Preparation method of biochar soil conditioner based on agricultural and forestry wastes

Abstract

The invention discloses a preparation method of a biochar soil conditioner based on agricultural and forestry waste, and relates to the technical field of agricultural resource utilization and soil improvement, the method comprises the following steps: S1, selecting suitable raw materials based on physicochemical characteristics of specific agricultural and forestry waste, and performing pretreatment, the method comprises the following steps: S1, pretreating raw materials, S2, carrying out high-temperature pyrolysis on the pretreated raw materials to form biochar, S3, regulating and controlling the mixing ratio of the biochar to an additive based on target soil trace element and organic matter requirements, and S4, carrying out curing and grinding treatment on the mixed material to obtain a conditioner finished product. According to the preparation method of the biochar soil conditioner based on the agricultural and forestry wastes, the soil microbial activity is enhanced, the remediation and long-term stability of a soil ecosystem are promoted, the resource utilization of the wastes is realized, and the biochar soil conditioner has good ecological benefits and sustainability; and the problems of soil nutrient balance and fertility durability can be solved by optimizing and regulating the supplement proportion of trace elements and organic matters.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural resource utilization and soil improvement, and in particular to a method for preparing a biochar soil conditioner based on agricultural and forestry wastes. Background Art

[0002] In modern agricultural and forestry production, soil fertility and nutrient balance directly affect crop yield and quality. However, due to long-term over-exploitation and irrational fertilization, soil in many areas faces serious degradation problems, including reduced organic matter content, imbalance of trace elements, and poor fertility sustainability. These soil problems not only restrict the sustainable development of agriculture, but also have a negative impact on the ecological environment.

[0003] At present, biochar, as an important soil improvement material, has shown significant advantages in improving soil fertility and soil structure. Biochar has a good specific surface area and porous structure, which can effectively adsorb and retain water and nutrients in the soil, while reducing nutrient loss. In addition, biochar is rich in carbon-based organic matter, which can provide a growth environment for soil microorganisms, thereby promoting the recovery of soil ecosystems. However, the traditional biochar preparation technology has the following shortcomings: although biochar can increase the content of certain macroelements (such as nitrogen, phosphorus, and potassium) in the soil, its ability to regulate trace elements such as zinc, iron, and copper is poor, and it cannot meet the comprehensive nutritional needs of plants; traditional preparation methods are difficult to optimize the proportion of organic matter under different soil types and crop requirements, which may lead to unsustainable soil fertility; the existing biochar production process usually adopts high-temperature carbonization, but some organic matter and important plant nutrients may be lost during the process, limiting its soil conditioning effect. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a biochar soil conditioner based on agricultural and forestry wastes, and to optimize and regulate the supplementary ratio of trace elements and organic matter to solve the problems of soil nutrient balance and fertility persistence.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a biochar soil conditioner based on agricultural and forestry wastes, the method comprising: S1. Select appropriate raw materials and pre-treat them based on the physical and chemical properties of specific agricultural and forestry wastes; S2, forming biochar by pyrolyzing the pretreated raw materials at high temperature; S3. Regulate the mixing ratio of biochar and additives based on the target soil trace elements and organic matter requirements, including assigning different weight values ​​according to the soil nutrient requirements and the characteristics of the target soil, and calculating the optimal mixing ratio of biochar and different additives. The specific formula is: ; Among them, F(x) is the comprehensive optimization objective function, which indicates the quality of the final mixing ratio of biochar and additives, wi is the weight of the objective function hi(x), which indicates the importance of a specific soil requirement, hi(x) represents the i-th objective function, x represents the specific mixing ratio of biochar and each additive, and P(x) represents the impact of the mixing ratio on other potential factors; S4. Solidify and grind the mixed material to obtain the finished conditioner, including calculating the compression deformation of the particles under different pressure conditions to ensure close contact between the particles. The specific formula is: ; Among them, G represents the force of interaction between particles during the solidification and grinding process, k represents the elastic property value of the particle material, and y represents the compression deformation between particles; Adjust the curing temperature and grinding pressure parameters according to the compression deformation between particles to ensure that the speed and screen size of the grinding equipment are optimized during transportation and storage of the conditioner to obtain uniform particle distribution.

[0006] Preferably, the S1 comprises: The agricultural and forestry wastes were spectrally scanned to obtain their chemical composition characteristics, calculate the relative intensity of each characteristic peak, and evaluate the carbon content and volatile matter ratio of the raw materials. The specific formula is: ; Among them, B(u) represents the intensity value of the detected light signal, u represents the light frequency shift corresponding to the vibration of the waste molecule, u0 represents the fixed frequency of the incident laser in the spectrometer, and L represents the molecular scattering coefficient; By analyzing the results, the pretreatment process is selected.

[0007] Preferably, S2 includes: Calculate the diffusion rate of raw material molecules in a high temperature environment during pyrolysis and predict the ratio of gasification products and biochar. The specific formula is: ; Wherein, C represents the diffusion rate of the raw material molecules in the gas environment during high-temperature pyrolysis, d represents the thermal motion intensity constant of the molecules, M represents the ambient temperature of the pyrolysis reaction, η represents the resistance value of the pyrolysis gas environment, and p represents the radius of the raw material molecules during the pyrolysis process; Adjust the internal temperature and gas flow rate of the cracking equipment to increase the yield of the target product.

[0008] Preferably, the pretreatment of the agricultural and forestry waste in S1 includes drying the agricultural and forestry waste to reduce its moisture content to 10%-15% and using crushing equipment to process the agricultural and forestry waste to a particle size range of 2mm-5mm.

[0009] Preferably, the temperature range of the high temperature cracking in S2 is 500° C. to 700° C., and the cracking time is 1 hour to 3 hours.

[0010] Preferably, the calculation formula of the influence P(x) of the mixing ratio in S3 on other potential factors is: P(x)=ax 2 +bx+c; Among them, P(x) represents the effect of the mixing ratio on other potential factors, a, b, c represent the unknown coefficients, and x represents the specific mixing ratio of biochar and each additive.

[0011] Preferably, the additives in S3 include potassium fertilizer, magnesium fertilizer, phosphorus fertilizer and humic acid.

[0012] Preferably, the pressure range for solidification of the particles in S4 is 10 MPa to 20 MPa, and the solidification temperature range is 50° C. to 100° C.

[0013] Preferably, the specific surface area of ​​the biochar in S2 is 200m² / g to 500m² / g, and the porosity is 40%-60%.

[0014] Preferably, the wavelength range of the spectral scanning in S1 is 500nm to 800nm.

[0015] It can be seen from the above technical solution that the present invention has the following beneficial effects: The preparation method of the biochar soil conditioner based on agricultural and forestry wastes selects suitable raw materials based on the physical and chemical properties of specific agricultural and forestry wastes and performs pretreatment, forms biochar by high-temperature cracking of the pretreated raw materials, and regulates the mixing ratio of biochar and additives based on the target soil trace elements and organic matter requirements, which not only increases the content of major elements such as nitrogen, phosphorus, and potassium in the soil, but also significantly enhances the regulation ability of trace elements such as zinc, iron, and copper, thereby meeting the comprehensive nutritional needs of plants, reducing the loss of organic matter in the production process, ensuring the efficient retention of carbon-based organic matter in biochar, improving the sustainability of soil fertility, and promoting The restoration and stabilization of the soil ecosystem has achieved the scientific mixing ratio regulation of biochar and additives. Customized production of conditioners can be carried out according to different soil types and crop requirements to meet the needs of diversified agricultural applications. It can effectively absorb and retain water and nutrients in the soil, reduce nutrient loss, improve water and fertilizer utilization efficiency, enhance soil microbial activity, promote the restoration and long-term stability of the soil ecosystem, realize the resource utilization of waste, and reduce pollution to the environment. It has good ecological benefits and sustainability, and optimizes the proportion of trace elements and organic matter supplementation to solve the problems of soil nutrient balance and fertility durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the present invention provides a technical solution: a method for preparing a biochar soil conditioner based on agricultural and forestry wastes, the method comprising: S1. Select appropriate raw materials and pre-treat them based on the physical and chemical properties of specific agricultural and forestry wastes; S2, forming biochar by pyrolyzing the pretreated raw materials at high temperature; S3. Regulate the mixing ratio of biochar and additives based on the target soil trace elements and organic matter requirements, including assigning different weight values ​​according to the soil nutrient requirements and the characteristics of the target soil, and calculating the optimal mixing ratio of biochar and different additives. The specific formula is: ; Among them, F(x) is the comprehensive optimization objective function, which indicates the quality of the final mixing ratio of biochar and additives, wi is the weight of the objective function hi(x), which indicates the importance of a specific soil requirement, hi(x) represents the i-th objective function, x represents the specific mixing ratio of biochar and each additive, and P(x) represents the impact of the mixing ratio on other potential factors; S4. Solidify and grind the mixed material to obtain the finished conditioner, including calculating the compression deformation of the particles under different pressure conditions to ensure close contact between the particles. The specific formula is: ; Among them, G represents the force of interaction between particles during the solidification and grinding process, k represents the elastic property value of the particle material, and y represents the compression deformation between particles; Adjust the curing temperature and grinding pressure parameters according to the compression deformation between particles to ensure that the speed and screen size of the grinding equipment are optimized during transportation and storage of the conditioner to obtain uniform particle distribution.

[0019] In the above embodiment, step S1 analyzes the physical and chemical properties of agricultural and forestry wastes, such as carbon-nitrogen ratio, cellulose content, ash content, etc., selects suitable raw material types and performs pretreatment, such as drying and crushing, to ensure the uniformity and efficiency of the raw materials in the subsequent cracking process. Step S2 adopts high-temperature cracking technology to control the cracking temperature, 300℃-700℃, heating rate and atmosphere, so as to promote the pyrolysis of organic matter to generate biochar with high specific surface area and improve its adsorption capacity. Step S3 is based on the needs of the target soil, and by optimizing the mixing ratio model, the requirements of trace elements, organic matter content and other requirements of various target soils are quantified as weight values, and the optimal mixing ratio is calculated to ensure that biochar and additives meet the needs of improving soil together. Step S4 uses particle compression and grinding technology, combined with the elastic characteristics of the material, to adjust the curing conditions and grinding equipment parameters, to obtain conditioner particles with uniform particle size and appropriate strength, and improve its applicability and storage and transportation stability. Utilizing agricultural and forestry waste resources to prepare biochar can effectively reduce waste accumulation and environmental pollution, while increasing the added value of biochar. By optimizing the mixing ratio of biochar and additives, it can meet the improvement needs of different soils, improve soil fertility and structure, and promote sustainable agricultural development. The particle compression and grinding process can be adjusted to enhance the mechanical strength and storage stability of the product, facilitate long-distance transportation and long-term storage, and flexibly adjust parameters during the preparation process to adapt to different raw material types and target soil requirements, thereby improving the universality of the method.

[0020] S1 includes spectral scanning of agricultural and forestry wastes, obtaining their chemical composition characteristics, calculating the relative intensity of each characteristic peak, and evaluating the carbon content and volatile matter ratio of the raw materials. The specific formula is: ; Among them, B(u) represents the intensity value of the detected light signal, u represents the light frequency shift corresponding to the vibration of the waste molecule, u0 represents the fixed frequency of the incident laser in the spectrometer, and L represents the molecular scattering coefficient; By analyzing the results, the pretreatment process is selected.

[0021] In the above implementation, the molecular vibration characteristics and chemical composition information of agricultural and forestry wastes can be obtained by spectral scanning technology, such as Raman spectroscopy or infrared spectroscopy. Specifically, using the formula Calculate the intensity of the light signal corresponding to the molecular vibration, and infer the main components of the waste (such as the content of cellulose, lignin and hemicellulose) through the intensity of the characteristic peaks and their relative positions. This method helps to evaluate the carbon content and volatile matter ratio of the raw materials, thereby providing data support for the optimization of biochar generation in the subsequent high-temperature pyrolysis process. According to the spectral scanning results, combined with the specific characteristics of the raw materials, select appropriate drying, crushing or other pretreatment processes to ensure the efficiency of the pyrolysis process and product quality. Use spectral technology to quickly and non-destructively analyze the chemical composition of the waste, provide an accurate basis for optimizing the pretreatment process and pyrolysis conditions, and select the best pyrolysis parameters by analyzing the carbon content and volatile matter ratio to produce high-quality biochar. According to the spectral analysis results, select appropriate raw materials and treatment processes to improve the utilization efficiency of waste resources. The spectral scanning method can be applied to different types of agricultural and forestry wastes and has strong versatility.

[0022] S2 includes calculating the diffusion rate of raw material molecules in a high temperature environment during pyrolysis and predicting the ratio of gasification products and biochar. The specific formula is: ; Wherein, C represents the diffusion rate of the raw material molecules in the gas environment during high-temperature pyrolysis, d represents the thermal motion intensity constant of the molecules, M represents the ambient temperature of the pyrolysis reaction, η represents the resistance value of the pyrolysis gas environment, and p represents the radius of the raw material molecules during the pyrolysis process; Adjust the internal temperature and gas flow rate of the cracking equipment to increase the yield of the target product.

[0023] In the above embodiment, by formula Calculating the diffusion rate of raw material molecules in a high-temperature pyrolysis environment can accurately predict the ratio of gasification products and biochar generated by the pyrolysis reaction. The increase in pyrolysis temperature (M) accelerates the thermal motion intensity (d) of the raw material molecules, thereby increasing the generation rate of gasification products, but too high a temperature may lead to a decrease in the carbonization degree of biochar. The viscosity (η) and resistance value of the pyrolysis gas environment will affect the movement and diffusion of the raw material molecules, so it is necessary to optimize the gas flow rate to reduce the resistance. By adjusting the airflow distribution and temperature field distribution in the pyrolysis device, precise control of the target products, such as gasification products and biochar production, can be achieved. This process combines thermochemical reaction kinetics with diffusion behavior analysis to ensure the high efficiency of the pyrolysis process and the controllability of product distribution, thereby meeting the preparation requirements of biochar soil conditioners. By accurately calculating the molecular diffusion rate and optimizing the cracking parameters, it is possible to maximize the production of biochar and reduce energy waste, adjust the airflow and temperature field distribution, reduce the gas environment resistance value, and effectively improve the cracking efficiency. Through calculation and parameter optimization, it can flexibly adapt to different types of agricultural and forestry wastes, improve the universality of the process, and produce biochar with specific properties, such as high specific surface area and carbon content, according to the dynamic adjustment of the molecular diffusion rate to meet the specific needs of soil conditioners.

[0024] The pretreatment of agricultural and forestry wastes in S1 includes drying the agricultural and forestry wastes to reduce their moisture content to 10%-15% and using crushing equipment to process the agricultural and forestry wastes to a particle size range of 2mm-5mm.

[0025] In the above embodiment, the agricultural and forestry waste is dried and crushed to provide an ideal raw material state for the subsequent high-temperature cracking process: Drying: The water content of the waste is reduced to 10%-15% by natural drying, hot air drying or microwave drying. This moisture content range can not only reduce the impact of water evaporation on the cracking efficiency, but also avoid the raw material being too dry and causing uneven pyrolysis reaction. Particle size processing: Use crushing equipment (such as a hammer mill, a ball mill or a slicer) to process the waste to a particle size range of 2mm-5mm. The appropriate particle size helps to increase the specific surface area of ​​the raw material, thereby promoting the uniformity and efficiency of the cracking reaction, while ensuring that the material can be evenly distributed in the cracking equipment to avoid blockage or incomplete reaction. Through the above pretreatment measures, the physical state of the waste can be effectively optimized, providing a good reaction basis for the subsequent cracking process. By reducing the moisture content, the energy consumption in the cracking process is reduced, making the pyrolysis reaction more efficient. Processing to a uniform particle size range improves the fluidity and pyrolysis uniformity of the raw material, and avoids poor cracking effect due to excessive or small particle size. Through appropriate drying treatment, the additional energy consumption caused by water evaporation during pyrolysis can be reduced. This pretreatment method can be applied to various types of agricultural and forestry wastes (such as straw, sawdust, fruit cores, etc.), with strong adaptability and easy operation.

[0026] The temperature range of high temperature pyrolysis in S2 is 500°C to 700°C, and the pyrolysis time is 1 hour to 3 hours. In the above embodiment, by controlling the temperature and time of high temperature pyrolysis, efficient pyrolysis of agricultural and forestry wastes can be achieved, and the yield and quality of biochar can be optimized: Pyrolysis temperature range: When the pyrolysis temperature is in the range of 500°C to 700°C, the organic components in the waste undergo pyrolysis reactions to generate biochar with high carbon content and porous structure, while releasing gasification products such as carbon monoxide, methane and a small amount of liquefied products. The temperature of 500°C to 700°C can balance the biochar yield and carbonization degree. At a lower temperature (500°C), the biochar yield is higher, but the pores are not fully developed; higher temperatures (close to 700°C) increase the specific surface area and adsorption capacity of biochar. Pyrolysis time range: The pyrolysis time is set to 1 hour to 3 hours, which can ensure that the organic components in the raw materials are completely decomposed, while avoiding long-term heating that leads to increased energy consumption or excessive damage to the biochar structure. Short-time (1 hour) pyrolysis is suitable for small-particle and high-reactivity raw materials, while longer time (3 hours) is suitable for large-particle or low-reactivity raw materials to ensure sufficiency and uniformity of pyrolysis. Through the precise control of the above temperature and time, the dynamic process of the pyrolysis reaction can be effectively adjusted to generate high-performance biochar products to meet the specific needs of soil conditioners. By optimizing the pyrolysis temperature and time, biochar with high carbon content, strong stability and well-developed pores can be produced to improve its performance as a soil conditioner. Moderate temperature and time control not only ensures the sufficiency of pyrolysis, but also avoids excessive energy consumption. The pyrolysis parameters can be adjusted according to different types of agricultural and forestry wastes (such as straw, fruit cores, and sawdust), and have strong applicability. The biochar generated by high-temperature pyrolysis has a high specific surface area and adsorption capacity, which can effectively improve the aeration, water retention and nutrient supply capacity of the soil.

[0027] The calculation formula for the effect of the mixing ratio on other potential factors P(x) in S3 is: P(x) = ax 2 +bx+c; Among them, P(x) represents the effect of the mixing ratio on other potential factors, a, b, c represent the unknown coefficients, and x represents the specific mixing ratio of biochar and each additive.

[0028] In the above implementation, a quadratic polynomial model is established to evaluate the effect of the mixing ratio on potential factors (such as soil aeration, water retention or microbial activity): Model parameter analysis: a, b, c are unknown coefficients, which can be determined by experimental data fitting or statistical regression methods; x represents the mixing ratio of biochar and additives, and the ratio can be adjusted within a certain range according to different soil requirements (such as improving water retention or increasing nutrient supply capacity). Calculation process: The quadratic coefficient a is mainly used to characterize the nonlinear effect of the mixing ratio, such as the negative effect on certain properties when the mixing ratio is too high or too low; the linear coefficient b represents the linear effect of the mixing ratio on the performance, which is usually positively correlated with the specific requirements of the soil; the constant term c represents the initial impact value of other potential factors when the mixing ratio remains unchanged. Impact evaluation: By adjusting the value x of the mixing ratio, the effect of P(x) on the performance of different target soils can be dynamically evaluated, thereby achieving the optimal selection of the best ratio. The quadratic polynomial model is used to quantify the effect of the mixing ratio on potential factors, providing clear guidance for mixing optimization. By adjusting the value of parameter x, it can flexibly adapt to different soil property requirements (such as sandy soil, clay soil, etc.). The model is simple in form and easy to calculate, which makes it easy to quickly optimize the mixing ratio in actual production. The model can be extended to other ratio optimization scenarios (such as fertilizers, improvers, etc.) and has strong universality.

[0029] The additives in S3 include potash fertilizer, magnesium fertilizer, phosphate fertilizer and humic acid. In the above embodiment, potash fertilizer, magnesium fertilizer, phosphate fertilizer and humic acid are selected as additives and mixed with biochar to meet the multiple soil improvement needs: Potash fertilizer: Provides the potassium element required for soil plant growth and enhances plant drought resistance and disease resistance; Potash fertilizer combined with biochar can improve nutrient utilization and reduce nutrient loss. Magnesium fertilizer: Supplements magnesium in the soil, improves plant photosynthesis, promotes chlorophyll formation, and synergizes with the pore structure of biochar to help the stability and slow release of magnesium ions in the soil. Phosphorus fertilizer: Increases the effective phosphorus content in the soil and promotes root development; The combination of phosphate fertilizer and biochar helps to reduce phosphorus immobilization and improve phosphorus utilization, which is particularly suitable for poor soils with low phosphorus content. Humic acid: Enhances the organic matter content of the soil and improves the soil structure; After humic acid and biochar are compounded, it can further enhance the water retention and fertilizer retention of the conditioner and support the activity of soil microorganisms. Through the synergistic effect of the above additives and biochar, comprehensive solutions can be provided for different soil improvement needs (such as improving fertility, improving structure, enhancing microbial activity, etc.). The combination of potassium fertilizer, magnesium fertilizer, phosphate fertilizer and humic acid can provide a variety of nutrients required for crop growth. The synergistic effect of additives and biochar effectively reduces nutrient loss and improves the slow-release effect of fertilizers. Through the combination of humic acid and biochar, the physical structure of the soil is improved, the organic matter content is increased, and the soil's ability to retain water and fertilizer is improved. By reducing the excessive use of chemical fertilizers and improving their utilization rate, it helps to reduce agricultural non-point source pollution and is more environmentally friendly. This combination is suitable for a variety of soil conditions such as saline-alkali land, sandy soil and heavy clay, and improves the flexibility and adaptability of agricultural production.

[0030] The pressure range of particle solidification in S4 is 10MPa to 20MPa, and the solidification temperature range is 50℃ to 100℃. In the above embodiment, the particle strength and molding effect of the biochar soil conditioner are ensured by controlling the pressure and temperature of particle solidification. Pressure range (10MPa to 20MPa): Within the pressure range of 10MPa to 20MPa, the mixture of biochar and additives is pressed and molded, which can effectively increase the density and strength of the particles; too low pressure may cause incomplete particle molding or insufficient strength, and too high pressure may cause particle rupture or equipment wear problems; the appropriate pressure level helps the particles to be tightly combined, and improves the mechanical strength and transportation stability of the finished product. Temperature range (50℃ to 100℃): The curing temperature is controlled at 50℃ to 100℃, which can accelerate the evaporation of bound water and free water in the mixture, and promote the chemical reaction between biochar and additives (such as the cross-linking effect of humic acid); below 50℃ may cause the particle curing time to be prolonged or the strength to be insufficient, and above 100℃ may cause thermal decomposition or excessive water loss of the material; the appropriate temperature range can optimize the hardening effect of the particle surface and improve the durability and moisture resistance of the particles. Through the coordinated control of the above pressure and temperature, the particle curing process can ensure the quality stability and applicability of the finished particles. Under appropriate pressure and temperature conditions, the prepared particles have good mechanical strength and compressive resistance, meeting the requirements of storage and transportation; through the coordination of temperature and pressure, the curing process time is significantly shortened and the production efficiency is improved; the particle surface is well hardened, has good moisture resistance and slow release characteristics, and remains stable in the soil environment; the curing process is suitable for various types of agricultural and forestry waste and additive combinations, which can meet the needs of different soil conditions; moderate pressure and temperature control avoids energy waste and equipment loss during high-intensity curing, and reduces the overall production cost.

[0031] The specific surface area of ​​the biochar in S2 is 200m² / g to 500m² / g, and the porosity is 40%-60%. In the above embodiment, by controlling the conditions of the high-temperature pyrolysis process (such as temperature, time and atmosphere), biochar with a specific surface area of ​​200m² / g to 500m² / g and a porosity of 40%-60% is generated to meet the functional requirements of the soil conditioner. Control of specific surface area: The generation of high specific surface area (200m² / g to 500m² / g) biochar depends on the pyrolysis temperature (500℃ to 700℃), heating rate and the organizational structure of the raw material. Higher temperatures help release volatile components and form more microporous structures; within the range of specific surface area, 200m² / g is suitable for soils that require higher fertilizer retention performance, and 500m² / g is suitable for application scenarios that require strong adsorption capacity (such as pollutant adsorption or heavy metal fixation). Control of porosity: The porosity range (40%-60%) is mainly affected by the pyrolysis temperature and raw material characteristics. Optimizing atmosphere conditions (such as inert gas protection or limited oxygen supply) can prevent excessive pore collapse or oxidation; moderate porosity can ensure that biochar has good air permeability and water retention in the soil, while providing a suitable habitat for soil microorganisms. Optimization of thermal cracking conditions: During the cracking process, adjusting the heating rate, pressure, and residence time can further optimize the pore structure and specific surface area of ​​biochar to ensure stable performance. Through the comprehensive control of the above parameters, high-quality biochar that meets the performance requirements of soil conditioners can be produced. Biochar with a high specific surface area has a strong adsorption capacity, which can improve the soil's nutrient retention and heavy metal fixation capacity. Moderate porosity improves the soil's air permeability and water retention, enhances the soil microecological environment, and promotes crop growth. The specific surface area and porosity parameters can be adjusted according to the needs of different soil types (such as sandy soil, clay soil or saline-alkali land) to meet a variety of application scenarios. Through pyrolysis process control, agricultural and forestry waste resources can be fully utilized to prepare high-value-added biochar. Biochar with high specific surface area and porosity can adsorb carbon dioxide in the atmosphere, enhance carbon sequestration capacity, and help achieve the carbon neutrality goal of agricultural production.

[0032] The wavelength range of the spectral scan in S1 is 500nm to 800nm. In the above embodiment, the spectral scanning technology obtains the chemical composition and structural characteristics of agricultural and forestry wastes through light signals in a specific wavelength range (500nm to 800nm), providing a basis for the subsequent optimization of the cracking process. Principle of wavelength range selection: The wavelength range of 500nm to 800nm ​​belongs to the visible light region, which can effectively stimulate molecular vibrations or electronic transitions in agricultural and forestry wastes to generate characteristic spectral signals; this wavelength range covers many absorption peaks and scattering peaks related to the organic components of wastes (such as the characteristic signals of lignin and cellulose), which is suitable for rapid identification of the main components and proportions of wastes. Acquisition of spectral information: By detecting absorption or scattering signals of specific wavelengths, the content distribution of elements such as carbon, hydrogen and oxygen in the waste and their chemical bond structure are analyzed; the physical and chemical properties of the waste (such as carbon-nitrogen ratio, ash content, etc.) are judged by using the changes in characteristic signals within the wavelength range. Data analysis and decision-making: The spectral scanning data is processed (such as baseline correction and normalization) to extract key characteristic peaks; the raw materials are classified and screened in combination with spectral databases or chemometric methods to guide the selection of cracking process parameters (such as temperature and time). Through spectral scanning in the above wavelength range, rapid and accurate analysis of the components of agricultural and forestry waste can be achieved. Through spectral scanning technology, the characteristic signals of key components are captured in the wavelength range of 500nm to 800nm, providing a scientific basis for subsequent process optimization; spectral scanning in this wavelength range does not require complex sample preparation, and the detection is fast and efficient, which is suitable for large-scale raw material screening; the wavelength range covers the characteristic spectra of a variety of agricultural and forestry wastes (such as straw, wood chips, fruit cores, etc.), and the method is highly versatile; by accurately obtaining the physical and chemical properties of the raw materials, the cracking parameters can be adjusted to improve the yield and quality of biochar; the use of scanning equipment in the visible light band has lower equipment costs and operating costs compared to higher energy spectral technologies (such as ultraviolet or infrared spectra).

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a biochar soil conditioner based on agricultural and forestry wastes, characterized in that: The method comprises: S1. Select appropriate raw materials and pre-treat them based on the physical and chemical properties of specific agricultural and forestry wastes; S2, forming biochar by pyrolyzing the pretreated raw materials at high temperature; S3. Regulate the mixing ratio of biochar and additives based on the target soil trace elements and organic matter requirements, including assigning different weight values ​​according to the soil nutrient requirements and the characteristics of the target soil, and calculating the optimal mixing ratio of biochar and different additives. The specific formula is: ； Among them, F(x) is the comprehensive optimization objective function, which indicates the quality of the final mixing ratio of biochar and additives, wi is the weight of the objective function hi(x), which indicates the importance of a specific soil requirement, hi(x) represents the i-th objective function, x represents the specific mixing ratio of biochar and each additive, and P(x) represents the impact of the mixing ratio on other potential factors; S4. Solidify and grind the mixed material to obtain the finished conditioner, including calculating the compression deformation of the particles under different pressure conditions to ensure close contact between the particles. The specific formula is: ； Among them, G represents the force of interaction between particles during the solidification and grinding process, k represents the elastic property value of the particle material, and y represents the compression deformation between particles; Adjust the curing temperature and grinding pressure parameters according to the compression deformation between particles to ensure that the speed and screen size of the grinding equipment are optimized during transportation and storage of the conditioner to obtain uniform particle distribution.

2. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The S1 includes: The agricultural and forestry wastes were spectrally scanned to obtain their chemical composition characteristics, calculate the relative intensity of each characteristic peak, and evaluate the carbon content and volatile matter ratio of the raw materials. The specific formula is: ； Among them, B(u) represents the intensity value of the detected light signal, u represents the light frequency shift corresponding to the vibration of the waste molecule, u0 represents the fixed frequency of the incident laser in the spectrometer, and L represents the molecular scattering coefficient; By analyzing the results, the pretreatment process is selected.

3. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The S2 includes: Calculate the diffusion rate of raw material molecules in a high temperature environment during pyrolysis and predict the ratio of gasification products and biochar. The specific formula is: ; Wherein, C represents the diffusion rate of the raw material molecules in the gas environment during high temperature cracking, d represents the thermal motion intensity constant of the molecules, M represents the ambient temperature of the cracking reaction, η represents the resistance value of the cracking gas environment, and p represents the radius of the raw material molecules during the cracking process; Adjust the internal temperature and gas flow rate of the cracking equipment to increase the yield of the target product.

4. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The pretreatment of agricultural and forestry wastes in S1 includes drying the agricultural and forestry wastes to reduce their moisture content to 10%-15% and using crushing equipment to process the agricultural and forestry wastes into particles with a size range of 2mm-5mm.

5. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The temperature range of the high temperature cracking in S2 is 500° C. to 700° C., and the cracking time is 1 hour to 3 hours.

6. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The calculation formula for the influence of the mixing ratio in S3 on other potential factors P(x) is: P(x) = ax 2 +bx+c; Among them, P(x) represents the effect of the mixing ratio on other potential factors, a, b, c represent the unknown coefficients, and x represents the specific mixing ratio of biochar and each additive.

7. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The additives in S3 include potassium fertilizer, magnesium fertilizer, phosphorus fertilizer and humic acid.

8. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The pressure range of the particles solidification in S4 is 10MPa to 20MPa, and the solidification temperature range is 50°C to 100°C.

9. The method for preparing a biochar soil conditioner based on agricultural and forestry waste according to claim 1, characterized in that: The specific surface area of ​​the biochar in the S2 is 200m² / g to 500m² / g, and the porosity is 40%-60%.

10. The method for preparing a biochar soil conditioner based on agricultural and forestry wastes according to claim 2, characterized in that: The wavelength range of the spectrum scan in S1 is 500nm to 800nm.

Images