A bio-organic fertilizer for remediation of heavy metal-contaminated soil and its preparation method

Abstract

The present invention provides a bio-organic fertilizer for remediating heavy metal-contaminated soil and a preparation method thereof, belonging to the field of fertilizer technology. The bio-organic fertilizer includes the following raw materials by weight: 15-20 parts chicken manure, 24-29 parts pig manure, 3-9 parts earthworm castings, 11-15 parts soybean meal, 20-25 parts modified biochar, 16-21 parts fermentation product of extraction residue, and 4-12 parts microbial agent. The bio-organic fertilizer prepared by the present invention for remediating heavy metal-contaminated soil can improve the pH of the soil, can continuously and effectively improve the physical and chemical properties of the soil, enhance the biological activity of the soil, and can effectively reduce the content of heavy metal elements in the soil, thereby achieving all-round regulation of the soil environment and promoting increased soybean yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic fertilizers, and in particular relates to a bio-organic fertilizer for repairing heavy metal-contaminated soil and a preparation method thereof. Background Art

[0002] Heavy metal pollution in farmland is an environmental phenomenon primarily caused by the excessive accumulation of heavy metal-containing waste in the soil. The main heavy metals involved in this type of pollution include elements with significant biological toxicity, such as mercury, cadmium, lead, chromium, and the metalloid arsenic, as well as elements with certain toxicity, such as zinc, copper, and nickel. Once these heavy metals enter farmland soil, they not only affect the ecological balance of the soil itself but can also affect human health through the food chain, resulting in serious consequences. Therefore, the prevention, control, and management of heavy metal pollution in farmland soil is particularly important. This not only affects the quality and safety of crops, but also directly affects people's dietary health and the sustainable development of the ecological environment.

[0003] Bio-organic fertilizer has significant advantages in treating heavy metal pollution in soil. It can not only effectively reduce the toxicity of heavy metals, but also improve soil quality and promote crop growth. It is an environmentally friendly soil remediation technology worthy of promotion and application.

[0004] Currently, there are many bio-organic fertilizers for the remediation of heavy metal contaminated soil. Although bio-organic fertilizers have shown many advantages in treating soil heavy metal pollution, they still face some technical and implementation challenges in actual application: (1) Unstable heavy metal fixation effect: Although bio-organic fertilizers can fix heavy metals by forming chelates or complexes, this fixation may be affected by environmental factors such as soil pH, temperature, and humidity, resulting in the reactivation of heavy metals, thereby weakening the remediation effect. (2) Selection and proportion of bio-organic fertilizers: Different types of bio-organic fertilizers have different adsorption and fixation capabilities for heavy metals. It is necessary to select the appropriate fertilizer type and reasonable application ratio based on the specific pollution situation of the soil and the needs of crops, which increases the difficulty of actual operation. (3) Maintenance of microbial activity: Beneficial microorganisms in bio-organic fertilizers are sensitive to environmental conditions. If the soil conditions are not suitable (such as extreme pH, drought or excessive moisture), the survival rate and activity of microorganisms may be affected, thereby affecting the remediation effect. (4) Limited heavy metal removal efficiency: Bio-organic fertilizers mainly reduce the bioavailability of heavy metals through fixation, rather than completely removing heavy metals from the soil. This means that once environmental conditions change, the fixed heavy metals may be released again, causing secondary pollution. (5) Uncertainty of long-term effects: The remediation of soil heavy metal pollution by bio-organic fertilizers is a long-term process, and its long-term effects and stability still need further research and verification, especially under different climatic conditions and different types of soil.

[0005] Chinese patent CN113480364B discloses an organic fertilizer for treating heavy metal pollution and its preparation method. The fertilizer comprises 10-20 parts by weight of fulvic acid, 5-10 parts by weight of vermiculite, 5-10 parts by weight of kaolinite, 10-20 parts by weight of biochar, 5-10 parts by weight of potassium fulvate, 15-30 parts by weight of organic fertilizer, and 5-12 parts by weight of a microbial agent. This method can be applied to the field of heavy metal removal. However, the heavy metal removal efficiency is limited and the yield-increasing effect on soybeans is poor.

[0006] Therefore, there is an urgent need for a bio-organic fertilizer for remediation of heavy metal contaminated soil and a preparation method thereof. Summary of the Invention

[0007] The purpose of the present invention is to provide a bio-organic fertilizer for remediating heavy metal contaminated soil and a preparation method thereof.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A bio-organic fertilizer for remediating heavy metal-contaminated soil, comprising the following raw materials in weight fractions: 15-20 parts of chicken manure, 24-29 parts of pig manure, 3-9 parts of earthworm castings, 11-15 parts of soybean meal, 20-25 parts of modified biochar, 16-21 parts of fermented extract residue, and 4-12 parts of microbial agent;

[0010] The preparation method of the extraction residue fermentation product comprises the following steps:

[0011] (1) crushing the residue extracted from the bark of Taxus cuspidata into particles with a particle size of 0.2-0.8 cm to obtain a fermentation raw material;

[0012] (2) Spraying the bacterial liquid onto the fermentation raw materials, mixing them evenly, and then stacking and fermenting them at room temperature. The piles are turned over every 7-10 days, and fermented for 4-6 weeks. The fermented materials are then air-dried to obtain the fermented extract residue.

[0013] Furthermore, the weight percentage of the bacterial liquid to the fermentation raw materials is 0.4-0.7%.

[0014] Furthermore, the method for preparing the bacterial solution comprises the following steps:

[0015] (1) The three strains were inoculated onto slant culture medium, and static cultured at 30-35°C for activation. The colonies were grown all over the slant, and three slant culture strains were obtained. The three strains were: Halomonas marinum, Aspergillus niger, and Trichoderma harzianum.

[0016] (2) The three slant cultured strains were inoculated into peptone liquid medium, respectively, and cultured at 35-38°C and 150-170 rpm for 20-25 h to obtain seed solutions of Halomonas marinum, Aspergillus niger, and Trichoderma harzianum, respectively;

[0017] (3) Inoculating the seed liquid of Halomonas marinum, the seed liquid of Aspergillus niger, and the seed liquid of Trichoderma harzianum into the same fermentation medium for aerobic fermentation to obtain a bacterial liquid.

[0018] Furthermore, in the step (3), the sea salt mononas seed solution is inoculated into the fermentation medium at an inoculation amount of 1.4%-1.8% by weight; the Aspergillus niger seed solution is inoculated into the fermentation medium at an inoculation amount of 1.3%-1.6% by weight, and the Trichoderma harzianum seed solution is inoculated into the fermentation medium at an inoculation amount of 0.6%-0.9% by weight.

[0019] Paclitaxel, extracted from the bark of the Northeast Yew (T. CUSPIDATA STEBIUCC (Bark)), is an important anticancer drug. However, the bark residue after paclitaxel extraction is discarded as waste and causes environmental pollution. The present invention uses the bark residue after paclitaxel extraction as raw material for fermentation using a specific bacterial solution, which can improve the organic matter content of saline-alkali soil. Analysis shows that the bark residue after paclitaxel extraction is rich in organic matter and can be converted into high-quality organic fertilizer after fermentation. The organic acids, amino acids, polysaccharides, and other substances produced during the fermentation process can improve the physical and chemical properties of the soil and increase its organic matter content. The specific bacterial solution can promote the decomposition of organic matter and produce more beneficial metabolites. These microorganisms can also inhibit the growth of harmful microorganisms and enhance the biological activity of the soil. The organic acids produced during the fermentation process can react with salt in the soil to form more stable compounds, reducing the salt content of the soil. It can also improve the vitality of the bacteria in the microbial inoculant.

[0020] Furthermore, the microbial agent includes Pseudomonas paraxanthomonas, Bacillus subtilis and Bacillus amyloliquefaciens.

[0021] Furthermore, the bacterial activity of the Pseudomonas paraxanthinosa in the microbial agent is 10 9 CFU / g-10 10 CFU / g; the bacterial activity of Bacillus subtilis in the microbial agent is 10 8 CFU / g-10 9 CFU / g; the bacterial activity of Bacillus amyloliquefaciens in the mixed solution is 10 6 CFU / g-10 7 CFU / g.

[0022] The present invention attempts to use Pseudomonas paraflavonoids, which has good salt and alkali tolerance, to improve the content of heavy metal elements in the soil, but the effect is not ideal. The present invention prepares a microbial agent by adding three composite bacterial strains, which can reduce the content of heavy metal elements in the soil. Mainly, the three microbial bacteria can increase the organic matter content of the soil and improve the soil's water and fertilizer retention capacity through synergistic action. The good soil structure helps to reduce the migration and diffusion of heavy metals, making them more difficult to be absorbed by plant roots. At the same time, the microbial agent can decompose organic matter, releasing a variety of enzymes and metabolites, which can form insoluble complexes with heavy metals, further promoting the fixation and conversion of heavy metals.

[0023] Furthermore, when the microbial agent includes specific active Pseudomonas paraxanthomonas, Bacillus subtilis and Bacillus amyloliquefaciens, and the bacterial liquid uses three seed liquids with specific inoculation amounts, the heavy metal content in soybean seeds can be reduced.

[0024] Furthermore, the preparation method of the modified biochar comprises the following steps:

[0025] (1) Coconut shells were crushed and passed through a 160-mesh sieve, dried at 105-110° C. for 15-20 h, and subjected to microwave cracking under nitrogen at a cracking temperature of 700-750° C. for 4-5 h to obtain biochar;

[0026] (2) adding 1 part by weight of biochar to 8-10 parts by weight of 60-70 (v / v)% ethanol aqueous solution, adding 0.06-0.1 parts by weight of silane coupling agent KH570, heating at 50-60° C. for 4-6 hours, filtering, washing, and drying to obtain amination biochar;

[0027] (3) Amination-modified biochar, dimethylformamide, cysteine, and triethylamine in a weight ratio of 10:(50-55):(1-1.5):(4-6) are mixed and stirred for reaction at a temperature of 80-85°C for 2-3 hours. After the reaction is completed, the mixture is filtered, washed, and dried to obtain modified biochar.

[0028] This invention attempts to add biochar to organic fertilizer to improve its long-term effectiveness in reducing heavy metal content in soil, but the results are unsatisfactory. By modifying the biochar, the invention can improve soil pH and increase soil biodiversity. The analysis is based on the fact that by grafting cysteine ​​onto the biochar, the sulfhydryl groups can coordinate with heavy metal ions. Simultaneously, the modified biochar can adsorb and slowly release nutrients from the fertilizer, reducing nutrient loss and providing a good habitat for the microorganisms in the biofertilizer.

[0029] The present invention provides a method for preparing the bio-organic fertilizer for remediating heavy metal contaminated soil, comprising the following steps: weighing raw materials by weight, adding the raw materials into a granulator, spraying water accounting for 20-25% of the total weight of the raw materials, mixing and granulating, and obtaining the bio-organic fertilizer for remediating heavy metal contaminated soil.

[0030] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0031] 1. The present invention uses the bark residue after paclitaxel extraction as raw material and ferments it using a specific bacterial solution, which can improve the organic matter content of saline-alkali land.

[0032] 2. The present invention can reduce the content of heavy metal elements in the soil by adding microbial agents.

[0033] 3. The present invention can improve soil pH and increase soil biological richness by modifying biochar.

[0034] 4. When the microbial agent includes specific active species of Pseudomonas paraxanthomonas, Bacillus subtilis and Bacillus amyloliquefaciens, and the bacterial solution uses three seed solutions with specific inoculation amounts, the heavy metal content in soybean seeds can be reduced. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] The raw materials used in the following examples of the present invention are all commercially available commodities:

[0037] Slant culture medium was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: R22702 slant culture medium (containing agar).

[0038] Beef extract peptone liquid medium was purchased from Beijing Hongrun Baoshun Technology Co., Ltd.

[0039] The fermentation medium comprises the following components: 8 g / L glucose, 7 g / L peptone, 2 g / L ammonium sulfate, 1 g / L magnesium sulfate heptahydrate, 0.5 g / L potassium dihydrogen phosphate, 1 g / L dipotassium hydrogen phosphate, 1.5 g / L sodium chloride and 3 g / L sodium selenite, with a pH of 7.2.

[0040] The residue extracted from the bark of Taxus cuspidata was provided by Shenyang Tianfeng Biopharmaceutical Co., Ltd.

[0041] Halomonas maritima, number: SHBCC D51878, was purchased from Shanghai Collection of Microorganisms.

[0042] Trichoderma harzianum, number: SHBCC D67935, was purchased from Shanghai Microbiological Collection Center.

[0043] Aspergillus niger, number SHBCC D22387, was purchased from Shanghai Collection of Microorganisms.

[0044] Pseudomonas paraxanthinus, number: SHBCC D70400, was purchased from Shanghai Microbiological Collection Center.

[0045] Bacillus subtilis, number: SHBCC D71862, was purchased from Shanghai Microbiological Collection Center.

[0046] Bacillus amyloliquefaciens, number: SHBCC D52950, ​​was purchased from Shanghai Microbiological Collection Center.

[0047] Example 1

[0048] This embodiment provides a bio-organic fertilizer for remediating heavy metal contaminated soil, comprising the following raw materials by weight: 18 parts chicken manure, 26 parts pig manure, 7 parts earthworm castings, 12 parts soybean meal, 22 parts modified biochar, 18 parts fermentation product of extraction residue, and 8 parts microbial agent;

[0049] The preparation method of the extraction residue fermentation product comprises the following steps:

[0050] (1) crushing the residue extracted from the bark of Taxus cuspidata into particles with a particle size of 0.2-0.8 cm to obtain a fermentation raw material;

[0051] (2) Spraying bacterial liquid onto the fermentation raw materials, with the bacterial liquid amount accounting for 0.6% by weight of the fermentation raw materials. After uniform mixing, the fermentation was carried out at room temperature, with the pile turned over once every 8 days, and the fermentation was continued for 5 weeks, followed by air drying to obtain the fermentation residue.

[0052] The preparation method of the bacterial liquid comprises the following steps:

[0053] (1) The three strains were inoculated onto slant culture medium, and activated by static culture at 32°C. After the colonies covered the slant, three slant culture strains were obtained; the three strains were: Halomonas marinum, Aspergillus niger, and Trichoderma harzianum;

[0054] (2) The three slant cultured strains were inoculated into peptone liquid medium, and cultured at 37°C and 160 rpm for 23 h to obtain seed solutions of Halomonas marinum, Aspergillus niger, and Trichoderma harzianum, respectively;

[0055] (3) Inoculating the seed liquid of Halomonas marinum, the seed liquid of Aspergillus niger, and the seed liquid of Trichoderma harzianum into the same fermentation medium for aerobic fermentation to obtain a bacterial liquid.

[0056] In the step (3), the sea salt mononas seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.6% by weight; the Aspergillus niger seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.5% by weight, and the Trichoderma harzianum seed liquid is inoculated into the fermentation medium at an inoculation rate of 0.7% by weight.

[0057] The microbial agent includes Pseudomonas paraxanthophylla, Bacillus subtilis and Bacillus amyloliquefaciens. The bacterial activity of Pseudomonas paraxanthophylla in the microbial agent is 10 10 CFU / g; the bacterial activity of Bacillus subtilis in the microbial agent is 10 8 CFU / g; the bacterial activity of Bacillus amyloliquefaciens in the mixed solution is 10 7 CFU / g.

[0058] The preparation method of the modified biochar comprises the following steps:

[0059] (1) Coconut shells were crushed and passed through a 160-mesh sieve, dried at 108°C for 18 h, and microwave-crackered under nitrogen at a temperature of 720°C for 4.5 h to obtain biochar;

[0060] (2) adding 1 part by weight of biochar to 9 parts by weight of 65 (v / v)% ethanol aqueous solution, adding 0.08 parts by weight of silane coupling agent KH570, heating at 55°C for 5 hours, filtering, washing, and drying to obtain amino-treated biochar;

[0061] (3) Amination-modified biochar, dimethylformamide, cysteine, and triethylamine in a weight ratio of 10:52:1.2:5 were mixed and stirred for reaction at 82°C for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar.

[0062] The method for preparing the bio-organic fertilizer for remediating heavy metal contaminated soil comprises the following steps: weighing raw materials by weight, adding the raw materials into a granulator, spraying water accounting for 22% of the total weight of the raw materials, mixing and granulating the raw materials, and obtaining the bio-organic fertilizer for remediating heavy metal contaminated soil.

[0063] Example 2

[0064] This embodiment provides a bio-organic fertilizer for remediating heavy metal contaminated soil, comprising the following raw materials by weight: 15 parts chicken manure, 29 parts pig manure, 3 parts earthworm castings, 15 parts soybean meal, 20 parts modified biochar, 21 parts fermentation product of extraction residue, and 12 parts microbial agent;

[0065] The preparation method of the extraction residue fermentation product comprises the following steps:

[0066] (1) crushing the residue extracted from the bark of Taxus cuspidata into particles with a particle size of 0.2-0.8 cm to obtain a fermentation raw material;

[0067] (2) Spraying bacterial liquid onto the fermentation raw materials, with the bacterial liquid amount accounting for 0.7% by weight of the fermentation raw materials. After uniform mixing, the fermentation was carried out at room temperature, with the pile turned over once every 7 days, and fermented for 6 weeks, and then air-dried to obtain the fermentation residue.

[0068] The preparation method of the bacterial liquid comprises the following steps:

[0069] (1) The three strains were inoculated onto slant culture medium, and activated by static culture at 30°C. After the colonies covered the slant, three slant culture strains were obtained; the three strains were: Halomonas marinum, Aspergillus niger, and Trichoderma harzianum;

[0070] (2) The three slant cultured strains were inoculated into peptone liquid medium, and cultured at 38°C and 150 rpm for 25 h to obtain seed solutions of Halomonas marinum, Aspergillus niger, and Trichoderma harzianum, respectively;

[0071] (3) Inoculating the seed liquid of Halomonas marinum, the seed liquid of Aspergillus niger, and the seed liquid of Trichoderma harzianum into the same fermentation medium for aerobic fermentation to obtain a bacterial liquid.

[0072] In the step (3), the sea salt mononas seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.4% by weight; the Aspergillus niger seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.6% by weight, and the Trichoderma harzianum seed liquid is inoculated into the fermentation medium at an inoculation rate of 0.6% by weight.

[0073] The microbial agent includes Pseudomonas paraxanthophylla, Bacillus subtilis and Bacillus amyloliquefaciens. The bacterial activity of Pseudomonas paraxanthophylla in the microbial agent is 10 9 CFU / g; the bacterial activity of Bacillus subtilis in the microbial agent is 10 9 CFU / g; the bacterial activity of Bacillus amyloliquefaciens in the mixed solution is 10 6 CFU / g.

[0074] The preparation method of the modified biochar comprises the following steps:

[0075] (1) Coconut shells were crushed and passed through a 160-mesh sieve, dried at 105°C for 20 h, and microwave-cracked under nitrogen at a temperature of 700°C for 5 h to obtain biochar;

[0076] (2) adding 1 part by weight of biochar to 8 parts by weight of 70 (v / v)% ethanol aqueous solution, adding 0.1 parts by weight of silane coupling agent KH570, heating at 50°C for 6 hours, filtering, washing, and drying to obtain amino-treated biochar;

[0077] (3) Amination-modified biochar, dimethylformamide, cysteine, and triethylamine in a weight ratio of 10:55:1:6 were mixed and stirred for reaction at 80°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified biochar.

[0078] The method for preparing the bio-organic fertilizer for remediating heavy metal contaminated soil comprises the following steps: weighing raw materials by weight, adding the raw materials into a granulator, spraying water accounting for 20% of the total weight of the raw materials, mixing and granulating the raw materials, and obtaining the bio-organic fertilizer for remediating heavy metal contaminated soil.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is: a biological organic fertilizer for remediation of heavy metal contaminated soil, comprising the following raw materials by weight: 26 parts of chicken manure, 18 parts of pig manure, 12 parts of earthworm castings, 7 parts of soybean meal, 12 parts of modified biochar, 23 parts of extraction residue fermentation product, and 13 parts of microbial agent.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that: Halomonas marinum is replaced by Trichoderma viride (No.: SHBCCD13179, purchased from Shanghai Collection of Microorganisms Center), Aspergillus niger is replaced by Aspergillus cinnamomea (No.: SHBCC D18581, purchased from Shanghai Collection of Microorganisms Center), and Trichoderma harzianum is replaced by Trichoderma koningii (No.: SHBCC D11491, purchased from Shanghai Collection of Microorganisms Center).

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that in the step (3), the sea salt mononas seed liquid is inoculated into the fermentation medium at an inoculum amount of 0.7% by weight; the Aspergillus niger seed liquid is inoculated into the fermentation medium at an inoculum amount of 1.0% by weight, and the Trichoderma harzianum seed liquid is inoculated into the fermentation medium at an inoculum amount of 2.2% by weight.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 1 is that the microbial agent includes Pseudomonas paraxanthophylloides, Bacillus subtilis and Bacillus amyloliquefaciens. The bacterial activity of Pseudomonas paraxanthophylloides in the microbial agent is 10 7 CFU / g; the bacterial activity of Bacillus subtilis in the microbial agent is 1010 CFU / g; the bacterial activity of Bacillus amyloliquefaciens in the mixed solution is 10 8 CFU / g.

[0087] Comparative Example 5

[0088] The difference between this comparative example and Example 1 is that the microbial agent is Pseudomonas paraxanthus; the bacterial activity of Pseudomonas paraxanthus in the microbial agent is 2×10 10 CFU / g.

[0089] Comparative Example 6

[0090] The difference between this comparative example and Example 1 is that the biochar is not modified.

[0091] The biochar preparation method comprises the following steps: crushing coconut shells and passing them through a 160-mesh sieve, drying them at 108° C. for 18 hours, and performing microwave cracking under nitrogen conditions at a cracking temperature of 720° C. for 4.5 hours to obtain biochar.

[0092] Performance Testing

[0093] The bio-organic fertilizers prepared in Examples 1-2 and Comparative Examples 1-6 were subjected to performance tests.

[0094] Experimental site: Located in a saline-alkali land in Da'an City, Jilin Province, randomly divided into 9 experimental plots.

[0095] Test crop: Heinong 87 soybean.

[0096] Experimental setup: The experimental group was conventional fertilization + the bio-organic fertilizer of the present invention, with an application rate of 40 kg / mu of bio-organic fertilizer, and the control group was conventional fertilization + 40 kg / mu of conventional fertilizer;

[0097] Test method: After soybean harvest, collect 0-20cm surface soil and mix thoroughly. Some soil samples are placed in sterile bags, frozen with ice, and then brought back to the laboratory and stored in a -80℃ refrigerator for the determination of soil microbial diversity and community structure. The remaining soil samples are air-dried, ground and sieved for the determination of soil physical and chemical properties.

[0098] Soil pH was measured using a pH meter after extraction with a water-soil ratio of 2.5:1.

[0099] Calculate soybean yield and heavy metal content in soybean kernels.

[0100] The results are shown in Table 1-2.

[0101] Table 1 Changes in heavy metal content in soil

[0102]

[0103] Table 2 Soybean yield and heavy metal determination in grains

[0104]

[0105]

[0106] Note: / represents not tested.

[0107] As can be seen from the test data in Tables 1-2, the bio-organic fertilizers of Examples 1-2 of the present invention can improve soil available nutrients and biological activity while reducing the levels of four heavy metal elements: cadmium, mercury, copper, and lead. They also improved soybean yield and the heavy metal content in soybean grains.

[0108] However, the comparative examples, because they did not adopt the necessary technical solutions, performed significantly worse than the examples in the corresponding performance tests. In Comparative Example 1, the raw material composition of the bio-organic fertilizer was different, resulting in a reduced effect on heavy metal abatement and lower soybean yield. In Comparative Example 2, the fermentation of the bark residue after paclitaxel extraction used a different bacterial solution, which showed a decrease in the organic matter content of the saline-alkali soil. In Comparative Example 3, the inoculation rates of the three bacterial species in the bacterial solution were different, which showed an increase in the heavy metal content in the soybeans. In Comparative Example 4, the amount of microbial agent was different, which showed an increase in the heavy metal content in the soybeans. In Comparative Example 5, only one microbial agent was used, which showed an increase in the heavy metal content in the soil. In Comparative Example 6, the biochar was not modified, which reduced the soil biodiversity. These experimental results further demonstrate the importance of the technical solutions defined in the present invention for its technical effectiveness.

[0109] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A bio-organic fertilizer for remediation of heavy metal contaminated soil, characterized in that: The raw materials include the following weight fractions: 15-20 parts of chicken manure, 24-29 parts of pig manure, 3-9 parts of earthworm manure, 11-15 parts of soybean meal, 20-25 parts of modified biochar, 16-21 parts of extraction residue fermentation product, and 4-12 parts of microbial agent; The preparation method of the extraction residue fermentation product comprises: (1) Grinding the residue extracted from the bark of the northeastern yew into particles with a particle size of 0.2-0.8 cm to obtain a fermentation raw material; (2) Spraying the bacterial liquid onto the fermentation raw materials, mixing them evenly, and then fermenting them at room temperature. The piles are turned over every 7-10 days, and fermented for 4-6 weeks. The fermented materials are then air-dried to obtain the fermentation residues. The preparation method of the bacterial solution includes: (1) The three strains were inoculated onto slant culture medium respectively, and static culture was activated at 30-35°C. When the colonies covered the slant, three slant culture strains were obtained; the three strains were: Halomonas marinum, Aspergillus niger, and Trichoderma harzianum; (2) The three slant cultured strains were inoculated into peptone liquid medium, respectively, and cultured at 35-38°C and 150-170 rpm for 20-25 h to obtain seed liquids of Halomonas marinum, Aspergillus niger, and Trichoderma harzianum, respectively; (3) inoculating the seed liquid of Halomonas marinum, the seed liquid of Aspergillus niger, and the seed liquid of Trichoderma harzianum into the same fermentation medium, and performing aerobic fermentation to obtain a bacterial liquid; The preparation method of modified biochar includes: (1) Coconut shells were crushed and passed through a 160-mesh sieve, dried at 105-110°C for 15-20h, and subjected to microwave cracking under nitrogen to obtain biochar; (2) adding 1 part by weight of biochar to 8-10 parts by weight of 60-70 (v / v)% ethanol aqueous solution, adding 0.06-0.1 parts by weight of silane coupling agent KH570, heating at 50-60°C for 4-6 hours, filtering, washing, and drying to obtain amino-treated biochar; (3) Mixing the amination biochar, dimethylformamide, cysteine, and triethylamine in a weight ratio of 10: (50-55): (1-1.5): (4-6), stirring and reacting at a temperature of 80-85 ° C for 2-3 h. After the reaction is completed, filtering, washing, and drying to obtain modified biochar; Microbial agents include Pseudomonas paraxanthus, Bacillus subtilis and Bacillus amyloliquefaciens.

2. The bio-organic fertilizer for remediation of heavy metal contaminated soil according to claim 1, characterized in that: The weight percentage of the bacterial liquid to the fermentation raw materials is 0.4-0.7%.

3. The bio-organic fertilizer for remediation of heavy metal contaminated soil according to claim 2, characterized in that: In the step (3), the sea salt mononas seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.4%-1.8% by weight; the Aspergillus niger seed liquid is inoculated into the fermentation medium at an inoculation rate of 1.3%-1.6% by weight; and the Trichoderma harzianum seed liquid is inoculated into the fermentation medium at an inoculation rate of 0.6%-0.9% by weight.

4. The bio-organic fertilizer for remediation of heavy metal contaminated soil according to claim 3, characterized in that: The bacterial activity of Pseudomonas paraxanthin in the microbial agent is 10 9 CFU / g-10 10 CFU / g; the bacterial activity of Bacillus subtilis in the microbial agent is 10 8 CFU / g-10 9 CFU / g; the bacterial activity of Bacillus amyloliquefaciens in the mixed solution is 10 6 CFU / g-10 7 CFU / g.

5. The bio-organic fertilizer for remediation of heavy metal contaminated soil according to claim 4, characterized in that: Microwave pyrolysis conditions are: pyrolysis temperature 700-750℃, pyrolysis time 4-5h, 6. A method for preparing a bio-organic fertilizer for remediation of heavy metal contaminated soil according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: weighing raw materials by weight, adding the raw materials into a granulator, spraying water accounting for 20-25% of the total weight of the raw materials, mixing and granulating, and obtaining a bio-organic fertilizer for repairing heavy metal contaminated soil.

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