Preparation method and application of hydrothermal carbon for strengthening soil structure and recarburization and carbon sequestration

Abstract

The invention belongs to the technical field of soil improvement agents, and discloses a preparation method and application of hydrothermal carbon for strengthening a soil structure and recarburization and carbon sequestration, and the method comprises the following steps: step 1, raw material source preparation, step 2, raw material pretreatment, step 3, functional hydrothermal carbon material preparation, step 4, solid-liquid separation, step 5, granulation treatment, and step 6, application. Mushroom residues with high lignin content and high carbon content, straw and trimmed branches are adopted as main raw materials, livestock and poultry manure with high nutrient content and functional groups including iron ore or red mud and bentonite are matched, carbonization treatment is carried out in a high-temperature and high-pressure subcritical hydrothermal environment, and the high-carbon-content high-lignin-content high-carbon-content mushroom residues are obtained. The hydrothermal carbon material with a porous structure and rich oxygen-containing functional groups is prepared. The material can efficiently improve the soil structure, improve the water and fertilizer retention capability of soil, and realize long-term stable recarburization and carbon sequestration effects. The method is low in energy consumption, simple and convenient in preparation process and suitable for medium and low-yield field transformation and high-standard farmland construction.

Description

Technical Field

[0001] The present invention belongs to the field of soil conditioner technology preparation and application, and specifically relates to a preparation method of a functional soil improvement material based on hydrothermal carbon technology and its application in the green and low-carbon transformation of agriculture. Background Art

[0002] Through soil fertility improvement projects, such as improving soil structure, increasing the application of organic fertilizers, promoting soil testing and formula fertilization, and improving farmland water conservancy facilities, we can significantly enhance the water and fertilizer retention capacity and stress resistance of medium- and low-yield farmland, increase yields per unit area, and reduce the risk of agricultural production fluctuations. In recent years, the country has implemented the "storing grain in the land and storing grain in technology" strategy, incorporating the transformation of medium- and low-yield farmland into key tasks for the construction of high-standard farmland. Combining scientific and technological innovation with green production methods, we are promoting the transformation of "barren land into fertile farmland," providing important support for strengthening the foundation of food security and achieving sustainable agricultural development.

[0003] The rational application of organic materials is an important method for improving soil physical and chemical properties, maintaining soil fertility and productivity, and is crucial for enhancing soil aggregate stability and preventing soil erosion. Currently, various crop straws, organic fertilizers, biochar, and humic acid-based materials are widely used for soil fertilization, but these materials have numerous limitations. Specifically, 1) Existing soil improvement materials, such as biochar and organic fertilizers, struggle to simultaneously and efficiently improve soil structure and enhance carbon sequestration. Biochar has a limited effect on soil structure, while organic fertilizers and other materials are not very efficient at enhancing soil carbon. 2) Traditional preparation methods are energy-intensive, time-consuming, and demanding on raw materials, limiting their large-scale application. For example, biochar preparation requires pre-drying of the biomass feedstock, while composting processes generally take a long time, approximately 20-30 days. 3) Currently, the application of functional carbon materials is largely empirical, lacking specific recommendations tailored to soil characteristics and key challenges, resulting in often unsatisfactory organic fertilization efficiency. Summary of the Invention

[0004] The present invention proposes a method for preparing and applying hydrothermal carbon to strengthen soil structure and increase and fix carbon. The method aims to solve the problem that traditional soil improvement materials are difficult to achieve soil structure improvement and carbon increase and fixation simultaneously and efficiently. The carbon-rich material prepared by the method through hydrothermal carbonization technology uses mushroom residues, straw and pruned branches with high lignin and high carbon content as the main raw materials, supplemented by livestock and poultry manure with high nutrient content and functional groups (iron ore or red mud and bentonite), including agricultural and forestry waste and livestock and poultry manure as raw materials, and is produced through dehydration, condensation and other reactions in a high-temperature and high-pressure subcritical hydrothermal environment. Compared with biochar (prepared by high-temperature pyrolysis), hydrothermal carbon is rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface, has stronger hydrophilicity and ion exchange capacity, and the preparation process can directly process high-humidity biomass without the need for pre-drying, with low energy consumption. In soil improvement, the porous structure and surface active groups of hydrochar can effectively promote the formation of soil aggregates, improve soil permeability and water and fertilizer retention; its stable carbon skeleton and rich functional groups can also adsorb heavy metals, passivate pollutants, and improve soil health. In terms of carbon increase and carbon fixation, the aromatic structure of hydrochar gives it high biochemical stability, which can remain in the soil for a long time and reduce the loss of organic carbon mineralization. At the same time, its surface functional groups can fix the unstable carbon in the soil through chemical bonding, further enhancing the carbon fixation effect. In addition, the addition of functional groups (iron oxides and clay minerals) can not only improve the carbon recovery efficiency in the biomass conversion process, but also enhance the efficiency of the material driving soil organic carbon sequestration through direct or indirect effects.

[0005] In order to achieve efficient soil structure improvement and carbon enhancement and sequestration to ensure food security, the present invention provides the following technical solution: a method for preparing hydrothermal charcoal for strengthening soil structure and carbon enhancement and sequestration, the method comprising the following steps:

[0006] Step 1, Source of raw materials

[0007] Carbon-rich biomass with high lignin content, such as mushroom residue, straw and pruned branches, is selected as the main raw materials (including various materials alone or in combination), along with nitrogen- and phosphorus-rich biomass such as livestock and poultry manure, iron-rich minerals such as iron ore or high-iron red mud, and montmorillonite powder;

[0008] Step 2, raw material pretreatment

[0009] Grind high-carbon biomass materials such as collected mushroom residue and pruned branches to a particle size of less than 5mm; use a ball mill to grind montmorillonite powder, iron ore powder / high-iron red mud to less than 100μm. To enhance the loading effect, the bentonite particle size should be within the range of 20-50μm.

[0010] The crushed carbon-rich biomass is mixed with water in a ratio of 1:2.5 to 1:5, and then crushed montmorillonite powder and iron ore (or red mud) are added, with the ratio of montmorillonite powder and iron ore (or red mud) to biomass preferably being 10:1 to 2.5. After stirring evenly, a certain amount of 25% ammonia water and cetyl ammonium bromide are added, with the ratio of ammonia water and cetyl ammonium bromide to biomass solids being 1:0.2 to 0.5:0.01. Stir continuously for 20 minutes to enhance the uniform distribution of montmorillonite powder on the surface of the biomass material; in order to increase the total nutrient content of the target functional hydrochar and enhance its fertilizing effect, livestock and poultry manure rich in nitrogen, phosphorus and potassium is appropriately added during the preparation of the hydrochar, with the addition ratio preferably not exceeding 50%;

[0011] Step 3, preparation process of functional hydrothermal carbon material

[0012] Functional hydrothermal carbon materials are prepared using a direct co-carbonization method. The hydrothermal carbonization reaction temperature is controlled at 180-240°C, the pressure is maintained at 2.5-3.0 MPa, and the reaction time is set at 0.5-2 hours. In order to enhance the iron oxidation activity in the functional material, a slight dilute acid is added to the hydrothermal reaction to reduce the pH of the reaction system to 3.0-3.5.

[0013] Step 4, solid-liquid separation

[0014] After the reaction, the solid product is collected and slightly dried for later use. The liquid product can be reused after filtration and pH adjustment, which can improve the yield of subsequent functional materials while avoiding water pollution caused by the lysis solution.

[0015] Step 5: Granulation

[0016] During granulation, the addition amount of sodium alginate binder is 5%, and the granulation particle size is controlled at 2-4mm to meet the requirements of mechanical application;

[0017] Step 6, Application

[0018] Functional carbon materials can be applied alone or in combination with organic fertilizers according to soil fertility and input costs. For newly reclaimed coarse soil with weak soil fertility and low organic carbon content, functional materials and organic fertilizers can be applied in a mixed manner at an application rate of 600kg-800kg / mu and 800kg / mu respectively. For low-yield fields with average fertility and low organic carbon content, functional materials and organic fertilizers can be applied in combination at an application rate of 400-600kg / mu and 600kg / mu respectively. For medium- and low-yield fields with high fertility and low organic carbon content, functional hydrochar materials can be applied alone at an application rate of 400-600kg / mu. Hydrochar can be applied by broadcasting or hole application 1-2 weeks before crop transplanting.

[0019] Table 1. Application of functional hydrothermal carbon materials of different soil grades

[0020]

[0021] Preferably, in step 1, the natural iron-containing minerals include one or more of hematite Fe2O3, magnetite Fe3O4 and siderite FeCO3.

[0022] Preferably, in step 5, the particle size of the granulated sodium alginate binder is 2-4 mm.

[0023] An application of hydrothermal carbon that strengthens soil structure and increases carbon sequestration. Hydrothermal carbon is used to repair degraded soil, namely compaction and acidification, and shows unique advantages in improving the carbon sequestration capacity of farmland. It can synergistically achieve the multiple goals of "rapid improvement-long-term carbon sequestration-soil fertility improvement" and is an important material for promoting the green and low-carbon transformation of agriculture.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Through the development of materials that can effectively improve soil structure and increase organic carbon content, the active components of hydrochar are used to enhance the formation of soil macroaggregates, driving soil structure improvement; and the inert components of hydrochar are used to achieve a rapid increase in soil organic carbon.

[0026] 2. The active components in hydrothermal charcoal can provide active substances to microorganisms to achieve a rapid increase in microbial activity and abundance, accelerate the circulation of nutrients in the soil, and thus improve soil fertility;

[0027] 3. In view of the low carbonization efficiency of traditional hydrothermal carbon materials, by loading bentonite and iron oxides, the following are achieved: 1) more carbon can be retained in the solid phase during the hydrothermal carbonization of biomass; 2) the stability of the hydrothermal carbon material is improved; 3) the use of iron oxides to fix dissolved organic carbon in the soil, thereby improving the overall carbon fixation efficiency of the material (the role of iron pump);

[0028] 4. Carbon-based materials prepared by hydrothermal carbonization technology use biomass, including agricultural and forestry waste and sludge, as raw materials. They are generated through dehydration and polycondensation reactions in a high-temperature and high-pressure hydrothermal environment, solving the problem of time-consuming and energy-consuming material creation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a flow chart for preparing hydrothermal charcoal for strengthening soil structure and increasing carbon and fixing carbon according to the present invention;

[0030] Figure 2 The effect of functional enhanced hydrochar and other materials on soil organic carbon content and soil aggregate size distribution and stability is shown;

[0031] Figure 3 This is a diagram showing the effects of functionally enhanced hydrochar combined with ordinary organic fertilizer on enhancing soil organic carbon content and soil aggregate formation and stability. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0033] A preparation method and application of hydrothermal carbon for strengthening soil structure and increasing carbon fixation, the method comprising the following steps:

[0034] Step 1, Source of raw materials

[0035] Select carbon-rich biomass such as mushroom residue with high lignin content, fruit tree pruning branches, nitrogen-rich and phosphorus-rich biomass such as livestock and poultry manure, iron ore or high-iron red mud and montmorillonite powder;

[0036] Step 2, raw material pretreatment

[0037] Grind high-carbon biomass materials such as collected mushroom residue and pruned branches to a particle size of less than 5mm; use a ball mill to grind montmorillonite powder, iron ore powder / high-iron red mud to less than 100μm. To enhance the loading effect, the bentonite particle size should be within the range of 20-50μm.

[0038] The crushed carbon-rich biomass is mixed with water in a ratio of 1:2.5 to 1:5, and then crushed montmorillonite powder and iron ore are added. The ratio of the montmorillonite powder and the iron ore to the biomass is preferably 10:1 to 2.5. After stirring evenly, a certain amount of 25% ammonia water and hexadecyl ammonium bromide are added. The ratio of ammonia water and hexadecyl ammonium bromide to biomass solids is 1:0.2 to 0.5:0.01. Stir continuously for 20 minutes to enhance the uniform distribution of montmorillonite powder on the surface of the biomass material. In order to increase the content of total nutrients in the target functional hydrothermal charcoal and enhance its fertilizing effect, nitrogen-rich and phosphorus-rich biomass is appropriately added in the preparation of the hydrothermal charcoal. The addition ratio is preferably not higher than 50%, and the mass ratio is 20%.

[0039] Step 3, preparation of functional hydrothermal carbon materials

[0040] The functional hydrothermal carbon material is prepared by direct co-carbonization method, with the reaction temperature at 180-240°C and 2.5-3.0 MPa for 0.5-2 hours. In order to enhance the iron oxidation activity in the functional material, a slight dilute acid is added during the hydrothermal reaction to reduce the pH of the reaction system to 3.0-3.5.

[0041] Step 4, solid-liquid separation

[0042] After the reaction, the solid product is collected and slightly dried for later use. The liquid product can be reused after filtration and pH adjustment, which can improve the yield of subsequent functional materials while avoiding water pollution caused by the lysis solution.

[0043] Step 5: Granulation

[0044] Add 5% sodium alginate binder or molasses for extrusion granulation to produce functional granular carbon materials suitable for mechanical application;

[0045] Step 6, Application

[0046] Functional carbon materials are applied alone or in combination with organic fertilizers according to the soil fertility conditions.

[0047] A nonlinear function is constructed based on soil background properties (nutrient content, organic carbon content, etc.), material characteristics (material composition, carbon content, stability and nutrient content, etc.) and material prices, and the material application ratio is determined under cost-optimal conditions according to the soil improvement goals.

[0048] [{minP T M stAM≥BM≥0]

[0049] Where (P): price vector (([P_1,P_2,...,P_n]^T))

[0050] (M): Material usage vector (([M_1,M_2,...,M_n]^T))

[0051] (A): Constraint coefficient matrix (including carbon, nutrients, pH and other parameters)

[0052] (B): Demand threshold vector (including target carbon increment, nutrient gap, etc.)

[0053] For newly reclaimed coarse soil with weak soil fertility and low organic carbon content, functional materials and organic fertilizers should be mixed and applied at a rate of 600-800 kg / mu and 800 kg / mu respectively. For low-yield fields with average fertility and low organic carbon content, functional materials and organic fertilizers should be applied in combination at a rate of 400-600 kg / mu and 600 kg / mu respectively. For medium- and low-yield fields with high fertility and low organic carbon content, functional hydrochar materials should be applied alone at a rate of 400-600 kg / mu. Hydrochar should be applied by broadcasting or hole application 1-2 weeks before crop transplanting.

[0054] Table 1. Application of functional hydrothermal carbon materials of different soil grades

[0055]

[0056] In this embodiment, in step 1, the natural iron-containing minerals include one or more of hematite Fe2O3, magnetite Fe3O4 and siderite FeCO3.

[0057] In this embodiment, in step 5, the particle size of the sodium alginate binder granulation is 2-4 mm, so as to cooperate with the integrated ditching and fertilizing machine, thereby reducing the labor cost during application.

[0058] In this embodiment, in step 6, six different treatment methods were used to study the effects on soil properties, including a control group (CK) and six different carbon material addition treatment groups, namely mushroom residue (GZ), biochar (SP), straw hydrochar (SH), pepper hydrochar (HH), pig manure hydrochar (PH), and mushroom residue hydrochar (GH). The average weight diameter of soil aggregates and the soil organic carbon content were determined by wet screening and potassium dichromate external heating methods, respectively. The application method was as follows: the results showed that compared with the blank control group (CK), the effects of the treatment with added iron and bentonite and the treatment with only added carbon material on the average weight diameter of the soil were not much different. All treatments with added hydrochar significantly increased the soil organic carbon content. Among them, the soil organic carbon content of the treatment with loaded bentonite and iron was the highest, 20-30% higher than that of the treatment with added hydrochar alone. The treatment effects of loaded bentonite and iron, loaded iron only, and loaded bentonite only decreased in descending order. This result indicates that the combined addition of iron and bentonite to hydrochar has a more significant effect on increasing soil organic carbon content than single addition.

[0059] In addition, in this embodiment, in step 6, different proportions of functional enhanced hydrochar (weight ratio of 1%, 2%, and 5%) are used in combination with ordinary organic fertilizer, and the carbon fixation efficiency and the effect of strengthening the formation and stabilization of agglomerates of the added materials of the functional hydrochar ratio are gradually enhanced.

[0060] An application of hydrothermal carbon that strengthens soil structure and increases carbon sequestration. Hydrothermal carbon is used to repair degraded soil, namely compaction and acidification, and shows unique advantages in improving the carbon sequestration capacity of farmland. It can synergistically achieve the multiple goals of "rapid improvement-long-term carbon sequestration-soil fertility improvement" and is an important material for promoting the green and low-carbon transformation of agriculture.

[0061] In summary, the carbon-based material prepared by this method through hydrothermal carbonization technology uses biomass, including agricultural and forestry waste and sludge, as raw materials, and is generated through dehydration, polycondensation, and other reactions in a high-temperature, high-pressure hydrothermal environment. Compared with biochar (prepared by high-temperature pyrolysis), hydrothermal carbon is rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups on its surface, possessing stronger hydrophilicity and ion exchange capacity. Furthermore, the preparation process can directly process high-humidity biomass without the need for pre-drying, resulting in lower energy consumption. In soil improvement, the porous structure and surface active groups of hydrothermal carbon can effectively promote the formation of soil aggregates, improve soil permeability and water and fertilizer retention. Its stable carbon skeleton and rich functional groups can also adsorb heavy metals, passivate pollutants, and enhance soil health. In terms of carbon accumulation and sequestration, the aromatic structure of hydrothermal carbon gives it high biochemical stability, allowing it to remain in the soil for a long time, reducing the loss of organic carbon mineralization. At the same time, its surface functional groups can fix unstable carbon in the soil through chemical bonding, further enhancing the carbon sequestration effect.

[0062] Example 1

[0063] Iron (accounting for 0.5%) and bentonite (accounting for 5%) were loaded onto straw, pepper, pig manure and mushroom residue, and reacted at 200°C and 2.8MPa for 1.5 hours. The prepared hydrochar material showed excellent performance in soil improvement. The experimental results showed that after applying the hydrochar material of the present invention, the soil organic carbon content increased by 28% and the soil aggregate stability increased by 35%. Specifically, the treatment effects of loading bentonite and iron, loading only iron, and loading only bentonite decreased in turn. This result shows that the combined addition of iron and bentonite in hydrochar has a more significant effect on increasing the soil organic carbon content than a single addition.

[0064] Example 2

[0065] Biochar prepared from mushroom residue was added to the soil in the same proportion as in Example 1. Through cultivation experiments, it was found that after the application of biochar to the soil, the soil organic carbon content increased by 10%, and the stability of soil aggregates did not increase significantly compared with the blank control group.

[0066] Example 3

[0067] When different proportions of functional hydrochar (weight ratio of 1%, 2%, 5%) are combined with ordinary organic fertilizer, the carbon fixation efficiency and the role of strengthening the formation and stabilization of aggregates are gradually enhanced. The carbon fixation efficiency of hydrochar with a weight ratio of 5% can reach 40%, and it can significantly promote the formation and stabilization of aggregates.

[0068] Compost: Compost is rich in fast-acting nutrients and active organic matter, which can quickly improve soil fertility. However, it is easily decomposed by microorganisms, has a low carbon addition efficiency (only 20-30% of carbon input), and has limited carbon sequestration capacity.

[0069] Hydrothermal charcoal: It has the advantages of both carbon stability of biochar and surface activity of compost. It can not only fix carbon in the long term by stabilizing the carbon pool, but also regulate the physical and chemical properties of the soil in the short term through functional groups. It also has a wider adaptability to raw materials and is particularly suitable for treating high-water content waste.

[0070] Application Potential: Hydrochar demonstrates unique advantages in remediating degraded soils, including addressing soil compaction and acidification, and enhancing carbon sequestration capacity in farmland. These advantages include enhancing water retention in sandy soils, mitigating compaction in heavy clay soils through its porous structure, and buffering pH in acidic soils through its surface functional groups. Compared to the single functions of biochar and compost, hydrochar synergistically achieves the multiple goals of rapid soil improvement, long-term carbon sequestration, and pollution control, making it a crucial material for promoting a green, low-carbon transition in agriculture.

[0071] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0072] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing hydrothermal charcoal for strengthening soil structure and increasing carbon fixation, characterized by: The method comprises the following steps: Step 1, Source of raw materials The main raw materials are carbon-rich biomass with high lignin content from mushroom residues and fruit tree pruning branches, followed by nitrogen, phosphorus and potassium-rich biomass from livestock and poultry manure, iron ore or high-iron red mud and montmorillonite powder; Step 2, raw material pretreatment Grind the collected high-carbon biomass materials, such as mushroom residue, straw, and pruning branches, to a particle size of less than 5mm. Use a ball mill to grind montmorillonite powder, iron ore powder, and high-iron red mud to less than 100μm. To enhance the loading effect, the bentonite particle size should be 20-50μm. The crushed carbon-rich biomass is mixed with water in a ratio of 1:2.5 to 1:5, and then crushed montmorillonite powder and iron ore are added, and the ratio of the montmorillonite powder and the iron ore to the biomass is preferably 10:1 to 2.

5. After stirring evenly, a certain amount of 25% ammonia water and hexadecyl ammonium bromide are added, and the ratio of ammonia water and hexadecyl ammonium bromide to biomass solids is 1:0.2 to 0.5:0.

01. Stir continuously for 20 minutes to enhance the uniform distribution of montmorillonite powder on the surface of the biomass material; in order to increase the total nutrient content of the target functional hydrochar to enhance the soil fertilization effect of the material, nitrogen-rich and phosphorus-rich biomass can be appropriately added in the preparation of the hydrochar, and the addition ratio should not exceed 50% by mass; Step 3, preparation of functional hydrothermal carbon materials The functional hydrothermal carbon material is prepared by direct co-hydrothermal method, with the reaction temperature at 180-240°C and 2.5-3.0 MPa for 0.5-2 hours. In order to enhance the iron oxidation activity in the functional material, a slight dilute acid is added during the hydrothermal reaction to reduce the pH of the reaction system to 3.0-3.

5. Step 4, solid-liquid separation After the reaction, the solid product is collected and slightly dried for later use. The liquid material is filtered and the pH is adjusted before reuse, which improves the yield of subsequent functional materials while avoiding water pollution caused by the lysis solution. Step 5: Granulation Add 5% sodium alginate binder or molasses for extrusion granulation to produce functional granular carbon materials suitable for mechanical application; Step 6, Application Functional carbon materials can be applied alone or in combination with organic fertilizers according to the soil fertility. For newly reclaimed coarse soil with weak soil fertility and low organic carbon content, functional materials and organic fertilizers can be applied in a mixed manner at an application rate of 600kg-800kg / mu and 800kg / mu respectively. For low-yield fields with average fertility and low organic carbon content, functional materials and organic fertilizers can be applied in combination at an application rate of 400-600kg / mu and 600kg / mu respectively. For medium- and low-yield fields with high fertility and low organic carbon content, functional hydrochar materials can be applied alone at an application rate of 400-600kg / mu. Hydrochar can be applied by broadcasting or hole application 1-2 weeks before crop transplanting. Table 1. Application of functional hydrothermal carbon materials of different soil grades 2. The method for preparing hydrothermal charcoal for strengthening soil structure and increasing carbon and fixing carbon according to claim 1, characterized in that: In step 1, the natural iron-containing minerals include one or more of hematite Fe2O3, magnetite Fe3O4 and siderite FeCO3.

3. The method for preparing hydrothermal charcoal for strengthening soil structure and increasing carbon and fixing carbon according to claim 1, characterized in that: In step 5, the particle size of the sodium alginate binder granulation is 2-4 mm.

4. An application of hydrothermal carbon for strengthening soil structure and increasing carbon fixation, based on the preparation method of hydrothermal carbon for strengthening soil structure and increasing carbon fixation according to claims 1-3, characterized in that: Hydrothermal charcoal is applied to newly reclaimed or degraded arable land soils with low organic carbon content and poor structure. It shows unique advantages in improving the carbon sequestration capacity of farmland. It can synergistically achieve the multiple goals of "rapid improvement-long-term carbon sequestration-soil fertility improvement" and is an important material for promoting the green and low-carbon transformation of agriculture.

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