. Cooling and composting period (96h-144h): Gradually reduce the aeration rate to 0.02-0.05 m3 / (m3·min) to allow the material temperature to drop naturally to ambient temperature, forming a humic matrix with high acidity functional group content.

[0009] Furthermore, the slow-release mechanism of the nitrogen slow-release organic fertilizer is as follows: through precise synergistic control of temperature, humidity and pH value during the high-temperature holding period, the lignocellulose in the mushroom sticks and straw is promoted to undergo directional degradation into active humic acid rich in carboxyl and phenolic hydroxyl groups. This active humic acid and ammonium nitrogen produced by the degradation of livestock and poultry manure are physically adsorbed and chemically chelated through hydrogen bonds and ionic bonds to form an organic slow-release nitrogen fixation body with a network complex structure, thereby inhibiting the rapid hydrolysis and leaching of nitrogen and achieving a fertilizer utilization rate that is more than 45% higher than that of traditional organic fertilizers.

[0010] Furthermore, in the raw material pretreatment, the waste mushroom sticks are pre-treated with chemical conditioning, and their initial pH value is adjusted to 6.0-6.5 using a dilute acid solution before being mixed with the livestock and poultry manure, in order to suppress the escape of ammonia during the premixing stage and improve the nitrogen fixation efficiency of the entire process.

[0011] Furthermore, the fully automated aerobic fermentation chamber is equipped with an online multi-point matrix sensor network. The sensor network includes infrared temperature sensors, insertable conductivity pH composite electrodes, and laser tunable diode absorption spectroscopy (TDLAS) ammonia concentration monitors that are uniformly distributed at different depths of the fermentation solid material, in order to provide real-time feedback of micro-zone fermentation status parameters to the intelligent control system.

[0012] Furthermore, the method also includes a microbial technology upgrade step: during the cooling and composting period of the aerobic fermentation, when the material temperature drops to 40-45 ℃, a compound functional microbial agent is quantitatively sprayed into the fermentation chamber. The functional microbial agent includes a mixed bacterial solution of Bacillus subtilis, Bacillus megaterium, and Bacillus megaterium. After spraying, the aerobic state is maintained for fermentation for 12-24 hours to obtain a microbial fertilizer with growth-promoting and disease-preventing functions.

[0013] Furthermore, in the screening and packaging step, the multi-degree-of-freedom heavy-duty industrial robotic arm adopts an adaptive gripping control algorithm based on machine vision positioning. Its end effector is equipped with dual-sided pneumatic grippers and vacuum suction cups to grip, move, label, and seal single bags of organic fertilizer in conjunction with the packaging line. The full cycle of automatic packaging of a single bag is stable at 10-12 seconds.

[0014] Furthermore, the organic fertilizer prepared by this method can be customized to produce a special organic fertilizer for tea trees that meets the growth needs of tea by adjusting the proportion of waste mushroom sticks in the raw materials to change the asymmetric abundance of free amino acids and humic acid in the fertilizer; or, dehydrated and conditioned domestic sludge can be introduced into the raw materials to participate in the aerobic fermentation process to produce special fertilizer for non-edible crops or landscaping.

[0015] Compared with the prior art, the present invention has the following significant advantages: High resource conversion efficiency: Through scientific ingredient ratios and a fully automated fermentation system, each ton of agricultural waste raw material can be converted into 0.28 tons of high-quality organic fertilizer.

[0016] Excellent nutrient performance: The product uses nitrogen slow-release technology, which increases fertilizer utilization by 45% compared with traditional products, effectively prolongs fertilizer effect and reduces nitrogen loss.

[0017] Highly automated production: Using fully automated production lines and robotic arms for palletizing, each bag can be packaged in just 12 seconds, greatly improving production efficiency and reducing labor costs.

[0018] Precise quality control: Equipped with an intelligent control system, the temperature, humidity and pH value during the fermentation process are monitored and precisely adjusted in real time to ensure the maturity and quality stability of each batch of products.

[0019] It has strong environmental synergy: it can process various wastes such as straw, mushroom sticks, livestock and poultry manure and even sludge on a large scale, achieving a good balance between ecological and economic benefits. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1. Overall process flow diagram for preparing nitrogen slow-release organic fertilizer according to the present invention; Figure 2. Schematic diagram of the operation process in the raw material pretreatment and scientific batching stage; Figure 3. System composition module diagram of the fully automated aerobic fermentation production line; Figure 4. Logic block diagram of parameter acquisition and feedback of intelligent quality control system; Figure 5. Comparison curve of nitrogen release rate of the product of this invention with that of traditional organic fertilizer; Figure 6 Customized production adjustment logic diagram for different crops Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0022] Example 1: Preparation of Nitrogen Slow-Release Organic Fertilizer for Tea Trees. This example demonstrates a complete process for customizing organic fertilizer for tea trees by adjusting the proportion of waste mushroom substrate to alter the asymmetric abundance of free amino acids and fulvic acid. The overall process flow is as follows: Figure 1 The six core stages are as follows: raw material recycling → S1 crushing and pretreatment → S2 scientific ingredient proportioning → S3 fully automatic fermentation → S4 intelligent parameter control → S5 sieving → S6 robotic arm automatic packaging and palletizing.

[0023] The specific operation steps and technical details are as follows: Step S1-1: Refer to Figure 2 , Figure 3 Raw material pretreatment and conditioning steps Two-stage crushing: The recycled straw and waste mushroom spawn are fed into a two-stage crusher. The first stage crushes the straw to below 20mm, and the second stage finely crushes it to a median particle diameter of 5mm.

[0024] Pre-treatment with chemical conditioning: Waste mushroom spawn and straw were recycled and crushed, and their initial pH value was measured to be 7.8. Since a high pH value easily leads to a large amount of ammonia gas escaping during the material mixing stage, this embodiment uses a 5% (w / w) dilute sulfuric acid solution for chemical conditioning before pre-mixing. The dilute acid solution was gradually added dropwise under online pH sensor monitoring, precisely adjusting the initial pH value of the waste spawn to 6.3. This step successfully reduced the amount of ammonia gas escaping during the pre-mixing stage, improving the overall nitrogen fixation efficiency.

[0025] Conditioning and mixing: The crushed and conditioned straw and mushroom sticks are mixed with the collected liquid pig manure (moisture content of about 80%) at a mass ratio of 2:1.5:2.5 into a twin-shaft conditioning and mixing machine. The liquid manure is used to soak the dry materials and mix them evenly.

[0026] Step S1-2: Mixing ingredients Reference Figure 2 The pretreated mixture is continuously fed into a high-efficiency granulation mixer using a high-precision quantitative feeder. Real-time monitoring with an online near-infrared monitor allows for adjustment of the material ratio, precisely controlling the overall carbon-to-nitrogen ratio (C / N) at 27:1. Simultaneously, real-time monitoring with an online near-infrared detector adjusts the water replenishment, stabilizing the initial moisture content of the mixture at 60% (within the optimal fermentation moisture range of 55%-65%), ensuring sufficient moisture and oxygen diffusion channels for microbial reproduction in the early stages of fermentation.

[0027] Steps S1-3: Aerobic fermentation and step-by-step synergistic control Reference Figure 3 , Figure 4 , Figure 5The uniformly mixed material is continuously fed into a fully automated aerobic fermentation chamber equipped with a jacketed temperature control system and a bottom matrix aeration system (the effective volume of the chamber can be set to 50m³). 3 The fermentation process takes place in a closed system. The fermentation chamber is equipped with a jacketed temperature control system and a bottom matrix aeration system. The total fermentation cycle is set to 120 hours. The intelligent control system executes a tiered collaborative control strategy based on real-time data feedback from the online multi-point matrix sensor network built into the fermentation chamber.

[0028] Three sampling layers are evenly arranged vertically in the fermentation chamber, with five monitoring points horizontally positioned in each layer. Each monitoring point integrates an infrared temperature sensor and an insertable conductivity-pH composite electrode. A TDLAS ammonia concentration monitor is installed at the exhaust pipe of the fermentation chamber to achieve real-time acquisition of the micro-zone fermentation status, with a sampling frequency of once every 5 minutes.

[0029] During the warming period (0-24h): the central control system instructs the bottom matrix aeration system to operate at a temperature of 0.08m. 3 / (m 3 A variable frequency pneumatic power supply is used to provide aeration at a rate of ·min. The temperature inside the fermentation chamber is steadily increased to 52°C at a rate of 2°C / h by utilizing the heat generated from the bio-fermentation of thermophilic microorganisms within the material itself. Infrared temperature sensor data shows that the thermophilic microbial population in the material enters the logarithmic growth phase after 12 hours, creating conditions for the succession of thermophilic microorganisms.

[0030] High-temperature holding period (24h-96h): The control system sets the target temperature inside the fermentation chamber to 60±2°C. During actual operation, the temperature stabilizes between 58-62°C. At the 48th hour, due to vigorous microbial metabolism, the micro-area monitoring temperature reaches 65.5°C. The control system then activates the jacket cooling water circulation and simultaneously increases the bottom aeration rate to 0.2 m³. 3 / (m 3 Forced cooling is performed (min), and the temperature is controlled to drop back to 60 °C within 30 minutes. During this period, the humidity in the fermentation chamber is maintained at 55%±5% through spray water replenishment and exhaust ventilation. Through real-time pH feedback, automatic control is implemented so that no additional acid-base adjusters are needed, and the pH value is naturally maintained within the range of 6.8-7.2.

[0031] Under these precisely controlled conditions, sample analysis showed that compared to the control group without precise control, the degradation rate of lignocellulose increased by 62% in this stage, and the content of active humic acid, rich in carboxyl and phenolic hydroxyl groups, increased from the initial 4.2% to 18.5%. Simultaneously, TDLAS monitoring showed that the cumulative ammonia emissions were reduced by 78% compared to the traditional process, indicating that most of the ammonium nitrogen was fixed in situ. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that strong hydrogen and ionic bonds formed between active humic acid and ammonium nitrogen, generating a network-like complex structure of organic slow-release nitrogen fixative.

[0032] Cooling and composting period (96h-120h): Gradually reduce aeration rate to 0.03 m³ / h. 3 / (m 3 (min). As material metabolism and heat generation decrease, the temperature naturally drops to ambient temperature. At this point, macromolecules are fully degraded and reorganized, forming a humic matrix with a high content of acidic functional groups. Its asymmetric abundance is extremely suitable for the special requirements of tea trees for free amino acids and fulvic acid.

[0033] Steps 1-4: The fermented and decomposed product is fed into a drum screen (5 mm mesh size) via a discharge screw conveyor. The undersize material (particle size ≤ 5 mm) is the finished product. The finished product is then conveyed to a fully automated packaging and palletizing line, where a six-degree-of-freedom heavy-duty industrial robotic arm performs the packaging operation.

[0034] The robotic arm, equipped with a machine vision system, identifies and positions packaging bags on the conveyor line using an adaptive gripping control algorithm. The end effector first drives dual pneumatic grippers to clamp the bags on both sides, while a vacuum suction cup assembly adheres to the top surface of the bag for positioning assistance. The bag is then gripped, moved to the sealing station, and automatically labeled (containing batch and nutrient information), before being heat-sealed in conjunction with the packaging line. Finally, the robotic arm stacks the finished bags on a pallet in a "five-pack" arrangement. Actual production tests show that the complete automatic packaging cycle for a single 25kg bag is consistently within seconds.

[0035] Example 2: This example demonstrates an implementation plan for introducing domestic sewage sludge for co-fermentation to produce non-edible crop or landscaping fertilizer.

[0036] S2-1 Raw material pretreatment: Urban greening waste (twigs, fallen leaves) and waste edible mushroom sticks are recycled and crushed in two stages by a twin-shaft crusher to control the particle size to 3~8 mm.

[0037] At the raw material end, dewatered and conditioned domestic sewage sludge (moisture content 45%, pre-treated with heavy metal passivation) is introduced and fed into the conditioning mixer along with crushed plant fiber materials and livestock manure. In the S2-2 mixing and batching process, the material ratio is adjusted through an intelligent weighing and batching system in a high-efficiency granulation mixer, controlling the overall carbon-nitrogen ratio (C / N) of the mixture to be 25:1, and the initial moisture content to be controlled at 65%.

[0038] S2-3. Aerobic Fermentation and Quality Control: Materials are continuously fed into a fully automated aerobic fermentation chamber, with the total fermentation cycle set at 144 hours.

[0039] During the warming period (0-24h): the aeration rate is set to 0.05m³. 3 / (m 3 The temperature inside the fermentation chamber was increased to 50 °C at a rate of 1.5 °C / h (min).

[0040] High-temperature holding period (24h-96h): Maintain the internal temperature at 55 °C~60 °C. When the temperature detected by the micro-area infrared sensor exceeds 65 °C, the intelligent system will activate the jacket cooling water circulation and increase the aeration rate to 0.2m³. 3 / (m 3 Active temperature control was implemented (min). Ambient humidity was maintained at 60%, and pH was kept at 7.5. This high-temperature period lasted for over 72 hours, completely killing pathogens, parasite eggs, and weed seeds in sewage sludge and livestock manure, achieving the harmless treatment standard.

[0041] Cooling and composting period (96h-144h): Gradually reduce aeration rate to 0.02m³. 3 / (m 3 ·min).

[0042] S2-4. Microbial Technology Upgrade: During the cooling and maturation period of fermentation, when the sensor network detects that the material temperature has naturally dropped to 42℃, the intelligent control system activates the quantitative spraying device at the top of the fermentation chamber to quantitatively spray a compound functional microbial agent (including a mixed solution of Bacillus subtilis, Bacillus thuringiensis, and Bacillus megaterium in equal proportions) into the fermentation chamber. After spraying, aerobic fermentation continues for 18 hours, allowing the functional microbial community to solidify and multiply in the humus substrate, producing a microbial compound fertilizer with growth-promoting and disease-preventing functions.

[0043] S2-5. Screening and Packaging: The decomposed product is screened by a drum screener, and particles with a diameter of ≤5 mm are fed into the automated packaging and palletizing system. A multi-degree-of-freedom heavy-duty industrial robotic arm, combined with a machine vision adaptive algorithm, completes the gripping, labeling, sealing, and palletizing of a single bag of fertilizer within a 10-second cycle.

[0044] Example 3: This example illustrates how to flexibly produce various specialized organic fertilizers using the same production equipment by adjusting key process parameters based on the nutrient requirements of the target crop. Its core adjustment logic refers to... Figure 6 As shown, precise customization of product functions can be achieved by changing the raw material formula and process control points.

[0045] Step S3-1: Determine the target crop and customized parameter map First, determine the target crop type (e.g., fruit trees, leafy vegetables, or landscaping plants) based on market demand. Consult a pre-stored crop demand knowledge base (which is linked to the intelligent control system) to obtain the optimal set of growth parameters for the specific crop, including but not limited to: the appropriate ratio of free amino acids and fulvic acid in fertilizers, the desired nitrogen slow-release intensity, and the need for specific functional microorganisms (such as growth promoters and disease preventers).

[0046] This embodiment uses the production of "high-nitrogen slow-release organic fertilizer for fruit trees" as an example for illustration.

[0047] Step S3-2: Differentiated adjustment of raw material formulation Reference Figure 6 The adjustment logic shown applies the following differentiated adjustments based on the needs of fruit tree-specific fertilizers: Adjusting the proportion of waste mushroom substrate: To increase the content of free amino acids and fulvic acid in the fertilizer, thereby promoting root development and fruit quality, the mass ratio of waste mushroom substrate in the raw materials was increased from the conventional 25% to 35%. At the same time, the ratio of straw and livestock manure was adjusted accordingly to ensure that the total carbon-nitrogen ratio (C / N) of the mixture was still controlled within the target range (25-30):1. In this embodiment, it was precisely controlled at 28:1.

[0048] Selective introduction of exogenous materials: Given that this product is targeted at edible economic crops (fruit trees), no domestic sewage sludge will be introduced. Only straw, waste mushroom substrate, and livestock and poultry manure will be used as the core fermentation raw materials.

[0049] Step S3-3: Adaptive process control of the fermentation process After the materials are mixed evenly (initial moisture content controlled at 60%), they are sent to a fully automated aerobic fermentation chamber. The total fermentation cycle is set to 132 hours. The intelligent control system executes a step-by-step collaborative control strategy basically the same as in Example 1, but is finely adjusted during the high-temperature holding period (24h-96h) based on the higher requirements of the fruit tree-specific fertilizer for nitrogen slow-release intensity. Temperature control: The target temperature is maintained within the upper limit, i.e., 62°C-65°C, and the duration of high temperature is extended. Through jacket cooling and aeration linkage, the temperature is ensured to operate stably within this range for over 60 hours. The stronger high-temperature stress further promotes the deep degradation of lignocellulose, generating more active humic acid with complexing capabilities.

[0050] Humidity and pH control: Maintain ambient humidity at 55% and pH value between 6.8 and 7.2. A stable pH environment is conducive to the retention of ammonium nitrogen and the efficient formation of humic acid-nitrogen complexes.

[0051] Step S3-4: Optional spraying of functional microorganisms Based on the nutrient requirements of fruit trees, this embodiment selects the cooling and composting period to implement the microbial agent upgrade step. When the material temperature drops to 42°C, a quantitative amount of compound functional microbial agent is sprayed. Unlike Example 2, to enhance the effects of phosphorus and potassium solubilization and disease prevention, this embodiment uses a mixed bacterial solution of Bacillus megaterium and Bacillus mucilaginosus (ratio 1:1). After spraying, fermentation continues for 20 hours to obtain a special microbial fertilizer for fruit trees that combines nitrogen slow release and soil nutrient activation functions.

[0052] Step S3-5: Screening and Automated Packaging The screening, packaging, and palletizing steps are the same as in Example 1. The final product is a slow-release nitrogen organic fertilizer for fruit trees with a particle size ≤5mm, a total nutrient (N+P2O5+K2O) content of 7.1%, and an active humic acid content as high as 19.2%. Its nitrogen release curve (obtained through laboratory leaching tests) shows that the nitrogen supply intensity during the simulated critical periods of fruit tree nutrient demand (flower bud differentiation and fruit enlargement) is 35% higher than that of conventional organic fertilizers, while the total fertilizer utilization rate is expected to increase by more than 48%.

[0053] Summary of customized production: This embodiment clearly demonstrates how to base on the attached Figure 6 The aforementioned logic, by changing the proportion of waste mushroom substrate (25% for conventional use → 35% for fruit tree specific use) and selectively introducing domestic sewage sludge (not introduced for fruit tree specific use), and supplemented by fine-tuning of fermentation control parameters (such as strengthening high-temperature holding intensity) and flexible compatibility of functional microbial agents, enables rapid switching from general-purpose products to high-value-added specific products on the same production line, fully demonstrating the flexibility and advanced adaptability of the method of this invention.

[0054] Comparative Example 1: The traditional composting process (excluding the core control strategy of this invention) uses the same raw material ratio as Example 1 (straw, waste mushroom substrate, pig manure, carbon-nitrogen ratio 27:1, initial moisture content 60%), but natural composting fermentation is carried out on a traditional windrow fermentation and turning production line. The fermentation cycle is 35 days, during which jacket temperature control and bottom matrix stepped aeration cannot be coordinated and controlled, and oxygen is replenished by manual turning at regular intervals.

[0055] Experimental effect data verification: To verify the technical effect of the present invention, the products obtained in Example 1 and Example 2 were compared with the product of Comparative Example 1 in performance testing and application comparison experiments. The relevant parameters and results are shown in the table below:

[0056] Analysis of Experimental Conclusions The experimental data in the table above shows that: 1. The method of this invention significantly improves nitrogen fixation efficiency and fermentation efficiency. The overall nitrogen fixation efficiency of the three embodiments reached 92.5% (Example 1), 89.1% (Example 2), and 91.8% (Example 3), respectively, while Comparative Example 1 (traditional windrow composting) only achieved 61.4%. This indicates that by pre-conditioning with dilute acid (adjusting the initial pH of the waste substrate to 6.0-6.5) and combining this with precise and synergistic control of temperature, humidity, and pH during the high-temperature holding period, ammonia escape was effectively suppressed, and ammonium nitrogen was efficiently converted into a network-structured, slow-release organic nitrogen-fixing body. Furthermore, the fermentation and maturation cycle of this invention is only 120-144 hours (approximately 5-6 days), far shorter than the 35 days of the traditional process, resulting in a production efficiency increase of more than 5 times.

[0057] 2. The product's nutrient and active humic acid content are significantly increased. The total nutrient (N+P2O5+K2O) contents of Examples 1, 2, and 3 were 6.8%, 6.2%, and 7.1%, respectively, and the active humic acid contents were 18.5%, 16.2%, and 19.2%, respectively, all significantly better than the 4.3% and 8.1% of Comparative Example 1. In particular, Example 3 (high-nitrogen slow-release organic fertilizer for fruit trees) achieved the highest total nutrient content (7.1%) and active humic acid content (19.2%) by increasing the proportion of waste mushroom substrate from the conventional 25% to 35% and strengthening the high-temperature holding period (maintaining 62-65℃ for more than 60 hours). This fully demonstrates that the functional quality of the product can be optimized by adjusting the raw material ratio and process parameters.

[0058] 3. Fertilizer utilization rate is significantly improved, and the slow-release effect is outstanding. The fertilizer utilization rates of Examples 1, 2, and 3 were increased by 46.8%, 45.2%, and 48.0% respectively compared to traditional organic fertilizers, all consistently achieving the expected target of over 45%. Combined with... Figure 5 The nitrogen release rate comparison curves shown demonstrate that in the organic fertilizer prepared by this invention, the network complex structure formed by active humic acid and ammonium nitrogen through hydrogen and ionic bonds effectively inhibits the rapid hydrolysis and leaching of nitrogen, resulting in a smoother nitrogen release curve that closely matches the nutrient requirements of crops (especially tea trees and fruit trees). In Example 3, the nitrogen supply intensity during the critical nutrient requirements of fruit trees (flower bud differentiation and fruit enlargement stages) was increased by 35% compared to conventional organic fertilizers, demonstrating excellent slow-release matching.

[0059] 4. Automated packaging significantly improves production efficiency. By employing a multi-degree-of-freedom heavy-duty industrial robotic arm in conjunction with a machine vision adaptive grasping algorithm, the complete cycle time for automated packaging of a single bag is consistently maintained at 10-12 seconds (11 seconds in Example 1, 10 seconds in Example 2, and 11 seconds in Example 3), while manual packaging in Comparative Example 1 takes over 45 seconds per bag. This invention improves packaging efficiency by 3-4 times while significantly reducing labor intensity and labor costs, making it suitable for large-scale industrial production.

[0060] 5. Example 3 further validates the product's potential for customized production. Example 3, while maintaining high nitrogen fixation efficiency (91.8%) and a short fermentation cycle (132h), successfully prepared a fruit tree-specific fertilizer with superior total nutrients (7.1%) and active humic acid (19.2%) by increasing the proportion of waste substrate (from the conventional 25% to 35%), strengthening the control of the high-temperature holding period (62-65℃), and selectively combining functional microbial agents (Bacillus megaterium and Bacillus spp.). The fertilizer utilization rate was improved by 48.0%. This fully demonstrates that the method of the present invention has extremely strong process flexibility, and can quickly adjust the raw material formula and key control parameters according to the needs of the target crop (such as tea trees, fruit trees, landscaping, etc.), realizing customized production of "one line, multiple products".

[0061] Overall conclusion: This invention successfully solves common technical problems of traditional organic fertilizer production, such as long production cycles, large nitrogen losses, poor slow-release performance, and low automation levels, by integrating a series of innovative technologies, including pre-treatment chemical conditioning, stepped temperature, humidity, and pH synergistic control, real-time feedback from an online multi-point matrix sensor network, and automated packaging and palletizing. The resulting organic fertilizer product exhibits significant nitrogen slow-release characteristics, with fertilizer utilization increasing by more than 45% compared to traditional products, and can be flexibly customized to meet the needs of different crops. This technology achieves efficient, low-carbon, and intelligent resource utilization of agricultural waste, possessing extremely high industrial application value and market promotion prospects. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The invention has been further described above with reference to specific embodiments; however, it should be understood that the specific descriptions herein should not be construed as limiting the substance and scope of the invention. Various modifications made by those skilled in the art to the above embodiments after reading this specification are within the scope of protection of this invention.

Claims

1. A method for preparing nitrogen-slow-release organic fertilizer by aerobic fermentation of agricultural waste, characterized in that, Includes the following steps: Raw material pretreatment: The recycled straw and waste mushroom sticks are crushed in two stages to control the particle size of the crushed material to be 3~8 mm, and then mixed with livestock and poultry manure for conditioning; Mixing and batching: The pretreated materials are fed into a high-efficiency granulation mixer. Through precise metering, the carbon-nitrogen ratio of the mixture is adjusted to (25~30):1, and the initial moisture content is controlled at 55%-65%. Aerobic fermentation and quality control: The uniformly mixed material is continuously fed into a fully automated aerobic fermentation chamber with jacket temperature control and bottom matrix aeration system for closed fermentation. The total fermentation cycle is 72-144 hours. An intelligent control system is used to construct a step-by-step collaborative control strategy based on the fermentation cycle to collaboratively manage the temperature, humidity, oxygen concentration and pH value during the fermentation process. Screening and Packaging: The fermented and decomposed product is fed into a drum screen to screen out particles with a diameter of ≤5 mm as nitrogen slow-release organic fertilizer. The product is then automated by using a multi-degree-of-freedom heavy-duty industrial robotic arm for weighing, sealing, packaging and palletizing.

2. The method for preparing nitrogen-slow-release organic fertilizer from agricultural waste by aerobic fermentation according to claim 1, characterized in that: In the aerobic fermentation and quality control steps, the step-by-step synergistic control strategy specifically includes: During the warming period (0-24h): control the aeration rate of the bottom matrix aeration system to 0.05~0.1m³. 3 / (m 3 (·min), utilizing the biological fermentation heat of the material itself to raise the temperature inside the fermentation chamber to 50°C~55°C at a rate of 1.5°C / h~2.5°C / h, promoting the large-scale reproduction of thermophilic microorganisms; High-temperature holding period (24h-96h): Maintain the temperature inside the fermentation chamber at 55°C-65°C. When the temperature exceeds 65°C, the intelligent control system will activate the jacket cooling water circulation and increase the aeration rate to 0.2 m³ / h. 3 / (m 3 Cooling is carried out by (min); at the same time, the humidity in the fermentation chamber is controlled at 50%~60%, and the pH value is maintained at 6.5~7.5 to promote the degradation of lignocellulose and convert biomass nitrogen into solid phase cellular nitrogen; Cooling and composting period (96h-144h): Gradually reduce aeration rate to 0.02-0.05 m³ / h. 3 / (m 3 (·min), allowing the material temperature to naturally drop to ambient temperature, forming a humic matrix with a high content of acidic functional groups.

3. The method for preparing nitrogen-slow-release organic fertilizer from agricultural waste by aerobic fermentation according to claim 2, characterized in that: The slow-release mechanism of the nitrogen-slow-release organic fertilizer is as follows: through precise and coordinated control of temperature, humidity and pH during the high-temperature holding period, the lignocellulose in the mushroom sticks and straw is promoted to undergo directional degradation into active humic acid rich in carboxyl and phenolic hydroxyl groups. This active humic acid and ammonium nitrogen produced by the degradation of livestock and poultry manure are physically adsorbed and chemically chelated through hydrogen bonds and ionic bonds to form a network complex structure of organic slow-release nitrogen fixation body, thereby inhibiting the rapid hydrolysis and leaching of nitrogen and achieving a fertilizer utilization rate that is more than 45% higher than that of traditional organic fertilizers.

4. The method for preparing nitrogen-slow-release organic fertilizer by aerobic fermentation of agricultural waste according to claim 1, characterized in that: In the raw material pretreatment, the waste mushroom sticks are pre-treated with chemical conditioning, and their initial pH value is adjusted to 6.0-6.5 using a dilute acid solution before being mixed with the livestock and poultry manure, in order to suppress the escape of ammonia during the premixing stage and improve the nitrogen fixation efficiency of the entire process.

5. The method for preparing nitrogen-slow-release organic fertilizer by aerobic fermentation of agricultural waste according to claim 1, characterized in that: The fully automated aerobic fermentation chamber is equipped with an online multi-point matrix sensor network. The sensor network includes infrared temperature sensors, insertable conductivity pH composite electrodes, and laser tunable diode absorption spectroscopy (TDLAS) ammonia concentration monitors that are uniformly distributed at different depths of the fermentation solid material, in order to provide real-time feedback of micro-zone fermentation status parameters to the intelligent control system.

6. The method for preparing nitrogen-slow-release organic fertilizer from agricultural waste by aerobic fermentation according to claim 1, characterized in that: The method also includes a microbial technology upgrade step: during the cooling and composting period of the aerobic fermentation, when the material temperature drops to 40-45 ℃, a compound functional microbial agent is quantitatively sprayed into the fermentation chamber. The functional microbial agent includes a mixed bacterial solution of Bacillus subtilis, Bacillus megaterium, and Bacillus megaterium. After spraying, the aerobic state is maintained for another 12-24 hours to produce a microbial fertilizer with growth-promoting and disease-preventing functions.

7. The method for preparing nitrogen-slow-release organic fertilizer by aerobic fermentation of agricultural waste according to claim 1, characterized in that: In the screening and packaging step, the multi-degree-of-freedom heavy-duty industrial robotic arm adopts an adaptive gripping control algorithm based on machine vision positioning. Its end effector is equipped with dual-sided pneumatic grippers and vacuum suction cups to grip, move, label, and seal single bags of organic fertilizer in conjunction with the packaging line. The full cycle of automatic packaging of a single bag is stable at 10-12 seconds.

8. The method for preparing nitrogen-slow-release organic fertilizer from agricultural waste by aerobic fermentation according to claim 1, characterized in that: The organic fertilizer prepared by this method can be customized to produce a special organic fertilizer for tea trees that meets the growth needs of tea by adjusting the proportion of waste mushroom sticks in the raw materials to change the asymmetric abundance of free amino acids and fulvic acid in the fertilizer; or, dehydrated and conditioned domestic sludge can be introduced into the raw materials to participate in the aerobic fermentation process to produce special fertilizer for non-edible crops or landscaping.

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