Microbial soil conditioner for in-situ rejuvenation of border trees

Abstract

The invention provides a microbial soil conditioner for in-situ rejuvenation of border trees. The soil conditioner comprises a chemical loosening conditioner (composed of modified sodium carboxymethyl cellulose and citric acid-malic acid composite organic acid), a biological stimulant (composed of bacillus subtilis exopolysaccharide and a seaweed extract) and a physical loosening auxiliary agent (composed of expanded perlite and crushed garden waste). Functional strains (bacillus subtilis and bacillus mucilaginosus) and a protective agent (food-grade sucrose fatty acid ester). According to the invention, a triple synergistic system of chemical loosening-physical supporting, biological stimulation-microbial colonization and nutrient activation-stress tolerance adaptation is constructed, the chemical conditioner rapidly disperses clay particles, the physical auxiliary agent constructs a stable pore skeleton, the biological components promote aggregate formation and microbial colonization, the soil porosity can be increased from less than 15% to 20% or more within 7 days, and the soil quality is improved. The conductivity is reduced to 1.8 mS / cm or below within 30 days, and the pH is adjusted to 6.5-7.5.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soil improvement, and particularly relates to a microbial soil improver for in-situ rejuvenation of street trees. BACKGROUND

[0002] As an important part of urban greening, the growth of urban street trees directly affects the urban ecological environment and landscape effect. However, the soil of urban street trees generally faces multiple stress problems: first, the soil is severely compacted, and the soil porosity is generally less than 15% due to the limitation of pedestrian trampling, vehicle crushing and paving, which is far below the 20% threshold suitable for root growth, resulting in oxygen deficiency and respiratory obstruction of roots; second, the imbalance of physicochemical properties, the soil electrical conductivity is often more than 2.0 mS / cm due to the residual of snow-melting agent, and the pH value is abnormal (acidic < 6.0 or alkaline > 8.0) caused by acid rain or alkaline sewage irrigation, which significantly inhibits microbial activity; third, the construction conditions are limited, and deep ploughing machinery cannot be used in the core area of the city, narrow pedestrian areas and densely distributed underground pipelines, so that the traditional soil improvement and deep ploughing are difficult to implement.

[0003] In the existing soil improvement technology, microbial agents are widely concerned due to their environmental friendliness and long-lasting improvement effect, but there are obvious limitations in directly applying ordinary microbial agents: on the one hand, ordinary strains have not been domesticated for low-oxygen and salt-tolerant, and their activity decreases by more than 60% within 7 days in compacted and high-salt soil, so they cannot form effective microbial populations; on the other hand, there is a lack of targeted carriers or conditioning systems, so it is difficult to solve the core problem of insufficient soil porosity after the application of microbial agents, and separate physical loosening measures are needed, which increases the construction complexity and cost.

[0004] Some improvement technologies use expanded vermiculite, perlite and other physical carriers to improve porosity, but there are problems such as poor compatibility between carriers and microbial agents, high cost and inconvenience in applying in paving areas; another technology uses chemical conditioning agents to disperse clay particles, but single chemical agents can easily cause secondary damage to soil structure, and cannot provide a stable colonization environment for microorganisms. Therefore, it is a key requirement to develop a soil improver that can simultaneously improve porosity and microbial colonization without deep ploughing, which solves the problem of urban street tree soil. SUMMARY

[0005] The technical problem to be solved is that, in view of the above problems, the purpose of the present application is to provide a microbial soil improver for in-situ rejuvenation of street trees, which constructs a triple synergistic system of chemical loosening-physical support, biological stimulation-microbial colonization, nutrient activation-adaptation to stress, the chemical conditioning agent quickly disperses clay particles, the physical auxiliary agent constructs a stable pore skeleton, and the biological component promotes the formation of granules and microbial colonization, which can increase the soil porosity from < 15% to more than 20% within 7 days, reduce the electrical conductivity to less than 1.8 mS / cm within 30 days, and adjust the pH to 6.5-7.5.

[0006] Technical solution: A microbial soil conditioner for in-situ rejuvenation of roadside trees, comprising, by weight, a chemical loosening conditioner, a biostimulant, a physical loosening aid, functional strains, and a protectant; The chemical loosening conditioner is composed of 13-17 parts modified sodium carboxymethyl cellulose and 6-10 parts citric acid-malic acid complex organic acid; The biostimulant is composed of 8-12 parts of Bacillus subtilis extracellular polysaccharide and 5-9 parts of seaweed extract; The physical loosening agent is composed of 18-22 parts expanded perlite and 13-17 parts pulverized garden waste; The functional strain consists of 10-14 parts of Bacillus subtilis and 4-8 parts of Bacillus mucilage; The protective agent is 3-7 parts of food-grade sucrose fatty acid ester.

[0007] Furthermore, the modified sodium carboxymethyl cellulose has a viscosity ≤500 mPa·s, a dissolution time in water at 25°C ≤30 min, and a dispersion particle rate ≥50%; the mass ratio of citric acid to malic acid in the citric acid-malic acid composite organic acid is 2-3:1 and the concentration is 80%.

[0008] Furthermore, the preparation method of the modified sodium carboxymethyl cellulose is as follows: S1. Raw material pretreatment: Take 100 parts by weight of refined cellulose, add 500-600 parts by weight of a mixed solvent of isopropanol and water in a mass ratio of 3:1, and stir and disperse at 100-120 r / min for 15-20 min to form a uniform and stable suspension. S2. Alkalization reaction: Place the suspension in a constant temperature water bath and cool it to 20-25℃. Slowly add 30-40 parts by weight of 45% sodium hydroxide solution. After the addition is complete, continue stirring for 60-90 minutes to fully alkalize the cellulose and generate alkali cellulose. During this process, the temperature fluctuation should be controlled to not exceed ±2℃ to ensure uniform alkalization. S3. Etherification reaction: Heat the system to 55-60℃, add 40-50 parts by weight of 80% chloroacetic acid at a rate of 1-2 mL / min, and control the addition time to 30-45 min. Then keep the reaction at the temperature for 120-150 min, and keep stirring at 120-150 r / min during the process. S4. Neutralization and purification: After the reaction is complete, slowly add glacial acetic acid to the system to adjust the pH to 6.5-7.0 and terminate the reaction; place the reaction solution in a centrifuge and centrifuge at 3000 r / min for 10 min, collect the solid product, and wash it 2-3 times with a mixed solvent of isopropanol-water by mass ratio. S5. Drying and crushing: the washed solid product is dried at 60-70℃, -0.08MPa to a water content of ≤8%, and then removed and crushed by a super micro grinder to a particle size of 0.1-0.5mm to obtain modified sodium carboxymethyl cellulose.

[0009] Further, the molecular weight of the exopolysaccharide of Bacillus subtilis is 10000-50000Da; the content of alginic acid in the seaweed extract is ≥20%.

[0010] Further, the bulk density of the expanded perlite is ≤80kg / m 3 , and the porosity is ≥75%; the crushed garden waste is a harmless treatment product of green pruning branches and fallen leaves, and the cellulose content is ≥70%.

[0011] Further, the effective viable count of the Bacillus subtilis is ≥2×10 10 CFU / g, and the low oxygen tolerance rate under 5% oxygen concentration is ≥65%; the effective viable count of the Bacillus megaterium is ≥1×10 9 CFU / g, and the salt tolerance rate under 4.0mS / cm conductivity is ≥80%.

[0012] Further, the HLB value of the food-grade sucrose fatty acid ester is 8-10.

[0013] The preparation method of the microbial soil conditioner for in-situ rejuvenation of street trees comprises the following steps: (1) Pretreatment: the expanded perlite is autoclaved at 121℃ for 20-30min, and the garden waste is crushed to 2-5mm and dried at 60℃ to a water content of ≤10%; (2) Mixing: the chemical loosening conditioner and the biological stimulant, the physical loosening auxiliary agent, the functional strain and the protective agent are sequentially mixed in proportion, the rotation speeds of the double-helix mixers are 150-200r / min, 100-150r / min and 80-100r / min respectively, and the mixing times are 5-8min, 8-10min and 3-5min respectively, and then the microbial soil conditioner for in-situ rejuvenation of street trees is obtained.

[0014] The application method of the microbial soil conditioner for in-situ rejuvenation of street trees comprises the following steps: - Non-paved area: the application amount of the microbial soil conditioner for in-situ rejuvenation of street trees is 450-550g / tree for young trees, 900-1100g / tree for middle-aged trees, and 1400-1600g / tree for old trees, the microbial soil conditioner for in-situ rejuvenation of street trees is scattered and then lightly raked for 3-5cm, 1-2cm of fine soil is covered, and 5-10L of water is poured per tree; - Paved area: the microbial soil conditioner for in-situ rejuvenation of street trees is diluted at a ratio of 1:8-12, 0.12%-0.18% Tween-80 is added, 2-3L / m 2 of high-pressure spray is applied, and 1-2cm of decomposed pine needles is covered; - Late maintenance: water once every 5-7 days within 1 month after application, and add half the amount of the amendment 1.2-1.8 months later.

[0015] Further, when the soil conductivity is > 3.5 mS / cm, the application amount is increased by 15%-25%; the soil moisture content is maintained at 20%-23% after application. Beneficial effects

[0016] 1. The present application constructs a triple synergistic system of chemical loosening-physical support, biological stimulation-microbial colonization, nutrient activation-stress resistance adaptation. The chemical conditioner quickly disperses clay particles, the physical auxiliary agent constructs a stable pore skeleton, and the biological component promotes pellet formation and microbial colonization. Within 7 days, the soil porosity can be increased from < 15% to more than 20%, the conductivity can be reduced to below 1.8 mS / cm within 30 days, and the pH can be adjusted to 6.5-7.5.

[0017] 2. In the present application, the modified sodium carboxymethyl cellulose in the chemical loosening conditioner exchanges with the cations on the surface of soil clay particles through the carboxyl groups on the molecular chain, breaks the hydrogen bond connection between clay particles, and quickly disperses the micro-aggregates of hardened soil, creating a path for the subsequent penetration of the improvement components. The expanded perlite in the physical loosening auxiliary agent forms a rigid support skeleton in the soil due to its porous structure, avoiding re-compaction of the improved soil due to external force treading. At the same time, the fiber network of garden waste can form a complement with the perlite pores, constructing a reasonable pore grading of large pore aeration-small pore water retention. The biological stimulant and functional strain quickly colonize the microenvironment created by chemical loosening, and the exopolysaccharide of Bacillus subtilis can be used as a cementing material to cement the dispersed clay and silt particles into water-stable pellet structures. The phosphorus solubilization of Bacillus mucilaginosus activates the nutrients in the soil, providing nutrient support for the stability of the pellet structure. This synergistic effect promotes the improvement effect, avoiding the soil structure degradation caused by single chemical amendment or the inability to maintain long-term effect caused by single physical amendment.

[0018] 3. The soil improver in the application aims at the pain point of urban core area, densely paved area and surrounding underground pipeline that cannot be deep ploughed, and develops around the core demand of "surface application and deep action" from component design to application method. The low viscosity characteristics of modified sodium carboxymethyl cellulose make it have good diffusivity in water, and can penetrate to the main root distribution layer of 15-20 cm through soil capillary action without mechanical turning to realize the loosening of deep soil. The particle size of expanded perlite and garden waste is controlled in 2-5 mm, which not only ensures the uniformity when it is applied on the surface, but also can penetrate into the soil below the surface with water after watering, and combine with dispersed clay particles to form a support structure. The functional strains can tolerate short-term drought and temperature fluctuations in the surface soil under the protection of sucrose fatty acid ester, and gradually colonize to the deep layer. This "surface application and layered action" mode can complete the construction only by manual application or small spray equipment, greatly reducing the interference degree to the surrounding pavement, underground pipeline and pedestrian traffic, and solving the problem that the traditional deep ploughing improvement technology cannot be applied in special urban areas.

[0019] 4. The application selects Bacillus subtilis and Bacillus mucilaginosus maturely applied in the field of agriculture, and the protective agent sucrose fatty acid ester forms a molecular film to wrap the strain cells, reducing the damage of high salt, acid-base imbalance and other adversity in the soil to the strain cell membrane. Meanwhile, the HLB value of 8-10 can reduce the surface tension of the soil, promote the contact between the strain cells and the soil particles, and improve the low oxygen tolerance rate of the strain in the compacted soil. In addition, the resource utilization of garden waste not only reduces the cost of physical loosening auxiliary agent, but also releases organic matter during the degradation process, which can provide a sustained carbon source for functional strains, forming a virtuous cycle of strain colonization-organic matter decomposition-nutrient release-strain proliferation, and ensuring the long-term stability of the improvement effect.

[0020] 5. The application realizes the directional regulation of soil pH, conductivity and nutrient status through precise proportioning of components. The citric acid-malic acid complex organic acid adjusts the soil pH to the suitable range of 6.5-7.5 for root system through buffering effect, and its calcium chelating ability can reduce the solidification degree of calcium ions in saline-alkali soil, while providing absorbable organic carbon source for root system; the dispersion effect of modified sodium carboxymethyl cellulose can reduce the content of soil clay particles, and cooperate with the pore support of perlite to improve the soil aeration porosity to more than 15%, meeting the oxygen demand of root respiration; the phosphorus-solubilizing effect of Bacillus mucilaginosus can convert the insoluble phosphorus in the soil into available phosphorus, and the protease produced by Bacillus subtilis can promote the decomposition of soil organic matter, providing essential nutrients such as nitrogen and phosphorus for root growth. This precise regulation of root microenvironment can activate the physiological activity of root system, promote the secretion of auxin, and enhance the resistance of trees to drought, saline-alkali and other adversity, fundamentally improving the growth conditions of street trees.

[0021] 6. All components of the present application are environmentally friendly materials, without secondary pollution. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Bend line graph of soil index (porosity, pH, conductivity) change over time after the microbial soil amendment of Example 9 is applied to the soil; Figure 2 Bend line graph of microbial colonization change over time after the microbial soil amendment of Example 9 and Comparative Example 2 is applied. DETAILED DESCRIPTION

[0023] The present application proposes a microbial soil amendment for in-situ rejuvenation of street trees, in order to make the purpose, technical solution and effect of the present application more clear and explicit, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0024] The mass ratio of citric acid to malic acid in the citric acid-malic acid composite organic acid is 2-3:1, and the concentration is 80%; the molecular weight of the exopolysaccharide of Bacillus subtilis is 10000-50000 Da; the content of alginic acid in the seaweed extract is 21.2%; the bulk density of the expanded perlite is 78.6 kg / m 3 , the porosity is 78.7%; the pulverized garden waste is the product of harmless treatment of green pruning branches and fallen leaves, and the average content of cellulose is 71.6%; the effective viable count of Bacillus subtilis (number: CICC10732) is 2.2×10 10 CFU / g, and the low-oxygen tolerance rate under 5% oxygen concentration is 67.5%; the effective viable count of Bacillus megaterium (number: SHMCCD12018) is 1.8×10 9 CFU / g, and the salt tolerance rate under 4.0 mS / cm conductivity is 81.3%; the HLB value of the food-grade sucrose fatty acid ester is 8-10.

[0025] Example 1 The preparation method of the modified sodium carboxymethyl cellulose is as follows: S1. Raw material pretreatment: take 100 kg of refined cellulose, add 500 kg of mixed solvent of isopropyl alcohol and water with a mass ratio of 3:1, stir and disperse at a speed of 100 r / min for 15 min to form a uniform and stable suspension; S2. Alkalization reaction: place the suspension in a constant temperature water bath, cool to 20℃, slowly add 30 kg of sodium hydroxide solution with a concentration of 45%, continue to stir for 60 min after the addition is completed, control the temperature fluctuation within ±2℃, and make the cellulose fully alkalized to form alkali cellulose; S3. Etherification reaction: the system is warmed to 55°C, 40 kg of chloroacetic acid with a concentration of 80% is added dropwise at a rate of 1 mL / min, the dropwise time is controlled within 30 min, and then the reaction is kept for 120 min with stirring at 120 r / min; S4. Neutralization and purification: after the reaction is completed, glacial acetic acid is slowly added to the system to adjust the pH to 6.5 to terminate the reaction; the reaction solution is placed in a centrifuge and centrifuged at a speed of 3000 r / min for 10 min, and the solid product is collected and washed twice with a mixed solvent of isopropyl alcohol and water with a mass ratio of 3:1; S5. Drying and crushing: the washed solid product is dried at 60°C and -0.08 MPa until the water content is 7.8%, and then taken out and crushed to a particle size of 0.1-0.5 mm with a super micro crusher.

[0026] Example 2 The preparation method of modified sodium carboxymethyl cellulose is as follows: S1. Raw material pretreatment: 100 kg of refined cellulose is added into 550 kg of a mixed solvent of isopropyl alcohol and water with a mass ratio of 3:1, and stirred and dispersed at a speed of 110 r / min for 18 min to form a uniform and stable suspension; S2. Alkali reaction: the suspension is placed in a constant temperature water bath, and 35 kg of sodium hydroxide solution with a concentration of 45% is slowly added dropwise, and after the dropwise addition is completed, the stirring reaction is continued for 75 min, and the temperature fluctuation is controlled within ±2°C, so that the cellulose is fully alkali-treated to form alkali cellulose; S3. Etherification reaction: the system is warmed to 58°C, 45 kg of chloroacetic acid with a concentration of 80% is added dropwise at a rate of 1.5 mL / min, the dropwise time is controlled within 38 min, and then the reaction is kept for 135 min with stirring at 135 r / min; S4. Neutralization and purification: after the reaction is completed, glacial acetic acid is slowly added to the system to adjust the pH to 6.8 to terminate the reaction; the reaction solution is placed in a centrifuge and centrifuged at a speed of 3000 r / min for 10 min, and the solid product is collected and washed three times with a mixed solvent of isopropyl alcohol and water with a mass ratio of 3:1; S5. Drying and crushing: the washed solid product is dried at 65°C and -0.08 MPa until the water content is 7.8%, and then taken out and crushed to a particle size of 0.1-0.5 mm with a super micro crusher.

[0027] Example 3 The preparation method of modified sodium carboxymethyl cellulose is as follows: S1. Raw material pretreatment: 100 kg of refined cellulose is added into 550 kg of a mixed solvent of isopropyl alcohol and water with a mass ratio of 3:1, and stirred and dispersed at a speed of 110 r / min for 18 min to form a uniform and stable suspension; S2. Alkali reaction: Place the suspension in a constant temperature water bath and cool it to 25°C. Slowly add 40 kg of 45% sodium hydroxide solution, and continue stirring for 90 min after the addition is complete. Control the temperature fluctuation within ±2°C to fully alkalinize the cellulose to produce alkali cellulose; S3. Etherification reaction: Warm the system to 60°C, and add 50 kg of 80% chloroacetic acid at a rate of 2 mL / min. The addition time is controlled within 45 min, and then keep the reaction for 150 min with stirring at 150 r / min; S4. Neutralization and purification: After the reaction is completed, slowly add glacial acetic acid to the system to adjust the pH to 7.0 to terminate the reaction. Centrifuge the reaction liquid at 3000 r / min for 10 min, and collect the solid product. Wash the solid product with a mixture of isopropyl alcohol and water (mass ratio 3:1) for 3 times. S5. Drying and crushing: Dry the washed solid product at 70°C and -0.08 MPa until the water content is 7.7%. After taking out, crush it to a particle size of 0.1-0.5 mm with a super micro crusher.

[0028] Performance test: 1. Viscosity determination: Refer to GB / T 15357-2014 "Surface-active agents and detergents - Rotational viscometer method for the determination of the viscosity and flow properties of liquid products". Weigh 2.000 g of modified carboxymethyl cellulose sodium sample, add 98 mL of deionized water, and stir at 200 r / min for 10 min. Then place it in a constant temperature water bath at 25°C for 30 min to ensure complete dissolution of the sample and stable temperature. Slowly immerse the viscometer 0# rotor into the sample solution to the specified scale, start the instrument, and record the value after the reading is stable for 30 s. Repeat the test 3 times, and take the average value as the final viscosity result. 2. Determination of dissolution time in 25°C water: Add 100 mL of 25°C deionized water to a conical flask, place it on a magnetic stirrer, and put in a stirrer. Weigh 1.00 g of modified carboxymethyl cellulose sodium sample and add it to the conical flask at one time. Start the stopwatch at the same time. Continue stirring until there are no visible particles or flocs in the solution. Immediately stop the stopwatch and record the time used. Repeat the test 3 times, and take the average value as the dissolution time result. 3. Determination of dispersed clay content: sample preparation: collect typical row tree hardened soil (clay content is 35-37%), dry in the air, and sieve through a 2 mm sieve to remove impurities; weigh 10.00 g of sieved soil, add 50 mL of deionized water to prepare a soil suspension; weigh 0.50 g of modified carboxymethyl cellulose sodium sample, add it to the above soil suspension, and stir at a speed of 300 r / min for 20 min; transfer the prepared soil suspension into a centrifugal tube, centrifuge at a speed of 3000 r / min for 15 min; carefully pour out the supernatant, and dry the sediment in the centrifugal tube to constant weight, weigh the mass of the sediment (recorded as m1); at the same time, prepare a blank control (soil suspension without modified carboxymethyl cellulose sodium), weigh the mass of the sediment of the blank group (recorded as m0); the calculation formula of the dispersed clay content is: dispersed clay content (%) = (m0-m1) / m0x100%, repeat the test for 3 times, and take the average value as the final result; The results are shown in Table 1 as follows: Table 1 Viscosity (mPa-s) Dissolution time in water at 25°C (min) Dispersion of clay particles (%) Example 1 322 22 52 Example 2 410 26 58 Example 3 479 29 60 The modified carboxymethyl cellulose sodium prepared in the above three examples all meet the use requirements of the improver of the application, wherein the comprehensive performance of example 2 is the best, the dissolution speed and the clay dispersion effect are both considered, which is the preferred preparation scheme, so the modified carboxymethyl cellulose sodium prepared in example 2 is used subsequently.

[0029] Example 4 The preparation method of the soil improver for conventional improvement of middle-aged trees (non-paving area) is as follows: Step 1. Pretreatment: take 20 kg of expanded perlite, sterilize at 121℃ for 25 min, and cool to room temperature; take 15 kg of garden waste, crush to 2-5 mm, and dry at 60℃ to a water content of 9.6%, for standby; Step 2. Mixing: weigh the chemical loosening conditioner (15 kg of modified carboxymethyl cellulose sodium prepared in example 2, 8 kg of citric acid-malic acid composite organic acid) and the biological stimulant (10 kg of exopolysaccharide of bacillus subtilis, 7 kg of seaweed extract) according to the proportion, put them into a double-screw mixer, mix at a speed of 180 r / min for 6 min; add the pretreated physical loosening auxiliary agent (20 kg of expanded perlite, 15 kg of crushed garden waste), reduce the speed to 120 r / min, and mix for 9 min; finally, add 12 kg of bacillus subtilis and 6 kg of bacillus mucilaginosus and 5 kg of food-grade sucrose fatty acid ester, mix at a speed of 90 r / min for 4 min, and the soil improver is obtained.

[0030] Example 5 The preparation method of the soil improver for paving area of young trees (low dosage and high dispersion) is as follows: Step 1. Pretreatment: Take 18 kg of expanded perlite, high-pressure sterilization at 121°C for 25 min; take 17 kg of garden waste, crush to 2-5 mm, dry at 60°C to a moisture content of 9.6%, ready for use; Step 2. Mixing: Take chemical loose conditioning agent (modified carboxymethyl cellulose sodium prepared in Example 2, 13 kg, citric acid-malic acid complex organic acid, 10 kg) and biological stimulant (Bacillus subtilis exopolysaccharide, 8 kg, seaweed extract, 9 kg), double helix mixer speed 150 r / min, mix for 8 min; add physical loose auxiliary agent, speed down to 100 r / min, mix for 10 min; add functional strains (Bacillus subtilis, 10 kg, Bacillus mucilaginosus, 8 kg) and sucrose fatty acid ester, 7 kg, speed 80 r / min, mix for 5 min, ready.

[0031] Example 6 The preparation method of the soil conditioner for saline-alkali old trees (high salt-tolerant formula) is as follows: Step 1. Pretreatment: Take 22 kg of expanded perlite, high-pressure sterilization at 121°C for 25 min; take 13 kg of garden waste, crush to 2-5 mm, dry at 60°C to a moisture content of 9.6%, ready for use; Step 2. Mixing: Take chemical loose conditioning agent (modified carboxymethyl cellulose sodium prepared in Example B, 17 kg, citric acid-malic acid complex organic acid, 10 kg) and biological stimulant (Bacillus subtilis exopolysaccharide, 12 kg, seaweed extract, 9 kg), double helix mixer speed 200 r / min, mix for 5 min; add physical loose auxiliary agent, speed down to 150 r / min, mix for 8 min; add functional strains (Bacillus subtilis, 14 kg, Bacillus mucilaginosus, 8 kg) and sucrose fatty acid ester, 7 kg, speed 100 r / min, mix for 3 min, ready.

[0032] Example 7 The preparation method of the soil conditioner for acidic and compacted soil (high loose) is as follows: Step 1. Pretreatment: Take 18 kg of expanded perlite, high-pressure sterilization at 121°C for 25 min; take 17 kg of garden waste, crush to 2-5 mm, dry at 60°C to a moisture content of 9.6%, ready for use; Step 2. Mixing: weigh the chemical loose conditioner (modified sodium carboxymethyl cellulose 13 kg prepared in Example B, citric acid-malic acid complex organic acid 6 kg) and the biological stimulant (Bacillus subtilis exopolysaccharide 8 kg, seaweed extract 5 kg), and mix them in a double helix mixer at a speed of 160 r / min for 7 min; add the physical loose auxiliary agent, and reduce the speed to 110 r / min for mixing for 9 min; add the functional strains (Bacillus subtilis 10 kg, Bacillus mucilaginosus 4 kg) and sucrose fatty acid ester 3 kg, and mix them at a speed of 85 r / min for 4 min, and the product is obtained.

[0033] Example 8 The preparation method of the soil conditioner for large-scale production (1 ton formula) is as follows: Step 1. Pretreatment: take 200 kg of expanded perlite, and sterilize it at 121°C for 25 min; take 150 kg of garden waste, crush it to 2-5 mm, and dry it at 60°C until the water content is 9.6%, and reserve it; Step 2. Mixing: weigh the chemical loose conditioner (modified sodium carboxymethyl cellulose 150 kg prepared in Example B, citric acid-malic acid complex organic acid 80 kg) and the biological stimulant (Bacillus subtilis exopolysaccharide 100 kg, seaweed extract 70 kg), and mix them in a large double helix mixer at a speed of 190 r / min for 6 min; add the physical loose auxiliary agent, and reduce the speed to 130 r / min for mixing for 9 min; add the functional strains (Bacillus subtilis 120 kg, Bacillus mucilaginosus 60 kg) and sucrose fatty acid ester 50 kg, and mix them at a speed of 95 r / min for 4 min, and the product is obtained.

[0034] The products of the above examples all have no obvious caking, and the variation coefficient of the effective viable bacteria count is ≤5%, meeting the requirements of industrial production and actual application.

[0035] Example 9 Improvement of middle-aged street trees in non-paved areas This example is aimed at the middle-aged Chinese scholar trees (tree age 8 years) in the non-paved areas of urban trunk roads, and the initial detection indexes of the soil are as follows: porosity 12.2%, pH 8.2, conductivity 3.6 mS / cm, and organic matter content 1.1%.

[0036] Step 1. Selection of the conditioner: the soil conditioner prepared in Example 4 is used; Step 2. Application method: the application amount is 1000 g / tree, and it is scattered outside the tree crown projection, mixed with a light rake for 3-5 cm, covered with 1.5 cm of fine soil, and watered with 8 L / tree; 500 g / tree is added after 1.5 months.

[0037] 1. Soil porosity test: Sample collection: a cutting ring (volume V = 100 cm 3) Collect undisturbed soil of 15-20 cm soil layer, weigh the wet soil mass (m 湿 ); Test steps: dry at 105°C to constant weight, weigh the dry soil mass (m 干 ); Calculate the soil bulk density p = m 干 / V, porosity = (1-p / 2.65) x 100% (2.65 is the soil particle density, unit g / cm 3 ); Sampling requirements: take 3 core samples at each sample point, parallel test, relative deviation ≤2% is allowed.

[0038] 2. Soil pH test: Sample preparation: take soil of 15-20 cm soil layer, dry and pass through a 2 mm sieve, mix according to the soil-water ratio of 1:2.5 (mass-volume ratio), shake for 30 min (150 r / min), stand for 30 min; use a pH meter with an accuracy of ±0.01, calibrate with pH 4.00 and 6.86 standard buffer before testing; Sampling requirements: take 3 different site soils at each sample point, mix and test, 3 parallel tests, take the average value.

[0039] 3. Soil conductivity test: Sample preparation: same as pH test, mix according to the soil-water ratio of 1:5 (mass-volume ratio), shake for 30 min (150 r / min), stand for 30 min, filter and take the supernatant; use a conductivity meter with an accuracy of ±1 μS / cm, calibrate with 0.01 mol / L KCl standard solution (conductivity 1413 μS / cm at 25°C) before testing.

[0040] 4. Microbial colonization persistence test: Sample collection: collect soil of 15-20 cm soil layer at 7 days, 30 days, 60 days, and 90 days after modification, take 3 parallel samples (10 g each) at each sample point; use gradient dilution coating method, dilute the soil sample with sterile water to 10 -6 -10 -8 times, take 0.1 mL and coat on LB medium (formula: tryptone 10 g / L, yeast extract 5 g / L, NaCl 10 g / L, agar 15 g / L, pH 7.0), incubate at 30±1°C for 48 h and then count; Calculation method: viable bacteria count (CFU / g) = average colony count x dilution factor / sample mass, 3 parallel tests, take the average value.

[0041] Judgment standard: after 90 days of modification, the viable bacteria count should be ≥5 x 10 7 CFU / g.

[0042] 5. Soil aggregate structure ratio test: Sample preparation: Collect the soil of 15-20 cm soil layer after modification, remove roots, stones and other impurities, pass through an 8 mm sieve, and take 100 g for standby; Test steps: Put the sample into the granule analyzer, and use 5 mm, 2 mm, and 0.25 mm screen groups in turn. After soaking in water for 10 min, move the screen groups up and down for 2 min (frequency 30 times / min, amplitude 3 cm). Collect the soil in each screen layer, dry at 105°C to constant weight, and weigh the mass (recorded as m1, m2, and m3, corresponding to >5 mm, 2-5 mm, and 0.25-2 mm); Calculation method: Granular structure ratio (%) = (m1+m2+m3) / 100 x 100%, parallel test 3 times, relative deviation ≤3% is allowed.

[0043] Judgment standard: After 30 days of modification, the granular structure ratio should be ≥30%.

[0044] Modification effect: After 7 days, the porosity increased to 24.3%, pH 7.3, conductivity 1.7 mS / cm; after 30 days, the effective viable bacteria number was 1.3 x 10 8 CFU / g, organic matter 1.9%, soil granular structure ratio 34.8%; after 180 days, the new shoot growth increased by 18%; specifically, as shown in Figure 1 and Figure 2 , the changes of porosity, pH, conductivity and effective viable bacteria number.

[0045] Example 10 Modification of young trees in paving area This example is aimed at young Platanus orientalis (tree age 3 years) in the tree pool of the commercial street. The initial detection index of the soil is: porosity 11.3%, pH 5.8, conductivity 3.2 mS / cm, and organic matter content 0.9%.

[0046] Step 1. Selection of modifier: use the soil modifier prepared in Example 5; Step 2. Application method: dilute the modifier by 1:10, add 0.15% Tween-80, spray at a pressure of 0.25 MPa, and the dosage is 2.5 L / ㎡; cover with 1 cm of decomposed pine needles after spraying; add 250 g / plant after 1.2 months; Modification effect: after 7 days, the porosity was 22.5%, pH 6.6, conductivity 1.6 mS / cm; after 30 days, the effective viable bacteria number was 1.1 x 10 8 CFU / g, organic matter 1.7%; after 180 days, the new shoot growth increased by 16%.

[0047] Example 11 Modification of old trees in saline-alkali soil This example is directed to old Fraxinus chinensis (tree age 15 years) in saline-alkali soil beside suburban highway. The initial detection index of the soil is: porosity 10.2%, pH 8.8, conductivity 4.2 mS / cm, and organic matter content 0.7%.

[0048] Step 1. Selection of the amendment: the soil amendment prepared in Example 6 is used; Step 2. Application method: the application amount is increased by 25% (2000 g / tree), and after spreading, 5 cm of light harrowing, 2 cm of fine soil covering, and 10 L of watering per tree are performed; 1000 g / tree is added after 1.8 months; Improvement effect: 7 days later, the porosity is increased to 21.5%, the pH is decreased to 7.8, and the conductivity is decreased to 2.5 mS / cm; 30 days later, the effective viable bacteria number is 9 x 10 7 CFU / g, the organic matter is 1.5%, and the phosphorus solubilization amount is 17.8 mg / g; 180 days later, the yellowing rate of the tree leaves is decreased from 65% to 20%, and the new shoot germination amount is increased by 12%.

[0049] Example 12. Improvement of young trees in acidic and compacted soil This example is directed to young Cinnamomum camphora (tree age 2 years) in a rainy mountain city. The initial detection index of the soil is: porosity 11.4%, pH 5.2, conductivity 1.8 mS / cm, and organic matter content 0.8%.

[0050] Step 1. Selection of the amendment: the soil amendment prepared in Example 7 is used; Step 2. Application method: the application amount is 550 g / tree, 3 cm of light harrowing is performed for mixing, 1 cm of fine soil covering is performed, and 5 L of watering per tree is performed; regular drainage is performed to prevent waterlogging during the rainy season; 275 g / tree is added after 1.2 months; Improvement effect: 7 days later, the porosity is increased to 23.7%, the pH is increased to 6.5, and the conductivity is stabilized at 1.7 mS / cm; 30 days later, the effective viable bacteria number is 1.2 x 10 8 CFU / g, and the organic matter is 1.6%; 180 days later, the survival rate of the seedlings is increased from 72% to 98%, and the ground diameter is increased by 0.8 cm.

[0051] Comparative Example 1. Amendment without physical loosening auxiliary agent The formula is the same as Example 4 except that the expanded perlite and the crushed garden waste are removed, and the amendment is applied to the medium-aged Sophora japonica in Example 9.

[0052] Effect: 7 days later, the porosity is only increased to 18.1%, and 30 days later, it is decreased to 16%; the effective viable bacteria number is 6.0 x 10 7 CFU / g, which is significantly lower than that in Example 9.

[0053] Comparative Example 2. Amendment without protective agent The formula is the same as Example 4 except that the sucrose fatty acid ester is removed and applied to the middle-aged tree of Example 9.

[0054] Effect: 30 days later, the effective viable count is only 4.2 x 10 7 CFU / g.

[0055] Comparative Example 3: Modifier with deviated proportion of chemical loose conditioner The chemical loose conditioner in the formula is 5 kg of modified sodium carboxymethyl cellulose and 25 kg of citric acid-malic acid complex organic acid, and the rest is the same as Example 4, applied to the middle-aged tree of Example 9.

[0056] Effect: 7 days later, the porosity is only 15.9%, 30 days later, the pH drops to 6.0, and the leaves show slight curling.

[0057] Comparative Example 4: Modifier with missing biological stimulant The formula removes the extracellular polysaccharide of Bacillus subtilis and the seaweed extract, and the rest is the same as Example 4, applied to the middle-aged tree of Example 9.

[0058] Effect: 30 days later, the soil aggregate structure accounts for 18.2%, 180 days later, the porosity drops to 15.0%, and the new shoot growth increases by only 5%.

[0059] Comparative Example 5: Modifier with deviated proportion of biological stimulant The biological stimulant in the formula is 3 kg of extracellular polysaccharide of Bacillus subtilis and 18 kg of seaweed extract, and the rest is the same as Example 4, applied to the middle-aged tree of Example 9.

[0060] Effect: 30 days later, the soil aggregate structure accounts for 20.1%, 180 days later, the new shoot growth increases by 7%, which is much lower than the 18% of Example 9.

[0061] Comparative Example 6: Modifier with incompatible particle size of physical loose auxiliary agent The particle size of expanded perlite in the formula is changed to 5-8 mm, and the particle size of garden waste is changed to 10-15 mm, and the rest is the same as Example 5, applied to the young plane tree of Example 10.

[0062] Effect: After spraying, it blocks the gaps of water permeable bricks, 7 days later, the porosity is only 17.1%, 30 days later, the effective viable count is 3 x 10 7 CFU / g.

[0063] Comparative Example 7: Modifier with reversed proportion of strains The functional strains in the formula are 4 kg of ordinary Bacillus subtilis and 14 kg of Bacillus mucilaginosus, and the rest is the same as Example 6, applied to the old tree of Example 11.

[0064] Effect: 30 days later, the amount of phosphorus released was only 8.1 mg / g, the conductivity was 3.2 mS / cm, and the yellowing rate of the tree body did not decrease significantly.

[0065] Comparative Example 8: Improver with insufficient purity of biological stimulant raw material The content of algal extract alginate in the formula was reduced to 10%, and the rest was the same as Example 7. It was applied to the young Cinnamomum camphora in Example 12.

[0066] Effect: 30 days later, the soil aggregate structure accounted for 22.3%; 180 days later, the root length of the seedling was 30% shorter than that of Example 12, the ground diameter was only 0.4 cm thicker, and the survival rate decreased to 90%.

[0067] Comparative Example 9: Improver with incompatible HLB value of protective agent The protective agent in the formula was replaced with sucrose fatty acid ester with HLB value of 4-6, and the rest was the same as Example 7. It was applied to the young Cinnamomum camphora in Example 12.

[0068] 30 days later, the effective viable count was 2.0×10 7 CFU / g, and 180 days later, the survival rate of the seedling was only 85%, lower than 98% of Example 12.

[0069] Comparative Example 10: Improver containing only chemical loosening conditioner The formula only retained the chemical loosening conditioner (modified carboxymethyl cellulose sodium 15 kg + citric acid-malic acid complex organic acid 8 kg), removed the biological stimulant, physical loosening auxiliary agent, functional strain and protective agent, and the rest was the same as Example 4. It was applied to the middle-aged Sophora japonica in Example 9.

[0070] Effect: 7 days later, the porosity was only 18.2%, the pH decreased to 7.6, and the conductivity was 2.8 mS / cm; 30 days later, due to the lack of physical support, the clay particles were re-aggregated, the porosity fell to 15.5%, no obvious aggregate structure was formed, and the effective viable count was only 3.5×10 7 CFU / g, much lower than Example 9.

[0071] Comparative Example 11: Improver containing only physical loosening auxiliary agent The formula only retained the physical loosening auxiliary agent (expanded perlite 20 kg + crushed garden waste 15 kg), removed the chemical loosening conditioner, biological stimulant, functional strain and protective agent, and the rest was the same as Example 4. It was applied to the middle-aged Sophora japonica in Example 9.

[0072] Effect: 7 days later, the surface porosity increased to 20.1%, but the porosity at 15-20 cm depth was only 13.8%; 30 days later, the conductivity was still 3.1 mS / cm, the pH did not change significantly, and the effective viable count was 2.8×10 7 CFU / g, the soil physical and chemical properties did not improve, and the colonization of microorganisms was difficult.

[0073] Comparative Example 12: amendment containing only biological stimulant + functional strain The formula retains only the biological stimulant (Bacillus subtilis exopolysaccharide 10 kg + seaweed extract 7 kg) and functional strain (Bacillus subtilis 12 kg + Bacillus mucilaginosus 6 kg), removes the chemical loosening conditioner, physical loosening auxiliary agent and protective agent, and the rest is the same as Example 4. It is applied to the middle-aged sophora in Example 9.

[0074] Effect: After 7 days, there is no obvious improvement in porosity (12.5%), and clay particles are not dispersed, making it difficult for the strain to contact soil particles; after 30 days, the effective viable cell count is 8.6 x 10 7 CFU / g, the aggregate structure accounts for 21.3%, and the organic matter is only 1.5%; after 180 days, the new shoot growth is only increased by 6%, and it cannot achieve the synergistic effect of loosening and nutrient activation.

[0075] Comparative Example 13: amendment containing chemical + physical components The formula retains the chemical loosening conditioner (modified sodium carboxymethyl cellulose 15 kg + citric acid-malic acid complex organic acid 8 kg) and the physical loosening auxiliary agent (expanded perlite 20 kg + crushed garden waste 15 kg), removes the biological stimulant, functional strain and protective agent, and the rest is the same as Example 4. It is applied to the middle-aged sophora in Example 9.

[0076] Effect: After 7 days, the porosity is increased to 21.5%, the pH is 7.4, and the conductivity is 2.5 mS / cm; after 30 days, due to the lack of biological cementation, the aggregate structure accounts for only 23.7%, and the organic matter is 1.4%; after 180 days, the porosity falls to 17.2%, the soil structure stability is poor, and it cannot achieve long-term improvement.

[0077] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments, without departing from the spirit and technical solutions of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments according to the technical essence of the present application, all within the scope of the technical solutions of the present application, are still within the scope of protection of the present application.

Claims

1. A microbial soil amendment for in situ rejuvenation of street trees, characterized in that, By weight parts, including chemical loose conditioning agent, biological stimulant, physical loose auxiliary agent, functional strain and protective agent; The chemical loose conditioning agent consists of 13-17 parts of modified sodium carboxymethyl cellulose and 6-10 parts of citric acid-malic acid complex organic acid; The biological stimulant consists of 8-12 parts of Bacillus subtilis exopolysaccharide and 5-9 parts of seaweed extract; The physical loose auxiliary agent consists of 18-22 parts of expanded perlite and 13-17 parts of crushed garden waste; The functional strain consists of 10-14 parts of Bacillus subtilis and 4-8 parts of Bacillus mucilaginosus; The protective agent is 3-7 parts of food-grade sucrose fatty acid ester.

2. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The viscosity of the modified sodium carboxymethyl cellulose is ≤500 mPa·s, the water dissolution time at 25℃ is ≤30 min, and the dispersion clay particle rate is ≥50%; the mass ratio of citric acid to malic acid in the citric acid-malic acid complex organic acid is 2-3:1, and the concentration is 80%.

3. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The preparation method of the modified sodium carboxymethyl cellulose is: S1. Raw material pretreatment: take 100 parts by weight of refined cellulose, add 500-600 parts by weight of a mixed solvent of isopropanol and water with a mass ratio of 3:1, stir and disperse at a speed of 100-120 r / min for 15-20 min to form a uniform and stable suspension; S2. Alkalization reaction: place the suspension in a constant temperature water bath, cool to 20-25℃, slowly add 30-40 parts by weight of 45% sodium hydroxide solution, continue to stir for 60-90 min after the addition is completed, so that the cellulose is fully alkalized to form alkali cellulose, and the temperature fluctuation during the process should be controlled within ±2℃ to ensure uniform alkalization; S3. Etherification reaction: increase the temperature of the system to 55-60℃, add 40-50 parts by weight of 80% chloroacetic acid at a rate of 1-2 mL / min, control the dropping time to be 30-45 min, and then keep the reaction for 120-150 min, with stirring at 120-150 r / min during the period; S4. Neutralization and purification: after the reaction is completed, slowly add glacial acetic acid to the system to adjust the pH to 6.5-7.0 to terminate the reaction; centrifuge the reaction liquid at a speed of 3000 r / min for 10 min, collect the solid product, and wash it with a mixed solvent of isopropanol-water with a mass ratio of 2-3 times; S5. Drying and crushing: dry the washed solid product at 60-70℃ and -0.08 MPa until the water content is ≤8%, then take it out and crush it to a particle size of 0.1-0.5 mm with a super micro grinder to obtain modified sodium carboxymethyl cellulose.

4. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The molecular weight of the Bacillus subtilis exopolysaccharide is 10000-50000 Da; the content of alginic acid in the seaweed extract is ≥20%.

5. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The bulk density of the expanded perlite is ≤ 80 kg / m 3 The porosity is ≥ 75%; the pulverized garden waste is a harmless treatment product of green pruning branches and fallen leaves, and the cellulose content is ≥ 70%.

6. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The effective viable cell number of the Bacillus subtilis is ≥ 2 x 10 10 CFU / g, the low oxygen tolerance rate under 5% oxygen concentration is ≥ 65%; the effective viable cell number of the Bacillus mucilaginosus is ≥ 1 x 10 9 CFU / g, the salt tolerance rate under 4.0 mS / cm conductivity is ≥ 80%.

7. A microbial soil amendment for in situ rejuvenation of street trees according to claim 1, characterized in that, The HLB value of the food-grade sucrose fatty acid ester is 8-10.

8. The method of claim 1-7 for the preparation of a microbial soil amendment for in situ rejuvenation of street trees, characterized in that, The method comprises the following steps: (1) Pretreatment: sterilize the expanded perlite at 121℃ for 20-30 min, crush the garden waste to 2-5 mm and dry it at 60℃ until the water content is ≤10%; (2) Mixing: sequentially mix the chemical loose conditioning agent, biological stimulant, physical loose auxiliary agent, functional strain and protective agent in proportion, the rotation speed of double helix mixer is 150-200 r / min, 100-150 r / min and 80-100 r / min respectively, and the mixing time is 5-8 min, 8-10 min and 3-5 min respectively, to obtain the product.

9. The method of using the microbial soil amendment for in situ rejuvenation of street trees according to any one of claims 1 to 7, characterized in that, comprising the following steps: - non-paved area: the application amount of young trees is 450-550 g / tree, the application amount of middle-aged trees is 900-1100 g / tree, and the application amount of old trees is 1400-1600 g / tree, after spreading, the soil is lightly raked for 3-5 cm, covered with 1-2 cm of fine soil, and watered with 5-10 L / tree; - Paved area: 1:8-12 dilution of the amendment, 0.12-0.18% Tween-80, high pressure spray 2-3 L / m 2 , covered with 1-2 cm of composted pine needles; - later maintenance: water once every 5-7 days within 1 month after application, and add half of the amount of the modifier 1.2-1.8 months later.

10. The use according to claim 9, characterized in that, When the soil conductivity is > 3.5 mS / cm, the application amount is increased by 15%-25%; the soil moisture content is maintained at 20%-23% after application.

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