Closed-loop vegetable cultivation liquid fertilizer system and method based on mineral organic compound fermentation

Abstract

The invention discloses a closed-loop vegetable cultivation liquid fertilizer system and method based on mineral organic compound fermentation. According to the method, potassium feldspar powder and phosphate rock powder are subjected to microwave activation and acidolysis treatment, rapeseed cakes are subjected to enzymolysis pretreatment, and microelements released in minerals are fully combined with organic degradation products to generate stable nutrients through the steps of acidification fermentation, chelation reaction and decomposition stabilization. The system integrates a percolate recovery and purification technology, the percolate generated in the fermentation process is purified and then recycled, meanwhile, vegetable cultivation closed loop and intelligent monitoring of the Internet of Things are combined, accurate supply of liquid fertilizer, resource recycling and fertilizer efficiency early warning are achieved, the fertilizer efficiency is effectively prolonged, the crop quality is improved, and water resources are saved; and the method has remarkable economic and ecological benefits. According to the system, the traditional process is optimized, the fertilizer conversion efficiency and the crop growth benefit are remarkably improved, and the production cost and the environmental risk are reduced.

Description

Technical Field

[0001] The present invention relates to organic fertilizer preparation and application technology, and in particular to a preparation method and system for closed-loop vegetable cultivation liquid fertilizer based on mineral-organic composite fermentation, belonging to the technical fields of organic agriculture and intelligent fine fertilization. Background Art

[0002] Existing organic fertilizer production technology mainly relies on the degradation of organic raw materials by microorganisms under natural conditions to produce nutrient-rich organic fertilizer. Although traditional fermentation processes can improve soil fertility, they have the following drawbacks:

[0003] First, the degradation process is slow and the process control is imprecise, resulting in a nutrient release rate that is unable to meet the needs of rapid crop growth;

[0004] Secondly, the leachate produced during the fermentation process lacks effective collection and reuse measures, resulting in waste of water resources and potential environmental pollution;

[0005] Third, traditional fertilizer preparation equipment and processes have a low level of intelligence, making it impossible to achieve real-time monitoring and dynamic regulation of the fermentation process and fertilizer efficiency, resulting in unstable quality of liquid fertilizers and poor sustainability of fertilizer efficiency.

[0006] In recent years, some technologies have attempted to improve fermentation efficiency by introducing high-efficiency microbial strains and improving reactor design. However, single measures are unlikely to fully address issues such as low nutrient utilization, resource waste, and environmental pollution. At the same time, modern agriculture, especially greenhouse vegetable cultivation, places higher demands on fertilizer application, requiring not only efficient nutrient conversion but also precise fertilizer supply and closed-loop resource recycling. Summary of the Invention

[0007] In response to the above technical problems, the purpose of the present invention is to provide a closed-loop vegetable cultivation liquid fertilizer preparation method and system based on mineral-organic composite fermentation, which produces stable and efficient liquid fertilizer by pre-treating mineral raw materials and organic raw materials, acidification fermentation, chelation reaction, and composting and stabilization. At the same time, through the recovery and purification of leachate and the closed-loop integration of the vegetable cultivation system, the recycling of resources and the effective control of environmental pollution are achieved. In addition, the present invention also integrates a fertilizer efficiency early warning model based on the Internet of Things to monitor the crop growth status and substrate nutrients in real time, dynamically optimize the supply and preparation process of liquid fertilizer, and further improve the overall system efficiency and agricultural production benefits.

[0008] In a first aspect, the present invention provides a method for preparing a closed-loop liquid fertilizer for vegetable cultivation based on mineral-organic composite fermentation, comprising the following steps:

[0009] Raw material pretreatment step: microwave activation and acid hydrolysis treatment of mineral raw materials, and enzymatic hydrolysis treatment of organic raw materials;

[0010] Acidification and fermentation step: After the pretreated mineral raw materials are mixed with the organic raw materials, they are placed in an acidification fermentation tank to initiate a preliminary hydrolysis reaction under suitable temperature and pH conditions to generate organic acids and degradation intermediates;

[0011] Chelating reaction step: the acidification reaction product is transferred to a chelating reaction tank, and an appropriate amount of auxiliary materials is added to adjust the pH so that the trace elements released from the minerals fully contact with the organic degradation products and undergo a chelating reaction to form a stable complex;

[0012] Composting and stabilization step: The chelation reaction products are transferred to a composting and stabilization tank. Under continuous oxygen supply conditions and with the help of supporting microbial communities, the organic matter is completely metabolized to generate stable nutrients, thereby forming liquid fertilizer.

[0013] As a preferred embodiment, the raw material pretreatment step is specifically as follows:

[0014] The mineral raw materials include potassium feldspar powder and phosphate rock powder, wherein the potassium feldspar powder is activated by treating with a 600-900W microwave for 3-10 minutes, and the phosphate rock powder is acid-lyzed by soaking in a citric acid solution with a pH of 3.0-4.0 for 1.5-2 hours;

[0015] The organic raw material includes rapeseed cake, which is enzymatically hydrolyzed with an appropriate amount of alginate lyase at 45-50° C. for 1 hour.

[0016] As a preferred embodiment, the acidification and fermentation step is specifically as follows:

[0017] The pretreated mineral raw materials and organic raw materials are uniformly mixed in a weight ratio of 1:1 to 1:2 and then put into an acidification fermentation tank for a hydrolysis reaction at 35 to 40°C and a pH of 5.5 to 6.0 for 6 to 8 hours to generate organic acids and other degradation intermediates;

[0018] and / or,

[0019] The acidification and fermentation step also adopts a composite bacterial agent cooperative fermentation technology, wherein the composite bacterial agent includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria and brown algae lyase.

[0020] As a preferred embodiment, the chelating reaction step is specifically as follows:

[0021] The acidified product is transferred to a chelation reaction tank, and an appropriate amount of humic acid or its derivatives is added to adjust the pH of the system to 7.0±0.5;

[0022] The reaction is carried out at a temperature of 45-50°C and under appropriate stirring conditions for 1-2 hours to allow the trace elements released by the minerals to fully contact with the organic degradation products to form a stable complex that is easily absorbed by plants;

[0023] and / or,

[0024] The auxiliary materials further include nutritional supplements, which contain at least one of dolomite powder and potassium magnesium sulfate.

[0025] As a preferred embodiment, the decomposition and stabilization step is specifically as follows:

[0026] The chelation reaction product is transferred to a composting and stabilization tank and continuously supplied with oxygen at 28-32°C;

[0027] With the help of supporting microbial communities containing nitrogen-fixing bacteria, phosphate-solubilizing bacteria and EM bacteria, the reaction takes 72 hours to completely metabolize the organic matter and achieve nutrient stabilization, thus forming liquid fertilizer.

[0028] As a preferred solution, it also includes:

[0029] Leachate recycling step: The small amount of leachate produced during the fermentation process is transported to the recovery and purification module through a pipeline. Nanobubble aeration technology is used to remove suspended particles in the leachate, and harmful impurities are further removed through biochar filtration. The purified liquid is then returned to the raw material pretreatment and acidification fermentation steps, mixed with new raw materials to participate in the next round of reaction, thus forming an internal closed-loop circulation of liquid fertilizer.

[0030] As a preferred solution, it also includes a closed-loop integrated step for vegetable cultivation.

[0031] Supply purified liquid fertilizer directly to the vegetable cultivation system;

[0032] In the vegetable cultivation system, an IoT-based fertilizer efficiency early warning model is integrated, and leaf spectral analysis and substrate solution real-time monitoring technology are used to collect crop growth status and substrate nutrient data in real time, and compare them with preset fertilizer efficiency standards;

[0033] Dynamically adjust liquid fertilizer supply and preparation process based on monitoring data;

[0034] At the same time, the biomass residues and microecological feedback generated during the crop growth process are collected and fed back to the raw material pretreatment step as organic raw materials, thus forming a closed-loop circulation of materials and energy between the fermentation system and the vegetable cultivation system.

[0035] In a second aspect, the present invention provides a closed-loop liquid fertilizer system for vegetable cultivation based on mineral-organic composite fermentation, comprising:

[0036] Fermentation system, including a multi-stage fermentation tank group, a raw material pretreatment module, and a leachate recovery and purification module;

[0037] The raw material pretreatment module is used to perform microwave activation and acid hydrolysis treatment on mineral raw materials, and enzymatic hydrolysis treatment on organic raw materials;

[0038] The multi-stage fermentation tank group includes an acidification fermentation tank, a chelation reaction tank, and a composting stabilization tank, which are used in sequence to start the hydrolysis reaction, promote the chelation reaction between the trace elements released by the minerals and the organic degradation products, and complete the complete metabolism of the organic matter under the continuous oxygen supply and the synergistic action of microorganisms;

[0039] The leachate recovery and purification module uses nanobubble aeration and biochar filtration technology to purify the leachate produced during the fermentation process and returns the purified liquid to the fermentation system, forming an internal closed-loop circulation;

[0040] The vegetable cultivation system directly receives liquid fertilizer supplied by the fermentation system, collects biomass residues and microecological feedback generated during crop growth, and feeds them back to the pretreatment module as organic raw materials, realizing a closed-loop circulation of materials and energy;

[0041] The intelligent control system integrates EC, pH, ORP, and DO sensors and a central control unit. Through the Internet of Things platform, it monitors and transmits data in real time on key parameters in each link of fermentation, leachate recovery, purification, and vegetable cultivation. It also dynamically adjusts process parameters according to preset standards to achieve fertilizer efficiency early warning and process optimization.

[0042] In some technical solutions, the acidification fermentation tank is provided with a dedicated agitator to ensure uniform mixing of the reactants;

[0043] The chelation reaction tank is equipped with an ultrasonic dispersion device to prevent mineral precipitation;

[0044] The composting and stabilization tank is equipped with a temperature control device and a suitable biofilm carrier.

[0045] In some technical solutions, the intelligent control system includes:

[0046] Multi-parameter monitoring unit for real-time data collection of EC, pH, ORP, and DO in fermentation, exudate purification, and vegetable cultivation systems;

[0047] The central control unit compares the monitoring data with the preset fertilizer efficiency standards and automatically adjusts the process parameters of oxygen supply, temperature, pH value and feeding;

[0048] The IoT communication module enables wireless data transmission and remote monitoring, while integrating a fertilizer efficiency early warning model based on leaf spectral analysis and real-time monitoring of substrate solution to dynamically optimize liquid fertilizer preparation and supply.

[0049] The present invention adopts mineral-organic composite fermentation technology, combines the closed-loop integration of the fermentation system and the vegetable cultivation system, and intelligent control and fertilizer efficiency early warning technology, which has the following beneficial effects:

[0050] 1. The present invention significantly improves nutrient conversion efficiency by utilizing mineral-organic composite fermentation technology. During pretreatment, the mineral raw materials undergo microwave activation and acid hydrolysis, fully releasing key elements (such as K, P, and Ca) from potassium feldspar powder and phosphate rock powder. Simultaneously, enzymatic hydrolysis of the organic raw materials generates organic degradation products that, during the acidification and chelation process, form stable complexes with the trace elements released from the minerals, achieving efficient nutrient conversion and stabilization, thereby enhancing the bioavailability of the liquid fertilizer.

[0051] 2. This invention also achieves closed-loop resource recycling through the recovery, purification, and recycling of leachate. The small amount of leachate produced during the fermentation process is purified through processes such as nanobubble aeration and biochar filtration, and then returned to the pretreatment and acidification fermentation steps to mix with new raw materials for the reaction. This not only conserves water resources but also reduces the risk of environmental pollution caused by nutrient loss, thereby improving resource utilization of the entire system.

[0052] 3. This invention utilizes a complex fermentation system with a supporting microbial community (including nitrogen-fixing, phosphate-solubilizing, and EM bacteria) to accelerate the degradation and complete metabolism of organic matter. The synergistic effect of the complex fermentation system during the acidification and fermentation phase accelerates the production of organic acids and other intermediates. During the mature and stable phase, continuous oxygen supply and the synergistic effect of the microorganisms further achieve complete metabolism of organic matter and nutrient stabilization, resulting in a liquid fertilizer with excellent fertilizer efficiency and long-lasting properties.

[0053] 4. This invention integrates an IoT-based intelligent monitoring and fertilizer efficiency early warning system. By collecting key parameters (such as EC, pH, ORP, DO, leaf spectra, and substrate nutrient data) from fermentation, leachate purification, and vegetable cultivation in real time, it dynamically controls process parameters and fertilizer efficiency. This intelligent system automatically adjusts process conditions such as oxygen supply, temperature, pH, and feed rate according to preset fertilizer efficiency standards, ensuring that the liquid fertilizer preparation process always operates at optimal levels, effectively improving crop growth efficiency.

[0054] 5. The present invention constitutes an integrated closed-loop circulation system of a fermentation system and a vegetable cultivation system, which not only realizes the efficient preparation of liquid fertilizer, but also forms a two-way circulation of matter and energy through crop growth feedback during the vegetable cultivation process, effectively reducing production costs, improving resource utilization and environmental protection benefits, and reflecting obvious economic and ecological benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a control logic diagram of a closed-loop liquid fertilizer system for vegetable cultivation based on mineral-organic composite fermentation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following examples are only used to illustrate the technical solution of the present invention more clearly, and are not intended to limit the scope of protection of the present invention.

[0057] According to an embodiment provided by the present invention, a method for preparing a closed-loop liquid fertilizer for vegetable cultivation based on mineral-organic composite fermentation comprises the following steps:

[0058] Firstly, potassium feldspar powder and phosphate rock powder were selected as mineral raw materials, and rapeseed cake was used as the main organic raw material. Microwave activation and acid hydrolysis were used as pretreatment of the mineral raw materials.

[0059] Specifically, potassium feldspar powder was microwaved at approximately 800W for approximately 5 minutes to partially dissociate its crystal structure. Subsequently, the phosphate rock was soaked in a citric acid solution with a pH of approximately 4.0 for 2 hours, effectively increasing the release rate of key elements such as K, P, and Ca from the mineral. Simultaneously, the rapeseed cake was treated with an appropriate amount of alginate lyase at 50°C for 1 hour to achieve enzymatic hydrolysis, reducing anti-nutritional factors while initially degrading the organic components, generating some organic acids and low-molecular-weight organic matter, which provide reactive substances for subsequent reactions.

[0060] Next, the pretreated mineral feedstock is evenly mixed with the organic feedstock in a weight ratio of 1:1 to 1:2 and placed in an acidification fermentation tank. A hydrolysis reaction is carried out for 6 to 8 hours at a suitable temperature (e.g., 35-40°C) and pH (approximately 5.5-6.0). During this time, some organic matter is converted into organic acids and other degradation intermediates are generated. In this embodiment, a composite bacterial agent synergistic fermentation technology is also used. The composite bacterial agent contains nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and brown algae lyase to accelerate the degradation of organic matter and increase the production rate of organic acids and other intermediates.

[0061] After the acidification reaction is complete, the reaction product is transferred to a chelation reaction tank. At this point, the pH of the reaction system is adjusted to 7.0 ± 0.5 by adding appropriate amounts of auxiliary materials, including humic acid or its derivatives. A nutritional supplement (such as at least one of dolomite powder and potassium and magnesium sulfate) can also be added to allow the trace elements released from the mineral raw materials to fully contact the organic degradation products. The reaction is carried out at 45°C under appropriate stirring conditions for 1 to 2 hours, thereby forming a stable complex that is easily absorbed by plants.

[0062] The chelation reaction products are then transferred to a composting and stabilization tank, where they are continuously oxygenated at 30°C and react for approximately 72 hours with the aid of a supporting microbial community containing nitrogen-fixing, phosphate-solubilizing, and EM bacteria. During this stage, the organic matter is thoroughly metabolized, generating stable nutrients and thus forming liquid fertilizer. The entire fermentation process is also accompanied by the production of a small amount of leachate, which is transported via a dedicated pipeline to a recovery and purification module. Nanobubble aeration is used to remove suspended particles, and biochar filtration is used to remove harmful impurities. The purified liquid is then returned to the raw material pretreatment and acidification fermentation steps, completing an internal closed-loop circulation of the liquid fertilizer.

[0063] In addition to the fermentation system, this embodiment further integrates a vegetable cultivation system. The prepared purified liquid fertilizer is directly supplied to the vegetable cultivation system, providing sufficient water and nutrients for the crops. At the same time, an IoT-based fertilizer efficiency early warning model is set up within the system. Using leaf spectral analysis and real-time monitoring of the matrix solution, real-time data on crop growth status and nutrients in the matrix is collected and compared with preset standards. The liquid fertilizer supply and fermentation process parameters are dynamically adjusted based on the monitoring data. In addition, the biomass residues and microecological effects generated during the vegetable cultivation process are collected and fed back as organic raw materials to participate in the next round of pretreatment, forming a closed-loop circulation of materials and energy between the fermentation system and the vegetable cultivation system.

[0064] According to another embodiment provided by the present invention, referring to Figure 1 It is a closed-loop liquid fertilizer system for vegetable cultivation based on mineral-organic composite fermentation, including a fermentation system, a vegetable cultivation system and an intelligent control system. It realizes the efficient preparation and precise supply of liquid fertilizer, as well as the recycling of resources and real-time regulation of fertilizer efficiency.

[0065] The fermentation system first incorporates a raw material pretreatment module for pre-treating mineral and organic raw materials. Specifically, mineral raw materials (such as potassium feldspar powder and phosphate rock) undergo microwave activation and acid hydrolysis to fully release key elements such as potassium, phosphorus, and calcium. Organic raw materials (such as rapeseed cake and other plant waste) undergo enzymatic hydrolysis to produce organic acids and other low-molecular organic degradation products. The pre-treated mineral and organic raw materials are then mixed in a predetermined ratio and fed into an acidification fermentation reactor. During this stage, the hydrolysis reaction is initiated under suitable temperature and pH conditions. A complex bacterial agent synergistic fermentation technique (such as a combination of nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and brown algae lyase) can be employed to accelerate the degradation of organic matter, producing organic acids and degradation intermediates. The acidified products then enter a chelation reactor, where humic acid or its derivatives, along with necessary nutritional supplements (such as dolomite powder and potassium and magnesium sulfate), are added to the system. Under appropriate pH and stirring conditions, the trace elements released from the minerals combine with the organic degradation products, forming a stable complex that is easily absorbed by plants. Finally, the chelated product is fed into a composting and stabilization reactor. Under continuous oxygenation, a microbial community containing nitrogen-fixing, phosphate-solubilizing, and EM bacteria undergoes a prolonged reaction, completely metabolizing the organic matter and forming stable nutrients, resulting in highly efficient liquid fertilizer. Furthermore, the small amount of leachate produced during the fermentation process is transported via a dedicated pipeline to a recovery and purification module. After purification using nanobubble aeration and biochar filtration technology, the leachate is returned to the fermentation system, completing a closed-loop cycle within the liquid fertilizer.

[0066] As another part of the overall system, the vegetable cultivation system directly receives liquid fertilizer from the fermentation system, providing the crops with the nutrients and water they need. During the vegetable cultivation process, a dedicated collection device collects microecological feedback materials, such as biomass residues and root secretions produced by crop growth. These are fed back to the raw material pretreatment module as organic raw materials for the next round of fermentation, forming a closed material and energy loop between the fermentation system and the vegetable cultivation system.

[0067] The entire system is precisely managed through an integrated intelligent control system. The system is equipped with a multi-parameter monitoring unit that can collect key data such as EC, pH, ORP, DO, etc. in all aspects of fermentation, exudate purification, and vegetable cultivation in real time. At the same time, leaf spectral analysis and matrix solution real-time monitoring technology are used on the vegetable cultivation side to obtain crop growth status and matrix nutrient information. All data are transmitted to the central control unit through the Internet of Things communication module. The system automatically adjusts process parameters such as oxygen supply, temperature, pH value, and feed amount according to preset fertilizer efficiency standards and process requirements to ensure that each link is always operating in the best state and to achieve fertilizer efficiency early warning. In this way, not only can the liquid fertilizer preparation process and supply strategy be dynamically optimized, but also changes in crop nutritional needs can be responded to in a timely manner, further improving crop growth efficiency and the overall economy of the system.

[0068] In the test at the Shouguang base in Shandong, the closed-loop vegetable cultivation liquid fertilizer system and preparation method of the present invention showed obvious superiority. Experimental data showed that the liquid fertilizer prepared by this system has an effective period of 15 to 20 days, while the effective period of traditional organic fertilizer is only 7 to 10 days, and the fertilizer efficiency is improved by about 50% to 100%. In addition, the exudate produced during the fermentation process is purified and recycled, and its recycling rate reaches 87.3%, which achieves a water-saving effect of about 38% compared with the conventional process. In terms of crop quality, the nitrate content of the tomato fruit supplied with the liquid fertilizer in the experiment meets the WHO vegetable safety standards. At the same time, after three consecutive seasons of use, the EC value in the matrix only increased slightly by <0.5mS / cm, indicating that the nutrient balance and closed-loop circulation effect in the system are good. Overall, these experimental results fully demonstrate the significant advantages of the present invention in improving nutrient conversion efficiency, realizing closed-loop circulation of resources, and improving crop fertilizer efficiency and quality.

[0069] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a closed-loop liquid fertilizer for vegetable cultivation based on mineral-organic composite fermentation, characterized in that: The following steps are involved: Raw material pretreatment step: microwave activation and acid hydrolysis treatment of mineral raw materials, and enzymatic hydrolysis treatment of organic raw materials; Acidification and fermentation step: After the pretreated mineral raw materials are mixed with the organic raw materials, they are placed in an acidification fermentation tank to initiate a preliminary hydrolysis reaction under suitable temperature and pH conditions to generate organic acids and degradation intermediates; Chelating reaction step: the acidification reaction product is transferred to a chelating reaction tank, and an appropriate amount of auxiliary materials is added to adjust the pH so that the trace elements released from the minerals fully contact with the organic degradation products and undergo a chelating reaction to form a stable complex; Composting and stabilization step: The chelation reaction products are transferred to a composting and stabilization tank. Under continuous oxygen supply conditions and with the help of supporting microbial communities, the organic matter is completely metabolized to generate stable nutrients, thereby forming liquid fertilizer.

2. The preparation method according to claim 1, characterized in that The raw material pretreatment steps are specifically as follows: The mineral raw materials include potassium feldspar powder and phosphate rock powder, wherein the potassium feldspar powder is activated by treating with a 600-900W microwave for 3-10 minutes, and the phosphate rock powder is acid-lyzed by soaking in a citric acid solution with a pH of 3.0-4.0 for 1.5-2 hours; The organic raw material includes rapeseed cake, which is enzymatically hydrolyzed with an appropriate amount of alginate lyase at 45-50° C. for 1 hour.

3. The preparation method according to claim 1, characterized in that The acidification and fermentation step is specifically as follows: The pretreated mineral raw materials and organic raw materials are uniformly mixed in a weight ratio of 1:1 to 1:2 and then put into an acidification fermentation tank for a hydrolysis reaction at 35 to 40°C and a pH of 5.5 to 6.0 for 6 to 8 hours to generate organic acids and other degradation intermediates; and / or, The acidification and fermentation step also adopts a composite bacterial agent cooperative fermentation technology, and the composite bacterial agent includes nitrogen-fixing bacteria, phosphate-solubilizing bacteria and EM bacteria.

4. The preparation method according to claim 1, characterized in that The chelating reaction step is specifically as follows: The acidified product is transferred to a chelation reaction tank, and an appropriate amount of humic acid or its derivatives is added to adjust the pH of the system to 7.0±0.5; The reaction is carried out at a temperature of 45-50°C and under appropriate stirring conditions for 1-2 hours to allow the trace elements released by the minerals to fully contact with the organic degradation products to form a stable complex that is easily absorbed by plants; and / or, The auxiliary materials further include nutritional supplements, which contain at least one of dolomite powder and potassium magnesium sulfate.

5. The preparation method according to claim 1, characterized in that The decomposition and stabilization steps are specifically as follows: The chelation reaction product is transferred to a composting and stabilization tank and continuously supplied with oxygen at 28-32°C; With the help of supporting microbial communities containing nitrogen-fixing bacteria, phosphate-solubilizing bacteria and EM bacteria, the reaction takes 72 hours to completely metabolize the organic matter and achieve nutrient stabilization, thus forming liquid fertilizer.

6. The preparation method according to claim 1, characterized in that Also includes: Leachate recycling step: The small amount of leachate produced during the fermentation process is transported to the recovery and purification module through a pipeline. Nanobubble aeration technology is used to remove suspended particles in the leachate, and harmful impurities are further removed through biochar filtration. The purified liquid is then returned to the raw material pretreatment and acidification fermentation steps, mixed with new raw materials to participate in the next round of reaction, thus forming an internal closed-loop circulation of liquid fertilizer.

7. The preparation method according to claim 1, characterized in that It also includes the closed-loop integration steps for vegetable cultivation, Supply purified liquid fertilizer directly to the vegetable cultivation system; In the vegetable cultivation system, an IoT-based fertilizer efficiency early warning model is integrated, and leaf spectral analysis and substrate solution real-time monitoring technology are used to collect crop growth status and substrate nutrient data in real time, and compare them with preset fertilizer efficiency standards; Dynamically adjust liquid fertilizer supply and preparation process based on monitoring data; At the same time, the biomass residues and microecological feedback generated during the crop growth process are collected and fed back to the raw material pretreatment step as organic raw materials, thus forming a closed-loop circulation of materials and energy between the fermentation system and the vegetable cultivation system.

8. A closed-loop vegetable cultivation liquid fertilizer system based on mineral-organic composite fermentation, characterized in that: include: Fermentation system, including a multi-stage fermentation tank group, a raw material pretreatment module, and a leachate recovery and purification module; The raw material pretreatment module is used to perform microwave activation and acid hydrolysis treatment on mineral raw materials, and enzymatic hydrolysis treatment on organic raw materials; The multi-stage fermentation tank group includes an acidification fermentation tank, a chelation reaction tank, and a composting stabilization tank, which are used in sequence to start the hydrolysis reaction, promote the chelation reaction between the trace elements released by the minerals and the organic degradation products, and complete the complete metabolism of the organic matter under the continuous oxygen supply and the synergistic action of microorganisms; The leachate recovery and purification module uses nanobubble aeration and biochar filtration technology to purify the leachate produced during the fermentation process and returns the purified liquid to the fermentation system, forming an internal closed-loop circulation; The vegetable cultivation system directly receives liquid fertilizer supplied by the fermentation system, collects biomass residues and microecological feedback generated during crop growth, and feeds them back to the pretreatment module as organic raw materials, realizing a closed-loop circulation of materials and energy; The intelligent control system integrates EC, pH, ORP, and DO sensors and a central control unit. Through the Internet of Things platform, it monitors and transmits data in real time on key parameters in each link of fermentation, leachate recovery, purification, and vegetable cultivation. It also dynamically adjusts process parameters according to preset standards to achieve fertilizer efficiency early warning and process optimization.

9. The system according to claim 8, characterized in that The acidification fermentation tank is equipped with a special agitator to ensure uniform mixing of the reactants; The chelation reaction tank is equipped with an ultrasonic dispersion device to prevent mineral precipitation; The composting and stabilization tank is equipped with a temperature control device and a suitable biofilm carrier.

10. The system according to claim 8, wherein: The intelligent control system comprises: Multi-parameter monitoring unit for real-time data collection of EC, pH, ORP, and DO in fermentation, exudate purification, and vegetable cultivation systems; The central control unit compares the monitoring data with the preset fertilizer efficiency standards and automatically adjusts the process parameters of oxygen supply, temperature, pH value and feeding; The IoT communication module enables wireless data transmission and remote monitoring, while integrating a fertilizer efficiency early warning model based on leaf spectral analysis and real-time monitoring of substrate solution to dynamically optimize liquid fertilizer preparation and supply.

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