A soil remediation agent, a preparation method and application thereof

Abstract

The application provides a soil remediation agent and a preparation method and application thereof, and relates to the technical field of soil remediation. The soil remediation agent comprises 15-20 parts of a microbial agent, 20-25 parts of humic acid, 15-20 parts of fulvic acid, 5-10 parts of soybean meal extract, 1-1.5 parts of seaweed extract and 20-25 parts of plant extract. The microbial agent comprises an inner core composed of straw biochar and a compound bacterial liquid and an outer shell formed by polyethylene glycol monomethyl ether modified chitosan, sodium caseinate and sodium tripolyphosphate. The compound bacterial liquid comprises Bacillus thuringiensis bacterial liquid and Beauveria bassiana bacterial liquid at a volume ratio of 10: (5-8). The soil remediation agent can improve soil structure, relieve acidification and hardening, effectively resist diseases for a long time, fundamentally improve the physicochemical properties and microecological environment of ginger continuous cropping soil and realize comprehensive remediation.

Description

Technical Field

[0001] This application relates to the field of soil remediation technology, and in particular to a soil remediation agent, its preparation method, and its application. Background Technology

[0002] Ginger, belonging to the Zingiberaceae family and the Zingiber genus, is rich in nutrients and possesses high medicinal and economic value, making it an important specialty vegetable in my country. According to research on ginger cultivation, many growers, in pursuit of higher yields and profits, apply excessive amounts of chemical and compound fertilizers. This continuous cropping and large-scale planting of ginger leads to soil compaction, acidification, and damage to soil aggregate structure. It also exacerbates ginger pests and diseases, causing ginger to rot and mold, resulting in a sharp decrease in yield and product quality. Currently, soil-borne diseases are rampant and soil compaction is becoming increasingly serious in ginger-growing areas, severely impacting continuous cropping and ginger quality. This is the main contradiction currently hindering the development of the ginger industry.

[0003] Currently, the main approach to soil improvement in ginger cultivation is to combine bio-organic fertilizer with probiotic preparations. For example, patent CN112723957A discloses a soil remediation microbial agent for preventing continuous cropping obstacles, which includes organic raw materials, silicon-calcium-potassium-magnesium fertilizer, fermentation microbial agent, and compound functional microbial agent. The compound functional microbial agent includes Bacillus subtilis, Bacillus licheniformis, Bacillus polymyxa, and Bacillus amyloliquefaciens. This soil remediation microbial agent can prevent diseases such as root rot and wilt, but it has little effect on soil acidification and soil aggregate structure repair. In addition, the components in this soil remediation microbial agent are simply mixed, and the microbial agent is easily lost, affecting the soil remediation effect and failing to meet the needs of long-term remediation.

[0004] Therefore, there is still a lack of soil remediation agents that can simultaneously prevent and control pests and diseases, repair soil compaction and acidification, and achieve long-term remediation. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of existing technologies by providing a soil remediation agent, its preparation method, and its application. The soil remediation agent provided by this application can improve soil structure, alleviate acidification and compaction, and provide long-term effective disease resistance. It combines the long-term effectiveness of bioremediation with the rapid effectiveness of chemical conditioning, and can fundamentally improve the physical and chemical properties and micro-ecological environment of ginger-continuously cropped soil, thereby achieving comprehensive remediation.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] According to one aspect of this application, a soil remediation agent is provided, comprising, by weight percentage, the following raw materials: 15-20 parts of microbial inoculant, 20-25 parts of humic acid, 15-20 parts of fulvic acid, 5-10 parts of soybean meal extract, 1-1.5 parts of seaweed extract, and 20-25 parts of plant extract; wherein,

[0008] The microbial inoculant consists of a core composed of straw biochar and a compound bacterial solution, and an outer shell formed by polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate; the compound bacterial solution includes Bacillus thuringiensis and Beauveria bassiana in a volume ratio of 10:(5-8);

[0009] The plant extract is selected from at least one of Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract.

[0010] This application uses microbial inoculants as the main agent, combined with humic acid, fulvic acid, etc., to prepare a soil remediation agent. This soil remediation agent can specifically solve problems such as soil acidification, compaction, pests and diseases, and nutrient imbalance in ginger continuous cropping. It takes into account the long-term effect of biological remediation and the rapid effect of chemical conditioning, and can fundamentally improve the physical and chemical properties and micro-ecological environment of ginger continuous cropping soil, so as to achieve comprehensive remediation.

[0011] The above-mentioned soil remediation agent contains microbial inoculants in a mass fraction of 15 to 20 parts, which can be 15, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9, 16, 17, 18, 19, or 20 parts, or any range between them.

[0012] The mass fraction of humic acid is 20 to 25 parts, which can be 20 parts, 20.1 parts, 20.2 parts, 20.3 parts, 20.4 parts, 20.5 parts, 20.6 parts, 20.7 parts, 20.8 parts, 20.9 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts or any range between them;

[0013] The mass fraction of fulvic acid is 15 to 20 parts, which can be 15 parts, 15.1 parts, 15.2 parts, 15.3 parts, 15.4 parts, 15.5 parts, 15.6 parts, 15.7 parts, 15.8 parts, 15.9 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts or any range between them;

[0014] The soybean meal extract is in the range of 5 to 10 parts by weight, for example, 5 parts, 5.1 parts, 5.2 parts, 5.3 parts, 5.4 parts, 5.5 parts, 5.6 parts, 5.7 parts, 5.8 parts, 5.9 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts or any range between them;

[0015] The seaweed extract is present in parts by weight of 1 to 1.5 parts, for example, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts or any range thereof;

[0016] The plant extract is in the range of 20 to 25 parts by weight, which can be 20, 20.1, 20.2, 20.3, 20.4, 20.5, 20.6, 20.7, 20.8, 20.9, 21, 22, 23, 24, 25 parts or any range between them.

[0017] Furthermore, in the aforementioned microbial agent, the mass-to-volume ratio of straw biochar and compound bacterial solution in the core is 1g:(3-5)mL, for example, it can be 1g:3mL, 1g:3.1mL, 1g:3.2mL, 1g:3.3mL, 1g:3.4mL, 1g:3.5mL, 1g:3.6mL, 1g:3.7mL, 1g:3.8mL, 1g:3.9mL, 1g:4mL, 1g:4.5mL, 1g:5mL or any range thereof.

[0018] Furthermore, in the aforementioned microbial agent, the mass ratio of polyethylene glycol monomethyl ether modified chitosan, sodium tyrosine, and sodium tripolyphosphate in the outer shell is 1:(1.5-1.8):(0.3-0.5), for example, it can be 1:1.5:0.3, 1:1.6:0.3, 1:1.7:0.3, 1:1.8:0.3, 1:1.5:0.4, 1:1.5:0.5, 1:1.6:0.4, 1:1.6:0.5, 1:1.7:0.4, 1:1.7:0.5, 1:1.8:0.4, 1:1.8:0.5, or any range thereof.

[0019] Furthermore, in the above-mentioned microbial agent, the mass ratio of the core to the shell is 1:(2 to 2.5), for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5 or any range therebetween.

[0020] Furthermore, among the above-mentioned microbial agents, the effective viable count of Bacillus thuringiensis in the compound bacterial solution is ≥500 million CFU / mL, and the effective viable count of Beauveria bassiana in the compound bacterial solution is ≥500 million CFU / mL.

[0021] Furthermore, the compound bacterial solution also includes any one or a combination of several of Bacillus subtilis, Bacillus licheniformis, Bacillus laterosporus, and actinomycetes, and the effective viable count in the fermentation broth of the above bacteria is ≥100 million CFU / mL.

[0022] Preferably, the compound bacterial solution comprises Bacillus thuringiensis, Beauveria bassiana, Bacillus subtilis, and Actinomycetes in a volume ratio of 10:(5-8):(2-5):(0.5-1).

[0023] This application uses a compound bacterial solution composed of Bacillus thuringiensis and Beauveria bassiana. Bacillus thuringiensis produces insecticidal active substances during its growth and metabolism, exhibiting excellent killing effects against many pests. Beauveria bassiana is an insect pathogen; its spores multiply and secrete toxins upon contact with pests, thus killing them. The synergistic effect of these two bacteria on various pests and diseases enables highly efficient pest and disease control. Further research revealed that when Bacillus subtilis and actinomycetes are added to the compound bacterial solution, Bacillus subtilis can compete with pathogens for nutrients and space, antagonizing the growth of plant pathogens. Furthermore, it can secrete bacteriocins and other antibacterial substances, inhibiting ginger wilt (Ralstonia solanacearum), stem rot, and root rot. Actinomycetes, during their growth and metabolism, secrete chitin, which can destroy the exoskeletons of nematode eggs and larvae, significantly alleviating problems such as ginger root nodules and swollen fibrous roots. Several bacteria, when combined in specific proportions, can work synergistically to achieve the effects of pest and disease control, soil structure improvement, root growth promotion, and soil structure improvement, thereby increasing crop yield and enhancing the safety of long-term continuous cropping.

[0024] Furthermore, the straw biochar includes ginger straw pyrolysis biochar and jute straw pyrolysis biochar with a mass ratio of 1:(2 to 2.5), for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5 or any range between them;

[0025] In the preparation of ginger straw pyrolysis biochar, the temperature is raised to 330-380℃ at a heating rate of 5-10℃ / min, and then kept at this temperature for 2-3 hours. After cooling to room temperature in the furnace, the biochar is crushed, sieved, soaked in 0.1mol / L hydrochloric acid for 1 hour, washed with water until the pH of the filtrate is 5.5-6.5, and finally dried to obtain the product.

[0026] In the preparation of pyrolysis biochar from jute straw, the temperature is raised to 380-430℃ at a heating rate of 5-10℃ / min, and then held at this temperature for 2-3 hours. After cooling to room temperature in the furnace, the biochar is crushed, sieved, soaked in 0.1mol / L citric acid for 1 hour, washed with water until the pH of the filtrate is 5.5-6.5, and finally dried to obtain the final product.

[0027] While the aforementioned compound bacteria can work together to achieve the effects of pest and disease control, soil structure improvement, root growth promotion, and soil structure improvement, directly applying them to ginger planting soil exposes the soil to an acidified environment. Furthermore, the compound bacterial solution does not adsorb into the soil and is easily leached away, resulting in a significant decrease in the number of viable bacteria and thus limiting the soil remediation effect.

[0028] This application uses biochar prepared from ginger straw and jute straw as raw materials as a carrier material for microbial agents. The biochar material has multi-level pores, which can adsorb complex bacteria and has a high loading capacity. The complex bacteria enter the multi-level pores of the biochar, avoiding direct exposure of the complex bacteria to acidified soil, preventing the bacteria from becoming inactive in the early stage of application, and allowing them to adhere to the surface of soil aggregates after application, reducing the loss of the agent, thereby ensuring the number of live bacteria and achieving efficient remediation.

[0029] Furthermore, the polyethylene glycol monomethyl ether modified chitosan in the outer shell is prepared by the following method:

[0030] Chitosan (degree of deacetylation 85-95%, molecular weight 20-50 kDa) was dissolved in 1% acetic acid solution to obtain a chitosan solution. Polyethylene glycol monomethyl ether (molecular weight 2000-5000) was dissolved in anhydrous ethanol and activated at room temperature for 20-30 min. Then, it was slowly added dropwise to the chitosan solution, and the pH was adjusted to 5.0-5.5. The reaction was carried out at room temperature for 12-24 h. After the reaction was completed, anhydrous ethanol was added to precipitate the chitosan, and the mixture was filtered and dried to obtain the final product. The mass ratio of chitosan to polyethylene glycol monomethyl ether was 1:(2-2.8).

[0031] While using biochar-supported microbial agents alone can provide some protection, the rapid release rate of the microorganisms fails to guarantee their long-term activity, resulting in poor long-term remediation effects. To address this, this application utilizes a specific ratio of polyethylene glycol monomethyl ether-modified chitosan, sodium tyrosine, and sodium tripolyphosphate as wall materials to coat the biochar-supported microbial solution. The coated microbial agent maintains uniform swelling and prevents sudden release in ginger soil environments. Its good compatibility with calcium and magnesium fertilizers allows for gradual release of the microorganisms, rather than a one-time release, achieving truly uniform, long-lasting, and controllable slow release for long-term soil remediation. Furthermore, the degradation of this wall material provides nutrients to ginger, promoting root colonization and increasing crop yield.

[0032] Furthermore, the preparation method of the above-mentioned microbial inoculant includes the following steps:

[0033] (1) After sterilizing the straw biochar, mix it with the compound bacterial solution, stir at low speed for 2-3 hours, and dry it until the moisture content is ≤10% to obtain biochar-loaded compound bacteria;

[0034] (2) Place the biochar-loaded composite bacteria in a coating machine, mix polyethylene glycol monomethyl ether modified chitosan, sodium chelate, sodium tripolyphosphate and water to prepare a coating solution with a mass concentration of 2-3%, spray the coating solution by atomization, and dry it until the moisture content is ≤8% to obtain the coating solution.

[0035] Furthermore, the preparation method of the soybean meal extract includes the following steps: adding soybean meal to water, boiling and maintaining for 10-20 minutes, then raising the temperature to 280-300°C and maintaining at this temperature for 10-15 minutes, cooling to room temperature, filtering, and drying the filtrate to obtain the soybean meal extract.

[0036] Further, the preparation method of the seaweed extract includes the following steps: crushing seaweed, adding it to a mixed solution of sodium carbonate and sodium bicarbonate at a material-to-liquid ratio of (10-12):1, heating to 50-60℃ and stirring for 6-8 hours, cooling to room temperature, adjusting the pH to 7.5-8, adding a compound enzyme for enzymatic hydrolysis at a temperature of 30-40℃ for 2-4 hours, separating the solid and liquid, and concentrating under reduced pressure to obtain the seaweed extract;

[0037] In the mixed solution of sodium carbonate and sodium bicarbonate, the content of sodium carbonate is 10-20 g / L and the content of sodium bicarbonate is 5-10 g / L.

[0038] The complex enzyme is an alginate lyase and cellulase in a mass ratio of (2-3):1, and the complex enzyme accounts for 0.1-0.3% of the weight of the seaweed.

[0039] The soil remediation agent of this application contains soybean meal extract and seaweed extract, which work together with microbial agents to further improve soil porosity, promote root growth and seedling development, enlarge ginger rhizomes, increase yield and quality, and reduce yield loss from continuous cropping, without affecting the activity of microbial agents.

[0040] Furthermore, the plant extract is selected from any one or a combination of several of the following: Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract; preferably, the plant extract is selected from Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract in a mass ratio of (25-35):(25-35):(30-50). All of the above plant extracts are commercially available products.

[0041] The aforementioned plant extracts—Curcuma zedoaria extract, Artemisia argyi extract, and garlic extract—when used in a specific ratio, can simultaneously inhibit multiple plant pathogens without significantly inhibiting the microbial agent of this application. By adding these plant extracts, a better synergistic effect can be achieved by simultaneously inhibiting soil-borne pathogens, improving rhizosphere microecology, and inducing disease resistance in ginger, thereby further enhancing the soil remediation effect.

[0042] According to another aspect of this application, a method for preparing a soil remediation agent is provided, comprising the following steps:

[0043] Mix the microbial agent, humic acid, fulvic acid, soybean meal extract, seaweed extract, and plant extract evenly, and dry until the moisture content is ≤10%.

[0044] According to another aspect of this application, the application of the above-mentioned soil remediation agent in preventing and controlling continuous cropping obstacles in ginger is provided.

[0045] Compared with the prior art, this application has the following beneficial effects:

[0046] 1. This application uses microbial inoculants as the main agent, combined with humic acid, fulvic acid, soybean meal extract, seaweed extract, and plant extracts to prepare a soil remediation agent. This soil remediation agent can specifically solve problems such as soil acidification, compaction, pests and diseases, and nutrient imbalance in ginger continuous cropping. It takes into account the long-term effect of bioremediation and the rapid effect of chemical conditioning, and can fundamentally improve the physical and chemical properties and micro-ecological environment of ginger continuous cropping soil, so as to achieve comprehensive remediation.

[0047] 2. This application uses the above-mentioned multi-microbial composite, which is loaded with straw biochar and then coated with polyethylene glycol monomethyl ether modified chitosan, sodium chelate and sodium tripolyphosphate as wall materials. The composite microorganisms work together with the biochar loading and wall material coating to achieve uniform, long-lasting and controllable slow release, realize long-term soil remediation, and provide nutrients for ginger and promote ginger root colonization.

[0048] 3. The addition of plant extracts to the soil remediation agent in this application can simultaneously inhibit soil-borne pathogens, improve rhizosphere microecology, and induce ginger to resist disease, thereby achieving a better synergistic effect and further improving the soil remediation effect. Detailed Implementation

[0049] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described in this patent are for illustrative purposes only.

[0051] The Bacillus thuringiensis, Beauveria bassiana, Bacillus subtilis, Actinomycetes, and Paecilomyces lilacinus used in the following examples are all existing strains available for purchase from the China Microbial Culture Collection Center. This does not involve the development of new strains, but only the application of these existing strains. Furthermore, the Bacillus thuringiensis used in the following examples is selected from strain CICC 10060, Beauveria bassiana is selected from strain CICC 14071 (Beauveria bassiana cocci), Bacillus subtilis is selected from strain CICC24713, Actinomycetes is selected from strain CICC 10650 (common thermophilic actinomycete), and Paecilomyces lilacinus is selected from strain CICC 40276.

[0052] The Bacillus thuringiensis, Beauveria bassiana, Bacillus subtilis, and Actinomycete cultures used in the following examples and comparative examples were prepared by the following methods.

[0053] The preparation method of Bacillus thuringiensis bacterial suspension is as follows:

[0054] The activated seed culture was inoculated into LB liquid medium at an inoculation rate of 3% (v / v) and cultured with shaking at 30°C and 250 rpm for 72 h to obtain Bacillus thuringiensis bacterial suspension with an effective viable count ≥5.0 × 10⁻⁶. 8 CFU / mL.

[0055] The preparation method of Beauveria bassiana inoculum is as follows:

[0056] The activated seed culture was inoculated at a 3% (v / v) inoculation rate into a liquid culture medium consisting of 3.67 g (NH4)2SO4, 0.64 g K2HPO4, 1.04 g MgSO4·7H2O, 0.96 g KCl, 0.02 g FeSO4, 28.3 g sucrose, and 1000 mL distilled water (pH 7.2). The medium was then cultured at 30℃ and 250 rpm with shaking for 72 h to obtain a Beauveria bassiana inoculum culture with an effective viable count ≥ 5.0 × 10⁻⁶ cells / mL. 8 CFU / mL.

[0057] The preparation method of Bacillus subtilis bacterial culture is as follows:

[0058] The activated seed culture was inoculated into the fermentation medium (25 g / L soybean meal, 15 g / L corn starch, 3 g / L yeast extract, 2 g / L dipotassium hydrogen phosphate, 0.8 g / L magnesium sulfate, with the remainder being water, pH 7.2) at a 3% (v / v) inoculation rate. The medium was then cultured at 30℃ with shaking at 220 rpm for 36 h. After 24 h of fermentation, 0.5% (w / v) calcium carbonate was added to adjust the pH to approximately 7.0 to promote spore formation, yielding a Bacillus subtilis fermentation broth with an effective viable count ≥ 5.0 × 10⁻⁶. 8 CFU / mL.

[0059] The preparation method of actinomycete culture is as follows:

[0060] The activated seed culture was inoculated into fermentation medium (5.0–20 g glucose, 1.5–5.0 g peptone, 0.5–5.0 g NaCl, 5.0–20 g millet, 2.0–4.0 g CaCO3, 1000 mL water, pH 7.4) at a 3% (v / v) inoculation rate. The medium was then incubated at 30℃ with shaking at 300 rpm for 36 h. After incubation, the *Bacillus amyloliquefaciens* fermentation broth was obtained, with an effective viable count ≥ 1.0 × 10⁻⁶. 8 CFU / mL.

[0061] The preparation method of Paecilomyces lilacinus liquid is as follows:

[0062] The activated seed culture was inoculated into the fermentation medium (30 g / L corn flour, 10 g / L shrimp meal, 5 g / L sucrose, 0.8 g / L potassium dihydrogen phosphate, 0.4 g / L magnesium sulfate, pH 6.5) at an inoculation rate of 8% (v / v). The medium was then cultured at 25°C and 180 rpm with shaking for 72 hours, with the first 24 hours in the dark followed by 48 hours under light (2000 lux light intensity, 12 hours light / 12 hours dark) to obtain the Paecilomyces lilacinus fermentation broth with an effective viable count ≥ 5.0 × 10⁻⁶. 8 CFU / mL.

[0063] Unless otherwise specified, all chemical reagents used in the embodiments of this application were obtained through conventional commercial channels. Where specific conditions are not specified in the embodiments, they were performed under conventional conditions or conditions recommended by the manufacturer.

[0064] The present application will be further described below by way of specific embodiments.

[0065] Example 1

[0066] This embodiment provides a soil remediation agent, comprising the following raw materials by weight: 15 parts microbial inoculant, 20 parts humic acid, 20 parts fulvic acid, 5 parts soybean meal extract, 1.5 parts seaweed extract, and 25 parts plant extract; wherein,

[0067] The plant extracts include Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract in a mass ratio of 25:25:50;

[0068] The microbial inoculant consists of straw biochar and compound bacterial solution in a mass-to-volume ratio of 1g:3mL, and an outer shell prepared from polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate in a mass ratio of 1:1.5:0.3; the mass ratio of the core to the outer shell is 1:2.

[0069] Straw biochar is prepared by the following method:

[0070] In the preparation of ginger straw pyrolysis biochar, the temperature is increased to 330℃ at a heating rate of 5℃ / min, then held at this temperature for 3 hours, cooled to room temperature with the furnace, pulverized, sieved, soaked in 0.1mol / L hydrochloric acid for 1 hour, washed with water until the pH of the filtrate is 5.5, and finally dried. In the preparation of jute straw pyrolysis biochar, the temperature is increased to 380℃ at a heating rate of 5℃ / min, then held at this temperature for 3 hours, cooled to room temperature with the furnace, pulverized, sieved, soaked in 0.1mol / L citric acid for 1 hour, washed with water until the pH of the filtrate is 5.5, and finally dried. Then, ginger straw pyrolysis biochar and jute straw pyrolysis biochar are mixed at a mass ratio of 1:2.5 to obtain straw biochar.

[0071] The compound bacterial solution is composed of Bacillus thuringiensis bacterial solution and Beauveria bassiana bacterial solution in a volume ratio of 10:5.

[0072] Polyethylene glycol monomethyl ether modified chitosan was prepared by the following method:

[0073] Chitosan (85% deacetylation, 20kDa) was dissolved in a sufficient amount of 1% acetic acid solution to obtain a chitosan solution. Polyethylene glycol monomethyl ether (molecular weight 2000) was dissolved in a sufficient amount of anhydrous ethanol and activated at room temperature for 20 min. Then, it was slowly added dropwise to the chitosan solution (the mass ratio of chitosan to polyethylene glycol monomethyl ether was 1:2). The pH was adjusted to 5.0, and the reaction was carried out at room temperature for 12 h. After the reaction was completed, anhydrous ethanol was added to precipitate the product, which was then filtered and dried to obtain the final product.

[0074] Soybean meal extract was prepared by the following method:

[0075] Add soybean meal to sufficient water, boil and keep for 10 minutes, then heat to 300℃ and keep for 10 minutes, cool to room temperature, filter, and dry the filtrate to obtain soybean meal extract.

[0076] The seaweed extract was prepared by the following method:

[0077] Seaweed was pulverized and added to a mixed solution of sodium carbonate and sodium bicarbonate (sodium carbonate content 10 g / L, sodium bicarbonate content 10 g / L), with a material-to-liquid ratio of 10:1. The mixture was heated to 50℃ and stirred for 6 hours, then cooled to room temperature and the pH was adjusted to 7.5. A compound enzyme was added for enzymatic hydrolysis at 30℃ for 2 hours. Solid-liquid separation was performed, and the mixture was concentrated under reduced pressure to obtain seaweed extract. The compound enzyme consisted of alginate lyase and cellulase in a mass ratio of 2:1, and the amount of the compound enzyme added was 0.1% of the seaweed weight.

[0078] This embodiment also provides a method for preparing a soil remediation agent, including the following steps:

[0079] S1. After sterilizing the straw biochar, mix it with the compound bacterial solution, stir at low speed for 2 hours, and dry it until the moisture content is ≤10% to obtain the biochar-loaded compound bacteria; place the biochar-loaded compound bacteria in a coating machine, mix polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate with water to prepare a coating solution with a mass concentration of 3%, atomize and spray the coating solution, and dry it until the moisture content is ≤8% to obtain the microbial agent;

[0080] S2. Pulverize humic acid, fulvic acid, soybean meal extract, seaweed extract and plant extract separately, mix them evenly, add microbial inoculant and mix well, then dry until the moisture content is ≤10% to obtain the final product.

[0081] Example 2

[0082] This embodiment provides another soil remediation agent, comprising the following components by weight: 20 parts microbial inoculant, 25 parts humic acid, 15 parts fulvic acid, 10 parts soybean meal extract, 1 part seaweed extract, and 20 parts plant extract; wherein,

[0083] The plant extracts include Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract in a mass ratio of 35:35:30.

[0084] The microbial inoculant consists of straw biochar and compound bacterial solution in a mass-to-volume ratio of 1g:3mL, and an outer shell prepared from polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate in a mass ratio of 1:1.8:0.5; the mass ratio of the core to the outer shell is 1:2.5.

[0085] The microbial agent consists of a core and an outer shell covering the core. The core includes straw biochar and compound bacterial solution in a mass-to-volume ratio of 1g:5mL. The outer shell contains polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate in a mass ratio of 1:1.8:0.5. The mass ratio of the core to the outer shell is 1:2.5.

[0086] The above-mentioned straw biochar was prepared by the following method:

[0087] In the preparation of ginger straw pyrolysis biochar, the temperature is increased to 380℃ at a heating rate of 10℃ / min, then held at this temperature for 2 hours, cooled to room temperature with the furnace, pulverized, sieved, soaked in 0.1mol / L hydrochloric acid for 1 hour, washed with water until the pH of the filtrate is 6.5, and finally dried. In the preparation of jute straw pyrolysis biochar, the temperature is increased to 430℃ at a heating rate of 5℃ / min, then held at this temperature for 2 hours, cooled to room temperature with the furnace, pulverized, sieved, soaked in 0.1mol / L citric acid for 1 hour, washed with water until the pH of the filtrate is 6.5, and finally dried. Then, ginger straw pyrolysis biochar and jute straw pyrolysis biochar are mixed at a mass ratio of 1:2 to obtain straw biochar.

[0088] The above-mentioned compound bacterial solution is composed of Bacillus thuringiensis bacterial solution and Beauveria bassiana bacterial solution in a volume ratio of 10:8.

[0089] The above-mentioned polyethylene glycol monomethyl ether modified chitosan was prepared by the following method:

[0090] Chitosan (95% deacetylation, 50kDa) was dissolved in a sufficient amount of 1% acetic acid solution to obtain a chitosan solution. Polyethylene glycol monomethyl ether (5000 molecular weight) was dissolved in a sufficient amount of anhydrous ethanol and activated at room temperature for 30 min. Then, it was slowly added dropwise to the chitosan solution (the mass ratio of chitosan to polyethylene glycol monomethyl ether was 1:2.8). The pH was adjusted to 5.0, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, anhydrous ethanol was added to precipitate the product, which was then filtered and dried to obtain the final product.

[0091] Soybean meal extract was prepared by the following method:

[0092] Add soybean meal to sufficient water, boil and keep for 20 minutes, then heat to 280℃ and keep warm for 15 minutes, cool to room temperature, filter, and dry the filtrate to obtain soybean meal extract.

[0093] The seaweed extract was prepared by the following method:

[0094] The seaweed was crushed and added to a mixed solution of sodium carbonate and sodium bicarbonate (sodium carbonate content 20 g / L and sodium bicarbonate content 5 g / L in the mixed solution) at a material-to-liquid ratio of 12:1. The mixture was heated to 60℃ and stirred for 8 hours, then cooled to room temperature and the pH was adjusted to 8. A compound enzyme was added for enzymatic hydrolysis at 40℃ for 4 hours. The solid and liquid were separated and concentrated under reduced pressure to obtain the seaweed extract.

[0095] The complex enzyme is an alginate lyase and cellulase in a mass ratio of 3:1, and the complex enzyme accounts for 0.3% of the weight of the seaweed.

[0096] This embodiment also provides a method for preparing a soil remediation agent, including the following steps:

[0097] S1. After sterilizing the straw biochar, mix it with the compound bacterial solution, stir at low speed for 3 hours, and dry it until the moisture content is ≤10% to obtain the biochar-loaded compound bacteria; place the biochar-loaded compound bacteria in a coating machine, mix polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate with water to prepare a coating solution with a mass concentration of 3%, atomize and spray the coating solution, and dry it until the moisture content is ≤8% to obtain the microbial agent;

[0098] S2. Mix humic acid, fulvic acid, soybean meal extract, seaweed extract and plant extract evenly, add microbial inoculant and mix well, then dry until the moisture content is ≤10% to obtain the final product.

[0099] Example 3

[0100] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 1 is that the compound bacterial solution also contains Bacillus subtilis and actinomycetes. The volume ratio of Bacillus thuringiensis bacterial solution, Beauveria bassiana bacterial solution, Bacillus subtilis and actinomycetes is 10:5:2:0.5.

[0101] Example 4

[0102] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 1 is that the compound bacterial solution also contains Bacillus subtilis and actinomycetes. The volume ratio of Bacillus thuringiensis bacterial solution, Beauveria bassiana bacterial solution, Bacillus subtilis and actinomycetes is 10:8:5:1.

[0103] Example 5

[0104] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 3 is that the volume ratio of Bacillus thuringiensis bacterial solution, Beauveria bassiana bacterial solution, Bacillus subtilis, and Actinomycetes is 10:8:8:3.

[0105] Example 6

[0106] This embodiment provides another soil remediation agent and its preparation method. The difference from Example 1 is that in the preparation process of polyethylene glycol monomethyl ether modified chitosan, the mass ratio of chitosan to polyethylene glycol monomethyl ether is 1:3.

[0107] Example 7

[0108] This embodiment provides another soil remediation agent and its preparation method. The difference from Example 1 is that in the preparation process of polyethylene glycol monomethyl ether modified chitosan, the mass ratio of chitosan to polyethylene glycol monomethyl ether is 1:1.5.

[0109] Example 8

[0110] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 1 is that the straw biochar is only ginger straw pyrolysis biochar.

[0111] Example 9

[0112] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 1 is that the straw biochar is only jute straw pyrolysis biochar.

[0113] Example 10

[0114] This embodiment provides another soil remediation agent and its preparation method. The difference from Embodiment 1 is that the seaweed extract is prepared by: crushing seaweed, adding it to a mixed solution of sodium carbonate and sodium bicarbonate (the mixed solution contains 20 g / L sodium carbonate and 5 g / L sodium bicarbonate), with a material-to-liquid ratio of 12:1, heating to 60°C and stirring for 8 hours, cooling to room temperature, separating the solid and liquid, and concentrating under reduced pressure to obtain the final product.

[0115] Example 11

[0116] This embodiment provides another soil remediation agent and its preparation method. The difference from Example 1 is that the complex enzyme in the preparation process of the seaweed extract is only cellulase.

[0117] Comparative Example 1

[0118] This comparative example provides another soil remediation agent and its preparation method. The difference from Example 1 is that the compound bacterial solution is composed of Bacillus thuringiensis bacterial solution and Beauveria bassiana bacterial solution in a volume ratio of 1:1.

[0119] Comparative Example 2

[0120] This comparative example provides another soil remediation agent and its preparation method. The difference from Example 1 is that the Beauveria bassiana liquid is replaced with Paecilomyces lilacinus liquid.

[0121] Comparative Example 3

[0122] This comparative example provides another soil remediation agent and its preparation method. The difference from Example 1 is that the microbial agent is prepared by loading the composite bacterial solution with biochar only.

[0123] Comparative Example 4

[0124] This comparative example provides another soil remediation agent and its preparation method. The difference from Example 1 is that the polyethylene glycol monomethyl ether modified chitosan in the outer shell is replaced with unmodified chitosan.

[0125] Comparative Example 5

[0126] This comparative example provides another soil remediation agent and its preparation method, which differs from Example 1 in that the outer shell does not contain sodium tyrosine.

[0127] Comparative Example 6

[0128] This comparative example provides another soil remediation agent and its preparation method, which differs from Example 1 in that the soil remediation agent does not contain seaweed extract.

[0129] Experimental Example 1

[0130] Repair effect test

[0131] A field in Weifang, where ginger has been grown for many years, was selected. The soil bulk density was 1.38-1.40 g / cm³. 3 The total porosity was 47-49%, and the pH was 5.8-6.0. The experiment was conducted in 18 experimental zones, with isolation rows laid during the experiment. Specifically,

[0132] Blank group: Habitual fertilization;

[0133] Experimental group: conventional fertilization + 100 kg / mu of soil remediation agent (soil remediation agent obtained from the above examples and comparative examples).

[0134] The usual fertilization schedule is as follows: apply base fertilizer on April 10th at a rate of 270 kg / mu; from May 10th to June 15th, apply 2 kg of high-nitrogen water-soluble fertilizer every 7 days, for a total of about 5 applications; from June 15th to July 10th, perform two small hilling operations, each time applying 100 kg / mu of soybean meal organic fertilizer and 30 kg / mu of high-nitrogen and high-potassium compound fertilizer; on August 5th, perform large hilling operations, applying 100 kg / mu of soybean meal organic fertilizer and 25 kg / mu of high-potassium compound fertilizer; from August 25th to October 20th, apply 4 kg / mu of high-nitrogen and high-potassium water-soluble fertilizer every 5 days, for a total of about 12 applications.

[0135] The experimental results are shown in Table 1 below.

[0136] Table 1. Repair Results

[0137]

[0138] The results showed that the soil remediation agents prepared in Examples 1 and 2 of this application could effectively reduce soil bulk density, improve the pH of acidic soil, increase soil porosity, reduce the occurrence of ginger blight, and increase ginger yield.

[0139] Compared to Example 1, Examples 3 and 4 use a combination of four bacteria, which helps to increase ginger yield.

[0140] In Examples 6 and 7, the proportion of polyethylene glycol monomethyl ether modified chitosan was changed. In Comparative Example 4, unmodified chitosan was used as the outer shell. In Comparative Example 5, sodium tyrosine was not added to the outer shell. In Comparative Example 3, the composite bacterial solution was loaded with biochar without outer shell coating, resulting in a decrease in the soil remediation effect, the improvement of ginger wilt, and the decrease in ginger yield. This may be because the outer shell material in the microbial agent was changed, which could not form a good protective and slow-release effect on the composite bacterial agent, thus failing to exert its remediation effect.

[0141] In Examples 8 and 9, only one type of straw biochar was used, which increased the incidence of ginger fever and reduced crop yield. This is because the combination of two types of biochar is more conducive to protecting the inoculant and achieving efficient remediation.

[0142] In Comparative Example 1, the change in the ratio of Bacillus thuringiensis and Beauveria bassiana inoculum significantly reduced the soil remediation effect. This indicates that the Bacillus thuringiensis and Beauveria bassiana inoculum work together to achieve synergistic effects in pest and disease control, soil nutrient activation, straw degradation, root growth promotion, and soil structure improvement.

[0143] Experiment Example 2

[0144] Performance testing of soil remediation agents

[0145] Stability: The soil remediation agents prepared in the above examples and comparative examples were sealed and stored in a cool, dry place at 25°C for 12 months. The viable count of each strain was measured, and the viable count retention rate was calculated according to the following formula:

[0146] Viable cell retention rate = (Viable cell count after 12 months / Initial viable cell count) × 100%;

[0147] Strain activity retention rate: The soil remediation agents of Examples 1-11 and Comparative Examples 1-4 of this application were applied to acidic soil with a pH of 5.8 at a dosage of 20 g / kg of soil. The test crop was ginger. Seven days after soil application, the viable counts of several bacteria in the soil were measured, and the activity retention rate was calculated according to the following formula:

[0148] Activity retention rate = (number of viable bacteria 7 days after application / initial number of viable bacteria) × 100%.

[0149] The test results are shown in Table 2.

[0150] Table 2. Stability Test Results

[0151]

[0152] The results showed that the soil remediation agent provided in this application could retain about 80% of the bacterial strain activity in acidic soil, which may be because the acidic environment has a certain inhibitory effect on the compound bacteria; after 12 months of sealed storage, the viable bacteria retention rate was more than 70%, which showed good stability.

[0153] Compared to Example 1, the proportion of polyethylene glycol monomethyl ether modified chitosan in Examples 6 and 7 was changed. In Comparative Example 4, unmodified chitosan was used as the outer shell; in Comparative Example 5, sodium tyrosine was not added to the outer shell; and in Comparative Example 3, the composite bacterial solution was loaded with biochar without outer shell coating. These methods resulted in decreased protection for the composite bacteria and a significantly lower viable bacteria retention rate. Therefore, this application, by first loading the composite bacteria with straw biochar and then coating them with an outer shell, can achieve greater protection of the composite bacteria, improve stability, and enhance soil remediation efficacy.

[0154] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. A soil remediation agent, characterized in that, The product comprises, by weight parts, the following raw materials: 15-20 parts microbial inoculant, 20-25 parts humic acid, 15-20 parts fulvic acid, 5-10 parts soybean meal extract, 1-1.5 parts seaweed extract, and 20-25 parts plant extract; wherein the microbial inoculant comprises a core composed of straw biochar and a compound bacterial solution, and an outer shell composed of polyethylene glycol monomethyl ether modified chitosan, sodium chelate, and sodium tripolyphosphate in a mass ratio of 1:(1.5-1.8):(0.3-0.5); the compound bacterial solution comprises Bacillus thuringiensis bacterial solution and Beauveria bassiana bacterial solution in a volume ratio of 10:(5-8); the plant extract is selected from at least one of Curcuma zedoaria extract, garlic extract, and Artemisia argyi extract; The straw biochar includes ginger straw pyrolysis biochar and jute straw pyrolysis biochar in a mass ratio of 1:(2-2.5); The preparation method of the seaweed extract includes the following steps: pulverizing seaweed, adding it to a mixed solution of sodium carbonate and sodium bicarbonate at a material-to-liquid ratio of (10-12):1, heating to 50-60℃ and stirring for 6-8 hours, cooling to room temperature, adjusting the pH to 7.5-8, adding a compound enzyme for enzymatic hydrolysis at a temperature of 30-40℃ for 2-4 hours, separating the solid and liquid, and concentrating under reduced pressure to obtain the seaweed extract; the compound enzyme is an alginate lyase and cellulase with a mass ratio of (2-3):

1.

2. The soil remediation agent according to claim 1, characterized in that, In the compound bacterial solution, the effective viable count of Bacillus thuringiensis bacterial solution is ≥500 million CFU / mL, and the effective viable count of Beauveria bassiana bacterial solution is ≥500 million CFU / mL.

3. The soil remediation agent according to claim 2, characterized in that, The compound bacterial solution also includes at least one of Bacillus subtilis, Bacillus licheniformis, Bacillus laterosporus, and actinomycetes.

4. The soil remediation agent according to claim 1, characterized in that, The mass-to-volume ratio of straw biochar and compound bacterial solution in the core is 1g:(3-5)mL.

5. The soil remediation agent according to any one of claims 1-4, characterized in that, The method for preparing the microbial inoculant includes the following steps: (1) After sterilizing the straw biochar, mix it with the compound bacterial solution, stir at low speed for 2-3 hours, and dry it until the moisture content is ≤10% to obtain biochar-loaded compound bacteria; (2) Place the biochar-loaded composite bacteria in a coating machine, mix polyethylene glycol monomethyl ether modified chitosan, sodium chelate, sodium tripolyphosphate and water to prepare a coating solution with a mass concentration of 2-3%, spray the coating solution by atomization, and dry it until the moisture content is ≤8% to obtain the coating solution.

6. The soil remediation agent according to claim 1, characterized in that, The method for preparing the soybean meal extract includes the following steps: adding soybean meal to water, boiling and maintaining for 10-20 minutes, then raising the temperature to 280-300°C and maintaining at this temperature for 10-15 minutes, cooling to room temperature, filtering, and drying the filtrate to obtain the soybean meal extract.

7. The method for preparing the soil remediation agent according to any one of claims 1-6, characterized in that, Includes the following steps: Mix the microbial agent, humic acid, fulvic acid, soybean meal extract, seaweed extract, and plant extract evenly, and dry until the moisture content is ≤10%.

8. The application of the soil remediation agent according to any one of claims 1-6 in preventing and controlling continuous cropping obstacles in ginger.

Images