Mud flat saline-alkali soil microorganism-plant-hydrogen-rich water synergistic improvement method and application

Abstract

The invention relates to a mud flat saline-alkali soil microorganism-plant-hydrogen-rich water synergistic improvement method and application in the technical field of environmental engineering. Aiming at the technical problems that an existing strain cannot be applied to improvement of heavy metal polluted saline-alkali soil and lacks a compound functional strain, the invention provides a ternary synergistic improvement method. Bacillus firmus L71 and mulberry enterobacter H41 are mixed according to the mass ratio of 1: 1 to prepare a complex microbial inoculant, the spore number is larger than or equal to 1 * 10 < 8 > / g, and the viable count is larger than or equal to 5 * 10 < 8 > cfu / mL; 50-100 kg of the microbial inoculum is applied per mu according to the saline-alkali degree of the soil in a grading manner, and the microbial inoculum is mixed with the straw crushed to 5-10 cm according to the proportion of 20% Hydrogen-rich water with the dissolved hydrogen concentration of 0.7-1.0 mg / L is adopted for irrigation treatment, and irrigation is conducted according to needs; and planting 10-15 suaeda salsa, suaeda salsa or pennisetum sinese salt-tolerant plants per square meter. According to the method, the total salt removal rate of the soil reaches 30% or above, the organic matter content is increased by 1.5-10%, the plant growth promoting rate reaches 40% or above, the heavy metal bioavailability is reduced by 35% or above, and efficient comprehensive treatment of the heavy metal-salt and alkali combined contaminated soil is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental engineering, in particular to a method for improving a tidal salt-alkali soil by using a combination of microorganisms, plants and hydrogen-rich water and an application thereof. BACKGROUND

[0002] The area of tidal salt-alkali soil in China is about 90 million mu, and the area of coastal salt-alkali soil is about 380 million mu. Tidal reclamation is an important way to alleviate the shortage of land resources and increase the area of arable land. Traditional salt-alkali soil improvement mainly uses physical improvement, chemical improvement and biological improvement methods.

[0003] After searching and analyzing, several related technical solutions were found in the field of salt-alkali soil improvement technology. CN111548800A discloses a microbial inoculant for improving salt-alkali soil, which uses a combination of five strains of Pseudomonas, Bacillus subtilis and the like, and is used with phosphorite gypsum. The inoculant mainly improves the soil nutrient status through the functions of microbial phosphorus and potassium release. CN117448008A discloses a high-efficiency green salt-alkali soil conditioner, which uses a combination of organic materials such as pine needle humus, puffed sheep manure and corn straw bioactive carbon. The soil improvement is achieved through drip irrigation technology. CN116554885A discloses a special improvement agent for heavy salt-alkali soil, which uses chemical components such as wood vinegar, chelated calcium and plant hormones. The improvement effect is achieved through ion replacement and pH adjustment.

[0004] However, the existing technology has the following deficiencies: first, the existing strains are mostly commercial strains, and their functions are relatively single, mainly focusing on the functions of phosphorus and potassium release. There is a lack of complex functional strains that have salt tolerance, growth promotion and heavy metal tolerance, which cannot be applied to the improvement of salt-alkali soil with heavy metal pollution risk; second, the existing technology mostly uses single or binary improvement methods, such as the combination of microorganisms and chemical improvement agents or organic matter and chemical improvement agents, lacking a systematic multi-element collaborative improvement system; third, the reclamation area of the tidal zone often brings Cd, As, Pb and other heavy metals into the soil due to the early use of uncomposted domestic sludge, municipal solid waste and the like, causing a combined stress environment of salt-alkali stress and heavy metal pollution. The existing technology mainly addresses single salt-alkali pollution, and less involves the comprehensive treatment of heavy metal-salt-alkali combined pollution; finally, the application of emerging auxiliary technologies such as hydrogen-rich water in soil improvement is still blank, and the existing technology uses conventional irrigation methods, lacking auxiliary means to enhance plant stress resistance. SUMMARY

[0005] The technical problem to be solved by the present application is that the existing strains cannot be applied to the improvement of salt-alkali soil with heavy metal pollution risk, lacking complex functional strains that have salt tolerance, growth promotion and heavy metal tolerance, and lacking comprehensive improvement technology for heavy metal-polluted soil in a salt-alkali environment.

[0006] To address the aforementioned technical problems, this invention provides a synergistic improvement method for saline-alkali soil in tidal flats, incorporating microorganisms, plants, and hydrogen-rich water. This method achieves comprehensive improvement of saline-alkali soil in tidal flats by constructing a ternary synergistic system of microbial communities, hydrogen-rich water treatment, and salt-tolerant plant cultivation. This synergistic improvement method leverages the bioremediation function of native salt-tolerant and growth-promoting microorganisms in tidal flats, combined with the soil activation effect of hydrogen-rich water and the ecological restoration capacity of salt-tolerant plants, forming a multi-level and multi-dimensional soil improvement technology system.

[0007] The core of the synergistic improvement method lies in the preparation of a highly active indigenous salt-tolerant and growth-promoting bacterial community from tidal flats. This community is composed of *Bacillus stolonifera* L71 (CGMCC No. 26877) and *Enterobacter mulberryii* H41 (CGMCC No. 26876) in equal mass ratios. The compound bacterial agent is prepared using a mixed fermentation process. After seed culture for 12 hours, fermentation is carried out at 32℃ and a rotation speed of 120–150 r / min for 10–12 hours to ensure that the obtained bacterial agent has a spore count of 1 × 10⁻⁶. 8 At least 100 cells / gram, while maintaining a viable count of 5 × 10⁻⁶. 8 CFU / mL or higher. During the preparation of the microbial agent, the fermentation broth is mixed with humic acid or straw powder carrier at a volume-to-weight ratio of 1:40–50 to obtain a solid microbial agent product.

[0008] This bacterial community possesses triple functional characteristics: salt tolerance, growth promotion, and heavy metal tolerance. It can grow and reproduce normally in a simulated soil environment with pH 8.5, temperature 25℃, and moisture content of 20%. The community is suitable for soil improvement in heavy metal-contaminated saline-alkali tidal flats with total Cd content not exceeding 3.0 mg / kg, total As content not exceeding 100 mg / kg, and total Pb content not exceeding 400 mg / kg.

[0009] The microbial agent is applied in the field by compounding it with organic materials. The prepared compound microbial agent is mixed with straw material crushed to a length of 5-10 cm at a ratio of 20% by weight of the straw. Different application strategies are adopted according to the degree of soil salinization: for slightly saline-alkali land with a pH of 8.0-8.5 and a total salt content of 5-6.5 g / kg, the application rate of the microbial agent is controlled at 50-60 kg / mu; for moderately to severely saline-alkali land with a pH of 8.5-9.0 and a total salt content of 6.5-8 g / kg, the application rate of the microbial agent is increased to 70-100 kg / mu. The straw application rate is controlled at 250-350 kg / mu, and a top dressing of the microbial agent is applied 30-45 days after the initial application, at a rate of 5-10 kg / mu, to maintain soil microbial activity and the sustainability of the soil improvement effect.

[0010] The hydrogen-rich water soil activation treatment is a key technical link of the synergistic improvement, and uses hydrogen-rich water with a dissolved hydrogen concentration of 0.7-1.0 mg / L to replace the conventional irrigation water.

[0011] The plant planting link selects salt-tolerant plant varieties such as Suaeda salsa, Suaeda salsa or Pennisetum sp. and plants them in the soil pretreated by the microbial agent and the hydrogen-rich water. 2 The plant planting density is controlled at 10-15 plants / m

[0012] The synergistic improvement method can achieve significant soil improvement effect, the removal rate of total soil salt content is more than 30%, the organic matter content is increased by 1.5-10%, the plant growth promotion rate is more than 40%, and the biological availability of heavy metals is reduced by more than 35%.

[0013] The application also provides a salt-tolerant and growth-promoting microbial group product for improving the soil of a tidal salt-alkali land, which contains the two functional strains of Bacillus firmus L71 and Enterobacter sp. H41, and has a spore number

[0014] ≥1×10 8 cfu / mL and a viable bacterial count ≥5×10 8 cfu / mL. The microbial group product uses humic acid or straw powder as a carrier material, and the culture solution and the carrier are prepared in a volume-weight ratio of 1:40-50.

[0015] The application further provides the application of hydrogen-rich water with a dissolved hydrogen concentration of 0.7-1.0 mg / L as a plant stress resistance enhancer in the improvement of the soil of a tidal salt-alkali land.

[0016] The application also provides a tidal salt-alkali soil improvement system, which comprises a tidal native salt-tolerant growth-promoting bacterial population preparation device, a hydrogen-rich water preparation device and a synergistic application device. The bacterial population preparation device comprises a fermenter, a culture medium preparation device and a bacterial agent forming device, and is used for preparing a composite bacterial agent containing Bacillus firmus L71 and Hafnia sp. H41; the hydrogen-rich water preparation device comprises an electrolytic cell, a hydrogen dissolver and a concentration detector, and is used for preparing hydrogen-rich water with a hydrogen concentration of 0.7-1.0 mg / L; and the synergistic application device comprises a bacterial agent and straw mixing device and a soil application device, and is used for applying the mixed bacterial agent and straw to the tidal salt-alkali soil with a pH value of 8.0-9.0 and a total salt content of 5-8 g / kg, so as to realize the synergistic improvement effect of microorganisms-plant-hydrogen-rich water.

[0017] The application has the following beneficial effects relative to the prior art:

[0018] 1. A microbial-plant-hydrogen-rich water ternary synergistic soil remediation system is constructed, and a synergistic effect of 1+1+1>3 is generated, the soil total salt removal rate reaches more than 30%, and the organic matter content is increased by 1.5-10%, which is significantly better than the effect of the existing single or binary improvement technology.

[0019] 2. A tidal native salt-tolerant growth-promoting bacterial population with the functions of salt tolerance, growth promotion and heavy metal tolerance is screened, and is suitable for the heavy metal contaminated tidal salt-alkali soil with a total Cd content of ≤3.0 mg / kg, a total Pb content of ≤400 mg / kg and a total As content of ≤100 mg / kg, and fills the technical blank of the improvement of the heavy metal contaminated salt-alkali soil.

[0020] 3. The hydrogen-rich water soil activation technology is applied to the salt-alkali soil improvement for the first time, the hydrogen molecules are used to adjust the soil oxidation-reduction potential, the soil microbial activity is activated, the hydrogen molecules are absorbed into the plant through the root system, the antioxidant enzyme system is activated, the plant SOD and POD enzyme activities are increased by more than 15%, and the plant stress resistance under the salt stress condition is significantly enhanced, and the plant growth promotion rate reaches more than 40%.

[0021] 4. The resource utilization of agricultural wastes such as straws is realized, the soil organic matter content is increased, the heavy metal bioavailability is reduced by more than 35%, and good economic and environmental benefits are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a microbial-plant-hydrogen-rich water synergistic improvement method flowchart of the embodiment of the application.

[0023] Figure 2 is a comparison data graph of the soil improvement effects of different treatments in the embodiment of the application. DETAILED DESCRIPTION

[0024] The application will be described in detail below with reference to the drawings and specific embodiments.

[0025] Example 1: The purpose of this example is to verify the application effect of the salt-tolerant growth-promoting bacterial group prepared by mixing Bacillus firmus L71 and Enterobacter mori H41 at a mass ratio of 1:1 in the improvement of heavy metal contaminated saline-alkali soil.

[0026] As shown in Figure 1 , the soil in the reclamation area of the tidal flat in Binzhou City, Jiangsu Province was selected as the test soil, and the basic physicochemical properties of the soil were as follows: pH 8.2, total salt content 6.2 g / kg, organic matter content 8.5 g / kg, total Cd content 2.8 mg / kg, total Pb content 350 mg / kg, and total As content 85 mg / kg.

[0027] Preparation of Bacillus firmus L71 (CCTCC No. 26877): A fermentation medium was used, which consisted of molasses 20 g / L, soybean meal powder 10 g / L, dipotassium hydrogen phosphate 1.0 g / L, NaCl 50 g / L, and pH 7.0. After 12 hours of seed culture, fermentation was carried out at a temperature of 32°C and a rotation speed of 120 r / min for 10 hours, and the spore number in the culture solution reached 1.2×10 8 cfu / mL. 8

[0028] Preparation of Enterobacter mori H41 (CCTCC No. 26876): A fermentation medium was used, which consisted of molasses 20 g / L, soybean meal powder 15 g / L, potassium dihydrogen phosphate 1.5 g / L, calcium carbonate 1.0 g / L, and pH 7.0. After 12 hours of seed culture, fermentation was carried out at a temperature of 32°C and a rotation speed of 150 r / min for 12 hours, and the viable bacterial count in the culture solution reached 5.5×10 8 cfu / mL.

[0029] Preparation of the compound microbial agent: L71 and H41 strain culture solutions were mixed at a mass ratio of 1:1, and mixed with humic acid carrier at a volume-weight ratio of 1:40 to prepare a solid compound microbial agent with a spore number of 1.1×10 8 cfu / mL. 8

[0030] Application of the microbial agent: The prepared compound microbial agent 75 kg / acre was mixed with crushed wheat straw 375 kg / acre (20% of the straw weight) with a length of 7 cm, and then applied to the soil with a depth of 15-20 cm, and mixed thoroughly.

[0031] ​​Hydrogen-rich water soil activation treatment: Hydrogen-rich water with a dissolved hydrogen concentration of 0.8 mg / L was used for irrigation, with an irrigation amount of 40 mm each time, once a week for 12 weeks. The hydrogen-rich water was prepared by electrolysis, and the dissolved hydrogen concentration was measured using a hydrogen detector (model DH-83A). Hydrogen molecules adjust the soil oxidation-reduction potential, affecting microbial metabolic activity, and are absorbed by the roots into the plant body, activating the antioxidant enzyme system.

[0032] Planting: Giant reed was planted 10 days after the application of the microbial agent, with a planting density of 12 plants / m 2 .

[0033] Test method: Soil pH was determined by potentiometry (NY / T 1377-2007), total salt content was determined by the oven-dried residue weight method (HJ 802-2016), organic matter content was determined by potassium dichromate oxidation (NY / T 1121.16-2006), heavy metal content was determined by atomic absorption spectrophotometry (HJ 491-2019), plant dry weight was determined by oven-drying and weighing, and enzyme activity was determined by spectrophotometry. Each group of experiments was set up with 3 replicates, and the data was statistically analyzed using SPSS software.

[0034] After 90 days of treatment, the changes in soil physicochemical properties were determined, and the results showed that the soil pH decreased to 7.8; the total salt content decreased to 4.3 g / kg (removal rate 30.6%), the organic matter content increased to 9.3 g / kg (increased by 9.4%) Figure 2 A); the bioavailability of Cd, Pb, and As in the soil decreased by 35%, 38%, and 36%, respectively; the aboveground dry weight of giant reed increased by 40.5% compared with the control group, the root activity increased by 35.2%, the SOD enzyme activity in the plant body increased by 15.8%, and the POD enzyme activity increased by 17.5%. Figure 2 The comparative data of different treatment methods on soil improvement effect are shown.

[0035] This example verifies the significant effect of the 1:1 mass ratio mixed preparation of the salt-tolerant growth-promoting indigenous microflora on the improvement of heavy metal contaminated saline-alkali soil, and proves that the microflora has the composite functions of salt tolerance, growth promotion, and heavy metal tolerance, supporting the technical solutions of claims 1-3.

[0036] Example 2: The purpose of this example is to verify the effect of different hydrogen-rich water concentrations on soil activation treatment, and to determine the most suitable dissolved hydrogen concentration range.

[0037] The same soil was selected from the same test area, and the basic physicochemical properties were the same as in Example 1.

[0038] Five hydrogen-rich water concentration gradients were set: 0.5 mg / L, 0.7 mg / L, 0.8 mg / L, 1.0 mg / L, 1.2 mg / L, and a conventional tap water control group. Three replicates were set for each group.

[0039] The composite microbial agent was prepared and applied in the same manner as in Example 1, and the microbial agent was applied at a rate of 75 kg / acre.

[0040] Hydrogen-rich water soil activation treatment: Different concentrations of hydrogen-rich water were used for irrigation, with each irrigation amount being 35 mm, once a week for 12 consecutive weeks.

[0041] Planting: Suaeda salsa was planted, with a planting density of 13 plants / m 2 .

[0042] After 90 days of treatment, the results were as follows:

[0043] 0.5 mg / L hydrogen-rich water treatment: soil total salt removal rate 28.1%, plant growth promotion rate 35.5%, SOD enzyme activity increased by 12.2%;

[0044] 0.7 mg / L hydrogen-rich water treatment: soil total salt removal rate 30.7%, plant growth promotion rate 40.6%, SOD enzyme activity increased by 15.3%;

[0045] 0.8 mg / L hydrogen-rich water treatment: soil total salt removal rate 32.2%, plant growth promotion rate 43.9%, SOD enzyme activity increased by 16.7%;

[0046] 1.0 mg / L hydrogen-rich water treatment: soil total salt removal rate 33.8%, plant growth promotion rate 45.2%, SOD enzyme activity increased by 18.4%;

[0047] 1.2 mg / L hydrogen-rich water treatment: soil total salt removal rate 32.9%, plant growth promotion rate 44.8%, SOD enzyme activity increased by 17.8%;

[0048] Conventional tap water control: soil total salt removal rate 25.3%, plant growth promotion rate 28.1%, SOD enzyme activity showed no significant change;

[0049] The results show that Figure 2 B), the concentration of hydrogen-rich water is in the range of 0.7-1.0 mg / L, and the improvement effect gradually increases with the increase of the concentration, and the best effect is achieved at 1.0 mg / L, and the effect slightly decreases when the concentration exceeds 1.0 mg / L. Through this example, the most suitable dissolved hydrogen concentration range for hydrogen-rich water soil activation treatment is determined to be 0.7-1.0 mg / L, and the technical solutions of claim 4 and claim 9 are verified.

[0050] Example 3: The purpose of this example is to verify the effect of the grading treatment of the amount of microbial agent applied under different degrees of soil salinity.

[0051] Two types of soil were selected, i.e. light salinized soil (pH 8.1, total salt content 5.8 g / kg) and medium and heavy salinized soil (pH 8.7, total salt content 7.2 g / kg). Three replicates were set for each group.

[0052] The preparation method of the compound microbial agent was the same as in Example 1.

[0053] Grading application treatment:

[0054] Light salinized soil: the amount of microbial agent applied was set at 45 kg / acre, 50 kg / acre, 55 kg / acre, 60 kg / acre, 65 kg / acre, respectively,

[0055] 65 kg / acre;

[0056] Medium and heavy salinized soil: the amount of microbial agent applied was set at 65 kg / acre, 70 kg / acre, 80 kg / acre, 90 kg / acre, 100 kg / acre, respectively.

[0057] 100 kg / acre;

[0058] Hydrogen-rich water soil activation treatment: hydrogen-rich water with a dissolved hydrogen concentration of 0.8 mg / L was used, with an irrigation amount of 40 mm each time, once a week.

[0059] Planting: Suaeda salsa was planted, with a planting density of 14 plants / m 2 .

[0060] The results were determined after 90 days of treatment:

[0061] Light salinized soil:

[0062] 45 kg / acre: total salt removal rate 25.5%, organic matter increased by 6.1%;

[0063] 50 kg / acre: total salt removal rate 28.8%, organic matter increased by 7.6%;

[0064] 55 kg / acre: total salt removal rate 31.3%, organic matter increased by 8.9%;

[0065] 60 kg / acre: total salt removal rate 32.7%, organic matter increased by 9.3%;

[0066] 65 kg / acre: total salt removal rate 33.1%, organic matter increased by 9.8%;

[0067] Medium and heavy salinized soil:

[0068] 65 kg / acre: total salt removal rate 22.2%, organic matter increased by 5.7%;

[0069] 70 kg / acre: total salt removal rate 25.6%, organic matter increased by 6.9%;

[0070] 80 kg / acre: total salt removal rate 28.8%, organic matter increased by 8.2%;

[0071] 90 kg / acre: total salt removal rate 31.5%, organic matter increased by 9.7%;

[0072] 100 kg / acre: total salt removal rate 32.2%, organic matter increased by 10.0%;

[0073] The results show that the mild saline-alkali soil has a significant improvement effect in the range of 50-60 kg / acre of bacterial agent, and the effect is limited when the amount exceeds 60 kg / acre; the moderate to severe saline-alkali soil has the best improvement effect in the range of 70-100 kg / acre of bacterial agent. This example determines the optimal range of bacterial agent application for different saline-alkali soils and verifies the technical solution of hierarchical application in claim 1.

[0074] Example 4: The purpose of this example is to verify the stability and persistence of long-term treatment effect.

[0075] The same treatment scheme as in Example 1 is used, and the observation period is extended to 12 months, and the soil physical and chemical properties and plant growth conditions are measured every 3 months.

[0076] The results measured after 12 months of treatment: the soil pH is stable in the range of 7.7-7.9, the total salt content is maintained at 4.0-4.5 g / kg (removal rate remains above 30%), and the organic matter content is stable in the range of 9.0-9.5 g / kg. The plant growth-promoting effect remains stable, with an increase of 38%-42% in aboveground dry weight compared to the control group. The survival rate of the strain in the soil remains above 85%, and the activity is maintained well.

[0077] This example verifies the long-term stability and persistence of the technical solution, proving that the improvement effect can be maintained for a long time.

[0078] Comparative Example 1: The purpose of this comparative example is to verify the effect of soil activation treatment without hydrogen-rich water on the improvement effect.

[0079] The same composite bacterial agent and straw treatment as in Example 1 is used, but conventional tap water is used instead of hydrogen-rich water, and other conditions remain the same. Each group has 3 replicates.

[0080] After 90 days of treatment, the results showed that the soil pH decreased to 8.0, the total salt content decreased to 4.8 g / kg (removal rate 22.6%), and the organic matter content increased to 9.0 g / kg (an increase of 5.9%). The dry weight of the upper part of the giant seaweed meadow increased by 28.2% compared with the control group. The activities of plant antioxidant enzymes did not change significantly, SOD enzyme activity increased by only 3.1%, and POD enzyme activity increased by 5.8%.

[0081] Compared with Example 1 ( Figure 2 A) The lack of hydrogen-rich water soil activation treatment led to an 8.0 percentage point decrease in total soil salt removal rate, a 12.3 percentage point decrease in plant growth promotion rate, and a significant reduction in the increase in plant antioxidant enzyme activity. The comparison shows that hydrogen-rich water soil activation treatment plays a crucial role in the ternary synergistic soil remediation system and is a necessary technical step to achieve efficient soil improvement.

[0082] Comparative Example 2: The purpose of this comparative example is to verify the difference in the effect of using commercial strains to replace the native salt-tolerant and growth-promoting bacteria of tidal flats.

[0083] A commercially available compound of Bacillus subtilis and Pseudomonas aeruginosa was used, with the viable count adjusted to the same level as in Example 1. The application rate was the same as in Example 1, and other treatment conditions were consistent. Three replicates were set up for each group.

[0084] After 90 days of treatment, the soil pH decreased to 8.1, total salt content decreased to 5.2 g / kg (removal rate 16.1%), and organic matter content increased to 8.8 g / kg (an increase of 3.5%). Under heavy metal pollution conditions, the survival rate of commercial strains significantly decreased to 65%, the improvement effect was unstable, and the plant growth promotion rate was only 25.8%.

[0085] Compared with Example 1 ( Figure 2 A) The total salt removal rate of the soil treated with commercial strains decreased by 14.5 percentage points, the increase in organic matter decreased by 5.9 percentage points, and the plant growth promotion rate decreased by 14.7 percentage points. The comparison shows that commercial strains have poor adaptability to heavy metal-polluted saline-alkali soil environments, lack heavy metal tolerance, and their improvement effect is significantly lower than that of native salt-tolerant and growth-promoting bacteria in tidal flats. This demonstrates the superiority and environmental adaptability of the native multifunctional strains screened in this invention.

[0086] Comparative Example 3: The purpose of this comparative example is to verify the difference in effects between single strain treatment and complex bacterial group treatment.

[0087] Both were treated with a single Bacillus stolonifer L71 and a single Enterobacter mulberry H41, with an application rate of 75 kg / mu for both treatments. Other conditions were the same as in Example 1. Each group was set up with 3 replicates.

[0088] Results after 90 days of treatment:

[0089] Single L71 treatment: soil pH decreased to 7.9, total salt content decreased to 4.6 g / kg (removal rate 25.8%), organic matter content increased to 8.9 g / kg (increased by 4.7%), plant growth promotion rate was 32.6%, and heavy metal bioavailability decreased by 28%-32%.

[0090] Single H41 treatment: soil pH decreased to 8.0, total salt content decreased to 4.9 g / kg (removal rate 21.0%), organic matter content increased to 9.1 g / kg (increased by 7.1%), plant growth promotion rate was 28.9%, and straw degradation rate was 85%.

[0091] Comparison with the complex bacterial population treatment of Example 1: L71 single treatment is better in heavy metal fixation, but not as good as complex treatment in organic matter promotion and plant growth promotion; H41 single treatment is outstanding in straw degradation and organic matter promotion, but not as good as complex treatment in salt removal and heavy metal treatment; the complex bacterial population treatment is better than single strain treatment in all indicators, which reflects the synergistic advantage of 1:1 mass ratio mixing.

[0092] It is verified by comparison that the salt-tolerant growth-promoting bacterial population prepared by mixing Bacillus firmus L71 and Enterobacter mori H41 at a mass ratio of 1:1 has the functions of complementation and synergistic effect.

[0093] Comparative Example 4: The purpose of this comparative example is to verify the difference in effect between the traditional chemical improvement method and the ternary synergistic soil remediation system of the present application.

[0094] Gypsum modifier was used at a dosage of 1000 kg / acre, combined with conventional organic fertilizer 500 kg / acre, and conventional irrigation was used, and the same plants were planted. Three replicates were set for each group.

[0095] After 90 days of treatment, the results showed that the soil pH decreased to 8.3, the total salt content decreased to 5.4 g / kg (removal rate 12.9%), and the organic matter content increased to 8.7 g / kg (increased by 2.4%). Plant growth was affected by heavy metal stress, and the growth promotion effect was limited, with an increase in aboveground dry weight of only 15.7%.

[0096] Comparison with Example 1 ( Figure 2 A), the total salt removal rate of the traditional chemical improvement method was 17.7 percentage points lower, the organic matter promotion amplitude was 7.0 percentage points lower, and the plant growth promotion rate was 24.8 percentage points lower. Through comparison, it can be seen that the traditional chemical improvement method has limited effect in treating heavy metal-saline-alkali composite contaminated soil, and cannot solve the problem of multiple environmental stress at the same time, which proves the technical advantages and innovation of the ternary synergistic soil remediation system of the present application.

[0097] Based on the above examples and comparative examples, the application constructs a microbial-plant-hydrogen-rich water ternary synergistic soil remediation system, screens a salt-tolerant growth-promoting bacterial community of beach indigenous bacteria, and first applies the hydrogen-rich water soil activation technology to the field of soil improvement, thereby realizing efficient comprehensive management of heavy metal contaminated saline-alkali soil. Compared with the prior art, the improvement effect of the application is significantly improved, the soil total salt removal rate reaches more than 30%, the organic matter content is increased by 1.5-10%, the plant growth promotion rate is more than 40%, and the heavy metal bioavailability is reduced by more than 35%. Meanwhile, the application fills the technical blank of heavy metal-saline-alkali combined pollution treatment, and embodies remarkable novelty and creativity.

Claims

1. A method for improving the soil of a tidal salt-alkali land by synergistically using microorganisms, plants and hydrogen-rich water, characterized in that, Comprising the following steps: Step one: preparation of salt-tolerant and growth-promoting indigenous microbial flora in beach soil, Bacillus firmus L71 and Enterobacter cloacae H41 are mixed and fermented at a mass ratio of 1:1 to prepare a compound microbial agent with a spore number of ≥1×10 8 cfu / g and a viable bacterial count of ≥5×10 8 cfu / mL; Step two: application of the bacterial agent, the composite bacterial agent is mixed with straw crushed to 5-10 cm in length at a ratio of 20% of the weight of the straw, and then applied to the soil of the tidal salt-alkali land, wherein the mild salt-alkali land is soil with a pH value of 8.0-8.5 and a total salt content of 5-6.5 g / kg, the bacterial agent is applied at a rate of 50-60 kg / acre, the moderate to severe salt-alkali land is soil with a pH value of 8.5-9.0 and a total salt content of 6.5-8 g / kg, and the bacterial agent is applied at a rate of 70-100 kg / acre; Step three: hydrogen-rich water soil activation treatment, hydrogen-rich water with a dissolved hydrogen concentration of 0.7-1.0 mg / L is used for irrigation treatment of the soil, the irrigation amount is 30-50 mm each time, and the treatment is carried out once a week to replace the conventional irrigation water; Step four: planting of plants, planting of Suaeda salsa, Halocnemum strobilaceum or Puccinellia distans salt-tolerant plants in the treated soil, planting density of 10-15 plants / m 2 Planting is performed 7-14 days after the application of the bacterial agent. The preservation number of the Bacillus firmus L71 is CGMCC No. 26877, and the preservation number of the Enterobacter cloacae H41 is CGMCC No. 26876. Both strains have salt tolerance, growth promotion, and heavy metal tolerance functions.

2. The method according to claim 1, wherein the method is characterized by, The heavy metal tolerance concentration of the tidal soil indigenous salt-tolerant growth-promoting bacterial group in a simulated soil environment with a pH of 8.5, a temperature of 25°C, and a water content of 20% is: total Cd content ≤3.0 mg / kg, total Pb content ≤400 mg / kg, and total As content ≤100 mg / kg, and it is suitable for heavy metal contaminated tidal salt-alkali land soil.

3. The method according to claim 1, wherein the method is characterized by, The preparation of the complex bacterial agent comprises: after seed culture for 12 hours, fermentation culture is carried out at a temperature of 32 DEG C and a rotating speed of 120-150 r / min for 10-12 hours, so that the number of spores is greater than or equal to 1*10 8 cfu / g, and the number of living bacteria is greater than or equal to 5*10 8 cfu / mL; the culture solution is mixed with humic acid or straw powder carrier at a volume-weight ratio of 1:40-50 of the culture solution to the carrier, so as to obtain a solid bacterial agent.

4. The method according to claim 1, wherein the method is characterized by, The dissolved hydrogen concentration of the hydrogen-rich water soil activation treatment is 0.7-1.0 mg / L. Hydrogen molecules adjust the oxidation-reduction potential of the soil, activate the soil microbial activity, and are absorbed into the plant body through the root system, activate the antioxidant enzyme system, and after 30 days of treatment, the SOD and POD enzyme activities of the plant are increased by more than 15% compared with the control group.

5. The method according to claim 1, wherein the method is characterized by, The straw dosage is 250-350 kg / acre, and the bacterial agent is applied 30-45 days after the bacterial agent is applied, and the application amount is 5-10 kg / acre.

6. The method for improving the saline-alkali soil of tidal flat by the cooperation of microorganism, plant and hydrogen-rich water according to claim 1, characterized in that, The method achieves a soil total salt removal rate of ≥30%, an organic matter content increase of 1.5-10%, a plant growth promotion rate of ≥40%, and a heavy metal bioavailability reduction of ≥35%.

7. A halophilic growth promoting indigenous bacterial flora for soil improvement of a tidal salt-alkali soil, characterized in that, The bacterial flora contains Bacillus firmus L71 and Enterorhabdus mulberry H41, wherein the preservation number of Bacillus firmus L71 is CGMCC No.26877, and the preservation number of Enterorhabdus mulberry H41 is CGMCC No.26876; the bacterial flora has a spore number of ≥1×10 8 per gram and a viable bacterial number of ≥1×10 ≥ 5 x 10 8 cfu / mL, the culture fluid was mixed with the carrier in a volume-weight ratio of 1:40-50.

8. The salt-tolerant, growth-promoting bacterial population of indigenous coastal soil of claim 7, wherein, The carrier material is humic acid or straw powder, and the strain has salt tolerance, growth promotion, and heavy metal tolerance functions, and is suitable for heavy metal contaminated tidal salt-alkali land soil with a total Cd content of ≤3.0 mg / kg, a total Pb content of ≤400 mg / kg, and a total As content of ≤100 mg / kg.

9. The application of hydrogen-rich water with a dissolved hydrogen concentration of 0.7-1.0 mg / L as a plant stress resistance enhancer in the improvement of tidal flat saline-alkali soil, characterized in that, The hydrogen-rich water is used in conjunction with the tidal soil indigenous salt-tolerant growth-promoting bacterial group to adjust the oxidation-reduction potential of the soil through hydrogen molecules, activate the soil microbial activity, and improve the antioxidant enzyme activity of the plant.

10. A system for improving soil in a tidal saline environment, the system comprising: Comprising: The beach native salt-tolerant growth-promoting microbial population preparation device comprises a fermentation tank, a culture medium preparation device and a microbial agent forming equipment, is used for preparing a compound microbial agent containing Bacillus firmus L71 and Enterobacter cloacae H41; the hydrogen-rich water preparation device comprises an electrolytic tank, a hydrogen dissolver and a concentration detector, and is used for preparing hydrogen-rich water with a dissolved hydrogen concentration of 0.7-1.0 mg / L; the synergistic application device comprises a microbial agent and straw mixing device and a soil application device, and is used for applying the mixed microbial agent and straw to the beach saline-alkali soil with a pH value of 8.0-9.0 and a total salt content of 5-8 g / kg; wherein the system realizes the synergistic improvement effect of microorganisms-plant-hydrogen-rich water.

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