Formulations and methods for improving saline soils with a water soluble eutectic mixture-acid synergistic amendment

Abstract

The present application relates to a kind of water-soluble eutectic mixture-acid synergistic improvement saline-alkali soil preparation and method, the preparation is composed of water-soluble eutectic mixture and acidic modifier;Wherein: the water-soluble eutectic mixture is mixed by first functional component (A) and second functional component (B) according to 1:1 to 1:10 molar ratio, is formed into low eutectic system by heating stirring or ultrasonic treatment in the temperature range of 25-80 DEG C;The addition amount of the acidic modifier is 0.1% to 10% of the mass of the eutectic mixture.The preparation is applied to saline-alkali soil by precision drip irrigation at 0.5wt%~10wt% concentration, can significantly reduce soil pH value and conductivity (EC) in short term, and improve soil structure and microbial activity by replacement and exclusion excess sodium ion.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a formulation and method for synergistically improving saline-alkali soil with water-soluble deep eutectic solvents (DESs) and acids. Background Technology

[0002] Soil salinization has become a major bottleneck for sustainable agricultural development globally. The accumulation of large amounts of soluble salts and alkaline substances severely damages soil structure, inhibits crop root growth, leads to a rapid decline in soil fertility, and further causes a series of problems such as reduced food production, water shortages, and ecological imbalance. The area of ​​saline-alkali land globally is continuously expanding, posing a serious challenge to food security and ecosystems.

[0003] Common methods for improving saline-alkali soil include:

[0004] Physical improvement methods, such as deep tillage, topsoil application, and irrigation to wash away salt, can reduce salinity to some extent, but they involve large-scale projects, long cycles, and are prone to causing secondary damage to soil structure or subsequent salinity rebound.

[0005] Chemical amendments, such as the application of gypsum or acidic substances, are relatively simple to implement but require large quantities and can easily cause soil compaction or secondary pollution.

[0006] Biological improvement, such as planting salt-tolerant plants and applying microbial agents, is environmentally friendly, but it is slow to take effect and is limited by geography and crop type, making it difficult to promote on a large scale.

[0007] Furthermore, recent studies have found that eutectic solvents (DESs) can play a role in heavy metal remediation and soil structure improvement due to their readily available raw materials, designability, low toxicity, and biodegradability. However, when faced with saline-alkali soils with high salinity and alkalinity, DESs alone often fail to quickly neutralize soil alkalinity or effectively replace sodium ions; while acidic amendments alone, although able to lower pH, can cause negative effects such as localized severe acidification or microbial ecological imbalance, making it difficult to balance alkalinity reduction efficiency with soil ecological safety. Summary of the Invention

[0008] This invention primarily addresses the problems of insufficient efficiency and high environmental risk encountered in the improvement of high-salt and high-alkali soils. It provides a synergistic soil amendment formulation that integrates a water-soluble eutectic mixture (DESs) with an acidic amendment, applied using precision drip irrigation technology. This formulation can significantly reduce soil pH and electrical conductivity (EC) in a short period, optimizing soil structure and water and fertilizer retention capacity. Preferably, by first preparing a water-soluble eutectic mixture with specific functional components, and then adding an acid to this mixture, a stable, transparent, and sustainably effective soil amendment formulation is obtained.

[0009] This invention first provides a formulation for the synergistic modification of saline-alkali soil using a water-soluble eutectic mixture and an acid modifier, wherein the formulation comprises a water-soluble eutectic mixture and an acid modifier; wherein:

[0010] The water-soluble eutectic mixture is formed by mixing a first functional component (A) and a second functional component (B) in a molar ratio of 1:1 to 1:10 and then heating and stirring or ultrasonically treating the mixture within a temperature range of 25°C to 80°C.

[0011] The amount of the acid modifier added is 0.1% to 10% of the mass of the eutectic mixture;

[0012] The first functional component (A) is selected from one or more of the following: choline chloride, betaine, proline, lysine, arginine or glycine betaine; the second functional component (B) is selected from one or more of the following: glycerol, ethylene glycol, propylene glycol, lactic acid, malic acid, citric acid, tartaric acid, succinic acid, glucose, fructose, sucrose, xylose, sorbitol, urea or acetamide.

[0013] Preferably, the molar ratio of the first functional component (A) to the second functional component (B) is 1:2 to 1:8, and the mixture is stirred or sonicated at a temperature of 40°C to 70°C for 1 to 3 hours to obtain a eutectic mixture.

[0014] Preferably, the acid modifier is selected from one or more of the following: hydrochloric acid, sulfuric acid, nitric acid, acetic acid, citric acid, lactic acid, malic acid, tartaric acid, succinic acid, formic acid, acetic acid, propionic acid, or butyric acid.

[0015] Preferably, the first functional component (A) is choline chloride or betaine, and the second functional component (B) is glycerol, ethylene glycol, propylene glycol, lactic acid, malic acid, citric acid, tartaric acid, or succinic acid; and the following selections are made according to the different types of saline-alkali soil:

[0016] For highly alkaline soils (pH≥9.0), (A) is selected from choline chloride or betaine, and (B) is selected from lactic acid, malic acid, citric acid, tartaric acid, succinic acid or a combination thereof;

[0017] For medium- to high-salinity soils (EC ≥ 5 dS / m), (A) is selected from choline chloride or betaine, and (B) is selected from glycerol, ethylene glycol, propylene glycol or a combination thereof.

[0018] Preferably, in order to enhance the synergistic effect between the eutectic mixture and the acidic amendment, the molar ratio of the first functional component (A) to the second functional component (B) can be further limited to 1:3-4, so as to obtain a more significant "1+1>2" gain effect in strongly saline-alkali soils.

[0019] The present invention also provides a method for the synergistic improvement of saline-alkali soil by a water-soluble eutectic mixture and an acid, characterized by comprising the following steps:

[0020] 1) Preparation of eutectic mixture: The first functional component (A) and the second functional component (B) are mixed in a molar ratio of 1:1 to 1:10 and heated and stirred or sonicated in the range of 25°C to 80°C until a uniform, transparent and stable water-soluble eutectic mixture is formed.

[0021] 2) Selection of acidic soil conditioners: Based on the type of saline-alkali soil, pH value, salt composition and crop tolerance, inorganic or organic acids are selected as acidic soil conditioners.

[0022] 3) Preparation of a water-soluble eutectic mixture-acid synergistic improvement agent for saline-alkali soil: The acid modifier selected in step (2) is added to the eutectic mixture prepared in step (1) at a ratio of 0.1% to 10% of the mass of the eutectic mixture and stirred evenly to obtain a water-soluble eutectic mixture-acid synergistic improvement agent for saline-alkali soil.

[0023] 4) Dilution: Dilute the preparation with irrigation water to a concentration of 0.5 wt% to 10 wt%;

[0024] 5) Precision drip irrigation application: Apply the diluted preparation from step (4) to the saline-alkali soil by drip irrigation. The application rate is 0.1 kg to 5 kg per square meter of saline-alkali soil. The drip irrigation frequency is 1 to 3 times per week, and the drip irrigation time is 1 to 4 hours each time.

[0025] Preferably, in step (3), the amount of acid modifier added is 0.5% to 5% of the mass of the eutectic mixture, and the dilution concentration of the modifier is 1 wt% to 5 wt%.

[0026] Preferably, the dosage of the formulation in a single application during drip irrigation is 0.5 kg to 3 kg per square meter; and it is applied in multiple drip irrigations over 2 to 4 consecutive weeks during the main growth stage of the crop to achieve rapid pH reduction and stable improvement.

[0027] Preferably, the combination of the first functional component (A) and the second functional component (B) follows the following principles:

[0028] For highly alkaline saline-alkali soils: use lactic acid, malic acid, citric acid, tartaric acid, succinic acid or a combination thereof as the second functional component (B);

[0029] For high-salinity saline-alkali soils: use glycerol, ethylene glycol, propylene glycol or a combination thereof as the second functional component (B);

[0030] Based on soil structure and crop requirements, either choline chloride or betaine can be selected as the first functional component (A).

[0031] Preferably, soil pH, electrical conductivity (EC), and crop growth indicators are monitored simultaneously during drip irrigation to dynamically adjust the drip irrigation frequency or the concentration of the improver, ensuring a rapid and stable improvement effect without causing excessive soil acidification.

[0032] Beneficial effects

[0033] 1. Improve efficiency and speed

[0034] Data shows that the synergistic combination of "DESs + acid" improves the pH and EC reduction effects by 10% to 30% compared with acid or DESs alone, and significantly shortens the improvement cycle.

[0035] 2. Cost and Environmental Benefits

[0036] Compared to traditional single-acid methods, the total amount of acid used is significantly reduced; the preparation process is relatively simple and the raw materials are readily available; the overall improvement process is more economical and environmentally friendly.

[0037] 3. Durability and Ecological Security

[0038] While lowering pH, it can maintain or improve soil microbial activity, significantly reducing the risk of secondary salinization; crop yield and quality are also improved accordingly. Attached Figure Description

[0039] Figure 1 Example 3: Effects of different treatments on crop yield and protein content. Detailed Implementation

[0040] Test methods and standards:

[0041] Soil electrical conductivity (EC): Refer to NY / T 1377—2007;

[0042] pH and ESP: Refer to NY / T 1377 series standards;

[0043] Crop growth indicators, such as plant height, yield, and protein content, are measured and statistically analyzed according to standardized procedures during critical growth stages of the crop.

[0044] Example 1: Synergistic improvement of saline-alkali soil with choline chloride-glycerol eutectic mixture (water-soluble DESs) and citric acid.

[0045] This embodiment mainly targets moderately saline-alkali soil with pH≈8.5 and EC≈5.0dS / m, and verifies the synergistic effect of the combination of "choline chloride-glycerol" type DESs and citric acid through a control experiment.

[0046] 1) Preparation of water-soluble eutectic mixtures of choline chloride and glycerol (water-soluble DESs)

[0047] Choline chloride (first functional component) and glycerol (second functional component) were mixed at a molar ratio of 1:5; the mixture was stirred at a constant temperature of 60°C for 2 hours to obtain a homogeneous, transparent, and stable eutectic mixture of water-soluble choline chloride and glycerol.

[0048] 2) Preparation of a formulation for the synergistic improvement of saline-alkali soil by water-soluble eutectic mixtures and acids.

[0049] Take the prepared choline chloride-glycerol water-soluble eutectic mixture and add citric acid at 5% of its mass; stir at room temperature for about 0.3 hours to ensure that the citric acid dissolves and fully complexes with the water-soluble eutectic mixture to obtain a formulation for the synergistic improvement of saline-alkali soil by the water-soluble eutectic mixture-acid.

[0050] 3) Application of the formulation and drip irrigation parameters

[0051] The water-soluble eutectic mixture-acid synergistic improvement agent for saline-alkali soil prepared in step 2) is diluted with deionized water to 2% (mass percentage) to obtain a diluted solution. The diluted solution is then applied evenly to moderately saline-alkali soil using a precise drip irrigation method. Application rate: 1 kg / m² 2 Drip irrigation was performed twice a week for two hours each time, for eight weeks. Five samples were collected from each group, and soil indices were measured at weeks 0, 2, 4, and 8.

[0052] 4) Controlled experimental design

[0053] Control group (CK): No amendments were applied; the same mass of deionized water as in step 3) was used for drip irrigation at a rate of 1 kg / m². 2 Drip irrigation was applied twice a week for two hours each time, for eight weeks; soil samples were taken and measured at weeks 0, 2, 4, and 8.

[0054] DESs alone (DESs): Dilute the choline chloride-glycerol water-soluble eutectic mixture obtained in step 1) with an equal mass of deionized water obtained in step 3) to obtain a diluted solution; apply the diluted solution evenly to moderately saline-alkali soil using a precise drip irrigation method; application rate: 1 kg / m² 2 Drip irrigation was applied twice a week for two hours each time, for eight weeks. Soil samples were taken and measured in weeks 1, 2, 4, and 8.

[0055] Acid-only application: Take an equal mass of citric acid from step 2) and an equal mass of deionized water from step 3) to dilute the citric acid, obtaining a diluted solution; apply the diluted solution evenly to moderately saline-alkali soil using a precise drip irrigation method; application rate: 1 kg / m² 2 Drip irrigation was applied twice a week for two hours each time, for eight weeks; soil samples were taken and measured at weeks 0, 2, 4, and 8.

[0056] Collaboration group: The scheme of this embodiment 1.

[0057] 5) Soil physicochemical index testing

[0058] The following parameters were measured: pH, electrical conductivity (EC), exchangeable sodium percentage (ESP), cation exchange capacity (CEC), and organic matter (only the synergistic group and DES group were measured) of the soil sampled in step 3 above, as shown in Table 1.

[0059] Table 1. Effects of different treatments on soil pH, EC, ESP, and CEC (Example 1 and control group)

[0060]

[0061] illustrate:

[0062] I. Control group (CK), acid-only group, DESs-only group, and synergy group.

[0063] II. SE represents standard error.

[0064] III. As can be seen from the table above, the synergistic group showed the greatest decrease in pH and EC within 2 to 8 weeks, and the reduction in ESP and the increase in CEC were also significantly better than those using acid alone or DESs alone.

[0065] 6) Crop growth status and yield

[0066] Wheat was selected as the experimental crop and planted in moderately saline-alkali soil with pH≈8.5 and EC≈5.0dS / m as described in this embodiment. The control group (no application), the DESs-only group, the acid-only group, and the synergistic group were irrigated by drip irrigation in the manner described in step 4 above. Other management (such as fertilization) was also the same.

[0067] Plant height, tiller number, chlorophyll content (SPAD value), final biomass, grain protein content and yield were measured in week 8; as shown in Table 5.

[0068] Table 2. Wheat growth status and yield test data (Example 1 and control group)

[0069]

[0070] Comparative Example 1

[0071] 1. Preparation of water-soluble choline chloride-glycerol + citric acid preparation

[0072] Choline chloride (first functional component), glycerol (second functional component), and citric acid were mixed together in the proportions of Example 1 and stirred at a constant temperature of 60°C for 2 hours. Then, the mixture was cooled to room temperature and stirred for about 0.3 hours. The results showed that the eutectic network was not easy to form and there was local phase separation.

[0073] The preparation was diluted to 2% (mass percentage) with the same mass of deionized water as in step 3 of Example 1 to obtain a diluted solution. The diluted solution was then used to drip irrigate the soil of the same plot in Example 1. Wheat was selected as the test crop. Plant height, tiller number, chlorophyll content (SPAD value), final biomass, grain protein content and yield were measured in the 8th week. Five samples were measured, as shown in Table 3.

[0074] Table 3. Wheat growth status and yield test data (Example 1 and Comparative Example 1)

[0075]

[0076] Example 2: Synergistic improvement of saline-alkali soil by choline chloride-lactic acid eutectic mixture (DESs) and hydrochloric acid.

[0077] 1) Preparation of choline chloride-lactic acid eutectic mixture (DESs)

[0078] Choline chloride (first functional component) and lactic acid (second functional component) were mixed in a molar ratio of 1:3; the mixture was then sonicated at 50°C for about 1.5 hours until a homogeneous, transparent and stable eutectic mixture of choline chloride and lactic acid was formed.

[0079] 2) Preparation of a formulation for the synergistic improvement of saline-alkali soil by water-soluble eutectic mixtures and acids.

[0080] Hydrochloric acid (concentration 35wt%) was slowly added dropwise at 1% of the mass of the choline chloride-lactic acid mixture, and stirred at room temperature for 0.2 hours to obtain a stable water-soluble eutectic mixture-acid synergistic improvement of saline-alkali soil preparation, namely "DESs-hydrochloric acid" compound preparation.

[0081] 3) Application of the formulation and drip irrigation parameters

[0082] The water-soluble eutectic mixture-acid synergistic improvement agent for saline-alkali soil prepared in step 2) is diluted with deionized water to 1% (mass percentage) to obtain a diluted solution; it is applied to the saline-alkali soil by precision drip irrigation at a rate of 0.5 kg per square meter; the drip irrigation frequency is once a week for 3 hours each time, and the experimental period is recommended to be maintained for 6 to 8 weeks, with soil and crop indicators sampled and measured at weeks 0, 2, 4 and 8.

[0083] 4) Controlled experimental design

[0084] Control group (CK): No amendments were applied. The same amount of deionized water as in step 3) was used for drip irrigation at a rate of 0.5 kg per square meter. The drip irrigation frequency was once a week for 3 hours each time. The experimental period was 8 weeks, and soil and crop indicators were sampled and measured in weeks 1, 2, 4 and 8.

[0085] Acid-only group: Take the same mass of hydrochloric acid from step 2) and the same mass of deionized water from step 3) to dilute the hydrochloric acid to obtain a diluted solution; use precision drip irrigation to evenly apply the obtained diluted solution to the saline-alkali soil at a rate of 0.5 kg per square meter; the drip irrigation frequency is once a week for 3 hours each time, the experimental period is 8 weeks, and soil and crop indicators are sampled and measured at weeks 0, 2, 4 and 8.

[0086] DESs alone group (DESs): The choline chloride-lactic acid water-soluble eutectic mixture obtained in step 1) was diluted with an equal mass of deionized water in step 3) to obtain a diluted solution; the diluted solution was evenly applied to the saline-alkali soil using a precise drip irrigation method, with an application rate of 0.5 kg per square meter; the drip irrigation frequency was once a week for 3 hours each time, and the experimental period was recommended to be maintained for 6 to 8 weeks, with soil and crop indicators sampled and measured in weeks 1, 2, 4 and 8.

[0087] Synergy: The scheme in this embodiment 2.

[0088] 5) Soil physicochemical index testing

[0089] This embodiment primarily targets strongly alkaline soil with pH ≈ 9.5 and EC ≈ 4.0 dS / m. Following the method in Example 1, soil pH, EC, ESP, CEC, and enzyme activity were measured at weeks 0, 2, 4, and 8. Exemplary data are shown in Table 4. This example uses an 8-week cycle, with 5 samples per group, and drip irrigation once a week for 3 hours each time.

[0090] Table 4. Effects of different treatments on soil pH, EC, ESP, and CEC.

[0091]

[0092]

[0093] illustrate:

[0094] I. Control group (CK), acid-only group, DESs-only group, and synergy group.

[0095] II. SE represents standard error.

[0096] III. As can be seen from the table above, the synergistic group showed the greatest decrease in pH and EC within 2 to 8 weeks, and the reduction in ESP and the increase in CEC were also significantly better than those using acid alone or DESs alone.

[0097] 6) Crop growth status and yield

[0098] Wheat (or other crops) were planted in the experiment. Under the same irrigation and maintenance conditions, the plant height, SPAD value, yield and grain protein content of each treatment group were compared, as shown in Table 5.

[0099] Table 5. Effects of different treatments on wheat growth and yield (Example 2 and control group)

[0100]

[0101] Comparative Example 2: Synergistic improvement of saline-alkali soil by choline chloride, lactic acid, and hydrochloric acid

[0102] 1) Preparation of water-soluble choline chloride-lactic acid + hydrochloric acid preparations

[0103] Choline chloride (first functional component), lactic acid (second functional component), and hydrochloric acid were mixed in the proportions of Example 2; the mixture was sonicated at 50°C for about 1.5 hours, then cooled to room temperature and stirred for 0.2 hours. The result was that the solution was turbid.

[0104] The preparation was diluted to 1% (mass percentage) with the same mass of deionized water as in step 3 of Example 2 to obtain a diluted solution. The diluted solution was then used to drip irrigate the soil of the same plot in Example 2. Wheat was selected as the test crop. Plant height, tiller number, chlorophyll content (SPAD value), final biomass, grain protein content and yield were measured in the 8th week. Five samples were measured, as shown in Table 6.

[0105] Table 6. Effects of different treatments on wheat growth and yield (Example 2 and comparative examples)

[0106]

[0107] Example 3: Synergistic improvement of saline-alkali soil with betaine-citric acid eutectic mixture and sulfuric acid

[0108] This embodiment is applicable to highly alkaline saline-alkali soil with pH≈9.0 and EC≈6.8dS / m. The comprehensive effects of rapid alkali reduction and increased yield brought about by the synergistic use of "betaine-citric acid" type DESs and sulfuric acid are verified through comparative experiments.

[0109] 1) Preparation of betaine-citric acid eutectic mixture (DESs)

[0110] Betaine (the first functional component) and citric acid (the second functional component) were mixed at a molar ratio of 1:4; the mixture was stirred at 70°C for about 2.5 hours until a homogeneous, transparent eutectic mixture was formed.

[0111] 2) Preparation of a formulation for the synergistic improvement of saline-alkali soil by water-soluble eutectic mixtures and acids.

[0112] Sulfuric acid (35wt%) was slowly added dropwise at 2% of the mass of the above mixture; the mixture was stirred at room temperature for 0.4 hours to obtain a stable water-soluble eutectic mixture-acid synergistic improvement preparation for saline-alkali soil, namely, a "betaine-citric acid + sulfuric acid" compound preparation.

[0113] 3. Application of amendment

[0114] 3) Application of the formulation and drip irrigation parameters

[0115] The water-soluble eutectic mixture-acid synergistic improvement agent for saline-alkali soil prepared in step 2) is diluted with deionized water to 3% (mass percentage), and 2 kg is applied per square meter of saline-alkali soil; drip irrigation frequency: 3 times a week, 1 hour each time, for 8 consecutive weeks; soil pH, EC, ESP and other indicators are tested simultaneously.

[0116] 4) Controlled experimental design

[0117] Control group: No amendments were applied. The same amount of deionized water as in step 3) was used for drip irrigation at a rate of 2 kg per square meter. The drip irrigation frequency was 3 times a week for 1 hour each time. The experimental period was 8 weeks, and soil and crop indicators were sampled and measured in weeks 2, 4, 6 and 8.

[0118] Acid-only group: Take the same mass of hydrochloric acid from step 2) and the same mass of deionized water from step 3) to dilute the sulfuric acid to obtain a diluted solution; use a precision drip irrigation method to evenly apply the obtained diluted solution to the saline-alkali soil at an application rate of 2 kg per square meter; the drip irrigation frequency is 3 times a week, 1 hour each time, the experimental period is 8 weeks, and soil and crop indicators are sampled and measured at weeks 0, 2, 4 and 8.

[0119] DESs group (DESs): The betaine-citric acid water-soluble eutectic mixture obtained in step 1) was diluted with the same mass of deionized water as in step 3) to obtain a diluted solution; the diluted solution was evenly applied to the saline-alkali soil using a precision drip irrigation method, with an application rate of 2 kg per square meter; the drip irrigation frequency was 3 times a week, 1 hour each time, for an 8-week experimental period, and soil and crop indicators were sampled and measured at weeks 0, 2, 4, and 8.

[0120] Synergy: The scheme in this embodiment 3.

[0121] 5) Soil physicochemical index testing

[0122] To more intuitively present the dynamic changes of pH and EC in each treatment group over treatment time (weeks), soil samples were collected at weeks 0, 2, 4, 6, and 8. Five samples were selected from each test group, and the data were measured and statistically analyzed as shown in Table 7. Furthermore, for ease of visualization, the results were plotted as follows: Figure 1 :

[0123] Table 7: pH and EC changes over time (Example 3 and control group)

[0124]

[0125]

[0126] Note: Different letter groups (a, b, c, etc.) at the same time point indicate significant differences (p<0.05, Tukey test).

[0127] 6) Crop growth status and yield

[0128] At crop maturity (8 weeks for wheat), the final yield and protein content of each treatment group were determined. The data are shown in Table 8.

[0129] Table 8: Final Yield and Protein Content Data

[0130]

[0131] This effect can also be seen from Figure 1 The bar chart clearly shows this. From Figure 1 It is evident that the synergistic group showed significantly higher yield and protein content than the control and single-treatment groups (p<0.05), further confirming the synergistic effect mechanism of "preparing a eutectic solvent first, then adding an acidic modifier and combining it with precise drip irrigation".

[0132] In summary, under the conditions of Example 3 (high pH≈9.0 soil), this invention, through the synergistic use of a betaine-citric acid type eutectic solvent with sulfuric acid and supplemented by precise drip irrigation, not only significantly reduced soil pH and EC within 6–8 weeks, but also substantially increased crop yield and protein content. Compared with the control, acid alone, or DESs alone, the synergistic group showed significant advantages.

Claims

1. A method for improving saline-alkali soil by water-soluble eutectic mixture-acid synergistic, characterized in that, The method comprises the following steps: 1) Preparation of a eutectic mixture: mixing the first functional component (A) and the second functional component (B) in a molar ratio of 1:1 to 1:10, stirring or ultrasonic treatment at a temperature in the range of 25°C to 80°C until a uniform, transparent and stable water-soluble eutectic mixture is formed; 2) Selection of an acidic modifier: selecting an inorganic acid or an organic acid as the acidic modifier according to the type of saline-alkali soil, the pH value, the salt composition and the crop tolerance; 3) Preparation of a preparation of a water-soluble eutectic mixture-acid synergistic modified saline-alkali soil: adding the acidic modifier selected in step (2) to the eutectic mixture prepared in step (1) in a proportion of 0.1% to 10% of the mass of the eutectic mixture, and stirring uniformly to obtain a preparation of a water-soluble eutectic mixture-acid synergistic modified saline-alkali soil; 4) Dilution: diluting the preparation with irrigation water to a concentration of 0.5wt% to 10wt%; 5) Precision drip irrigation application: applying the preparation diluted in step (4) to the saline-alkali soil by drip irrigation, the application amount being 0.1kg to 5kg per square meter of saline-alkali soil, the drip irrigation frequency being 1 to 3 times per week, and the drip irrigation time being 1 to 4 hours each time; The first functional component (A) is selected from one or more of the following: choline chloride, betaine, proline, lysine, arginine or glycine betaine; and the second functional component (B) is selected from one or more of the following: glycerol, ethylene glycol, propylene glycol, lactic acid, malic acid, citric acid, tartaric acid, succinic acid, glucose, fructose, sucrose, xylose, sorbitol, urea or acetamide.

2. The method of claim 1, wherein, The molar ratio of the first functional component (A) to the second functional component (B) is 1:2 to 1:8, and stirring or ultrasonic treatment is performed at a temperature of 40°C to 70°C for 1 to 3 hours until a uniform, transparent and stable water-soluble eutectic mixture is formed.

3. The method according to claim 1 or 2, characterized in that, The acidic modifier is selected from one or more of the following: hydrochloric acid, sulfuric acid, nitric acid, acetic acid, citric acid, lactic acid, malic acid, tartaric acid, succinic acid, formic acid, acetic acid, propionic acid or butyric acid.

4. The method according to claim 1 or 2, characterized in that, The first functional component (A) is selected from choline chloride or betaine, and the second functional component (B) is selected from glycerol, ethylene glycol, propylene glycol, lactic acid, malic acid, citric acid, tartaric acid or succinic acid; and the following selection is made according to different types of saline-alkali soil: For high-alkaline soil with a pH≥9.0, choline chloride or betaine is selected as the first functional component (A), and lactic acid, malic acid, citric acid, tartaric acid, succinic acid or a combination thereof is selected as the second functional component (B); For medium-high salt soil with an EC≥5 dS / m, choline chloride or betaine is selected as the first functional component (A), and glycerol, ethylene glycol, propylene glycol or a combination thereof is selected as the second functional component (B).

5. The method of claim 1, wherein, The molar ratio of the first functional component (A) to the second functional component (B) is 1:3-4.

6. The method of claim 1 or 2, wherein, The single application amount of the preparation at the drip irrigation link is 0.5kg to 3kg per square meter; and drip irrigation is performed in multiple times within 2 to 4 consecutive weeks during the main growth stage of the crop to achieve a rapid pH reduction and a stable modification effect.

7. The method according to claim 1 or 2, characterized in that, During the drip irrigation process, soil pH, electrical conductivity (EC) and crop growth indicators are monitored simultaneously to dynamically adjust the drip irrigation frequency or the concentration of the improvement agent, ensuring that the improvement effect is rapid and stable without causing excessive soil acidification.

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