Preparation process of tomato straw bio-organic fertilizer reinforced by magnesium modified biochar

Abstract

The present application relates to the technical field of fertilizer composition and its preparation, and discloses a preparation process of magnesium modified biochar reinforced tomato straw bio-organic fertilizer, which comprises the following steps: generating a solid phase carbon base carrier by limiting oxygen pyrolysis of lignocellulose based biomass material, and quickly quenching the carrier in a magnesium salt solution in a hot state, so that magnesium ions are driven into microporous deep parts by using thermodynamic pressure difference; and mixing the obtained modified carrier with an organic fermentation substrate, so as to induce magnesium ions and humic acid to be crosslinked and coordinated at a contact interface, and to self-assemble and construct a mineral-organic complex interface layer with proton response characteristics. The present application adjusts nutrient osmotic pressure by using reversible phase transition of the gel and sol state of the interface layer under the driving of proton concentration, realizes deep anchoring of mineral elements in the carbon base skeleton, effectively solves the problem of poor adhesion of nutrients, and realizes dynamic matching of the nutrient release rate and the physiological demand of crops.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer composition and preparation technology, and particularly relates to a process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer. Background Technology

[0002] Currently, the resource utilization of tomato straw to prepare bio-organic fertilizer is the main way to recycle agricultural waste. In this technical approach, straw biochar is usually used as a nutrient carrier. Mineral elements are loaded through physical blending or impregnation processes to improve the fertilizer's retention performance. However, because the surface of tomato straw biochar is hydrophobic, conventional magnesium salt solutions are constrained by the solid-liquid interfacial tension and have difficulty penetrating deep into the micropores. This interfacial compatibility defect causes mineral components to adhere to the carrier surface in a physically adsorbed state. During the irrigation process of facility agriculture, the poorly attached mineral elements are leached away with water, reducing fertilizer utilization efficiency.

[0003] Industry experts have attempted to enhance impregnation depth using ultrasonic treatment or the addition of surfactants. However, ultrasonic processes incur high equipment energy consumption and maintenance costs, limiting the engineering application of bulk agricultural materials. Furthermore, forced loading by increasing solution concentration often leads to the precipitation and recrystallization of mineral salts at the pore openings during the drying stage, creating a pore-sealing effect that hinders the entry of large organic matrix molecules into the pores. This phenomenon limits the effective utilization of the carrier's internal surface area, causing a mismatch between fertilizer release rates and the physiological needs of the tomato growth cycle. Besides the physical limitations of carrier morphology and impregnation processes, the logical coupling of the process flow and the precise control of release behavior remain insufficient. For example, [the following is an example of an issue related to] authorization announcement number CN11... Chinese invention patent 7323963B discloses a magnesium-modified straw biochar, its preparation method, and its application. The method involves soaking straw in a magnesium salt solution for a long time and then carbonizing it at high temperature. The magnesium element loading is achieved through the pyrolysis process. However, the method of soaking before carbonization or conventional physical soaking is limited by the solid-liquid interfacial tension bottleneck. Magnesium ions are only retained in the shallow surface layer of the carrier. During the carbonization stage, pore crystallization and blockage occur, resulting in low specific surface area utilization. Such patents mainly focus on the static adsorption and removal of phosphorus in water. They lack a dynamic sensing and response mechanism for the crop rhizosphere microenvironment, making it difficult to achieve a logical match between nutrient release rate and crop physiological needs. They cannot solve the problem of ineffective nutrient loss under high-frequency irrigation in field.

[0004] Therefore, the technical problem to be solved by this invention is how to construct a stable fertilizer mixture system, utilize the pressure gradient generated during the pyrolysis stage to build physical adsorption power, and achieve automatic regulation of nutrient release without introducing high costs. Summary of the Invention

[0005] This invention provides a process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer, comprising the following steps: Step S101: Lignocellulose-based biomass material is placed in an oxygen-limited environment for controlled pyrolysis to generate a solid carbon-based carrier; when the solid carbon-based carrier has completed pyrolysis and the temperature drops to the thermodynamic equilibrium transition point of 400℃ to 450℃, it is placed in a magnesium salt solution at a temperature of 15℃ to 25℃ for forced quenching, generating a capillary self-absorption force generated by the thermodynamic negative pressure that drives magnesium ions to migrate into the deep micropores of the solid carbon-based carrier, thus obtaining magnesium-modified biochar. Step S102: Mix plant-derived organic materials with fermentation inoculum and carry out composting and fermentation. Monitor the conductivity of the fermentation material system during the fermentation process. Adjust the replenishment amount of circulating liquid according to the ion concentration fluctuation value fed back by the conductivity to maintain the ion strength of the fermentation material system in the range of 1.2 to 1.8 mS / cm, and obtain an organic fermentation substrate rich in humic acid components. In step S103, the magnesium-modified biochar obtained in step S101 is mixed with the organic fermentation substrate obtained in step S102 at a mass ratio of 1:5 to 1:8. This induces an in-situ coordination crosslinking reaction between magnesium ions in the micropores of the magnesium-modified biochar and humic acid components in the organic fermentation substrate at the contact interface. A mineral-organic complex interface layer with proton-responsive characteristics is self-assembled on the pore surface of the magnesium-modified biochar. Nutrient osmotic pressure is adjusted by the reversible phase transition of the gel-sol layer driven by the proton concentration gradient. Finally, tomato straw bio-organic fertilizer is obtained after drying and granulation.

[0006] Preferably, in step S101, the controlled pyrolysis temperature of the lignocellulose-based biomass material is 450°C to 550°C, and the pyrolysis time is 2h to 4h. Before forced quenching, the residual hydrocarbon gas generated by pyrolysis is used to perform a vapor-phase deposition reaction on the pore wall surface of the solid carbon-based support under the catalysis of magnesium ions to form a carbon nanotube coating. The magnesium salt solution includes magnesium sulfate and magnesium chloride, and the mass ratio of magnesium sulfate to magnesium chloride is 3:1.

[0007] Preferably, in step S102, the ionic strength of the fermentation material system is determined by the following calculation rule: ,in, Represents the ionic strength of the fermentation material system; The first in the fermentation material system The molar concentration of each soluble ionic component; Representing the The charge number of each dissolved ionic component; calculated The deviation between the value and the preset threshold range is used to dynamically adjust the amount of circulating fluid replenished per unit time.

[0008] Preferably, the solid particle size of the organic fermentation substrate obtained in step S102 at the end of composting is 0.5 mm to 2 mm, and the mass ratio of fulvic acid to humic acid in the humic acid component is not less than 2:1.

[0009] Preferably, in step S103, the assembly environment temperature of the mineral-organic complex interface layer is maintained at 35°C to 45°C, and the pH value of the organic fermentation substrate is maintained in the range of 7.5 to 8.2 by adding potassium hydroxide solution to the mixed system, so that magnesium ions can chelate with the carboxyl and hydroxyl groups in the humic acid component until the mineral-organic complex interface layer is transformed into a gel state that blocks nutrients.

[0010] Preferably, in step S103, after mixing, the mixture of magnesium-modified biochar and organic fermentation substrate is subjected to shear field forced coating treatment. The rotation speed of the shear field forced coating treatment is 120 r / min to 200 r / min, and the treatment time is 15 min to 30 min.

[0011] Preferably, the drying process in step S103 adopts a reduced pressure drying method, with a vacuum degree of -0.06MPa to -0.08MPa and a drying temperature maintained at 50°C to 55°C.

[0012] Preferably, after obtaining magnesium-modified biochar in step S101, the method further includes surface rinsing of the magnesium-modified biochar with dilute sulfuric acid at a mass percentage concentration of 1% to 3% until the magnesium ion concentration in the rinsing solution is lower than a preset threshold.

[0013] Preferably, the fermentation agent in step S102 includes Bacillus subtilis, Trichoderma, and Saccharomyces cerevisiae, and the amount of fermentation agent added to the plant-derived organic material is 0.2% to 0.5% by mass.

[0014] Preferably, during the granulation process of the tomato straw bio-organic fertilizer obtained in step S103, the moisture content of the fertilizer particles is monitored; based on the real-time detection value of the moisture content, the extrusion pressure of the granulation equipment is adjusted so that the average compressive strength of the fertilizer particles is not less than 15N.

[0015] Compared with existing technologies, the magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer preparation process of this invention has the following advantages: 1. In the preparation of tomato straw bio-organic fertilizer, the temperature range is controlled during the pyrolysis stage of tomato straw. By adding the hot carbon body in the quasi-steady-state active period into the magnesium salt solution, the capillary self-absorption effect generated by the interfacial thermodynamic pressure difference is induced. This drives the magnesium salt solution to overcome the hydrophobic resistance of the biochar surface and enter the depth of the micropores, thereby achieving deep anchoring of mineral elements inside the biochar skeleton and solving the problem of poor adhesion and easy detachment of nutrients on the carrier surface.

[0016] 2. The mixing process adjusts the ionic strength and pH of the fermentation products to induce magnesium ions precipitated in the biochar pores to undergo in-situ coordination cross-linking with humic acid components in the external matrix at the pore openings, producing an organic mineral complex gel layer with acid-responsive characteristics. Based on the concentration fluctuations of rhizosphere exudates, a reversible phase transition between sol and gel states is generated, achieving a logical match between nutrient release rate and crop physiological needs, and eliminating ineffective nutrient loss caused by irrigation leaching.

[0017] 3. Utilizing the residual hydrocarbon gas at the end of pyrolysis, in-situ carbonization and deposition occur on the inner wall of biochar under the catalysis of magnesium ions, generating a hydrophobic protective layer on the anchored magnesium salt surface. This protective layer, together with the gel sealing layer at the pore opening, forms a synergistic barrier, changing the nutrient release kinetics from surface dissolution to controlled microporous diffusion, thereby improving the structural stability of fertilizer particles under fluctuating moisture conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart of the process for preparing tomato straw bio-organic fertilizer based on thermodynamic quenching and electrical conductivity feedback, as described in this invention. Figure 2 This is a schematic diagram illustrating the evolution of the technical path of deep modification of the carrier and intelligent assembly of the interface in this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0022] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] This invention provides a process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer. It achieves deep implantation of mineral elements through controlled pyrolysis and directional quenching of lignocellulose-based biomass materials. Combined with conductivity feedback adjustment and interface self-assembly technology of the organic fermentation matrix, a mineral-organic complex interface layer with proton-responsive characteristics is constructed. The process mainly consists of four stages: carbon-based carrier preparation, organic fermentation matrix composting, interface self-assembly guidance, and finished product granulation. The nutrient loading and release performance are simultaneously optimized through the coupling of thermodynamic parameters and chemical potential gradients between each stage. To address the problem of poor mineral element adhesion and easy leaching caused by the hydrophobic surface of tomato straw biochar, this invention implements a solid-phase carbon-based carrier preparation and magnesium ion deep anchoring procedure, namely step S101, where tomato straw and other lignocellulose-based biochar are... Cellulose-based biomass is pulverized to 1-3 cm and placed in an oxygen-limited pyrolysis furnace. It is heated to 450-550°C at a heating rate of 15-25°C / min and maintained for 2-4 hours to carbonize the lignocellulose and generate a solid carbon-based carrier. When the solid carbon-based carrier has completed pyrolysis and the temperature drops to the thermodynamic equilibrium transition point of 400-450°C, it is forcibly quenched in a magnesium salt solution maintained at 15-25°C. During this process, the hot gas remaining inside the biochar undergoes rapid cooling and contraction upon contact with the low-temperature liquid, forming a thermodynamic negative pressure inside and outside the micropores. This negative pressure drives the magnesium salt solution to overcome the solid-liquid interfacial tension and generate capillary self-absorption force, causing magnesium ions to migrate into the deep micropores of the solid carbon-based carrier, completing the transformation of mineral elements from surface physical adsorption to anchorage deep within the pores.

[0024] To address the obstacle of unstable interfacial assembly caused by fluctuations in ion concentration in the fermentation material system, this invention implements an organic fermentation substrate control procedure based on conductivity feedback in step S102. Plant-derived organic materials such as tomato straw are mixed with 0.2% to 0.5% by mass of fermentation inoculants, including Bacillus subtilis, Trichoderma, and Saccharomyces cerevisiae. During the composting and fermentation process, the conductivity changes of the fermentation material system are monitored using an online conductivity meter, and the replenishment amount of the circulating liquid is adjusted according to the feedback ion concentration fluctuations to maintain the ionic strength of the fermentation material system between 1.2 and 1.8. Within a certain range, to obtain an organic fermentation substrate rich in flexible chain humic acid components, with ionic strength The determination follows the formula below: ,in: The ionic strength of the fermentation material system; For the first in the system The molar concentration of each soluble ionic component, in units of ; For the first The charge number of each dissolved ionic component; by calculating the... The value is compared with the preset threshold range. If If the value is too high, increase the amount of deionized water supplied. If the value is too low, the discharge of circulating liquid is reduced to ensure that the humic acid molecules participating in the coordination reaction are in an extended state. Based on the physiological magnesium deficiency problem caused by the mismatch between nutrient release rate and crop growth requirements, this invention performs a self-assembly construction procedure for the mineral-organic complex interface layer in step S103. Magnesium-modified biochar and organic fermentation substrate are added to the mixing equipment at a mass ratio of 1:5 to 1:8. The assembly environment temperature is adjusted to 35℃ to 45℃, and potassium hydroxide solution is added to the system to maintain the pH value within the range of 7.5 to 8.2. Under this alkaline environment, the pores of the magnesium-modified biochar... Magnesium ions released from the pores act as a cross-linking source, undergoing multi-point in-situ coordination and cross-linking reactions with the carboxyl and hydroxyl groups of the humic acid components in the external matrix. This results in the self-assembly of a mineral-organic complex interface layer with a thickness of 120 nm to 250 nm on the surface of the biochar pores. Under normal conditions, this layer exhibits a tight gel state to lock in nutrients. When tomato roots secrete organic acids, leading to an increase in the proton concentration in the rhizosphere microenvironment, the protons replace magnesium ions, inducing a reversible phase transition of the interface layer to a sol state. This allows the nutrient osmotic pressure to be adjusted according to the physiological needs of the crop, ensuring that the fertilizer release rate corresponds to the fertilizer requirements of tomato growth.

[0025] When the pH value decreased from 7.8 to 5.2, the measured interface response factor To achieve the quantitative calibration described above, a standard osmotic cell with a diameter of 50 mm was used. A 0.1 mol / L citric acid solution was added dropwise at a step flow rate of 0.02 mL / min using a micro-pump to simulate the proton secretion process of tomato roots. The system used a 16-bit analog-to-digital converter to acquire the raw voltage signal from the osmotic pressure sensor in real time, ranging from 0.5 mV to 4.5 mV, and mapped it to an interfacial osmotic pressure value with a resolution of 0.01 MPa. The change in osmotic pressure was recorded synchronously for every 1.0e-5 mol / L increase in proton concentration in the simulated environment, ensuring the reproducibility of the interfacial response factor within a linear range of 0.85 to 0.95. The interfacial layer transitioned from a gel state to a sol state in 18.5 min, confirming that the interfacial layer exhibits reversible phase transition characteristics between gel and sol states under proton concentration drive, achieving dynamic matching between nutrient release rate and crop physiological needs. To improve the stability of fertilizer granules under irrigation conditions, a pore wall carbon nanotube coating was incorporated into the preparation process. The enhanced vapor deposition process utilizes low-molecular-weight hydrocarbon residues generated during pyrolysis, catalyzed by magnesium ions, to perform vapor deposition on the pore walls of a solid carbon-based carrier before forced quenching. This forms a carbon nanotube coating, which acts as a hydrophobic protective layer in synergy with the external complexing interface layer. This transforms the nutrient release kinetics from surface dissolution to a controlled microporous diffusion mode, maintaining the integrity of the particle structure during the 120-150 day fertilizer effect period and preventing premature crop senescence caused by interrupted nutrient release in the later stages. The final product is obtained through a vacuum drying and extrusion granulation process. The mixed material is dried in an environment with a vacuum degree of -0.06MPa to -0.08MPa and a temperature of 50℃ to 55℃. The mixture is then extruded using a granulator. During granulation, the moisture content of the particles is monitored in real time, and the extrusion pressure is adjusted based on the measured moisture value to ensure that the average compressive strength of the resulting fertilizer particles is not less than 15N. This yields a tomato straw bio-organic fertilizer product with deep anchoring effect and acid-responsive gating characteristics.

[0026] Example 1: In a tomato greenhouse under continuous cropping conditions, the soil exhibits secondary salinization due to long-term excessive fertilization. Furthermore, during the peak fruit-setting period, the soil undergoes frequent irrigation more than twice daily. This situation exacerbates the problem, given the typical soil conditions in the tomato growing environment. The magnesium content was between 7.8 and 8.1. Traditional magnesium fertilizers have a high leaching rate under heavy irrigation, leading to interveinal chlorosis in tomato plants in the later stages due to physiological magnesium deficiency. Magnesium-modified biochar-fortified tomato straw bio-organic fertilizer, prepared using the aforementioned process, was applied to the soil. The solid carbon-based carrier was then subjected to a 500-ton leaching process. The instantaneous quenching after pyrolysis anchors highly loaded magnesium ions deep within the micropores, and the pore wall surface is covered with a carbon nanotube coating formed by vapor deposition. The physical structure generated by this preparation process, together with the self-assembled mineral-organic complex interface layer, constructs a physical and chemical barrier for the slow release of nutrients. When tomatoes enter the critical period of simultaneous vegetative and reproductive growth, the roots secrete organic acids, mainly malic acid and citric acid, into the rhizosphere soil, leading to an increase in the proton concentration in the rhizosphere microenvironment and localized... When the value drops below 5.5, the mineral-organic complex interface layer senses the proton signal and undergoes a phase transition. The humic acid-magnesium coordination network, which was originally in a tight gel state, dissociates under the action of proton replacement and transforms into a highly permeable sol state, so that the magnesium ions stored deep in the micropores of the solid carbon-based carrier are released in a directional manner according to the intensity of plant physiological metabolism.

[0027] During this dynamic release process, the controlled fluctuations in the ionic strength of the fermentation material system follow the following mathematical constraints: ,in: The ionic strength of the fermentation material system; For the first in the system The molar concentration of each soluble ionic component, in units of ; For the first The charge number of each dissolved ionic component is determined by controlling the ionic strength between 1.2 and 1.8. Within this range, the flexible segments of humic acid molecules form a stable three-dimensional cross-linked network with magnesium ions, thereby maintaining a stable nutrient gradient output when subjected to intense external irrigation water scouring, reducing ineffective nutrient leaching. After 150 days of monitoring throughout the tomato's entire growth period, the magnesium content of tomato leaves remained above 0.4%, and the yield per tomato plant increased by 20% to 25% compared to conventional compound fertilizers with the same amount of magnesium. Furthermore, the compressive strength of the fertilizer granules remained at a level of no less than 15N throughout the entire cycle, achieving a synergistic match between mineral element supply and the physiological needs of tomato rhizosphere. Soil electrical conductivity showed a downward trend after the harvest period.

[0028] Example 2: To verify the mineral element retention capacity and acid response release accuracy of magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer under simulated high-frequency irrigation conditions for greenhouse vegetables, a simulated soil column test platform equipped with a fully automatic peristaltic pump, in-situ micro-displacement sensor, and inductively coupled plasma atomic emission spectrometer was used. The temperature control accuracy of the test environment was set to ±0.5°C. And introduce a mass concentration of 50 Using calcium ion solution as a background competing ion perturbation source, a system based on ion strength was established. The feedback interface layer stability assessment method, among which the key parameter is ionic strength The setting follows a synergistic trade-off between the spatial conformational extension of humic acid molecules and the density of multi-site coordination crosslinking, when the ionic strength of the fermentation material system... Between 1.2 and 1.8 Within this range, the resulting electrostatic shielding effect inhibits the disordered aggregation of humic acid molecules, while simultaneously causing exposed carboxyl functional groups to collide with magnesium ions within the micropores of the solid-phase carbon-based support. To verify the engineering basis for this working window, the experiment set an ion strength... They are 0.8 respectively. 1.5 and 2.2 The gradient groups were determined and used as experimental evidence to reveal the performance inflection point.

[0029] During the simulated irrigation flushing test, fertilizer granules were placed in the center of a soil column filled with standard quartz sand, at a depth of 10... Simulated irrigation water was injected in a circulating manner at a flow rate of [missing information], and bottom leachate was collected at 24-hour intervals. The leaching stability of the fertilizer was characterized by measuring the cumulative mass concentration of magnesium ions in the leachate. At the 72nd hour of the irrigation cycle, a concentration of 0.05 [missing information] was instantaneously injected into the top of the soil column. Citric acid solution was used to simulate the organic acid secretion signal of tomato roots during the peak period of nutrient demand. The dissociation rate and nutrient osmotic pressure of the mineral-organic complex interface layer under proton triggering were observed. The original input parameters, key intermediate feature values ​​and final judgment results recorded during the experiment are shown in Table 1.

[0030] Table 1: Comparison of Fertilizer Stability and Response under Different Ionic Strength Regulation According to the test results in Table 1, when the ionic strength Between 1.2 and 1.8 Within the specified range, the retention rate of magnesium remained stable at over 80%, and exhibited a phased release characteristic after acid signal intervention, indicating that the mineral-organic complex interface layer formed a kinetic barrier on the surface of the solid carbon-based support; analysis of the deviation group data revealed that when the ionic strength... Decreased to 0.85 At this time, due to the electrostatic repulsion between humic acid molecules, the interfacial crosslinking density decreases, and the magnesium retention rate declines. Meanwhile, when the ionic strength... Rising to 2.24 Afterwards, although the leaching stability was improved, the response time of acid-induced release was extended to 185.6 min, resulting in response passivation. This verified that the defined parameter range is the working window for balancing the retention effect and response sensitivity. Furthermore, the data comparison with the missing group confirmed that the forced quenching procedure in step S101 provided deep anchoring power for magnesium ions. The generated thermodynamic negative pressure enabled mineral elements to establish a nutrient reserve zone deep within the solid carbon-based carrier framework, achieving a logical match between the fertilizer release curve and the physiological needs of crops.

[0031] Example 3: This example combines Figures 1 to 2 The preparation process of a magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer is described, such as... Figure 1 As shown, two raw materials are processed in parallel. One process inputs lignocellulose-based biomass raw materials into an oxygen-limited controlled pyrolysis stage, generating a solid carbon-based carrier through temperature control. The carrier then enters a forced quenching stage, where it is immersed in a magnesium salt solution. Magnesium ions are driven to migrate using thermodynamic negative pressure to obtain magnesium-modified biochar as intermediate product A. The other process inputs plant-derived organic materials and fermentation agents as raw materials and performs a composting and fermentation process. During this process, a conductivity feedback regulation mechanism is introduced to maintain the ionic strength within the range of 1.2 to 1.8 mS / cm by adjusting the circulating liquid replenishment, thereby obtaining intermediate product B, which is rich in humic acid and is an organic fermentation substrate. Intermediate product A and intermediate product B are mixed at a mass ratio of 1:5 to 1:8 and cross-linked in situ to induce a contact interface reaction. This process constructs proton-responsive characteristics and regulates nutrient osmotic pressure in the self-assembly stage of the mineral-organic complex interface layer. Finally, after drying and granulation, tomato straw bio-organic fertilizer is obtained.

[0032] like Figure 2 As shown, the technical path of this preparation process evolves sequentially from top to bottom. It performs deep modification of the carrier, achieves deep anchoring of magnesium ions through controlled pyrolysis temperature and thermodynamic negative pressure, followed by precise fermentation of the matrix. It relies on online conductivity feedback to maintain steady-state ion strength and directional composting of humic acid, and carries out intelligent interface assembly. It constructs a mineral organic complex layer through in-situ coordination crosslinking and forms a proton-responsive gating mechanism. On this basis, it performs structural reinforcement molding, which includes vapor deposition nanocoating, shear forced coating and depressurized drying granulation steps, and finally obtains magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer.

[0033] Example 4: In an industrial production scenario for processing tomato planting waste, to address the drift in nutrient slow-release curves caused by fluctuations in the coating thickness within the micropores of the solid carbon-based carrier, process parameters were determined by executing a preparation procedure for the carbon nanotube coating on the pore walls. Low-molecular-weight hydrocarbon gas with a carbon content of not less than 1.5% generated during the pyrolysis stage was used as the carbon source, and the temperature was maintained at 480°C. Up to 520 In the sealed reaction chamber, at 0.5 A constant flow rate of hydrocarbon gas is introduced, and the average thickness of the carbon nanotube coating... The mapping relationship between the parameters and the deposition parameters follows the following formula: ,in, The average thickness of the carbon nanotube coating is given in units of 1000 m². ; For the interface deposition rate, at 480 Up to 520 The value was confirmed to be 0.015 within the temperature range. ; The duration of vapor deposition is expressed in units of... By extending the deposition time The time was set to 1200s to achieve a target thickness of 18nm for the resulting carbon nanotube coating. This coating forms a hydrophobic protective layer on the surface of the pore walls of the solid carbon-based carrier, which provides physical constraint for internally anchored magnesium ions under conditions of fluctuating moisture.

[0034] To determine the accuracy of the response of the mineral-organic complex interface layer to the rhizosphere acid signal in tomato, the humic acid component in the organic fermentation substrate was determined by potential titration. The maximum carboxyl loading capacity was 8.0, and the measured carboxyl loading capacity was 4.2. At that time, the mixing mass ratio in step S103 is determined according to the coordination ratio of magnesium ions to carboxyl groups of 1:2 to ensure the interfacial response factor within the system. The interface response factor is in the linear region of 0.85 to 0.95. The definition is as follows: ,in: It is the interface response factor, used to characterize the sensitivity of the mineral-organic complex interface layer to proton strength; The change in interfacial osmotic pressure, in units of ; This represents the change in proton concentration in the rhizosphere microenvironment, expressed in units of... In a set of controlled trials, when When the value decreased from 7.8 to 5.2, the measured value was... The value is 0.88, at which point the phase transition time of the mineral-organic complex interface layer from the gel state to the sol state is 18.5 min.

[0035] The resulting tomato straw bio-organic fertilizer product demonstrated a stable nutrient supply capacity when facing the high nutrient demand pressure during the vigorous reproductive growth period of tomatoes. After 120 days of field observation, the effective magnesium concentration in the soil fluctuated within a range of 25%. Up to 35 Through the logical coupling between the carbon nanotube coating formed by vapor deposition and the mineral-organic complex interface layer formed by self-assembly, the woody fiber framework of tomato straw is transformed into a nutrient carrier with active sensing function, realizing efficient retention and on-demand release of mineral elements. Moreover, the fertilizer particles maintain an intact skeletal structure after the harvest period. This process, through quantitative control of deposition rate and proton response factor, transforms the material components into a fertilizer mixture with acid-responsive gating characteristics, verifying the principle-driven nature and reproducibility of setting key parameters in the preparation process.

[0036] Example 5: In a production scenario involving large-scale processing of tomato straw from different planting areas, to suppress the interference of fluctuations in the intrinsic physicochemical properties of the material on the stability of mineral element loading, adjustment steps were implemented for the solid-phase carbon-based carrier preparation stage. The mass fraction of lignocellulose in the tomato straw raw material was determined using an analyzer with a testing accuracy of not less than 0.01%. Based on the measurements Adjusting the material residence time in the oxygen-limited pyrolysis furnace This stabilizes the specific surface area of ​​the solid carbon-based support at a certain level. to Within the specified range, the pore volume per unit mass of the pyrolysis products was determined using an analyzer. Based on this, the set mass concentration of the magnesium salt solution is determined. The mass concentration is determined according to the following formula: ,in: This represents the mass concentration of the magnesium salt solution, in units of... ; The target magnesium element retention density is located at to Within the range; This is the pore filling correction factor, with a value ranging from 0.85 to 0.92; The measured pore volume per unit mass of the solid carbon-based support is given in units of... .

[0037] By forcibly quenching Adjust to This allows magnesium ions to migrate deep into the micropores under the generated thermodynamic negative pressure, thus ensuring the stability of the magnesium ion load distribution on the resulting solid carbon-based support when faced with fluctuations in raw material prices.

[0038] When the system encounters organic materials with different degrees of decomposition, it executes a process based on the carbon-to-nitrogen ratio. With initial conductivity The adjustment steps determine the amount of fermentation agent to be added, and the initial concentration of the mixture is measured using an analyzer. The initial value was adjusted by supplementing with urea or sawdust. Adjust to a baseline range of 25 to 30 to obtain the initial conductivity of the fermentation material system at the start of step S102. ,in accordance with The mass fraction of the fermentation agent is determined by the deviation from the target ionic strength. This allows the carboxyl group content of humic acid molecules to reach a certain level after 48 hours of fermentation. In the drying process before granulation, the vacuum level is controlled at -0.07. The moisture loss rate of the material was monitored in real time under reduced pressure. ,when The drying process is terminated when the moisture content drops below 0.1% per hour and the measured moisture content is 12.5%. The resulting material is then conveyed to the granulator, where the extrusion pressure is controlled at 8.5 based on the pellet forming pressure feedback logic. Up to 10.2 The final fertilizer granules produced have an average compressive strength of 18.6 N and a strength of 25 N. The saturated moisture absorption rate under the environment is less than 8%, which realizes the stability compensation of the material's initial state fluctuation in the preparation process.

[0039] Example 6: Under the condition of customized fertilizer production for different tomato genotypes, an adjustment program for the phase transition threshold of the mineral-organic complex interface layer was executed, and the rhizosphere proton secretion rate of the target tomato variety during the peak fruiting period was measured using an analyzer. And based on the measurements Determine the target crosslinking density coefficient of the complex interface layer ,in The determination follows the formula below: ,in, The target crosslinking density coefficient of the interface layer ranges from 0.75 to 0.85. The proton secretion rate of the target variety, in units of ; The baseline proton secretion rate is determined as a constant at a preset ambient temperature, and the unit is _____. ; The interface response adjustment factor ranges from 0.92 to 1.15; the dropping rate of the potassium hydroxide solution is adjusted to 5.2 during the mixing stage in step S103. This caused the resulting mineral-organic complex interface layer to undergo a phase transition when faced with a proton triggering signal of a specific intensity, and the matching state of magnesium distribution with crop growth cycle was confirmed in soil testing after harvest.

[0040] When the system faces batch conditions of organic fermentation substrates with different humic acid component activities, it executes a process based on the real-time conductivity change rate. The termination determination procedure determines the mixing time, and the conductivity of the system is collected in real time in the mixing device in step S103. The data is obtained by calculating the change in conductivity over adjacent sampling periods to determine the rate of change at the current moment. When measured For 300 seconds, the change remains below the preset threshold. When the pH of the system stabilizes between 7.8 and 8.1, the coordination cross-linking reaction between magnesium ions and humic acid is considered to have reached equilibrium, and the mixing step is terminated. Before the material is transported to the subsequent granulation stage, the initial osmotic resistance of the resulting mineral-organic complex interface layer is measured using an osmometer. and in When the soil moisture content is within the range of 0.15MPa to 0.22MPa, the finished product granules are granulated. The final fertilizer granules maintain the evolution of the nutrient release gradient when faced with fluctuations in soil moisture, and achieve stability compensation of the preparation process between different batches.

[0041] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer, characterized in that, Includes the following steps: Step S101: Lignocellulose-based biomass material is placed in an oxygen-limited environment for controlled pyrolysis to generate a solid carbon-based carrier; when the solid carbon-based carrier has completed pyrolysis and the temperature drops to the thermodynamic equilibrium transition point of 400℃ to 450℃, it is placed in a magnesium salt solution at a temperature of 15℃ to 25℃ for forced quenching, generating a capillary self-absorption force generated by the thermodynamic negative pressure that drives magnesium ions to migrate into the deep micropores of the solid carbon-based carrier, thus obtaining magnesium-modified biochar. Step S102: Mix plant-derived organic materials with fermentation inoculum and carry out composting and fermentation. Monitor the conductivity of the fermentation material system during the fermentation process. Adjust the replenishment amount of circulating liquid according to the ion concentration fluctuation value fed back by the conductivity to maintain the ion strength of the fermentation material system in the range of 1.2 to 1.8 mS / cm, and obtain an organic fermentation substrate rich in humic acid components. In step S103, the magnesium-modified biochar obtained in step S101 is mixed with the organic fermentation substrate obtained in step S102 at a mass ratio of 1:5 to 1:

8. This induces an in-situ coordination crosslinking reaction between magnesium ions in the micropores of the magnesium-modified biochar and humic acid components in the organic fermentation substrate at the contact interface. A mineral-organic complex interface layer with proton-responsive characteristics is self-assembled on the pore surface of the magnesium-modified biochar. Nutrient osmotic pressure is adjusted by the reversible phase transition of the gel-sol layer driven by the proton concentration gradient. Finally, tomato straw bio-organic fertilizer is obtained after drying and granulation.

2. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, In step S101, the controlled pyrolysis temperature of the lignocellulose-based biomass material is 450°C to 550°C, and the pyrolysis time is 2h to 4h. Before forced quenching, the residual hydrocarbon gas generated by pyrolysis is used to perform a vapor-phase deposition reaction on the pore wall surface of the solid carbon-based support under the catalysis of magnesium ions to form a carbon nanotube coating. The magnesium salt solution includes magnesium sulfate and magnesium chloride, and the mass ratio of magnesium sulfate to magnesium chloride is 3:

1.

3. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, In step S102, the ionic strength of the fermentation material system is determined by the following calculation rules: ,in, Represents the ionic strength of the fermentation material system; The first in the fermentation material system The molar concentration of each soluble ionic component; Representing the The charge number of each dissolved ionic component; calculated The deviation between the value and the preset threshold range is used to dynamically adjust the amount of circulating fluid replenished per unit time.

4. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, The solid particle size of the organic fermentation substrate obtained in step S102 at the end of composting is 0.5 mm to 2 mm, and the mass ratio of fulvic acid to humic acid in the humic acid component is not less than 2:

1.

5. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, In step S103, the assembly environment temperature of the mineral-organic complex interface layer is maintained at 35°C to 45°C. The pH value of the organic fermentation substrate is maintained in the range of 7.5 to 8.2 by adding potassium hydroxide solution to the mixed system, so that magnesium ions can chelate with the carboxyl and hydroxyl groups in the humic acid component until the mineral-organic complex interface layer is transformed into a gel state that blocks nutrients.

6. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, In step S103, after mixing, the mixture of magnesium-modified biochar and organic fermentation substrate is subjected to shear field forced coating treatment. The rotation speed of the shear field forced coating treatment is 120 r / min to 200 r / min, and the treatment time is 15 min to 30 min.

7. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, The drying process in step S103 adopts a reduced pressure drying method, with a vacuum degree of -0.06MPa to -0.08MPa and a drying temperature maintained at 50℃ to 55℃.

8. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, After obtaining magnesium-modified biochar in step S101, the method further includes surface rinsing of the magnesium-modified biochar with dilute sulfuric acid at a mass percentage concentration of 1% to 3% until the magnesium ion concentration in the rinsing solution is lower than a preset threshold.

9. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, The fermentation agents in step S102 include Bacillus subtilis, Trichoderma, and Saccharomyces cerevisiae, and the amount of fermentation agents added to the plant-derived organic material is 0.2% to 0.5% by mass.

10. The process for preparing magnesium-modified biochar-enhanced tomato straw bio-organic fertilizer according to claim 1, characterized in that, During the granulation process of the tomato straw bio-organic fertilizer obtained in step S103, the moisture content of the fertilizer particles is monitored; based on the real-time detection value of the moisture content, the extrusion pressure of the granulation equipment is adjusted so that the average compressive strength of the fertilizer particles is not less than 15N.

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