Biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration

Abstract

The invention relates to a biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration, and belongs to the technical field of soil pollution remediation. The method comprises the following steps: performing high-temperature pyrolysis on straws or rice hulls at 500-700 DEG C under an anaerobic condition to prepare biochar which is not chemically modified; mixing the biochar with farmland soil according to a mass ratio of 1%-5% to prepare mother soil; the mother soil is applied to a farmland soil plowing layer, and after plowing and irrigation, a soil microenvironment capable of adsorbing and degrading pesticides and regulating and controlling rhizosphere microbial communities at the same time is constructed. Through a microenvironment formed by specific biochar and soil, efficient reduction of pesticide residues and effective blocking of antibiotic resistance gene migration are synergistically achieved, the pesticide residues in the soil are reduced by 60% or above, the total abundance of antibiotic resistance genes in vegetables is reduced by 50% or above, and the safety of agricultural products is remarkably improved while contaminated soil is repaired.

Description

Technical Field

[0001] This invention relates to the field of soil pollution remediation technology, and more specifically, to a biochar soil conditioning method for reducing pesticide residues and blocking the migration of antibiotic resistance genes. Background Technology

[0002] Farmland soil environment is the cornerstone of ensuring food security and sustainable agricultural development. However, the overuse of pesticides such as fungicides has led to increasingly serious soil pesticide pollution problems. Simultaneously, the excessive use of antibiotics in livestock and poultry farming allows them to enter the farmland environment through manure and other means. When antibiotic levels in the environment exceed standards, the native microbial community is severely disturbed and stressed, leading to a significant increase in the abundance of antibiotic-resistant bacteria and the antibiotic resistance genes they carry. More seriously, research has shown that pesticide residues in the soil not only directly pollute crops but also affect the abundance and diversity of antibiotic resistance genes. These resistance genes may enter plants through horizontal gene transfer mediated by soil microorganisms and vegetable endophytes, subsequently threatening human health through the food chain. This combined pollution of pesticides and antibiotic resistance genes increases the difficulty of single-contamination remediation technologies and poses a serious threat to agricultural product safety.

[0003] Currently, remediation technologies for soil pesticide and antibiotic resistance gene pollution mainly include stabilization, chemical leaching, electrokinetic remediation, and bioremediation. Among these, biochar fixation technology is widely used due to its advantages such as wide availability of raw materials, low cost, and environmental friendliness. However, existing studies have indicated that biochar may delay the degradation of certain pesticides through excessive adsorption, and its long-term effects require careful evaluation. The persistent presence of pesticides in soil may exacerbate the risk of resistance gene transfer to crops. Therefore, developing a low-cost, efficient, and risk-free technology that can simultaneously reduce soil pesticides and resistance genes and block their migration to vegetables is of great significance for improving agricultural product safety and ensuring sustainable agricultural development. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a biochar soil conditioning method for reducing pesticide residues and blocking the migration of antibiotic resistance genes. The biochar is prepared by high-temperature pyrolysis and has a rich porous structure and high specific surface area, which can improve the in-situ remediation effect of pesticides in pesticide-contaminated farmland soil, reduce the absorption of pesticides and resistance genes by crops, and promote safe agricultural production and sustainable agriculture.

[0005] This invention provides a biochar soil conditioning method for reducing pesticide residues and blocking the migration of antibiotic resistance genes, comprising: S1: Preparation of unmodified biochar: Straw or rice husk biomass is pyrolyzed at high temperature under anaerobic conditions. After pyrolysis, the resulting product is crushed, ground, sieved, repeatedly washed and filtered, and finally dried to obtain the biochar. S2: Preparation of parent soil: The biochar is mixed with farmland soil at a mass ratio of 1% to 5%, and stirred evenly to obtain biochar parent soil; S3: Soil application: The biochar parent soil is applied to the tillage layer of the farmland to be remediated, and is evenly distributed in the tillage layer by plowing, followed by irrigation to create a soil microenvironment that simultaneously adsorbs and degrades pesticides and regulates the rhizosphere microbial community.

[0006] Furthermore, in step S1, the temperature range of the high-temperature pyrolysis is 500°C to 700°C, and the pyrolysis time is not less than 120 minutes.

[0007] Furthermore, in step S1, the repeated washing and filtration are performed at least three times until the washing solution is neutral.

[0008] Furthermore, in step S1, the sieve mesh size used for sieving is 0.15 mm.

[0009] Furthermore, in step S2, the proportion of biochar added is 2%.

[0010] Furthermore, after step S3, the method further includes: planting and managing crops in the soil microenvironment, including applying base fertilizer, sowing, and performing routine water and fertilizer management. The base fertilizer includes urea, diammonium phosphate, and potassium chloride, with corresponding application rates of 18-22 kg of urea, 5-7 kg of diammonium phosphate, and 12-15 kg of potassium chloride per mu.

[0011] Furthermore, during crop growth, an agricultural fungicide is sprayed onto the soil, the agricultural fungicide including one or both of thiabendazole copper and pyraclostrobin.

[0012] The second aspect of this invention provides the application of biochar in reducing pesticide residues and antibiotic resistance genes in soil and vegetables, in order to achieve the synergistic goal of pesticide residue degradation and antibiotic resistance gene migration blockage.

[0013] The third aspect of the present invention provides a soil microenvironment for simultaneously reducing soil pesticide residues and blocking the migration of antibiotic resistance genes, characterized in that the soil microenvironment is uniformly distributed in the cultivated layer of farmland soil biochar, and the soil microsystem simultaneously reduces the concentration of pesticides in the soil and the abundance of antibiotic resistance genes in vegetables, and repairs the secondary soil pollution and the risk of antibiotic resistance gene migration caused by them.

[0014] This invention addresses the shortcomings of the prior art and has the following beneficial effects: This invention provides a biochar soil conditioning method for reducing pesticide residues and blocking the migration of antibiotic resistance genes. It can significantly promote the degradation of pesticides in the soil, reducing pesticide residues in vegetables by more than 60%, and effectively inhibiting the absorption of antibiotic resistance genes by vegetables. This method utilizes biochar to adsorb and degrade pesticide residues in the soil, effectively controlling pollutant migration, reducing pesticide stress-induced migration and accumulation of antibiotic resistance genes in vegetables mediated by plant endophytes, thereby reducing pesticide residues and the abundance of antibiotic resistance genes in vegetables, and improving the safety of agricultural products while remediating contaminated soil. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the construction of a soil microenvironment that simultaneously adsorbs and degrades pesticides and regulates the rhizosphere microbial community in an embodiment of the present invention.

[0016] Figure 2 This invention illustrates the effect of biochar on the relative abundance of ARGs in Chinese cabbage under the action of thiabendazole copper.

[0017] Figure 3 The residual amount of pyraclostrobin and the BCF value (c) in the soil (a), lettuce roots and leaves (b) in the embodiments of the present invention. Detailed Implementation

[0018] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0020] Example 1: Using straw biochar to reduce thiabendazole copper residues and antibiotic resistance gene (ARG) abundance in Chinese cabbage A method for reducing thiabendazole copper residues and antibiotic resistance gene abundance in Chinese cabbage using straw biochar includes the following steps: Figure 1 As shown: S1: Preparation of biochar: Rice straw was washed with deionized water and air-dried. It was then pulverized using a pulverizer. An appropriate amount of the pulverized rice straw was placed in a box-type high-temperature furnace and heated to 600℃ at a rate of 5℃ / min under a nitrogen atmosphere for pyrolysis for 120 min. After pyrolysis, the mixture was allowed to cool naturally to room temperature. The product was removed and ground in a mortar and pestle, then passed through a 0.15 mm standard sieve. The sieved biochar powder was gently washed with 60℃ deionized water for 10-15 min, followed by vacuum filtration. The washing-filtration process was repeated three times until the washing liquid was neutral. The washed biochar was then dried in a 50℃ oven to constant weight to obtain unmodified straw biochar, which was then sealed and stored for later use.

[0021] S2: Preparation of mother soil: Mix the above-mentioned straw biochar with uncontaminated farmland soil at a mass ratio of 2% to prepare biochar mother soil.

[0022] S3: Soil Application and Microenvironment Construction: The parent soil was thoroughly mixed with the remaining target farmland soil and then applied to the experimental area. Mechanical tillage (to a depth of approximately 20 cm) ensured the biochar parent soil was evenly distributed throughout the topsoil. Irrigation was carried out after tillage to bring the soil moisture content to 70%-80% of field capacity, followed by natural drying. This constructed a soil microenvironment rich in biochar, capable of simultaneously adsorbing and degrading pesticides and regulating the rhizosphere microbial community.

[0023] S4: Crop Planting and Management: After the soil moisture has dried, apply base fertilizer. The base fertilizer components and application rate per mu are: 20 kg urea, 6 kg diammonium phosphate, and 14 kg potassium chloride. Disinfect the cabbage seeds with a 5% hydrogen peroxide solution for 30 min, rinse them thoroughly with deionized water, and then sow them. The experiment was conducted under conventional water and fertilizer management in a greenhouse with a relative humidity of 60-80%, a temperature of 25℃-30℃, and 12 hours of light per day. After 35 days of growth, simulated field application of fungicides was performed by preparing a 500-fold dilution of thiabendazole copper (Longkejun) (1 mL of the solution added to 500 mL of deionized water), and applying 1 mL to the roots of each plant.

[0024] Set up a comparative example: Comparative example 1 does not add biochar, and all other conditions are the same as in example 1. The specific steps are as follows: S1: Disinfect the cabbage seeds with 5% hydrogen peroxide for 30 min, rinse them and sow them directly in soil without added biochar. The greenhouse cultivation conditions are the same as in Example 1. S2: After the cabbage has grown for 35 days, apply 1 mL of 500 times diluted thiabendazole copper solution per plant, using the same method as in Example 1. S3: Harvest cabbage leaves 10 days after application of the pesticide and determine the abundance of antibiotic resistance genes.

[0025] Effect verification: Ten days after application, uniformly grown cabbage leaves and rhizosphere soil samples were collected to determine the abundance of antibiotic resistance genes.

[0026] Pesticide residue detection: Acetonitrile extraction, QuEChERS purification, and high performance liquid chromatography-tandem mass spectrometry were used for determination. The results showed that compared with the control group without added biochar, the treatment group with 2% straw biochar had a 65.2% reduction in thiabendazole copper residue in the soil and a 59.8% reduction in thiabendazole copper residue in cabbage leaves.

[0027] Antibiotic resistance gene (ARG) abundance analysis: The abundance of 16 ARGs was detected using high-throughput quantitative PCR. Results are as follows: Figure 2 As shown, the total abundance of antibiotic resistance genes in cabbage leaves in Comparative Example 1 (drug application only) was 0.0037869, while in Example 1 (biochar + drug application) the total abundance of antibiotic resistance genes was 0.001576719, a decrease of 58.36%. In terms of resistance gene categories, the abundance of aminoglycosides, polypeptides, β-lactams, fosfomycin, kasugamycin, macrolides, multidrugs, polymyxins, sulfonamides, and tetracyclines decreased by 45.55%, 31.98%, 80.89%, 65.26%, 81.32%, 67.47%, 64.92%, 85.27%, 19.94%, and 82.76%, respectively. These results indicate that the soil microenvironment constructed in this invention significantly reduces the accumulation of antibiotic resistance genes in vegetables and effectively blocks the migration of ARGs into the vegetable body.

[0028] Example 2: Using rice husk biochar to reduce pyraclostrobin residues and ARG abundance in soil and lettuce A method for reducing pyraclostrobin residues and antibiotic resistance gene abundance in soil and lettuce using rice husk biochar includes the following steps: S1: Preparation of biochar: Rice husks were used as raw material, and the preparation steps were the same as in Example 1, except that the pyrolysis temperature was set to 500℃, and rice husk biochar was finally obtained. S2: Preparation of simulated contaminated soil and parent soil: Accurately weigh 400g of clean farmland soil, first take 50g of soil and place it in a 2L beaker, add an appropriate amount of pyraclostrobin stock solution and mix well, then add the remaining 350g of soil and mix thoroughly to make the pyraclostrobin concentration reach 5mg / kg; then add the prepared rice husk biochar at a mass ratio of 2%, stir thoroughly and mix evenly to complete the preparation of parent soil and preparation for the remediation of contaminated soil; S3: Soil Microenvironment Construction and Crop Cultivation: Pre-cultured lettuce seedlings were transplanted into the soil mixed with biochar. Slow irrigation was applied after transplanting to ensure full contact between the biochar and the rhizosphere soil, thus constructing and repairing the microenvironment. The seedlings were then cultured for 35 days in an artificial climate chamber at 25°C with a 12h / 12h light / dark cycle.

[0029] Detection method for pyraclostrobin: The method is the same as in Example 1, and the experimental results are as follows. Figure 3 As shown in the figure, P represents pyraclostrobin treatment, BCP represents combined pyraclostrobin and biochar treatment, S represents soil sample, R represents lettuce root sample, L represents lettuce leaf sample, N represents no planting treatment, and * represents the significance level. Compared with the control without biochar, the concentration of pyraclostrobin in the soil and lettuce roots decreased by 63.9%, 66.4%, and 88.8%, respectively, after adding biochar, all of which were statistically significant. However, biochar had no significant effect on the concentration of pyraclostrobin in lettuce leaves. In addition, the addition of biochar significantly reduced the bioaccumulation factor (BCF) of pyraclostrobin in lettuce roots, indicating that biochar can effectively inhibit the absorption of pyraclostrobin by lettuce roots, reduce its bioavailability in the soil, and thus reduce the accumulation of pollutants in vegetables.

[0030] ARGs abundance analysis: A significant decrease in the total abundance of ARGs was also observed, further confirming the universality of the method of this invention for different pesticide-ARGs complex pollution systems.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biochar soil conditioning method for reducing pesticide residues and blocking the migration of antibiotic resistance genes, characterized in that, Includes the following steps: S1: Preparation of unmodified biochar: Straw or rice husk biomass is pyrolyzed at high temperature under anaerobic conditions. After pyrolysis, the resulting product is crushed, ground, sieved, repeatedly washed and filtered, and finally dried to obtain the biochar. S2: Preparation of parent soil: The biochar is mixed with farmland soil at a mass ratio of 1% to 5%, and stirred evenly to obtain biochar parent soil; S3: Soil application: The biochar parent soil is applied to the tillage layer of the farmland to be remediated, and is evenly distributed in the tillage layer by plowing, followed by irrigation to create a soil microenvironment that simultaneously adsorbs and degrades pesticides and regulates the rhizosphere microbial community.

2. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 1, characterized in that, In step S1, the temperature range of the high-temperature pyrolysis is 500°C to 700°C, and the pyrolysis time is not less than 120 minutes.

3. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 1, characterized in that, In step S1, the repeated washing and filtration are performed at least three times until the washing solution is neutral.

4. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 1, characterized in that, In step S1, the sieve used for sieving has a mesh size of 0.15 mm.

5. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 1, characterized in that, In step S2, the biochar addition ratio is 2%.

6. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 1, characterized in that, After step S3, the method further includes: planting and managing crops in the soil microenvironment, including applying base fertilizer, sowing, and performing routine water and fertilizer management. The base fertilizer includes urea, diammonium phosphate, and potassium chloride, with corresponding application rates of 18-22 kg of urea, 5-7 kg of diammonium phosphate, and 12-15 kg of potassium chloride per mu.

7. The biochar soil conditioning method for reducing pesticide residues and blocking antibiotic resistance gene migration according to claim 6, characterized in that, During crop growth, an agricultural fungicide is sprayed onto the soil, the agricultural fungicide including one or both of thiabendazole copper and pyraclostrobin.

8. The application of biochar prepared by any one of claims 1 to 7 in reducing pesticide residues and antibiotic resistance genes in soil and vegetables.

9. A soil microenvironment for simultaneously reducing soil pesticide residues and blocking the migration of antibiotic resistance genes, characterized in that, The soil microenvironment is uniformly distributed in the tillage layer of farmland soil as defined in any one of claims 1-7.

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