Humic acid-based soil alkali adjusting agent and preparation method thereof

Abstract

The invention discloses a humic acid-based soil alkalinity adjusting agent and a preparation method thereof, and belongs to the field of soil amendments, the humic acid-based soil alkalinity adjusting agent comprises the following raw materials by weight: 30-50 parts of a modified humic acid carrier; 8-15 parts of carbonate; 3-5 parts of a microbial agent; wherein the modified humic acid carrier is prepared from the following raw materials: acylating chlorinated nano humic acid, sulfamic acid and acidified chitosan in a mass ratio of 1: (0.1-0.4): (0.1-0.3). The density of acidic functional groups is improved by modifying nano humic acid through sulfamic acid, a three-dimensional network structure is constructed by the nano humic acid and acidified chitosan, and meanwhile, carbonate, a microbial agent and hydroxyapatite are compounded, so that high efficiency and durability of an alkali adjusting effect are realized. Compared with a traditional inorganic acid modifier, the modifier can prevent local pH sudden change from burning crop root systems, the three-dimensional network structure can delay carbonate release, the alkali adjusting effect is continuous, and the problems that a traditional modifier acts transiently, and soil is prone to being damaged are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of soil conditioners, and in particular to a humic acid-based soil alkali adjuster and its preparation method. Background Technology

[0002] Soil is the foundation of agricultural production, and the sufficiency of soil fertility directly affects crop growth, yield, and quality. When soil fertility is insufficient, crops are prone to problems such as hindered root development, yellowing leaves, and reduced stress resistance. In severe cases, it can lead to reduced yield or even crop failure. One of the important causes of soil fertility imbalance is abnormal fluctuations in soil pH.

[0003] When soil pH becomes unbalanced, especially when it becomes alkaline, it can trigger a series of serious problems. First, it drastically reduces the availability of various micronutrients in the soil, such as iron, manganese, zinc, and copper, causing them to precipitate and become difficult for crops to absorb, thus inducing nutrient deficiencies and significantly impacting crop growth and development. Second, an alkaline soil environment inhibits the activity of beneficial microorganisms, disrupts the balance of the soil ecosystem, and consequently affects the decomposition of organic matter and nutrient cycling. Furthermore, excessively high alkalinity promotes the dispersion of soil colloids, destroys soil aggregate structure, leading to soil compaction, reduced permeability, and impaired water penetration and root growth.

[0004] Currently, common measures to improve alkaline soils mainly include adding inorganic acids or acidic salts, such as applying sulfuric acid, ferrous sulfate, or sulfur. These substances directly lower the pH by neutralizing alkaline ions in the soil. However, this method is often too drastic; improper dosage can easily lead to sudden changes in local pH, burning crop roots, and its effects are short-lived and cannot be maintained long-term. More importantly, these substances only provide a single acid-regulating function and cannot improve soil structure; long-term use may even cause compaction. Another common method is to apply industrial byproducts such as phosphogypsum or desulfurized gypsum. The principle is to use calcium ions to replace sodium ions on soil colloids, and then wash away salts through irrigation. Although the cost is low, these byproducts have complex compositions and usually contain harmful impurities such as heavy metals and fluorides, posing a risk of soil and agricultural product pollution. Another method is to add organic materials, such as applying well-rotted farmyard manure, green manure, or returning straw to the field. These materials produce organic acids and carbon dioxide during decomposition, which can gently lower the pH and improve soil structure. However, this method is slow to adjust alkali, requires large amounts, and has a long time to take effect, making it difficult to meet the needs of improving moderately to severely alkalized soils.

[0005] Humic acid, a natural organic macromolecule, is widely found in natural resources such as lignite and peat. It is a core component of soil humus and a high-quality source of organic fertilizer. Humic acid itself is weakly acidic, which can directly neutralize soil alkalinity. Its large specific surface area and abundant functional groups, such as carboxyl and phenolic hydroxyl groups, endow it with ion exchange and buffering capabilities, stabilizing soil pH. More importantly, humic acid promotes the formation of soil aggregates, breaks up soil compaction, enhances soil water and fertilizer retention capacity, provides nutrients for microorganisms, and improves the soil ecological environment.

[0006] However, when natural humic acid is applied directly, its ability to regulate soil alkali is limited, and its dispersibility and stability in water are poor, affecting its soil-improving effect. Therefore, by modifying the humic acid molecules to increase its acidic functional group density and designing a slow-release structure, a highly efficient and multifunctional soil alkali regulator based on humic acid was developed. Summary of the Invention

[0007] The purpose of this invention is to provide a humic acid-based soil alkali conditioner to solve the problems of insufficient alkali-regulating ability and slow-release effect of natural humic acid in the prior art.

[0008] The present invention also aims to provide a method for preparing a humic acid-based soil alkali conditioner.

[0009] In a first aspect, the present invention provides a humic acid-based soil alkali conditioner, comprising the following raw materials in parts by weight: 30-50 parts of modified humic acid carrier; 8-15 parts carbonate; 3-5 parts of microbial inoculant; The raw materials for the modified humic acid carrier include acyl chloride nano-humic acid, aminosulfonic acid, and acidified chitosan in a mass ratio of 1:(0.1-0.4):(0.1-0.3).

[0010] Preferably, the carbonate includes calcium carbonate and / or magnesium carbonate.

[0011] Preferably, the microbial agent comprises Bacillus subtilis, Bacillus lateralis, and Bacillus megaterium in a mass ratio of (2-3):(1-2):(1-2).

[0012] By adopting the above technical solutions, the humic acid-based soil alkali adjuster of the present invention comprises a modified humic acid carrier, specifically, the modified humic acid carrier includes acyl chloride nano-humic acid and aminosulfonic acid. The acidic functional groups such as carboxyl and phenolic hydroxyl groups contained in humic acid can neutralize hydroxyl groups in the soil through proton exchange, thus initially regulating soil pH. However, in natural humic acid, most functional groups are encased within the macromolecular skeleton, resulting in low exposure and weak acidity, limiting its alkali-regulating efficiency when used alone. Nano-humic acid, on the other hand, has a fully opened molecular skeleton, with a greater number of exposed functional groups and increased specific surface area compared to natural humic acid. This facilitates better contact with soil alkaline ions, enhancing its pH-regulating effect; furthermore, the abundant active sites provide a foundation for subsequent chemical modification. Grafting sulfonic acid groups from aminosulfonic acid onto the surface of nano-humic acid via covalent bonds increases the density of acidic functional groups, significantly enhancing its alkali-regulating ability. Simultaneously, the hydrophilicity of the sulfonic acid groups further improves the dispersibility of humic acid in soil solution.

[0013] In addition, the humic acid carrier material also includes acidified chitosan, which is grafted onto humic acid to form a three-dimensional network structure. This structure not only slows down the dissolution rate of carbonates through encapsulation, preventing them from reacting rapidly with soil alkaline substances and causing sudden changes in local pH, thus achieving a slow release and continuous alkali adjustment effect; but also, the carboxyl and hydroxyl groups contained in acidified chitosan can combine with calcium and magnesium ions in the soil, promoting the formation of soil aggregates. At the same time, its biocompatibility can provide a colony carrier for microbial agents, improving the survival rate of microbial communities in the soil.

[0014] The microbial agents in the humic acid-based soil alkali conditioner of this invention can work synergistically. Specifically, Bacillus subtilis can secrete organic acids, such as lactic acid and acetic acid, which can help lower soil pH and produce antibacterial substances to inhibit soil-borne diseases; Short bacillus laterosporus can decompose insoluble phosphorus and potassium in the soil, improve nutrient availability, and its metabolites can enhance the crop's salt and alkali resistance; Bacillus megaterium can fix nitrogen in the air, supplement soil nitrogen sources, and further consolidate the alkali-regulating effect by improving the soil microbial community structure.

[0015] Preferably, the preparation method of acidified chitosan includes the following steps: Chitosan and citric acid are added to a solvent, stirred for 0.5 to 1 hour, and then centrifuged and washed to obtain the final product.

[0016] Preferably, the raw materials for acidified chitosan include citric acid and chitosan in a molar ratio of (0.5-3):1.

[0017] Preferably, the solvent includes ethanol or a 1% to 3% aqueous acetic acid solution.

[0018] Chitosan has poor water solubility. Modification of it can not only introduce a large number of carboxyl groups to improve water solubility, enhance its biological activity, and strengthen its binding ability with soil colloids, but also provide active sites for chemical cross-linking with nano-humic acid, thereby constructing a stable three-dimensional network slow-release structure and further optimizing the controlled-release performance of the carrier.

[0019] Preferably, the preparation method of the modified humic acid carrier includes the following steps: S1. The humic acid is ball-milled for 10-15 hours. Then, the ball-milled humic acid is added to deionized water, ultrasonically crushed, filtered, and dried to obtain nano-humic acid. S2. Add nano-humic acid to the acyl chloride solution, stir and react for 2-3 hours, then remove excess acyl chloride solution to obtain acyl chloride nano-humic acid. S3. Dissolve acyl chloride nano-humic acid and aminosulfonic acid in a solvent, react at 20-25℃ for 2-4 hours, wash and filter to obtain sulfonic acid nano-humic acid; S4. Add acidified chitosan and sulfonic acid nano-humic acid to dimethyl sulfoxide, add a catalyst, and react at a reaction temperature of 45-60℃ for 10-20 hours. After dialysis and drying, the product is obtained.

[0020] Preferably, in step S2, the acyl chloride solvent includes thionyl chloride and oxalyl chloride.

[0021] Preferably, in step S3, the solvent includes one or a mixture of several of N,N-dimethylformamide, dimethyl sulfoxide, and pyridine.

[0022] Preferably, in step S4, the catalyst comprises one or a mixture of several of diethylamine, triethylamine, and pyridine.

[0023] Preferably, in step S4, the mass ratio of sulfonic acid nano-humic acid to acidified chitosan is 1:(0.2~1).

[0024] By employing the above technical solution, humic acid is first ball-milled to mechanically break down large humic acid molecular aggregates, yielding nano-humic acid. Then, an acylation reaction is used to activate the hydroxyl groups of the nano-humic acid, converting them into highly active acyl chloride groups, laying the foundation for subsequent sulfonic acid grafting, thereby preparing acyl chloride nano-humic acid. Finally, the active groups of the acyl chloride nano-humic acid undergo esterification and amidation reactions with the carboxyl and amino groups of acidified chitosan, forming a stable three-dimensional network structure. The modified humic acid carrier obtained using this method exhibits high density of acidic functional groups, resulting in strong and long-lasting alkalinity regulation. Furthermore, the three-dimensional network structure allows for controlled release of active ingredients, preventing excessive local pH fluctuations. In addition, the modified humic acid carrier has strong binding ability to soil colloids, making it less prone to loss with irrigation water, further enhancing the slow-release capacity of humic acid.

[0025] More preferably, the humic acid-based soil alkali conditioner also includes 5 to 8 parts by weight of hydroxyapatite.

[0026] By adopting the above technical solutions, the humic acid-based soil alkali conditioner also includes hydroxyapatite. As a slow-release phosphorus and calcium source, hydroxyapatite not only slowly releases phosphorus and calcium elements under the action of organic acids secreted by microorganisms and roots, but also synergistically enhances the slow-release effect on carbonates with humic acid. By forming a humic acid-hydroxyapatite-carbonate complex, it further slows down the dissolution rate of carbonates, achieving more stable pH regulation. Simultaneously, the calcium ions provided by hydroxyapatite can exchange with sodium ions on soil colloids, enhancing the leaching and removal effect of sodium ions and fundamentally improving the structure of alkaline soils.

[0027] Secondly, the present invention provides a method for preparing a humic acid-based soil alkali conditioner, comprising the following steps: Weigh out the appropriate amount of modified humic acid carrier and prepare a dispersion with water. Add the appropriate amount of carbonate, ultrasonically disperse for 0.5 to 1 hour, dry, and then add the remaining raw materials of humic acid-based soil alkali conditioner. Mix well to obtain the final product.

[0028] The beneficial effects of this invention are: 1. This invention improves the acidic functional group density of nano-humic acid by modifying it with aminosulfonic acid, and constructs a three-dimensional network structure with acidified chitosan. Simultaneously, it combines carbonates and microbial agents to achieve highly efficient and long-lasting alkalinity adjustment. Compared to traditional inorganic acid amendments, it avoids localized pH changes that could burn crop roots, and the three-dimensional network structure delays carbonate release, ensuring a sustained alkalinity adjustment effect. This effectively solves the problems of short-lived effects and soil damage associated with traditional amendments.

[0029] 2. This invention combines multiple functions, including alkali adjustment, soil improvement, and nutrient supplementation, resulting in significant comprehensive benefits. The humic acid carrier material and hydroxyapatite synergistically promote the formation of soil aggregates, enhancing soil permeability and water and fertilizer retention capacity; the microbial agent not only assists in reducing alkali but also activates soil phosphorus and potassium and supplements nitrogen sources; hydroxyapatite and carbonates provide crops with nutrients such as phosphorus, calcium, and magnesium, preventing nutrient imbalances during soil improvement. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0031] Preparation Example Preparation Example 1: An acidified chitosan was prepared according to the following method: 1 mmol chitosan and 2 mmol citric acid were added to 60 mL of ethanol solution, and the mixture was stirred at 20 °C for 0.5 h. Preferably, the preparation method of the humic acid carrier material includes the following steps: Preparation Example 2-1: A humic acid carrier material was prepared according to the following method: S1. 1g of humic acid was ball-milled for 12 hours. Then, the ball-milled humic acid was added to deionized water, ultrasonically crushed, filtered, and dried to obtain nano-humic acid. S2. Add 1g of nano-humic acid to 10mL of thionyl chloride solution, stir and react for 2h, then remove excess thionyl chloride solution by vacuum distillation to obtain hydroxyacyl chloride nano-humic acid. S3. Dissolve 1g of nano-humic acid and 0.2g of aminosulfonic acid in mL of dimethyl sulfoxide, react at 20℃ for 3h, wash and filter to obtain sulfonic acid-based nano-humic acid. S4. Add 0.5g of citric acid-modified chitosan and 1g of sulfonic acid nano-humic acid to dimethyl sulfoxide, add diethylamine, react at 50℃ for 15h, and obtain humic acid carrier material after dialysis and drying.

[0032] Preparation Example 2-2, a modified humic acid carrier, differs from Preparation Example 2-1 only in that citric acid-modified chitosan is not added.

[0033] Preparation Example 2-3, a modified humic acid carrier, differs from Preparation Example 2-1 only in that 1g of citric acid-modified chitosan is added.

[0034] Preparation Example 2-4, a modified humic acid carrier, differs from Preparation Example 2-1 only in the addition of 0.7 g of aminosulfonic acid.

[0035] Preparation Examples 2-5: A modified humic acid carrier was prepared according to the following method: S1. 1g of humic acid was ball-milled for 12 hours. Then, the ball-milled humic acid was added to deionized water, ultrasonically crushed, filtered, and dried to obtain nano-humic acid. S2. Add 1g of nano-humic acid to 10mL of thionyl chloride solution, stir and react for 2h, then remove excess thionyl chloride solution by vacuum distillation to obtain hydroxyacyl chloride nano-humic acid. S3. Add 0.5g of citric acid-modified chitosan and 1g of sulfonated hydroxyl acyl nano-humic acid to dimethyl sulfoxide, add diethylamine, react at 50℃ for 15h, and obtain humic acid carrier material after dialysis and drying.

[0036] Preparation Example 2-6, a modified humic acid carrier, differs from Preparation Example 2-1 only in that the humic acid is not ball-milled.

[0037] Example Example 1: A humic acid-based soil alkali conditioner was prepared according to the following method: Weigh 40 parts of the humic acid carrier material prepared in Preparation Example 2-1, add it to 80 mL of water to prepare a dispersion, ultrasonically disperse for 0.5 h, dry it, and then add 12 parts of calcium carbonate and 4 parts of microbial inoculant, wherein the mass ratio of Bacillus subtilis, Bacillus retroflexus, and Bacillus megaterium is 3:1:1. After mixing evenly, a humic acid-based soil alkali conditioner is obtained.

[0038] Example 2: A humic acid-based soil alkali conditioner was prepared according to the following method: Weigh 30 parts of the humic acid carrier material prepared in Preparation Example 2-1, add it to 80 mL of water to prepare a dispersion, ultrasonically disperse for 0.5 h, dry, add 8 parts of calcium carbonate and 3 parts of microbial inoculant, wherein the mass ratio of Bacillus subtilis, Bacillus retroflexus and Bacillus megaterium is 3:1:1, mix evenly to obtain humic acid-based soil alkali conditioner.

[0039] Example 3: A humic acid-based soil alkali conditioner was prepared according to the following method: Weigh 50 parts of the humic acid carrier material prepared in Preparation Example 2-1, add it to 80 mL of water to prepare a dispersion, ultrasonically disperse for 0.5 h, dry it, and then add 15 parts of calcium carbonate and 5 parts of microbial inoculant, wherein the mass ratio of Bacillus subtilis, Bacillus retroflexus, and Bacillus megaterium is 3:1:1. After mixing evenly, a humic acid-based soil alkali conditioner is obtained.

[0040] Example 4, a humic acid-based soil alkali conditioner, differs from Example 1 only in the addition of 6 parts hydroxyapatite.

[0041] Example 5, a humic acid-based soil alkali conditioner, differs from Example 1 only in the addition of 2 parts hydroxyapatite.

[0042] Example 6, a humic acid-based soil alkali conditioner, differs from Example 1 only in the addition of 10 parts hydroxyapatite.

[0043] Comparative Example Comparative Example 1, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of the modified humic acid carrier prepared in Preparation Example 2-2 is used instead of the modified humic acid carrier prepared in Preparation Example 1.

[0044] Comparative Example 2, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of the modified humic acid carrier prepared in Preparation Example 2-3 is used to replace the modified humic acid carrier prepared in Preparation Example 1.

[0045] Comparative Example 3, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of the modified humic acid carrier prepared in Preparation Examples 2-4 is used instead of the modified humic acid carrier prepared in Preparation Example 1.

[0046] Comparative Example 4, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of the modified humic acid carrier prepared in Preparation Examples 2-5 is used instead of the modified humic acid carrier prepared in Preparation Example 1.

[0047] Comparative Example 5, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of humic acid is used to replace the modified humic acid carrier prepared in Preparation Example 1.

[0048] Comparative Example 6, a humic acid-based soil alkali conditioner, differs from Example 1 only in that an equal amount of the modified humic acid carrier prepared in Preparation Examples 2-6 is used instead of the modified humic acid carrier prepared in Preparation Example 1.

[0049] Performance testing 1. Soil pH determination: Tested according to the method specified in NY / T 1121.2-2006.

[0050] 2. Determination of soil alkalinity: The test shall be conducted in accordance with the provisions of LY / T 1249-1999 standard.

[0051] The performance of the phytic acid-based soil alkali conditioners prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was tested, and the test results are shown in Table 1.

[0052] Table 1 Performance test results According to Table 1, and in conjunction with Examples 1 and 4-6, it can be seen that the soil pH and 0-6 cm soil alkalinity in Example 4 are slightly lower than in Example 1. This is because the difference between Example 4 and Example 1 is that Example 4 adds 6 parts of hydroxyapatite, which can form a stable complex with the modified humic acid carrier, effectively delaying carbonate release and enhancing sodium ion exchange capacity, thus synergistically improving the effects of adjusting and reducing alkaliness. The soil pH and 0-6 cm soil alkalinity effects in Example 5 are comparable to those in Example 1. This is because... The difference between Example 5 and Example 1 is that Example 5 adds 2 parts of hydroxyapatite, which results in insufficient hydroxyapatite to form an effective complex. This leads to a weak auxiliary effect on carbonate slow release and sodium ion exchange, and thus cannot significantly optimize the alkali adjustment effect. The soil pH and 0-6cm soil alkalinity of Example 6 are slightly higher than those of Example 1. The reason is that the difference between Example 6 and Example 1 is that Example 6 adds 10 parts of hydroxyapatite. Excessive hydroxyapatite tends to agglomerate, hindering the contact between the acidic sites of modified humic acid and carbonates and soil alkaline ions, thus weakening the alkali adjustment efficiency.

[0053] Combining Example 1 and Comparative Examples 1-2, it can be seen that the soil pH and 0-6cm soil alkalinity of Comparative Examples 1-2 are significantly higher than those of Example 1. The reason is that Comparative Example 1 does not add acidified chitosan, so it cannot form a three-dimensional network structure to encapsulate carbonates. The rapid dissolution reaction of carbonates leads to the local pH adjustment being not lasting, and the lack of the carboxyl and hydroxyl groups of acidified chitosan promoting the soil aggregate structure results in insufficient soil colloidal stability and poor alkalinity improvement. Comparative Example 2 adds excessive acidified chitosan, which may lead to an overly dense three-dimensional network structure, which to some extent hinders the contact and reaction efficiency between acidic functional groups and soil alkaline substances, thus affecting the full realization of the alkalinity adjustment effect.

[0054] Combining Example 1 and Comparative Examples 3-4, it can be seen that the soil pH and 0-6cm soil alkalinity of Comparative Examples 3-4 are significantly higher than those of Example 1. The reason is that the difference between Comparative Example 3 and Example 1 is that Comparative Example 3 added an excessive amount of aminosulfonic acid. Excessive aminosulfonic acid will lead to an excessively high density of sulfonic acid groups on the surface of the humic acid carrier, resulting in excessive acidity, which will inhibit the activity of beneficial soil microorganisms and disrupt the soil micro-ecological balance. In addition, excessive sulfonic acid groups are easy to combine with calcium and magnesium ions in the soil to form precipitation, which will reduce the availability of nutrients and weaken the sustainability of alkalinity adjustment. Comparative Example 4 did not add aminosulfonic acid, so the nano-humic acid was not grafted with sulfonic acid groups, the density of acidic functional groups was reduced, the alkalinity adjustment ability was greatly weakened, and it could not effectively neutralize the alkaline ions in the soil, resulting in a high level of pH and alkalinity.

[0055] Combining Example 1 and Comparative Example 5, it can be seen that the soil pH and 0-6cm soil alkalinity of Comparative Example 5 are significantly higher than those of Example 1. The reason for this is that the difference between Comparative Example 5 and Example 1 is that Comparative Example 5 uses unmodified humic acid. Natural humic acid has a compact molecular skeleton, low functional group exposure rate, small specific surface area, low contact efficiency with soil alkaline ions, and lacks the strong acidity and hydrophilicity brought by nano-sizing and sulfonic acid grafting. At the same time, it cannot form a three-dimensional slow-release structure with acidified chitosan. Its alkalinity adjustment effect is short-lived and mild, making it difficult to cope with soil alkalization problems. Therefore, its improvement effect is far worse than that of the modified humic acid carrier.

[0056] Combining Example 1 and Comparative Example 6, it can be seen that the soil pH and 0-6cm soil alkalinity of Comparative Example 6 are significantly higher than those of Example 1. The reason for this is that the difference between Comparative Example 6 and Example 1 is that the humic acid used in Comparative Example 6 was not ball-milled, which prevented the large humic acid molecular aggregates from being broken down into nano-sized particles. This resulted in a compact humic acid molecular skeleton, low exposure of internally encapsulated acidic functional groups, and a significantly smaller specific surface area than nano-humic acid. Consequently, the contact area and reaction efficiency with soil alkaline ions were significantly reduced. At the same time, the non-nano-sized humic acid lacked sufficient active sites to react with aminosulfonic acid and acidified chitosan, resulting in a poor alkalinity adjustment effect.

[0057] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A humic acid-based soil alkali adjuster, characterized in that, Including the following parts by weight of raw materials: 30-50 parts of modified humic acid carrier; 8-15 parts carbonate; 3-5 parts of microbial inoculant; The raw materials for the modified humic acid carrier include acyl chloride nano-humic acid, aminosulfonic acid, and acidified chitosan in a mass ratio of 1:(0.1-0.4):(0.1-0.3).

2. The humic acid-based soil alkali conditioner according to claim 1, characterized in that, The raw materials for the acidified chitosan include citric acid and chitosan in a molar ratio of (0.5-3):

1.

3. The humic acid-based soil alkali conditioner according to claim 1, characterized in that, The preparation method of the modified humic acid carrier includes the following steps: S1. The humic acid is ball-milled for 10-15 hours. Then, the ball-milled humic acid is added to deionized water, ultrasonically crushed, filtered, and dried to obtain nano-humic acid. S2. Add nano-humic acid to the acyl chloride solution, stir and react for 2-3 hours, then remove excess acyl chloride solution to obtain acyl chloride nano-humic acid. S3. Dissolve acyl chloride nano-humic acid and aminosulfonic acid in a solvent, react at 20-25℃ for 2-4 hours, wash and filter to obtain sulfonic acid nano-humic acid; S4. Add acidified chitosan and sulfonic acid nano-humic acid to a dimethyl sulfoxide solution, add a catalyst, and react at a reaction temperature of 45-60℃ for 10-20 hours. After dialysis and drying, the product is obtained.

4. The humic acid-based soil alkali conditioner according to claim 3, characterized in that, In step S2, the acyl chloride solvent includes thionyl chloride and oxalyl chloride.

5. The humic acid-based soil alkali conditioner according to claim 3, characterized in that, In step S4, the catalyst comprises one or a mixture of several of diethylamine, triethylamine, and pyridine.

6. The humic acid-based soil alkali conditioner according to claim 3, characterized in that, In step S4, the mass ratio of the sulfonic acid nano-humic acid to the acidified chitosan is 1:(0.2~1).

7. The humic acid-based soil alkali conditioner according to claim 1, characterized in that, The carbonates include calcium carbonate and / or magnesium carbonate.

8. The humic acid-based soil alkali conditioner according to claim 1, characterized in that, The microbial agent comprises Bacillus subtilis, Bacillus lateralis, and Bacillus megaterium in a mass ratio of (2-3):(1-2):(1-2).

9. A humic acid-based soil alkali conditioner according to claim 1, characterized in that, The humic acid-based soil alkali conditioner also includes 5 to 8 parts by weight of hydroxyapatite.

10. A method for preparing a humic acid-based soil alkali conditioner, using the humic acid-based soil alkali conditioner as described in any one of claims 1-9, characterized in that, Includes the following steps: Weigh out the appropriate amount of modified humic acid carrier and prepare a dispersion with water. Add the appropriate amount of carbonate, ultrasonically disperse for 0.5 to 1 hour, dry, and then add the remaining raw materials of humic acid-based soil alkali conditioner. Mix well to obtain the final product.

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