Humic acid soil conditioner for coastal saline-alkali soil and preparation method thereof

Abstract

The invention relates to the technical field of improvement of coastal saline-alkali soil, in particular to a humic acid soil conditioner for coastal saline-alkali soil and a preparation method of the humic acid soil conditioner. The humic acid soil conditioner is prepared from the following raw material components in parts by mass: 40 to 60 parts of cow dung, 10 to 30 parts of vinegar residues, 25 to 45 parts of compound humic acid slurry, 4 to 8 parts of medium trace element fertilizer, 25 to 55 parts of compound microorganisms, 8 to 14 parts of desulfurized gypsum and 30 to 40 parts of sodium lignin sulfonate composite material, the invention discloses a humic acid soil conditioner for coastal saline-alkali soil and a preparation method of the humic acid soil conditioner. The soil conditioner prepared by the invention can effectively reduce the soil bulk density, increase the soil aggregate content and improve the quality of coastal saline-alkali soil; the soil pH is reduced, and the soil sodium adsorption ratio is reduced.

Description

Technical Field

[0001] This application relates to the technical field of coastal saline-alkali land improvement, and in particular to a humic acid soil conditioner for coastal saline-alkali land and its preparation method. Background Technology

[0002] Coastal saline-alkali land is one of the world's important soil resource types. Its formation is closely related to factors such as seawater infiltration, high groundwater levels, and intense evaporation, and it is characterized by high salinity, high alkalinity, high alkalinity, and poor soil structure. Due to the high degree of soil salinization and the difficulty in improving it, coastal saline-alkali land has become a key bottleneck restricting the improvement of regional agricultural productivity.

[0003] Currently, international research and practice on saline-alkali land improvement have made some progress, including physical, chemical, and biological methods. However, these methods still suffer from high costs, poor adaptability, and significant environmental impact in practical applications. In recent years, humic acid, due to its rich functional groups, excellent soil-improving properties, and eco-friendly characteristics, has become an important development direction for saline-alkali land improvement. Existing technologies have conducted research on the application of humic acid materials in saline-alkali land improvement, resulting in large-scale production processes and supporting technologies, which have been extended to agricultural planting and environmental remediation. However, these products are mostly designed for general-purpose saline-alkali land and lack adaptability to the special environments of coastal saline-alkali land characterized by high salinity, high alkalinity, and high osmotic pressure.

[0004] The development of special humic acid materials for coastal saline-alkali land is still in its early stages. Existing products generally have the following problems: (1) They are single-component and rely solely on the general adsorption capacity of humic acid, making it difficult to synergistically address the Na+ in coastal saline-alkali land. + Cl - SO4 2- (1) Multiple ion poisoning and high pH stress; (2) The formula lacks specificity and does not combine the special physicochemical properties of coastal soil for functional optimization, resulting in unstable improvement effect; (3) Insufficient long-term effect, it is easy to cause functional decay due to ion competitive adsorption or microbial degradation in high salinity environment, making it difficult to meet the long-term improvement needs of coastal saline-alkali land.

[0005] Therefore, developing a specialized soil conditioner for the complex environment of coastal saline-alkali land, and enhancing its salt adsorption capacity, pH regulation ability, and soil structure improvement effect through the synergistic effect of multiple components, has become an urgent technical problem to be solved in the field of coastal saline-alkali land management. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application provides a humic acid-based soil conditioner for coastal saline-alkali land and its preparation method.

[0007] In a first aspect, this application provides a humic acid-based soil conditioner for coastal saline-alkali land, employing the following technical solution: A humic acid soil conditioner for coastal saline-alkali land comprises the following raw material components in parts by weight: 40-60 parts cow manure, 10-30 parts vinegar residue, 25-45 parts compound humic acid slurry, 4-8 parts micronutrient fertilizer, 25-55 parts compound microorganisms, 8-14 parts desulfurized gypsum, and 30-40 parts sodium lignosulfonate composite material.

[0008] This application improves the raw materials by adding cow manure and vinegar residue, which can provide organic matter, nutrients, and microorganisms to the soil, systematically improve the soil's physical structure, water retention and aeration, while balancing nutrients, buffering pH, and activating the soil's biological activity. The added composite humic acid slurry (including bio-humic acid and mineral-derived humic acid) can quickly provide organic matter to coastal saline-alkali soils lacking organic matter. In alkaline soils, the acidic functional groups of humic acid release H+. + Exchange with metal ions, H + With OH - The addition of desulfurized gypsum can reduce soil alkalinity by combining with H2O; the addition of sodium lignosulfonate composite material can not only regulate soil charge balance, improve aggregate structure, enhance nutrient retention capacity, and reduce nutrient loss, but also improve water and air conditions, passivate pollutants, and promote microbial activity.

[0009] By adopting the above technical solution, the soil conditioner prepared in this application through the synergistic effect of the various components, including cow manure, vinegar residue, composite humic acid slurry, micronutrient fertilizer, composite microorganisms, desulfurized gypsum, and sodium lignosulfonate composite material, can provide organic matter, nutrients, and microorganisms to the soil, systematically improve the soil physical structure, retain water and allow it to breathe, while balancing nutrients, buffering pH, activating the biological activity of the soil, and adsorbing heavy metals in the soil to repair the soil.

[0010] Preferably, the sodium lignosulfonate composite material comprises the following raw material components in parts by weight: 5-15 parts sodium lignosulfonate, 0.1-1 parts sodium hydroxide, 1-5 parts diethylenetriamine, 3.5-5.5 parts formaldehyde, 2-8 parts lignin, and 80-100 parts concentrated sulfuric acid.

[0011] Preferably, the preparation method of the sodium lignosulfonate composite material includes the following steps: Sodium lignosulfonate and sodium hydroxide were mixed, then diethylenetriamine was added and mixed again, followed by the addition of formaldehyde and the mixture was filtered to obtain the first mixture. The lignin and concentrated sulfuric acid were mixed and filtered to obtain a second mixture; The first mixture and the second mixture are mixed to obtain a sodium lignosulfonate composite material.

[0012] By adopting the above technical solution, sodium hydroxide and diethylenetriamine are used to amination and modify sodium lignosulfonate to introduce amino groups and increase adsorption active sites, thereby preparing the first mixture. In this application, lignin is modified with concentrated sulfuric acid to introduce oxygen-containing functional groups into the structure of lignin, thereby preparing a second mixture; The sodium lignosulfonate composite material was prepared by mixing the first mixture and the second mixture.

[0013] The prepared sodium lignosulfonate composite material can not only regulate soil charge balance, improve aggregate structure, enhance nutrient retention capacity, and reduce nutrient loss, but also improve water and air conditions, passivate pollutants, and promote microbial activity.

[0014] Preferably, the sodium lignosulfonate composite material further includes 15-25 parts by weight of chitosan / sodium lignosulfonate composite material.

[0015] Preferably, the chitosan / sodium lignosulfonate composite material comprises the following raw material components in parts by weight: 10-20 parts modified starch, 8-12 parts modified sodium lignosulfonate, and 0.02-0.2 parts chitosan hydrochloride.

[0016] Preferably, the modified starch comprises the following raw material components in parts by weight: 0.5-1.5 parts starch, 0.6-1.6 parts vinyltriethoxysilane, and 0.05-0.1 parts sodium methoxide.

[0017] Preferably, the modified sodium lignosulfonate comprises the following raw material components in parts by weight: 0.5-1.5 parts sodium lignosulfonate, 25-35 parts sodium hydroxide, and 10-14 parts chloroform.

[0018] Preferably, the preparation method of the chitosan / sodium lignosulfonate composite material includes the following steps: Preparation of modified starch: Starch is gelatinized to obtain gelatinized starch; Gelatinized starch and vinyltriethoxysilane were mixed, and sodium methoxide was added and mixed to obtain modified starch. Preparation of modified sodium lignosulfonate: Sodium lignosulfonate and sodium hydroxide were mixed, and chloroform was added to obtain modified sodium lignosulfonate. Preparation of composite materials: Modified sodium lignosulfonate and chitosan hydrochloride were mixed, and then modified starch was added and mixed to obtain a chitosan / sodium lignosulfonate composite material.

[0019] By adopting the above technical solution, this application prepares a chitosan / sodium lignin sulfonate composite material by gelatinizing starch and modifying the gelatinized starch with vinyltriethoxysilane, and then mixing the modified starch with modified sodium lignin sulfonate and chitosan hydrochloride.

[0020] The prepared chitosan / sodium lignosulfonate composite material can optimize the physical structure of soil, prevent the formation of aggregates, regulate soil porosity, retain nutrients, buffer soil pH, passivate heavy metals, and enhance soil biological activity, thus significantly improving soil fertility and crop health. At the same time, the added chitosan / sodium lignosulfonate composite material can adsorb heavy metal ions in the soil and remediate the soil.

[0021] Preferably, the composite microorganism comprises the following raw material components in parts by weight: 10-20 parts of Bacillus subtilis, 10-20 parts of Bacillus megaterium, and 5-15 parts of Azotobacter chrysophyll.

[0022] Secondly, this application provides a method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, using the following technical solution: A method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, comprising the following steps: A soil conditioner is obtained by mixing cow dung, vinegar residue, compound humic acid slurry, micronutrient fertilizer, compound microorganisms, desulfurized gypsum, and sodium lignosulfonate composite material, and then drying it.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. This application discloses a humic acid-based soil conditioner for coastal saline-alkali land and its preparation method. The soil conditioner prepared by this application can effectively reduce soil bulk density, increase soil aggregate content, improve the quality of coastal saline-alkali soil, reduce soil pH, and reduce soil sodium adsorption ratio. 2. Treatment with the soil conditioner and base fertilizer prepared in this application can significantly increase the yield of crops grown in coastal saline-alkali soil. Detailed Implementation

[0024] The technical solutions of this application are further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0025] All raw materials involved in this application are commercially available products, among which, Starch, specifically tapioca starch, was purchased from Shanghai Yuanye Biotechnology Co., Ltd. Vinyltriethoxysilane and sodium methoxide were both purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Sodium lignosulfonate and chitosan hydrochloride were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Diethylenetriamine, purchased from Sinopharm Chemical Reagent Co., Ltd.; Lignin, alkali lignin, purchased from Aladdin; Desulfurized gypsum was purchased from Tianjin Dongli Power Plant; The vinegar residue was purchased from Tianjin Jinghai County Duliu Tianli Vinegar Factory Co., Ltd. The humic acid is potassium humate with a humic acid content ≥60wt.% and an organic matter content ≥70wt.%; purchased from Henan Xinlianxin Group. The compound microorganisms consist of Bacillus subtilis (active content ≥200×10⁸ CFU / g), Bacillus megaterium (active content ≥100×10⁸ CFU / g), and Azotobacter chrysotrichum (active content ≥30×10⁸ CFU / g). All of the above components were purchased from Yangzhou Herrenknecht Biotechnology Co., Ltd., and the bacterial powders were directly mixed in proportion before use.

[0026] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0027] Preparation Example 1: Preparation of chitosan / sodium lignosulfonate composite material: The chitosan / sodium lignosulfonate composite material comprises the following raw material components: 15g modified starch, 10g modified sodium lignosulfonate, and 0.1g chitosan hydrochloride.

[0028] The modified starch comprises the following raw material components: 1g starch, 1.2g vinyltriethoxysilane, and 0.08g sodium methoxide.

[0029] Modified sodium lignosulfonate comprises the following raw material components: 1g sodium lignosulfonate, 30g sodium hydroxide, and 12g chloroform.

[0030] The preparation method of chitosan / sodium lignosulfonate composite material is as follows: (1) Preparation of modified starch: Mix starch and 100 mL of water, and gelatinize at 75°C for 20 minutes to obtain gelatinized starch; After mixing gelatinized starch and 100g of N,N-dimethylformamide for 10 minutes, vinyltriethoxysilane was added and mixed for 20 minutes. Then, 0.08g of sodium methoxide and 5mL of methanol were added and mixed at 75℃ for 100 minutes to obtain modified starch. (2) Preparation of modified sodium lignosulfonate: Sodium lignosulfonate, sodium hydroxide, and 100 mL of water were mixed and reacted at 70 °C for 100 minutes. Then, chloroform was added and the mixture was stirred for 30 minutes to obtain modified sodium lignosulfonate. Preparation of composite materials: After mixing modified sodium lignosulfonate and 50 mL of water, chitosan hydrochloride was added and mixed. The mixture was stirred at 35 °C for 20 minutes, and then modified starch was added and mixed for 2 hours to obtain a chitosan / sodium lignosulfonate composite material.

[0031] Preparation Example 2: Preparation of chitosan / sodium lignosulfonate composite material: The chitosan / sodium lignin sulfonate composite material comprises the following raw material components: 10g modified starch, 8g modified sodium lignin sulfonate, and 0.02g chitosan hydrochloride.

[0032] The modified starch comprises the following raw material components: 0.5g starch, 0.6g vinyltriethoxysilane, and 0.05g sodium methoxide.

[0033] Modified sodium lignosulfonate comprises the following raw material components: 0.5g sodium lignosulfonate, 25g sodium hydroxide, and 10g chloroform.

[0034] The preparation method of chitosan / sodium lignosulfonate composite material is as follows: (1) Preparation of modified starch: Mix starch and 100 mL of water, and gelatinize at 75°C for 20 minutes to obtain gelatinized starch; After mixing gelatinized starch and 100g of N,N-dimethylformamide for 10 minutes, vinyltriethoxysilane was added and mixed for 20 minutes. Then, 0.08g of sodium methoxide and 5mL of methanol were added and mixed at 75℃ for 100 minutes to obtain modified starch. (2) Preparation of modified sodium lignosulfonate: Sodium lignosulfonate, sodium hydroxide, and 100 mL of water were mixed and reacted at 70 °C for 100 minutes. Then, chloroform was added and the mixture was stirred for 30 minutes to obtain modified sodium lignosulfonate. Preparation of composite materials: After mixing modified sodium lignosulfonate and 50 mL of water, chitosan hydrochloride was added and mixed. The mixture was stirred at 35 °C for 20 minutes, and then modified starch was added and mixed for 2 hours to obtain a chitosan / sodium lignosulfonate composite material.

[0035] Preparation Example 3: Preparation of chitosan / sodium lignosulfonate composite material: The chitosan / sodium lignin sulfonate composite material comprises the following raw material components: 20g modified starch, 12g modified sodium lignin sulfonate, and 0.2g chitosan hydrochloride.

[0036] The modified starch comprises the following raw material components: 1.5g starch, 1.6g vinyltriethoxysilane, and 0.1g sodium methoxide.

[0037] Modified sodium lignosulfonate comprises the following raw material components: 1.5g sodium lignosulfonate, 35g sodium hydroxide, and 14g chloroform.

[0038] The preparation method of chitosan / sodium lignosulfonate composite material is as follows: (1) Preparation of modified starch: Mix starch and 100 mL of water, and gelatinize at 75°C for 20 minutes to obtain gelatinized starch; After mixing gelatinized starch and 100g of N,N-dimethylformamide for 10 minutes, vinyltriethoxysilane was added and mixed for 20 minutes. Then, 0.08g of sodium methoxide and 5mL of methanol were added and mixed at 75℃ for 100 minutes to obtain modified starch. (2) Preparation of modified sodium lignosulfonate: Sodium lignosulfonate, sodium hydroxide, and 100 mL of water were mixed and reacted at 70 °C for 100 minutes. Then, chloroform was added and the mixture was stirred for 30 minutes to obtain modified sodium lignosulfonate. Preparation of composite materials: After mixing modified sodium lignosulfonate and 50 mL of water, chitosan hydrochloride was added and mixed. The mixture was stirred at 35 °C for 20 minutes, and then modified starch was added and mixed for 2 hours to obtain a chitosan / sodium lignosulfonate composite material.

[0039] Preparation Example 4: Preparation of sodium lignosulfonate composite materials: The sodium lignosulfonate composite material comprises the following raw material components: 10g sodium lignosulfonate, 0.5g sodium hydroxide, 3g diethylenetriamine, 4.5g formaldehyde, 5g lignin, 90g concentrated sulfuric acid, and 20g chitosan / sodium lignosulfonate composite material.

[0040] The chitosan / sodium lignosulfonate composite material was prepared in Preparation Example 1.

[0041] The preparation method of sodium lignosulfonate composite material is as follows: Sodium lignosulfonate, sodium hydroxide, and 60 mL of water were mixed for 10 minutes. Diethylenetriamine was added and mixed for another 10 minutes. The mixture was then heated to 85°C, and formaldehyde was added and mixed for 3 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain the first mixture. Lignin and concentrated sulfuric acid were mixed and reacted at 210°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain a second mixture. Mix the first mixture, the second mixture, and 200 mL of water for 30 minutes, then add the chitosan / sodium lignosulfonate composite material and mix for another 20 minutes to obtain the sodium lignosulfonate composite material.

[0042] Preparation Example 5: Preparation of sodium lignosulfonate composite materials: The sodium lignosulfonate composite material comprises the following raw material components: 5g sodium lignosulfonate, 0.1g sodium hydroxide, 1g diethylenetriamine, 3.5g formaldehyde, 2g lignin, 80g concentrated sulfuric acid, and 15g chitosan / sodium lignosulfonate composite material.

[0043] The chitosan / sodium lignin sulfonate composite material was prepared in Preparation Example 2.

[0044] The preparation method of sodium lignosulfonate composite material is as follows: Sodium lignosulfonate, sodium hydroxide, and 60 mL of water were mixed for 10 minutes. Diethylenetriamine was added and mixed for another 10 minutes. The mixture was then heated to 85°C, and formaldehyde was added and mixed for 3 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain the first mixture. Lignin and concentrated sulfuric acid were mixed and reacted at 210°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain a second mixture. Mix the first mixture, the second mixture, and 200 mL of water for 30 minutes, then add the chitosan / sodium lignosulfonate composite material and mix for another 20 minutes to obtain the sodium lignosulfonate composite material.

[0045] Preparation Example 6: Preparation of sodium lignosulfonate composite materials: The sodium lignosulfonate composite material comprises the following raw material components: 15g sodium lignosulfonate, 1g sodium hydroxide, 5g diethylenetriamine, 5.5g formaldehyde, 8g lignin, 100g concentrated sulfuric acid, and 25g chitosan / sodium lignosulfonate composite material.

[0046] The chitosan / sodium lignosulfonate composite material was prepared in Preparation Example 3.

[0047] The preparation method of sodium lignosulfonate composite material is as follows: Sodium lignosulfonate, sodium hydroxide, and 60 mL of water were mixed for 10 minutes. Diethylenetriamine was added and mixed for another 10 minutes. The mixture was then heated to 85°C, and formaldehyde was added and mixed for 3 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain the first mixture. Lignin and concentrated sulfuric acid were mixed and reacted at 210°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain a second mixture. Mix the first mixture, the second mixture, and 200 mL of water for 30 minutes, then add the chitosan / sodium lignosulfonate composite material and mix for another 20 minutes to obtain the sodium lignosulfonate composite material.

[0048] Example 1: A humic acid soil conditioner for coastal saline-alkali land comprises the following raw material components: 50g cow manure, 20g vinegar residue (fineness 20 mesh), 35g compound humic acid slurry, 6g micronutrient fertilizer, 40g compound microorganisms, 11g desulfurized gypsum, and 35g sodium lignosulfonate composite material. Cow dung, well-rotted cow dung, with an organic matter content of 35%; The micronutrient fertilizers include H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer, wherein the weight ratio of H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer is 10:60:13:5:4:3.

[0049] The sodium lignosulfonate composite material was prepared in Preparation Example 4.

[0050] The compound microorganisms include the following raw material components: 15g of Bacillus subtilis, 15g of Bacillus megaterium, and 10g of Azotobacter chrysophyte.

[0051] A method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, comprising the following steps: Step 1: Preparation of Composite Humic Acid Slurry (1) Disperse 10g of humic acid in 50ml of deionized water, add potassium hydroxide to adjust the pH to 9-10, stir at 95℃ for 1h to obtain a solution; add 4% formaldehyde and 8% sodium sulfite by mass of humic acid to the solution, stir at 95℃ and 0.1MPa for 1h, and sterilize to obtain mineral humic acid slurry; (2) The lignite was first crushed and sieved using a ball mill to obtain a sample with a particle size of 0.125-0.250 mm. The sample was then soaked in 10 mol / L nitric acid for 48 h to oxidize it. After washing with deionized water until neutral, the sample was dried and sterilized to obtain a pretreated coal sample. 80 g of coal sample and 10 g of mineral humic acid slurry were added to 10 mL of compound fermentation liquid. After mixing evenly, the moisture content was adjusted to 65%. The mixture was fermented at 28 °C for 10 days. After the fermentation was completed, a compound humic acid slurry was obtained. The compound fermentation liquid was a mixture of Bacillus subtilis, Bacillus megaterium and Azotobacter chrysophagus in a mass ratio of 2:2:1.

[0052] Step 2: Preparation of Soil Conditioner Cow manure, vinegar residue, compound humic acid slurry, micronutrient fertilizer, desulfurized gypsum, sodium lignosulfonate composite material, and 500 mL of water were mixed at 400 rpm for 2 hours. Compound microorganisms were then added, and the mixture was stirred at 400 rpm for 30 minutes. The mixture was then dried to obtain a soil conditioner. Example 2: A humic acid soil conditioner for coastal saline-alkali land comprises the following raw material components: 40g cow manure, 10g vinegar residue (fineness 20 mesh), 25g compound humic acid slurry, 4g micronutrient fertilizer, 25g compound microorganisms, 8g desulfurized gypsum, and 30g sodium lignosulfonate composite material. Cow dung, well-rotted cow dung, with an organic matter content of 35%; The micronutrient fertilizers include H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer, wherein the weight ratio of H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer is 10:60:13:5:4:3.

[0053] The sodium lignosulfonate composite material was prepared in Preparation Example 5.

[0054] The compound microorganisms include the following raw material components: 10g of Bacillus subtilis, 10g of Bacillus megaterium, and 5g of Azotobacter chrysophyte.

[0055] A method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, comprising the following steps: Step 1: Preparation of Composite Humic Acid Slurry (1) Disperse 10g of humic acid in 50ml of deionized water, add potassium hydroxide to adjust the pH to 9-10, stir at 95℃ for 1h to obtain a solution; add 4% of formaldehyde by mass of humic acid and 8% of sodium sulfite by mass of humic acid to the solution, stir at 95℃ and 0.1MPa for 1h, and sterilize to obtain mineral humic acid slurry.

[0056] (2) The lignite was first crushed and sieved using a ball mill to obtain a sample with a particle size of 0.125-0.250 mm. The sample was then soaked in 10 mol / L nitric acid for 48 h to oxidize it. After washing with deionized water until neutral, the sample was dried and sterilized to obtain a pretreated coal sample. 80 g of coal sample and 10 g of mineral humic acid slurry were added to 10 mL of compound fermentation liquid. After mixing evenly, the moisture content was adjusted to 65%. The mixture was fermented at 28 °C for 10 days. After the fermentation was completed, a compound humic acid slurry was obtained. The compound fermentation liquid was a mixture of Bacillus subtilis, Bacillus megaterium and Azotobacter chrysophagus in a mass ratio of 2:2:1.

[0057] Step 2: Preparation of Soil Conditioner Cow manure, vinegar residue, compound humic acid slurry, micronutrient fertilizer, desulfurized gypsum, sodium lignosulfonate composite material, and 500 mL of water were mixed at 400 rpm for 2 hours. Then, compound microorganisms were added and mixed at 400 rpm for 30 minutes. The mixture was then dried to obtain a soil conditioner.

[0058] Example 3: A humic acid soil conditioner for coastal saline-alkali land includes the following raw material components: 60g cow manure, 30g vinegar residue (fineness 20 mesh), 45g compound humic acid slurry, 8g trace element fertilizer, 55g compound microorganisms, 14g desulfurized gypsum, and 40g sodium lignosulfonate composite material. Cow dung, well-rotted cow dung, with an organic matter content of 35%; The micronutrient fertilizers include H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer, wherein the weight ratio of H2SiO3 fertilizer, CaO fertilizer, MgO fertilizer, CuSO4 fertilizer, ZnSO4 fertilizer and FeSO4 fertilizer is 10:60:13:5:4:3.

[0059] The sodium lignosulfonate composite material was prepared in Preparation Example 6.

[0060] The compound microorganisms include the following raw material components: 20g of Bacillus subtilis, 20g of Bacillus megaterium, and 15g of Azotobacter chrysophyte.

[0061] A method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, comprising the following steps: Step 1: Preparation of Composite Humic Acid Slurry (1) Disperse 10g of humic acid in 50ml of deionized water, add potassium hydroxide to adjust the pH to 9-10, stir at 95℃ for 1h to obtain a solution; add 4% of formaldehyde by mass of humic acid and 8% of sodium sulfite by mass of humic acid to the solution, stir at 95℃ and 0.1MPa for 1h, and sterilize to obtain mineral humic acid slurry.

[0062] (2) The lignite was first crushed and sieved using a ball mill to obtain a sample with a particle size of 0.125-0.250 mm. The sample was then soaked in 10 mol / L nitric acid for 48 h to oxidize it. After washing with deionized water until neutral, the sample was dried and sterilized to obtain a pretreated coal sample. 80 g of coal sample and 10 g of mineral humic acid slurry were added to 10 mL of compound fermentation liquid. After mixing evenly, the moisture content was adjusted to 65%. The mixture was fermented at 28 °C for 10 days. After the fermentation was completed, a compound humic acid slurry was obtained. The compound fermentation liquid was a mixture of Bacillus subtilis, Bacillus megaterium and Azotobacter chrysophagus in a mass ratio of 2:2:1.

[0063] Step 2: Preparation of Soil Conditioner Cow manure, vinegar residue, compound humic acid slurry, micronutrient fertilizer, desulfurized gypsum, sodium lignosulfonate composite material, and 500 mL of water were mixed at 400 rpm for 2 hours. Then, compound microorganisms were added and mixed at 400 rpm for 30 minutes. The mixture was then dried to obtain a soil conditioner.

[0064] Example 4: The difference from Example 1 is that the amount of sodium lignosulfonate composite material added is 30g.

[0065] Example 5: The difference from Example 1 is that the amount of sodium lignosulfonate composite material added is 40g.

[0066] Example 6: The difference from Example 1 is that the amount of chitosan / sodium lignosulfonate composite material added is 15g.

[0067] Example 7: The difference from Example 1 is that the amount of chitosan / sodium lignosulfonate composite material added is 25g.

[0068] Comparative Example 1: The difference from Example 1 is that sodium lignosulfonate composite material is not added.

[0069] Comparative Example 2: The difference from Example 1 is that the chitosan / sodium lignosulfonate composite material is not added.

[0070] Comparative Example 3: The difference from Example 1 is that the amount of sodium lignosulfonate composite material added is 29g.

[0071] Comparative Example 4: The difference from Example 1 is that the amount of sodium lignosulfonate composite material added is 41g.

[0072] Comparative Example 5: The difference from Example 1 is that the amount of chitosan / sodium lignosulfonate composite material added is 14g.

[0073] Comparative Example 6: The difference from Example 1 is that the amount of chitosan / sodium lignosulfonate composite material added is 26g.

[0074] Performance testing: 1. The effects of soil conditioners on the physical properties of coastal saline-alkali soils A soil column leaching simulation experiment was conducted to examine the effect of soil conditioner on the physical properties of coastal saline-alkali soil. The specific steps were as follows: The tested saline-alkali soil was weighed and mixed evenly with the soil conditioner prepared in the above examples and comparative examples (the soil conditioner and water were added to the tested saline-alkali soil at a weight ratio of 1:2500). The mixture was then added to the leaching column, and water was added to the soil column to bring the soil to 70% of its field capacity. After standing for 24 hours, the first leaching was carried out. Leaching was repeated every 5 days for a total of 4 leachings.

[0075] Table 1. Effects of soil conditioners on the physical properties of coastal saline-alkali soils deal with <![CDATA[Soil bulk density / (g / cm 3 )]]> Soil aggregates (%) original soil 1.35 6.83 Example 1 1.02 9.45 Example 2 1.15 9.15 Example 3 1.12 9.20 Example 4 1.10 9.28 Example 5 1.12 9.30 Example 6 1.07 9.35 Example 7 1.08 9.40 Comparative Example 1 1.32 7.62 Comparative Example 2 1.29 8.14 Comparative Example 3 1.20 8.35 Comparative Example 4 1.22 8.41 Comparative Example 5 1.19 8.90 Comparative Example 6 1.17 9.02 As shown in Table 1, compared with the original soil, the soil conditioners prepared using Examples 1-7 of this application can effectively reduce soil bulk density, increase soil aggregate content, and improve the quality of coastal saline-alkali soil.

[0076] Based on Example 1 and Comparative Example 1, it can be seen that the soil bulk density and soil aggregate content test results of Example 1 are better than those of Comparative Example 1, indicating that the addition of sodium lignosulfonate composite material can effectively reduce soil bulk density, increase soil aggregate content, and improve the quality of coastal salinized soil.

[0077] Based on Example 1 and Comparative Example 2, the soil bulk density and soil aggregate content test results of Example 1 are better than those of Comparative Example 2, indicating that the addition of chitosan / sodium lignosulfonate composite material can effectively reduce soil bulk density, increase soil aggregate content, and improve the quality of coastal salinized soil.

[0078] Based on the test results of Examples 1, 4, 5, Comparative Example 3, and Comparative Example 4, it can be seen that the amount of sodium lignosulfonate composite material added has a certain impact on the test results of soil bulk density and soil aggregate content. Furthermore, the optimal amount of sodium lignosulfonate composite material added is 30-40g, which results in the best soil bulk density and soil aggregate content.

[0079] Based on the test results of Examples 1, 6, 7, Comparative Example 5, and Comparative Example 6, it can be seen that the amount of chitosan / sodium lignosulfonate composite material added has a certain impact on the test results of soil bulk density and soil aggregate content. Furthermore, the optimal amount of chitosan / sodium lignosulfonate composite material added is 15-25g, which results in the best soil bulk density and soil aggregate content.

[0080] 2. The effects of soil conditioners on the chemical properties of coastal saline-alkali soils The soil conditioner prepared in the above examples and comparative examples was applied to the coastal saline-alkali soil at a weight ratio of 1:2500. The soil was plowed to a depth of 20 cm and thoroughly watered once. The soil was then kept for 30 days, with proper drainage during the process. After the specified time, the soil pH and soil sodium adsorption ratio (SAR) of the coastal saline-alkali soil were tested.

[0081] Table 2. Effects of soil conditioners on the chemical properties of coastal saline-alkali soils deal with Soil pH <![CDATA[Sodium adsorption ratio of soil / mmol / L 1 / 2 )]]> original soil 8.56 14.41 Example 1 7.01 0.06 Example 2 7.32 0.15 Example 3 7.35 0.18 Example 4 7.26 0.10 Example 5 7.28 0.11 Example 6 7.12 0.09 Example 7 7.15 0.08 Comparative Example 1 8.11 3.12 Comparative Example 2 8.02 2.88 Comparative Example 3 7.76 2.71 Comparative Example 4 7.73 2.70 Comparative Example 5 7.52 2.61 Comparative Example 6 7.51 2.63 As shown in Table 2, compared with the original soil, the soil conditioners prepared using Examples 1-7 of this application can reduce soil pH and reduce soil sodium adsorption ratio.

[0082] Based on the test results of Example 1 and Comparative Example 1, it can be seen that the soil pH and soil sodium adsorption ratio test results of Example 1 are better than those of Comparative Example 1, indicating that the addition of sodium lignosulfonate composite material can reduce soil pH and reduce soil sodium adsorption ratio.

[0083] Based on the test results of Example 1 and Comparative Example 2, it can be seen that the soil pH and soil sodium adsorption ratio test results of Example 1 are better than those of Comparative Example 2, indicating that the addition of chitosan / sodium lignosulfonate composite material can reduce soil pH and reduce soil sodium adsorption ratio.

[0084] Based on the test results of Examples 1, 4, 5, Comparative Example 3, and Comparative Example 4, it can be seen that the amount of sodium lignosulfonate composite material added has a certain impact on the test results of soil pH and soil sodium adsorption ratio. Furthermore, the soil pH and soil sodium adsorption ratio are optimal when the amount of sodium lignosulfonate composite material added is 30-40g.

[0085] Based on the test results of Examples 1, 6, 7, Comparative Example 5, and Comparative Example 6, it can be seen that the amount of chitosan / sodium lignosulfonate composite material added has a certain impact on the test results of soil pH and soil sodium adsorption ratio. Furthermore, the optimal soil pH and soil sodium adsorption ratio are achieved when the amount of chitosan / sodium lignosulfonate composite material added is 15-25g.

[0086] 3. The effect of soil conditioners on the biomass of rapeseed The soil conditioner prepared in the above examples and comparative examples was mixed with water at a weight ratio of 1:2500 in coastal saline-alkali soil. The mixture was thoroughly mixed, and potted for experimentation. The soil moisture content was maintained at 25% using a weighing method. After aging for 7 days, the soil was washed away of salt, and water was applied at 60% of its dry weight. After salt removal, the soil was dried for 3 days. Uniformly sized small rapeseed seeds were selected, and 10-20 seeds were sown in each pot. The seeds were evenly scattered on the soil surface and lightly covered with a thin layer of soil, 0.3-0.5 cm thick. Seedlings were thinned at the initial emergence stage, leaving 3 uniformly growing plants per pot. Harvesting was carried out 35 days after planting.

[0087] Table 3. Effects of soil conditioners on rapeseed biomass As shown in Table 3, compared with the treatment of adding only base fertilizer, the treatment of adding soil conditioner prepared in Examples 1-7 and base fertilizer can significantly increase the biomass of rapeseed planted in coastal saline-alkali soil.

Claims

1. A humic acid-based soil conditioner for coastal saline-alkali land, characterized in that: The raw material components include the following parts by weight: 40-60 parts cow manure, 10-30 parts vinegar residue, 25-45 parts compound humic acid slurry, 4-8 parts micronutrient fertilizer, 25-55 parts compound microorganisms, 8-14 parts desulfurized gypsum, and 30-40 parts sodium lignosulfonate composite material.

2. The humic acid soil conditioner for coastal saline-alkali land according to claim 1, characterized in that: The sodium lignosulfonate composite material comprises the following raw material components in parts by weight: 5-15 parts sodium lignosulfonate, 0.1-1 parts sodium hydroxide, 1-5 parts diethylenetriamine, 3.5-5.5 parts formaldehyde, 2-8 parts lignin, and 80-100 parts concentrated sulfuric acid.

3. A humic acid soil conditioner for coastal saline-alkali land according to claim 2, characterized in that: The preparation method of the sodium lignosulfonate composite material includes the following steps: Sodium lignosulfonate and sodium hydroxide were mixed, then diethylenetriamine was added and mixed again, followed by the addition of formaldehyde and the mixture was filtered to obtain the first mixture. The lignin and concentrated sulfuric acid were mixed and filtered to obtain a second mixture; The first mixture and the second mixture are mixed to obtain a sodium lignosulfonate composite material.

4. A humic acid soil conditioner for coastal saline-alkali land according to claim 2, characterized in that: The sodium lignosulfonate composite material also includes 15-25 parts by weight of chitosan / sodium lignosulfonate composite material.

5. A humic acid soil conditioner for coastal saline-alkali land according to claim 4, characterized in that: The chitosan / sodium lignosulfonate composite material comprises the following raw material components in parts by weight: 10-20 parts modified starch, 8-12 parts modified sodium lignosulfonate, and 0.02-0.2 parts chitosan hydrochloride.

6. A humic acid soil conditioner for coastal saline-alkali land according to claim 5, characterized in that: The modified starch comprises the following raw material components in parts by weight: 0.5-1.5 parts starch, 0.6-1.6 parts vinyltriethoxysilane, and 0.05-0.1 parts sodium methoxide.

7. A humic acid soil conditioner for coastal saline-alkali land according to claim 5, characterized in that: The modified sodium lignosulfonate comprises the following raw material components in parts by weight: 0.5-1.5 parts sodium lignosulfonate, 25-35 parts sodium hydroxide, and 10-14 parts chloroform.

8. A humic acid soil conditioner for coastal saline-alkali land according to any one of claims 4-7, characterized in that: The preparation method of the chitosan / sodium lignosulfonate composite material includes the following steps: Preparation of modified starch: Starch is gelatinized to obtain gelatinized starch; Gelatinized starch and vinyltriethoxysilane were mixed, and sodium methoxide was added and mixed to obtain modified starch. Preparation of modified sodium lignosulfonate: Sodium lignosulfonate and sodium hydroxide were mixed, and chloroform was added to obtain modified sodium lignosulfonate. Preparation of composite materials: Modified sodium lignosulfonate and chitosan hydrochloride were mixed, and then modified starch was added and mixed to obtain a chitosan / sodium lignosulfonate composite material.

9. A humic acid soil conditioner for coastal saline-alkali land according to claim 1, characterized in that: The composite microorganism comprises the following raw material components in parts by weight: 10-20 parts of Bacillus subtilis, 10-20 parts of Bacillus megaterium, and 5-15 parts of Azotobacter chrysotrichum.

10. A method for preparing a humic acid-based soil conditioner for coastal saline-alkali land, characterized in that, The preparation method comprises the following steps: Weigh out each ingredient according to the formula; A soil conditioner is obtained by mixing cow dung, vinegar residue, compound humic acid slurry, micronutrient fertilizer, compound microorganisms, desulfurized gypsum, and sodium lignosulfonate composite material, and then drying it.

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