Wormcast biochar-based soil conditioner as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of soil improvement, and discloses a wormcast biochar-based soil conditioner as well as a preparation method and application thereof. The soil conditioner is prepared from the following raw materials: modified charcoal, wormcast, a seaweed fertilizer, a microbial agent, vermiculite, humic acid, urea and coal gangue. The modified biochar and the wormcast are used as main components, the modified biochar is loaded with potassium and phosphorus, and potassium and phosphorus elements can be slowly released and provided; on one hand, plasma modification can generate oxygen-containing groups and increase active sites, so that heavy metals are complexed, and the removal capacity of the heavy metals is improved; on the other hand, holes in the surface of the biochar can be increased, the specific surface area is increased, the adsorbability is improved, and the biochar can serve as a carrier of components such as microorganisms, wormcast and urea, so that nutrient substances are slowly released in soil. Wormcast contains some bacteria, fungi and the like, promotes plant growth and serves as organic fertilizer together with seaweed fertilizer and humic acid, and the content of organic matter and mineral matter in soil is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to an earthworm castings biochar-based soil conditioner and a preparation method and application thereof. Background Art

[0002] With the development of specialty agriculture, soil problems have an increasingly serious impact on the specialty agriculture industry. When the salt content in the soil is too high, the osmotic pressure of the solution in the soil is higher than the osmotic pressure of the crop cell fluid, causing the roots of the crop cells to dehydrate, resulting in crop seedling burns, withering, drought and other problems, seriously affecting the normal growth of crops. At the same time, excessive alkaline salt content in the soil will also affect the absorption of nutrients by crops, causing nutritional disorders in crops.

[0003] Biochar is a black, fluffy, light carbon-rich solid material made by heating biomass (such as agricultural waste, wood or organic materials) to high temperature under anaerobic conditions through pyrolysis technology. It usually exists in the form of particles and is mainly composed of elements such as carbon, hydrogen, oxygen, and nitrogen. The carbon content is usually more than 70%. Based on the above properties of biochar, the use of biochar as a soil conditioner has been widely studied. For example, patent CN103788954A discloses the use of biochar and fermented chicken manure as soil conditioners, but it has the problem of single effect and large application amount.

[0004] Therefore, developing a biochar-based soil conditioner with good improvement effect is of great significance to the development of characteristic agriculture. Summary of the invention

[0005] The purpose of the present invention is to provide a vermicompost biochar-based soil conditioner and a preparation method and application thereof, so as to solve the problems of existing biochar-based soil conditioners, such as single effect, large application amount, slow effect generation, etc.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a vermicompost biochar-based soil conditioner, comprising the following raw materials in parts by weight:

[0008] 80-100 parts of modified biochar, 50-90 parts of earthworm castings, 20-50 parts of seaweed fertilizer, 5-20 parts of microbial agent, 1-10 parts of vermiculite, 10-30 parts of humic acid, 10-20 parts of urea, and 1-25 parts of coal gangue;

[0009] The modified biochar is obtained by subjecting biomass raw materials to modification with a modifier, pyrolysis, and plasma treatment in sequence; the modifier is potassium hydroxide and potassium phosphate.

[0010] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the particle size of the vermiculite is 100 to 800 μm; and the particle size of the coal gangue is 50 to 500 μm.

[0011] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the method for preparing the modified biochar comprises the following steps:

[0012] The biomass raw material is immersed in an aqueous solution of a modifier for modification; after the modification, it is pyrolyzed under a protective atmosphere; after the pyrolysis, it is plasma treated to obtain the modified biochar.

[0013] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the concentration of potassium hydroxide in the aqueous solution of the modifier is 0.1 to 10 mol / L; the concentration of potassium phosphate in the aqueous solution of the modifier is 0.1 to 5 mol / L.

[0014] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the immersion temperature is 30 to 50° C.; and the immersion time is 2 to 6 hours.

[0015] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the pyrolysis temperature is 500-700° C.; and the pyrolysis time is 1-3 h.

[0016] Preferably, in the above-mentioned earthworm castings biochar-based soil conditioner, the parameters of the plasma treatment are: power of 100-300 W, oxygen flow rate of 200-500 Pa·m 3 / s, time is 60~360s.

[0017] The present invention also provides a method for preparing a vermicompost biochar-based soil conditioner, comprising the following steps:

[0018] The modified biochar, earthworm castings, seaweed fertilizer, and humic acid are mixed, and then vermiculite, urea, and coal gangue are added, and finally microbial agents are added, and granulated in a granulator to obtain an earthworm castings biochar-based soil conditioner.

[0019] The present invention also provides an earthworm castings biochar-based soil conditioner or an earthworm castings biochar-based soil conditioner prepared by a method for preparing the earthworm castings biochar-based soil conditioner and use of the earthworm castings biochar-based soil conditioner in improving light to moderate saline-alkali land.

[0020] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention uses modified biochar and earthworm castings as the main components of the soil conditioner. The modified biochar is loaded with potassium and phosphorus, and can provide potassium and phosphorus elements in the soil in a slow release manner. On the one hand, plasma modification can produce oxygen-containing groups, increase active sites, thereby complexing heavy metals and improving the removal capacity of heavy metals. On the other hand, plasma treatment can also increase the pores on the surface of biochar, increase the specific surface area, and improve the adsorption. It can be used as a carrier of components such as microorganisms, earthworm castings, and urea to release nutrients in the soil. Earthworm castings contain some bacteria, fungi, etc., which promote plant growth. It can be used together with seaweed fertilizer and humic acid as organic fertilizer to increase the content of organic matter and minerals in the soil. Vermiculite can alleviate the rapid change of soil pH value. Coal gangue can provide a variety of trace elements, urea can provide nitrogen, and microbial agents can improve microbial populations and increase soil activity. The present invention can improve soil fertility, increase organic matter, adjust soil pH, remove heavy metals, and promote plant growth through the compounding effect of the above-mentioned multiple components. DETAILED DESCRIPTION

[0022] The present invention provides a vermicompost biochar-based soil conditioner, comprising the following raw materials in parts by weight:

[0023] 80-100 parts of modified biochar, 50-90 parts of earthworm castings, 20-50 parts of seaweed fertilizer, 5-20 parts of microbial agent, 1-10 parts of vermiculite, 10-30 parts of humic acid, 10-20 parts of urea, and 1-25 parts of coal gangue.

[0024] In the present invention, the mass fraction of the modified biochar is preferably 85 to 95 parts, more preferably 87 to 90 parts, and more preferably 90 parts.

[0025] In the present invention, the mass fraction of the earthworm castings is preferably 55 to 80 parts, more preferably 60 to 75 parts, and even more preferably 70 parts.

[0026] In the present invention, the mass fraction of the seaweed fertilizer is preferably 22 to 46 parts, more preferably 33 to 40 parts, and more preferably 35 parts.

[0027] In the present invention, the mass fraction of the microbial agent is preferably 8 to 17 parts, more preferably 12 to 16 parts, and even more preferably 15 parts.

[0028] In the present invention, the mass fraction of the vermiculite is preferably 2 to 8 parts, more preferably 3 to 6 parts, and even more preferably 4 parts.

[0029] In the present invention, the mass fraction of the humic acid is preferably 13 to 28 parts, more preferably 15 to 25 parts, and even more preferably 20 parts.

[0030] In the present invention, the mass fraction of the urea is preferably 11 to 18 parts, more preferably 13 to 16 parts, and even more preferably 14 parts.

[0031] In the present invention, the mass fraction of the coal gangue is preferably 6 to 20 parts, more preferably 10 to 15 parts, and even more preferably 13 parts.

[0032] In the present invention, the modified biochar is obtained by subjecting the biomass raw material to modification by a modifier, pyrolysis, and plasma treatment in sequence.

[0033] In the present invention, the modifier is preferably potassium hydroxide and potassium phosphate.

[0034] In the present invention, the method for preparing the modified biochar comprises the following steps:

[0035] The biomass raw material is immersed in an aqueous solution of a modifier for modification; after the modification, it is pyrolyzed under a protective atmosphere; after the pyrolysis, it is plasma treated to obtain the modified biochar.

[0036] In the present invention, the biomass raw material is preferably straw.

[0037] In the present invention, the biomass raw material is further crushed before use; the particle size of the crushed material is preferably 100 to 1000 μm, more preferably 100 to 600 μm, and more preferably 100 to 300 μm.

[0038] In the present invention, the concentration of potassium hydroxide in the aqueous solution of the modifier is preferably 0.1 to 10 mol / L, more preferably 0.5 to 8 mol / L, and more preferably 6 mol / L; the concentration of potassium phosphate in the aqueous solution of the modifier is preferably 0.1 to 5 mol / L, more preferably 1 to 4 mol / L, and more preferably 2 mol / L.

[0039] In the present invention, the usage ratio of the biomass raw material to the aqueous solution of the modifier is preferably 50-500 g:500-1000 mL, more preferably 100-400 g:600-1000 mL, and even more preferably 300 g:900 mL.

[0040] In the present invention, the immersion temperature is preferably 30-50°C, more preferably 35-45°C, and more preferably 40°C; the immersion time is preferably 2-6h, more preferably 3-6h, and more preferably 4h.

[0041] In the present invention, the modification further includes centrifugation and drying; the centrifugal speed is preferably 1000-5000rpm, more preferably 1500-4000rpm, more preferably 3000rpm; the centrifugal time is preferably 5-20min, more preferably 10-20min, more preferably 15min; the drying temperature is preferably 60-100°C, more preferably 65-90°C, more preferably 80°C; the drying time is preferably 4-8h, more preferably 5-8h, more preferably 6h.

[0042] In the present invention, the pyrolysis temperature is preferably 500-700°C, more preferably 550-650°C, and more preferably 600°C; the pyrolysis time is preferably 1-3h, and more preferably 2h.

[0043] In the present invention, the protective atmosphere is preferably argon or nitrogen, more preferably nitrogen.

[0044] In the present invention, the parameters of the plasma treatment are: the power is preferably 100-300 W, more preferably 120-280 W, and more preferably 250 W; the oxygen flow rate is preferably 200-500 Pa·m 3 / s, more preferably 250 to 400 Pa·m 3 / s, more preferably 300Pa·m 3 / s; the time is preferably 60 to 360 s, more preferably 90 to 240 s, and even more preferably 180 s.

[0045] In the present invention, the earthworm castings were purchased from Hebei Rundong Fertilizer Co., Ltd.

[0046] In the present invention, the seaweed fertilizer is purchased from Dongyi Yang (Jinan) New Materials Co., Ltd.

[0047] In the present invention, the microbial agent is preferably a mixture of Bacillus subtilis, actinomycetes, photosynthetic bacteria, yeast, and Bacillus cereus; the mass ratio of Bacillus subtilis, actinomycetes, photosynthetic bacteria, yeast, and Bacillus cereus is preferably 3-5:1-2:4-7:1-3:2-4, more preferably 3-4:1-2:5-7:1-2:2-3, and more preferably 3:1:7:1:2.

[0048] In the present invention, the particle size of the vermiculite is preferably 100 to 800 μm, more preferably 100 to 600 μm, and even more preferably 100 to 500 μm.

[0049] In the present invention, the particle size of the coal gangue is preferably 50 to 500 μm, more preferably 100 to 400 μm, and even more preferably 100 to 200 μm.

[0050] The present invention also provides a method for preparing a vermicompost biochar-based soil conditioner, comprising the following steps:

[0051] The modified biochar, earthworm castings, seaweed fertilizer, and humic acid are mixed, and then vermiculite, urea, and coal gangue are added, and finally microbial agents are added, and granulated in a granulator to obtain an earthworm castings biochar-based soil conditioner.

[0052] In the present invention, the granulation temperature is preferably 60 to 80°C, more preferably 65 to 75°C, and even more preferably 70°C.

[0053] The present invention also provides an earthworm castings biochar-based soil conditioner or an earthworm castings biochar-based soil conditioner prepared by a method for preparing the earthworm castings biochar-based soil conditioner and use of the earthworm castings biochar-based soil conditioner in improving light to moderate saline-alkali land.

[0054] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0055] Example 1

[0056] This embodiment provides a vermicompost biochar-based soil conditioner, comprising the following raw materials in parts by weight:

[0057] 95 parts of modified biochar, 80 parts of earthworm castings, 33 parts of seaweed fertilizer, 15 parts of microbial agent, 8 parts of vermiculite, 20 parts of humic acid, 12 parts of urea, and 10 parts of coal gangue.

[0058] The method for preparing modified biochar comprises the following steps:

[0059] The straw was first crushed into particles of 100-300 μm, and then immersed in an aqueous solution of a modifier at 50°C for 3 h for modification. The concentration of potassium hydroxide in the aqueous solution of the modifier was 6 mol / L, the concentration of potassium phosphate was 4 mol / L, and the dosage ratio of straw particles to the aqueous solution of the modifier was 300 g:600 mL. After the modification, the product was centrifuged at 4000 rpm for 20 min and dried at 80°C for 6 h. Then, it was pyrolyzed at 640°C for 2 h in a nitrogen atmosphere to obtain biochar. After the pyrolysis, the biochar was subjected to plasma treatment with the following parameters: power of 280 W, oxygen flow rate of 330 Pa·m 3 / s, the time is 180s, and modified biochar is obtained.

[0060] The microbial agent is a mixture of Bacillus subtilis, actinomycetes, photosynthetic bacteria, yeast and Bacillus cereus in a mass ratio of 4:1:5:1:2; the particle size of vermiculite is 100-500 μm; and the particle size of coal gangue is 100-200 μm.

[0061] The preparation method of the above-mentioned earthworm castings biochar-based soil conditioner comprises the following steps:

[0062] The modified biochar, earthworm castings, seaweed fertilizer and humic acid are mixed and stirred evenly, and then vermiculite, urea and coal gangue are added and mixed and stirred evenly, and finally microbial agents are added, and granulated at 70° C. in a granulator to obtain an earthworm castings biochar-based soil conditioner.

[0063] Example 2

[0064] This embodiment provides a vermicompost biochar-based soil conditioner, comprising the following raw materials in parts by weight:

[0065] 80 parts of modified biochar, 60 parts of earthworm castings, 20 parts of seaweed fertilizer, 20 parts of microbial agent, 6 parts of vermiculite, 13 parts of humic acid, 20 parts of urea, and 15 parts of coal gangue.

[0066] The method for preparing modified biochar comprises the following steps:

[0067] The straw was first crushed into particles of 100-300 μm, and then immersed in an aqueous solution of a modifier at 40°C for 5 h for modification. The concentration of potassium hydroxide in the aqueous solution of the modifier was 5 mol / L, the concentration of potassium phosphate was 2 mol / L, and the dosage ratio of straw particles to the aqueous solution of the modifier was 200 g:500 mL. After the modification, the product was centrifuged at 3000 rpm for 10 min and dried at 60°C for 4 h. Then, it was pyrolyzed at 550°C for 3 h in a nitrogen atmosphere to obtain biochar. After the pyrolysis, the biochar was subjected to plasma treatment with the following parameters: power of 180 W and oxygen flow rate of 400 Pa·m 3 / s, the time is 260s, and modified biochar is obtained.

[0068] The microbial agent is a mixture of Bacillus subtilis, actinomycetes, photosynthetic bacteria, yeast and Bacillus cereus in a mass ratio of 3:2:5:5:3; the particle size of vermiculite is 100-500 μm; and the particle size of coal gangue is 100-200 μm.

[0069] The preparation method of the above-mentioned earthworm castings biochar-based soil conditioner comprises the following steps:

[0070] The modified biochar, earthworm castings, seaweed fertilizer and humic acid are mixed and stirred evenly, and then vermiculite, urea and coal gangue are added and mixed and stirred evenly, and finally microbial agents are added, and granulated at 60° C. in a granulator to obtain an earthworm castings biochar-based soil conditioner.

[0071] Example 3

[0072] This embodiment provides a vermicompost biochar-based soil conditioner, comprising the following raw materials in parts by weight:

[0073] 100 parts of modified biochar, 50 parts of earthworm castings, 40 parts of seaweed fertilizer, 5 parts of microbial agent, 2 parts of vermiculite, 15 parts of humic acid, 20 parts of urea, and 6 parts of coal gangue.

[0074] The method for preparing modified biochar comprises the following steps:

[0075] The straw was first crushed into particles of 100-300 μm, and then immersed in an aqueous solution of a modifier at 30°C for 6 h for modification. The concentration of potassium hydroxide in the aqueous solution of the modifier was 2 mol / L, the concentration of potassium phosphate was 5 mol / L, and the dosage ratio of the straw particles to the aqueous solution of the modifier was 500 g:1000 mL. After the modification, the product was centrifuged at 5000 rpm for 20 min and dried at 60°C for 6 h. Then, it was pyrolyzed at 700°C for 1 h in a nitrogen atmosphere to obtain biochar. After the pyrolysis, the biochar was subjected to plasma treatment with the following parameters: power of 120 W and oxygen flow rate of 250 Pa·m 3 / s, the time is 360s, and modified biochar is obtained.

[0076] The microbial agent is a mixture of Bacillus subtilis, actinomycetes, photosynthetic bacteria, yeast and Bacillus cereus in a mass ratio of 4:1:7:1:4; the particle size of vermiculite is 100-500 μm; and the particle size of coal gangue is 100-200 μm.

[0077] The preparation method of the above-mentioned earthworm castings biochar-based soil conditioner comprises the following steps:

[0078] The modified biochar, earthworm castings, seaweed fertilizer and humic acid are mixed and stirred evenly, and then vermiculite, urea and coal gangue are added and mixed and stirred evenly, and finally microbial agents are added, and granulated at 70° C. in a granulator to obtain an earthworm castings biochar-based soil conditioner.

[0079] Comparative Example 1

[0080] This comparative example provides a vermicompost biochar-based soil conditioner, see Example 1 for details, except that the modified biochar is replaced by biochar, and the preparation method of biochar includes the following steps: first crushing the straw into particles of 100 to 300 μm, pyrolyzing at 640° C. for 2 h under a nitrogen atmosphere to obtain biochar.

[0081] Comparative Example 2

[0082] This comparative example provides a vermicompost biochar-based soil conditioner, which is specifically described in Example 1, except that the modified biochar is not subjected to plasma treatment.

[0083] Comparative Example 3

[0084] This comparative example provides a biochar-based soil conditioner, which is specifically referred to in Example 1, except that it does not contain earthworm castings.

[0085] The soil conditioners of Examples 1 to 3 and Comparative Examples 1 to 3 were applied to slightly saline-alkali land (salinity of 1.8‰, pH of 7.84), respectively, with an application amount of 1% of the soil mass. The soil conditioner was mixed evenly with the soil, and the humidity was maintained at 60% for 10 days after watering. Then, soil physical and chemical properties were measured by sampling. The results are shown in Table 1.

[0086] Table 1 Physical and chemical properties of soil before and after application of soil conditioners

[0087]

[0088]

[0089] As shown in Table 1, after applying the soil conditioner of the present invention, the pH of saline-alkali soil decreased, and the contents of soil organic matter, total nitrogen, available phosphorus, and available potassium increased, indicating that the soil conditioner of the present invention can effectively improve soil structure, increase soil fertility, regulate soil acidity and alkalinity, and provide a good foundation for crop growth. In addition, plasma treatment of biochar can significantly reduce the content of heavy metals in the soil and reduce the risk of heavy metals being absorbed and enriched by crops.

[0090] The above is only 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A vermicompost biochar-based soil conditioner, characterized in that: Contains the following raw materials in parts by weight: 80-100 parts of modified biochar, 50-90 parts of earthworm castings, 20-50 parts of seaweed fertilizer, 5-20 parts of microbial agent, 1-10 parts of vermiculite, 10-30 parts of humic acid, 10-20 parts of urea, and 1-25 parts of coal gangue; The modified biochar is obtained by subjecting biomass raw materials to modification with a modifier, pyrolysis, and plasma treatment in sequence; the modifier is potassium hydroxide and potassium phosphate.

2. The earthworm castings biochar-based soil conditioner according to claim 1, characterized in that: The particle size of the vermiculite is 100-800 μm; the particle size of the coal gangue is 50-500 μm.

3. The earthworm castings biochar-based soil conditioner according to claim 1, characterized in that: The method for preparing the modified biochar comprises the following steps: The biomass raw material is immersed in an aqueous solution of a modifier for modification; after the modification, it is pyrolyzed under a protective atmosphere; after the pyrolysis, it is plasma treated to obtain the modified biochar.

4. The earthworm castings biochar-based soil conditioner according to claim 3, characterized in that: The concentration of potassium hydroxide in the aqueous solution of the modifier is 0.1-10 mol / L; the concentration of potassium phosphate in the aqueous solution of the modifier is 0.1-5 mol / L.

5. The earthworm castings biochar-based soil conditioner according to claim 3, characterized in that: The immersion temperature is 30-50° C. and the immersion time is 2-6 hours.

6. A vermicompost biochar-based soil conditioner according to claim 4 or 5, characterized in that: The pyrolysis temperature is 500-700° C.; the pyrolysis time is 1-3 hours.

7. The earthworm castings biochar-based soil conditioner according to claim 6, characterized in that: The parameters of the plasma treatment are: power of 100-300W, oxygen flow rate of 200-500Pa·m 3 / s, time is 60~360s.

8. The method for preparing a vermicompost biochar-based soil conditioner according to any one of claims 1 to 7, characterized in that: The following steps are involved: The modified biochar, earthworm castings, seaweed fertilizer, and humic acid are mixed, and then vermiculite, urea, and coal gangue are added, and finally microbial agents are added, and granulated in a granulator to obtain an earthworm castings biochar-based soil conditioner.

9. Use of the earthworm casting biochar-based soil conditioner according to any one of claims 1 to 7 or the earthworm casting biochar-based soil conditioner prepared by the preparation method of the earthworm casting biochar-based soil conditioner according to claim 8 in improving light to moderate saline-alkali land.

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