Method for improving water and soil loss through microorganisms

Abstract

According to the method, bacillus licheniformis bacterial liquid and calcium ion liquid are sequentially, slowly and evenly sprayed on the surface of a soil body, soil particles on the surface of a slope are cemented, a layer of calcium carbonate protection film is formed on the surface of the soil body, the anti-scouring capacity of the soil body can be effectively improved, flowing of the soil particles is reduced, and plant growth is protected; the adopted bacillus licheniformis can also increase the number of effective microbial communities in soil, improve the root system environment, promote plant growth, inhibit reproduction of harmful microorganisms, improve the granular structure of the soil, improve the soil, regulate the pH value of the soil, improve the water storage, energy storage and heat preservation of the soil, improve the disease resistance of crops and promote the maturity of plants; after vegetation grows, the effect of water and soil conservation can be improved, generated calcium carbonate can also bond soil particles, water and soil loss is reduced, bacillus licheniformis plays a dual role, multiple utilization of resources is achieved, and wide application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the intersecting field of water conservancy engineering and microbial engineering, and in particular relates to a method for improving soil and water loss by using microorganisms. Background Art

[0002] Soil erosion refers to the phenomenon that due to the influence of natural or human factors, rainwater cannot be absorbed locally, flows down and washes the soil, causing the loss of water and soil at the same time. The main reasons are large ground slope, improper land use, destruction of ground vegetation, unreasonable farming technology, loose soil, deforestation, overgrazing, etc. The hazards of soil erosion are mainly manifested in: the soil cultivation layer is eroded and destroyed, making the soil fertility increasingly exhausted; silting up rivers, channels, and reservoirs, reducing the benefits of water conservancy projects, and even causing water and drought disasters, seriously affecting industrial and agricultural production; soil erosion poses a serious threat to agricultural production in mountainous areas and downstream rivers. The Loess Plateau is one of the key areas for soil and water erosion control in China. Therefore, it is of great scientific and practical significance to carry out research on soil and water erosion control methods and measures.

[0003] At present, there are many engineering measures for soil and water loss control, which can be summarized into three categories: the first is to build various engineering measures, including slope control projects, ditch control projects and small water conservancy projects; the second is biological measures, including afforestation, grass cultivation, etc.; the third is water storage and soil conservation, which refers to technical measures to change the micro-topography of the slope, improve the soil, and improve agricultural production, and conserve soil and water. Although each measure can achieve good control effects, there are still some disadvantages. Among them, the cost of engineering measures is too high, requiring a lot of manpower and material resources, and may also change the original terrain and cause natural disasters; plant measures require time to maintain, and when encountering strong rainfall, they will wash away the soil surface, affecting the survival rate and life of plants. The vegetation coverage period is long. When encountering heavy rainfall weather, the slope surface will be washed and eroded by rainwater, and the shallowly buried plant roots will quickly expose the surface, which may eventually cause the death of vegetation; water storage and soil conservation will change the slope terrain, requiring certain agricultural production technical means, and it is difficult to cover a large area. Therefore, exploring a new, efficient, economical and environmentally friendly method for slope soil erosion control has become an urgent problem to be solved.

[0004] In recent years, a technology based on microbial induced calcium carbonate deposition (MICP) has set off a research boom in the field of geotechnical engineering. The principle of this technology is mainly to use urease produced by urease-producing microorganisms to catalyze the hydrolysis of urea to produce CO3 2- ,CO3 2- Then with the Ca in the environment 2+ Combined to form calcium carbonate precipitate:

[0005] CO(NH2)2+H2O+GaCl2→2NH3+GaCO3↓+2Cl -

[0006] However, in the process of calcium carbonate precipitation induced by urea hydrolyzing bacteria, secondary products such as ammonium ions and chloride ions are generated, causing soil compaction and acidification. The ammonia generated by urease-producing bacteria is highly soluble in water and reacts with water to generate OH - and NH4 + , which changes the pH of the soil and destroys the nitrogen balance. As the number of reinforcements increases, it has a greater impact on the slope soil environment.

[0007] MICP technology has made great progress in the field of geotechnical engineering, but there are no reports on the use of microbial technology to control soil erosion on slopes at home and abroad.

[0008] The prior art with publication number CN113882407A discloses a landslide prevention and control method based on microbial mineralization. The microbial bacterial liquid used in this method is a culture solution of urease-producing bacteria, and the urease-producing bacteria is Bacillus pasteurii. The MICP technology is applied to the solidification of the soil surface and the potential sliding surface. The surface spraying method is used to solidify the soil surface, block the cracks on the soil surface, reduce the infiltration of surface water, prevent the softening and dissolution decomposition of the rock and soil body, and strengthen the surface soil body. Through the splitting grouting and penetration grouting methods, microbial bacterial liquid and cementing liquid are injected into the potential sliding surface of the soil body in turn, in order to solidify the potential sliding surface, replacing the traditional chemical slurry solidification. The MICP technology is also used to solidify sand soil to obtain sand anti-slide piles, sand lattices, sand drainage ditches and intercepting ditches, so as to achieve the purpose of stabilizing the slope and drainage. However, the reaction of Bacillus pasteurii will also change the original pH of the soil, destroy the nitrogen balance, and affect the growth of plants on the soil. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for improving soil and water loss by using microorganisms.

[0010] The microbial method for improving soil erosion comprises the following steps:

[0011] Step 1: The plant seeds are germinated and sprayed on the slope using hydraulic spraying technology;

[0012] Step 2: Setting a lattice structure on the surface of the rock slope, filling the lattice structure with soil and then planting plants;

[0013] Step 3: Calculate the scouring force of the slope surface water flow based on the regional rainfall intensity, slope area, slope angle and slope length data, and determine the number of microbial reinforcements based on the cementation force and calcium carbonate precipitation generated by microbial mineralization;

[0014] Step 4: According to the reinforcement times determined in step 3, a cementing liquid obtained by mixing Bacillus licheniformis solution and calcium propionate solution is sprayed on the slope surface and the lattice.

[0015] Preferably, in step 4, the concentration of the Bacillus licheniformis solution is 0.1 mol / L to 1.0 mol / L, the concentration of the calcium propionate solution is 0.5 mol / L to 1.5 mol / L, and the volume ratio of the Bacillus licheniformis solution to the calcium propionate solution in the binder is 1:5 to 1:1.

[0016] Preferably, in step 3, the calculation method of the number of microbial reinforcement times n is:

[0017] a(1+b) n =W(ρμ 1x μ 1y -1 -ρμ 2x μ 2y -1 )L -1

[0018] Where: a is the original soil cohesion, n is the number of times the cementing fluid is sprayed, b represents the percentage of the cohesion between soil particles increased after each reinforcement; W represents the scour coefficient, ρ is the density of slope soil particles, μ 1x and μ 1y are the lateral and longitudinal shear stresses of the water flow at the toe of the slope, μ 2x and μ 2y are the lateral and longitudinal shear stresses of water flow at the top of the slope, respectively, and L is the length of the slope.

[0019] Preferably, in step 4, the single spraying amount Q of the cementing liquid is:

[0020] Q=(a+b)[(A×d) / n] / c

[0021] A is the slope area; d is the mass of Bacillus licheniformis sprayed per unit area each time; n is the molecular weight of Bacillus licheniformis, c is the concentration of Bacillus licheniformis solution, a and b represent the volume ratio of Bacillus licheniformis solution to calcium ion solution, respectively, where a=1.

[0022] Preferably, in step 4, the concentration of the Bacillus licheniformis solution is 0.5 mol / L, the concentration of the calcium propionate solution is 1.0 mol / L, and the volume ratio of the Bacillus licheniformis solution to the calcium propionate solution in the binder is 1:4.

[0023] Preferably, in step four, a cementing solution obtained by mixing a Bacillus licheniformis solution and a calcium propionate solution is infiltrated into the slope by a grouting method.

[0024] Preferably, in step 2, the lattice is rectangular, the lattice beams have a lateral spacing of 2.5 to 3.0 m, and the lattice beams have a vertical spacing of 3.5 to 4.5 m; the lattice is anchored to the surface of the rock slope by anchor rods or anchor cables.

[0025] Preferably, when the slope is an earth slope, in step 2, plants are directly planted on the slope surface, the plants cover the entire slope surface, and drainage ditches are set in the earth slope. In step 4, the drainage ditches are also sprayed with binder liquid.

[0026] The beneficial effects of the present invention are:

[0027] 1) The present invention sprays Bacillus licheniformis liquid and calcium ion liquid on the soil surface in sequence and slowly and evenly to cement the soil particles on the slope surface, so that a layer of calcium carbonate protective film is formed on the soil surface, which can effectively improve the soil's anti-scouring ability, reduce the flow of soil particles, and protect plant growth; the Bacillus licheniformis used can also increase the number of beneficial bacteria in the soil, improve the root environment, promote plant growth and inhibit the reproduction of harmful microorganisms, improve the soil aggregate structure, improve the soil, adjust the soil pH, improve the soil water storage, energy storage and heat preservation, improve the disease resistance of crops, promote plant growth and maturity, and improve the effect of soil and water conservation after vegetation growth. The generated calcium carbonate can also cement soil particles and reduce soil and water loss. The Bacillus licheniformis plays a dual role and realizes the multiple utilization of resources.

[0028] 2) The calcium carbonate precipitate induced by the present invention using Bacillus licheniformis is stable in nature, has good mechanical properties, strong durability, and can quickly cement soil particles. At the same time, Bacillus licheniformis can also improve soil water storage and energy storage, improve crop disease resistance, inhibit the reproduction and invasion of soil pathogens, reduce diseases, prevent insect pests from breaking out, reduce various fungal diseases, and promote crop growth and maturity. Finally, the calcium carbonate precipitate generated by Bacillus licheniformis is also beneficial to the slope protection project of the drainage ditch, which has the advantages of economy, environmental protection, high efficiency and controllability compared to traditional concrete slope protection. The Bacillus licheniformis on the surface of the slope will flow to the crops with the water flow, which is very beneficial to the crops at the corners of the slope. Compared with existing control measures, microbial technology has advantages in many aspects such as ecological protection, efficiency, and economy, can produce very significant effects, and has broad application prospects.

[0029] 3) The present invention adopts hydraulic seeding technology. Hydraulic seeding has the characteristics of high mechanization and can quickly plant grass over a large area. Different plants can be selected for mixed seeding according to specific natural conditions or design requirements to complement the advantages of different plants, thereby increasing the feasibility of practical engineering applications. The growth of plants not only increases the erosion resistance and skid resistance of the slope, but also effectively reduces the risk of soil and water loss on the slope. The root system of the plant can firmly grasp the soil particles to form a natural fixed layer, providing additional support for the slope and reducing erosion and denudation of the slope. The root system of the plant takes root and expands in the soil to form a complex root network, which helps to enhance the structure and cohesion of the soil, reduce soil erosion and soil loss, and improve the skid resistance of the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of soil erosion control on soil slopes due to microbial mineralization

[0031] Figure 2 Schematic diagram of soil erosion control on rock slopes due to microbial mineralization

[0032] Figure 3 Schematic diagram of drainage ditch slope protection

[0033] Explanation of the reference numerals: soil slope 1, Bacillus licheniformis mineralized soil layer 2, plant 3, rock slope 4, lattice beam 5, anchor rod or anchor cable 6, drainage ditch 7, drainage ditch microbial mineralized slope protection 8. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0035] Embodiment 1

[0036] As an embodiment, this microbial method for improving soil erosion is aimed at the impact of the secondary products of the commonly used urease-producing bacteria Bacillus subtilis on the environment, the high maintenance cost of traditional biological measures and the problem that shallow vegetation roots are easily eroded. The present invention provides a new type of microorganism, which uses the mineralization effect of Bacillus licheniformis to control soil erosion, combines MICP technology with biological measures, covers the surface of soil slopes with vegetation, and sets up grids for rock slopes, fills the grids with soil and plants vegetation. The cementing liquid in the MICP is sprayed onto the surface of the slope soil and the rock slope grid to cement the soil particles, thereby enhancing the slope's anti-erosion ability, reducing the runoff reduction rate, weakening the impact of surface runoff, preventing shallow buried plant roots from quickly exposing to the ground, reducing maintenance costs, improving plant survival, promoting root growth, and using plant roots and calcium carbonate precipitation produced by mineralization to fix soil particles, in order to slow down the loss rate of soil particles and achieve the purpose of soil and water conservation. Specifically, the following steps are included:

[0037] Step 1: The plant seeds are germinated and sprayed on the slope using hydraulic spraying technology;

[0038] Step 2: Calculate the scouring force of the slope surface water flow based on the regional rainfall intensity, slope area, slope angle and slope length data. Combined with the cementing force generated by microbial mineralization and the amount of calcium carbonate precipitation, determine the number of microbial reinforcement times, that is, the number of times the cementing liquid is sprayed.

[0039] Step 3. According to the number of reinforcements determined in step 2, a binder obtained by mixing Bacillus licheniformis solution and calcium propionate solution is sprayed on the slope surface and the lattice to bind the soil particles on the slope surface, so that a layer of calcium carbonate protective film is formed on the soil surface, which can effectively improve the soil's anti-scouring ability, reduce the flow of soil particles, and protect plant growth.

[0040] Specifically, the concentration of the Bacillus licheniformis solution is 0.1 mol / L to 1.0 mol / L, the concentration of the calcium propionate solution is 0.5 mol / L to 1.5 mol / L, and the volume ratio of the Bacillus licheniformis solution to the calcium propionate solution in the cementing liquid is 1:5 to 1:1.

[0041] Using CO3 produced by aerobic respiration of Bacillus licheniformis 2- It combines with calcium ions in calcium propionate to form calcium carbonate. The precipitation formation principle is similar to that of urease-producing microorganisms, but the induced precipitation process is more environmentally friendly than urease-producing bacteria. The secondary products are only carbon dioxide and water, to be specific.

[0042] Ca(C3H5O2)2+8O2→CaCO3↓+5CO2↑+5H2O

[0043] In the process of inducing precipitation by Bacillus licheniformis, there are only carbon dioxide and water, which has almost no impact on the environment. It can generate calcium carbonate precipitation to protect plant roots and avoid environmental damage. In addition, traditional biological measures only use the method of planting vegetation. When encountering heavy rainfall, the slope surface will be washed and eroded by rainwater, and the shallowly buried plant roots will quickly expose the surface, which may eventually cause the death of vegetation. The calcium carbonate precipitation induced by Bacillus licheniformis is stable in nature, has good mechanical properties, and strong durability. It can quickly cement soil particles and effectively avoid the occurrence of such problems. At the same time, Bacillus licheniformis can also improve soil water storage and energy storage, improve crop disease resistance, inhibit the reproduction and invasion of soil pathogens, reduce diseases, prevent pest outbreaks, reduce various fungal diseases, and promote crop growth and maturity. Finally, the calcium carbonate precipitation generated by Bacillus licheniformis is also beneficial to the slope protection project of drainage ditches. Compared with traditional concrete slope protection, it has the advantages of economy, environmental protection, high efficiency and controllability. The Bacillus licheniformis on the slope surface will flow toward crops along with the water flow, which is very beneficial to the crops at the corners of the slope.

[0044] The method of combining Bacillus licheniformis with biological measures for control can produce various beneficial effects in promoting plant growth and protecting shallow vegetation, reinforcing slopes, and solidifying drainage ditch slopes, and the impact on the environment is minimal. It is more advantageous than urease-producing bacteria. Therefore, compared with existing control measures, the microbial technology proposed in the present invention has advantages in many aspects such as ecological protection, efficiency, and economy, and is expected to produce very significant effects and has broad application prospects.

[0045] Embodiment 2

[0046] As another embodiment, this embodiment 2 proposes a more specific method for improving soil and water loss with microorganisms based on the embodiment 1:

[0047] In step 2, relevant data are queried, including rainfall intensity, slope area, slope angle and slope length in the area, and the scouring force of the slope surface water flow is calculated to determine the number of microbial reinforcements to save materials and costs. The calculation method of the number of microbial reinforcements n is:

[0048] a(1+m) n =W(ρμ 1x μ 1y -1 -ρμ 2x μ 2y -1 )L -1

[0049] Where: a is the original soil cohesion, which can be obtained by consulting relevant literature, n is the number of times the cementing fluid is sprayed, b represents the percentage of cohesion between soil particles increased after each reinforcement, which needs to be measured by shear test; W represents the scour coefficient. When the slope water flow depth is 1.0 to 3.5 cm, W = (2.07 to 16.71) × 10 -5 ρ is the density of slope soil particles, which can be obtained through actual measurement, μ 1x and μ 1y are the lateral and longitudinal shear stresses of the water flow at the toe of the slope, μ 2x and μ 2y They are the transverse and longitudinal shear stresses of the water flow at the top of the slope, respectively, which can be calculated by the water flow velocity, etc. L is the length of the slope, that is, the distance from the top of the slope to the slope corner.

[0050] When preparing the cementing liquid, first prepare the microbial liquid. The microbial liquid is a bacterial culture liquid, and the bacteria are Bacillus licheniformis; first separate from the soil, and use the property that Bacillus licheniformis can grow on propionate. In this embodiment, the formula of the bacterial culture liquid is: add 10g of tryptone, 5g of yeast extract, 10g of sodium chloride and 15g of agar to 1000g of distilled water. The concentrations are 0.01%, 0.005% of yeast extract, 0.1% of sodium chloride and 0.014% of agar respectively.

[0051] In this embodiment, in step three, through experimental comparison, too high or too low concentration will affect the aerobic respiration of Bacillus licheniformis, and ultimately affect the calcium carbonate content. Preferably, the concentration of Bacillus licheniformis bacterial solution is 0.5 mol / L, the concentration of calcium propionate solution is 1.0 mol / L, and the volume ratio of Bacillus licheniformis bacterial solution and calcium propionate solution in the binder is 1:4, which provides carbonate ions and calcium ions for the MICP process and provides sufficient nutrients for the growth and reproduction of bacteria.

[0052] The single spraying amount Q of the cementing fluid is:

[0053] Q=(a+b)[(A×d) / n] / c

[0054] A is the slope area; d is the mass of Bacillus licheniformis sprayed per unit area each time; n is the molecular weight of Bacillus licheniformis, c is the concentration of Bacillus licheniformis solution, a and b represent the volume ratio of Bacillus licheniformis solution to calcium ion solution, respectively, where a=1.

[0055] After each spraying, let it stand for 7 to 10 days and maintain the ambient temperature at 20 to 35°C before the next injection to allow the Bacillus licheniformis to fully react and the cementing liquid to seep downward.

[0056] In this embodiment, after the binder liquid is sprayed on the soil 5 to 8 times, the pH value of the soil changes the most, rising from 7.0 to 7.5, the pH value of the soil changes little, the ammonium ion concentration is 0, and the original nitrogen balance will not be destroyed. After long-term experiments, it was found that after spraying with Bacillus licheniformis solution and calcium ion solution, the growth cycle of vegetation was significantly shortened and the growth was more vigorous.

[0057] Bacillus licheniformis can also increase the number of beneficial bacteria in the soil, improve the root environment, promote plant growth and inhibit the reproduction of harmful microorganisms. It can improve the soil aggregate structure, improve the soil, adjust the soil pH, increase the soil water storage and heat preservation, improve the disease resistance of crops, promote plant growth and maturity, and improve the effect of soil and water conservation after vegetation growth. The generated calcium carbonate can also cement soil particles and reduce soil erosion. Bacillus licheniformis plays a dual role.

[0058] The growth of plants not only increases the erosion resistance and skidding resistance of the slope, but also effectively reduces the risk of soil erosion on the slope. The roots of plants can firmly grasp the soil particles, forming a natural fixing layer, providing additional support for the slope and reducing erosion and denudation of the slope. The roots of plants take root and expand in the soil, forming a complex root network. This root network helps to enhance the structure and cohesion of the soil, reduce soil erosion and soil erosion, and improve the skidding resistance of the slope.

[0059] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0060] Embodiment 3

[0061] As another embodiment, this embodiment 3 proposes a more specific method for improving soil and water loss with microorganisms based on embodiments 1 and 2:

[0062] In step one, hydraulic spraying technology is used. Hydraulic spraying is highly mechanized and can quickly plant grass over a large area. Different plants can be selected for mixed seeding based on specific natural conditions or design requirements to achieve complementary advantages in terms of growth period and stress resistance. The advantages of different plants are complemented, which increases the feasibility of practical application of the project.

[0063] When the slope is a soil slope 1, such as Figure 1 As shown, in step 1, plants 3 are directly planted on the slope surface, and the plants 3 cover the entire slope surface. A drainage ditch 7 is set in the soil slope 1 to accelerate drainage and prevent excessive rainfall intensity, which causes the scouring force to be much greater than the microbial bonding force, aggravating the erosion of the slope by water flow, destroying the slope stability, and causing serious soil and water loss. Combined with the mineralization of microorganisms, the soil particles around the plants are bonded to protect the plant roots, prevent bare leakage, reduce the cost of later maintenance, and reduce soil and water loss.

[0064] When spraying the binder, the drainage ditch 7 is also sprayed with Bacillus licheniformis solution and calcium propionate solution in sequence, which can enhance the stability of the drainage ditch 7 of the soil slope 1, reduce the subsequent maintenance costs, replace the traditional drainage ditch slope protection method, and protect the ecological environment.

[0065] When the slope is a rock slope 4, a lattice structure is first set on the surface of the rock slope 4, and then the lattice structure is filled with soil and the plants 3 are planted. Figure 2 shown.

[0066] The lattice structure on the surface of the rock slope 4 is rectangular, the lattice beams 5 have a horizontal spacing of 2.5 to 3.0 m, and the vertical spacing of the lattice beams 5 is 3.5 to 4.5 m; the lattice structure is anchored on the surface of the rock slope 4 by anchor rods or anchor cables 6. Specifically, the selection of anchor rods or anchor cables is determined according to the stability of the slope. When the slope stability is good, but collapse and sliding occur due to the excavation of the front surface, anchor rod reinforcement is selected; when the slope stability is poor or the downward force is large, anchor cable reinforcement is selected.

[0067] The anchor rod body material is made of glass fiber reinforcement, which can effectively prevent solution corrosion during the MICP process. It has the advantages of high strength, light rod body, easy cutting, and reasonable price, and is very suitable for a wide range of engineering applications. The anchor rod drilling hole diameter is 10-13cm, and the anchor rod length is 20m. According to the actual slope analysis, the anchor grouting material is selected to determine the effective anchor length and the angle between the anchor rod and the horizontal plane, including the bonding strength of the anchor rod anchor section.

[0068] Different infiltration methods are selected according to different soil conditions. When the soil permeability coefficient is too small and difficult to infiltrate, the cementing liquid obtained by mixing Bacillus licheniformis solution and calcium propionate solution is infiltrated into the slope by grouting.

[0069] Filling soil in the lattice to increase the soil's anti-erosion capability and reduce soil loss. In this embodiment, the cross-sectional dimensions of the lattice beam 5 are 300 mm×300 mm, and the concrete strength grade is C25.

[0070] It should be noted that the parts in this embodiment that are the same or similar to those in Embodiments 1 and 2 can be referenced to each other and will not be described in detail in this application.

[0071] Comparative Example 1

[0072] As a comparative example, Bacillus subtilis was used to control soil erosion on loess slopes. After 5 to 8 times of spraying of the binder, the pH value of the soil increased from 7.0 to 9.6. At the same time, NH4 + The concentration also increased from 0 to 90mmol / L. It can be seen that the secondary products of Bacillus pasteurianus, which is commonly used in MICP technology, will change the original pH of the soil.

[0073] Compared with the Bacillus licheniformis binder used in Example 2, the pH value caused by the treatment of soil erosion on loess slopes with Bacillus parvum is greatly changed, and ammonium ions are produced, which changes the original properties of the soil and affects the growth of plants.

[0074] Comparative Example 2

[0075] As another comparative example, Bacillus subtilis was used to control soil erosion on clay slopes. After 6 to 8 times of spraying the binder, the pH value of the soil increased from 7.0 to 9.2, and NH4 + The concentration also rose to 82mmol / L, which is the same as the comparative example 1, and also changed the original properties of the soil and affected the growth of plants. In comparison, the Bacillus licheniformis cementing liquid used in this method has a better auxiliary effect on covering planting.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A method for improving soil and water loss by microorganisms, characterized in that: The following steps are involved: Step 1: The plant seeds are germinated and sprayed on the slope using hydraulic spraying technology; Step 2: Setting a lattice structure on the surface of the rock slope, filling the lattice structure with soil and then planting plants; Step 3: Calculate the scouring force of the slope surface water flow based on the regional rainfall intensity, slope area, slope angle and slope length data, and determine the number of microbial reinforcements based on the cementation force and calcium carbonate precipitation generated by microbial mineralization; Step 4: According to the reinforcement times determined in step 3, a cementing liquid obtained by mixing Bacillus licheniformis solution and calcium propionate solution is sprayed on the slope surface and the lattice.

2. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 4, the concentration of the Bacillus licheniformis solution is 0.1 mol / L to 1.0 mol / L, the concentration of the calcium propionate solution is 0.5 mol / L to 1.5 mol / L, and the volume ratio of the Bacillus licheniformis solution to the calcium propionate solution in the binder is 1:5 to 1:

1.

3. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 3, the calculation method of the number of microbial reinforcement n is: a(1+b) n =W(ρμ 1x m 1y -1 -rm 2x m 2y -1 )L -1 Where: a is the original soil cohesion, n is the number of times the cementing fluid is sprayed, b represents the percentage of the cohesion between soil particles increased after each reinforcement; W represents the scour coefficient, ρ is the density of slope soil particles, μ 1x and μ 1y are the lateral and longitudinal shear stresses of the water flow at the toe of the slope, μ 2x and μ 2y are the lateral and longitudinal shear stresses of water flow at the top of the slope, respectively, and L is the length of the slope.

4. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 4, the single spraying amount Q of the cementing liquid is: Q=(a+b)[(A×d) / n] / c A is the slope area; d is the mass of Bacillus licheniformis sprayed per unit area each time; n is the molecular weight of Bacillus licheniformis, c is the concentration of Bacillus licheniformis solution, a and b represent the volume ratio of Bacillus licheniformis solution to calcium ion solution, respectively, where a=1.

5. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 4, the concentration of the Bacillus licheniformis solution is 0.5 mol / L, the concentration of the calcium propionate solution is 1.0 mol / L, and the volume ratio of the Bacillus licheniformis solution to the calcium propionate solution in the cementing liquid is 1:

4.

6. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 4, a cementing solution obtained by mixing Bacillus licheniformis solution and calcium propionate solution is infiltrated into the slope by a grouting method.

7. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: In step 2, the lattice is rectangular, the lattice beams have a lateral spacing of 2.5 to 3.0 m, and the lattice beams have a vertical spacing of 3.5 to 4.5 m; the lattice is anchored on the surface of the rock slope by anchor rods or anchor cables.

8. The method for improving soil and water loss by microorganisms according to claim 1, characterized in that: When the slope is an earth slope, in step 2, plants are directly planted on the surface of the slope, the plants cover the entire surface of the slope, and drainage ditches are set in the earth slope. In step 4, the drainage ditches are also sprayed with cementing liquid.

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