A saline-alkali soil conditioner, its preparation method and application in improving saline-alkali soil

Abstract

The present invention discloses a saline-alkali soil conditioner, a preparation method thereof, and an application in improving saline-alkali soil, belonging to the technical field of saline-alkali soil improvement; the saline-alkali soil conditioner comprises the following components in parts by weight, 60-80 parts of inorganic acid-modified desulfurized gypsum, 2-5 parts of sodium lignosulfonate, 15-35 parts of acrylic acid, 35-45 parts of chitosan, 20-30 parts of acidic conditioner and 10-20 parts of dispersant; the preparation method of the saline-alkali soil conditioner is: adding the inorganic acid-modified desulfurized gypsum into deionized water, fully mixing, then adding the sodium lignosulfonate, acidic conditioner, dispersant, chitosan and acrylic acid, and after the reaction is sufficient, obtaining the saline-alkali soil conditioner through drying and granulation; when the conditioner is applied to improve saline-alkali soil, it can significantly improve the salt and alkalinity of saline-alkali soil, and at the same time has extremely strong water absorption, water retention and anti-caking properties.

Description

Technical Field

[0001] The present invention relates to the technical field of saline-alkali land improvement, and specifically to a saline-alkali land conditioner and a preparation method thereof. Background Art

[0002] Saline-alkali land is a type of land where salts accumulate, referring to land where the salts contained in the soil affect the normal growth of crops. According to incomplete statistics by UNESCO and the Food and Agriculture Organization, the area of saline-alkali land worldwide is 954.38 million hectares, of which 99.13 million hectares are in China. The formation of alkali soil and alkalized soil in China is mostly related to the accumulation of carbonates in the soil, so the degree of alkalization is generally high. Soil salinization can lead to high soil dispersion, swelling when wet, hardening when dry, and very poor permeability, seriously hindering the growth and development of crops. It can cause two harms to plants. One is the toxic effect. When plants absorb more sodium ions or chloride ions, it will change the structure and function of cell membranes, and ultimately cause plant death. The other is to increase the osmotic pressure of the soil, causing resistance to the absorption of plant roots, making it difficult for plants to absorb water, resulting in cell dehydration, plant wilting, and finally plant death. Therefore, taking effective measures to improve saline-alkali land is an urgent problem to be solved currently.

[0003] In recent years, desulfurized gypsum has developed rapidly as a saline-alkali land conditioner. Its improvement mechanism is the same as that of natural gypsum. It mainly uses calcium ions in desulfurized gypsum to exchange replaceable sodium ions on soil colloids, so that sodium ions transfer from soil colloids into the soil solution and enter the groundwater with irrigation water or are drained away by drainage channels. Currently, desulfurized gypsum is often mixed with acidic conditioners (such as humic acid) and used for saline-alkali land improvement. However, during the improvement process, desulfurized gypsum is extremely prone to agglomeration, resulting in difficulty in effectively exchanging ions with the soil, reducing the improvement effect. At the same time, desulfurized soil is difficult to effectively improve problems such as soil hardening and drainage, and has certain limitations in practical applications. In addition, the acidic conditioner has a short effective action time. Especially when it rains, it is extremely easy to cause its loss, further affecting the improvement effect. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a saline-alkali land conditioner, a preparation method thereof, and an application in improving saline-alkali land, so as to at least achieve the purpose of effectively improving soil hardening of saline-alkali land and reducing the salinity of saline-alkali land.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A saline-alkali land conditioner, comprising the following components in parts by weight,

[0007] 60 - 80 parts of inorganic acid - modified desulfurized gypsum, 2 - 5 parts of sodium lignosulfonate, 15 - 35 parts of acrylic acid, 35 - 45 parts of chitosan, 20 - 30 parts of acidic modifier and 10 - 20 parts of dispersant.

[0008] In the above - mentioned scheme, the inorganic acid - modified desulfurized gypsum contains ferric sulfate, and ferric ions have oxidizing properties. It can undergo an oxidation - reduction reaction with chitosan to generate chitosan macromolecular free radicals. Subsequently, the macromolecular free radicals undergo a graft copolymerization reaction with acrylic acid to obtain a macromolecular substance. After acting together with high - molecular sodium lignosulfonate, a resin - like substance with a high - molecular skeleton is obtained. The high - molecular skeleton of this resin - like substance can play a slow - release role for the acidic modifier, increasing the improvement time limit. At the same time, it can also disperse solid substances such as gypsum particles within the skeleton, avoiding the agglomeration of gypsum, and then significantly improving the exchange effect with sodium ions in the soil, ensuring that the gypsum particles play a uniform and continuous improvement role in coordination with other components, overcoming the defect in the prior art that directly spreading gypsum on the soil results in the agglomeration of gypsum particles and difficulty in improving soil compaction, leading to poor improvement effects. By adding a dispersant to the reaction system, solid ions can be fully mixed with the liquid, thereby improving the dispersion uniformity of solid particles such as gypsum in the saline - alkali land modifier, so that the improvement effects at various parts of the saline - alkali land modifier are balanced. In addition, in addition to being able to generate resin - like substances, chitosan also acts as a binder, which can effectively improve the adhesion stability of desulfurized gypsum in the saline - alkali land modifier, while improving the integrity of the saline - alkali land modifier and reducing the probability of fragmentation and powder shedding during production and use.

[0009] Through the synergistic effect of the above - mentioned components, the prepared saline - alkali land modifier can have strong water - absorption, water - retention, anti - compaction, and saline - alkali land improvement effects.

[0010] Preferably, the saline - alkali land modifier comprises the following components in parts by weight

[0011] 65 - 75 parts of inorganic acid - modified desulfurized gypsum, 3 - 4 parts of sodium lignosulfonate, 16 - 25 parts of acrylic acid, 38 - 43 parts of chitosan, 25 - 28 parts of acidic modifier and 15 - 18 parts of dispersant. By further limiting the dosage of the saline - alkali land modifier, the improvement effect can be further improved.

[0012] Preferably, the preparation method of the inorganic acid - modified desulfurized gypsum is as follows:

[0013] Add desulfurized gypsum into deionized water, then add sulfuric acid. After fully reacting, add iron powder. After the reaction is complete, filter and remove the iron powder in the filter residue. Then dry and calcine the filter residue to obtain the inorganic acid - modified desulfurized gypsum.

[0014] In the above solution, by adding sulfuric acid, the unreacted calcium carbonate and incompletely reacted calcium sulfite in the gypsum desulfurization process can be converted into the active ingredient calcium sulfate, reducing the harm of carbonates to saline-alkali land and enhancing the ability of desulfurized gypsum to treat saline-alkali land. Secondly, sulfuric acid can form solid acids with components such as Fe and Al oxides in desulfurized gypsum, thereby promoting the exchange of Ca ions and Na ions in desulfurized gypsum and reducing the pH of saline-alkali land. Moreover, the formed solid acids and other components can penetrate deep into the saline-alkali land, improving the treatment of deep saline-alkali land. By adding iron powder, the incompletely reacted sulfuric acid can be completely reacted. Through drying and roasting, the pore size and volume of inorganic acid desulfurized gypsum can be increased, so that when forming a saline-alkali land conditioner, the space occupancy rate of inorganic acid desulfurized gypsum in resinous substances can be increased, thereby improving the efficiency of inorganic acid desulfurized gypsum in improving saline-alkali land. In addition, during the drying and roasting process, ferrous ions can be completely converted into ferric ions, providing a certain supplement for its subsequent reaction with chitosan to ensure the smooth formation of resinous substances.

[0015] Preferably, the roasting temperature is 300 - 400 °C and the roasting time is 1 - 1.5 h.

[0016] In the above solution, by limiting the roasting temperature and time, the pore size of inorganic acid desulfurized gypsum can be maximally increased to maximally improve its space occupancy rate in the saline-alkali land conditioner.

[0017] Preferably, the dispersant includes modified silica white and ethylene glycol.

[0018] In the above solution, the combined action of silica white and hexanediol can significantly improve the dispersion effect of each component, thereby ensuring that solid ions can be fully mixed with the liquid to improve the dispersion degree of the saline-alkali land conditioner. In addition, compared with silica white, modified silica white has a low surface energy and is not easy to agglomerate. The modification method and modifier are both existing technologies, and the modifier can be a silane coupling agent, an alcohol ester modifier, an organic acid or an organic salt, etc. Further, due to the unstable viscosity of chitosan in the reaction system, which will decrease, resulting in problems such as powder shedding of the prepared saline-alkali land conditioner and a decline in the improvement effect. By adding hexanediol in the dispersant, the viscosity of chitosan can be stabilized, ensuring that solid particles can be stably combined in the saline-alkali land conditioner and reducing the phenomena of powder shedding and fragmentation.

[0019] Preferably, the acidic conditioner is one or more of humic acid and wood vinegar.

[0020] In addition, to achieve the above object, the present invention also provides a preparation method of a saline-alkali land conditioner, including the following steps:

[0021] The inorganic acid modified desulfurized gypsum is added into deionized water, and after being fully mixed, the sodium lignin sulfonate, the acidic modifier, the dispersant, chitosan and acrylic acid are added, and after the reaction is sufficient, the saline-alkali land modifier is obtained after drying and granulation.

[0022] In the above scheme, the inorganic acid modified desulfurized gypsum is first dispersed in ionized water to form a suspension, and then sodium lignin sulfonate and a dispersant are added to evenly disperse the solid particles in the solution while ensuring the stability of the adhesion in the chitosan; chitosan macromolecular free radicals are formed after the addition of chitosan, and then acrylic acid is added to react with the macromolecular free radicals, and then the reaction mixture is dried and granulated to obtain the saline-alkali land improver.

[0023] In addition, in order to achieve the above-mentioned purpose, the present invention also proposes the use of a saline-alkali land improver in improving saline-alkali land, and the saline-alkali land improving method is as follows:

[0024] S1. Evenly spread the saline-alkali land improver on the surface of the saline-alkali land to be improved; then rotary till the saline-alkali land by 20-30 cm; after the rotary tillage is completed, deep tillage is further performed by 40-60 cm;

[0025] S2 evenly spreads the saline-alkali land improver on the surface of the deep-turned saline-alkali land; then rotary tills the saline-alkali land to 20-30 cm;

[0026] S3. After 1-2 months, irrigate the land to wash away salt and alkali.

[0027] In the above scheme, the saline-alkali land improver is sprinkled on the soil surface and rotary tilled to eliminate soil surface compaction, increase soil permeability and permeability, and then deep plowing is performed to increase the soil improvement depth; after deep plowing, the saline-alkali land improver is sprinkled on the soil surface to further improve the saline-alkali land improvement effect. In this process, the acidic improver is slowly released to react with soil colloids for neutralization, and at the same time, the sodium ions in the soil exchange with the calcium ions and aluminum ions in the saline-alkali land improver; after 1-2 months, watering the land can wash away the exchanged sodium ions and other salts to reduce salinity. By applying the saline-alkali land improver to improve saline-alkali land, a very significant effect can be achieved.

[0028] The beneficial effects of the present invention are:

[0029] The present invention configures an acid-modified desulfurized gypsum, sodium lignosulfonate, acrylic acid, chitosan, acid modifier, and dispersant into a saline-alkali soil conditioner according to certain dosages, which can significantly improve the salt and alkalinity of saline-alkali soil, and at the same time has extremely strong water absorption, water retention, and anti-caking properties. Specifically, by adding acid-modified desulfurized gypsum, the trivalent iron ions therein can undergo an oxidation-reduction reaction with chitosan to generate chitosan macromolecular free radicals. Subsequently, the macromolecular free radicals undergo a graft copolymerization reaction with acrylic acid to obtain a macromolecular substance. After acting together with high-molecular sodium lignosulfonate, a resin-like substance with a high-molecular skeleton is obtained. This resin-like substance can play a slow-release role in the acid modifier, increasing the improvement time limit. By adding a dispersant, solid particles can be fully mixed with the liquid, thereby improving the dispersion uniformity of gypsum particles in the saline-alkali soil conditioner, so that the improvement effects at various parts of the saline-alkali soil conditioner are balanced. At the same time, by uniformly dispersing gypsum particles in the skeleton of the resin-like substance, the aggregation of gypsum can be avoided, thereby significantly improving the exchange effect with sodium ions in the soil, and further improving the improvement effect. In addition, in addition to generating resin-like substances, chitosan also acts as a binder, which can effectively improve the adhesion stability of desulfurized gypsum in the saline-alkali soil conditioner, and at the same time improve the integrity of the saline-alkali soil conditioner, reducing the probability of breakage and powder shedding during production and use. Detailed implementation mode

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0031] Example 1

[0032] The application of a saline-alkali soil conditioner in improving saline-alkali soil is as follows:

[0033] S1. Uniformly sprinkle the saline-alkali soil conditioner on the surface of a saline-alkali soil in Wenshan, Yunnan, with a dosage of 500 kg / mu; then rotary till the saline-alkali soil to a depth of 20 - 25 cm; after the rotary tillage is completed, deeply plow it to a depth of 45 - 50 cm;

[0034] S2. Uniformly sprinkle the saline-alkali soil conditioner on the surface of the deeply plowed saline-alkali soil, with a dosage of 350 kg / mu; then rotary till the saline-alkali soil to a depth of 20 - 25 cm;

[0035] S3. After 1 month, irrigate the land to wash salt and remove alkali.

[0036] Among them, the preparation method of the above-mentioned saline-alkali soil conditioner is as follows:

[0037] S01: Mix desulfurized gypsum and deionized water in a mass ratio of 1:2-2.5, then add concentrated sulfuric acid to make the sulfuric acid concentration in the system 0.3-0.5 mol / L, then fully react for 4-5 hours under stirring, then slowly add iron powder to the system under stirring until no bubbles are generated, then filter and magnetically absorb a small amount of iron powder in the filter residue, then dry the filter residue and roast it at 350°C for 1 hour to obtain inorganic acid modified desulfurized gypsum;

[0038] S02 Take 80 parts of inorganic acid modified desulfurized gypsum and add them to deionized water with an amount twice its weight. After thorough mixing, add 3 parts of sodium lignin sulfonate, 25 parts of acidic modifier (including humic acid and wood acetic acid, the mass ratio of the two is 2:1), 20 parts of dispersant (the mass ratio of modified silica and ethylene glycol is 2:5, and the modified silica in this embodiment is prepared by the method in application number CN202011621416.7), 38 parts of chitosan and 18 parts of acrylic acid, then fill with nitrogen and react at 50-60°C for 1.5-2h, and then dry and granulate (drying and granulation are conventional methods and will not be described in detail) to obtain the saline-alkali land modifier.

[0039] Example 2

[0040] A saline-alkali land improver is used in improving saline-alkali land as follows:

[0041] S1. Evenly sprinkle the saline-alkali land improver on the surface of a saline-alkali land in Wenshan, Yunnan (the same place as in Example 1), with an addition amount of 500 kg / mu; then rotary till the saline-alkali land by 20-25 cm; after the rotary tillage is completed, deep plowing is performed by 45-50 cm;

[0042] S2 evenly spread the saline-alkali land improver on the surface of the deep-turned saline-alkali land, with an addition amount of 350kg / mu; then rotary till the saline-alkali land to 20-25cm;

[0043] S3. After one month, irrigate the land to wash away salt and alkali.

[0044] Wherein, the preparation method of the above-mentioned saline-alkali land improver is:

[0045] S01: Mix desulfurized gypsum and deionized water in a mass ratio of 1:2-2.5, then add concentrated sulfuric acid to make the sulfuric acid concentration in the system 0.3-0.5 mol / L, then fully react for 4-5 hours under stirring, then slowly add iron powder to the system under stirring until no bubbles are generated, then filter and magnetically absorb a small amount of iron powder in the filter residue, then dry the filter residue and roast it at 250°C for 1.5 hours to obtain inorganic acid modified desulfurized gypsum;

[0046] S02 Take 68 parts of inorganic acid modified desulfurized gypsum and add them to deionized water with an amount twice its weight. After thorough mixing, add 3 parts of sodium lignin sulfonate, 28 parts of acidic modifier (the mass ratio of modified silica and ethylene glycol is 2:5, and the modified silica in this embodiment is prepared by the method in application number CN202011621416.7), 16 parts of dispersant (the mass ratio of modified silica and ethylene glycol is 2:5, and the modified silica in this embodiment is prepared by the method in application number CN202011621416.7), 40 parts of chitosan and 18 parts of acrylic acid, then fill with nitrogen and react at 50-60°C for 1.5-2h, and then dry and granulate (drying and granulation are conventional methods, which will not be described here) to obtain the saline-alkali land modifier.

[0047] Example 3

[0048] A saline-alkali land improver is used in improving saline-alkali land as follows:

[0049] S1. Evenly sprinkle the saline-alkali land improver on the surface of a saline-alkali land in Wenshan, Yunnan (the same place as in Example 1), with an addition amount of 500 kg / mu; then rotary till the saline-alkali land by 20-25 cm; after the rotary tillage is completed, deep plowing is performed by 45-50 cm;

[0050] S2 evenly spread the saline-alkali land improver on the surface of the deep-turned saline-alkali land, with an addition amount of 350kg / mu; then rotary till the saline-alkali land to 20-25cm;

[0051] S3. After one month, irrigate the land to wash away salt and alkali.

[0052] Wherein, the preparation method of the above-mentioned saline-alkali land improver is:

[0053] S01: Mix desulfurized gypsum and deionized water in a mass ratio of 1:2-2.5, then add concentrated sulfuric acid to make the sulfuric acid concentration in the system 0.3-0.5 mol / L, then fully react for 4-5 hours under stirring, then slowly add iron powder to the system under stirring until no bubbles are generated, then filter and magnetically absorb a small amount of iron powder in the filter residue, then dry the filter residue and roast it at 350°C for 1 hour to obtain inorganic acid modified desulfurized gypsum;

[0054] S02 Take 70 parts of inorganic acid-modified desulfurized gypsum and add it to deionized water twice its weight. After thorough mixing, add 4 parts of sodium lignin sulfonate, 28 parts of acidic modifier (the mass ratio of modified silica and ethylene glycol is 2:5, and the modified silica in this embodiment is prepared by the method in application number CN202011621416.7), 18 parts of dispersant (the mass ratio of modified silica and ethylene glycol is 2:5, and the modified silica in this embodiment is prepared by the method in application number CN202011621416.7), 36 parts of chitosan and 22 parts of acrylic acid, then fill with nitrogen and react at 50-60°C for 1.5-2h, and then dry and granulate (drying and granulation are conventional methods and will not be repeated here) to obtain the saline-alkali land modifier.

[0055] Comparative Example 1

[0056] Compared with Example 2, the amount of chitosan was changed from 40 parts to 20 parts, and the rest remained unchanged.

[0057] Comparative Example 2

[0058] Compared with Example 2, the mass ratio of modified silica to hexylene glycol in the dispersant was changed from 2:5 to 3:5, and the rest remained unchanged.

[0059] Comparative Example 3

[0060] The preparation method of the saline-alkali land improver is as follows: 68 parts of desulfurized gypsum are added into deionized water twice its weight, and then 28 parts of acidic improver are added, and after the reaction is sufficient, drying and roasting are performed to obtain the saline-alkali land improver.

[0061] The method for applying the saline-alkali land improving agent to improve saline-alkali land is the same as that in Example 2.

[0062] Test example

[0063] 1. The chipping and breakage of the saline-alkali land improvers in Examples 1-3 and Comparative Examples 1-2 were observed, and the water absorption and water retention properties of the saline-alkali land improvers in Test Examples 1-3 and Comparative Examples 1-2 were measured. The results are shown in Table 1.

[0064] Table 1

[0065]

[0066] Note: The above-mentioned mutual collision refers to the collision during material collection, routine transfer and packaging after production, not deliberate collision.

[0067] As can be seen from Table 1, the degree of chipping and breaking of the saline-alkali land conditioner prepared according to the formula, dosage and preparation method in the present invention is relatively slight, which reflects that the bonding degree of the saline-alkali land conditioner is moderate and the stability is strong. Furthermore, it reduces the probability of gypsum detaching from the surface of the conditioner when improving the saline-alkali land and avoids its agglomeration. In Comparative Example 1, due to the reduction in the dosage of chitosan, the bonding degree decreased, resulting in the prepared saline-alkali land conditioner being loose and difficult to granulate. In Comparative Example 2, due to the reduction in hexanediol, the bonding degree of chitosan in the system decreased, also resulting in the same result as in Comparative Example 2. Further, it can also be seen from Table 1 that the water absorption and water retention properties of the saline-alkali land conditioner prepared in the present invention are extremely strong. It can quickly make water penetrate the soil and delay the rapid diffusion of water, ensuring the water content in the soil and effectively improving the soil compaction degree. In Comparative Example 1, due to the reduction in the dosage of chitosan, it is difficult to effectively generate resinous substances with a high molecular skeleton in the reaction system, resulting in the saline-alkali land conditioner being loose and affecting the water absorption capacity. In Comparative Example 2, the saline-alkali land conditioner is also loose, affecting the water absorption capacity. Thus, it can be seen that through the combined action of the components in the present invention, a structural substance with high water absorption and high water retention can be formed.

[0068] 2. Take a saline-alkali land in Wenshan, Yunnan (the same place as in Example 1). By digging deep trenches, it is divided into 6 parts, and the saline-alkali land conditioners and improvement methods in Examples 1-3 and Comparative Examples 1-3 are used for simultaneous improvement. On the 0th, 2nd, 10th, and 30th days of improvement, the salt concentration EC value and pH value of the soil at a depth of 30-35 cm are detected, and the test results are shown in Table 1.

[0069] Table 2

[0070]

[0071] As can be seen from Table 2, for the conditioners in Examples 1-3, on the 2nd day of improvement, the salt concentration and pH value of the saline-alkali land have been significantly improved, and during the period from the 2nd day to the 30th day, the conditioner can continuously exert an excellent improvement effect. By the 30th day, the improvement effect of the saline-alkali land is better. While for Comparative Examples 1-3, the overall improvement speed within 30 days is slower, and the improvement effect of the saline-alkali land on the 30th day is not very ideal. Thus, it can be seen that the conditioners in Examples 1-3 of the present invention are more excellent in terms of improvement speed and improvement effect compared to Comparative Examples 1-3.

[0072] In addition, during the process of using the saline-alkali land conditioner to improve the soil, the conditioners in Comparative Examples 1-3 can effectively improve the soil compaction degree of the saline-alkali land, and the effect is far better than that of Comparative Examples 1-3. In particular, Comparative Example 3 has no obvious effect on resisting soil compaction.

[0073] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. As long as the changes and variations made by those skilled in the art do not depart from the spirit and scope of the present invention, they should all be within the protection scope of the appended claims of the present invention.

Claims

1. A saline-alkali soil conditioner, characterized in that, Its raw materials include the following components in parts by weight: 60 - 80 parts of inorganic acid - modified desulfurized gypsum, 2 - 5 parts of sodium lignosulfonate, 15 - 35 parts of acrylic acid, 35 - 45 parts of chitosan, 20 - 30 parts of acid modifier, and 10 - 20 parts of dispersant; The preparation method of the inorganic acid - modified desulfurized gypsum is as follows: Add desulfurized gypsum into deionized water, then add sulfuric acid. After fully reacting, add iron powder. After the reaction is complete, filter and remove the iron powder in the filter residue. Then dry and roast the filter residue to obtain the inorganic acid - modified desulfurized gypsum; The roasting temperature is 300 - 400 °C, and the roasting time is 1 - 1.5 h.

2. The soil conditioner for saline-alkali land according to claim 1, wherein Its raw materials include the following components in parts by weight: 65 - 75 parts of inorganic acid - modified desulfurized gypsum, 3 - 4 parts of sodium lignosulfonate, 16 - 25 parts of acrylic acid, 38 - 43 parts of chitosan, 25 - 28 parts of acid modifier, and 15 - 18 parts of dispersant.

3. The soil conditioner for saline-alkali land according to claim 1, wherein The dispersant includes modified silica white and ethylene glycol.

4. The soil conditioner for saline-alkali land according to claim 1, characterized in that The acid modifier is one or more of humic acid and wood vinegar.

5. The preparation method of a saline-alkali land conditioner according to any one of claims 1-4, characterized in that, It includes the following steps: Add the inorganic acid - modified desulfurized gypsum into deionized water. After fully mixing, add the sodium lignosulfonate, acid modifier, dispersant, chitosan, and acrylic acid. After the reaction is complete, obtain the saline - alkali land conditioner through drying and granulation.

6. Use of a saline-alkali soil conditioner according to any one of claims 1-4 in improving saline-alkali soil, characterized in that, The improvement method for the saline - alkali land is as follows: S1. Uniformly sprinkle the saline - alkali land conditioner on the surface of the saline - alkali land to be improved; then rotary till the saline - alkali land by 20 - 30 cm; after the rotary tillage is completed, deeply plow by 40 - 60 cm; S2. Uniformly sprinkle the saline - alkali land conditioner on the surface of the deeply plowed saline - alkali land; then rotary till the saline - alkali land by 20 - 30 cm; S3. After 1 - 2 months, irrigate the land to wash salt and remove alkali.

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