A saline-alkali soil remediation composition and its preparation method and application

Abstract

The present application relates to the field of saline-alkali land remediation in agriculture, and in particular to a saline-alkali land soil remediation composition, and its preparation method and application. The saline-alkali land soil remediation composition, in parts by mass, comprises raw materials including: 30 to 50 parts of modified desulfurized gypsum, 20 to 40 parts of inorganic metal salts, 20 to 30 parts of modified colloids, 1 to 3 parts of microbial agents, 3 to 8 parts of fulvic acid, and 10 to 20 parts of filling powders. The saline-alkali land soil remediation composition prepared in the present application not only has an excellent saline-alkali land remediation effect, but also can effectively improve the soil structure and greatly increase its own stability. It can be effectively used in the preparation of various saline-alkali land improvers and has a very excellent market prospect.

Description

Technical Field

[0001] The present application relates to the field of saline-alkali land restoration in agriculture, and in particular to a saline-alkali land soil restoration composition, a preparation method thereof, and an application thereof. Background Art

[0002] Saline-alkali land is a type of salt accumulation, which means that the salt contained in the soil affects the normal growth of crops. According to incomplete statistics from UNESCO and FAO, the area of ​​saline-alkali land in the world is more than 1 billion hectares, of which my country has nearly 100 million hectares.

[0003] There are three main methods for improving saline-alkali soil: chemical improvement, physical improvement, and biological improvement. Among all saline-alkali land improvement technologies, chemical improvement has the advantages of low cost, quick results, and flexible and adjustable formulas. It does not rely on freshwater resources and supporting engineering facilities, and is less affected by climate. Therefore, it has been widely used in areas such as Xinjiang where freshwater resources are scarce and climate change is large. Among them, the main method of chemical improvement is to treat saline-alkali land by adding saline-alkali land conditioners to the saline-alkali land for soil improvement.

[0004] The efficacy of existing saline-alkali land improvers mainly relies on the effect of desulfurized gypsum. The calcium ions in the desulfurized gypsum react with the carbonate and bicarbonate in the soil to exchange sodium ions, thereby achieving the purpose of reducing the soil pH and alkalinity. However, the solubility of desulfurized gypsum itself is low, and the chemical reaction requires a large amount of water as a medium. At the same time, it may further increase the salinization of the soil in areas with high groundwater levels. In addition, for saline-alkali land with poor soil structure, desulfurized gypsum does not have the effect of improving the soil structure, and its own stability is poor.

[0005] Therefore, in order to solve the above problems, the present application provides a saline-alkali soil remediation composition and a preparation method thereof. The saline-alkali soil remediation composition prepared in the present application not only has an excellent saline-alkali soil remediation effect, but also can effectively improve the soil structure and greatly increase its own stability. It can be effectively used in the preparation of various saline-alkali land improvers and has a very excellent market prospect. Summary of the invention

[0006] In order to solve the above problems, the first aspect of the present application provides a saline-alkali soil remediation composition, which includes, by mass, 30 to 50 parts of modified desulfurized gypsum, 20 to 40 parts of inorganic metal salt, 20 to 30 parts of modified colloid, 1 to 3 parts of microbial agent, 3 to 8 parts of fulvic acid, and 10 to 20 parts of filling powder.

[0007] As a preferred solution, the mass ratio of the modified desulfurized gypsum, the inorganic metal salt and the modified colloid is (3.5-4.5): (2.2-3.4): (2.4-2.6).

[0008] As a preferred solution, the mass ratio of the modified desulfurized gypsum, the inorganic metal salt and the modified colloid is (3.8-4): (2.6-3.2): 2.5.

[0009] As a preferred solution, the preparation method of the modified desulfurized gypsum comprises the following steps: S1: adding desulfurized gypsum to deionized water, adding silane coupling agent and polyethylene glycol and stirring to mix evenly; S2: adding ammonia water, chitosan and tetraethyl orthosilicate to the reaction solution, heating to 50-65°C, and keeping warm for reaction for 3-4 hours; S3: after the reaction is completed, adding triethanolamine to the reaction solution, and stirring continuously for 60-80 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying and keeping warm at 60-80°C for 3-4 hours, and obtaining the product after completion.

[0010] As a preferred solution, the mass ratio of the desulfurized gypsum, the silane coupling agent, and the polyethylene glycol is (4-6): (0.5-1.5): (2-3).

[0011] As a preferred solution, the mass ratio of the desulfurized gypsum, the silane coupling agent and the polyethylene glycol is 5.5:1.2:2.8.

[0012] As a preferred solution, the mass ratio of the desulfurized gypsum, chitosan and tetraethyl orthosilicate is (4-6): (0.5-1): (1.5-2.5).

[0013] As a preferred solution, the mass ratio of tetraethyl orthosilicate to triethanolamine is (1.5-2.5):(0.8-1.6).

[0014] In this application, by adopting the above-mentioned modified desulfurized gypsum, in addition to effectively improving the improvement effect of saline-alkali land, the stability of the composition itself and the water retention rate of the soil after use can be further improved. The modified desulfurized gypsum in this application can form a multi-layer mixed coating layer formed by cross-linked chitosan and trackless silica gel on the surface of the gypsum powder particles, and further form a good affinity with water molecules through the hydrogen bonding of its surface hydroxyl and carboxyl groups. On the other hand, the multi-layer surface formed can form a rough peak-valley surface structure, and then when in contact with water, the retention of water molecules on the surface is greatly enhanced, and the formation of a surface hydration layer is accelerated, thereby greatly enhancing the affinity and solubility of the desulfurized gypsum with water, and then when in use, it can not only greatly reduce its requirements for land water level and water demand, but also ensure the water absorption and water retention performance of the soil after use.

[0015] As a preferred solution, the inorganic metal salt is at least one of superphosphate, aluminum sulfate, ferrous sulfate, potassium aluminum sulfate, potassium dihydrogen phosphate, and calcium chloride.

[0016] As a preferred solution, the inorganic metal salt is a combination of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride.

[0017] As a preferred solution, the mass ratio of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride is (3-6): (10-12): (10-15).

[0018] As a preferred solution, the mass ratio of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride is (4-5):12:14.

[0019] As a preferred scheme, the preparation method of the modified colloid comprises the following steps: S1: adding amylose and gelatin into deionized water and mixing evenly, then adding nitrous acid, stirring at 0-5°C for 40-80min, evacuating to vacuum and adding ethyl methacrylate, then adding ammonia water to adjust the pH to 6-7; S2: maintaining a speed of 200-240r / min, stirring and keeping warm at 60-75°C for 3-4h, during which an initiator is added dropwise for 0.5-1.5h at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6-7, naturally cooling to room temperature, filtering and drying to obtain the product.

[0020] As a preferred solution, the mass ratio of the amylose, gelatin and nitrous acid is (0.5~1):(3~5):(1~1.2).

[0021] As a preferred solution, the mass ratio of gelatin to ethyl methacrylate is (3-5): (1-1.5).

[0022] As a preferred solution, the initiator is potassium persulfate.

[0023] As a preferred solution, the straight chain content of the straight chain starch is 70-80%.

[0024] The addition of modified colloids in this application can greatly improve the stability of the soil remediation composition itself, and enhance its saline-alkali land improvement effect and water absorption and water retention effect. The modified gelatin can insert acrylic acid segments and long helical structures of amylose in its long chain segments. The presence of these structures can greatly enhance the degree of tight connection between the internal molecules of the colloid system, thereby inhibiting the frequent contact between the internal active groups and active molecules under the action of the external active environment, thereby greatly reducing its reaction possibility and ensuring stable properties. On the other hand, the modified gelatin system can be used as an active carrier of solid particles, and the surface of the carrier has more active groups, which can form good hydrogen bond affinity with water molecules, thereby ensuring the water absorption and water retention rate of the soil during the overall use process.

[0025] As a preferred solution, the microbial agent is EM bacteria.

[0026] As a preferred solution, the mass ratio of fulvic acid to microbial agent is (5-7): (1-2).

[0027] As a preferred solution, the mass ratio of fulvic acid to microbial agent is (5.5-6.5): (1.2-1.6).

[0028] As a preferred solution, the filler powder is at least one of bentonite, kaolin, talcum powder, diatomaceous earth, rice husk powder, jujube kernel powder and white carbon black.

[0029] As a preferred solution, the filler powder is a composition of diatomaceous earth and white carbon black.

[0030] As a preferred solution, the mass ratio of diatomaceous earth to white carbon black is (2-4): (0.5-1).

[0031] The second aspect of the present application provides a method for preparing the above-mentioned saline-alkali soil remediation composition, which comprises the following steps: heating the modified desulfurized gypsum, inorganic metal salt, modified colloid, fulvic acid, microbial agent and filler powder in a high-speed mixer to 50-60°C, stirring and mixing at a speed of 220-280 r / min, adding the mixed materials to a granulator, granulating, sieving and drying to obtain the composition.

[0032] The beneficial effects of this application are:

[0033] 1. A saline-alkali soil remediation composition provided in the present application not only has an excellent saline-alkali soil remediation effect, but can also effectively improve the soil structure and greatly increase its own stability. It can be effectively used in the preparation of various saline-alkali land improvers and has a very excellent market prospect.

[0034] 2. A saline-alkali soil remediation composition provided in the present application, wherein the modified desulfurized gypsum added therein can not only effectively improve the saline-alkali land improvement effect, but also further improve the stability of the composition itself and the water retention rate of the soil after use; the modified desulfurized gypsum can form a multi-layer mixed coating layer formed by cross-linked chitosan and trackless silica gel on the surface of the gypsum powder particles, and further form a good affinity with water molecules through the hydrogen bonding of its surface hydroxyl and carboxyl groups. On the other hand, the multi-layer surface formed by it can form a rough peak-valley surface structure, and then when it comes into contact with water, it greatly enhances the retention of water molecules on the surface, thereby accelerating the formation of a surface hydration layer.

[0035] 3. The saline-alkali soil remediation composition provided in the present application has modified desulfurized gypsum added thereto which has excellent water affinity and solubility, and thus when used, it can not only significantly reduce its requirements for land water level and water demand, but also ensure the water absorption and water retention properties of the soil after use.

[0036] 4. A saline-alkali soil remediation composition provided in the present application, the modified colloid added thereto can greatly improve the stability of the soil remediation composition itself, and enhance its saline-alkali land improvement effect and water absorption and water retention effect; the modified gelatin can insert acrylic acid segments and long helical structures of amylose in its long chain segments, and the presence of these structures can greatly enhance the degree of tight connection between the internal molecules of the colloid system, thereby inhibiting the frequent contact between the internal active groups and active molecules under the action of the external active environment, thereby greatly reducing the possibility of its reaction and ensuring the stability of the properties. On the other hand, the modified gelatin system can be used as an active carrier of solid particles, and the surface of the carrier has more active groups, which can form good hydrogen bond affinity with water molecules, thereby ensuring the water absorption and water retention rate of the soil during the overall use process. DETAILED DESCRIPTION

[0037] The following will further explain and demonstrate the technical solutions in the above invention content of this application in the form of specific implementation schemes. The following embodiments are only practical examples used to illustrate and explain the contents of the technical solutions in the specification, and should not limit the scope of the claims to be protected by this application. All technical products based on the technical solutions described in the invention content of this application should be included in the scope to be protected by this application.

[0038] In the following examples, unless otherwise specified, the raw materials are all commercially available products, or can be prepared by methods well known to those skilled in the art.

[0039] Example 1: Example 1 The first aspect provides a saline-alkali soil remediation composition, in which the raw materials include, by mass: 40 parts of modified desulfurized gypsum, 28 parts of inorganic metal salt, 25 parts of modified colloid, 1.5 parts of microbial agent, 6 parts of fulvic acid, and 15 parts of filling powder.

[0040] The preparation method of modified desulfurized gypsum includes the following steps, calculated by mass: S1: adding 5.5 parts of desulfurized gypsum to 80 parts of deionized water, adding 1.2 parts of γ-aminopropyltriethoxysilane and 2.8 parts of polyethylene glycol 400 and stirring to mix evenly; S2: adding 0.5 parts of ammonia water, 1 part of chitosan and 1.8 parts of tetraethyl orthosilicate to the reaction solution, heating to 60°C, and keeping the temperature for reaction for 3 hours; S3: after the reaction is completed, adding 1 part of triethanolamine to the reaction solution, and stirring continuously for 65 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying and keeping the temperature at 80°C for 3 hours, and obtaining the product after completion.

[0041] The desulfurized gypsum was purchased from the high-quality desulfurized gypsum products sold by Beijing Yiwei Company.

[0042] The inorganic metal salt is a composition of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride, and the mass ratio of the three is 5:12:14.

[0043] The preparation method of the modified colloid includes the following steps, calculated by mass: S1: adding 0.8 parts of amylose and 4.2 parts of gelatin to 50 parts of deionized water and mixing evenly, then adding 1.2 parts of nitrous acid, stirring at 2°C for 60 minutes, evacuating to vacuum, adding 1.4 parts of ethyl methacrylate, and then adding ammonia water to adjust the pH to 6.5; S2: maintaining a speed of 220r / min, stirring and keeping warm at 70°C for 3 hours, during which an initiator is added dropwise for 1 hour at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6.8, naturally cooling to room temperature, filtering and drying to obtain the result.

[0044] The amylose was purchased from the amylose products sold by Wuhan Huaxiang Kejie Biotechnology Co., Ltd., with an average amylose content of 74%.

[0045] The initiator is potassium persulfate.

[0046] The microbial agent EM bacteria was purchased from the EM bacteria products sold by Shandong Kunlanbinong Biotechnology Co., Ltd.

[0047] The filling powder is a composition of diatomaceous earth and white carbon black, and the mass ratio of the two is 3:0.8.

[0048] Diatomaceous earth was purchased from agricultural grade diatomaceous earth products sold by Xuyi Taihe High-tech Technology Co., Ltd.

[0049] The second aspect of this embodiment provides a method for preparing the above-mentioned saline-alkali soil remediation composition, which comprises the following steps: heating the modified desulfurized gypsum, inorganic metal salt, modified colloid, fulvic acid, microbial agent and filler powder in a high-speed mixer to 55°C, stirring and mixing at a speed of 250r / min, adding the mixed materials to a granulator, granulating, sieving and drying to obtain the composition.

[0050] Example 2: Example 2 The first aspect provides a saline-alkali soil remediation composition, in which the raw materials include, by mass: 35 parts of modified desulfurized gypsum, 22 parts of inorganic metal salt, 26 parts of modified colloid, 1.5 parts of microbial agent, 6 parts of fulvic acid, and 15 parts of filling powder.

[0051] The preparation method of modified desulfurized gypsum includes the following steps, calculated by mass: S1: adding 5.5 parts of desulfurized gypsum to 80 parts of deionized water, adding 1.2 parts of γ-aminopropyltriethoxysilane and 2.8 parts of polyethylene glycol 400 and stirring to mix evenly; S2: adding 0.5 parts of ammonia water, 1 part of chitosan and 1.8 parts of tetraethyl orthosilicate to the reaction solution, heating to 60°C, and keeping the temperature for reaction for 3 hours; S3: after the reaction is completed, adding 1 part of triethanolamine to the reaction solution, and stirring continuously for 65 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying and keeping the temperature at 80°C for 3 hours, and obtaining the product after completion.

[0052] The desulfurized gypsum was purchased from the high-quality desulfurized gypsum products sold by Beijing Yiwei Company.

[0053] The inorganic metal salt is a composition of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride, and the mass ratio of the three is 6:10:10.

[0054] The preparation method of the modified colloid includes the following steps, calculated by mass: S1: adding 0.8 parts of amylose and 4.2 parts of gelatin to 50 parts of deionized water and mixing evenly, then adding 1.2 parts of nitrous acid, stirring at 2°C for 60 minutes, evacuating to vacuum, adding 1.4 parts of ethyl methacrylate, and then adding ammonia water to adjust the pH to 6.5; S2: maintaining a speed of 220r / min, stirring and keeping warm at 70°C for 3 hours, during which an initiator is added dropwise for 1 hour at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6.8, naturally cooling to room temperature, filtering and drying to obtain the result.

[0055] The amylose was purchased from the amylose products sold by Wuhan Huaxiang Kejie Biotechnology Co., Ltd., with an average amylose content of 74%.

[0056] The initiator is potassium persulfate.

[0057] The microbial agent EM bacteria was purchased from the EM bacteria products sold by Shandong Kunlanbinong Biotechnology Co., Ltd.

[0058] The filling powder is a composition of diatomaceous earth and white carbon black, and the mass ratio of the two is 3:0.8.

[0059] Diatomaceous earth was purchased from agricultural grade diatomaceous earth products sold by Xuyi Taihe High-tech Technology Co., Ltd.

[0060] The second aspect of this embodiment provides a method for preparing the above-mentioned saline-alkali soil remediation composition, which comprises the following steps: heating the modified desulfurized gypsum, inorganic metal salt, modified colloid, fulvic acid, microbial agent and filler powder in a high-speed mixer to 55°C, stirring and mixing at a speed of 250r / min, adding the mixed materials to a granulator, granulating, sieving and drying to obtain the composition.

[0061] Comparative Example 1

[0062] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the saline-alkali soil remediation composition, in parts by mass, comprises: 60 parts of modified desulfurized gypsum, 28 parts of inorganic metal salt, 10 parts of modified colloid, 1.5 parts of microbial agent, 6 parts of fulvic acid, and 15 parts of filling powder.

[0063] Comparative Example 2

[0064] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of modified desulfurized gypsum comprises the following steps, measured by mass: S1: adding 5.5 parts of desulfurized gypsum to 80 parts of deionized water, adding 0.5 parts of ammonia water, 1 part of chitosan and 1.8 parts of tetraethyl orthosilicate to the reaction solution, heating to 60°C, and keeping the temperature for reaction for 3 hours; S2: after the reaction is completed, adding 1 part of triethanolamine to the reaction solution, and stirring continuously for 65 minutes; S3: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying at 80°C for 3 hours, and obtaining the product after completion.

[0065] Comparative Example 3

[0066] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of modified desulfurized gypsum comprises the following steps, measured in parts by mass: S1: adding 10 parts of desulfurized gypsum to 80 parts of deionized water, adding 0.8 parts of γ-aminopropyltriethoxysilane and 2 parts of polyethylene glycol 400 and stirring to mix evenly; S2: adding 0.5 parts of ammonia water, 1 part of chitosan and 1.8 parts of tetraethyl orthosilicate to the reaction solution, heating to 60°C, and keeping the temperature for reaction for 3 hours; S3: after the reaction is completed, adding 1 part of triethanolamine to the reaction solution, and stirring continuously for 65 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying at 80°C for 3 hours, and obtaining the product after completion.

[0067] Comparative Example 4

[0068] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of modified desulfurized gypsum comprises the following steps, measured in parts by mass: S1: adding 5.5 parts of desulfurized gypsum to 80 parts of deionized water, adding 1.2 parts of γ-aminopropyltriethoxysilane and 2.8 parts of polyethylene glycol 400 and stirring to mix evenly; S2: adding 0.5 parts of ammonia water, 3 parts of chitosan and 3.8 parts of tetraethyl orthosilicate to the reaction solution, heating to 60°C, and keeping the temperature for reaction for 3 hours; S3: after the reaction is completed, adding 2.8 parts of triethanolamine to the reaction solution, and stirring continuously for 65 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven for drying at 80°C for 3 hours, and obtaining the product after completion.

[0069] Comparative Example 5

[0070] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified colloid comprises the following steps, measured in parts by mass: S1: adding 2.2 parts of amylose and 2 parts of gelatin to 60 parts of deionized water and mixing evenly, then adding 0.6 parts of nitrous acid, stirring at 2°C for 60 minutes, evacuating to vacuum, adding 1.4 parts of ethyl methacrylate, and then adding ammonia water to adjust the pH to 6.5; S2: maintaining a speed of 220r / min, stirring and keeping warm at 70°C for 3 hours, during which an initiator is added dropwise for 1 hour at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6.8, naturally cooling to room temperature, filtering and drying.

[0071] Comparative Example 6

[0072] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified colloid comprises the following steps, measured in parts by mass: S1: adding 0.8 parts of amylose and 8 parts of gelatin to 50 parts of deionized water and mixing evenly, then adding 1.2 parts of nitrous acid, stirring at 2°C for 60 minutes, evacuating to vacuum, adding 0.6 parts of ethyl methacrylate, and then adding ammonia water to adjust the pH to 6.5; S2: maintaining a speed of 220r / min, stirring and keeping warm at 70°C for 3 hours, during which an initiator is added dropwise for 1 hour at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6.8, naturally cooling to room temperature, filtering and drying.

[0073] Comparative Example 7

[0074] The specific implementation of this comparative example is basically the same as that of Example 1, except that the amylopectin was purchased from a amylopectin product sold by Wuhan Huaxiang Kejie Biotechnology Co., Ltd., and the average amylopectin content was 70%.

[0075] Performance Evaluation

[0076] 1. Salt-alkali improvement test: The grape planting plots in Changji City, Xinjiang, were divided into 9 areas of 2 mu, the land salt content was 9.2 g / kg, and the pH value was 10.6. During the test, the 9 plots were plowed 35 cm, and the soil remediation compositions prepared in the above embodiments and comparative examples were spread respectively, with a spreading amount of 200 kg / mu. After that, the soil was plowed and buried to mix evenly. After keeping it for 7 days, the salt content of the soil was detected, and the measured value was taken as the average value of 10 tests and recorded in Table 1.

[0077] 2. Moisture content: The test method of Example 1 was used to test the water retention rate of the soil (mass percentage of soil retained moisture content) after 7 days. The measured value was taken as the average value of 10 tests and recorded in Table 1.

[0078] 3. Stability test: The soil remediation compositions prepared in the examples and comparative examples were placed in a constant temperature and humidity chamber at 60±3°C and 75% humidity for 5 days. After 5 days, the samples were taken out to observe whether there were obvious adhesion, caking, hydration and deterioration. If there were, it was recorded as unqualified, otherwise it was qualified. 50 samples were tested for each example and comparative example, and the qualified rate was recorded in Table 1.

[0079]

[0080] It can be seen from the data results of the embodiments and comparative examples of the present application and Table 1 that the embodiments 1 and 2 of the present application have obvious performance advantages over comparative examples 1 to 7 in terms of saline-alkali improvement effect, soil water retention rate and self-stability. Embodiments 1 and 2 adopt the technical scheme defined in the present application, which can greatly improve the stability of the soil remediation composition itself, and enhance its saline-alkali land improvement effect and water absorption and water retention effect; the modified gelatin can insert acrylic acid segments and long helical structures of amylose in its long chain segments, and the presence of these structures can greatly enhance the degree of tight connection between the internal molecules of the colloid system, thereby inhibiting the frequent contact between the internal active groups and the active molecules under the action of the external active environment, thereby greatly reducing the possibility of its reaction and ensuring stable properties. On the other hand, the modified gelatin system can be used as an active carrier of solid particles, and the surface of the carrier has more active groups, which can form good hydrogen bond affinity with water molecules, thereby ensuring the water absorption and water retention rate of the soil during the overall use process.

Claims

1. A saline-alkali soil remediation composition, characterized in that: The raw materials include, by weight: 30-50 parts of modified desulfurized gypsum, 20-40 parts of inorganic metal salt, 20-30 parts of modified colloid, 1-3 parts of microbial agent, 3-8 parts of fulvic acid, and 10-20 parts of filling powder; The preparation method of the modified desulfurized gypsum comprises the following steps: S1: adding desulfurized gypsum to deionized water, adding silane coupling agent and polyethylene glycol, stirring and mixing evenly; S2: adding ammonia water, chitosan and tetraethyl orthosilicate to the reaction solution, heating to 50-65°C, and keeping the temperature for reaction for 3-4 hours; S3: after the reaction is completed, adding triethanolamine to the reaction solution, and stirring continuously for 60-80 minutes; S4: after the stirring is completed, filtering the product and placing it in a ventilated oven at 60-80°C for drying and keeping the temperature for 3-4 hours, and obtaining the product after completion; The mass ratio of the desulfurized gypsum, silane coupling agent and polyethylene glycol is (4-6): (0.5-1.5): (2-3); The mass ratio of the desulfurized gypsum, chitosan and tetraethyl orthosilicate is (4-6): (0.5-1): (1.5-2.5); The inorganic metal salt is at least one of superphosphate, aluminum sulfate, ferrous sulfate, potassium aluminum sulfate, potassium dihydrogen phosphate, and calcium chloride; The preparation method of the modified colloid comprises the following steps: S1: adding amylose and gelatin into deionized water and mixing evenly, then adding nitrous acid, stirring at 0-5°C for 40-80min, evacuating to vacuum and adding ethyl methacrylate, then adding ammonia water to adjust the pH to 6-7; S2: maintaining a speed of 200-240r / min, stirring and heat-insulating at 60-75°C for 3-4h, during which an initiator is added dropwise for 0.5-1.5h at the beginning of the reaction; S3: after the reaction is completed, adding ammonia water for a second time to adjust the pH to 6-7, naturally cooling to room temperature, filtering and drying to obtain the modified colloid; The mass ratio of amylose, gelatin and nitrous acid is (0.5-1): (3-5): (1-1.2); The filler powder is a composition of diatomaceous earth and white carbon black; The mass ratio of the diatomaceous earth to white carbon black is (2-4): (0.5-1).

2. The saline-alkali soil remediation composition according to claim 1, characterized in that: The mass ratio of the modified desulfurized gypsum, the inorganic metal salt and the modified colloid is (3.5-4.5): (2.2-3.4): (2.4-2.6).

3. The saline-alkali soil remediation composition according to claim 2, characterized in that: The inorganic metal salt is a combination of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride.

4. The saline-alkali soil remediation composition according to claim 3, characterized in that: The mass ratio of potassium dihydrogen phosphate, aluminum sulfate and calcium chloride is (3-6): (10-12): (10-15).

5. The saline-alkali soil remediation composition according to claim 4, characterized in that: The straight chain content of the straight chain starch is 70-80%.

6. The saline-alkali soil remediation composition according to claim 5, characterized in that: The microbial agent is EM bacteria.

7. The saline-alkali soil remediation composition according to claim 6, characterized in that: The mass ratio of fulvic acid to microbial agent is (5-7): (1-2).

8. A method for preparing the saline-alkali soil remediation composition according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: heating the modified desulfurized gypsum, inorganic metal salt, modified colloid, fulvic acid, microbial agent and filling powder in a high-speed mixer to 50-60°C, stirring and mixing at a speed of 220-280r / min, adding the mixed materials into a granulator, granulating, sieving and drying to obtain the product.

9. Use of the saline-alkali soil remediation composition according to any one of claims 1 to 7 in the preparation of a saline-alkali land improver.

Images