Soil remediation and reconstruction method in arid and semi-arid regions and application thereof

Abstract

The application discloses a kind of dry and semi-arid region soil remediation reconstruction method and application thereof, the application provides dry and semi-arid region soil remediation reconstruction method, comprising the following steps: S1, blue-green algae liquid is sprayed to concave earth surface, and culture solution is sprayed regularly to promote concave earth and blue algae combination;S2, phosphorite powder is doped in the mixed soil obtained in step S1 and inoculated phosphorus-solubilizing bacteria and arbuscular mycorrhizal fungi, to obtain composite soil;S3, host plant seed is sown in the composite soil and is planted.The application utilizes biological skin technology, especially the strong blue algae of resistance, the adsorption and water retention of concave earth are combined, and the organic phosphorus provided by phosphorite powder through phosphorus-solubilizing bacteria conversion effectively improves desertification soil.In addition, the symbiotic effect of arbuscular mycorrhizal fungi improves the drought resistance of plants, promotes water absorption, thereby improves soil water retention and plant survival rate, achieves the purpose of ecological restoration.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, specifically to a method for soil remediation and reconstruction in arid and semi-arid regions and its application. Background Technology

[0002] In arid and semi-arid regions, plant root growth faces severe environmental challenges. These areas suffer from low soil moisture content, poor water retention, and significant nutrient loss, leading to slow plant growth. Structural problems in the soil, such as compactness and poor aeration, limit root penetration and expansion, making it difficult for plants to access water and nutrients from deeper soil layers. Furthermore, uneven distribution of salts and nutrients in the soil further exacerbates the difficulties in root growth. Therefore, soil remediation in arid and semi-arid regions through soil modification and reconstruction is a promising area of ​​research. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for soil remediation and reconstruction in arid and semi-arid regions and its application.

[0004] The technical problem solved by this invention is achieved by the following technical solution.

[0005] This invention provides a method for soil remediation and reconstruction in arid and semi-arid regions, comprising the following steps:

[0006] S1. Spray the cyanobacterial solution onto the surface of the attapulgite, and spray the culture solution regularly to promote the combination of attapulgite and cyanobacterial.

[0007] S2. Phosphate rock powder is added to the mixed soil obtained in step S1 and phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi are inoculated to obtain composite soil.

[0008] S3. Sow host plant seeds in the composite soil for plant cultivation.

[0009] This invention also provides a method for soil remediation and reconstruction in arid and semi-arid regions, which reconstructs soil layers using a layered design approach, including the following steps:

[0010] S1. Use the original soil of the area to be restored as the base layer;

[0011] S2. Spray the cyanobacterial liquid onto the surface of the attapulgite, and spray the culture solution regularly to promote the combination of the attapulgite and the cyanobacterial to obtain mixed soil; mix the mixed soil with phosphate rock powder and inoculate it with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi to obtain composite soil; sow the host plant seeds in the composite soil and use them as the middle layer.

[0012] S3. The artificially expanded biological crust is evenly inoculated onto the surface of the composite soil as the top layer.

[0013] The present invention also provides an application of the above-mentioned soil remediation and reconstruction method in arid and semi-arid areas and in soil remediation in mining areas.

[0014] The present invention has the following beneficial effects:

[0015] This invention provides a method for soil remediation and reconstruction in arid and semi-arid regions and its application. The method includes: spraying cyanobacterial solution onto the surface of attapulgite soil; periodically spraying a culture solution to promote the bonding between the attapulgite soil and cyanobacteria; then mixing in phosphate rock powder and inoculating with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi to form a composite soil with good water retention. After sowing host plant seeds in the composite soil, the phosphorus required for plant growth is supplied by the phosphate-solubilizing bacteria through the decomposition of phosphate rock powder into organic phosphorus fertilizer. The water required for plant growth mainly relies on the absorption of soil moisture by the roots. Furthermore, after inoculation with arbuscular mycorrhizal fungi, the mycorrhizae formed by the plant roots and the fungi expand the contact area between the roots and the soil, promoting the absorption of water and nutrients by the plants. Ultimately, this method achieves the objectives of refining and homogenizing soil particle size, increasing the variety of microorganisms and nutrients in the soil, improving the soil's water retention capacity, and synergistic optimization of plant growth. This method features high soil water retention, low cost, simple process, strong stability, and environmental friendliness. It has strong technical guidance and practical engineering application significance for soil remediation and reconstruction in arid and semi-arid regions and ecological restoration in mining areas. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a comparison chart of the degree of cracking in the blank group in Embodiment 1 of the present invention;

[0018] Figure 2 This is a comparison diagram of the degree of cracking in the soil reconstruction group in Example 1 of the present invention;

[0019] Figure 3 This is a comparison chart of the moisture content of the blank group and the soil reconstruction group in Example 1 of the present invention;

[0020] Figure 4 This is a comparison chart of the germination rates of the blank group and the soil reconstructed group in Example 1 of the present invention;

[0021] Figure 5 This is a comparison chart of plant growth height between the blank group and the soil reconstruction group in Example 1 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] The following is a detailed description of a soil remediation and reconstruction method for arid and semi-arid regions and its application, provided by an embodiment of the present invention.

[0024] In a first aspect, embodiments of the present invention provide a method for soil remediation and reconstruction in arid and semi-arid regions, comprising the following steps:

[0025] S1. Spray the cyanobacterial solution onto the surface of the attapulgite, and spray the culture solution regularly to promote the combination of attapulgite and cyanobacterial.

[0026] S2. Phosphate rock powder is added to the mixed soil obtained in step S1 and phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi are inoculated to obtain composite soil.

[0027] S3. Sow host plant seeds in the composite soil for plant cultivation.

[0028] This invention provides a method for soil remediation and reconstruction in arid and semi-arid regions, comprising: utilizing the hydrophilicity and adsorption properties of attapulgite, spraying cyanobacterial liquid cultivated to the logarithmic growth phase onto the surface of the attapulgite to promote their bonding; incorporating phosphate rock powder into the mixed soil and inoculating it with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi. By combining cyanobacteria, attapulgite, phosphate rock powder, phosphate-solubilizing bacteria, and arbuscular mycorrhizal fungi, the method aims to refine and homogenize soil particle size, increase the variety of microorganisms and nutrients in the soil, improve soil water retention capacity, and synergistically optimize plant growth. Specifically:

[0029] Regional soil crusting plays a crucial role in soil stabilization and promoting soil cohesion. Biological crusts are classified into algal crusts, moss crusts, and lichen crusts. Algae are pioneer plants in deserts, especially highly resilient cyanobacteria, particularly filamentous cyanobacteria, which have a stronger colonization effect in soil. Attapulgite soil has strong adsorption capacity, good water retention, and good extensibility, and is widely used in agriculture, chemical catalysts, environmental protection, and pollution control. Phosphate rock contains abundant phosphorus, which can be directly used as a major source of phosphorus for plant growth through the action of phosphate-solubilizing bacteria. Mycorrhizal fungi are a major component of soil ecosystems, playing an important role in increasing plant nutrient absorption and enhancing plant adaptability. Arbuscular mycorrhizal fungi are a common type of soil fungus that can form a mutually beneficial symbiotic relationship with most terrestrial plants. By promoting root growth and development and optimizing root distribution, they facilitate plant utilization of deep soil moisture, providing strong support for the ecological restoration of soils in arid and semi-arid regions.

[0030] Secondly, embodiments of the present invention provide a method for soil remediation and reconstruction in arid and semi-arid regions, which reconstructs soil using a layered design approach, including the following steps:

[0031] Soil reconstruction using a layered design approach includes the following steps:

[0032] S1. Use the original soil of the area to be restored as the base layer;

[0033] S2. Spray the cyanobacterial liquid onto the surface of the attapulgite, and spray the culture solution regularly to promote the combination of the attapulgite and the cyanobacterial to obtain mixed soil; mix the mixed soil with phosphate rock powder and inoculate it with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi to obtain composite soil; sow the host plant seeds in the composite soil and use them as the middle layer.

[0034] S3. The artificially expanded biological crust is evenly inoculated onto the surface of the composite soil as the top layer.

[0035] This invention provides a method for soil remediation and reconstruction in arid and semi-arid regions. Addressing the problem of soil remediation and reconstruction in arid areas, the soil is reconstructed into three layers. The first layer is a surface layer, primarily composed of artificially expanded biocrusts. The second layer is a water-retaining layer, in which cyanobacteria are cultivated to promote their integration with attapulgite, phosphate rock powder is added, and phosphate-solubilizing bacteria are inoculated. Finally, arbuscular mycorrhizal fungi are inoculated to form a water-retaining composite soil. This composite soil composition is more easily combined with the artificially expanded biocrusts in the surface layer. This is because: cyanobacteria are rich in nitrogen, phosphorus, and potassium, which can be used directly as a nutrient source; attapulgite has a small particle size, fine texture, high specific surface area, and good adsorption capacity, making it more conducive to the formation of biocrusts with cyanobacteria. Phosphate rock is rich in phosphorus; after grinding, its surface area and solubility are further increased, making it easier for phosphate-solubilizing bacteria to utilize it. After grinding phosphate rock powder, it is mixed with attapulgite and cyanobacteria, and then inoculated with phosphate-solubilizing bacteria to further improve the utilization rate of phosphorus in the phosphate rock powder. Finally, arbuscular mycorrhizal fungi are inoculated into the composite soil, and host plant seeds are sown for planting. Arbuscular mycorrhizal fungi can improve soil structure, increase soil porosity, improve soil aeration and water retention capacity, and also enhance plant absorption of water and minerals, thereby improving the overall soil water retention rate and plant survival rate. The third layer is the sub-base, where the original soil samples from the area to be remediated are laid at the bottom of the top and middle layers in a certain proportion. The entire process, through a three-layer structure design of top, middle, and sub-base layers, achieves soil bonding, water retention, and nutrient supply functions, significantly improving the soil remediation effect. Furthermore, by utilizing bio-mineral composite technology combined with natural materials such as cyanobacteria, attapulgite, and phosphate rock, an environmentally friendly soil conditioner is developed, which is low-cost and produces no secondary pollution. This process is highly innovative, with high soil water retention and plant growth rates, low operating costs, and significant technological innovation and engineering feasibility.

[0036] In some alternative embodiments, the cyanobacterial solution is sprayed onto the surface of the attapulgite, and the culture medium is sprayed periodically to promote the combination of attapulgite and cyanobacteria. The culture conditions are as follows: the temperature of the light incubator is set at 20-30°C, the humidity is 60%, the light intensity is 2000 lux, the day / night cycle is 12h, and BG-11 culture medium is sprayed on the surface every 3-5 days for 14-21 days.

[0037] In some alternative embodiments, the cultivation conditions for sowing host plant seeds in the composite soil include: setting the temperature of the light incubator at 20-30°C, humidity at 60%, light intensity at 2000 lux, day / night cycle at 12h, spraying water on the surface every 3-5 days, and cultivating for 14-21 days.

[0038] In some alternative embodiments, the artificially expanded cultured biological crust is uniformly inoculated onto the surface of the composite soil at a ratio of 5%-10%, and the ratio of the original soil to the composite soil is 2-4:1.

[0039] In some optional embodiments, the artificially expanded biocrust is prepared by the following method: placing the biocrust taken from the area to be repaired in a culture dish, placing the culture dish in a light incubator, setting the temperature of the light incubator to 20-30℃, humidity to 60%, light intensity to 2000 lux, and day / night time to 12h / 12h, spraying BG-11 culture medium on the surface every 2-4 days, and incubating for 21-28 days.

[0040] In some alternative embodiments, the composite soil comprises the following components in parts by weight: 1-2 parts of cyanobacterial liquid, 90-180 parts of attapulgite, 5-10 parts of phosphate rock powder, 4-8 parts of phosphate-solubilizing bacteria, and 4-8 parts of arbuscular mycorrhizal fungi.

[0041] In some alternative embodiments, the cyanobacterial solution is prepared by the following method: cyanobacteria are placed in a culture medium for cultivation, and after centrifugation of the expanded algal solution that has grown to the logarithmic phase, the supernatant is removed, and the concentrated algal solution at the bottom is retained for later use.

[0042] In some alternative embodiments, the phosphate rock powder has a particle size of 200 mesh, and the attapulgite has a particle size of 400 mesh.

[0043] Thirdly, embodiments of the present invention also provide an application of the above-mentioned soil remediation and reconstruction method in arid and semi-arid areas and in soil remediation in mining areas.

[0044] The present invention will be further described below with reference to embodiments.

[0045] Comparative Example 1

[0046] I. Cultivation of Cyanobacteria and Preparation of Compound Soil

[0047] Cultivate cyanobacteria in an artificial climate incubator (temperature 25℃, humidity 60%). First, shake the *Micrococcus sheathingus* (purchased from the Algal Culture Bank of the Chinese Academy of Sciences) in the test tube well, then transfer it to an Erlenmeyer flask and culture under low light for 2-3 days. Set the artificial climate incubator to 25℃, light intensity 1000-2000 lux, and time 12h day / 12h night. Take 5-10 ml of the algal solution and add it to 10-20 ml of BG-11 medium, and culture for 20-30 days until biomass increases. Take 100-200 ml of the algal solution and transfer it to a centrifuge tube. Centrifuge at 1200 rpm for 5 minutes, remove the supernatant, and retain the algal solution at the bottom of the centrifuge tube for later use.

[0048] Place 1000-1500g of attapulgite in a round flowerpot (25cm high, 16cm in diameter). Spray the algal solution from the bottom of a centrifuge tube evenly onto the surface of the mixed soil. Place the culture dish in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night). Spray the surface of the attapulgite mixed with cyanobacteria with BG-11 culture solution every 3-5 days and culture for 14-21 days.

[0049] II. Planting

[0050] The plant used for sowing is *Leymus chinensis*. When filling the container with soil substrate, first fill it 2 / 3 full, then add the inoculant and mix thoroughly. Sow 40-50 plant seeds, then add the remaining 1 / 3 of the substrate and compact it. Place the pots in an artificial climate chamber at 20-30℃ and water 350-400ml per pot for 14-21 days to prepare the composite soil.

[0051] 3. Expand the culture of biological crust and add it to the water-retaining layer at 0-10cm as the surface layer.

[0052] The collected biocrust was placed in a round glass petri dish (10 cm in radius and 5 cm in height), and then placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12 hours day / 12 hours night). Every 2-4 days, the surface of the biocrust was evenly sprayed with BG-11 culture medium. The expanded cultured biocrust was then evenly inoculated onto the surface of the composite soil from step three at a ratio of 5%-10% as a top layer.

[0053] IV. Mix in deep soil from a depth of 10-20cm.

[0054] The original soil collected from the experimental area was used as the bottom layer. The ratio of the original soil to the composite soil in step three was 3:1. The original soil was placed at the bottom of the composite soil and then placed in a round flowerpot (30cm high and 22cm in diameter). The flowerpot was placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12 hours day / 12 hours night) for cultivation. The watering volume was 350-400ml / pot. The soil was cultivated for 7-14 days until it was successfully mixed. This soil was called the soil reconstruction group.

[0055] After culturing the soil reconstructed group for 14-21 days, none of the sown seeds germinated, indicating that the nutrients in the biological crust and the cyanobacteria mixed with the soil were limited and insufficient to support plant rooting and germination. Therefore, nutrients should be added to the mixed soil.

[0056] Comparative Example 2

[0057] I. Cultivation of Cyanobacteria and Preparation of Compound Soil

[0058] Cultivate cyanobacteria in an artificial climate incubator (temperature 25℃, humidity 60%). First, shake the *Micrococcus sheathingus* (purchased from the Algal Culture Bank of the Chinese Academy of Sciences) in the test tube well, then transfer it to an Erlenmeyer flask and culture under low light for 2-3 days. Set the artificial climate incubator to 25℃, light intensity 1000-2000 lux, and time 12h day / 12h night. Take 5-10 ml of the algal solution and add it to 10-20 ml of BG-11 medium, and culture for 20-30 days until biomass increases. Take 100-200 ml of the algal solution and transfer it to a centrifuge tube. Centrifuge at 1200 rpm for 5 minutes, remove the supernatant, and retain the algal solution at the bottom of the centrifuge tube for later use.

[0059] Place 1000-1500g of attapulgite and 50-75g of phosphate rock powder (ground into a 200-mesh sieve using a mill) in a round flowerpot (25cm high, 16cm in diameter). Spray the algal solution from the bottom of a centrifuge tube evenly onto the surface of the mixed soil. Place the culture dish in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night). Spray the surface of the mixed soil with BG-11 culture solution every 3-5 days and culture for 14-21 days.

[0060] II. Inoculation with phosphate-solubilizing bacteria

[0061] Dissolve 1-2g of Bacillus megaterium powder in 700-1400g of pure water and shake well. Spray evenly onto the surface of the mixed soil from step one and incubate for 7-14 days to use as a composite soil substrate.

[0062] III. Planting

[0063] The plant used for sowing is *Leymus chinensis*. When filling the container with soil substrate, first fill it 2 / 3 full, then add the inoculant and mix thoroughly. Sow 40-50 plant seeds, then add the remaining 1 / 3 of the substrate and compact it. Place the pots in an artificial climate chamber at 20-30℃ and water 350-400ml per pot for 14-21 days to prepare the composite soil.

[0064] IV. Expand the culture of biological crust and add it to the water-retaining layer at 0-10cm as a surface layer.

[0065] The collected biocrust was placed in a round glass petri dish (10cm radius, 5cm height) and then placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night). Every 2-4 days, the surface of the biocrust was evenly sprayed with BG-11 culture medium. The expanded cultured biocrust was then evenly inoculated onto the surface of the composite soil from step three at a ratio of 5%-10% as a top layer.

[0066] 5. Mix in soil from a depth of 10-20cm.

[0067] The original soil collected from the experimental area was used as the bottom layer. The ratio of the original soil to the composite soil in step four was 3:1. The original soil was placed at the bottom of the composite soil and then placed in a round flowerpot (30cm high and 22cm in diameter). The flowerpot was placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12 hours day / 12 hours night) for cultivation. The watering volume was 350-400ml / pot. The soil was cultivated for 7-14 days until it was successfully mixed. This soil was called the soil reconstruction group.

[0068] After culturing the soil reconstructed group for 14-21 days, 80% of the sown seeds were non-germinating, and among the germinated seeds, the root length and growth height of the plants were generally low. Since insufficient nutrients, especially phosphorus, reduce plant growth rate and height, it indicates that phosphate-solubilizing bacteria cannot effectively utilize phosphorus from phosphate rock powder. Therefore, microorganisms that can synergistically interact with phosphate-solubilizing bacteria and increase the plant's absorption of nutrients from the soil should be added to the mixed soil.

[0069] Example 1

[0070] I. Cultivation of Cyanobacteria and Preparation of Compound Soil

[0071] Cultivate cyanobacteria in an artificial climate incubator (temperature 25℃, humidity 60%). First, shake the *Micrococcus sheathingans* (purchased from the Algal Culture Bank of the Chinese Academy of Sciences) in the test tube well, then transfer it to an Erlenmeyer flask and culture under low light for 2-3 days. Set the artificial climate incubator to 25℃, light intensity 1000-2000 lux, and time 12 hours day / 12 hours night. Add 5-10 ml of the algal solution to 10-20 ml of BG-11 medium and culture for 20-30 days until biomass increases. Transfer 100-200 ml of the algal solution to a centrifuge tube and centrifuge (1200 rpm) for 5 minutes. Remove the supernatant, retaining the algal solution at the bottom of the centrifuge tube for later use.

[0072] Place 1000-1500g of attapulgite and 50-75g of phosphate rock powder (ground into a 200-mesh sieve using a mill) in a round flowerpot (25cm high, 16cm in diameter). Spray the algal solution from the bottom of a centrifuge tube evenly onto the surface of the mixed soil. Place the culture dish in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night). Spray the surface of the mixed soil with BG-11 culture solution every 3-5 days and culture for 14-21 days.

[0073] II. Inoculation with phosphate-solubilizing bacteria

[0074] Dissolve 1-2g of Bacillus megaterium powder in 700-1400g of pure water and shake well. Spray evenly onto the surface of the mixed soil from step one and incubate for 7-14 days to use as a composite soil substrate.

[0075] III. Planting and Inoculation with Arbuscular Mycorrhizal Fungi

[0076] Arbuscular mycorrhizal fungi (Aureobasidium mosesense) are selected, and the plant used for sowing is *Leymus chinensis*. Since the arbuscular mycorrhizal fungi and the plant need to form a symbiotic relationship, both should be inoculated simultaneously. When preparing the composite soil substrate, first fill the container to 2 / 3 full, then add the inoculum and mix thoroughly. Sow 40-50 plant seeds, then add the remaining 1 / 3 of the substrate and compact it. Place the pots in an artificial climate chamber at 20-30℃ and water 350-400 ml per pot for 14-21 days to prepare the composite soil.

[0077] IV. Expand the culture of biological crust and add it to the water-retaining layer at 0-10cm as a surface layer.

[0078] The collected biocrust was placed in a round glass petri dish (10cm radius, 5cm height) and then placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night). Every 2-4 days, the surface of the biocrust was evenly sprayed with BG-11 culture medium. The expanded cultured biocrust was then evenly inoculated onto the surface of the composite soil from step three at a ratio of 5%-10% as a top layer.

[0079] 5. Mix in soil from a depth of 10-20cm.

[0080] The original soil collected from the experimental area was used as the bottom layer. The ratio of the original soil to the composite soil in step four was 3:1. The original soil was placed at the bottom of the composite soil and then placed in a round flowerpot (30cm high and 22cm in diameter). The flowerpot was placed in an artificial climate chamber (temperature 25℃, humidity 60%, light intensity 2000 lux, time setting 12h day / 12h night) for cultivation. The watering volume was 350-400ml / pot. The soil was cultivated for 7-14 days until it was successfully mixed. This soil was called the soil reconstruction group.

[0081] Figure 1 and Figure 2 In this study, the blank control group and the soil reconstruction group from Example 1 were placed under the same temperature, humidity, and light intensity for cultivation, with a watering volume of 300-400 ml for each group. After 14-21 days of cultivation, the soil samples could be obtained from... Figure 1 The study observed an increase in soil cracking in the control group. Figure 1 The left image is a photo taken 3 days after culture, and the right image is a photo taken 14 days after culture. Figure 2 It can be seen that the degree of soil cracking in the soil remodeling group is significantly reduced. Figure 2 (The left image is a photo taken after 3 days of cultivation, and the right image is a photo taken after 14 days of cultivation.) This demonstrates that the soil remodeling group can effectively reduce the degree of soil cracking.

[0082] Figure 3 In this study, the control group (original soil from the experimental area) and the soil reconstructed group were placed under the same temperature, humidity, and light intensity for cultivation, with each group receiving 300-400 ml of water. From the start of cultivation, the moisture content of the control group decreased steadily over time, decreasing from 41.22% to 4.31% within two weeks. The moisture content of the soil reconstructed group initially decreased and then stabilized, decreasing from 47.31% on the first day to 39.16% on the seventh day before remaining stable. This indicates that the soil reconstructed group had a higher soil water retention rate.

[0083] Figure 4 In this study, 50 *Elymus sibiricum* seeds were sown in both the control group and the soil reconstructed group, and cultured under the same temperature, humidity, and light intensity, with each group receiving 300-400 ml of water. Both groups germinated on the fifth day. After 21 days of culture, the germination rate in the control group reached 46%, while the germination rate in the soil reconstructed group reached 70%. This indicates that the soil in the soil reconstructed group was more conducive to the germination and growth of *Elymus sibiricum* seeds.

[0084] Figure 5In this study, the average growth height of *Elymus sibiricum* was recorded daily during its germination and growth. In the control group, the average plant height increased from 1 cm on day 5 to 15 cm on day 19, after which the plant height remained unchanged. In the soil reconstructed group, the average plant height increased from 3 cm on day 5 to 27 cm on day 19, after which the plant height remained unchanged. This indicates that the soil in the soil reconstructed group was more nutrient-rich, which was more conducive to plant growth.

[0085] As can be seen from the above experimental examples, this invention provides a method for soil remediation and reconstruction in arid and semi-arid regions, addressing the issue of soil remediation and reconstruction in these areas. This method integrates the cultivation of cyanobacteria, the cultivation of biocrusts, and the compounding of biocrusts, attapulgite soil, native soil, and phosphate rock powder, along with inoculation with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi to improve soil water retention and plant growth. Attapulgite soil, with its high specific surface area, excellent adsorption properties, and good water storage capacity, is chosen to facilitate the compounding of cyanobacteria and attapulgite soil, thereby enhancing plant water absorption. The high surface area and solubility of phosphate rock powder make it easier for phosphate-solubilizing bacteria to utilize. Through symbiotic interaction with phosphate-solubilizing bacteria, phosphate rock powder can be biologically converted into organic phosphorus fertilizer that is easily utilized by plants, thus providing the phosphorus element required by the plants. Plants rely primarily on their roots to absorb water from the soil. Inoculation with arbuscular mycorrhizal fungi expands the contact area between the roots and the soil by forming mycorrhizae. The resulting hyphae have the ability to absorb and transport water, enabling them to absorb water from areas inaccessible to plant roots. This promotes water absorption by plants and achieves the goals of soil remediation and reconstruction in arid and semi-arid regions as well as ecological restoration in mining areas.

[0086] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for soil remediation and reconstruction in arid and semi-arid regions, characterized in that, Soil reconstruction using a layered design approach includes the following steps: S1. Use the original soil of the area to be restored as the base layer; S2. Spray the cyanobacterial liquid onto the surface of the attapulgite, and spray the culture solution regularly to promote the combination of the attapulgite and the cyanobacterial to obtain mixed soil; mix the mixed soil with phosphate rock powder and inoculate it with phosphate-solubilizing bacteria and arbuscular mycorrhizal fungi to obtain composite soil; sow the host plant seeds in the composite soil and use them as the middle layer. S3. The artificially expanded cultured biological crust is evenly inoculated onto the surface of the composite soil as a top layer.

2. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 1, characterized in that, The cyanobacterial solution was sprayed onto the surface of the attapulgite, and the culture medium was sprayed regularly to promote the combination of attapulgite and cyanobacteria. The culture conditions were as follows: the temperature of the light incubator was 20-30℃, the humidity was 60%, the light intensity was 2000 lux, and the day / night cycle was 12h. BG-11 culture medium was sprayed on the surface every 3-5 days, and the culture was carried out for 14-21 days.

3. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 1, characterized in that, The cultivation conditions for sowing host plant seeds in the composite soil include: setting the temperature of the light incubator at 20-30℃, humidity at 60%, light intensity at 2000 lux, day / night cycle at 12h, spraying water on the surface every 3-5 days, and cultivating for 14-21 days.

4. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 1, characterized in that, The artificially expanded cultured biological crust is uniformly inoculated onto the surface of the composite soil at a ratio of 5%-10%, and the ratio of the original soil to the composite soil is 2-4:

1.

5. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 4, characterized in that, The artificially expanded cultured biocrust was prepared by the following method: the biocrust taken from the area to be repaired was placed in a culture dish, the culture dish was placed in a light incubator, the temperature of the light incubator was set to 20-30℃, humidity to 60%, light intensity to 2000 lux, and day / night time to 12h day / 12h night, and BG-11 culture medium was sprayed on the surface every 2-4 days, and cultured for 21-28 days.

6. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 1, characterized in that, The composite soil comprises the following components in parts by weight: 1-2 parts of cyanobacterial liquid, 90-180 parts of attapulgite, 5-10 parts of phosphate rock powder, 4-8 parts of phosphate-solubilizing bacteria, and 4-8 parts of arbuscular mycorrhizal fungi.

7. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 6, characterized in that, The cyanobacterial solution is prepared by the following method: cyanobacteria are placed in a culture medium for cultivation, and after centrifugation of the expanded algal solution that has grown to the logarithmic phase, the supernatant is removed, and the concentrated algal solution at the bottom is retained for later use.

8. The soil remediation and reconstruction method for arid and semi-arid regions according to claim 6, characterized in that, The phosphate rock powder has a particle size of 200 mesh, and the attapulgite has a particle size of 400 mesh.

9. The application of the soil remediation and reconstruction method for arid and semi-arid areas according to any one of claims 1-8 in soil remediation in arid and semi-arid areas and mining areas.

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