Biochar-based compound fertilizer for improving soil acidification and preparation method thereof

Abstract

The invention relates to a charcoal-based compound fertilizer for improving soil acidification and a preparation method thereof, and belongs to the technical field of agriculture. Magnesium element, plant source biomass and animal source biomass are jointly pyrolyzed to prepare magnesium-containing biochar, chitin is introduced, and modified biochar rich in multiple nutrient elements is prepared. The biochar not only has the fertilizer efficiency of traditional organic fertilizers, but also can remarkably increase the pH value of soil, and meanwhile, the soil structure improvement capability and the water and fertilizer retention capability of the biochar are enhanced. Besides, the modified biochar is compounded with humic acid, amino acid, sodium carboxymethyl cellulose, attapulgite, corn starch and the like to prepare the biochar-based compound fertilizer, and the fertilizer can significantly improve soil acidification, improve soil fertility, promote plant growth and development and improve crop yield and quality; and the fertilizer also has the advantages of long-acting slow release and enhancement of plant stress resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture and relates to a biochar-based compound fertilizer for improving soil acidification and a preparation method thereof. Background Art

[0002] With the continuous progress of agricultural production, the problem of soil acidification has become increasingly serious, affecting the normal growth and yield of crops. Traditional fertilizers, while providing nutrients, often aggravate soil acidification, which is not conducive to the sustainable development of agriculture. As a new type of soil improvement material, biochar has shown great potential in improving soil physical and chemical properties and increasing soil fertility due to its rich pore structure and strong adsorption. However, single biochar is difficult to meet the comprehensive nutritional needs of crops, so it is of great significance to develop a biochar-based compound fertilizer that combines improving soil acidification with providing nutrients. Summary of the invention

[0003] The object of the present invention is to provide a biochar-based compound fertilizer for improving soil acidification and a preparation method thereof, which has the characteristics of improving soil acidification, providing fertility and retaining water and fertilizer.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A biochar-based compound fertilizer for improving soil acidification, wherein the formula of the biochar-based compound fertilizer is as follows: by weight percentage, 75-85% of modified biochar, 5-15% of humic acid, 5-10% of amino acid, 3-5% of bonding granulating agent, and 2-3% of sodium carboxymethyl cellulose.

[0006] The modified biochar preparation method is as follows:

[0007] S1-1: Mix crop waste and animal manure in a mass ratio of 3:1, place in a ventilated and cool place to dry for 24 hours, use a crusher to crush the crop waste and animal manure, and filter with a 2 mm sieve to obtain mixed biomass;

[0008] S1-2: The mixed biomass and magnesium chloride solution were mixed in a mass ratio of 1:5, ultrasonicated at 60°C for 1 h, filtered and dried in a vacuum oven at 60°C for 6 h, placed in a muffle furnace and pyrolyzed in a nitrogen atmosphere at a heating rate of 5°C / min, a maximum pyrolysis temperature of 350-450°C, and a pyrolysis time of 1.5 h to obtain magnesium-containing biochar;

[0009] S1-3: chitosan and 3M phosphoric acid solution were mixed in a mass ratio of 1:8, the mixture of chitosan and phosphoric acid was frozen with liquid nitrogen, and then placed in a 40°C water bath for stirring and thawing to obtain a mixed solution A, magnesium-containing biochar was added to the mixed solution A, and ultrasonic stirring was performed for 30 minutes to obtain a mixed solution B;

[0010] S1-4: Add 3M potassium hydroxide solution dropwise to the mixed solution B, stir for 6 hours, filter and wash the precipitate with deionized water, place in a vacuum oven at 60° C. and dry for 12 hours, and pass through a 200-mesh sieve to obtain the modified biochar.

[0011] Furthermore, the bonding granulating agent is a mixture of corn starch and attapulgite, wherein the mass ratio of corn starch to attapulgite is 1:2.

[0012] Furthermore, the amino acid is L-arginine.

[0013] Furthermore, the crop waste in S1-1 is one or more of rice straw, corn straw, and rice husk.

[0014] Furthermore, the animal manure in S1-1 is one or more of chicken manure, duck manure, and pig manure.

[0015] Furthermore, the concentration of the magnesium chloride solution in S1-2 is 1M.

[0016] Furthermore, the mass ratio of the magnesium-containing biochar to the mixed solution A in S1-3 is 1:5.

[0017] Furthermore, the dripping rate of the potassium hydroxide solution in S1-4 is 2 mL / min.

[0018] A method for preparing a biochar-based compound fertilizer for improving soil acidification, the preparation process of the biochar-based compound fertilizer is as follows:

[0019] S9-1: Mixing modified biochar, humic acid, amino acid, a binding granulating agent and sodium carboxymethyl cellulose according to a formula to obtain a mixed raw material;

[0020] S9-2: placing the mixed raw materials in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain fertilizer granules;

[0021] S9-3: placing the fertilizer particles in an electric blast drying oven and drying them at 120° C. for 2 hours, screening out qualified fertilizer particles with a particle size of 5 mm through a screening device after drying, and packaging the screened fertilizer particles to obtain the biochar-based composite fertilizer.

[0022] Furthermore, the mass ratio of deionized water to mixed raw materials in S9-2 is 1:10.

[0023] Crop waste and animal manure are selected together as biochar precursors, wherein crop waste provides a rich carbon source, while animal manure provides rich nutrients such as nitrogen and phosphorus. After the two are mixed and carbonized, the resulting biochar not only retains the carbon adsorption and water retention properties, but is also rich in nutrients required for plant growth; the fiber structure in crop waste helps to increase the air permeability during the carbonization process, while the high moisture and organic matter in animal manure help the carbonization reaction. After the two are mixed, the carbonization efficiency can be improved and energy consumption can be reduced; the carbonized mixed biochar not only has the fertilizer effect of traditional organic fertilizers, but also has the functions of improving soil structure and improving soil water and fertilizer retention capacity, thereby improving the yield and quality of crops.

[0024] Magnesium chloride is mixed with the mixed biomass before pyrolysis. Magnesium ions are partially converted into magnesium oxide and other forms of magnesium-containing compounds during the pyrolysis process, which helps to neutralize hydrogen ions in the soil and reduce the acidity of the soil. Magnesium is one of the nutrients necessary for plant growth and plays an important role in plant photosynthesis, enzyme activity and protein synthesis. The addition of magnesium chloride makes the prepared biochar rich in magnesium, which can be gradually absorbed and utilized by plants in the soil, thereby improving soil fertility.

[0025] Chitosan is extracted from shrimp and crab shells, with a wide range of sources and a pollution-free production process. Chitosan is a natural alkaline polysaccharide. Introducing chitosan into biochar helps to increase the pH of acidic soil. At the same time, chitosan can not only stimulate the germination process of seeds through its biological activity, but also promote the growth and overall development of plant roots, thereby increasing crop yield and quality. In addition, with its excellent moisture absorption and moisture retention capabilities, chitosan can also effectively improve the interaction between soil particles and optimize the soil aggregation structure. This mechanism of action helps to reduce the loss and leaching of key nutrients such as nitrogen and phosphorus caused by rain erosion or irrigation.

[0026] The introduction of phosphate not only helps the adsorption of chitin and biochar, but also combines with aluminum ions in the soil to form insoluble aluminum phosphate precipitates, reducing the acidity of the soil and reducing the toxic effects of aluminum ions; in addition, phosphorus is one of the essential nutrients for plant growth and plays an important role in the growth and development of plants. The hydroxide ions in potassium hydroxide neutralize the hydrogen ions in phosphoric acid, further increasing the alkalinity of biochar, and at the same time, potassium elements necessary for plant growth can be introduced into fertilizers to promote plant growth and improve the soil microenvironment.

[0027] In acidic soil, humic acid can neutralize part of acidic substances and release alkaline groups. Multiple functional groups in humic acid molecules can form stable complexes with aluminum ions. Humic acid is also an important carbon source and energy substance for soil microorganisms, which can promote the reproduction and activity of soil microorganisms and promote the recovery and improvement of soil fertility. L-arginine is beneficial to promote plant growth and development, and improve the resistance of crops to adverse environments. Sodium carboxymethyl cellulose, as a highly absorbent polymer, has the advantages of water retention, slow fertilizer application, improving soil structure stability and low cost. The addition of attapulgite and corn starch is beneficial to promote fertilizer bonding and granulation. In addition, attapulgite also has the effect of slow-release fertilizer, and corn starch helps stimulate the activity of microorganisms in the soil and increase soil vitality.

[0028] Beneficial effects of the present invention:

[0029] (1) The present invention prepares modified biochar, pyrolyzes magnesium, plant-derived and animal-derived biomass together, and introduces chitin and phosphate into the biochar. Then, potassium hydroxide is used to neutralize the phosphate and increase the alkalinity of the modified biochar. The modified biochar is beneficial to significantly increase the pH value of the soil, improve the soil structure, enhance the water and fertilizer retention capacity of the soil, and promote the growth and development of plants, thereby increasing the yield and quality of crops.

[0030] (2) The modified biochar, humic acid, amino acids, starch, attapulgite and sodium carboxymethyl cellulose are used together to prepare a biochar-based compound fertilizer, which is beneficial to further improve the fertilizer efficiency, promote the growth and development of plants and enhance their stress resistance, while promoting the uniform and slow release of fertilizer fertility and promoting the long-term effectiveness of the compound fertilizer. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0032]

[0033] Example 1

[0034] The formula 1 of biochar-based compound fertilizer is as follows: by weight percentage, modified biochar 80%, humic acid 10%, L-arginine 5%, attapulgite 2%, corn starch 1%, sodium carboxymethyl cellulose 2%,

[0035] The modified biochar preparation method is as follows:

[0036] S1-1: corn stalks and chicken manure were mixed in a mass ratio of 3:1, placed in a ventilated and cool place to dry for 24 hours, crushed the corn stalks and chicken manure using a crusher, and filtered with a 2 mm sieve to obtain mixed biomass;

[0037] S1-2: The mixed biomass was mixed with 1M magnesium chloride solution in a mass ratio of 1:5, ultrasonicated at 60°C for 1 h, filtered and dried in a vacuum oven at 60°C for 6 h, placed in a muffle furnace and pyrolyzed in a nitrogen atmosphere at a heating rate of 5°C / min, a maximum pyrolysis temperature of 350°C, and a pyrolysis time of 1.5 h to obtain magnesium-containing biochar;

[0038] S1-3: chitosan and 3M phosphoric acid solution were mixed in a mass ratio of 1:8, the mixture of chitosan and phosphoric acid was frozen with liquid nitrogen, and then placed in a 40°C water bath for stirring and thawing to obtain a mixed solution A, magnesium-containing biochar was added to the mixed solution A, wherein the mass ratio of magnesium-containing biochar to mixed solution A was 1:5, and ultrasonic stirring was performed for 30 minutes to obtain a mixed solution B;

[0039] S1-4: Add 3M potassium hydroxide solution dropwise to the mixed solution B, control the dropping speed to 2mL / min, the volume ratio of potassium hydroxide solution to mixed solution B is 3:1, stir for 6h, filter and wash the precipitate with deionized water, place it in a vacuum oven at 60°C and dry it for 12h, and pass it through a 200-mesh sieve to obtain the modified biochar.

[0040] A method for preparing a biochar-based compound fertilizer for improving soil acidification, the preparation process of the biochar-based compound fertilizer is as follows:

[0041] S9-1: According to formula 1, modified biochar, humic acid, L-arginine, attapulgite, corn starch and sodium carboxymethyl cellulose are mixed to obtain a mixed raw material;

[0042] S9-2: placing the mixed raw materials in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process, the mass ratio of deionized water to the mixed raw materials being 1:10, to obtain fertilizer granules;

[0043] S9-3: placing the fertilizer particles in an electric blast drying oven and drying them at 120° C. for 2 hours, screening out qualified fertilizer particles with a particle size of 5 mm through a screening device after drying, and packaging the screened fertilizer particles to obtain the biochar-based composite fertilizer.

[0044] Example 2

[0045] The formula 2 of biochar-based compound fertilizer is as follows: by weight percentage, modified biochar 75%, humic acid 13%, L-arginine 7%, attapulgite 2%, corn starch 1%, sodium carboxymethyl cellulose 2%,

[0046] The modified biochar preparation method is as follows:

[0047] S1-1: Mix rice straw and duck manure in a mass ratio of 3:1, place in a ventilated and cool place to dry for 24 hours, use a crusher to crush corn straw and chicken manure, and filter with a 2 mm sieve to obtain mixed biomass;

[0048] S1-2: The mixed biomass was mixed with 1M magnesium chloride solution in a mass ratio of 1:5, ultrasonicated at 60°C for 1 h, filtered and dried in a vacuum oven at 60°C for 6 h, placed in a muffle furnace and pyrolyzed in a nitrogen atmosphere at a heating rate of 5°C / min, a maximum pyrolysis temperature of 400°C, and a pyrolysis time of 1.5 h to obtain magnesium-containing biochar;

[0049] S1-3: chitosan and 3M phosphoric acid solution were mixed in a mass ratio of 1:8, the mixture of chitosan and phosphoric acid was frozen with liquid nitrogen, and then placed in a 40°C water bath for stirring and thawing to obtain a mixed solution A, magnesium-containing biochar was added to the mixed solution A, wherein the mass ratio of magnesium-containing biochar to mixed solution A was 1:5, and ultrasonic stirring was performed for 30 minutes to obtain a mixed solution B;

[0050] S1-4: Add 3M potassium hydroxide solution dropwise to the mixed solution B, control the dropping speed to 2mL / min, the volume ratio of potassium hydroxide solution to mixed solution B is 3:1, stir for 6h, filter and wash the precipitate with deionized water, place it in a vacuum oven at 60°C and dry it for 12h, and pass it through a 200-mesh sieve to obtain the modified biochar.

[0051] A method for preparing a biochar-based compound fertilizer for improving soil acidification, the preparation process of the biochar-based compound fertilizer is as follows:

[0052] S9-1: According to formula 2, modified biochar, humic acid, L-arginine, attapulgite, corn starch and sodium carboxymethyl cellulose are mixed to obtain a mixed raw material;

[0053] S9-2: placing the mixed raw materials in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process, the mass ratio of deionized water to the mixed raw materials being 1:10, to obtain fertilizer granules;

[0054] S9-3: placing the fertilizer particles in an electric blast drying oven and drying them at 120° C. for 2 hours, screening out qualified fertilizer particles with a particle size of 5 mm through a screening device after drying, and packaging the screened fertilizer particles to obtain the biochar-based composite fertilizer.

[0055] Example 3

[0056] The formula 3 of biochar-based compound fertilizer is as follows: by weight percentage, modified biochar 85%, humic acid 5%, L-arginine 5%, attapulgite 2%, corn starch 1%, sodium carboxymethyl cellulose 2%,

[0057] The modified biochar preparation method is as follows:

[0058] S1-1: Mix rice husk and pig manure in a mass ratio of 3:1, place in a ventilated and cool place to dry for 24 hours, use a crusher to crush corn stalks and chicken manure, and filter with a 2 mm sieve to obtain mixed biomass;

[0059] S1-2: The mixed biomass was mixed with 1M magnesium chloride solution in a mass ratio of 1:5, ultrasonicated at 60°C for 1 h, filtered and dried in a vacuum oven at 60°C for 6 h, placed in a muffle furnace and pyrolyzed in a nitrogen atmosphere at a heating rate of 5°C / min, a maximum pyrolysis temperature of 450°C, and a pyrolysis time of 1.5 h to obtain magnesium-containing biochar;

[0060] S1-3: chitosan and 3M phosphoric acid solution were mixed in a mass ratio of 1:8, the mixture of chitosan and phosphoric acid was frozen with liquid nitrogen, and then placed in a 40°C water bath for stirring and thawing to obtain a mixed solution A, magnesium-containing biochar was added to the mixed solution A, wherein the mass ratio of magnesium-containing biochar to mixed solution A was 1:5, and ultrasonic stirring was performed for 30 minutes to obtain a mixed solution B;

[0061] S1-4: Add 3M potassium hydroxide solution dropwise to the mixed solution B, control the dropping speed to 2mL / min, the volume ratio of potassium hydroxide solution to mixed solution B is 3:1, stir for 6h, filter and wash the precipitate with deionized water, place it in a vacuum oven at 60°C and dry it for 12h, and pass it through a 200-mesh sieve to obtain the modified biochar.

[0062] A method for preparing a biochar-based compound fertilizer for improving soil acidification, the preparation process of the biochar-based compound fertilizer is as follows:

[0063] S9-1: According to formula 3, modified biochar, humic acid, L-arginine, attapulgite, corn starch and sodium carboxymethyl cellulose are mixed to obtain a mixed raw material;

[0064] S9-2: placing the mixed raw materials in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process, the mass ratio of deionized water to the mixed raw materials being 1:10, to obtain fertilizer granules;

[0065] S9-3: placing the fertilizer particles in an electric blast drying oven and drying them at 120° C. for 2 hours, screening out qualified fertilizer particles with a particle size of 5 mm through a screening device after drying, and packaging the screened fertilizer particles to obtain the biochar-based composite fertilizer.

[0066] Comparative Example 1

[0067] No magnesium chloride solution was added to the modified biochar, and the remaining steps were consistent with Example 1.

[0068] Comparative Example 2

[0069] No chitosan was added to the modified biochar, and the remaining steps were consistent with those in Example 1.

[0070] Comparative Example 3

[0071] The modified biochar in Example 1 is directly used as fertilizer without preparing biochar-based composite fertilizer.

[0072] Take a flowerpot with a diameter of 15 cm and a height of 25 cm, add 2 kg of test soil with a dry weight into the flowerpot, and add the embodiments and comparative examples to the soil at 1.5% of the dry weight of the test soil, and culture at 37 ° C for 60 days, using the test soil without fertilizer as a blank. During the culture period, deionized water was added in time according to the dryness and wetness of the soil and the change in quality to keep the soil moisture content at 70% of the field water holding capacity. Soil samples from all pots were collected at 30 days and 60 days of culture, naturally air-dried, ground through a 2 mm sieve for pH determination. The pH value of the soil was determined in accordance with HJ 962-2018 "Potential Method for Determination of Soil pH Value", where the mass ratio of soil to water was 10:25.

[0073] The test soil was collected from acidified yellow-red soil in Chizhou, Anhui Province, and the initial soil pH was 5.66.

[0074] The experimental results are summarized in the following table:

[0075]

[0076] It can be seen from the data of the embodiments and comparative examples that the use of magnesium ions and chitosan to synergistically modify biochar significantly increases the soil pH value and improves the soil acidification problem; the composite fertilizer prepared based on modified biochar and the addition of humic acid, L-arginine, attapulgite, corn starch, sodium carboxymethyl cellulose and other raw materials has a long-lasting effect and has a more prominent effect on improving acidic soils.

[0077] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A biochar-based compound fertilizer for improving soil acidification, characterized in that: The formula of the biochar-based composite fertilizer is as follows: by weight percentage, modified biochar 75-85%, humic acid 5-15%, amino acid 5-10%, bonding granulating agent 3-5%, sodium carboxymethyl cellulose 2-3%, The modified biochar preparation method is as follows: S1-1: Mix crop waste and animal manure in a mass ratio of 3:1, place in a ventilated and cool place to dry for 24 hours, use a crusher to crush the crop waste and animal manure, and filter with a 2 mm sieve to obtain mixed biomass; S1-2: The mixed biomass and magnesium chloride solution were mixed in a mass ratio of 1:5, ultrasonicated at 60°C for 1 h, filtered and dried in a vacuum oven at 60°C for 6 h, placed in a muffle furnace and pyrolyzed in a nitrogen atmosphere at a heating rate of 5°C / min, a maximum pyrolysis temperature of 350-450°C, and a pyrolysis time of 1.5 h to obtain magnesium-containing biochar; S1-3: chitosan and 3M phosphoric acid solution were mixed in a mass ratio of 1:8, the mixture of chitosan and phosphoric acid was frozen with liquid nitrogen, and then placed in a 40°C water bath for stirring and thawing to obtain a mixed solution A, magnesium-containing biochar was added to the mixed solution A, and ultrasonic stirring was performed for 30 minutes to obtain a mixed solution B; S1-4: Add 3M potassium hydroxide solution dropwise to the mixed solution B, stir for 6 hours, filter and wash the precipitate with deionized water, place in a vacuum oven at 60° C. and dry for 12 hours, and pass through a 200-mesh sieve to obtain the modified biochar.

2. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The bonding granulating agent is a mixture of corn starch and attapulgite, wherein the mass ratio of corn starch to attapulgite is 1:

2.

3. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The amino acid is L-arginine.

4. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The crop waste in S1-1 is one or more of rice straw, corn straw, and rice husk.

5. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The animal manure in S1-1 is one or more of chicken manure, duck manure, and pig manure.

6. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The concentration of the magnesium chloride solution in S1-2 is 1M.

7. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The mass ratio of the magnesium-containing biochar to the mixed solution A in S1-3 is 1:

5.

8. The biochar-based compound fertilizer for improving soil acidification according to claim 1, characterized in that: The dripping rate of the potassium hydroxide solution in S1-4 is 2 mL / min.

9. A method for preparing a biochar-based compound fertilizer for improving soil acidification according to any one of claims 1 to 8, characterized in that: The preparation method of the biochar-based composite fertilizer is as follows: S9-1: Mixing modified biochar, humic acid, amino acid, a binding granulating agent and sodium carboxymethyl cellulose according to a formula to obtain a mixed raw material; S9-2: placing the mixed raw materials in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain fertilizer granules; S9-3: placing the fertilizer particles in an electric blast drying oven and drying them at 120° C. for 2 hours, screening out qualified fertilizer particles with a particle size of 5 mm through a screening device after drying, and packaging the screened fertilizer particles to obtain the biochar-based composite fertilizer.

10. The method for preparing a biochar-based compound fertilizer for improving soil acidification according to claim 9, characterized in that: The mass ratio of deionized water to mixed raw materials in S9-2 is 1:10.

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