Soil improvement material with microorganisms immobilized by hydrothermal carbon as well as preparation method and application of soil improvement material

Abstract

The invention provides a soil improvement material with microorganisms immobilized by hydrothermal carbon as well as a preparation method and application of the soil improvement material, and relates to the technical field of soil improvement. The soil improvement material with the microorganisms immobilized by the hydrothermal carbon is prepared by mixing the hydrothermal carbon and a microbial liquid, the preparation method comprises the following steps: drying a material for preparing the hydrothermal carbon, crushing the dried material into powder, and carbonizing the material under specific process conditions to obtain the hydrothermal carbon; the hydrothermal carbon is mixed with a microbial liquid, and microorganisms are adsorbed on the hydrothermal carbon under specific conditions, so that the soil improvement material disclosed by the invention is obtained. The target microorganisms are fixed on the hydrothermal carbon by adopting a physical adsorption method, the finally prepared material can improve soil with continuous cropping obstacles, survival and release of the microorganisms entering the soil environment are facilitated, occurrence of plant diseases is slowed down, and growth and development of plants are promoted.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically a soil improvement material with hydrothermal carbon immobilized microorganisms, its preparation method and application. Background Technology

[0002] Currently, due to the long-term, irrational, and proportional application of large-element chemical fertilizers in agriculture, nitrogen, phosphorus, and other macronutrients accumulate in the soil, leading to soil compaction and acidification, a decline in arable land quality, deterioration of soil aggregate structure and texture, and a gradual increase in bulk density. This results in poor soil tilth, reduced agricultural product quality, and decreased productivity. Therefore, soil degradation urgently needs to be addressed. Organic fertilizers are soil-friendly fertilizers and are widely promoted as alternatives to chemical fertilizers. Livestock manure, urban solid waste, crop straw, agricultural by-products, and organic waste from food processing can all be processed into biomass organic fertilizers. Compared with chemical fertilizers, biomass organic fertilizers can significantly improve soil porosity, promote soil nutrient balance, and enhance sustainable soil productivity. Common methods for converting agricultural waste into organic fertilizers include composting and anaerobic fermentation. These methods are simple to operate and can process large quantities of agricultural waste. However, these technologies have disadvantages such as long preparation cycles, large required areas, easy nutrient loss, and secondary pollution. These drawbacks do not meet the current demand for efficient and environmentally friendly utilization of agricultural waste. Therefore, it is necessary to find new methods to convert agricultural waste into organic fertilizer.

[0003] Hydrothermal carbonization (HTC) is a highly efficient and environmentally friendly biomass treatment technology that enables the value-added utilization of solid waste. The HTC process offers significant advantages, including the ability to carbonize wet biomass without drying and the absence of gas emissions due to the dissolution of oxides in the process water. In the HTC process, the feedstock undergoes multiple reactions, including hydrolysis, dehydration, decarboxylation, aromatization, and condensation. Temperature and residence time are the key parameters controlling the HTC process and influencing the structure and properties of the resulting products. Furthermore, under HTC conditions, subcritical water acts as a non-polar solvent, promoting the hydrolysis of biomass organic compounds, leading to rapid depolymerization into water-soluble products. Water, as a solvent, is not only an inexpensive choice and a valuable biomass component but also an environmentally friendly and non-toxic solvent. Additionally, carbonization in an aqueous medium generates oxygen-containing functional groups on the surface of the solid water-carbon. This process produces energy-intensive coal-like water-carbon without gas emissions or feedstock drying. This reduces process costs and energy consumption and increases the versatility of applications, making HTC superior to traditional thermal treatments.

[0004] Bioremediation using microorganisms is a promising and sustainable strategy due to its cost-effectiveness, environmental friendliness, ease of operation, and lack of secondary pollution. However, it also has drawbacks, such as reduced microbial function and survival rates when coexisting with natural microorganisms under environmental stress and conditions. To overcome these limitations, microbial immobilization technology has proven to be an effective and attractive strategy in recent years, as immobilized carrier materials can provide suitable habitats for degrading microorganisms and protect them from adverse environmental conditions. Various materials, such as carrageenan, polyvinyl alcohol, zeolite, sodium alginate, diatomaceous earth, and carbonaceous materials, have been reported as carriers for microbial immobilization. However, some of these still suffer from drawbacks such as poor immobilization efficiency, high cost, low biodegradability, and limited applicability. Compared to other carrier materials, hydrothermal charcoal has attracted widespread attention due to its porosity, which not only improves soil quality but also provides a mild habitat and nutrients for microorganisms. Furthermore, the selective adsorption of nutrients by hydrothermal charcoal facilitates bacterial accumulation on the surface. However, the physicochemical properties of hydrothermal charcoal prepared from different raw materials and at different temperatures vary significantly; therefore, screening suitable carbon materials for microbial adsorption and immobilization is crucial. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms. When the soil amendment material obtained by the preparation method is applied to the soil, it can improve the soil environment, increase the number of soil microorganisms, improve soil quality, reduce the occurrence of plant diseases, and promote plant growth and development.

[0006] Another object of the present invention is to provide a soil amendment material for fixing microorganisms with hydrothermal carbon.

[0007] Another object of the present invention is to provide an application of a soil amendment material for fixing microorganisms with hydrothermal carbon.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms, the method comprising the following steps:

[0010] The dried hydrothermal carbon raw material is crushed into powder, and the powder is mixed with water to carry out hydrothermal carbonization to obtain hydrothermal carbon.

[0011] The hydrothermal charcoal and microbial inoculum are mixed at a mass-volume ratio of 1-2g:50-100mL, so that the microorganisms are adsorbed onto the hydrothermal charcoal to obtain soil amendment material.

[0012] Preferably, the hydrothermal charcoal raw material includes mushroom residue or pepper branches.

[0013] Preferably, the microbial inoculum contains Bacillus subtilis and Trichoderma harzianum.

[0014] More preferably, the volume ratio of the bacterial culture of Bacillus subtilis and Trichoderma harzianum is 2-5:1-2.

[0015] According to the preparation method of claim 1, the mass-to-volume ratio of powder to water during hydrothermal carbonization is 1g:4-10mL.

[0016] Preferably, the temperature of the hydrothermal carbonization is 200-220℃, and the time of the hydrothermal carbonization is 100-150 min.

[0017] Preferably, the adsorption time is 20-24 hours and the adsorption temperature is 25-30°C.

[0018] The present invention also provides a soil amendment material prepared by the preparation method described above.

[0019] The present invention also provides an application of the soil amendment material described above in promoting plant growth and development.

[0020] The present invention also provides an application of the aforementioned soil amendment material in mitigating plant diseases.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention provides a soil amendment material for immobilizing microorganisms using hydrothermal charcoal and its preparation method. The method employs physical adsorption to immobilize microorganisms on the target hydrothermal charcoal, ensuring the survival and release of microorganisms after they enter the soil environment. Furthermore, in the preparation of the hydrothermal charcoal, different materials and carbonization temperatures were selected to obtain hydrothermal charcoal materials with varying C / N ratios, specific surface areas, and pore sizes, thereby screening for the most suitable hydrothermal charcoal material for microbial colonization. Applying this material to the soil to be amended can improve the soil environment, increase the number of soil microorganisms, enhance soil quality, reduce the occurrence of plant diseases, and promote crop growth and development. Attached Figure Description

[0023] Figure 1 The organic matter content and C / N ratio of different hydrothermal carbons;

[0024] Figure 2 The immobilization rates of six types of hydrothermal charcoal for Bacillus subtilis and Trichoderma harzianum are shown in the figure. In the figure, A represents the immobilization rate of hydrothermal charcoal for Bacillus subtilis, and B represents the immobilization rate of hydrothermal charcoal for Trichoderma harzianum.

[0025] Figure 3 The growth and development of chili peppers under different fertilization treatments;

[0026] Figure 4 The aboveground biomass of chili peppers under different fertilization treatments;

[0027] Figure 5 Root dry weight of chili peppers under different fertilization treatments;

[0028] Figure 6 The seedling vigor index of peppers under different fertilization treatments;

[0029] Figure 7 Disease incidence rate of chili peppers under different fertilization treatments;

[0030] Figure 8 The content of catalase (CAT) in pepper roots under different fertilization treatments;

[0031] Figure 9 The content of peroxidase (POD) in pepper roots under different fertilization treatments;

[0032] Figure 10 The content of superoxide dismutase (SOD) in pepper roots under different fertilization treatments;

[0033] Figure 11 The content of malondialdehyde (MDA) in pepper roots under different fertilization treatments. Detailed Implementation

[0034] The present invention also provides a method for preparing the soil amendment material described above, wherein the preparation method preferably includes the following steps:

[0035] The dried hydrothermal carbon raw material is crushed into powder, and the powder is mixed with water to carry out hydrothermal carbonization to obtain hydrothermal carbon.

[0036] The hydrothermal charcoal and microbial inoculum are mixed at a mass-volume ratio of 1-2g:50-100mL, so that the microorganisms are adsorbed onto the hydrothermal charcoal to obtain soil amendment material.

[0037] In this invention, the hydrothermal charcoal raw material includes mushroom residue or Sichuan pepper branches. In this invention, the drying method is preferably to place the hydrothermal charcoal raw material in an oven for drying. The drying temperature is preferably 100-110℃, more preferably 105℃. The drying time is preferably 8-15 hours, more preferably 10-12 hours. In this invention, the mushroom residue or Sichuan pepper branches can be purchased from commercially available products. In this invention, the mushroom residue or Sichuan pepper branches were purchased from Sichuan Chengdu Aokun Agricultural Technology Co., Ltd.

[0038] In this invention, the hydrothermal carbon is sieved and then mixed with microbial liquid. The sieve mesh size is preferably 40-80 mesh, and more preferably 60 mesh.

[0039] In this invention, as a preferred embodiment, the raw materials for preparing hydrothermal char are dried and pulverized into powder. The pulverized powder is then placed in a muffle furnace, with a mass-to-volume ratio of raw material powder to water of 1g:4-10mL, more preferably 1g:5mL. The temperature is then increased to 200-220℃ at a rate of 20℃ / min, and carbonized for 100-150min to obtain carbonized hydrothermal char. In this invention, the hydrothermal carbonization time is more preferably 120min. In this invention, the muffle furnace is preferably an LC-KH-2000 hydrothermal reactor.

[0040] In this invention, the microbial culture contains *Bacillus subtilis* and *Trichoderma harzianum*; the volume ratio of *Bacillus subtilis* to *Trichoderma harzianum* in the culture is 2:1. In an optional embodiment of this invention, the preparation of the *Bacillus subtilis* culture includes the following steps: adding liquid *Bacillus subtilis* inoculum to LB medium and culturing for 22-25 hours at 28-32°C and 160 rpm on a rotary shaker. After culturing, the cells are harvested by centrifugation. The supernatant is discarded, and the lower layer of cells is collected. The cells are washed twice with 0.85% sterile physiological saline to obtain a *Bacillus subtilis* suspension. In an optional embodiment of this invention, the preparation of the *Trichoderma harzianum* culture includes the following steps: adding 2 mL of liquid *Trichoderma harzianum* inoculum to medium containing 50 mL of LPDA and culturing for 22-25 hours at 28-32°C and 160 rpm on a rotary shaker. After culturing, the cells are harvested by centrifugation. The supernatant is discarded, and the lower layer of cells is collected. A *Trichoderma harzianum* suspension was prepared by washing twice with 0.85% sterile physiological saline. In a preferred embodiment of this invention, the prepared *Bacillus subtilis* suspension and *Trichoderma harzianum* suspension were diluted separately, and then the OD values ​​of the *Bacillus subtilis* suspension and *Trichoderma harzianum* suspension were measured separately to ensure the OD values ​​of the two bacterial solutions were equal. 600 After stabilizing at 0.8, the microbial culture solution was obtained by mixing Bacillus subtilis culture solution and Trichoderma harzianum culture solution at a volume ratio of 2:1.

[0041] In this invention, the method for adsorbing microorganisms onto hydrothermal charcoal is preferably carried out under oscillation conditions, wherein the oscillation speed is 220-300 r / min, the adsorption time is preferably 20-24 h, and the adsorption temperature is preferably 25-30 °C. In this invention, the oscillation speed is more preferably 250 r / min, the adsorption time is more preferably 24 h, and the adsorption temperature is more preferably 28 °C.

[0042] This invention enables the production of hydrothermal carbon materials with rich pore size, large specific surface area, and suitable carbon-nitrogen ratio by adjusting the feed-liquid ratio, hydrothermal carbonization time, and temperature. Furthermore, by adjusting the adsorption temperature and adsorption time, the hydrothermal carbon can achieve a high adsorption and fixation rate for microorganisms.

[0043] This invention also provides the application of the soil amendment material described above or the soil amendment material prepared by the described method in promoting plant growth and development. After being applied to the soil, the soil amendment material of this invention can significantly increase plant height, stem diameter, root length, and SPAD value. In this invention, the plant is preferably a chili pepper.

[0044] This invention also provides the application of the soil amendment material described above or the soil amendment material prepared by the described method in mitigating plant diseases. When applied to the soil, the soil amendment material of this invention can significantly reduce the incidence of plant diseases. In this invention, the plant disease is preferably Phytophthora capsici.

[0045] This invention also provides an application of the soil amendment material described above or the soil amendment material prepared by the described method in improving plant stress resistance. After being applied to the soil, the soil amendment material of this invention can increase the activity of antioxidant enzymes in plant roots and reduce MDA content to decrease cell damage, thereby enhancing the plant's stress resistance.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available products.

[0048] Example 1

[0049] A method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms, comprising the following steps:

[0050] The mushroom residue was dried in an oven at 105℃ for 10 hours. Then, the dried mushroom residue was placed in a muffle furnace with a mass-to-volume ratio of mushroom residue to water of 1:5. The carbonization temperature was 220℃, and the temperature inside the muffle furnace was increased at a rate of 20℃ / min. After reaching 220℃, the carbonization time was maintained for 2 hours. The carbonized hydrothermal char was then passed through a 60-mesh sieve to obtain the final hydrothermal char product for later use.

[0051] Two mL of liquid Bacillus subtilis culture was added to 50 mL of LB medium and incubated for 24 h on a shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower bacterial layer was collected. A Bacillus subtilis suspension was prepared by washing twice with 0.85% sterile physiological saline. The Bacillus subtilis suspension was diluted, and its absorbance was measured and stabilized at OD0.05. 600=0.8% to obtain Bacillus subtilis bacterial suspension for later use; 2 mL of liquid Trichoderma harzianum inoculum was added to 50 mL of LDA medium and cultured for 24 h on a rotary shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower layer of cells was collected. Trichoderma harzianum bacterial suspension was prepared by washing twice with 0.85% sterile physiological saline. The Trichoderma harzianum bacterial suspension was diluted, and its absorbance was measured and stabilized at OD. 600 =0.8 to obtain Trichoderma harzianum bacterial solution for later use; mix Bacillus subtilis bacterial solution and Trichoderma harzianum bacterial solution at a volume ratio of 2:1 to obtain microbial solution.

[0052] Take 1g of the final hydrothermal carbon product and mix it with 50mL of microbial inoculum. Under shaking conditions, allow the microorganisms to be adsorbed onto the hydrothermal carbon to obtain soil amendment material. The shaking speed is 250r / min, the adsorption time is 24h, and the adsorption temperature is 28℃.

[0053] Example 2

[0054] Unlike Example 1, the carbonization temperature was 200°C, while the other steps remained the same.

[0055] Example 3

[0056] A method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms, comprising the following steps:

[0057] The pepper branches were dried in an oven at 105℃ for 10 hours. Then, the dried pepper branches were placed in a muffle furnace with a mass-to-volume ratio of pepper branches to water of 1:5. The carbonization temperature was 220℃, and the temperature inside the muffle furnace was increased at a rate of 20℃ / min. After reaching 220℃, the carbonization time was maintained for 2 hours. The carbonized hydrothermal char was then passed through a 60-mesh sieve to obtain the final hydrothermal char product for later use.

[0058] Two mL of liquid Bacillus subtilis culture was added to 50 mL of LB medium and incubated for 24 h on a shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower bacterial layer was collected. A Bacillus subtilis suspension was prepared by washing twice with 0.85% sterile physiological saline. The Bacillus subtilis suspension was diluted, and its absorbance was measured and stabilized at OD0.05. 600=0.8% to obtain Bacillus subtilis bacterial suspension for later use; 2 mL of liquid Trichoderma harzianum inoculum was added to 50 mL of LDA medium and cultured for 24 h on a rotary shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower layer of cells was collected. Trichoderma harzianum bacterial suspension was prepared by washing twice with 0.85% sterile physiological saline. The Trichoderma harzianum bacterial suspension was diluted, and its absorbance was measured and stabilized at OD. 600 =0.8 to obtain Trichoderma harzianum bacterial solution for later use; mix Bacillus subtilis bacterial solution and Trichoderma harzianum bacterial solution at a volume ratio of 2:1 to obtain microbial solution.

[0059] Take 1g of the final hydrothermal carbon product and mix it with 50mL of microbial inoculum. Under shaking conditions, allow the microorganisms to be adsorbed onto the hydrothermal carbon to obtain soil amendment material. The shaking speed is 250r / min, the adsorption time is 24h, and the adsorption temperature is 28℃.

[0060] Example 4

[0061] Unlike Example 3, the carbonization temperature was 200°C, while the other steps remained the same.

[0062] Comparative Example 1

[0063] A method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms, comprising the following steps:

[0064] Pig manure was dried in an oven at 105℃ for 10 hours. After drying, the pig manure was placed in a muffle furnace with a mass-to-volume ratio of 1:5 for pig manure and water. The carbonization temperature was 220℃, and the temperature inside the muffle furnace was increased at a rate of 20℃ / min. After reaching 220℃, the carbonization time was maintained for 2 hours. The carbonized hydrothermal carbon was then passed through a 60-mesh sieve to obtain the final hydrothermal carbon product for later use.

[0065] Two mL of liquid Bacillus subtilis culture was added to 50 mL of LB medium and incubated for 24 h on a shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower bacterial layer was collected. A Bacillus subtilis suspension was prepared by washing twice with 0.85% sterile physiological saline. The Bacillus subtilis suspension was diluted, and its absorbance was measured and stabilized at OD0.05. 600=0.8% to obtain Bacillus subtilis bacterial suspension for later use; 2 mL of liquid Trichoderma harzianum inoculum was added to 50 mL of LDA medium and cultured for 24 h on a rotary shaker at 30 °C and 160 rpm. Cells were harvested by centrifugation at 5000 rpm for 10 min. The supernatant was discarded, and the lower layer of cells was collected. The cells were washed twice with 0.85% sterile physiological saline to obtain a Trichoderma harzianum bacterial suspension. The Trichoderma harzianum bacterial suspension was diluted, and its absorbance was measured and stabilized at OD. 600 =0.8 to obtain Trichoderma harzianum bacterial solution for later use; mix Bacillus subtilis bacterial solution and Trichoderma harzianum bacterial solution at a volume ratio of 2:1 to obtain microbial solution.

[0066] Take 1g of the final hydrothermal carbon product and mix it with 50mL of microbial inoculum. Under shaking conditions, allow the microorganisms to be adsorbed onto the hydrothermal carbon to obtain soil amendment material. The shaking speed is 250r / min, the adsorption time is 24h, and the adsorption temperature is 28℃.

[0067] Comparative Example 2

[0068] Unlike Comparative Example 2, the carbonization temperature was 200℃, while the other steps remained the same.

[0069] Example 7

[0070] The basic properties of the hydrothermal char products prepared in Examples 1-4, Comparative Examples 1 and 2 were tested, and the results are shown in Table 1 and 2. Figure 1 Among them, mushroom residue A is the hydrothermal charcoal product prepared in Example 1, mushroom residue B is the hydrothermal charcoal product prepared in Example 2, Sichuan pepper A is the hydrothermal charcoal product prepared in Example 3, Sichuan pepper B is the hydrothermal charcoal product prepared in Example 4, pig manure A is the hydrothermal charcoal product prepared in Comparative Example 1, and pig manure B is the hydrothermal charcoal product prepared in Comparative Example 2.

[0071] Table 1. Basic properties of different hydrothermal carbons

[0072] deal with <![CDATA[Specific surface area (m 2 / g)]]> Total pore volume (cm3 / g) Average pore size (nm) pH Mushroom residue A 9.09 0.03 14.76 4.95 Mushroom residue B 5.64 0.02 13.78 4.87 Sichuan pepper A 4.60 0.01 7.50 4.63 Sichuan pepper B 5.18 0.01 6.08 4.49 Pig manure A 5.85 0.02 13.99 5.12 Pig manure B 3.58 0.01 9.72 5.48

[0073] According to Table 1 and Figure 1 The C / N ratio, specific surface area, and pore size were used to screen the most suitable hydrothermal charcoal material for microbial colonization from six types of hydrothermal charcoal. Table 1 shows that mushroom residue A likely contains abundant mesopores and micropores, thus having a larger specific surface area. Figure 1 It can be seen that, among the C / N ratios, the C / N ratio of pepper branches is the highest (A:37, B:39), the C / N ratio of pig manure is the lowest (A:14, B:13), and the carbon-nitrogen ratio of mushroom residue is most suitable for the metabolic activities of microorganisms.

[0074] Example 8

[0075] The soil amendment materials prepared in Examples 1-4, Comparative Examples 1 and 2 were centrifuged, and the supernatant was collected. The absorbance was measured at 600 nm using a UV spectrophotometer. The absorbance results showed that the absorbance tended to stabilize after 24 hours of adsorption and fixation. The immobilization rates of Bacillus subtilis and Trichoderma harzianum in the hydrothermal charcoal products obtained in Examples 1-6 were also calculated. Specific results are as follows: Figure 2 .

[0076] The immobilization rate was measured, which showed that the hydrothermal charcoal from mushroom residue had the highest adsorption and immobilization efficiency for both bacteria. The immobilization rate of mushroom residue hydrothermal charcoal for Bacillus subtilis reached about 85%, and the immobilization rate for Trichoderma harzianum reached about 95%.

[0077] Experimental Example 1

[0078] The soil amendment material (mushroom residue hydrothermal carbon-fixed microbial amendment material) prepared in Example 1 was applied to a pot experiment to observe the changes in soil physicochemical properties before and after amendment, as well as its effect on crop growth and development.

[0079] Experimental Methods: This pot experiment consisted of four treatments, each with four replicates: CK: no mushroom residue hydrothermal charcoal or microbial inoculum solution; CM1: only the hydrothermal charcoal product prepared in Example 1; CM2: microbial inoculum solution (Bacillus subtilis inoculum: Trichoderma harzianum inoculum = 2:1), along with ordinary organic fertilizer with the same carbon content as other fertilization treatments; CM3: soil amendment material prepared in Example 1 (mushroom residue hydrothermal charcoal-fixed microbial amendment material). Two pepper plants were planted in each pot. The tested pepper variety was Shuyan Tiaojiao Wang F1. Fertilization in this experiment was as follows: when planting peppers, the materials applied in different treatment groups were mixed evenly with 3 kg of soil as base fertilizer, and then placed in pots for application (microbial inoculum solution irrigation). Twenty days after planting, 3 mL of Phytophthora capsici pathogenic fungus solution (test pathogen: Phytophthora capsici BS-11 strain) was inoculated, and the growth of peppers was observed. The specific fertilization details for each treatment are shown in Table 2 below.

[0080] Experimental location: The potted plant experiment site is located in Baishiyi Agricultural Science Research Institute, the core area of ​​Western (Chongqing) Science City. The local climate is a subtropical humid monsoon climate with an average annual temperature of 17.7℃.

[0081] Basic physical and chemical properties of the soil: pH 7.98, organic matter 11.293 g / Kg, total nitrogen 0.563 g / Kg, available phosphorus 110.55 mg / Kg, available potassium 178.59 mg / Kg.

[0082] Experimental materials: mushroom residue hydrothermal charcoal, Bacillus subtilis, Trichoderma harzianum, common organic fertilizer, urea, superphosphate, potassium sulfate

[0083] Table 2 Fertilization under different treatments

[0084] deal with organic fertilizer N, P, K fertilizer Microbial agents CK - Urea, superphosphate, potassium sulfate - CM1 Mushroom residue hydrothermal charcoal Urea, superphosphate, potassium sulfate - CM2 Ordinary organic fertilizer Urea, superphosphate, potassium sulfate Bacillus subtilis culture medium and Trichoderma harzianum culture medium (2:1) CM3 Mushroom residue hydrothermal charcoal Urea, superphosphate, potassium sulfate Bacillus subtilis culture medium and Trichoderma harzianum culture medium (2:1)

[0085] Experimental results:

[0086] 1. Basic physicochemical properties of soil under different fertilization treatments

[0087] A 50-day pot experiment was conducted to verify the effectiveness of the soil amendment material prepared in this invention. As shown in Table 3, compared with the control group (CK), the contents of organic matter, total nitrogen, available phosphorus, and available potassium in the fertilized soil were significantly increased. Among these, the CM2 treatment showed an increase in soil organic matter content compared to the control group (CK), mainly due to the application of ordinary organic fertilizer with the same carbon content. The CM3 treatment (using mushroom residue hydrothermal charcoal after applying fixed microbial inoculum) showed the highest improvement effect. Compared with the control group (CK), the CM3 treatment increased soil organic matter content by 171.16%, total nitrogen content by 20.27%, available phosphorus content by 44.56%, and available potassium content by 16.07%. Compared with the CM2 treatment, the CM3 treatment increased soil organic matter content by 15.43%, total nitrogen content by 7.23%, available phosphorus content by 40.61%, and available potassium content by 17.69%. Therefore, it can be seen that applying the soil amendment material prepared in Example 1 of the present invention can improve the soil environment, significantly improve soil quality, and at the same time, the effect of improving soil organic matter is better than that of commercially available ordinary organic fertilizer.

[0088] Table 3 Soil physicochemical properties under different fertilization treatments

[0089]

[0090] 2. Effects of different fertilization treatments on the growth and development of chili plants

[0091] like Figure 3 As shown, by measuring the growth of pepper plants and their SPAD values, it was found that compared with the unfertilized (CK) group, the plant growth and SPAD values ​​of all fertilized treatments were higher. Among the fertilized treatments, the plant height, root length, stem diameter, and SPAD value of CM3 (mushroom residue hydrothermal charcoal after application of fixed microbial inoculum) plants were significantly increased.

[0092] like Figures 4-7 As shown, compared with the control group (CK), the aboveground biomass of pepper plants treated with fertilizer ( Figure 4 ), root and stem weight ( Figure 5 ) and seedling strength index ( Figure 6All treatments showed significant improvement. Among the fertilization treatments, the CM3 treatment (mushroom residue hydrothermal charcoal after application of fixed microbial inoculum) showed the most significant improvement. Simultaneously, the incidence of Phytophthora blight in peppers during the crop growing period was statistically analyzed. Compared with the control group (CK), the incidence of Phytophthora blight in the fertilized plants was significantly reduced. Figure 7 Among them, the incidence rate decreased most significantly in the CM3 (mushroom residue hydrothermal charcoal after application of fixed microbial inoculum) treatment.

[0093] 3. Effects of different fertilization treatments on enzyme activity in pepper roots

[0094] like Figures 8-11 As shown, the CAT enzyme activity in the roots of plants under fertilization treatments (CM1, CM2, CM3) was... Figure 8 ), POD enzyme activity ( Figure 9 ) and SOD enzyme activity ( Figure 10 The activity levels of all three enzymes were significantly higher in the CM3 treatment than in the unfertilized treatment (CK), while there was no significant increase in the activity of any of the three enzymes among the fertilization treatments. However, the MDA content in the CM3 treatment showed a significant decreasing trend compared to the control group (CK). Therefore, applying the soil amendment material of this invention can improve antioxidant enzyme activity and reduce MDA content. Figure 11 This reduces cell damage and enhances the activity of antioxidant enzymes, thereby increasing the plant's resistance to stress.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a soil amendment material with hydrothermal carbon immobilized microorganisms, characterized in that, The preparation method includes the following steps: The dried hydrothermal carbon raw material is crushed into powder, and the powder is mixed with water to carry out hydrothermal carbonization to obtain hydrothermal carbon. The hydrothermal charcoal and microbial inoculum are mixed at a mass-volume ratio of 1-2g:50-100mL, so that the microorganisms are adsorbed onto the hydrothermal charcoal to obtain soil amendment material.

2. The preparation method according to claim 1, characterized in that, The raw materials for the hydrothermal charcoal include mushroom residue or pepper branches.

3. The preparation method according to claim 1, characterized in that, The microbial inoculum contains Bacillus subtilis and Trichoderma harzianum.

4. The preparation method according to claim 3, characterized in that, The volume ratio of the bacterial culture of Bacillus subtilis and Trichoderma harzianum is 2-5:1-2.

5. The preparation method according to claim 1, characterized in that, During the hydrothermal carbonization, the mass-to-volume ratio of powder to water is 1g:4-10mL.

6. The preparation method according to claim 1 or 5, characterized in that, The hydrothermal carbonization temperature is 200-220℃, and the hydrothermal carbonization time is 100-150 min.

7. The preparation method according to claim 1, characterized in that, The adsorption time is 20-24 hours, and the adsorption temperature is 25-30℃.

8. Soil amendment material prepared by the preparation method according to any one of claims 1-7.

9. The application of the soil amendment material according to claim 8 in promoting plant growth and development.

10. The application of the soil amendment material according to claim 8 in mitigating plant diseases.

Images