Biomass charcoal seed coating agent and preparation method thereof

Abstract

The invention relates to the technical field of seed coating agent production, in particular to a biomass charcoal seed coating agent and a preparation method thereof. The biomass charcoal seed coating agent is prepared from the following raw materials in parts by weight: 20-30 parts of composite biomass charcoal, 3-6 parts of a functional aid, 3-5 parts of a film-forming agent, 2-4 parts of ethylene glycol, 4-7 parts of potassium benzoate, 2-6 parts of sorbic acid and 30-50 parts of water, a film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water are put into mixing equipment to be mixed and stirred, ball milling is performed after uniform mixing, then composite biomass charcoal and a functional additive are added into the mixture, stirring and mixing are continued, discharging is performed after mixing is completed, and then inspection, metering and packaging procedures are performed in sequence to obtain the environment-friendly biomass charcoal composite material. And finally preparing a finished product of the biomass charcoal seed coating agent. The seed coating agent not only has a better function of improving the emergence rate of crops, but also has a function of promoting the growth of the crops, and also has an excellent pest control effect, so that the quality of the crops is effectively ensured.

Description

Technical Field

[0001] The invention relates to the technical field of seed coating agent production, in particular to a biomass charcoal seed coating agent and a preparation method thereof. Background Art

[0002] Seed coating agents are available in liquid and solid powder form. Some are prefabricated for long-term storage, while others are made and used immediately. They are developed on the basis of suspensions, powders, and wettable powders. The active ingredients are required to be gradually released without any toxic effects on the germination and growth of crops. The seed coating film is water-permeable and air-permeable, and does not affect the life and respiration of seeds. Seed coating agents are highly efficient, economical, safe, long-lasting, and multifunctional.

[0003] In the patent document with application number "CN202211732778.2" and name "A biochar seed coating agent and its preparation method", it is recorded that "the biochar seed coating agent includes biochar, wood vinegar extract, sodium 5-nitroguaiacol and chitosan, and the weight ratio is 1:5-15:0.1:0.23. The present invention also discloses the preparation method and use of the above-mentioned biochar seed coating agent. The present invention makes full use of agricultural and forestry organic waste to prepare biochar and wood vinegar extract, and then mixes biochar, wood vinegar extract, sodium 5-nitroguaiacol and chitosan in a specific proportion, which can improve the germination rate of seeds, provide protection for agricultural seeds, and reduce environmental pollution to a certain extent, and has good social and economic effects". Although the manufactured biochar seed coating agent has certain advantages such as improving the germination rate of seeds, its own pest control and crop growth promotion performance is relatively insufficient.

[0004] For example, the patent document with application number "CN201510330497.8" and name "Compound seed coating agent for preventing and controlling corn sheath blight" records that "the compound seed coating agent includes the following components in weight percentage: 0.05-1% of phoxim, 0.1-1% of chlorpyrifos, 0.01-0.1% of validamycin, 5-15% of film-forming agent, 0.01-0.1% of trace elements, 0.01-0.1% of growth promoter, and 83-94% of water. The beneficial effects of the present invention are as follows: the seed coating agent of the present invention has the characteristics of convenient preparation, uniform coating, low shedding rate, high efficiency and low toxicity, and is relatively safe to the environment. It has good preventive effect on soil-borne diseases such as corn sheath blight". Although the manufactured compound seed coating agent has the advantages of disease prevention effect, it uses a variety of chemical substances to achieve disease prevention effect.

[0005] Based on this, the present invention provides a biomass charcoal seed coating agent and a preparation method thereof to solve the above-mentioned technical problems. Summary of the invention

[0006] The object of the present invention is to provide a biomass charcoal seed coating agent and a preparation method thereof. The prepared biomass charcoal seed coating agent not only has a good function of improving the emergence rate of crops, but also has a function of promoting the growth of crops. At the same time, it also has an excellent disease and pest control effect, effectively ensuring its quality.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The first aspect of the present invention provides a biochar seed coating agent, which is composed of the following raw materials in parts by weight: 20 to 30 parts of composite biochar, 3 to 6 parts of functional additives, 3 to 5 parts of film-forming agents, 2 to 4 parts of ethylene glycol, 4 to 7 parts of potassium benzoate, 2 to 6 parts of sorbic acid and 30 to 50 parts of water.

[0009] The present invention is further configured as follows: the preparation process of the composite biochar is as follows:

[0010] The first substrate is placed in deionized water for ultrasonic treatment at a solid-liquid ratio of 0.02 to 0.12 g / mL for 20 to 30 minutes, and a second substrate of 380 to 400% of the mass of the first substrate is added thereto, and the mixture is oscillated at a constant temperature of 30 to 35° C. and 200 r / min for 30 to 40 minutes;

[0011] After the constant temperature oscillation is completed, the mixture is filtered and then dried at a temperature of 70 to 100° C. to a constant weight to obtain composite biochar.

[0012] The present invention is further configured as follows: the preparation process of the first substrate is as follows:

[0013] The rice straw is crushed into 40-60 meshes, and dried in air at 100°C to a constant weight to obtain straw powder;

[0014] The straw powder is placed in a sodium hydroxide solution with a mass concentration of 22 to 25% at a solid-liquid ratio of 0.2 to 0.8 g / mL, and treated at 110 to 120° C. for 100 to 120 minutes. After suction filtration, a sulfuric acid solution with a mass concentration of 8% is added to the obtained filtrate at 62 to 65° C. until the pH value reaches 2.1 to 2.3. After suction filtration, the obtained filter cake is centrifuged at 5200 to 5600 r / min for 10 to 20 minutes, and the centrifugal product is washed 2 to 4 times with a sulfuric acid solution with a mass concentration of 8%, and then freeze-dried to obtain a first substrate.

[0015] The present invention is further configured as follows: the preparation process of the second substrate is as follows:

[0016] The composite powder is placed in a sodium hydroxide solution with a mass concentration of 32-35% at a solid-liquid ratio of 0.08-0.2 g / mL, treated at 80-100 r / min for 5-10 minutes, and then left to stand for 6-7 hours;

[0017] The dried product was placed in a tube furnace, heated from room temperature to 610-620°C at a heating rate of 6°C / min in a nitrogen atmosphere, and kept warm for 180-200 min;

[0018] After the heat preservation is completed, the ground product is ground and washed with deionized water for 2 to 6 times. Finally, it is dried at a temperature of 70 to 100° C. to a constant weight to obtain a second substrate.

[0019] The present invention is further configured as follows: the composite powder is prepared by mixing Lantana camara stem powder and Water hyacinth leaf powder in a mass ratio of 1:0.2-0.4.

[0020] The present invention is further configured as follows: the functional additive is prepared by mixing fertilizer solution and violet pigment in a mass ratio of 1:0.08-0.12.

[0021] The present invention is further configured as follows: the fertilizer solution is formed by mixing rubidium sulfate and water at a solid-liquid ratio of 0.01 to 0.05 g / mL.

[0022] A further configuration of the present invention is that the film-forming agent is selected from any one of 805 film-forming agent, 851 film-forming agent and 853 film-forming agent.

[0023] The second aspect of the present invention: also provides a method for preparing the above-mentioned biochar seed coating agent, comprising the following steps:

[0024] Step 1, accurately weigh the composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water, and put the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water into a mixing device for mixing and stirring, and ball mill after mixing evenly;

[0025] Step 2: After the ball milling is completed, add the composite biochar and functional additives, and continue to stir and mix;

[0026] Step 3: After the mixing is completed, the material is discharged, and then it is inspected and packaged in sequence to finally obtain the finished product of the biomass charcoal seed coating agent.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the present invention, composite biochar, functional additives, film-forming agents, ethylene glycol, potassium benzoate, sorbic acid and water are used as raw materials. Film-forming agents, ethylene glycol, potassium benzoate, sorbic acid and water are put into a mixing device for mixing and stirring. After being evenly mixed, they are ball-milled, and then composite biochar and functional additives are added thereto. Stirring and mixing are continued. After the mixing is completed, the materials are discharged, and then the inspection and metering packaging processes are carried out in sequence to finally obtain the finished product of the biochar seed coating agent. The biochar seed coating agent prepared by the present invention not only has a good function of improving the emergence rate of crops, but also has a function of promoting the growth of crops. At the same time, it also has an excellent disease and pest control effect, and effectively guarantees its quality. The biochar seed coating agent and its preparation method provided by the present invention have a broader market prospect and are more suitable for promotion. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] The present embodiment provides a biochar seed coating agent, which is composed of the following raw materials in parts by weight: 20 parts of composite biochar, 3 parts of functional additives, 3 parts of film-forming agents, 2 parts of ethylene glycol, 4 parts of potassium benzoate, 2 parts of sorbic acid and 30 parts of water.

[0032] The preparation process of composite biochar is as follows:

[0033] The first substrate was placed in deionized water for ultrasonic treatment at a solid-liquid ratio of 0.02 g / mL for 20 minutes, and a second substrate with a mass of 380% of the first substrate was added thereto, and the mixture was oscillated at a constant temperature of 30° C. and 200 r / min for 30 minutes;

[0034] After the constant temperature oscillation is completed, the mixture is filtered and then dried at 70° C. to a constant weight to obtain composite biochar.

[0035] Furthermore, the preparation process of the first substrate is as follows:

[0036] The rice straw was crushed into 40 meshes, and dried in air at 100°C to a constant weight to obtain straw powder;

[0037] The straw powder was placed in a sodium hydroxide solution with a mass concentration of 22% at a solid-liquid ratio of 0.2 g / mL, and treated at 110° C. for 100 minutes. After filtration, a sulfuric acid solution with a mass concentration of 8% was added to the obtained filtrate at 62° C. until the pH value reached 2.1. After filtration, the obtained filter cake was centrifuged at 5200 r / min for 10 minutes. The centrifuged product was washed twice with a sulfuric acid solution with a mass concentration of 8%, and then freeze-dried to obtain a first substrate.

[0038] In addition, the preparation process of the second substrate is as follows:

[0039] The composite powder was placed in a sodium hydroxide solution with a mass concentration of 32% at a solid-liquid ratio of 0.08 g / mL, treated at 80 r / min for 5 minutes, and then left to stand for 6 hours;

[0040] The dried product was placed in a tube furnace and heated from room temperature to 610°C at a rate of 6°C / min in a nitrogen atmosphere for 180 min.

[0041] After the heat preservation is completed, the product is ground and washed twice with deionized water. Finally, it is dried at 70° C. to a constant weight to obtain a second substrate.

[0042] Furthermore, the composite powder is prepared by mixing Lantana camara stem powder and Water hyacinth leaf powder in a mass ratio of 1:0.2.

[0043] The functional additive is prepared by mixing fertilizer solution and violet pigment in a mass ratio of 1:0.08.

[0044] Furthermore, the fertilizer solution is prepared by mixing rubidium sulfate and water at a solid-liquid ratio of 0.01 g / mL.

[0045] The film-forming agent used is 805 film-forming agent.

[0046] In addition, this embodiment also provides a method for preparing the above-mentioned biochar seed coating agent, comprising the following steps:

[0047] Step 1, accurately weigh the composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water, and put the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water into a mixing device for mixing and stirring, and ball mill after mixing evenly;

[0048] Step 2: After the ball milling is completed, add the composite biochar and functional additives, and continue to stir and mix;

[0049] Step 3: After the mixing is completed, the material is discharged, and then it is inspected and packaged in sequence to finally obtain the finished product of the biomass charcoal seed coating agent.

[0050] Example 2

[0051] The preparation method of the biochar seed coating agent provided in this embodiment is basically the same as that in Example 1, except that: the specific raw material composition and the specific preparation method of the biochar seed coating agent in this embodiment are different; the specific raw material composition and the specific preparation method of the biochar seed coating agent in this embodiment are as follows:

[0052] A biochar seed coating agent is composed of the following raw materials in parts by weight: 25 parts of composite biochar, 4 parts of functional additives, 4 parts of film-forming agents, 3 parts of ethylene glycol, 5 parts of potassium benzoate, 4 parts of sorbic acid and 40 parts of water.

[0053] The preparation process of composite biochar is as follows:

[0054] The first substrate was placed in deionized water for ultrasonic treatment at a solid-liquid ratio of 0.07 g / mL for 25 minutes, and a second substrate with a mass of 390% of the first substrate was added thereto, and the mixture was oscillated at a constant temperature of 32° C. and 200 r / min for 35 minutes;

[0055] After the constant temperature oscillation is completed, the mixture is filtered and then dried at 85° C. to a constant weight to obtain composite biochar.

[0056] Furthermore, the preparation process of the first substrate is as follows:

[0057] The rice straw was crushed into 50 meshes, and dried in air at 100°C to a constant weight to obtain straw powder;

[0058] The straw powder was placed in a sodium hydroxide solution with a mass concentration of 23% at a solid-liquid ratio of 0.4 g / mL, and treated at 115° C. for 110 minutes. After filtration, a sulfuric acid solution with a mass concentration of 8% was added to the obtained filtrate at 63° C. until the pH value reached 2.2. After filtration, the obtained filter cake was centrifuged at 5400 r / min for 15 minutes. The centrifuged product was washed three times with a sulfuric acid solution with a mass concentration of 8%, and then freeze-dried to obtain a first substrate.

[0059] In addition, the preparation process of the second substrate is as follows:

[0060] The composite powder was placed in a sodium hydroxide solution with a mass concentration of 33% at a solid-liquid ratio of 0.11 g / mL, treated at 90 r / min for 7 minutes, and then left to stand for 7 hours;

[0061] The dried product was taken out and dried. The dried product was placed in a tube furnace and heated from room temperature to 615°C at a heating rate of 6°C / min in a nitrogen atmosphere and kept warm for 190 min.

[0062] After the heat preservation is completed, the product is ground and washed four times with deionized water. Finally, it is dried at 785° C. to a constant weight to obtain a second substrate.

[0063] Furthermore, the composite powder is prepared by mixing Lantana camara stem powder and Water hyacinth leaf powder in a mass ratio of 1:0.3.

[0064] The functional additive is prepared by mixing fertilizer solution and violet pigment in a mass ratio of 1:0.1.

[0065] Furthermore, the fertilizer solution is prepared by mixing rubidium sulfate and water at a solid-liquid ratio of 0.03 g / mL.

[0066] The film-forming agent used is 851 film-forming agent.

[0067] In addition, this embodiment also provides a method for preparing the above-mentioned biochar seed coating agent, comprising the following steps:

[0068] Step 1, accurately weigh the composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water, and put the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water into a mixing device for mixing and stirring, and ball mill after mixing evenly;

[0069] Step 2: After the ball milling is completed, add the composite biochar and functional additives, and continue to stir and mix;

[0070] Step 3: After the mixing is completed, the material is discharged, and then it is inspected and packaged in sequence to finally obtain the finished product of the biomass charcoal seed coating agent.

[0071] Example 3

[0072] The preparation method of the biochar seed coating agent provided in this embodiment is basically the same as that in Example 1, except that: the specific raw material composition and the specific preparation method of the biochar seed coating agent in this embodiment are different; the specific raw material composition and the specific preparation method of the biochar seed coating agent in this embodiment are as follows:

[0073] A biochar seed coating agent is composed of the following raw materials in parts by weight: 30 parts of composite biochar, 6 parts of functional additives, 5 parts of film-forming agents, 4 parts of ethylene glycol, 7 parts of potassium benzoate, 6 parts of sorbic acid and 50 parts of water.

[0074] The preparation process of composite biochar is as follows:

[0075] The first substrate was placed in deionized water at a solid-liquid ratio of 0.12 g / mL and ultrasonically treated for 30 minutes, and a second substrate of 400% of the mass of the first substrate was added thereto, and the mixture was oscillated at a constant temperature of 35° C. and 200 r / min for 40 minutes;

[0076] After the constant temperature oscillation is completed, the mixture is filtered and then dried at 100° C. to a constant weight to obtain composite biochar.

[0077] Furthermore, the preparation process of the first substrate is as follows:

[0078] The rice straw was crushed into 60 meshes, and dried in air at 100°C to constant weight to obtain straw powder;

[0079] The straw powder was placed in a sodium hydroxide solution with a mass concentration of 25% at a solid-liquid ratio of 0.8 g / mL, and treated at 120° C. for 120 minutes. After filtration, a sulfuric acid solution with a mass concentration of 8% was added to the obtained filtrate at 65° C. until the pH value reached 2.3. After filtration, the obtained filter cake was centrifuged at 5600 r / min for 20 minutes. The centrifuged product was washed 4 times with a sulfuric acid solution with a mass concentration of 8%, and then freeze-dried to obtain a first substrate.

[0080] In addition, the preparation process of the second substrate is as follows:

[0081] The composite powder was placed in a sodium hydroxide solution with a mass concentration of 35% at a solid-liquid ratio of 0.2 g / mL, treated at 100 r / min for 10 min, and then left to stand for 7 h;

[0082] The dried product was placed in a tube furnace, heated from room temperature to 620°C at a heating rate of 6°C / min in a nitrogen atmosphere, and kept warm for 200 min.

[0083] After the heat preservation is completed, the product is ground and washed 6 times with deionized water. Finally, it is dried at a temperature of 100° C. to a constant weight to obtain a second substrate.

[0084] Furthermore, the composite powder is prepared by mixing Lantana camara stem powder and Water hyacinth leaf powder in a mass ratio of 1:0.4.

[0085] The functional additive is prepared by mixing fertilizer solution and violet pigment in a mass ratio of 1:0.12.

[0086] Furthermore, the fertilizer solution is prepared by mixing rubidium sulfate and water at a solid-liquid ratio of 0.05 g / mL.

[0087] The film-forming agent used is 853 film-forming agent.

[0088] In addition, this embodiment also provides a method for preparing the above-mentioned biochar seed coating agent, comprising the following steps:

[0089] Step 1, accurately weigh the composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water, and put the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water into a mixing device for mixing and stirring, and ball mill after mixing evenly;

[0090] Step 2: After the ball milling is completed, add the composite biochar and functional additives, and continue to stir and mix;

[0091] Step 3: After the mixing is completed, the material is discharged, and then it is inspected and packaged in sequence to finally obtain the finished product of the biomass charcoal seed coating agent.

[0092] Comparative Example 1: The difference from Example 1 is that in this example, an equal amount of biochar (wheat straw is collected, dried, crushed, and then carbonized at a constant temperature of 450°C in a tubular furnace with nitrogen for 4 hours; the carbonized solid is sieved through a 100-mesh sieve to obtain biochar) is used instead of the composite biochar.

[0093] Comparative Example 2: The difference from Example 1 is that this example does not contain a functional additive.

[0094] Comparative Example 3: The difference from Example 1 is that the functional additive of this example does not contain violet pigment.

[0095] Performance test: The biomass charcoal seed coating agent samples provided in Examples 1 to 3 and Comparative Examples 1 to 3 are marked as Examples 1 to 3 and Comparative Examples 1 to 3, respectively; and the relevant properties of the biomass charcoal seed coating agent provided in Examples 1 to 3 and Comparative Examples 1 to 3 are tested as follows:

[0096] 1. Growth test: The test method adopts random partition design, with each plot area of ​​50m 2 , the spacing between rows and plants was 0.4m×0.6m, and one corn seed was sown in each hole. Each plot was isolated from each other, and the field management was carried out in the local conventional way. The number of seedlings was investigated 15 days after sowing, the number of seedlings was recorded, and the emergence rate was calculated. Samples were taken at 5 points in each plot, with 5 plants at each point. After washing, the plant height, root length and number of fibrous roots were measured.

[0097] 2. Disease resistance test: The test method is to investigate the number of corn stalk rot diseased plants in the plot in a generated test manner. The typical field symptoms of corn stalk rot are typical wilt symptoms on leaves and softening of the stem base. Among them, the prevention effect (%) on corn stalk rot = [(number of control diseased plants - number of treated diseased plants) / number of control diseased plants] × 100.

[0098] The obtained test data are recorded in Tables 1 to 3 below:

[0099] Table 1 Test results of germination rate of each group

[0100] Group Seedling rate (%) Example 1 Group 95.6 Example 2 Group 95.4 Example 3 Group 95.2 Comparison group 1 89.5 Comparison of 2 groups 91.8 Comparison of 3 groups 94.2

[0101] Table 2 Test results of growth data of each group

[0102] Group Plant height (cm) Root length (cm) Root number (cm) Example 1 Group 26.5 22.3 6.3 Example 2 Group 26.4 22.4 6.5 Example 3 Group 26.4 22.2 6.4 Comparison group 1 21.5 17.4 5.4 Example 2 Group 22.2 16.8 5.3 Example 3 Group 26.1 21.8 6.2

[0103] Table 3 Disease prevention rate test results of each group

[0104]

[0105]

[0106] By comparing and analyzing the relevant data in Tables 1 to 3, it can be seen that the biochar seed coating agent prepared by the present invention not only has a good function of improving the emergence rate of crops, but also has a function of promoting the growth of crops, and also has an excellent pest control effect, effectively ensuring its quality. This shows that the biochar seed coating agent and its preparation method provided by the present invention have a broader market prospect and are more suitable for promotion.

[0107] In the present invention, composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water are used as raw materials, and the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water are put into a mixing device for mixing and stirring, and ball milling is performed after being evenly mixed, and then composite biochar and functional additives are added thereto, and stirring and mixing is continued. After the mixing is completed, the material is discharged, and then the inspection and metering packaging process are carried out in sequence to finally obtain the finished product of the biochar seed coating agent. The biochar seed coating agent prepared by the present invention not only has a good function of improving the emergence rate of crops, but also has a function of promoting the growth of crops, and also has an excellent effect of preventing and controlling diseases and insect pests.

[0108] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0109] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A biochar seed coating agent, characterized in that: The invention is composed of the following raw materials in parts by weight: 20 to 30 parts of composite biomass carbon, 3 to 6 parts of functional additives, 3 to 5 parts of film-forming agents, 2 to 4 parts of ethylene glycol, 4 to 7 parts of potassium benzoate, 2 to 6 parts of sorbic acid and 30 to 50 parts of water.

2. A biochar seed coating agent according to claim 1, characterized in that: The preparation process of the composite biochar is as follows: The first substrate is placed in deionized water for ultrasonic treatment at a solid-liquid ratio of 0.02 to 0.12 g / mL for 20 to 30 minutes, and a second substrate of 380 to 400% of the mass of the first substrate is added thereto, and the mixture is oscillated at a constant temperature of 30 to 35° C. and 200 r / min for 30 to 40 minutes; After the constant temperature oscillation is completed, the mixture is filtered and then dried at a temperature of 70 to 100° C. to a constant weight to obtain composite biochar.

3. A biochar seed coating agent according to claim 2, characterized in that: The preparation process of the first substrate is as follows: The rice straw is crushed into 40-60 meshes, and dried in air at 100°C to a constant weight to obtain straw powder; The straw powder is placed in a sodium hydroxide solution with a mass concentration of 22 to 25% at a solid-liquid ratio of 0.2 to 0.8 g / mL, and treated at 110 to 120° C. for 100 to 120 minutes. After suction filtration, a sulfuric acid solution with a mass concentration of 8% is added to the obtained filtrate at 62 to 65° C. until the pH value reaches 2.1 to 2.

3. After suction filtration, the obtained filter cake is centrifuged at 5200 to 5600 r / min for 10 to 20 minutes, and the centrifugal product is washed 2 to 4 times with a sulfuric acid solution with a mass concentration of 8%, and then freeze-dried to obtain a first substrate.

4. A biochar seed coating agent according to claim 2, characterized in that: The preparation process of the second substrate is as follows: The composite powder is placed in a sodium hydroxide solution with a mass concentration of 32-35% at a solid-liquid ratio of 0.08-0.2 g / mL, treated at 80-100 r / min for 5-10 minutes, and then left to stand for 6-7 hours; The dried product was placed in a tube furnace, heated from room temperature to 610-620°C at a heating rate of 6°C / min in a nitrogen atmosphere, and kept warm for 180-200 min; After the heat preservation is completed, the ground product is ground and washed with deionized water for 2 to 6 times. Finally, it is dried at a temperature of 70 to 100° C. to a constant weight to obtain a second substrate.

5. A biochar seed coating agent according to claim 4, characterized in that: The composite powder is prepared by mixing lantana stem powder and water hyacinth leaf powder in a mass ratio of 1:0.2-0.

4.

6. The biochar seed coating agent according to claim 1, characterized in that: The functional additive is prepared by mixing fertilizer liquid and violet pigment in a mass ratio of 1:0.08-0.

12.

7. A biochar seed coating agent according to claim 6, characterized in that: The fertilizer solution is prepared by mixing rubidium sulfate and water at a solid-liquid ratio of 0.01-0.05 g / mL.

8. The biochar seed coating agent according to claim 1, characterized in that: The film-forming agent is selected from any one of 805 film-forming agent, 851 film-forming agent and 853 film-forming agent.

9. The method for preparing a biochar seed coating agent according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, accurately weigh the composite biochar, functional additives, film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water, and put the film-forming agent, ethylene glycol, potassium benzoate, sorbic acid and water into a mixing device for mixing and stirring, and ball mill after mixing evenly; Step 2: After the ball milling is completed, add the composite biochar and functional additives, and continue to stir and mix; Step 3: After the mixing is completed, the material is discharged, and then it is inspected and packaged in sequence to finally obtain the finished product of the biomass charcoal seed coating agent.

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