Saline-alkali land treatment method using chemical adsorption and microbial remediation

Abstract

The present application relates to the technical field of soil improvement, and particularly relates to a saline-alkali soil treatment method using chemical adsorption and microbial remediation. First, an adsorbent is prepared: a composite microbial population is prepared by mixing lactobacillus plantarum, bacillus megaterium and halomonas; a carrier is prepared by modifying bentonite with hydrogen and humic acid through amino grafting; vitamin B group and EDTA chelated trace elements are prepared into nutritional microcapsules, and the modified carrier and the microbial population are mixed to obtain the adsorbent. During treatment, the soil is deep ploughed, the adsorbent is applied at a gradient of 30-100 kg per mu for light, medium and heavy saline-alkali soil, and is mixed and irrigated by rotary ploughing, and the first leaching is performed after 7 days, and subsequent monitoring and control are performed until the standard is reached. Through the synergistic effect of rapid salt reduction by chemical adsorption and long-term consolidation by microbial remediation, the pH, soil structure and fertility are simultaneously optimized, the adaptability is wide, and water is saved and efficient, and the method is suitable for treatment of various saline-alkali soils.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improvement, and particularly relates to a saline-alkali soil treatment method using chemical adsorption and microbial remediation. BACKGROUND

[0002] Saline-alkali soil is one of the most important types of soil degradation in the world, which is widely distributed in coastal, inland irrigation and arid and semi-arid regions, and poses a serious threat to agricultural production and ecological safety. The total area of saline-alkali soil in China has exceeded 1.5 billion mu, of which about 500 million mu has the potential for improvement. Due to the long-term high salinity and high pH, the soil colloidal structure is destroyed, showing obvious hardening characteristics, resulting in a sharp decline in soil fertility, and crops are difficult to survive, which not only restricts the sustainable development of agriculture, but also causes the fragmentation of the ecological system, and reduces the stability and anti-interference ability of the regional ecological system.

[0003] Saline-alkali soil treatment has gone beyond the scope of simple soil improvement and is closely related to the improvement of ecological carbon sinks. A healthy soil ecosystem is an important carbon sink, and a degraded saline-alkali soil has extremely low organic matter content, weak microbial activity, and insufficient carbon sink capacity, and may even become a potential "carbon source" due to abnormal soil respiration. Studies have shown that after scientific treatment of saline-alkali soil, the improvement of soil aggregate structure can promote the accumulation of organic matter, and the restoration and optimization of microbial community can accelerate the transformation of carbon cycle to carbon sequestration. The annual carbon sequestration potential of improved saline-alkali soil per hectare can reach several tons to several dozen tons. Therefore, saline-alkali soil treatment is not only the key to solving the bottleneck of agricultural development, but also the improvement of the carbon sink capacity of the ecological system.

[0004] Although the current mainstream saline-alkali soil treatment technologies have their own focuses, they all have significant defects and are difficult to balance the treatment effect and carbon reduction and sequestration needs. Chemical improvement method (such as applying gypsum and phosphogypsum) can reduce the content of soil exchangeable sodium in the short term, but it can easily aggravate soil hardening, destroy the soil microbial habitat, accelerate the decomposition of organic matter, and even weaken the soil carbon sequestration capacity, and may even cause secondary pollution; biological remediation method (such as single inoculation of salt-tolerant bacteria) relies on bacterial metabolism to reduce salt, but in a high-salt and high-alkali environment, it is difficult for the bacterial community to colonize and has low activity, and the remediation period is as long as 1-2 years, and it cannot quickly build a stable soil carbon sink system; physical leaching method needs to consume a large amount of water resources, which not only wastes resources, but also may cause salt ions to migrate to deep soil, interfering with the stability of the deep soil carbon pool; traditional chemical adsorbents (such as single bentonite) have limited adsorption capacity, and after adsorption equilibrium, salt ions are easily desorbed and rebound, and they do not have the function of promoting organic matter accumulation, and cannot realize the coordinated promotion of treatment and carbon sequestration. SUMMARY

[0005] The purpose of the present application is to solve the defects in the prior art, and a saline-alkali soil treatment method using chemical adsorption and microbial remediation is provided.

[0006] To achieve the above objectives, the present invention provides a method for preparing an adsorbent for treating saline-alkali land, comprising the following steps:

[0007] (1) Select acid-producing bacteria, phosphate-solubilizing bacteria, and salt-tolerant functional bacteria, respectively, and inoculate them into the culture medium for fermentation and propagation to obtain the fermentation broth of each strain. Resuspend the fermentation broth of each strain in sterile physiological saline to obtain a concentration of 10. 9 -10 10 A CFU / mL bacterial suspension was prepared by mixing the bacterial suspension with acid-producing bacteria suspension, phosphate-solubilizing bacteria suspension, and salt-tolerant functional bacteria suspension in a weight ratio of 1-3:1-3:0.8-1.2 to obtain a compound bacterial agent.

[0008] (2) Mix hydrogen-based bentonite, humic acid and deionized water, stir at 30-40℃ for 20-40 min, then heat to 40-50℃ and continue stirring for 1-3 h, filter, wash the obtained product, dry it and pulverize it through a 100-mesh sieve to obtain the adsorbent carrier; in the process, the core structure of hydrogen-based bentonite is layered aluminosilicate (the layers contain a large number of Al-OH and Si-OH groups), and humic acid is based on an aromatic ring and connected with functional groups such as carboxyl and phenolic hydroxyl groups. The two are stably combined through two strong interactions. On the one hand, the electronegative H in Al-OH / Si-OH on the surface of hydrogen-based bentonite forms strong hydrogen bonds with the C=O oxygen (electronegative) of -COOH and the oxygen of -Ar-OH in humic acid. On the other hand, at 40-50℃, the -COOH of humic acid partially dissociates into -COO. - H between the hydrogen-based bentonite layer + A weak electrostatic interaction is formed, and the two work synergistically to enhance the stability of the bond;

[0009] (3) The adsorbent carrier, N,N-dicyclohexylcarbodiimide, 4-dimethylpyridine and anhydrous N,N-dimethylformamide were mixed, and then N-acetylethylenediamine was added. The mixture was stirred at room temperature for 5-7 hours, centrifuged, and the product was washed, dried and pulverized through a 100-mesh sieve to obtain the adsorbent carrier containing acetyl groups.

[0010] (4) The adsorbent carrier containing acetyl is mixed with hydrochloric acid with a concentration of 10 mol / L, and is placed in a polytetrafluoroethylene reactor at 80-100°C for 8-12 hours. After cooling to room temperature, centrifugal separation is performed, the product is washed with deionized water until the filtrate is neutral, and is dried and crushed to pass through a 100-mesh screen to obtain an adsorbent carrier containing amino groups; during the hydrolysis process, the acetyl amide bond can be selectively hydrolyzed, while the amide bond between the adsorbent and N-acetyl ethylenediamine remains stable, and the core mechanism is derived from the synergistic adaptation of the electronic effect, steric hindrance difference and hydrolysis conditions of the two amide bonds. From the electronic effect, the terminal acetyl group in the acetyl amide bond is a strong electron-withdrawing group, which significantly reduces the electron cloud density of the adjacent N atom through conjugation effect, greatly enhances the polarity of the C-N bond of the amide bond, and reduces the bond energy, becoming a weak bond easily attacked by H + ; while in the amide bond between N-acetyl ethylenediamine and the adsorbent, the N atom is directly connected to the side chain of humic acid, and the aromatic ring is the core skeleton of humic acid. The large conjugated system can effectively weaken the electron-withdrawing effect of the self-CO-group, so that the electron cloud density of the N atom in the amide bond is maintained at a high level, the C-N bond polarity is weaker and the bond energy is improved, and the resistance to H + attack is significantly enhanced; from the perspective of steric hindrance, the acetyl amide bond is located at the end of the grafted molecular chain, far away from the main body of the adsorbent carrier, and the acetyl group has a small volume and no obvious steric barrier around it, so H + can freely diffuse to the vicinity of the C-N bond of the amide bond and initiate an effective attack, while the amide bond of the adsorbent is directly connected to the humic acid-hydrogen bentonite complex, and the aromatic ring skeleton of humic acid has a large volume and dense structure, forming a steric barrier around the amide bond. The layered structure of hydrogen bentonite further limits the diffusion path of H + , only a small amount of H + can enter the interlayer region and preferentially react with the acetyl amide bond exposed outside, and it is difficult to contact the adsorbent-connected amide bond wrapped by the carrier structure, so that only the acetyl amide bond is hydrolyzed to release primary amino groups, while the adsorbent-connected amide bond is stably retained to maintain the integrity of the carrier structure and the continuity of the function;

[0011] (5) Vitamin B group, EDTA chelated trace elements and deionized water are mixed to prepare a nutrient factor solution, then mixed with a chitosan aqueous solution with a mass concentration of 1-3% after ultrasonic emulsification, dropwise added with a sodium alginate aqueous solution with a mass concentration of 1-3%, and dropwise added with a CaCl2 solution with a concentration of 1 mol / L, stirred and reacted for 20-40 min, filtered, washed, dried, and then a nutrient factor microcapsule is obtained. The nutrient factor microcapsule, the adsorbent carrier containing amino groups and the complex microbial population inoculant are mixed, stirred at 20-30°C for 1-2 h, then filtered, dried, and then an adsorbent for treating saline-alkali soil is obtained.

[0012] Preferably, the acid-producing bacteria in (1) refer to Lactobacillus plantarum, the phosphorus-dissolving bacteria refer to Bacillus megaterium, and the salt-tolerant functional bacteria refer to Halomonas.

[0013] Preferably, the bentonite, humic acid and deionized water in (2) are in a weight ratio of 1:0.2-0.4:15-25.

[0014] Preferably, the adsorbent carrier, N,N-dicyclohexyl carbodiimide, 4-dimethylpyridine, anhydrous N,N-dimethylformamide and N-acetyl ethylenediamine in (3) are in a weight ratio of 1:0.2-0.3:0.03-0.05:15-25:0.08-0.16.

[0015] Preferably, the adsorbent carrier with acetyl and hydrochloric acid with a concentration of 10 mol / L in (4) are in a weight ratio of 1:3-7.

[0016] Preferably, the vitamin B group, EDTA chelated trace elements and deionized water in (5) are in a weight ratio of 1:1:8-12.

[0017] Preferably, the nutrient factor solution, chitosan aqueous solution with a mass concentration of 1-3%, sodium alginate aqueous solution with a mass concentration of 1-3% and CaCl2 solution with a concentration of 1 mol / L in (5) are in a weight ratio of 1:1.5-2.5:0.5-1.5:0.05-0.1.

[0018] Preferably, the nutrient factor microcapsule, the adsorbent carrier containing amino and the complex bacterial group bacteria agent in (5) are in a weight ratio of 1:8-12:80-100.

[0019] Preferably, the vitamin B group in (5) refers to a mixture of vitamin B1, vitamin B2, vitamin B6 and vitamin B12 in a weight ratio of 1:1:1:1.

[0020] Preferably, the EDTA chelated trace elements in (5) refer to a mixture of EDTA chelated Fe 2+ , EDTA chelated Zn 2+ , EDTA chelated Mn 2+ in a molar ratio of 2:2:1.

[0021] Further, the application also provides a saline-alkali soil treatment method using chemical adsorption and microbial remediation, and the application further provides a saline-alkali soil treatment method using chemical adsorption and microbial remediation.

[0022] S1. Soil pretreatment: deep ploughing is performed on the target saline-alkali soil, the deep ploughing depth is 20-30 cm, and the initial conductivity, pH value and exchangeable sodium percentage of the soil are determined.

[0023] S2. Based on the initial soil salinity, apply the adsorbent for treating saline-alkali land evenly at the following dosages: 30-50 kg / mu for mildly saline-alkali land, 50-80 kg / mu for moderately saline-alkali land, and 80-100 kg / mu for severely saline-alkali land. Thoroughly mix the adsorbent with the 0-20cm soil layer by rotary tillage, then irrigate with 50-60 ml of water. 3 / mu;

[0024] S3. The first rinsing should be carried out on the 7th day after application, with a rinsing volume of 80-100m³. 3 / mu, then monitor soil electrical conductivity and pH every 30 days. If soil electrical conductivity >5dS / m or pH >9.0, perform an additional leaching, with an irrigation volume of 60-80m³. 3 / mu; when the soil electrical conductivity is ≤3dS / m for two consecutive monitoring sessions and the pH is ≤8 for two consecutive monitoring sessions, it is determined that the saline-alkali land treatment target has been achieved and the treatment of the saline-alkali land has been completed.

[0025] Preferably, the electrical conductivity of the slightly saline-alkali land in S2 is 4-8 dS / m, the electrical conductivity of the moderately saline-alkali land is 8-15 dS / m, and the electrical conductivity of the severely saline-alkali land is >15 dS / m.

[0026] Preferably, the saline-alkali land treatment mechanism of the adsorbent used in this invention is as follows:

[0027] The treatment mechanism of this invention is based on the core logic of rapid desalination and pH adjustment through chemical adsorption, sustained-release nutrition through microcapsules, and deep repair and consolidation through complex microbial communities. Each step is progressive and synergistic, forming a complete treatment closed loop. The specific process is as follows:

[0028] Firstly, the adsorbent employs a dual mechanism of "synergistic adsorption of anions and cations + pH adjustment through interlayer ion exchange." In this invention, the core carrier of the adsorbent is a complex of hydrogen-based bentonite and humic acid. The layered aluminosilicate framework of the hydrogen-based bentonite is interlayered with H+... + As a balancing ion, when the adsorbent is applied to saline-alkali land, the high concentration of Na in the soil solution... + Ca 2+ (The main salt-causing cations in saline-alkali soil) will react with the H in the hydrogen-based bentonite layer. + Interlayer ion exchange adsorption occurs: According to the principle of ion exchange equilibrium, higher concentrations of Na... + Ca 2+ It will preferentially occupy the interlayer adsorption sites, and the original H + The H released is replaced and released into the soil. + On the one hand, it can directly react with OH in the soil - A neutralization reaction occurs, rapidly lowering the local soil pH; on the other hand, H...+ Also can form weak acid environment with -COO - In humic acid, further buffer soil alkalinity; At the same time, the large amount of -COOH dissociated from humic acid retains -COO - , through electrostatic attraction to adsorb Na + , Ca 2+ In soil that does not participate in exchange; The protonation of the primary amino group activated by hydrochloric acid hydrolysis forms -NH3 + , then through electrostatic adsorption of Cl - , SO4 2- Anion, realize "anion and cation synergistic adsorption";

[0029] Secondly, in the present application, the microcapsules take vitamin B group and EDTA chelated trace elements as the core, and chitosan and sodium alginate as the wall material. When the microcapsules enter the saline-alkali soil with the adsorbent, the high pH of the soil will trigger the responsive hydrolysis of the wall material: OH - Competes with sodium alginate -COO - Binding Ca 2+ , destroying (-COO - )2Ca coordination bond; At the same time, the β-1,4 glycosidic bond of chitosan slowly breaks under alkaline conditions, so that the pore size of the wall material increases. This hydrolysis is slow and can control the release of nutrients, meeting the needs of the initial colonization of the bacterial population and adapting to the growth cycle of the bacterial population. The EDTA chelated trace elements can remain dissolved at pH, avoiding the formation of precipitates; The vitamin B group remains active, providing the bacterial population with essential coenzymes and cofactors for metabolism, and avoiding the interruption of repair caused by nutrient deficiency.

[0030] The complex bacterial population realizes deep repair through functional synergy. Lactobacillus plantarum (acid-producing bacteria) efficiently metabolizes to produce lactic acid and acetic acid under the assistance of vitamin B1 (thiamine, a coenzyme for sugar metabolism) and Fe 2+ (Cytochrome c oxidase component), further neutralizing OH - , and -COO - Exchange with Na + Promotes its eluviation; Bacillus megaterium (phosphorus solubilizing bacteria) enhances acid phosphatase activity under the assistance of vitamin B6 (pyridoxol, a coenzyme for transaminase) and Mn 2+ (Phosphatase activator), converting insoluble phosphorus into soluble PO4 3- , relieving phosphorus deficiency and assisting in salt reduction; Halomonas sp. (salt-tolerant bacteria) under the assistance of vitamin B12 (cobalamin, a coenzyme for methyl transfer) and Zn 2+With the support of DNA polymerase cofactors, compatible solutes (proline, betaine) are synthesized to enhance salt tolerance, and secreted extracellular polysaccharides (EPS) promote the formation of soil aggregates and provide colonization carriers for other bacteria. The three form a synergistic chain of "lowering pH → solubilizing phosphorus → maintaining structure → reducing salt content", which, together with the continuous effect of chemical adsorption, achieves the treatment goal.

[0031] This invention addresses two key issues in existing technologies regarding the treatment of saline-alkali land: "descending rebound of salt ions in the adsorbent" and "soil acidification due to excessively low pH levels."

[0032] The adsorbent relies on the interlayer H of hydrogen-based bentonite + humic acid-COO - Protonated primary amino group -NH3 + Adsorption of Na + Ca 2+ While salt ions are present, once adsorption reaches equilibrium, insufficient rinsing or water evaporation can lead to desorption and leakage of salt ions, which can damage the activity of the bacterial community and interrupt the repair process. At this point, the complex bacterial community is empowered by microcapsule nutrients; *Haloxylon ammodendron* secretes EPS to form a film that coats the adsorbent, reducing pore size and mitigating desorption; *Lactobacillus plantarum* produces acid, and *Bacillus megaterium* produces PO4 through phosphorus solubilization. 3- It can also react with the overflowing Ca 2+ The formation of insoluble salts fixes salt ions, which in turn inhibits their leakage; chemisorption and acid production by *Lactobacillus plantarum* easily lower the pH to below 7.0, while *Bacillus megaterium* relies on Mn... 2+ Vitamin B6 activates carbonic anhydrase, producing HCO3-. - In addition to neutralizing excess acidity, Haematopoietic bacteria can also consume organic acids, thus synergistically stabilizing pH.

[0033] In summary, in the initial stage: the adsorbent rapidly adsorbs salt ions, and the hydrogen-based bentonite exchanges H+. + The pH was initially lowered to create a basic environment for bacterial colonization.

[0034] Anti-rebound phase: Microcapsules release nutrient factors, enabling Halomonas bacteria to secrete EPS to encapsulate adsorbents and inhibit salt ion leakage; Lactobacillus plantarum and Bacillus megaterium metabolites fix the leaked salt, preventing soil electrical conductivity from rebounding;

[0035] Homeostasis maintenance phase: Nutrients released from the microcapsules enable Bacillus megaterium to produce HCO3. - Buffering acidity; Lactobacillus plantarum's acid production is self-limiting as pH decreases, while Halomonas consumes acid, together stabilizing the pH at the optimal environment for soil health;

[0036] Strengthen the repair stage: stable low salt, suitable pH environment, promote the reproduction of a large number of flora, lactobacillus plantarum further reduces alkali, bacillus megaterium decomposes phosphorus for fertilizer, halomonas improves soil structure, and the adsorption efficiency of the back-feeding chemical adsorbent is improved, and finally the long-term repair of the soil ecology is realized.

[0037] The beneficial effects of the application are:

[0038] 1. The application solves the problem of slow salt reduction and easy rebound in traditional technology through the synergistic mechanism of chemical adsorption and microbial repair. The core carrier of the adsorbent is a hydrogen-based bentonite-humic acid-amino grafted composite. By means of interlayer ion exchange and cationic and anionic electrostatic adsorption, Na + , Ca 2+ and other salt cations and Cl - , SO4 2- and other anions in the soil can be quickly captured, and the salinity is quickly reduced. At the same time, under the nutrition factor microcapsule empowerment, halomonas secretes exopolysaccharide to wrap the adsorbent to slow down desorption, and the metabolic products of lactobacillus plantarum and bacillus megaterium can fix the overflowed salt ions, forming an "adsorption-desorption prevention" closed loop to ensure the long-term stability of the soil salinity.

[0039] 2. The application effectively avoids the defects of traditional chemical improvement, such as easy acidification and pH rebound without intervention of sterile flora. After the interlayer H + exchange of hydrogen-based bentonite in the adsorbent is released, it can directly neutralize the soil OH - and build a weakly acidic buffer environment, initially reducing the high alkali pH to a suitable range. The subsequent complex flora forms a pH steady-state regulation system: bacillus megaterium secretes HCO3 - under the activation of nutrition factors to neutralize excess acidity, halomonas consumes excess organic acid, and lactobacillus plantarum produces acid and self-limits as the pH decreases, and the three work together to stabilize the soil pH in a healthy range conducive to plant growth and microbial colonization.

[0040] 3. The application breaks through the limitation of traditional technology, which only focuses on salt reduction and ignores the improvement of soil quality, and realizes the simultaneous promotion of governance and fertilization. The vitamin B family and EDTA chelated trace elements released by the nutrition factor microcapsule provide sustained power for microbial metabolism; the exopolysaccharide secreted by halomonas promotes the formation of soil aggregate structure and improves the hardening condition; bacillus megaterium converts insoluble phosphorus into available phosphorus, and humic acid directly supplements organic matter, significantly improving the soil cation exchange capacity. This process builds the foundation of soil ecological cycle, providing long-term support for subsequent plant growth and ecological repair.

[0041] 4. The application is designed for light, medium and heavy saline-alkali land characteristics, and the gradient dosage scheme does not need to adjust the core process to adapt to different regions of saline-alkali land such as coastal and inland irrigation areas, solving the problem of narrow application range of traditional technology. At the operation level, the steps of deep plowing, adsorbent spreading, leaching and the like are completed relying on conventional agricultural equipment, without the need for special instruments, reducing the application threshold. At the same time, chemical adsorption and microbial synergistic effect greatly reduce the leaching frequency, significantly saving water compared with physical leaching method, avoiding deep soil salt pollution, reducing the cost of treatment, and adapting to the needs of actual agricultural production. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with specific examples.

[0043] Preparation Example 1: A specific preparation method of an adsorbent for treating saline-alkali land, comprising the following steps:

[0044] (1) Select Lactobacillus plantarum, Sporosarcina luteola and Halomonas sp., respectively inoculate into culture medium, and carry out fermentation expansion to obtain strain fermentation liquor, resuspend the strain fermentation liquor with sterile normal saline to obtain a bacterial suspension with a concentration of 10 9 -10 10 CFU / mL, mix the bacterial suspension according to the weight ratio of Lactobacillus plantarum suspension, Sporosarcina luteola suspension and Halomonas sp. suspension 1:1:0.8 to obtain the complex bacterial population inoculant;

[0045] (2) Mix 100 g hydrogen bentonite, 20 g humic acid and 1.5 kg deionized water, stir at 30℃ for 20 min, then heat to 40℃ and continue to stir for 1 h, filter, wash and dry the obtained product, then crush it through a 100 mesh sieve to obtain an adsorbent carrier;

[0046] (3) Mix 100 g adsorbent carrier, 20 g N,N-dicyclohexyl carbodiimide, 3 g 4-dimethylpyridine and 1.5 kg anhydrous N,N-dimethylformamide, then add 8 g N-acetyl ethylenediamine, stir at room temperature for 5 h, centrifugal separation, wash and dry the product, then crush it through a 100 mesh sieve to obtain an adsorbent carrier containing acetyl groups;

[0047] (4) Mix 100 g adsorbent carrier containing acetyl groups with 300 g hydrochloric acid with a concentration of 10 mol / L, place it in a polytetrafluoroethylene reaction kettle, react at 80℃ for 8 h, cool to room temperature, centrifugal separation, wash the product with deionized water until the filtrate is neutral, dry and crush it through a 100 mesh sieve to obtain an adsorbent carrier containing amino groups;

[0048] (5) 5 g of vitamin B group (vitamin B1, vitamin B2, vitamin B6, vitamin B12 mixed in a weight ratio of 1:1:1:1), 5 g of EDTA chelated trace elements (EDTA chelated Fe 2+ , EDTA chelated Zn 2+ , EDTA chelated Mn 2+ mixed in a molar ratio of 2:2:1) are mixed with 40 g of deionized water to prepare a nutrient factor solution, and then mixed with 75 g of a 1% mass concentration chitosan aqueous solution after ultrasonic emulsification, 25 g of a 1% mass concentration sodium alginate aqueous solution is added dropwise, and 2.5 g of a 1 mol / L CaCl2 solution is added dropwise while stirring for 20 min, then filtered, and the product is washed, dried, and then mixed with 12.5 g of nutrient factor microcapsules, 100 g of an adsorbent carrier containing amino groups, and 1 kg of a complex microbial inoculum, stirred at 20°C for 1 h, and then filtered, and the product is dried to obtain an adsorbent for treating saline-alkali soil.

[0049] Preparation Example 2: A specific preparation method of the adsorbent for treating saline-alkali soil, comprising the following steps:

[0050] (1) Lactobacillus plantarum, Sporobacter termitum, and Halomonas sp. are selected and inoculated into culture media respectively for fermentation and expansion to obtain strain fermentation liquids, and the strain fermentation liquids are resuspended with sterile normal saline to obtain bacterial suspensions with a concentration of 10 9 -10 10 CFU / mL, and the bacterial suspensions are mixed in a weight ratio of 2:2:1 to obtain a complex microbial inoculum;

[0051] (2) 100 g of hydrogen-based bentonite, 30 g of humic acid, and 2 kg of deionized water are mixed, stirred at 35°C for 30 min, then heated to 45°C and continuously stirred for 2 h, filtered, and the obtained product is washed, dried, and then crushed to pass through a 100-mesh sieve to obtain an adsorbent carrier;

[0052] (3) 100 g of the adsorbent carrier, 25 g of N,N-dicyclohexyl carbodiimide, 4 g of 4-dimethylpyridine, and 2 kg of anhydrous N,N-dimethylformamide are mixed, and then 12 g of N-acetyl ethylenediamine is added, and the mixture is stirred at room temperature for 6 h, centrifuged, and the product is washed, dried, and then crushed to pass through a 100-mesh sieve to obtain an adsorbent carrier containing acetyl groups;

[0053] (4) 100 g of the adsorbent carrier containing acetyl groups is mixed with 500 g of hydrochloric acid with a concentration of 10 mol / L in a polytetrafluoroethylene reaction kettle, and reacted at 90°C for 10 h, then cooled to room temperature, centrifuged, and the product is washed with deionized water until the filtrate is neutral, dried, and then crushed to pass through a 100-mesh sieve to obtain an adsorbent carrier containing amino groups.

[0054] (5) 5 g of vitamin B group (vitamin B1, vitamin B2, vitamin B6, vitamin B12 mixed in a weight ratio of 1:1:1:1), 5 g of EDTA chelated trace elements (EDTA chelated Fe 2+ , EDTA chelated Zn 2+ , EDTA chelated Mn 2+ mixed in a molar ratio of 2:2:1) are mixed with 50 g of deionized water to prepare a nutrient factor solution, and then mixed with 120 g of a 2% chitosan aqueous solution, ultrasonically emulsified, 60 g of a 2% sodium alginate aqueous solution is added dropwise, 4.5 g of a 1 mol / L CaCl2 solution is added dropwise, stirred for 30 min, filtered, and the product is washed and dried to obtain nutrient factor microcapsules; 10 g of the nutrient factor microcapsules, 100 g of an adsorbent carrier containing amino groups, and 900 g of a compound microbial agent are mixed, stirred at 25°C for 1.5 h, and then filtered; the product is dried to obtain a chemical adsorbent for treating saline-alkali soil.

[0055] Preparation Example 3: A specific preparation method of the adsorbent for treating saline-alkali soil, comprising the following steps:

[0056] (1) Lactobacillus plantarum, Sporobacter termitum, and Halomonas sp. are selected and inoculated into culture medium respectively for fermentation and expansion to obtain strain fermentation liquor, and the strain fermentation liquor is resuspended with sterile normal saline to obtain a bacterial suspension with a concentration of 10 9 -10 10 CFU / mL, and the bacterial suspensions are mixed in a weight ratio of 3:3:1.2 to obtain the compound microbial agent;

[0057] (2) 100 g of hydrogen bentonite, 40 g of humic acid, and 2.5 kg of deionized water are mixed, stirred at 40°C for 40 min, then heated to 50°C and stirred for another 3 h, filtered, and the obtained product is washed, dried, and then crushed to pass through a 100-mesh sieve to obtain the adsorbent carrier;

[0058] (3) 100 g of the adsorbent carrier, 30 g of N,N-dicyclohexyl carbodiimide, 5 g of 4-dimethylpyridine, and 2.5 kg of anhydrous N,N-dimethylformamide are mixed, and then 16 g of N-acetyl ethylenediamine is added, and the mixture is stirred at room temperature for 7 h, centrifuged, and the obtained product is washed, dried, and then crushed to pass through a 100-mesh sieve to obtain the adsorbent carrier containing acetyl groups;

[0059] (4) 100 g of the acetyl-containing adsorbent carrier was mixed with 700 g of hydrochloric acid with a concentration of 10 mol / L in a polytetrafluoroethylene reactor, and reacted at 100 °C for 12 h. After cooling to room temperature, centrifugal separation was performed, and the product was washed with deionized water until the filtrate was neutral. After drying, the product was crushed to pass through a 100 mesh sieve to obtain the amino-containing adsorbent carrier;

[0060] (5) 5 g of vitamin B group (vitamin B1, vitamin B2, vitamin B6 and vitamin B12 were mixed in a weight ratio of 1:1:1:1), 5 g of EDTA chelated trace elements (EDTA chelated Fe 2+ , EDTA chelated Zn 2+ , and EDTA chelated Mn 2+ were mixed in a molar ratio of 2:2:1) were mixed with 60 g of deionized water to prepare a nutrient factor solution. Then, 175 g of a chitosan aqueous solution with a mass concentration of 3% was mixed, and ultrasonic emulsification was performed. Then, 105 g of a sodium alginate aqueous solution with a mass concentration of 3% was added dropwise, and 7 g of a CaCl2 solution with a concentration of 1 mol / L was added dropwise while stirring for 40 min. After filtration, the product was washed and dried to obtain nutrient factor microcapsules. Then, 8.33 g of the nutrient factor microcapsules, 100 g of the amino-containing adsorbent carrier and 833.33 g of the complex microbial consortium inoculum were mixed, stirred at 30 °C for 2 h, and then filtered. After drying, a chemical adsorbent for treating saline-alkali soil was obtained.

[0061] Comparative Preparation Example 1: Comparative Preparation Example 1 differs from Preparation Example 1 in that steps (2), (3) and (4) are omitted, and a hydrogen-containing bentonite is used instead of the amino-containing adsorbent carrier.

[0062] Comparative Preparation Example 2: Comparative Preparation Example 2 differs from Preparation Example 1 in that steps (3) and (4) are omitted, and the adsorbent carrier is not grafted with amino groups.

[0063] Comparative Preparation Example 3: Comparative Preparation Example 3 differs from Preparation Example 1 in that in step (5), 100 g of the amino-containing adsorbent carrier and 900 g of the complex microbial consortium inoculum are directly mixed, stirred at 25 °C for 1.5 h, and then filtered. After drying, a chemical adsorbent for treating saline-alkali soil is obtained.

[0064] Comparative Preparation Example 4: Comparative Preparation Example 4 differs from Preparation Example 2 in that the complex microbial consortium inoculum only contains a Lactobacillus plantarum suspension.

[0065] Example 1: A method for treating saline-alkali soil by chemical adsorption and microbial remediation, comprising the following steps:

[0066] S1. Select a mild saline-alkali land in the Yellow River Delta of Dongying City, Shandong Province, and deep plough the target saline-alkali land to a depth of 20-30 cm. The initial soil conductivity is 6.2 ds / m, the pH value is 8.8, and the percentage of exchangeable sodium is 12%.

[0067] S2. According to the initial salinity-alkalinity of the soil, the adsorbent prepared according to Preparation Example 1 for treating saline-alkali land is uniformly applied at a dosage of 30 kg per mu, and the adsorbent is fully mixed with the 0-20 cm soil layer by rotary ploughing, followed by irrigation with water at a volume of 50 m 3 per mu.

[0068] S3. First leaching is performed 7 days after application, with irrigation water at a volume of 80 m 3 per mu, and then the soil conductivity and pH value are monitored every 30 days. If the soil conductivity is > 5 dS / m or the pH is > 9.0, an additional leaching is performed with irrigation water at a volume of 60-80 m 3 per mu. When the soil conductivity is ≤ 3 dS / m and the pH is ≤ 8 for two consecutive monitoring, it is determined that the saline-alkali land treatment goal is reached, and the treatment of the saline-alkali land is completed.

[0069] Example 2: The difference between Example 2 and Example 1 is that in step S2, the adsorbent prepared according to Preparation Example 1 for treating saline-alkali land is uniformly applied at a dosage of 40 kg per mu, and the adsorbent is fully mixed with the 0-20 cm soil layer by rotary ploughing, followed by irrigation with water at a volume of 55 m 3 per mu. In step S3, the leaching irrigation water volume is 90 m 3 per mu.

[0070] Example 3: The difference between Example 3 and Example 1 is that in step S2, the adsorbent prepared according to Preparation Example 1 for treating saline-alkali land is uniformly applied at a dosage of 50 kg per mu, and the adsorbent is fully mixed with the 0-20 cm soil layer by rotary ploughing, followed by irrigation with water at a volume of 60 m 3 per mu. In step S3, the leaching irrigation water volume is 100 m 3 per mu.

[0071] Example 4: A saline-alkali land treatment method using chemical adsorption and microbial remediation, comprising the following steps:

[0072] S1. Select a moderate saline-alkali land in the Yellow River Delta of Dongying City, Shandong Province, and deep plough the target saline-alkali land to a depth of 20-30 cm. The initial soil conductivity is 6.2 ds / m, the pH value is 8.8, and the percentage of exchangeable sodium is 12%.

[0073] S2. According to the initial salinity of the soil, the adsorbent prepared according to Preparation Example 2 for the treatment of saline-alkali soil is uniformly applied at a dosage of 50 kg / mu, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the water irrigation amount is 50 m 3 / mu;

[0074] S3. First leaching is carried out 7 days after application, the leaching irrigation amount is 80 m 3 / mu, then the soil conductivity and pH value are monitored every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, additional leaching is carried out, the irrigation amount of additional leaching is 60-80 m 3 / mu; when the soil conductivity is continuously monitored for 2 times ≤ 3 dS / m and the pH is continuously monitored for 2 times ≤ 8, it is determined that the treatment goal of saline-alkali soil is reached, and the treatment of the saline-alkali soil is completed.

[0075] Example 5: The difference between Example 5 and Example 4 is that in step S2, the adsorbent prepared according to Preparation Example 2 for the treatment of saline-alkali soil is uniformly applied at a dosage of 65 kg / mu, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the water irrigation amount is 55 m 3 / mu; in step S3, the leaching irrigation amount is 90 m 3 / mu.

[0076] Example 6: The difference between Example 6 and Example 4 is that in step S2, the adsorbent prepared according to Preparation Example 2 for the treatment of saline-alkali soil is uniformly applied at a dosage of 80 kg / mu, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the water irrigation amount is 60 m 3 / mu; in step S3, the leaching irrigation amount is 100 m 3 / mu.

[0077] Example 7: A saline-alkali soil treatment method using chemical adsorption and microbial remediation, comprising the following steps:

[0078] S1. Select a heavy saline-alkali soil in Hetao Plain, Bayannur City, Inner Mongolia, deep tillage is carried out on the target saline-alkali soil, the deep tillage depth is 20-30 cm, the initial soil conductivity is 18.3 ds / m, the pH value is 9.6, and the percentage of exchangeable sodium is 25%;

[0079] S2. According to the initial salinity of the soil, the adsorbent prepared according to Preparation Example 3 for the treatment of saline-alkali soil is uniformly applied at a dosage of 80 kg / mu, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the water irrigation amount is 50 m 3 / mu;

[0080] S3. First leaching is carried out 7 days after application, the leaching irrigation amount is 80 m3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m 3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m

[0081] Example 8: The difference between Example 8 and Example 7 is that: in step S2, the adsorbent for treating saline-alkali soil prepared according to Preparation Example 3 is uniformly applied at a dosage of 90 kg / ha, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the irrigation amount is 55 m 3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m 3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m

[0082] Example 9: The difference between Example 9 and Example 7 is that: in step S2, the adsorbent for treating saline-alkali soil prepared according to Preparation Example 3 is uniformly applied at a dosage of 100 kg / ha, the adsorbent is fully mixed with the 0-20 cm soil layer by rotary tillage, and then water irrigation is carried out, the irrigation amount is 60 m 3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m 3 60-80 m3 / ha, then monitor the soil conductivity and pH value every 30 days, if the soil conductivity > 5 dS / m or the pH > 9.0, add 1 leaching, the irrigation amount of the added leaching is 60-80 m

[0083] Comparative Example 1: The difference between the comparative example and Example 3 is that: the adsorbent for treating saline-alkali soil prepared according to Preparation Example 1 in step S2 is replaced by the adsorbent for treating saline-alkali soil prepared according to Comparative Preparation Example 1.

[0084] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is that: the adsorbent for treating saline-alkali soil prepared according to Preparation Example 1 in step S2 is replaced by the adsorbent for treating saline-alkali soil prepared according to Comparative Preparation Example 2.

[0085] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is that: the adsorbent for treating saline-alkali soil prepared according to Preparation Example 1 in step S2 is replaced by the adsorbent for treating saline-alkali soil prepared according to Comparative Preparation Example 3.

[0086] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that: the adsorbent for treating saline-alkali soil prepared according to Preparation Example 1 in step S2 is replaced by the adsorbent for treating saline-alkali soil prepared according to Comparative Preparation Example 4.

[0087] Performance test:

[0088] 1. Salt ion desorption efficiency test: take each example and the soil sample of the comparative example "30 days after application", 50 g of each treatment is spread on a petri dish; then the petri dish is placed in a 30℃ constant temperature incubator, 2 mL of deionized water is added every day, and the treatment is continuously carried out for 7 days; then the treated soil sample is prepared into a test solution at a ratio of "water to soil 5:1", the salt ion concentration in the supernatant is determined by ion chromatography, and the desorption rate is calculated according to desorption rate = (total amount of salt ions in the solution after stress - total amount of salt ions in the solution before stress) / total adsorption amount of adsorbent x 100% (the total adsorption amount of the adsorbent is converted by the difference between the initial EC and the 30-day EC), and the experimental results are shown in Table 1.

[0089] 2. Activity of composite microbial agent: when testing, the viable count of the microbial flora is determined by plate counting method, 5 g of soil sample after 30 days of application of each example and comparative example is added into 45 mL of sterile normal saline, and a dilution liquid is prepared by shaking for 20 min, the diluted bacterial suspension is coated on the culture medium, and the number of colonies (CFU) is counted after incubation at 30℃ for 48 h to calculate the viable count of bacteria per gram of soil (CFU / g), and the experimental results are shown in Table 1.

[0090] 3. Soil structure and fertility index: when testing, the aggregate structure is determined by "wet sieving method", 100 g of air-dried soil sample of each example and comparative example is shaken in deionized water for 10 min using a nested sieve (2 mm, 0.25 mm), and the 0.25-2 mm particles are collected and dried to calculate the proportion; the organic matter is determined by "potassium dichromate oxidation-external heating method", the content is calculated by the oxidation-reduction reaction of potassium dichromate and organic matter; the soil cation exchange capacity CEC is determined by "ammonium acetate method", the soil cations are extracted by 1 mol / L ammonium acetate, and the CEC is calculated by distillation method, and the experimental results are shown in Table 1. +

[0091] 4. Treatment cycle record: the days from "application" to "first continuous 2 times to reach the standard" of each example and comparative example are recorded, and the total leaching water amount is calculated as the total irrigation amount (m 3 / mu) of all leaching (including additional leaching) during the period from the first leaching of S3 to reach the standard, and the experimental results are shown in Table 1.

[0092] Table 1 Performance test results

[0093]

[0094] Performance analysis:

[0095] From the experimental data in Table 1, it can be seen that the treatment schemes of examples 1-9 of the present application are significantly better than comparative examples 1-4 in terms of salt ion desorption control, salt-tolerant composite microbial flora activity maintenance, soil structure and fertility improvement, and treatment efficiency when treating different degrees of saline-alkali soil. ​

[0096] The core reason for the low salt ion desorption rate of the example is the construction of a double barrier of chemical strong adsorption and bacterial community desorption prevention: the adsorbent exchanges ions in the interlayer of hydrogen-based bentonite through hydrogen bonding, humic acid-COO - Electrostatic adsorption and protonated amino-NH3 + anion adsorption, realizing the synergistic and strong salt fixation of cations and anions; at the same time, the exopolysaccharide (EPS) secreted by the Halomonas sp. enabled by the nutrient factor microcapsule forms a film to wrap the adsorbent, slowing down the desorption channel, and the acid produced by Lactobacillus plantarum and the phosphorus-removing product of Bacillus megaterium can also form insoluble salt with the overflowing salt ions, further blocking the rebound; in comparison, Comparative Example 1 uses single hydrogen-based bentonite instead of the composite adsorbent, lacks the synergistic effect of the functional groups of humic acid adsorption and amino grafting, has limited adsorption capacity and no desorption inhibition at the structural level, and the desorption rate is significantly higher; the adsorbent of Comparative Example 2 is not grafted with amino groups, lacks anion adsorption sites, and the overall salt fixation capacity is weakened, so it is easily desorbed by environmental fluctuations after adsorption equilibrium, and the desorption rate is higher than that of the example; Comparative Example 3 omits the nutrient factor microcapsule, and the composite bacterial community lacks sufficient activity due to initial nutrient deficiency, so it cannot effectively secrete EPS and produce salt ion fixation products, and the desorption inhibition effect is weak, so the desorption rate is high; Comparative Example 4 contains only single Lactobacillus plantarum, lacks the physical wrapping of Halomonas sp. and the chemical fixation of Bacillus megaterium, and cannot form a desorption prevention synergistic chain, so the desorption rate is significantly higher than that of the example.

[0097] The key to the high number of viable bacteria in the example bacterial community is the triple guarantee of environmental adaptation, precise supply of nutrients, and bacterial community synergy: the adsorbent quickly reduces the salt content and adjusts the pH, creating an initial suitable environment for bacterial colonization; the chitosan-sodium alginate wall material of the nutrient factor microcapsule slowly hydrolyzes in alkaline soil, continuously releasing vitamin B (metabolic coenzyme) and EDTA chelated trace elements (enzyme activity activator), adapting to the growth cycle of the bacterial community; Lactobacillus plantarum, Bacillus megaterium, and Halomonas sp. form a functional complement, improving the overall colonization stability; single hydrogen-based bentonite of Comparative Example 1 has poor salt reduction and pH adjustment effect, and lacks the organic matter support of humic acid and the bacterial community attachment sites of amino grafting, so the soil microenvironment is not suitable for bacterial survival, and the number of viable bacteria is low; the adsorbent of Comparative Example 2 lacks amino grafting, resulting in insufficient salt fixation capacity, and the soil salinity and pH fluctuate greatly, making it difficult for the bacterial community to stably colonize, and the number of viable bacteria is lower than that of the example; Comparative Example 3 lacks nutrient factor microcapsules, and the bacterial community faces a deficiency of vitamins and trace elements in the early stage, hindering metabolism, and the colonization efficiency is low, so the number of viable bacteria is significantly lower than that of the example; Comparative Example 4 contains only Lactobacillus plantarum, lacks the synergistic effect of other bacterial communities, and lacks precise nutrient matching for single bacterial communities, so it is easily stressed in high-salt alkaline environments, and the number of viable bacteria is significantly lower.

[0098] The soil aggregate structure, organic matter content and cation exchange capacity (CEC) of the embodiment are significantly improved, which is due to the synergistic effect of physical modification, biological empowerment and fertilizer activation: the EPS secreted by halomonas sp. can bind soil particles, promoting the formation of 0.25-2mm aggregate structure; humic acid itself provides organic matter to the soil and can improve the soil colloidal properties; bacillus megaterium can efficiently solubilize phosphorus under the empowerment of nutrient factors, converting insoluble phosphorus into available phosphorus, and cooperating with the adsorbent to optimize the soil physicochemical properties, thus improving the fertility; in comparison, the single hydro-bentonite used in Comparative Example 1 has no structural modification effect of humic acid and biological empowerment of the microbial community, and cannot effectively promote the aggregation of aggregate structure, so the improvement of organic matter and CEC is limited, and the proportion of 0.25-2mm particles is low; in Comparative Example 2, the instability of salt fixation effect caused by the lack of amino grafting of the adsorbent affects the activity of the microbial community, the amount of EPS secreted by halomonas sp. is reduced, the improvement of aggregate structure is insufficient, and the improvement range of fertility indicators is lower than that of the embodiment; in Comparative Example 3, the activity of the microbial community is weak due to the lack of nutrient factor microcapsules, and the metabolic products (EPS, acid phosphatase, etc.) are insufficient, so the binding effect on soil structure and the activation effect on fertility are weak, and the related indicators are all low; in Comparative Example 4, only single lactobacillus is contained, lacking the structural modification function of halomonas sp. and the phosphorus solubilization and fertilizer supply function of bacillus megaterium, so the soil structure and fertility cannot be synergistically improved, and the indicators are not as good as those of the embodiment.

[0099] The embodiment has short treatment cycle and low water consumption, which benefits from the technical effects of rapid salt reduction and long-term salt control: the adsorbent realizes initial rapid salt reduction through ion exchange and electrostatic adsorption, reducing the initial leaching demand; the complex microbial community forms stable colonization under the support of nutrients, continuously inhibiting salt ion rebound, and reducing the frequency of additional leaching; the gradient dosage design for light, medium and heavy saline-alkali land further improves the treatment accuracy and efficiency; in comparison, the single adsorbent of Comparative Example 1 has slow salt reduction speed and frequent desorption rebound, so multiple additional leaching is needed to control salinity, resulting in prolonged treatment cycle and significantly higher water consumption; in Comparative Example 2, the lack of amino grafting of the adsorbent leads to insufficient salt fixation capacity, and the salt ion rebound speed is fast, so the leaching frequency needs to be increased to maintain the effect, resulting in longer treatment cycle and higher water consumption than the embodiment; in Comparative Example 3, the activity of the microbial community is low due to the lack of nutrient support, so it cannot quickly consolidate the salt reduction results, making it difficult to shorten the treatment cycle, and the leaching water consumption is not effectively controlled; in Comparative Example 4, the single microbial community has weak repair and salt control capacity, so it cannot form a long-term and stable treatment effect, and multiple leaching is needed to make up for the deficiency, resulting in long treatment cycle and high water consumption.

[0100] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing an adsorbent for treating saline-alkali land, characterized in that, Includes the following steps: (1) Select acid-producing bacteria, phosphate-solubilizing bacteria, and salt-tolerant functional bacteria, respectively, and inoculate them into the culture medium for fermentation and propagation to obtain the fermentation broth of each strain. Resuspend the fermentation broth of each strain in sterile physiological saline to obtain a concentration of 10. 9 -10 10 A CFU / mL bacterial suspension was prepared by mixing the bacterial suspension with acid-producing bacteria suspension, phosphate-solubilizing bacteria suspension, and salt-tolerant functional bacteria suspension in a weight ratio of 1-3:1-3:0.8-1.2 to obtain a compound bacterial agent. (2) Mix hydrogen-based bentonite, humic acid and deionized water, stir at 30-40℃ for 20-40 min, then heat to 40-50℃ and continue stirring for 1-3 h, filter, wash the obtained product, dry it and crush it through a 100-mesh sieve to obtain the adsorbent carrier. (3) The adsorbent carrier, N,N-dicyclohexylcarbodiimide, 4-dimethylpyridine and anhydrous N,N-dimethylformamide were mixed, and then N-acetylethylenediamine was added. The mixture was stirred at room temperature for 5-7 hours, centrifuged, and the product was washed, dried and pulverized through a 100-mesh sieve to obtain the adsorbent carrier containing acetyl groups. (4) The adsorbent carrier containing acetyl groups is mixed with hydrochloric acid with a concentration of 10 mol / L, placed in a polytetrafluoroethylene reactor, and reacted at a constant temperature of 80-100℃ for 8-12 h. After cooling to room temperature, the mixture is centrifuged and separated. The product is washed with deionized water until the pH of the filtrate is neutral. After drying, it is crushed and passed through a 100-mesh sieve to obtain an adsorbent carrier containing amino groups. (5) Prepare a nutrient factor solution by mixing B vitamins, EDTA chelated trace elements and deionized water, then mix it with a chitosan aqueous solution with a mass concentration of 1-3% and ultrasonically emulsify it. Add a sodium alginate aqueous solution with a mass concentration of 1-3% dropwise, and simultaneously add a CaCl2 solution with a concentration of 1mol / L. Stir and react for 20-40 minutes. Filter, wash and dry the product to obtain nutrient factor microcapsules. Mix the nutrient factor microcapsules, an adsorbent carrier containing amino groups and a compound bacterial agent, stir at 20-30℃ for 1-2 hours and filter. After drying the product, obtain an adsorbent for treating saline-alkali land.

2. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, In (1), acid-producing bacteria refer to Lactobacillus plantarum, phosphate-solubilizing bacteria refer to Bacillus megaterium, and salt-tolerant functional bacteria refer to halophilic bacteria.

3. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, In (2), the weight ratio of hydrogen-based bentonite, humic acid and deionized water is 1:0.2-0.4:15-25.

4. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, In (3), the adsorbent carrier, N,N-dicyclohexylcarbodiimide, 4-dimethylpyridine, anhydrous N,N-dimethylformamide and N-acetylethylenediamine are in a weight ratio of 1:0.2-0.3:0.03-0.05:15-25:0.08-0.

16.

5. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, The adsorbent carrier containing acetyl groups and hydrochloric acid with a concentration of 10 mol / L in (4) are in a weight ratio of 1:3-7.

6. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, In (5), the B vitamins, EDTA-chelated trace elements, and deionized water are in a weight ratio of 1:1:8-12; the nutrient factor solution, chitosan aqueous solution with a mass concentration of 1-3%, sodium alginate aqueous solution with a mass concentration of 1-3%, and CaCl2 solution with a concentration of 1 mol / L are in a weight ratio of 1:1.5-2.5:0.5-1.5:0.05-0.1; and the nutrient factor microcapsules, amino-containing adsorbent carrier, and compound bacterial agent are in a weight ratio of 1:8-12:80-100.

7. The method for preparing the adsorbent for treating saline-alkali land according to claim 1, characterized in that, In (5), the vitamin B group refers to a mixture of vitamin B1, vitamin B2, vitamin B6, and vitamin B12 in a weight ratio of 1:1:1:1; the EDTA chelated trace elements refer to EDTA chelated Fe. 2+ EDTA chelates Zn 2+ EDTA chelates Mn 2+ A mixture composed of a molar ratio of 2:2:

1.

8. A method for treating saline-alkali land using chemical adsorption and microbial remediation, comprising an adsorbent for treating saline-alkali land obtained by the preparation method according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Soil pretreatment: Deep tillage of the target saline-alkali land to a depth of 20-30cm was carried out, and the initial electrical conductivity, pH value and exchangeable sodium percentage of the soil were measured. S2. Based on the initial soil salinity, apply the adsorbent for treating saline-alkali land evenly at the following dosages: 30-50 kg / mu for mildly saline-alkali land, 50-80 kg / mu for moderately saline-alkali land, and 80-100 kg / mu for severely saline-alkali land. Thoroughly mix the adsorbent with the 0-20cm soil layer by rotary tillage, then irrigate with 50-60 ml of water. 3 / mu; S3. The first rinsing should be carried out on the 7th day after application, with a rinsing volume of 80-100m³. 3 / mu, then monitor soil electrical conductivity and pH every 30 days. If soil electrical conductivity >5dS / m or pH >9.0, perform an additional leaching, with an irrigation volume of 60-80m³. 3 / mu; when the soil electrical conductivity is ≤3dS / m for two consecutive monitoring sessions and the pH is ≤8 for two consecutive monitoring sessions, it is determined that the saline-alkali land treatment target has been achieved and the treatment of the saline-alkali land has been completed.

9. The method for treating saline-alkali land using chemical adsorption and microbial remediation according to claim 8, characterized in that, The electrical conductivity of the slightly saline-alkali land in S2 is 4-8 dS / m, that of the moderately saline-alkali land is 8-15 dS / m, and that of the severely saline-alkali land is >15 dS / m.

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