Saline-alkali soil conditioner and preparation method thereof

Abstract

The invention relates to a saline-alkali soil conditioner and a preparation method thereof, and belongs to the technical field of environmental governance. The improver is formed by compounding a base fertilizer, a saline-alkali regulator and biological acid. Wherein the saline-alkali regulator is prepared by the following method: firstly, calcining oyster shells at low temperature to form porous powder, then synthesizing a diacrylate intermediate through esterification reaction, then reacting with a silane coupling agent to generate a modified coupling agent, and finally bridging the oyster shell powder through the coupling agent to form an organic-inorganic cluster structure. In the initial stage of the cluster structure, a porous microenvironment is constructed around a root system, soil hardening is broken, and salt ions are fixed through a chelation-adsorption dual mechanism; and the biodegradable organic chain segments are gradually hydrolyzed in the later stage, so that the clusters are disintegrated and immobilized salt is released to be absorbed by plants, and self-adaptive recovery and gradual desalination of the soil structure are realized. According to the invention, the organic combination of chemical rapid improvement and biological continuous repair is realized, the improvement effect is lasting, and the method is environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental governance, and in particular relates to a saline-alkali soil conditioner and a preparation method thereof. BACKGROUND

[0002] As a typical low-yield soil, the concentration of soluble salt in the soil solution of saline-alkali soil is significantly over-standard, forming a high-osmotic pressure environment, which seriously hinders the normal absorption of water by plant roots. At the same time, a large number of exchangeable sodium ions are adsorbed on the surface of soil colloids, causing the pH value of the soil to abnormally rise, usually reaching more than 8.5, and even exceeding 10.0 in severe cases. This strong alkaline environment can fix various essential nutrients such as phosphorus, iron, zinc and manganese in the soil, converting them into forms that are difficult for plants to utilize. More seriously, the dispersion of sodium ions can destroy the soil aggregate structure, causing soil microparticles to fill the pores, resulting in a "sticky and non-porous when wet, hard and easy to be compacted when dry" adverse physical state, significantly reducing the soil permeability and bringing great difficulties to cultivation.

[0003] The current mainstream saline-alkali soil improvement technology mainly includes chemical improvement method, organic improvement method and biological improvement method. The chemical improvement method adds gypsum, phosphogypsum and other calcium-containing substances to replace sodium ions on the surface of soil colloids with calcium ions, which can quickly reduce the soil pH value and alkalinity, but the dosage of the improvement agent is large, the cost is high, and the treated soil is not suitable for crop planting in the short term, which has potential environmental risks. The organic improvement method supplements soil organic matter by applying organic fertilizer, which can improve soil structure, but its improvement effect is significantly affected by soil water movement and is difficult to maintain long-term effectiveness under repeated migration of saline-alkali ions.

[0004] The biological improvement method uses the synergistic effect of salt-tolerant plants and microorganisms to achieve dynamic improvement of soil quality, which has the advantages of environmental friendliness and long-lasting effect. However, this method has obvious limitations: only a few salt-tolerant plants can grow normally in severe saline-alkali soil, which easily leads to soil nutrient imbalance and continuous cropping obstacles; at the same time, crops grow poorly under salt-alkali stress, significantly delaying the desalinization process, resulting in a long soil recovery period. There is an inherent conflict between existing chemical improvement agents and biological improvement methods: although chemical improvement agents can quickly improve soil physical and chemical properties, their strong chemical action often inhibits soil microbial activity and destroys the initial microecological environment; while pure biological improvement is hindered by plant growth under salt-alkali stress, making it difficult to form a virtuous cycle. This contradiction seriously restricts the large-scale promotion and application of saline-alkali soil improvement, and a new improvement technology that can synergize chemical rapid improvement and biological sustained repair is urgently needed. SUMMARY

[0005] In order to solve the technical problems mentioned in the background art, the purpose of the present application is to provide a saline-alkali soil conditioner and a preparation method thereof.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] A saline-alkali soil conditioner, the specific weight percentage components are: saline-alkali regulator 45-52wt%, biological acid 3.7-4.4wt%, and microbial inoculant 0.6-0.8wt%, and the balance is base fertilizer.

[0008] The saline-alkali regulator is prepared by the following method:

[0009] Step A1: tartaric acid, triethylamine, acetonitrile and tetrahydrofuran are mixed, an ice water bath is used for cooling, and under the protection of dry nitrogen, acryloyl chloride is slowly added to control the temperature not higher than 20 DEG C, stirring reaction for 3-4h, then heating to 60 DEG C reflux for 1-1.5h, after the reaction is finished, filtering and rotary evaporation to remove the solvent, to obtain the esterification intermediate;

[0010] Further, the amount ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile and tetrahydrofuran is 0.1mol: 0.21-0.22mol: 15-20mL: 80-100mL: 200-250mL, acryloyl chloride is esterified with tartaric acid, and the acrylate structure is introduced.

[0011] Step A2: the esterification intermediate, silane coupling agent KH-580 and ethyl acetate are mixed, a photoinitiator is added, and stirring reaction is carried out under ultraviolet irradiation for 6-8h, after the reaction is finished, rotary evaporation is carried out to remove the solvent, to obtain the modified coupling agent;

[0012] Further, the amount ratio of the esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol: 0.2mol: 0.17-0.22g: 420-480mL, the silane coupling agent KH-580 is subjected to thiol-ene click addition reaction with the esterification intermediate, and the triethoxysilane structure is introduced.

[0013] Step A3: the modified coupling agent and DMF aqueous solution are mixed, the mixture is acidified to pH 4-5, heated to 55-70 DEG C, then the calcined oyster shell powder is added and stirred for 2.5-3.5h, after neutralization, the precipitate is allowed to stand and washed with ethanol and water, and dried, to obtain the saline-alkali regulator;

[0014] Further, the amount ratio of the calcined oyster shell powder, the modified coupling agent and the DMF aqueous solution is 50g: 6.5-8.2g: 200-250mL, the double triethoxysilane structure of the modified coupling agent is fully hydrolyzed and coupled, so as to promote the mutual combination of oyster shell powder particles to form organic-inorganic cluster structure;

[0015] Further, the calcination temperature of the calcined oyster shell powder is 400-500 DEG C, the organic matter in the oyster shell is effectively removed, a large number of pore structures are formed, and the calcium carbonate matrix is maintained, and good stability is maintained in saline-alkali soil;

[0016] Further, the fineness of the calcined oyster shell powder is 20-50 mesh, under the fineness range, the cluster particle size formed by the agglomeration between the microparticles is moderate, and good pore air permeability can be formed in the saline-alkali soil, while maintaining certain water retention capacity, which is beneficial to the growth of plant roots.

[0017] Preferably, the biological acid is compounded by humic acid and plant-derived amino acid, which can effectively improve the initial alkaline environment and adjust the environment suitable for plant root growth.

[0018] Preferably, the base fertilizer is an organic fertilizer subjected to composting treatment, and the composted fertilizer has high fertilizer efficiency and loose state, which is suitable for the survival of primary planting crops.

[0019] A preparation method of a saline-alkali soil conditioner, specifically comprising: dispersing base fertilizer, adding biological acid and microbial inoculant for premixing, adding saline-alkali adjusting agent for mixing, and discharging to obtain the soil conditioner.

[0020] The beneficial effects of the present application are:

[0021] The saline-alkali soil conditioner provided by the present application realizes a self-adaptive improvement mechanism capable of dynamically responding to changes in soil environment, and this characteristic mainly benefits from the unique organic-inorganic composite structure of the saline-alkali adjusting agent and its behavior characteristics in the soil over time, specifically:

[0022] The microstructure construction of the saline-alkali adjusting agent starts from its special preparation process, through low-temperature calcination of oyster shells, the pyrolysis of organic matter is realized while the basic skeleton of calcium carbonate is reserved, and a porous material with rich internal pores is formed. This porous structure not only provides a large specific surface area, but also lays a foundation for subsequent microstructure assembly. The key structural breakthrough comes from the modified coupling agent synthesized by molecular design, which is a double acrylate intermediate constructed by acryloyl chloride and tartaric acid, and then grafted with KH-580 silane coupling agent through thiol-ene click chemistry reaction, and finally forms a structure bridging molecule with double triethoxysilane functional groups.

[0023] When this modified coupling agent encounters porous oyster shell powder in a liquid environment, its terminal triethoxysilyl groups hydrolyze into silanol groups under mild acidic conditions. These silanol groups form strong covalent bonds with the hydroxyl groups on the oyster shell surface and also condense with the silanol groups of other coupling agent molecules, thereby constructing a stable three-dimensional network structure between oyster shell particles. This organic-inorganic cluster formed through molecular bridging has the following unique advantages: First, the inherent nanoscale pores of oyster shell powder are retained within the cluster, while a micron-scale mesoporous structure is formed between the particles. This hierarchical pore system provides an ideal channel for salt ion adsorption and water transport; second, the tartaric acid-derived organic segments endow the cluster structure with moderate flexibility and biodegradability.

[0024] In the initial stage of soil amendment application, these cluster structures form numerous stable microporous domains around plant roots, effectively breaking down the dense structure of saline-alkali soil and creating a physical environment conducive to root growth. Simultaneously, the carboxyl functional groups carried by the tartaric acid-derived structures within the clusters exhibit excellent chelating capabilities, selectively binding to sodium ions adsorbed on soil colloids. This disrupts the dispersion of soil particles caused by sodium ions, promoting the reconstruction of soil aggregate structure. The chelated sodium ions are subsequently captured and fixed by the porous structure of oyster shells, forming a dual salt-fixing mechanism of chemical chelation and physical adsorption, rapidly reducing salt stress in the root zone.

[0025] As the crop growth cycle progresses, the adaptive properties of soil conditioners begin to emerge. Under the combined action of soil microorganisms and root exudates, tartaric acid-derived segments gradually degrade. This degradation process exhibits a clear time-response characteristic: maintaining structural integrity during soil improvement provides a stable root environment for plants, allowing mature plants to absorb and transfer salts to the aboveground parts, ultimately achieving permanent removal of salts through harvesting. In the later stages of soil remediation, the gradual disintegration of the cluster structure not only achieves the controlled release of retained salts but also avoids soil structural disturbances that may be caused by traditional conditioners, truly realizing the synergistic advancement of improvement, fertilization, and ecological restoration. This adaptive improvement mechanism ensures a dynamic alignment between the improvement effect and the plant's growth needs, providing a novel technological path for the sustainable management of saline-alkali land. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: Preparation of a soil conditioner for saline-alkali land. The specific implementation method is as follows:

[0028] I. Preparation of Salt-Alkali Regulator

[0029] 1. Take oyster shells as processing waste, remove surface algae and adhering substances, dry and crush them, then place them in a muffle furnace and roast them at a low temperature of 400℃ for 7 hours. After cooling, grind and pulverize them. The pulverized material is sieved through 20-mesh and 50-mesh sieves in sequence, and the fine powder with a fineness of 20-50 mesh is taken to obtain roasted oyster shell powder.

[0030] 2. Tartaric acid, triethylamine, acetonitrile, and tetrahydrofuran were added and stirred together. The mixture was cooled to below 5°C using an ice-water bath and protected with nitrogen. Acryloyl chloride was slowly added, and the addition rate was controlled to keep the reaction system temperature below 20°C. The reaction was stirred for a total of 3 hours. After that, the reaction system was heated to 60°C and refluxed for 1.5 hours. The ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile, and tetrahydrofuran was 0.1 mol: 0.22 mol: 20 mL: 100 mL: 200 mL. After the reaction was completed, the salts were removed by filtration, and the solvents acetonitrile and tetrahydrofuran were removed by rotary evaporation to obtain the esterification intermediate.

[0031] 3. Take the esterification intermediate, silane coupling agent KH-580 and ethyl acetate, add them to the mixture and stir. Add the photoinitiator (PI-1173) and mix again. Irradiate with a 500W 365nm ultraviolet mercury lamp and stir for 6 hours. The ratio of esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol:0.2mol:0.22g:480mL. After the reaction is completed, rotary evaporate the solvent ethyl acetate to obtain the modified coupling agent.

[0032] 4. Mix the modified coupling agent and DMF aqueous solution (volume fraction 45%), add formic acid to acidify the mixture until the pH value is 4, heat to 70℃, and then add the roasted oyster shell powder prepared above and stir for coupling for 2.5h. The ratio of roasted oyster shell powder, modified coupling agent and DMF aqueous solution is 50g:8.2g:250mL. Finally, neutralize with ammonia water and let stand to precipitate. Take the precipitate, wash with ethanol and water and dry to obtain the salt-alkali regulator.

[0033] II. Preparation of Soil Conditioner

[0034] The ingredients are prepared according to the following weight percentages: 45 wt% salt-alkali regulator, which is self-made in this embodiment; 4.4 wt% bio-acid, which is a compound of humic acid and plant-derived amino acids in a weight ratio of 2:1; 0.6 wt% microbial agent, a commercially available compound preparation; and the remainder is base fertilizer, which is well-rotted cow manure and corn stalks.

[0035] Add the base fertilizer to the mixer and stir at 60 rpm to break it up into a loose state. Then add bio-acid and microbial agent for premixing, and then add salt and alkali regulator and mix well. The discharged material is the soil conditioner.

[0036] Example 2: Preparation of a soil conditioner for saline-alkali land. The specific implementation method is as follows:

[0037] I. Preparation of Salt-Alkali Regulator

[0038] 1. Take oyster shells as processing waste, remove surface algae and adhering substances, dry and crush them, then place them in a muffle furnace and roast them at a low temperature of 500℃ for 6 hours. After cooling, grind and pulverize them. The pulverized material is sieved through 20-mesh and 50-mesh sieves in sequence, and the fine powder with a fineness of 20-50 mesh is taken to obtain roasted oyster shell powder.

[0039] 2. Tartaric acid, triethylamine, acetonitrile, and tetrahydrofuran were added and stirred. The mixture was cooled to below 5°C using an ice-water bath and protected with nitrogen. Acryloyl chloride was slowly added, and the addition rate was controlled to keep the reaction system temperature below 20°C. The reaction was stirred for a total of 4 hours. After that, the reaction system was heated to 60°C and refluxed for 1 hour. The ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile, and tetrahydrofuran was 0.1 mol: 0.21 mol: 15 mL: 80 mL: 250 mL. After the reaction was completed, the salts were removed by filtration, and the solvents acetonitrile and tetrahydrofuran were removed by rotary evaporation to obtain the esterification intermediate.

[0040] 3. Take the esterification intermediate, silane coupling agent KH-580 and ethyl acetate, add them and stir to mix. Add the photoinitiator (PI-1173) and mix again. Irradiate with a 500W 365nm ultraviolet mercury lamp and stir for 8 hours. The ratio of esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol:0.2mol:0.17g:420mL. After the reaction is completed, rotary evaporate the solvent ethyl acetate to obtain the modified coupling agent.

[0041] 4. Mix the modified coupling agent and DMF aqueous solution (volume fraction 45%), add formic acid to acidify the mixture until the pH value is 5, raise the temperature to 55℃, and then add the roasted oyster shell powder prepared above and stir for coupling for 3.5h. The ratio of roasted oyster shell powder, modified coupling agent and DMF aqueous solution is 50g:6.5g:200mL. Finally, neutralize with ammonia water and let it stand to precipitate. Take the precipitate, wash it with ethanol and water and dry it to obtain the salt-alkali regulator.

[0042] II. Preparation of Soil Conditioner

[0043] The ingredients are prepared according to the following weight percentages: 52 wt% salt-alkali regulator, which is self-made in this embodiment; 3.7 wt% bio-acid, which is a compound of humic acid and plant-derived amino acids in a weight ratio of 2:1; 0.8 wt% microbial agent, a commercially available compound preparation; and the remainder is base fertilizer, which is well-rotted cow manure and corn stalks.

[0044] Add the base fertilizer to the mixer and stir at 60 rpm to break it up into a loose state. Then add bio-acid and microbial agent for premixing, and then add salt and alkali regulator and mix well. The discharged material is the soil conditioner.

[0045] Example 3: Preparation of a soil conditioner for saline-alkali land. The specific implementation method is as follows:

[0046] I. Preparation of Salt-Alkali Regulator

[0047] 1. Take oyster shells as processing waste, remove surface algae and adhering substances, dry and crush them, then place them in a muffle furnace and roast them at a low temperature of 450℃ for 7 hours. After cooling, grind and pulverize them. The pulverized material is sieved through 20-mesh and 50-mesh sieves in sequence, and the fine powder with a fineness of 20-50 mesh is taken to obtain roasted oyster shell powder.

[0048] 2. Tartaric acid, triethylamine, acetonitrile, and tetrahydrofuran were added and stirred. The mixture was cooled to below 5°C using an ice-water bath, and nitrogen gas was introduced for protection. Acryloyl chloride was slowly added, and the addition rate was controlled to keep the temperature of the reaction system below 20°C. The reaction was stirred for a total of 3.5 hours. After that, the reaction system was heated to 60°C and refluxed for 1.2 hours. The ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile, and tetrahydrofuran was 0.1 mol: 0.22 mol: 15 mL: 100 mL: 200 mL. After the reaction was completed, the salt was removed by filtration, and the solvents acetonitrile and tetrahydrofuran were removed by rotary evaporation to obtain the esterification intermediate.

[0049] 3. Take the esterification intermediate, silane coupling agent KH-580 and ethyl acetate, add them and stir to mix. Add the photoinitiator (PI-1173) and mix again. Irradiate with a 500W 365nm ultraviolet mercury lamp and stir for 7.5h. The ratio of esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol:0.2mol:0.19g:450mL. After the reaction is completed, rotary evaporate the solvent ethyl acetate to obtain the modified coupling agent.

[0050] 4. Mix the modified coupling agent and DMF aqueous solution (volume fraction 45%), add formic acid to acidify the mixture until the pH value is 4, heat to 60℃, and then add the roasted oyster shell powder prepared above and stir for coupling for 3 hours. The ratio of roasted oyster shell powder, modified coupling agent and DMF aqueous solution is 50g:7.5g:230mL. Finally, neutralize with ammonia water and let stand to precipitate. Take the precipitate, wash with ethanol and water and dry to obtain the salt-alkali regulator.

[0051] II. Preparation of Soil Conditioner

[0052] The ingredients are prepared according to the following weight percentages: 50 wt% salt-alkali regulator, which is self-made in this embodiment; 4.1 wt% bio-acid, which is a compound of humic acid and plant-derived amino acids in a weight ratio of 2:1; 0.7 wt% microbial agent, a commercially available compound preparation; and the remainder is base fertilizer, which is well-rotted cow manure and corn stalks.

[0053] Add the base fertilizer to the mixer and stir at 60 rpm to break it up into a loose state. Then add bio-acid and microbial agent for premixing, and then add salt and alkali regulator and mix well. The discharged material is the soil conditioner.

[0054] Example 4: Preparation of a soil conditioner for saline-alkali land. The specific implementation method is as follows:

[0055] I. Preparation of Salt-Alkali Regulator

[0056] 1. Take oyster shells as processing waste, remove surface algae and adhering substances, dry and crush them, then place them in a muffle furnace and roast them at a low temperature of 500℃ for 6.5 hours. After cooling, grind and pulverize them. The pulverized material is sieved through 20-mesh and 50-mesh sieves in sequence, and the fine powder with a fineness of 20-50 mesh is retained to obtain roasted oyster shell powder.

[0057] 2. Tartaric acid, triethylamine, acetonitrile, and tetrahydrofuran were added and stirred together. The mixture was cooled to below 5°C using an ice-water bath, and nitrogen gas was introduced for protection. Acryloyl chloride was slowly added, and the addition rate was controlled to keep the temperature of the reaction system below 20°C. The reaction was stirred for a total of 4 hours. After that, the reaction system was heated to 60°C and refluxed for 1.2 hours. The ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile, and tetrahydrofuran was 0.1 mol: 0.21 mol: 17 mL: 90 mL: 230 mL. After the reaction was completed, the salt was removed by filtration, and the solvents acetonitrile and tetrahydrofuran were removed by rotary evaporation to obtain the esterification intermediate.

[0058] 3. Take the esterification intermediate, silane coupling agent KH-580 and ethyl acetate, add them and stir to mix. Add the photoinitiator (PI-1173) and mix again. Irradiate with a 500W 365nm ultraviolet mercury lamp and stir for 7 hours. The ratio of esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol:0.2mol:0.2g:460mL. After the reaction is completed, rotary evaporate the solvent ethyl acetate to obtain the modified coupling agent.

[0059] 4. Mix the modified coupling agent and DMF aqueous solution (volume fraction 45%), add formic acid to acidify the mixture until the pH value is 4, heat to 65℃, and then add the roasted oyster shell powder prepared above and stir for coupling for 3.2h. The ratio of roasted oyster shell powder, modified coupling agent and DMF aqueous solution is 50g:7g:220mL. Finally, neutralize with ammonia water and let stand to precipitate. Take the precipitate, wash with ethanol and water and dry to obtain the salt-alkali regulator.

[0060] II. Preparation of Soil Conditioner

[0061] The ingredients are prepared according to the following weight percentages: 48 wt% salt-alkali regulator, which is self-made in this embodiment; 4 wt% bio-acid, which is a compound of humic acid and plant-derived amino acids in a weight ratio of 2:1; 0.8 wt% microbial agent, a commercially available compound preparation; and the remainder is base fertilizer, which is well-rotted cow manure and corn stalks.

[0062] Add the base fertilizer to the mixer and stir at 60 rpm to break it up into a loose state. Then add bio-acid and microbial agent for premixing, and then add salt and alkali regulator and mix well. The discharged material is the soil conditioner.

[0063] Comparative Example 1 follows the same implementation method as Example 4, but without adding a salt-alkali regulator, and instead using an equal amount of base fertilizer. The rest of the implementation process is exactly the same.

[0064] Comparative Example 2: A soil conditioner was prepared according to existing technology. Its specific components are: 24 wt% phosphogypsum, 6.5 wt% wood ash, 12 wt% bamboo charcoal powder, 4 wt% bio-acid, and 0.8 wt% microbial inoculant, with the remainder being base fertilizer.

[0065] To verify the soil amendment effect, a biological method was used to conduct a desalination and alkalization test, specifically:

[0066] The tested soil was collected from the 0-20cm topsoil layer of the coastal saline-alkali land in Jiangsu Province. Its initial physicochemical properties were: pH 8.9, electrical conductivity 3.8 mS / cm, total salt content 0.53%, porosity 32%, and organic matter content 6.5 g / kg.

[0067] The tested crops were Suaeda salsa, Tamarix chinensis, Sesbania sesquiterpene, and Lespedeza bicolor.

[0068] Cultivation and Management: Plastic pot experiments were conducted, with each pot containing 5 kg of soil. For the first planting, soil conditioner was applied at 50 g / plant at the root system. The plants were then placed in a greenhouse for cultivation (day / night temperature 25 / 18℃, light 12h / d). Each season's crops were harvested at ground level after 60 days of growth. Four types of crops were rotated simultaneously.

[0069] Improvement index testing: Plant fresh weight: after harvesting at ground level, the plants were weighed, and the highest and lowest values ​​were removed to calculate the average fresh weight; Soil electrical conductivity: the soil after crop rotation was mixed and extracted at a soil-to-water ratio of 1:5, and the conductivity was measured using a conductivity meter; Soil total salt content: determined by gravimetric method as above; Soil pH: at a soil-to-water ratio of 1:2.5, the pH was measured using a pH meter; Specific test results are shown in Table 1:

[0070] Table 1

[0071]

[0072] As can be seen from the test results in Table 1, in the cultivation experiment, the experimental group with soil conditioner prepared in the example showed more vigorous crop growth, and the average fresh weight of a single plant was significantly better than that of the control group. Furthermore, after crop rotation, the soil electrical conductivity and total salt content decreased significantly, and the soil pH also decreased significantly, gradually approaching the suitable planting range, effectively repairing and improving saline-alkali land.

[0073] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A soil conditioner for saline-alkali land, characterized in that, The specific weight percentage composition is as follows: 45-52 wt% salt-alkali regulator, 3.7-4.4 wt% bio-acid, and 0.6-0.8 wt% microbial inoculant, with the remainder being base fertilizer; The salt-alkali regulator is prepared by the following method: Step A1: Mix tartaric acid, triethylamine, acetonitrile and tetrahydrofuran, cool in an ice-water bath and slowly add acryloyl chloride under dry nitrogen protection, stirring for 3-4 hours while controlling the temperature not to exceed 20°C. Then heat to 60°C and reflux for 1-1.5 hours to prepare the esterification intermediate. Step A2: Mix the esterification intermediate, silane coupling agent KH-580 and ethyl acetate, add the photoinitiator and stir under ultraviolet irradiation for 6-8 hours to prepare the modified coupling agent; Step A3: Mix the modified coupling agent and DMF aqueous solution, acidify the mixture to pH 4-5, heat to 55-70℃, add roasted oyster shell powder and stir for 2.5-3.5 hours to prepare a salt-alkali regulator.

2. The soil conditioner for saline-alkali land according to claim 1, characterized in that, The ratio of tartaric acid, acryloyl chloride, triethylamine, acetonitrile, and tetrahydrofuran is 0.1 mol: 0.21-0.22 mol: 15-20 mL: 80-100 mL: 200-250 mL.

3. The soil conditioner for saline-alkali land according to claim 2, characterized in that, The ratio of esterification intermediate, silane coupling agent KH-580, photoinitiator and ethyl acetate is 0.1mol:0.2mol:0.17-0.22g:420-480mL.

4. The soil conditioner for saline-alkali land according to claim 3, characterized in that, The ratio of roasted oyster shell powder, modified coupling agent and DMF aqueous solution is 50g: 6.5-8.2g: 200-250mL.

5. A soil conditioner for saline-alkali land according to claim 4, characterized in that, The roasting temperature for oyster shell powder is 400-500℃.

6. A soil conditioner for saline-alkali land according to claim 5, characterized in that, The fineness of roasted oyster shell powder is 20-50 mesh.

7. The soil conditioner for saline-alkali land according to claim 1, characterized in that, Bioacids are composed of humic acid and plant-derived amino acids.

8. The soil conditioner for saline-alkali land according to claim 1, characterized in that, The base fertilizer is well-rotted organic fertilizer.

9. A method for preparing a saline-alkali soil conditioner according to any one of claims 1-8, characterized in that, Specifically, the process involves: breaking up the base fertilizer, adding bio-acid and microbial inoculant for premixing, then adding a salt-alkali regulator and mixing thoroughly. The resulting product is a soil conditioner.

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