A system for combined carbon sequestration and soil improvement using biogas slurry and biochar

Abstract

This invention discloses a system for combined carbon sequestration and soil improvement using biogas slurry and biochar, relating to the fields of soil improvement and carbon fixation technology. The system includes: calculating the pore mineralization throat ring index by measuring the short-range elution release equivalent, total load equivalent, and connectivity ratio of the composite particles; adjusting the total load equivalent based on this index to obtain the true effective exchange load of the composite particles; and finally calculating the application rate per unit area based on the unit area requirement equivalent of the target plot, using this to guide field application. This invention achieves adaptive quantitative fertilization, effectively ensuring the stability of carbon sequestration and soil improvement effects under complex conditions.

Description

Technical Field

[0001] This invention relates to the field of soil improvement and carbon fixation technology, and in particular to a system for carbon fixation and soil improvement using a combination of biogas slurry and biochar. Background Technology

[0002] With the continuous advancement of dual carbon goals, the resource utilization of agricultural waste and the enhancement of soil carbon sequestration function have become important research directions. Biochar, due to its highly aromatic structural characteristics, has extremely high chemical stability and can preserve carbon elements for a long time after being applied to the soil, making it an effective way to achieve carbon sequestration in agriculture. On the other hand, the biogas slurry produced by large-scale livestock and poultry farming is rich in readily available nutrients such as nitrogen, phosphorus, and potassium, as well as a large amount of soluble organic matter. Combining biogas slurry with biochar to prepare solid fertilizer or soil conditioner can not only utilize the porous structure of biochar to adsorb and slowly release nutrients in biogas slurry, reducing the transportation costs and environmental risks of directly returning biogas slurry to the field, but also further improve carbon stability through the formation of organic-inorganic complexes. However, in the actual preparation and application of biogas slurry and biochar composite particles, there are significant differences in solute mobility inside and outside the pores of the composite particles and a preference for solid-phase interface nucleation. This leads to mineral precipitation being preferentially generated at the pore openings or throats of the composite particles, thus forming annular precipitation zones. A small amount of mineral precipitation located at the pore throat will cause a nonlinear decay in the mass transfer and conductivity of the particle pores, turning the pore network from a connected porous medium into an inlet-restricted medium, resulting in a valve effect.

[0003] Current technologies, when guiding field application, generally adopt experience-based fixed application rate standards, such as directly specifying a certain number of tons of composite material to be applied per hectare. This one-size-fits-all application method completely ignores the pore throat flow restriction phenomenon that occurs in different batches of composite particles and under real soil ion backgrounds. Due to the pore throat restriction, the nutrients and carbon sources loaded inside the composite particles cannot be smoothly exchanged and released with the outside environment in a short distance. This results in a significant structural deviation between the theoretical total load of the particles and the actual exchangeable effective load. This deviation leads to a mismatch between carbon sequestration performance and nutrient supply. Ultimately, this causes unpredictable and drastic fluctuations in the soil improvement and carbon sequestration effects of existing composite materials when applied under different plot conditions, making it difficult to achieve stable and quantifiable agricultural ecological benefits. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies where mineralization and precipitation at the pore openings of composite particles form throat rings that restrict pore size, resulting in a significant deviation between the theoretical total load of the particles and the actual exchangeable effective load. This leads to unpredictable fluctuations in carbon sequestration and soil improvement effects under different conditions when using a fixed application rate. The invention proposes a system that utilizes biogas slurry and biochar for combined carbon sequestration and soil improvement.

[0005] To address the problems existing in the prior art, the present invention adopts the following technical solution: A system for combined carbon sequestration and soil improvement using biogas slurry and biochar includes: The basic parameter measurement module is used to obtain composite particles prepared from biogas slurry and biochar, and to measure the short-range elution release equivalent, total load equivalent, and connectivity ratio of the composite particles. The core index calculation module is used to calculate the orifice mineralization throat ring index based on short-range elution release equivalent, total load equivalent, and connectivity ratio. The effective load correction module is used to recalculate and correct the total load equivalent based on the orifice mineralization throat ring index to obtain the effective exchange load. An adaptive application decision module is used to obtain the unit area demand equivalent of the target plot, divide the unit area demand equivalent by the effective exchange load to obtain the unit area application amount, and apply the composite particles to the target plot according to the unit area application amount.

[0006] Preferably, the composite particles prepared from biogas slurry and biochar include: Biochar is produced by pyrolysis of agricultural waste under anaerobic conditions. Pre-treatment of biogas slurry to remove suspended solids; The biochar and pretreated biogas slurry are mixed at a set mass-volume ratio, and after shaking and settling, they are dried to obtain composite particles.

[0007] Preferably, obtaining the short-range elution release equivalent of the composite particles includes: A set mass of composite particles is added to a set volume of medium liquid. After acting under fixed stirring conditions for a fixed time window, the supernatant is obtained by filtration. The equivalent concentration of the target element in the supernatant is detected and converted according to the set volume of the medium liquid to obtain the short-range elution release equivalent.

[0008] Preferably, obtaining the total loading equivalent of the composite particles includes: Take a composite particle of the same mass as the set mass, and after digestion or extraction, determine the total measurable equivalent of the composite particle. Use the total measurable equivalent as the total load equivalent.

[0009] Preferably, obtaining the connectivity ratio of the composite particles includes: The composite particles are packed into a particle column of fixed geometric size, and the equivalent conductivity or equivalent diffusion index of the particle column is measured. Take biochar of the same particle size distribution as the composite particles and that has not undergone biogas slurry composite treatment, load it and measure the benchmark index; The connectivity ratio is obtained by comparing the equivalent conduction index or equivalent diffusion index with the baseline index.

[0010] Preferably, the orifice mineralization throat ring index is calculated based on the short-range elution release equivalent, the total load equivalent, and the connectivity ratio, including: Subtracting the connectivity ratio from 1 yields the connectivity attenuation factor. Calculate the ratio of short-range elution release equivalent to total load equivalent, subtract the ratio from 1, and multiply the difference by the connectivity attenuation factor to obtain the orifice mineralization throat ring index.

[0011] Preferably, the total load equivalent is adjusted based on the orifice mineralization throat ring index to obtain the effective exchange load, including: Subtract the orifice mineralization throat ring index from 1 to obtain the correction coefficient; Multiply the total load equivalent by the correction factor to obtain the effective exchange load.

[0012] Preferably, applying the composite granules to the target plot according to the unit area application rate includes: The compound granules are applied to the surface soil of the target plot at the specified rate per unit area, and the plot is then tilled and mixed to a depth of 15 to 20 centimeters.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention innovatively constructs a pore mineralization throat ring index by obtaining the short-range elution release equivalent, total load equivalent, and connectivity ratio of composite particles. This index accurately quantifies the degree of pore throat restriction caused by pore mineralization precipitation during the preparation and application of composite particles, and can directly reflect the attenuation of mass transfer and conductivity caused by the transformation of the pore network into an inlet-restricted medium. Based on this index, the total load equivalent is converted and corrected, and the ineffective part that cannot be released due to physical blockage is successfully removed, thereby obtaining the effective exchange load that the composite particles can truly exchange with the external environment in a short range.

[0014] 2. This invention calculates the effective exchange load and combines it with the actual unit area demand equivalent of the target plot to calculate an adaptive unit area application rate, which guides the final field tillage application operation. This fundamentally eliminates the nutrient and carbon source supply mismatch problem caused by the structural deviation between the theoretical total load of particles and the actual exchangeable amount. This ensures that each material application can accurately meet the actual needs of the target soil, effectively guaranteeing the high stability and predictability of the combined carbon fixation and soil improvement effects of biogas slurry and biochar under different preparation batches and complex soil backgrounds. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a functional module diagram of a system for combined carbon sequestration and soil improvement using biogas slurry and biochar, provided as an embodiment of the present invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Example: This example provides a system for combined carbon sequestration and soil improvement using biogas slurry and biochar. See [link to example]. Figure 1 Specifically, including: The basic parameter measurement module is used to obtain composite particles prepared from biogas slurry and biochar, and to measure the short-range elution release equivalent, total load equivalent, and connectivity ratio of the composite particles. The core index calculation module is used to calculate the orifice mineralization throat ring index based on short-range elution release equivalent, total load equivalent, and connectivity ratio. The effective load correction module is used to recalculate and correct the total load equivalent based on the orifice mineralization throat ring index to obtain the effective exchange load. An adaptive application decision module is used to obtain the unit area demand equivalent of the target plot, divide the unit area demand equivalent by the effective exchange load to obtain the unit area application amount, and apply the composite particles to the target plot according to the unit area application amount.

[0018] In an embodiment of the present invention, composite particles prepared from biogas slurry and biochar are obtained, and the composite particles are measured to obtain their short-range elution release equivalent, total loading equivalent, and connectivity ratio, specifically including: Rice straw was selected as agricultural waste. First, the rice straw was cleaned to remove impurities such as stones and mud. Then, it was shredded into 2-3 cm pieces using a hammer mill. The shredded rice straw pieces were evenly spread into a tubular pyrolysis furnace with an inner diameter of 10 cm and a length of 50 cm. The furnace door was closed, and nitrogen gas was introduced at a flow rate of 2 liters per minute. Nitrogen gas was continuously purged for 15 minutes to completely remove air from the furnace and maintain an oxygen-deficient environment. Then, the heating system of the tubular pyrolysis furnace was started to heat the furnace. The temperature was slowly increased to 550℃ at a rate of 5℃ per minute, and then kept at this temperature for 1.5 hours for pyrolysis. Nitrogen gas was continuously introduced during the pyrolysis process to maintain an oxygen-deficient state. After the pyrolysis was completed, heating was stopped, the nitrogen gas supply was turned off, and the product in the furnace was allowed to cool naturally to room temperature. The cooled pyrolysis product was taken out and put into a hammer mill for crushing again. The screen aperture was set to 2 mm. After crushing, it was screened through a standard sieve to obtain biochar with a particle size of 0.5 to 2 mm. The screened biochar was placed in a desiccator for later use.

[0019] Collect biogas slurry produced by anaerobic fermentation in large-scale pig farms. The total solids content of this biogas slurry should be controlled at 5%-8%, with a total nitrogen content ≥1500 mg / L and a total phosphorus content ≥300 mg / L. Slowly pour the biogas slurry into a corrosion-resistant sedimentation tank and let it stand for 24 hours at room temperature (25-28℃) to allow suspended particles to settle to the bottom. Then, use a corrosion-resistant pump to extract the clarified biogas slurry from the top of the sedimentation tank and filter it through a 100-mesh sieve. During filtration, gently scrape the sieve surface with a glass rod continuously to prevent clogging and remove any remaining fine suspended matter, completing the pretreatment of the biogas slurry. Take the prepared biochar and the pretreated clarified biogas slurry and add them to a mixing tank equipped with a constant-temperature oscillation function at a mass-to-volume ratio of 1:8. Start the oscillation device of the mixing tank and adjust the oscillation speed to 150 rpm. At 28℃... Under constant temperature conditions, the mixture is continuously shaken for 3 hours to ensure thorough contact and mixing of biochar and biogas slurry. After shaking, the shaking is stopped, and the temperature inside the mixing tank is maintained at 28°C. The mixture is then allowed to stand and mature for 18 hours to allow nutrients such as nitrogen, phosphorus, and potassium from the biogas slurry, as well as organic matter, to fully penetrate and be loaded into the porous structure of the biochar. After maturation, the mixture is removed from the mixing tank and evenly spread on a stainless steel tray. The tray is then placed in a constant temperature drying oven, and the oven temperature is adjusted to 50°C. The mixture is dried at low temperature under normal pressure. During the drying process, the mixture is gently turned over with a scraper every hour to ensure uniform drying. The mixture is weighed every 2 hours until the difference between two consecutive weighings does not exceed 0.1 grams, thus achieving constant weight determination. After drying, the product is removed, gently pulverized with a pulverizer, and then screened through a standard sieve to remove any lumps. The final product is a biogas slurry and biochar composite granule with uniform particle size and loose texture.

[0020] Specific Examples of Preparation of Biogas Slurry and Biochar Composite Particles It should be noted that, in this embodiment, agricultural waste refers to organic waste generated during agricultural production that can be used to prepare biochar; specifically, rice straw is selected in this embodiment. A tubular pyrolysis furnace refers to a tubular heating device used to achieve pyrolysis of solid materials under controlled temperature and atmosphere, specifically for the anaerobic pyrolysis of agricultural waste to produce biochar. A constant-temperature vibrating stirring tank refers to a container with constant temperature control and vibrating stirring functions, used for the thorough mixing of biochar and biogas slurry. A constant-temperature drying oven refers to equipment that can maintain a constant temperature for low-temperature drying of materials. Constant weight refers to the mass of the material measured twice consecutively during the drying process. The difference reaching the specified range indicates that the material is completely dry; a 100-mesh sieve refers to a standard sieve with 100 holes per inch, used to filter and remove fine suspended solids from the biogas slurry; biochar refers to the solid product obtained after anaerobic pyrolysis of agricultural waste, with a particle size controlled between 0.5 and 2 mm, used to load nutrients and organic matter in the biogas slurry; biogas slurry refers to the fermentation waste liquid generated by anaerobic fermentation projects in large-scale pig farms, which is used to combine with biochar after pretreatment to remove suspended solids; composite particles refer to the solid particle product obtained after mixing, shaking, static maturation, and drying of biochar and pretreated biogas slurry.

[0021] The prepared composite particles were weighed on an electronic balance with an accuracy of 0.001 g. The desired mass of composite particles was obtained and slowly placed into a 500 ml beaker. A predetermined volume of medium was then precisely measured using a graduated cylinder and slowly poured into the beaker containing the composite particles, ensuring complete immersion. A 10 mm diameter polytetrafluoroethylene (PTFE) stir bar was added to the beaker, which was then placed on a magnetic stirrer. The stirrer speed was adjusted to 200 rpm, and the stirring temperature was maintained at a constant 25°C. This stirring was continued for a fixed time window of 2 hours. During the stirring process, the inner wall of the beaker was gently scraped with a glass rod every 30 minutes to prevent the composite particles from adhering to the inner wall and affecting the elution effect. After the fixed time window, the magnetic stirrer was stopped. Stir the mixture and slowly pour it into a funnel lined with qualitative filter paper. Place another clean 500 mL beaker below the funnel and filter using a reduced pressure filtration method. Maintain a uniform decompression rate during filtration to avoid damaging the filter paper and causing impurities to enter. After the mixture has been completely filtered, collect the supernatant in the beaker below the funnel and transfer it to a volumetric flask to bring it to the set volume. Then, use ultraviolet spectrophotometry to detect the inorganic nitrogen equivalent concentration in the supernatant and the molybdenum antimony colorimetric method to detect the inorganic phosphorus equivalent concentration in the supernatant. Record the measured inorganic nitrogen equivalent concentration and inorganic phosphorus equivalent concentration values ​​respectively. Add the measured inorganic nitrogen equivalent concentration and inorganic phosphorus equivalent concentration to obtain the target element equivalent concentration. Then multiply the target element equivalent concentration by the set volume of the medium liquid. Through this conversion method, the short-range elution release equivalent of the composite particles is finally obtained.

[0022] It should be noted that, in this embodiment, the set mass refers to the mass of the composite particles after precise weighing, the set volume refers to the volume of the medium liquid after precise measurement, the fixed stirring conditions are constant stirring speed, stirring temperature and stirring method, the fixed time window is the preset elution time, the target element equivalent concentration is the sum of the concentrations of inorganic nitrogen and inorganic phosphorus in the supernatant, the short-range elution release equivalent is the total amount of nutrients that the composite particles can elute and release in a short time, calculated by converting the medium liquid volume and the target element equivalent concentration, the medium liquid is the irrigation water of the target plot to fit the actual application scenario, and the composite particles are the biogas slurry and biochar composite particles prepared in the aforementioned embodiment.

[0023] Take a composite particle of the same mass as the one used in the aforementioned short-range elution release equivalence assay and weigh it precisely on an electronic balance with an accuracy of 0.001 g. After weighing, slowly place the composite particle into a 50 mL polytetrafluoroethylene digestion tube, add 10 mL of nitric acid reagent to the digestion tube, and gently shake the digestion tube to ensure full contact between the composite particle and the nitric acid reagent. Let it stand for 30 minutes to allow the composite particle to initially wet. Then, place the digestion tube into a graphite digestion apparatus, start the graphite digestion apparatus and set the temperature program. First, heat at 100°C for 30 minutes, then raise the temperature to 150°C for 60 minutes, and finally raise the temperature to 180°C for 120 minutes, until the composite particle in the digestion tube is completely decomposed and the digestion solution is clear and transparent. After digestion, turn off the heat. Close the graphite digestion apparatus and allow the digestion tube to cool naturally to room temperature. Slowly transfer the clarified digestion solution from the digestion tube to a 50 mL volumetric flask. Rinse the inner wall of the digestion tube several times with deionized water, and pour all the rinsing solution into the volumetric flask to ensure no residue remains. Then, dilute the volumetric flask to the mark with deionized water and gently shake it to mix the digestion solution evenly. Use ultraviolet spectrophotometry to detect the inorganic nitrogen equivalent concentration in the digestion solution after dilution, and use the molybdenum antimony colorimetric method to detect the inorganic phosphorus equivalent concentration in the digestion solution after dilution. Record the concentration values ​​of the two elements separately, add the concentration values ​​of the two elements to obtain the total concentration of the target element, and then multiply the total concentration of the target element by the volumetric flask volume to calculate the total measurable equivalent of the composite particles. Use this total measurable equivalent directly as the total loading equivalent of the composite particles.

[0024] It should be noted that the set mass described in this embodiment is consistent with the set mass of the composite particles used in the aforementioned short-range elution release equivalent acquisition process to ensure the comparability of the detection data. The composite particles are the biogas slurry and biochar composite particles prepared in the aforementioned embodiment. The digestion treatment refers to the complete decomposition of the composite particles using a strong acid reagent, so that all the target elements loaded in the particles are released into the solution. The total measurable equivalent refers to the total content of the target elements in the composite particles that can be measured by detection methods, that is, the sum of the contents of inorganic nitrogen and inorganic phosphorus. The total load equivalent refers to the total amount of target elements loaded in the composite particles, which is equivalent to the total measurable equivalent.

[0025] An acrylic tube with an inner diameter of 2 cm and a height of 10 cm was selected as the particle column preparation device. A layer of qualitative filter paper was laid at the bottom of the acrylic tube to prevent particle leakage and ensure smooth fluid passage. The composite particles prepared in the previous embodiment were evenly poured into the acrylic tube. While pouring, the outer wall of the acrylic tube was gently tapped with a glass rod to ensure uniform filling of the composite particles and avoid gaps or delamination. The filling was completed to a height of 8 cm in the acrylic tube, and then gently compacted with a pressure rod to control the bulk density of the composite particles to 1.2 g / cm³. The particle column with fixed geometric dimensions was then fixed on a permeability analyzer. The temperature of the analyzer was adjusted to a constant temperature of 25°C, and deionized water was introduced as the detection fluid. The fluid pressure was controlled at 0.1 MPa. After the flow rate of the fluid through the particle column stabilized, the fluid flow rate was continuously recorded for 30 minutes. Based on the particle column size, fluid pressure, and stable flow rate, the equivalent conductivity index of the composite particle column was calculated. The granular column was then disassembled, the inner wall of the plexiglass tube was cleaned, and qualitative filter paper of the same specification was laid at the bottom again. Biochar from the same batch as the composite granules, without undergoing biogas slurry compounding treatment, was taken. This biochar, with a particle size of 0.5 to 2 mm, was poured into the plexiglass tube using the same filling method as the composite granules, while simultaneously tapping the tube wall. After filling to a height of 8 cm, it was compacted with the same force using the same pressure bar to ensure the bulk density was consistent with the composite granule column. It was then fixed on a permeability meter, and under the same constant temperature conditions of 25°C and a fluid pressure of 0.1 MPa, the same deionized water was passed through. After the flow rate stabilized, the fluid flow rate was continuously recorded for 30 minutes, and the baseline index of the biochar granule column was calculated. Finally, the ratio of the measured equivalent conductivity index of the composite granule column to the baseline index of the same batch of uncomposite biochar granules was calculated; this ratio is the connectivity ratio of the composite granules.

[0026] It should be noted that the fixed geometric dimensions mentioned in this embodiment are preset uniform specifications to ensure consistent packing density of the granular column. The granular column is a columnar device used to pack composite granules or biochar and perform conductivity detection. The equivalent conductivity index is a parameter characterizing the fluid conductivity within the granular column. The benchmark index is the equivalent conductivity index of the same batch of biochar that has not undergone biogas slurry composite treatment and is packed into granular columns. The connectivity ratio is the ratio of the equivalent conductivity index of the composite granular column to the benchmark index. The same particle size gradation index is consistent with the particle size range of the composite granules. The same batch of biochar refers to biochar from the same batch used to prepare the composite granules and processed by the same pyrolysis and screening process. The composite granules are the biogas slurry and biochar composite granules prepared in the aforementioned embodiment.

[0027] In embodiments of the present invention, the orifice mineralization throat ring index is calculated based on the short-range elution release equivalent, the total load equivalent, and the connectivity ratio, specifically including: Using the connectivity ratio values ​​measured in the aforementioned connectivity ratio measurement examples, the connectivity attenuation factor is calculated according to the formula: In the formula, B represents the connectivity attenuation factor, G represents the equivalent conductivity index of the composite particle column, and G0 represents the benchmark index of the same batch of biochar particles that have not undergone biogas slurry composite treatment. The ratio of the two is the connectivity ratio. The connectivity attenuation factor is calculated by subtracting the connectivity ratio from 1 because the connectivity ratio reflects the connectivity retention ratio of the composite particles relative to the original biochar. Subtracting this ratio from 1 can directly quantify the degree of connectivity attenuation.

[0028] Using the short-range elution release equivalent values ​​measured in the aforementioned short-range elution release equivalent determination example and the total load equivalent values ​​measured in the total load equivalent determination example, the ratio of the short-range elution release equivalent to the total load equivalent is first calculated. Then, this ratio is subtracted from 1. The resulting difference is used to characterize the proportion of target elements in the composite particles that cannot be eluted and released in the short-range elution process relative to the total load. This is because the short-range elution release equivalent reflects the effective load that can be quickly exchanged with the outside environment within the particle pores, while the total load equivalent reflects the total load within the particles. The lower the ratio, the higher the proportion of load that cannot be effectively released within the pores due to pore mineralization precipitation. Subtracting this ratio from 1 can accurately quantify this degree of restriction. Finally, the difference obtained above is multiplied by the connectivity attenuation factor, and the pore mineralization throat band index is calculated according to the formula: In the formula, R represents the orifice mineralization throat ring index. Represents the short-range elution release equivalent. B represents the total load equivalent, and B represents the connectivity attenuation factor. The calculation method of multiplying the two is because the proportion of load that cannot be released in a short distance reflects the impact of pore mineralization on load exchange, and the connectivity attenuation factor reflects the impact of pore mineralization on pore connectivity. The combination of the two can comprehensively and accurately characterize the degree of formation of pore mineralization throat rings. This value indicates that there is a slight pore mineralization throat phenomenon in the composite particles, and the exchange between the load inside the pore and the outside is somewhat restricted but the impact is small.

[0029] It should be noted that the connectivity ratio mentioned in this embodiment is the ratio of the equivalent conductivity index of the composite particle column measured in the previous embodiment to the benchmark index of the same batch of non-composite biochar particle column, which is used to characterize the degree of change in the pore connectivity of the composite particles relative to the original biochar; the connectivity attenuation factor is used to quantify the degree of attenuation of the pore connectivity of the composite particles. The larger the value, the more significant the decrease in pore connectivity caused by mineralization precipitation at the pore opening of the composite particles; the short-range elution release equivalent is the total amount of target elements that can be eluted and released by the composite particles in a short time as measured in the previous embodiment, and the total load equivalent is the total content of target elements in the composite particles as measured in the previous embodiment. The ratio of the two is used to characterize the proportion of target elements that can be exchanged and released in the composite particles to the total load; the pore opening mineralization throat ring zone index is used to characterize the degree of inlet restriction caused by the formation of annular mineralization precipitation zones at the pore opening or throat of the composite particles. The larger the value, the more serious the pore throat valve phenomenon, and the more significant the restriction on the exchange between the load inside the particle pore and the outside.

[0030] In an embodiment of the present invention, the total load equivalent is adjusted based on the orifice mineralization throat ring index to obtain the effective exchange load, specifically including: The correction factor is calculated by calling the orifice mineralization throat ring index value measured in the aforementioned orifice mineralization throat ring index calculation example. The calculation formula is as follows: In the formula, K represents the correction coefficient, and R represents the pore mineralization throat ring index. The reason for calculating the correction coefficient by subtracting the pore mineralization throat ring index from 1 is that the pore mineralization throat ring index characterizes the degree of restriction on the exchange of load within the pore with the outside. Subtracting this index from 1 directly yields the proportion of load within the pore that can be effectively exchanged with the outside, i.e., the correction coefficient. When the pore mineralization throat ring index R is 0.1, substituting it into the formula, we can obtain the correction coefficient K as 1 minus 0.1, resulting in 0.9. This value indicates that 90% of the total load in the composite particles can be effectively exchanged with the outside, while only 10% of the total load cannot effectively participate in the exchange due to the pore mineralization throat phenomenon.

[0031] The total load equivalent value measured in the aforementioned total load equivalent measurement embodiment is used. The total load equivalent is multiplied by the correction factor calculated above, and the effective exchange load is calculated according to the formula: , Q in the formula e ff represents the effective switching load, Q total K represents the total load equivalent, and K represents the correction factor. The calculation method of multiplying the two is because the total load equivalent is the total amount of target elements in the composite particles, and the correction factor is the proportion that can be effectively exchanged. Multiplying the two can accurately calculate the effective load that can actually play a role in the composite particles. This value is the effective exchange load that the composite particles can actually participate in soil nutrient supply and carbon fixation, and can be directly used for subsequent adaptive application rate calculation.

[0032] It should be noted that the pore mineralization throat ring index mentioned in this embodiment is a parameter calculated in the previous embodiment to characterize the degree of inlet restriction caused by mineralization precipitation at the pore mouth of the composite particles. The larger the value, the more severe the pore throat valve phenomenon of the composite particles, and the more significantly the exchange between the load inside the pore and the outside is restricted. The correction coefficient is used to quantify the effective proportion of the total load equivalent of the composite particles that can actually be exchanged with the outside. Its value is negatively correlated with the pore mineralization throat ring index. The total load equivalent is the total content of target elements in the composite particles measured in the previous embodiment. The effective exchange load is the total amount of target elements in the composite particles that can actually participate in soil nutrient supply and carbon fixation. It is the core parameter used for subsequent calculation of adaptive application rate and can accurately reflect the actual effective action capacity of the composite particles.

[0033] In an embodiment of the present invention, the unit area requirement equivalent of the target plot is obtained, the unit area requirement equivalent is divided by the effective exchange load to obtain the unit area application amount, and the composite particles are applied to the target plot according to the unit area application amount, specifically including: Soil sampling and testing were conducted on the target plot. Representative soil samples from different areas of the target plot were selected, and impurities such as stones and weed roots were removed. After natural air drying, crushing, and sieving, the existing content of the target elements in the soil was determined using conventional soil testing methods. Combined with the nutrient requirements of corn during its growth cycle and the soil carbon sequestration target, the required equivalent per unit area of ​​the target plot was determined. Then, the effective exchange load value obtained in the aforementioned effective exchange load calculation example was used. First, the required equivalent per unit area was converted to a unit consistent with the effective exchange load. Then, the required equivalent per unit area was divided by the effective exchange load, and the application rate per unit area was calculated according to the formula: In the formula, A represents the application rate per unit area, D represents the equivalent demand per unit area, and Q... eff The effective exchange load is represented by the calculation method of dividing the two. This is because the unit area demand equivalent is the total amount of target elements required by the target plot, while the effective exchange load is the amount of effective target elements that each unit mass of composite particles can provide. Dividing the two can accurately obtain the amount of composite particles required per unit area to meet the target demand.

[0034] Before application, the prepared composite granules are lightly crushed using a crushing device to ensure no clumping. Then, the composite granules are loaded into the hopper of a fertilizer spreader. The spreader's speed is adjusted to ensure it travels at a uniform speed across the target plot. During spreader operation, the spreader maintains a consistent speed, with parallel and non-overlapping routes to ensure the composite granules are evenly distributed on the soil surface. After spreader operation, a rotary tiller is started, and its tillage depth is adjusted to 18 cm. The tiller travels at a uniform speed across the target plot to till and mix the soil. During tillage, the tiller's teeth are fully engaged in the soil, thoroughly mixing the composite granules on the surface with the soil to a depth of 15-20 cm. After tillage, a harrow is used to lightly level the target plot, ensuring a smooth soil surface and even distribution of the composite granules within the tillage layer. This completes the application and tillage process, ensuring the composite granules effectively perform their carbon sequestration and soil improvement functions.

[0035] It should be noted that the target plot in this embodiment is a large-scale corn-growing farmland. The unit area requirement equivalent is the total amount of target elements that need to be supplemented by composite particles within a unit area of ​​the target plot to meet the nutrient requirements for corn growth and soil carbon sequestration. Its value is determined based on the soil test results of the target plot. The effective exchange load is the total amount of target elements that the composite particles can actually participate in soil nutrient supply and carbon fixation, as calculated in the previous embodiment. The unit area application rate is the mass of composite particles that need to be applied per unit area of ​​the target plot to ensure that the composite particles can meet the requirement equivalent of the target plot. The composite particles are the biogas slurry and biochar composite particles prepared in the previous embodiment. The tillage and mixing operation is used to fully mix the composite particles with the soil to ensure that the composite particles can be evenly distributed in the soil tillage layer and play a role in carbon sequestration and soil improvement.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A system for combined carbon sequestration and soil improvement using biogas slurry and biochar, characterized in that, include: The basic parameter measurement module is used to obtain composite particles prepared from biogas slurry and biochar, and to measure the short-range elution release equivalent, total load equivalent, and connectivity ratio of the composite particles. The core index calculation module is used to calculate the orifice mineralization throat ring index based on short-range elution release equivalent, total load equivalent, and connectivity ratio. The effective load correction module is used to recalculate and correct the total load equivalent based on the orifice mineralization throat ring index to obtain the effective exchange load. An adaptive application decision module is used to obtain the unit area demand equivalent of the target plot, divide the unit area demand equivalent by the effective exchange load to obtain the unit area application amount, and apply the composite particles to the target plot according to the unit area application amount.

2. The system for combined carbon sequestration and soil improvement using biochar and biogas slurry according to claim 1, characterized in that, Obtaining composite particles made from biogas slurry and biochar, including: Biochar is produced by pyrolysis of agricultural waste under anaerobic conditions. Pre-treatment of biogas slurry to remove suspended solids; The biochar and pretreated biogas slurry are mixed at a set mass-volume ratio, and after shaking and settling, they are dried to obtain composite particles.

3. The system for combined carbon sequestration and soil improvement using biochar and biogas slurry according to claim 1, characterized in that, Obtaining the short-range elution release equivalent of the composite particles includes: A set mass of composite particles is added to a set volume of medium liquid. After acting under fixed stirring conditions for a fixed time window, the supernatant is obtained by filtration. The equivalent concentration of the target element in the supernatant is detected and converted according to the set volume of the medium liquid to obtain the short-range elution release equivalent.

4. A system for combined carbon sequestration and soil improvement using biochar and biogas slurry according to claim 3, characterized in that, Obtaining the total loading equivalent of the composite particles includes: Take a composite particle of the same mass as the set mass, and after digestion or extraction, determine the total measurable equivalent of the composite particle. Use the total measurable equivalent as the total load equivalent.

5. A system for combined carbon sequestration and soil improvement using biogas slurry and biochar according to claim 1, characterized in that, Obtaining the connectivity ratio of the composite particles includes: The composite particles are packed into a particle column of fixed geometric size, and the equivalent conductivity or equivalent diffusion index of the particle column is measured. Take biochar of the same particle size distribution as the composite particles and that has not undergone biogas slurry composite treatment, load it and measure the benchmark index; The connectivity ratio is obtained by comparing the equivalent conduction index or equivalent diffusion index with the baseline index.

6. A system for combined carbon sequestration and soil improvement using biogas slurry and biochar according to claim 1, characterized in that, Based on the short-range elution release equivalent, total load equivalent, and connectivity ratio, the orifice mineralization throat ring index is calculated, including: Subtracting the connectivity ratio from 1 yields the connectivity attenuation factor. Calculate the ratio of short-range elution release equivalent to total load equivalent, subtract the ratio from 1, and multiply the difference by the connectivity attenuation factor to obtain the orifice mineralization throat ring index.

7. A system for combined carbon sequestration and soil improvement using biochar and biogas slurry according to claim 1, characterized in that, The total load equivalent is adjusted based on the orifice mineralization throat ring index to obtain the effective exchange load, including: Subtract the orifice mineralization throat ring index from 1 to obtain the correction coefficient; Multiply the total load equivalent by the correction factor to obtain the effective exchange load.

8. A system for combined carbon sequestration and soil improvement using biogas slurry and biochar according to claim 1, characterized in that, The compound granules are applied to the target plot according to the application rate per unit area, including: The compound granules are applied to the surface soil of the target plot at the specified rate per unit area, and the plot is then tilled and mixed to a depth of 15 to 20 centimeters.

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