A low-sulfur coal gangue in-situ soilization method based on matrix maturation- seedling synchronization

Abstract

This invention discloses a method for in-situ soilification of low-sulfur coal gangue based on simultaneous substrate maturation and seedling cultivation. The method includes the following steps: (1) adding mineral soil to the raw coal gangue and mixing to obtain a raw coal gangue substrate layer; spreading an organic-inorganic compound improvement system and organic nutrient fertilizer on the raw coal gangue substrate layer and performing a first shallow tillage and mixing; then inoculating with functional compound microorganisms and performing a second shallow tillage and mixing for static maturation to obtain a matured coal gangue substrate; (2) transplanting pioneer plant seedlings directionally to the matured coal gangue substrate, performing directional planting, water management, and then cultivation to achieve the conversion of low-sulfur coal gangue into soil. This invention can achieve the in-situ conversion of low-sulfur coal gangue substrate into a primary soil-like substrate within 3 to 6 months.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of mine ecological restoration and soil science, and relates to a method for in-situ soilification of low-sulfur coal gangue based on simultaneous substrate maturation and seedling cultivation. Background Technology

[0002] Coal gangue is a solid waste generated during coal mining and washing. Its extreme physicochemical properties (acid-base imbalance, low nutrient content, and lack of biological activity) make it difficult for it to spontaneously form soil, becoming a core bottleneck for ecological restoration in mining areas. Among the main types of coal gangue, low-sulfur coal gangue (sulfur content <1% wt) is mainly composed of chemically inert minerals such as quartz, kaolinite, and illite, and contains a large amount of inert coal residue organic carbon, resulting in an extremely low rate of natural soil formation. Its main characteristics are: the matrix is ​​lumpy (requiring physical crushing for subsequent processing), extreme pH (around 3 in acidic matrices and above 9 in alkaline matrices), containing a large amount of aromatic ring-structured inert organic carbon, and lacking soil-forming driving factors. Therefore, the core bottleneck of in-situ soilification of low-sulfur coal gangue lies in how to simultaneously solve three problems: poor pH buffering stability, inert organic carbon activation barriers, and the lack of a plant-microbe synergistic soil-forming pathway.

[0003] The existing in-situ remediation technology for coal gangue has the following main shortcomings: (1) In the existing methods, pH regulation mostly relies on one-time neutralization, which fails to achieve long-term pH stability by increasing the buffer capacity, resulting in a common problem of pH rebound after neutralization; the microbial strains used are mostly general-purpose, lacking suitable bacterial groups screened for the environment of inert organic carbon (aromatic ring structure) in coal seams. (2) The substrate pretreatment and plant seedling cultivation are disconnected in terms of time sequence. The existing technology generally adopts the sequential mode of "completing substrate improvement first, then transplanting plants": if the seedlings are not ready after the substrate is matured, the substrate conductivity will rebound and the beneficial microbial population will decline during the waiting period; if forced transplanting is carried out, the root system will be damaged and the survival rate will be low. In addition, the existing seedling cultivation scheme relies on the cultivation substrate containing nutrient soil. The root washing operation during transplanting destroys the rhizosphere microecological structure, and the initiation of the rhizosphere effect is significantly delayed.

[0004] Currently, there is no in-situ soilification method that can precisely synchronize the maturation process of coal gangue matrix with the seedling cultivation process of pioneer plants and achieve immediate activation of rhizosphere effects. Summary of the Invention

[0005] The purpose of this invention is to provide an in-situ soilification method for low-sulfur coal gangue based on simultaneous substrate maturation and seedling cultivation, in order to solve the technical problems in existing methods such as poor pH buffer stability, lack of suitable microorganisms in coal seams, disconnect between substrate maturation and plant seedling cultivation, and damage to rhizosphere effects caused by transplanting and root washing, so as to realize the in-situ transformation of low-sulfur coal gangue substrate into primary soil-like substrate within 3 to 6 months.

[0006] This invention provides a method for in-situ soilification of low-sulfur coal gangue based on simultaneous substrate maturation and seedling cultivation. It constructs a ternary coupling method of "graded pretreatment - functional microbial maturation - pioneer plant rhizosphere-driven" and includes the following steps: (1) Add mineral soil to the raw coal gangue and mix to obtain the original coal gangue matrix layer; spread the organic-inorganic compound improvement system and organic nutrient fertilizer on the original coal gangue matrix layer and carry out the first shallow tillage and mixing; then inoculate functional compound microorganisms and carry out the second shallow tillage and mixing, and carry out static maturation to obtain the matured coal gangue matrix. (2) The pioneer plant seedlings are directionally transplanted to the matured coal gangue substrate, and directional planting and water management are carried out, and then cultivated to realize the conversion of low-sulfur coal gangue into soil.

[0007] In the above method, the mineral soil is mainly composed of primary silicate minerals, with a particle size of less than 2 mm and an organic matter content of less than 10%. The raw coal gangue is used after passing through a 2 mm sieve; The mass percentage of the mineral soil added to the raw coal gangue can be 5% to 15%.

[0008] In the above method, the organic-inorganic compound modification system consists of organic modification materials and inorganic modification agents. The inorganic modification agents include active layered silicate minerals, pH adjusting materials, and other inorganic modification agents, and the mass ratio of the three can be 1:0.5~2:0.25~2. The mass ratio of the organic modification materials to the inorganic modification agents can be 3~5:1. The organic modified material is selected from one or more of the following: corn stalks, wheat stalks, rice stalks, alfalfa stalks, rapeseed stalks, wood chips, and rice husks. The active layered silicate minerals are selected from montmorillonite, bentonite, or their mixtures; The pH adjusting material is selected from one or more of dolomite and lime; The other inorganic modifiers are selected from one or more of zeolite and phosphate rock powder; The organic nutrient fertilizer source is selected from one or more of cow manure compost, sheep manure compost, chicken manure compost, mushroom residue compost, and biogas residue compost; The amount of organic nutrient fertilizer added is 5% to 20% of the total mass of the organic improved materials.

[0009] In this invention, after the organic-inorganic compound improvement system is mixed, the carbon-nitrogen ratio of the entire matrix is ​​20~35:1.

[0010] In the above method, the functional composite microbial strain is composed of lignocellulose-degrading bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and sulfur-oxidizing bacteria; wherein, the lignocellulose-degrading bacteria are selected from Trichoderma and / or Aspergillus, the nitrogen-fixing bacteria are selected from at least one of Azotobacter, Rhizobium, and Beyerlinker, the phosphate-solubilizing bacteria are selected from at least one of Bacillus, Pseudomonas, and Arthrobacter, and the sulfur-oxidizing bacteria are selected from Thiobacillus. The effective viable count of the functional composite microbial strain is not less than 1.0 × 10⁻⁶. 8 CFU / g, inoculum size 80–150 g / m² 2 Based on the number of effective viable bacteria, the ratio of the lignocellulose-degrading bacteria: the nitrogen-fixing bacteria: the phosphate-solubilizing bacteria: the sulfur-oxidizing bacteria can be 1:(0.5-3):(0.5-3):(0.2-1), specifically 1:1:1:0.5.

[0011] In the above method, the mass percentage water content of the substrate during the static curing process can be 50% to 60%. The depth of both the first and second shallow tillage and mixing can be 20-30 cm; The pH of the matured coal gangue matrix can be 6.5 to 8.5, and the EC can be below 1.5 mS / cm.

[0012] In the above method, the ripening period can be 20 to 40 days; The seedling period for the pioneer plants can be 25 to 35 days; The time difference between the start of seedling cultivation of the pioneer plant seedlings in step (2) and the start of maturation in step (1) shall not exceed 3 days, so that the maturation progress is synchronized with the seedling cycle; the synchronized matching means that the substrate maturation cycle of 20 to 40 days and the seedling cycle of 25 to 35 days have an overlapping matching interval in the time window, so as to ensure that the seedlings meet the transplanting standards simultaneously when the substrate reaches the suitable state.

[0013] In the above method, the pioneer plant is selected from one or more of ryegrass, foxtail grass, bermudagrass, crabgrass, and Kentucky bluegrass; The pioneer plant species are selected based on the pH of the matured coal gangue matrix: when the pH of the matured coal gangue matrix is ​​>7.5, the pioneer plant is selected from one or more of ryegrass, foxtail grass and crabgrass; When the matured coal gangue matrix has a pH < 6.5 or is neutral, the pioneer plant is selected from one or more of ryegrass, bermudagrass, and Kentucky bluegrass.

[0014] In the above method, the seedling cultivation of pioneer plant seedlings in step (2) is carried out using an inert porous granular substrate as the seedling substrate.

[0015] In the above method, the inert porous particle matrix is ​​selected from one or more of river sand, quartz sand, and perlite; The seedling raising process of the pioneer plant seedlings in step (2) is as follows: the pioneer plant seeds are surface disinfected with 10% H2O2 for 10-15 min, germinated, and then sown in the cleaned inert porous granular substrate. During the seedling raising period, 1 / 2 Hoagland nutrient solution is applied, and the substrate moisture content is controlled by weighing to be 50%-60% of its maximum water holding capacity. The seedling conditions are as follows: daytime temperature 25±2℃, nighttime temperature 15±2℃, light intensity 12-14 h / d, and light intensity 3000-4000 lx; ​​the seedlings are irrigated with 1 / 2 Hogland's nutrient solution every 3-5 days.

[0016] The above method also includes a substrate acclimatization process during seedling cultivation: when the pioneer plant seedlings reach 5-8 cm, the matured coal gangue substrate obtained in step (1) is mixed into the seedling substrate at a constant rate, so that the volume ratio increases from 10% of the total amount to 20%-30% at a constant rate, and the acclimatization period is 7-14 days; by gradually increasing the contact ratio between the seedling roots and the coal gangue environment, the seedlings' tolerance to the physicochemical characteristics of the target substrate is enhanced.

[0017] In the above method, in step (2), the transplanting conditions for the pioneer plant seedlings are: the seedling height is 10-15 cm and the fibrous roots are intact, which is considered to be in a suitable state; when transplanting, the inert granular substrate around the roots is removed by shaking, and a thin layer of the inert granular substrate in the rhizosphere is retained on the surface of the roots, without washing the roots; wherein the amount of inert granular substrate retained is 5%-15% of the total mass of the seedling substrate, in order to maintain the continuity of the rhizosphere microecology and promote the rapid establishment of rhizosphere contact between the roots and the coal gangue substrate.

[0018] In the above method, in step (2), the planting density can be 12-18 plants / m². 2 ; When two different pioneer plants are used for mixed sowing, the ratio of plant number can be 1:1 to 2; The water management is as follows: immediately after planting, water is applied to settle the roots, and then precise water management is adopted to maintain the substrate moisture content at 50% to 60% of the maximum water holding capacity. No chemical fertilizers are applied throughout the soil formation cycle. The cultivation period is 3 to 6 months. When the pioneer plants continuously input organic matter into the substrate through root secretion and litter decomposition, the rhizosphere effect drives mineral weathering and nutrient activation. Functional microorganisms promote the decomposition of organic matter and the cementation of large aggregates, ultimately transforming the original coal gangue substrate into a primary soil-like substrate with good physical structure, chemical fertility and biological activity, providing a foundation for the subsequent natural succession of native vegetation.

[0019] In this invention, the precise moisture control includes the following two methods, which are selected according to the application scenario: (1) Laboratory / potted stage: The weighing method is used. First, the maximum water holding capacity of the substrate is measured. Based on this, the reference weight corresponding to the 50% to 60% water content is calculated. Weighing is done every 2 to 3 days. When the actual weight is lower than the reference range, deionized water is added to the reference weight range. (2) Field planting stage: Real-time monitoring of substrate volumetric water content, combined with the previously calibrated maximum water holding capacity, maintain the water content in the range of 50% to 60%, and monitor every 2 to 3 days; after natural rainfall, additional monitoring is carried out. When the water content exceeds 60% of the maximum water holding capacity, the water content is reduced by ventilation or light loosening. When the water content is below 50%, water is replenished at a uniform rate by drip irrigation or sprinkler irrigation.

[0020] In this invention, the soil obtained in situ in step (2) is a soil-like matrix formed after pretreatment with low-sulfur coal gangue organic-inorganic compound, synergistic colonization by functional microorganisms, and rhizosphere-driven growth by pioneer plants, and meets all of the following indicators: (a) Total organic carbon (TOC) content ≥9.5 g / kg, organic matter content ≥16.4 g / kg, total nitrogen (TN) content ≥0.75 g / kg, and carbon-nitrogen ratio (C / N) of 20–35:1; (b) The proportion of water-stable aggregates with a particle size greater than 0.25 mm is ≥30%, and the porosity is ≥33%; (c) Available potassium (AK) ≥50 mg / kg, available phosphorus (AP) ≥12 mg / kg.

[0021] The present invention has the following beneficial effects: 1. Enhanced pH buffering capacity: By introducing active layered silicate minerals (montmorillonite / bentonite) to construct a matrix buffering system, long-term stable regulation of extreme pH is achieved, rather than simply rebounding after neutralization, fundamentally solving the problem of insufficient pH toughness of low-sulfur coal gangue.

[0022] 2. Simultaneous maturation and seedling cultivation to eliminate time-sequence gaps: The substrate maturation and seedling cultivation are designed as a parallel process that starts and completes simultaneously, eliminating the problems of reverse deterioration of substrate properties and seedling aging and disuse caused by waiting in sequential operations, and significantly improving transplant survival rate and soil initiation efficiency.

[0023] 3. Substrate acclimatization seedling raising + rhizosphere medium retention, immediate activation of rhizosphere effect: Coal gangue is introduced in the later stage of seedling raising to acclimatize the seedling roots, and the rhizosphere medium is retained during transplanting. The two work together to enable the rhizosphere microorganisms of pioneer plants to establish functional contact with the coal gangue substrate in an immediate manner, effectively shortening the delay period of rhizosphere effect activation.

[0024] 4. Ternary Coupling Synergistic Soil Formation: Organic-inorganic compound modification provides carbon sources and improves physical structure; the functional microbial system suitable for coal seams (possessing the ability to decompose aromatic ring compounds) accelerates the activation of inert organic carbon and nutrient release; the rhizosphere effect of pioneer plants continuously drives mineral weathering and the formation of large aggregates. The synergistic effect of the three is significantly better than any single or pairwise combination. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the in-situ soilification method for coal gangue according to the present invention.

[0026] Figure 2 This is a comparison chart of the substrate and pioneer plant growth status of each treatment group after 4 months of pot experiment in Example 1 of the present invention.

[0027] Figure 3 This is a comparison chart of the substrate and pioneer plant growth status of each treatment group after 4 months of pot experiment in Example 2 of the present invention. Detailed Implementation

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0029] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0030] The present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0031] Example 1: Pot Cultivation Verification Experiment Using Alkaline Coal Gangue Substrate 1. Materials and Methods (1) Test coal gangue: The raw coal gangue (mainly primary silicate minerals, with a particle size of less than 2 mm and an organic matter content of less than 10%) was taken from a certain mining area, air-dried and passed through a 2 mm sieve; the basic properties are: pH = 9.2, EC = 501.1 μS / cm, TOC = 18.4 g / kg, AP = 3 mg / kg.

[0032] (2) Experimental design: A completely randomized design was adopted, with 5 treatment groups (control group CK and experimental groups T1-T4), and 4 biological replicates (n=4) for each treatment. Each pot contained 0.5 kg of substrate.

[0033] CK: Untreated coal gangue substrate, without any additives, microbial inoculation, or plant planting; water is maintained at 50% of maximum water holding capacity by weighing method. T1: Coal gangue matrix + organic-inorganic compound improvement system + organic nutrient fertilizer source + functional compound microbial system, no plants are planted, watering is done by weighing to maintain 50% of the maximum water holding capacity; T2: Coal gangue substrate + pioneer plant planting, no added organic or inorganic substances or microorganisms, watering by weighing to maintain 50% to 60% of maximum water holding capacity; T3: Coal gangue substrate + functional composite microbial system + pioneer plant planting, watering by weighing method to maintain 50% to 60% of maximum water holding capacity; T4: Coal gangue matrix + organic-inorganic compound improvement system + organic nutrient fertilizer source + functional compound microbial system + pioneer plant planting, watering by weighing method to maintain the maximum water holding capacity of 50% to 60%.

[0034] (3) Material and plant selection: The organic-inorganic compound amendment system is made by mixing organic amendment materials and inorganic amendments. The organic amendment materials are alfalfa straw and wood chips, and the inorganic amendments are bentonite, lime, and zeolite, with a mass ratio of 1:1:1; the organic-inorganic ratio is 3:1; and the total addition ratio is 4% (wt). The organic nutrient fertilizer source is cow manure compost and mushroom residue compost (specifically, it is the waste cultivation substrate after edible fungi harvest, which is used after being removed from the bag and crushed), with a mass ratio of 1:1. The amount added is 20% of the total mass of the organic improvement material, and the carbon-nitrogen ratio is adjusted to 20-35:1. The pioneer plant is ryegrass, with 4 plants planted in each pot.

[0035] (4) Substrate pretreatment and microbial inoculation: Prepare the original coal gangue substrate according to the method in (2) above, and add an organic-inorganic compound improvement system. The total amount of organic-inorganic compound improvement system and organic fertilizer added is 8 kg / m³. 2 The inoculation was performed using a functional composite microbial strain. All strains were diluted to an equal CFU concentration. The ratio of lignocellulose-degrading bacteria: nitrogen-fixing bacteria: phosphate-solubilizing bacteria: sulfur-oxidizing bacteria was 1:1:1:0.5, with corresponding volumes mixed. The inoculation amount was 100 g / m³. 2 The maximum water holding capacity of the substrate was determined to be 20%. After calculating the baseline weight, static cultivation was carried out for 30 days. The weight was weighed and water was added every 2 days to keep the weight within the baseline range.

[0036] (5) Seedling raising: River sand is used as the seedling substrate with a maximum water holding capacity of 32%. Water the seedlings precisely at a water content of 50% and raise the ryegrass seedlings for 20-30 days to obtain robust seedlings.

[0037] (6) Transplanting and cultivation: Transplant the seedlings into the pretreated coal gangue substrate, re-measure the total baseline weight of the potted plants, and cultivate them in a greenhouse (25℃) for 4 months. Weigh and water them every 2 days to maintain the weight within the baseline range and do not apply chemical fertilizers.

[0038] (7) Index determination: After cultivation, the physical and chemical properties, aggregate characteristics and microbial diversity of each group of substrates were determined to evaluate the formation effect of primary soil-like substrates.

[0039] 2. Results and Analysis After 4 months of cultivation, the core indicators of the substrate in each treatment group were as follows: Figure 2 As shown in Table 1.

[0040] Table 1

[0041] Note: TOC represents total organic carbon content, TN represents total nitrogen content, OM represents organic matter content, AP represents available phosphorus content, AK represents readily available phosphorus content, MI represents water-stable aggregates (WSA) with a particle size of 0.053-0.25 mm, MA represents water-stable aggregates (WSA) with a particle size greater than 0.25 mm, MAOM represents mineral-bound organic matter, and the data are the average of four replicates.

[0042] Example 2: Pot Experiment Verification Experiment with Acidic Coal Gangue Substrate 1. Materials and Methods (1) Test coal gangue: weathered coal gangue from a mining area was air-dried and passed through a 2 mm sieve; basic properties were: pH = 3.28, EC = 487.9 μS / cm, TOC = 350.1 g / kg, AP = 2 mg / kg.

[0043] (2) Experimental design: Same as in Example 1 of this invention, a completely randomized design was adopted, with 5 treatment groups: CK, T1, T2, T3, T4; each treatment was set up with 4 biological replicates (n = 4), and each pot contained 1.5 kg of substrate.

[0044] (2) Seedling raising: River sand is used as the seedling substrate with a maximum water holding capacity of 32%. The seedlings are precisely watered at a water content of 50% and the ryegrass seedlings are raised for 20 to 30 days to obtain robust seedlings.

[0045] (3) Transplanting and cultivation: Transplant the seedlings into the pretreated coal gangue substrate, re-measure the total baseline weight of the potted plants (the total weight of the potted plants after transplanting the seedlings excluding empty pots), and cultivate them in a greenhouse (25℃) for 4 months. Weigh and water them every 2 days to maintain the weight within the baseline range (using the weighing method, weighing before and after each watering, and maintaining the weight after watering at 50-60% of the substrate's saturated water holding capacity. That is, the weight after watering should be within the range of 1.5kg + (50-60% of the saturated water holding capacity) ± 10g). Do not apply chemical fertilizers.

[0046] (4) Index determination: After cultivation, the physical and chemical properties, aggregate characteristics and microbial diversity of each group of substrates were determined to evaluate the formation effect of primary soil-like substrates.

[0047] 2. Results and Analysis After 4 months of cultivation, the core indicators of the substrate in each treatment group were as follows: Figure 3 As shown in Table 2.

[0048] Table 2

[0049] Note: TOC represents total organic carbon content, TN represents total nitrogen content, OM represents organic matter content, AP represents available phosphorus content, AK represents readily available phosphorus content, MI represents water-stable aggregates (WSA) with a particle size of 0.053-0.25 mm, and MA represents water-stable aggregates (WSA) with a particle size greater than 0.25 mm. MAOM represents mineral-bound organic matter, and the data are the average of four replicates.

[0050] Based on the results of Examples 1 and 2 of this invention, compared with the blank control group CK, the complete treatment group (T4) of this invention achieved significant soil-like improvement in both alkaline (pH = 9.2) and acidic (pH = 3.28) low-sulfur coal gangue matrices: TOC, TN, and organic matter content were significantly increased; the proportion of large aggregates and micro-aggregates increased simultaneously, with the proportion of large aggregates (>0.25 mm) in the T4 treatment reaching 43.1% and 41.1%, respectively, both meeting the primary soil-like matrix quality standard of ≥30% in claim 13; porosity was significantly improved; and the matrix pH was stably adjusted to the suitable range for plants. Especially in the acidic matrix (Example 2), the T4 treatment effectively controlled the initial pH of 3.28 to 7.11 without rebound, demonstrating the core role of active layered silicate minerals in enhancing pH buffering capacity.

[0051] Compared with single treatment groups, the improvement effects of T1 (substrate improvement only) and T2 (pioneer plants only) are limited. In T3 (microorganisms + plants, no organic-inorganic improvement), the T4 standard is not fully met. This fully verifies the synergistic effect and broad applicability of the three-element coupling system of "graded pretreatment - functional microbial maturation - pioneer plant rhizosphere driving".

Claims

1. A method for in-situ soilification of low-sulfur coal gangue based on simultaneous substrate maturation and seedling cultivation, comprising the following steps: (1) Add mineral soil to the raw coal gangue and mix to obtain the original coal gangue matrix layer; spread the organic-inorganic compound improvement system and organic nutrient fertilizer on the original coal gangue matrix layer and carry out the first shallow tillage and mixing; then inoculate functional compound microorganisms and carry out the second shallow tillage and mixing, and carry out static maturation to obtain the matured coal gangue matrix. (2) The pioneer plant seedlings are directionally transplanted to the matured coal gangue substrate, and directional planting and water management are carried out, and then cultivated to realize the conversion of low-sulfur coal gangue into soil.

2. The method according to claim 1, characterized in that, The mineral soil is mainly composed of primary silicate minerals, with a particle size of less than 2 mm and an organic matter content of less than 10%. The raw coal gangue is used after passing through a 2 mm sieve; The mineral soil added to the raw coal gangue has a mass percentage of 5% to 15%.

3. The method according to claim 1 or 2, characterized in that, The organic-inorganic compound modification system consists of organic modification materials and inorganic modification agents. The inorganic modification agents include active layered silicate minerals, pH adjusting materials, and other inorganic modification agents, with a mass ratio of 1:0.5~2:0.25~2. The mass ratio of the organic modification materials to the inorganic modification agents is 3~5:

1. The organic modified material is selected from one or more of the following: corn stalks, wheat stalks, rice stalks, alfalfa stalks, rapeseed stalks, wood chips, and rice husks. The active layered silicate minerals are selected from montmorillonite, bentonite, or their mixtures; The pH adjusting material is selected from one or more of dolomite and lime; The other inorganic modifiers are selected from one or more of zeolite and phosphate rock powder; The organic nutrient fertilizer source is selected from one or more of cow manure compost, sheep manure compost, chicken manure compost, mushroom residue compost, and biogas residue compost; The amount of organic nutrient fertilizer added is 5% to 20% of the total mass of the organic improved materials.

4. The method according to claim 1 or 2, characterized in that, The functional composite microbial strain is composed of lignocellulose-degrading bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and sulfur-oxidizing bacteria; wherein, the lignocellulose-degrading bacteria are selected from Trichoderma and / or Aspergillus, the nitrogen-fixing bacteria are selected from at least one of Azotobacter, Rhizobium, and Beyerlinker, the phosphate-solubilizing bacteria are selected from at least one of Bacillus, Pseudomonas, and Arthrobacter, and the sulfur-oxidizing bacteria are selected from Thiobacillus. The effective viable count of the functional composite microbial strain is not less than 1.0 × 10⁻⁶. 8 CFU / g, inoculum size 80–150 g / m² 2 The ratio of the lignocellulose-degrading bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and sulfur-oxidizing bacteria, based on the effective viable bacteria count, is 1:(0.5-3):(0.5-3):(0.2-1).

5. The method according to any one of claims 1-4, characterized in that, The mass percentage moisture content of the substrate during the static curing process is 50%–60%. The depth of the first shallow tillage and the second shallow tillage is 20-30 cm. The matured coal gangue matrix has a pH of 6.5–8.5 and an EC of less than 1.5 mS / cm.

6. The method according to any one of claims 1-5, characterized in that, The ripening period is 20 to 40 days; The seedling period for the pioneer plants is 25 to 35 days; The time difference between the start of seedling cultivation of the pioneer plant seedlings in step (2) and the start of ripening in step (1) shall not exceed 3 days, so that the ripening progress is synchronized with the seedling cycle.

7. The method according to any one of claims 1-6, characterized in that, The pioneer plant is selected from one or more of ryegrass, foxtail grass, bermudagrass, crabgrass, and Kentucky bluegrass; The pioneer plant species are selected based on the pH of the matured coal gangue matrix: when the pH of the matured coal gangue matrix is ​​>7.5, the pioneer plant is selected from one or more of ryegrass, foxtail grass and crabgrass; When the pH of the matured coal gangue matrix is ​​<6.5 or neutral, the pioneer plant is selected from one or more of ryegrass, bermudagrass, and Kentucky bluegrass; The seedling cultivation of pioneer plants described in step (2) is carried out using an inert porous granular substrate as the seedling substrate.

8. The method according to claim 7, characterized in that, The inert porous granular matrix is ​​selected from one or more of river sand, quartz sand, and perlite; The seedling raising process of the pioneer plant seedlings in step (2) is as follows: the pioneer plant seeds are surface disinfected with 10% H2O2 for 10-15 min, germinated, and then sown in the cleaned inert porous granular substrate. During the seedling raising period, 1 / 2 Hoagland nutrient solution is applied, and the substrate moisture content is controlled by weighing to be 50%-60% of its maximum water holding capacity. The seedling conditions are as follows: daytime temperature 25±2℃, nighttime temperature 15±2℃, light intensity 12-14 h / d, and light intensity 3000-4000 lx; ​​the seedlings are irrigated with 1 / 2 Hoagland's nutrient solution every 3-5 days. And / or, the seedling raising process also includes a substrate acclimatization seedling raising process: when the pioneer plant seedlings reach 5-8 cm, the matured coal gangue substrate obtained in step (1) is mixed into the seedling substrate at a constant rate, so that the volume ratio increases from 10% of the total amount to 20%-30% at a constant rate, and the acclimatization period is 7-14 days.

9. The method according to any one of claims 6-8, characterized in that, In step (2), the transplanting conditions for the pioneer plant seedlings are as follows: the seedling height is 10-15 cm and the fibrous roots are intact; when transplanting, the inert granular substrate around the roots is removed by shaking, and a thin layer of the inert granular substrate in the root zone is retained on the root surface, without washing the roots; wherein the amount of inert granular substrate retained is 5%-15% of the total mass of the seedling substrate.

10. The method according to any one of claims 6-9, characterized in that, In step (2), the planting density is 12–18 plants / m². 2 ; When two different pioneer plants are used for mixed sowing, the ratio of plant number is 1:1 to 2; The water management is as follows: immediately after planting, water is applied to settle the roots, and then precise water management is adopted to maintain the substrate moisture content at 50% to 60% of the maximum water holding capacity. No chemical fertilizers are applied throughout the soil formation cycle. The culture period is 3 to 6 months.

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