Method for repairing coal mine waste land through combination of plants and microorganisms

Abstract

The invention provides a method for jointly repairing a coal mine wasteland by using plants and microorganisms, and aims to promote vegetation recovery, reduce water and soil loss, reduce leaching water pollutants and soil heavy metal content, improve treatment efficiency and effectively improve the ecological environment of the coal mine wasteland through planting of Juncao and using of Juncao nitrogen-fixing bacterial fertilizer. Reutilization of the waste land is achieved, and a new thought and approach are provided for treatment of the coal mine waste land.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological management, and in particular relates to a method for repairing coal mine wasteland by utilizing plant-microorganism combination. Background Art

[0002] Abandoned coal mine land refers to land that has been severely damaged by coal mining activities and cannot be directly reused. The hazards of abandoned coal mine land involve multiple aspects such as ecological environment, geological disasters and social economy. In terms of ecological and environmental hazards: during coal mining, a large amount of vegetation is cut down or occupied, resulting in bare surface and aggravated soil erosion; at the same time, mining activities will change the soil structure, causing soil nutrient loss and pH imbalance; harmful substances in waste such as coal gangue may penetrate into the soil, causing heavy metal pollution, etc.; mine drainage and waste rock leaching water contain a large amount of harmful substances, which will seriously pollute water sources and affect the water safety of aquatic organisms and surrounding residents if discharged directly into the water body; ecological and environmental damage will also lead to the loss of animal and plant habitats, and biodiversity will be seriously threatened. Frequent geological disasters: after the underground coal seam is mined, the overlying rock layer loses support, and ground collapse and cracks are prone to occur; abandoned coal mine land is often steep, and coupled with vegetation destruction and soil erosion, it is prone to natural disasters such as landslides and mudslides. Socio-economic impacts: Abandoned coal mine land cannot be directly used for agriculture, forestry or urban construction, resulting in a waste of land resources; the management and restoration of abandoned coal mine land requires a large amount of capital, which brings an economic burden to local governments and enterprises; abandoned coal mine land not only affects the production and life of local residents, but may also have a negative impact on tourism, transportation and other industries in surrounding areas.

[0003] At present, the more common treatment measures for coal mine wasteland are: first cut the slope for treatment, then roll the slope in layers, cover it with loess, and then plant suitable plants according to the climate and environment. Traditionally, perennial plants such as fir, liquidambar formosana, Schima superba and Sapium sebiferum are generally selected. However, the traditional treatment method has the following shortcomings: first, these plants grow slowly, and the planting spacing is large, which cannot quickly increase the vegetation coverage. Their root system is thick and sparse, the number of root hairs at the root tip is small, and the ability to network soil and hold water is poor; second, planting trees requires 30cm~50cm of imported soil before it can be carried out. A large amount of imported soil will increase the cost of treatment, and the treatment funds in some areas are relatively small, which seriously affects the progress of coal mine wasteland treatment; finally, it is difficult to produce economic benefits in the short term by planting traditional plants, and it is impossible to achieve ecological industrialization. Therefore, the above measures cannot fully meet the requirements of efficient, fast, low-cost and sustainable ecological treatment. Summary of the invention

[0004] The purpose of the present invention is to provide a method for repairing coal mine wasteland by using plant-microorganism combined, which mainly utilizes five kinds of mushroom grasses with significantly different and complementary biological characteristics to form a systematic and fast-acting method for the treatment of coal mine wasteland.

[0005] To achieve the above object, the present invention adopts the following technical solution: A method for plant-microorganism combined restoration of coal mine wasteland, including engineering land preparation and mushroom grass planting, the specific operation is as follows: 1. Engineering land preparation 1.1 Soil reconstruction project (1) Slope protection: 1) Slope cutting and load reduction: Clean up the dangerous rock masses distributed on the top and surface of each section, that is, excavate and unload the dangerous rocks on the slope from top to bottom according to the original slope proportion, remove the dangerous rocks and level the platform at the foot of the slope; 2) Slope compaction: compact the unstable slope to make its dry density ≤1.67g / cm 3 ; (2) Site leveling: According to the terrain and other conditions, the table structure under different slopes is reasonably determined to ensure that the slope is solid and stable; the table design principles: ensure the safety and stability of the slope, convenient drainage of the table (3% inward inclination), and lay bamboo grooves in the slope to facilitate drainage; adapt to mechanized farming and construction requirements; (3) Imported soil: Different amounts of imported soil are used according to different governance objectives. If the governance objective is to combine ecological governance with industrial application, the thickness of the imported soil should be 20 ≤ ≤ 30 cm. If the governance objective is only ecological governance, only a small amount of imported soil or no imported soil can be used. 1.2 Supporting Projects (1) Water source project: To facilitate irrigation and watering in the later stage, water reservoirs are arranged according to the irrigation area; (2) Drainage works: 1) Rapid flow trough: Rapid flow troughs are set up on all levels of slopes to guide the water flow of the platform into the drainage ditch at the foot of the slope through the rapid flow trough; the width of the rapid flow trough is 1.0m, and it is in the shape of steps, which can also serve as maintenance steps; 2) Intercepting ditch: An intercepting ditch is set up at the rear edge of the treatment area to intercept surface water from entering the treatment area; the intercepting ditch is constructed with C25 shotcrete, and its cross section is trapezoidal, with a top width of 114cm, a bottom width of 50cm, and a height of 80cm; 3) Platform drainage ditch: In order to prevent the rainfall water collected on the slope from eroding the platform cover, a drainage ditch (including ground drainage ditch) is opened on the inner side of each level of platform; the drainage ditch is constructed with M10 mortar-laid flagstones, with a rectangular cross-section of 40cm wide and 40cm high; 2. Juncao planting Different methods of growing Juncao are used according to different governance objectives (ecological governance and industrial application areas that combine ecological governance with industrial application, and ecological governance areas that only carry out ecological governance); 2.1 Ecological governance and industrial application area (1) Platforms and slopes with a slope of ≤25°: Select two varieties of Juncao, Giant Juncao and Purple Elephant Grass, and plant them by seedling transplanting during the rainy season; specifically, the Giant Juncao seedlings and Purple Elephant Grass seedlings that have grown for 2 to 3 months and have 4 to 6 tillers are planted in holes according to fish scale contours, with a row spacing of 100 cm × 50 cm, a hole depth of 30 cm, and a hole diameter of 20 cm; before planting in the holes, add 20 g of Juncao nitrogen-fixing fertilizer, then remove the seedlings from the nutrient pots after cutting off the top leaves and place them vertically into the holes, cover with soil and compact, and water them enough to establish roots; Giant Juncao and Purple Elephant Grass are planted in strips, that is, Giant Juncao~Purple Elephant Grass~Giant Juncao..., and the number of rows planted in a single strip of Juncao varieties is not limited; (2) Slopes with a slope of 25°<slope<45°: Select two species of Juncao, namely, purple elephant grass and reed bamboo, and plant them by seedling raising and transplanting in the rainy season. Specifically, purple elephant grass seedlings that have grown for 2-3 months and have 4-6 tillers and reed bamboo seedlings that have grown for 3-5 months and have 3-5 tillers are planted in holes according to fish scale contour lines, with a row spacing of 150 cm×50 cm, a hole depth of 30 cm, and a hole diameter of 20 cm. Before planting in the holes, add 20 g of Juncao nitrogen-fixing fertilizer, then remove the seedlings from the nutrient pots after cutting off the top leaves and place them vertically in the holes, cover with soil and compact, and water them enough to establish roots. Giant Juncao, purple elephant grass, and reed bamboo are planted in rows, that is, one row of giant Juncao~one row of purple elephant grass~one row of reed bamboo~one row of giant Juncao...; (3) Slopes with a slope of ≥45°: Select two mushroom grass varieties, reed and bermudagrass, and plant them by seed spraying during the rainy season. Specifically, mix reed, bermudagrass with wood fiber, 18-18-18 compound fertilizer, mushroom grass nitrogen-fixing fertilizer, water retaining agent, and adhesive in a mass ratio of 10:10:200:50:50:5:1, and use a sprayer to spray evenly onto the slope. The spraying should be done from top to bottom to ensure that the grass seeds can be evenly covered on the slope. After spraying, cover the slope with a layer of non-woven fabric to maintain soil moisture and promote grass seed growth (the non-woven fabric needs to be fixed to prevent it from being blown away by the wind). After spraying, water and maintain in time to ensure the water supply of the grass seeds so that the grass seeds can grow into seedlings. When the seedlings grow to 5-6 cm or 2-3 leaves, remove the non-woven fabric and continue watering and maintenance until the vegetation completely covers the ground. 2.2 Ecological governance area (1) Areas with a slope of less than 45°: Three species of Juncao, namely, Giant Juncao, Purple Elephant Grass and Phyllostachys japonica, were selected and planted in the rainy season by seedling raising and transplanting. Specifically, the seedlings of Giant Juncao and Purple Elephant Grass that had grown for 2 to 3 months and had 4 to 6 tillers, and the seedlings of Phyllostachys japonica that had grown for 3 to 5 months and had 3 to 5 tillers were planted in holes according to the fish scale contour line, with a row spacing of 150 cm × 100 cm, a hole depth of 30 cm and a hole diameter of 20 cm. Before hole planting, 15 cm of loess was filled into the planting hole, and 20 g of Juncao nitrogen-fixing bacterial fertilizer was applied, and then covered with 5 cm of loess. After the top leaves of the seedlings were cut off, the nutrient pots were removed and placed vertically into the hole, and then covered with 10 cm of loess and compacted, and finally covered with a layer of coal slag. During planting, a clump of Phyllostachys japonica was placed in each planting hole with a clump of Giant Juncao or a clump of Purple Elephant Grass, and the two matching modes were planted in rows. After planting, sufficient water was poured to allow the roots to take root. (2) For slopes with a slope of ≥45°: the method for growing mushroom grass is the same as that in operation (3) in 2.1.

[0006] Wherein, the adhesive is FLOBOND A30.

[0007] In the present invention, five kinds of mushroom grass varieties, namely, giant mushroom grass, purple elephant grass, reed, reed and bermudagrass, are selected for planting. Among them, giant mushroom grass and purple elephant grass, which have fast growth rate, strong tillering ability, developed root system, tall plants and thick stems, can be used for rapid planting in ecologically fragile areas, water and soil conservation, soil improvement and landscape beautification. In addition, giant mushroom grass has high crude protein content and high nutritional value, and can be used as edible fungus culture medium, forage or processed into grass pulp, fiberboard and the like. Purple elephant grass has bright color and ornamental value, and can be used for beautifying the environment and can also be used as livestock forage, etc., so the following After harvesting, it can be used comprehensively to generate economic benefits; Phragmites australis, which has strong cold resistance, drought resistance, and burial pressure resistance, a well-developed root system, and tall plants, and can survive the winter at an extreme minimum temperature of -23°C, can be used in areas with thin soil layers, poor water retention, and low temperatures; seeds of perennial native plants such as reeds and dogtooth grass with full grains and no impurities can be directly sprayed and planted, and reeds have a well-developed root system and are cold and drought resistant, but they germinate and grow slowly in the early stages; and dogtooth grass grows faster in the early stages, but the plants are short, the root system is shallow, and they are not cold-resistant. The combination of the two can be used to restore vegetation on steep slopes. The combination of the five types of mushroom grass to repair coal mine wasteland can improve the adaptability and stress resistance of grasslands, enhance the stability of the ecosystem, and optimize the structure and function of grasslands.

[0008] At the same time, the combination of the five types of grass can enhance the adaptability of the grassland to different environmental conditions. The slopes with a slope of less than 45° are combined with warm-season giant grass, purple elephant grass and cool-season Phragmites australis, and the slopes with a slope of ≥45° are combined with warm-season bermudagrass and cool-season reed grass species, which can extend the green period of the abandoned mine land and keep it in a good growth state in different seasons.

[0009] In addition, there are differences in the root distribution and growth rate of the five types of mushroom grass. They grow together in the same ecosystem and can form a more stable and reasonable grassland structure. Giant mushroom grass and purple elephant grass both have fibrous root systems, and the roots are slender and dense, mainly distributed within 30-50 cm underground; the rhizomes of Phragmites australis are swollen and multi-noded, tough, and the fibrous fibrous roots are 80-150 cm deep in the soil; the root system of reed is very developed, extending 100-200 cm into the soil; the root system of dogtooth grass is dense and shallow, and can penetrate 10-30 cm into the soil. Therefore, for slopes with a slope of less than 45°, giant mushroom grass and purple elephant grass with dense fibrous root systems and fast growth are combined with Phragmites australis with thick roots that penetrate deep into the soil and slow growth; for slopes with a slope of ≥45°, reeds with roots that penetrate deep into the soil and dogtooth grass with shallow roots are combined, which can effectively prevent soil and water loss.

[0010] Planting giant fungus grass and purple elephant grass on platforms or slopes with a slope of less than 25° can not only effectively prevent soil erosion, but also produce good economic and ornamental value, making the function of the grassland more complete.

[0011] Therefore, the five species of Juncao have different growth habits and ecological niches. When they grow together in the same ecosystem, they can form a more complex community structure, thereby improving the stability and resistance of the ecosystem while increasing the biodiversity of the grassland ecosystem.

[0012] The significant advantages of the present invention are: Compared with planting traditional seedlings or planting a single variety of mushroom grass, the present invention uses a combination of multiple varieties of mushroom grass to repair abandoned coal mines. This composite planting model can effectively enhance the soil's ability to retain water and fertilizer, reduce soil erosion and leaching of pollutants; at the same time, the roots of the compositely planted mushroom grass can also improve the soil structure, effectively absorb pollutants in the leaching water, and reduce the harmful effects of the leaching water on the natural environment.

[0013] Experiments have shown that compared with planting single species of giant grass, purple elephant grass, reed bamboo and black pine, the water loss in the compound planting area of ​​grass and mushrooms was reduced by 75.6%, 75.3%, 86.3% and 95.7% respectively, with significant differences ( P <0.05), the total hardness and sodium content of leached water were the lowest, and the difference was significant (P<0.05); and the soil loss in the Juncao planting area was zero, and the soil holding effect was significantly different from that of the black pine planting area ( P<0.05); the manganese content in the leached water of the Juncao composite planting area was significantly different from that of the small black pine (P<0.05). It can be seen that the water retention effect is: Juncao composite planting> purple elephant grass> giant Juncao> reed bamboo> small black pine; soil holding effect: Juncao composite planting=giant Juncao=purple elephant grass=reed bamboo>small black pine; leached water quality: Juncao composite planting>purple elephant grass>giant Juncao>reed bamboo>small black pine, which proves that the Juncao composite planting model of the present invention is helpful for the restoration of coal mine wasteland. DETAILED DESCRIPTION

[0014] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0015] Example 1 1 Materials and methods 1.1 Test materials The mushroom grass used were giant mushroom grass, purple elephant grass and reed provided by the National Mushroom Grass Engineering Technology Research Center of Fujian Agriculture and Forestry University, and the seedlings used were small black pine from the Small Black Pine Seedling Nursery Company in Junan County.

[0016] 1.2 Overview of the Experimental Area In July 2023, a hillside was selected for testing in Xibei Village, Gaobei Town, Yongding District, Longyan City, Fujian Province. Yongding District has a subtropical marine monsoon climate with a mild climate all year round, an average annual temperature of 20.1℃, a frost-free period of 300 days, an average annual rainfall of about 1647mm, and relatively concentrated rainfall. The test site is an abandoned coal mine site, with yellow soil as the main soil, mixed with a large amount of coal gangue. Due to the steep slope, topsoil loss is very likely to occur.

[0017] 1.3 Experimental design Fifteen 30m2 projection areas were built at the test site. 2 The plot is 10 m × 3 m, with a slope of about 25°. Each plot is separated by cement slabs on all sides, and the lower part is connected to a 3 m × 1 m × 1 m flow collection pool to collect runoff and soil in the plot. There are 5 treatments in the experiment: ① giant fungus grass; ② purple elephant grass; ③ reed bamboo; ④ giant fungus grass, purple elephant grass, and reed bamboo three kinds of fungus grass composite strip planting; ⑤ small black pine. Each treatment has 3 replicates, and the spacing between rows and plants is 100 cm × 50 cm. The water volume observation period is from April 2024 to June 2024, and the soil and water loss of each plot is counted at the end of each month.

[0018] 1.4 Index determination (1) Water volume measurement: At the end of each month, measure the runoff pool, read the water level gauge, record the water volume, and then empty it.

[0019] (2) Determination of sediment volume: The sediment deposited in the runoff pond is measured at the end of each month and then emptied.

[0020] (3) Water quality determination: Water samples will be collected at the end of June 2024 to test the total hardness, manganese, sodium content and pH of the leached water.

[0021] 1.5 Data Analysis Excel 2016 data processing system and Graphpad Prism software were used for data analysis.

[0022] 2 Results and analysis 2.1 Effects of different treatments on water loss The determination and analysis results of water loss in different treatments of the experimental site from April to June 2024 are shown in Table 1.

[0023] Table 1 Water loss in different treatment plots from April to June 2024

[0024] As shown in Table 1, compared with the single species of giant grass, purple elephant grass, reed bamboo and black pine, the water loss in the compound planting area of ​​Juncao was reduced by 75.6%, 75.3%, 86.3% and 95.7% respectively, with significant differences ( P <0.05). This is because although giant grass and purple elephant grass have a large number of fibrous roots, they are mainly distributed within 30cm of the soil, while although the number of roots of Phragmites australis is relatively small, the roots are thick and can penetrate 50-80cm underground. The compound planting of Juncao fully utilizes the root distribution characteristics of giant grass, purple elephant grass, and Phragmites australis. The roots form a complementary structure within 80cm of the soil, which can absorb and store more water. In addition, the water loss in the Juncao planting area is significantly lower than that in the small black pine area ( P <0.05), indicating that Juncao has a clear advantage in water conservation on slopes. This is because Juncao grows fast and has a high vegetation coverage rate, which has a good effect on water conservation, while the small black pine grows slowly and has a low vegetation coverage rate, which is not conducive to water conservation. The average water conservation effect of the five treatments in the experiment was: Juncao composite planting > purple elephant grass > giant Juncao > reed bamboo > small black pine.

[0025] 2.2 Effects of different treatments on soil loss The determination and analysis results of soil loss under different treatments in the experimental site from April to June 2024 are shown in Table 2.

[0026] Table 2 Soil loss in different treatment plots from April to June 2024

[0027] As shown in Table 2, the soil loss in the Juncao planting area was 0kg, which was significantly lower than that in the Xiaohei pine area, indicating that Juncao has a clear advantage in soil retention on slopes. This is because Juncao plants grow fast and have a well-developed root system, which has a good soil retention effect in a short period of time, while the Xiaohei pine root system grows slowly, which is not conducive to soil retention. The average soil retention effect of the five treatments in the experiment was: Juncao composite planting = giant Juncao = purple elephant grass = reed bamboo > Xiaohei pine.

[0028] 2.3 Effects of different treatments on leaching water quality The determination and analysis results of the leaching water quality of different treatments in the experimental site in June 2024 are shown in Table 3.

[0029] Table 3 Leaching water quality determination in June 2024

[0030] From Table 3, we can see that the total hardness, sodium content and pH of leached water in the Juncao composite planting area are significantly different from those in the single species of giant Juncao, purple elephant grass, Phragmites australis and Pinus thunbergii ( P <0.05); the manganese content in the leached water of the Juncao compound planting area was significantly different from that of the black pine test group ( P <0.05), indicating that the Juncao composite planting model can reduce the impact of rain on slope soil through tall and dense above-ground plants, and at the same time make full use of the root distribution characteristics of giant Juncao, purple elephant grass and Phragmites australis, forming a complementary structure of roots within 80cm of the soil to absorb more water, thereby reducing the leaching effect of rain on pollutants. At the same time, Juncao can also absorb pollutants in water bodies, thereby reducing the harm of leaching water to the natural environment.

[0031] Example 2 1. Materials and Methods 1.1 Test materials Giant Juncao, Purple Elephant Grass, Phragmites australis seedlings and Juncao nitrogen-fixing bacterial fertilizer provided by the National Juncao Engineering Technology Research Center of Fujian Agriculture and Forestry University were selected. Juncao nitrogen-fixing bacterial fertilizer was prepared according to the literature "Effects of reducing chemical fertilizers and applying Juncao nitrogen-fixing bacterial fertilizer on giant Juncao growth, nutritional quality and soil nutrients" (Jia Yulei, Liao Zhen, Wang Lifang, et al. Acta Prataculturae Sinica, 2021, 30 (3): 215-223).

[0032] 1.2 Overview of the Experimental Area On March 1, 2024, a coal mine abandoned land platform was selected in Xibei Village, Gaobei Town, Yongding District, Longyan City, Fujian Province for testing. Yongding District has a subtropical marine monsoon climate with a mild climate all year round, an average annual temperature of 20.1℃, a frost-free period of 300 days, an average annual rainfall of about 1647mm, and relatively concentrated rainfall. The soil in the test site is mainly yellow soil, mixed with a large amount of coal gangue, and is relatively poor. Physical and chemical properties of the test soil: pH 4.65, organic matter 2.63 g / kg, total nitrogen 0.04 g / kg, alkaline nitrogen 3.60 mg / kg, available phosphorus 3.57 mg / kg, and available potassium 34.33 mg / kg.

[0033] 1.3 Experimental design Eighteen test sites with an area of ​​25 m 2 The plot was 5 m × 5 m in diameter, with a slope of about 25°. Each plot was separated by cement boards. There were 6 treatments in the experiment: ① giant grass + full fertilizer; ② giant grass + semi-quantitative fertilizer + grass nitrogen-fixing fertilizer; ③ purple elephant grass + full fertilizer; ④ purple elephant grass + semi-quantitative fertilizer + grass nitrogen-fixing fertilizer; ⑤ reed bamboo + full fertilizer; ⑥ reed bamboo + semi-quantitative fertilizer + grass nitrogen-fixing fertilizer (full fertilizer: urea 180 kg / hm 2 +Compound fertilizer 100 kg / hm 2 ; Semi-quantitative fertilizer: urea 90 kg / hm 2 +Compound fertilizer 50 kg / hm 2 , of which urea N ≥ 46.4%, compound fertilizer N (18) -P205 (18) -K2O (18) ≥ 54%; fungus grass nitrogen-fixing fertilizer: 250 kg / hm 2 ). Each treatment was set up with 3 replicates, arranged in completely randomized blocks, and the plant spacing was 100cm×50cm. All three types of Juncao were planted by seedling transplanting, and the experimental period was from March 1, 2024 to June 30, 2024.

[0034] 1.4 Index determination (1) Plant height and tillering: On June 30, 5 clumps were randomly selected from each plot for measurement; Fresh grass yield: On June 30, 5 m2 were randomly selected from each plot for measurement. 2 Conduct production measurement.

[0035] (2) Soil physical and chemical properties: On June 30, soil samples were randomly collected from each plot in equal amounts and mixed at multiple points for testing of physical and chemical properties.

[0036] 1.5 Data Analysis Excel 2016 data processing system and Graphpad Prism software were used for data analysis.

[0037] 2 Results and analysis

[0038] 2.1 Effects of combined application of bacterial fertilizer on plant height, tillering and yield of Juncao The results of the determination and analysis of the effects of applying bacterial fertilizer on the plant height, tillering and yield of the three types of Juncao are shown in Table 4.

[0039] Table 4 Effects of combined application of bacterial fertilizer on plant height, tillering and yield of Juncao

[0040] As shown in Table 4, the application of bacterial fertilizer promoted the plant height, tillering and yield of the three types of Juncao. Among them, the plant height and yield were significantly higher than those of the control group ( P <0.05). This is because the beneficial microorganisms in the bacterial fertilizer can decompose and release the nutrients fixed in the soil for crops to absorb and utilize, thereby promoting plant growth.

[0041] 2.2 Effects of bacterial fertilizer application on soil physical and chemical properties The results of the determination and analysis of the effects of bacterial fertilizer application on soil physical and chemical properties are shown in Table 5.

[0042] Table 5 Effects of combined application of bacterial fertilizer on soil physical and chemical properties

[0043] As shown in Table 5, compared with the control group, the contents of soil organic matter, total nitrogen and alkaline nitrogen were significantly increased after the three types of mushroom grass and bacterial fertilizer were applied ( P <0.05), the soil available phosphorus and quick-acting potassium contents were slightly higher than those in the control group, but the difference was not significant ( P >0.05), which proves that the application of bacterial fertilizer can help increase the density of soil microbial population, thus improving the soil microecological environment, increasing the content of soil available nitrogen, phosphorus and potassium, and ultimately significantly improving the fertilizer utilization rate of plants.

[0044] Application Example 1: This embodiment provides a method for treating abandoned coal mine land by taking the Banzhai Coal Mine in Xipi Village, Gaopi Town, Yongding District, Longyan City, Fujian Province as an example.

[0045] Yongding District, Longyan City, Fujian Province is rich in mineral resources, but large-scale mining in the past has damaged the ecological environment here. Coal mining in Yongding District has the characteristics of "small, scattered and chaotic" traditional small coal mines in the south. A large number of abandoned mines have been left over from history, causing certain ecological and environmental problems, restricting local economic and social development and ecological civilization construction, and affecting the production and living environment of 170,000 people in 6 coal-producing townships.

[0046] The research team of the National Juncao Center of Fujian Agriculture and Forestry University has selected Banzhai Coal Mine to carry out a trial of using Juncao to treat coal mine waste land since 2022, combining ecological treatment of coal mine waste land with the industrial application of Juncao, with a treatment area of ​​62 mu. The specific operation of the treatment method is as follows: 1. Engineering land preparation 1.1 Soil reconstruction project (1) Slope protection: 1) Slope cutting and load reduction: Clean up the dangerous rock masses distributed on the top and surface of each section, that is, excavate and unload the dangerous rocks on the slope from top to bottom according to the original slope proportion, remove the dangerous rocks and level the platform at the foot of the slope; 2) Slope compaction: compact the unstable slope to make its dry density ≤1.67g / cm 3 ; (2) Site leveling: According to the terrain and other conditions, the table structure under different slopes is reasonably determined to ensure that the slope is solid and stable; the table design principles: ensure the safety and stability of the slope, convenient drainage of the table (3% inward inclination), and lay bamboo grooves in the slope to facilitate drainage; adapt to mechanized farming and construction requirements; (3) Imported soil: 20 ≤ Imported soil thickness ≤ 30 cm; 1.2 Supporting Projects (1) Water source project: To facilitate irrigation and watering in the later stage, water reservoirs are arranged according to the irrigation area; (2) Drainage works: 1) Rapid flow trough: Rapid flow troughs are set up on all levels of slopes to guide the water flow of the platform into the drainage ditch at the foot of the slope through the rapid flow trough; the width of the rapid flow trough is 1.0m, and it is in the shape of steps, which can also serve as maintenance steps; 2) Intercepting ditch: An intercepting ditch is set up at the rear edge of the treatment area to intercept surface water from entering the treatment area; the intercepting ditch is constructed with C25 shotcrete, and its cross section is trapezoidal, with a top width of 114cm, a bottom width of 50cm, and a height of 80cm; 3) Platform drainage ditch: In order to prevent the rainfall water collected on the slope from eroding the platform cover, a drainage ditch (including ground drainage ditch) is opened on the inner side of each level of platform; the drainage ditch is constructed with M10 mortar-laid flagstones, with a rectangular cross-section of 40cm wide and 40cm high; 2. Juncao planting As the slope is 15°~25°, two varieties of Juncao, Giant Juncao and Purple Elephant Grass, were selected and planted by seedling raising and transplanting in the rainy season. Specifically, the Giant Juncao seedlings and Purple Elephant Grass seedlings that have grown for 2~3 months and have 4~6 tillers are planted in holes according to fish-scale contour lines, with a row spacing of 100cm×50cm, a hole depth of 30cm, and a hole diameter of 20cm. Before hole planting, 25g of Juncao nitrogen-fixing fertilizer is first put in, and then the seedlings with the top leaves cut off are removed from the nutrient pots and placed vertically in the holes. The soil is covered and compacted, and sufficient water is poured for rooting. The Giant Juncao and Purple Elephant Grass are planted in strips, i.e. Giant Juncao~Purple Elephant Grass~Giant Juncao..., and there is no limit to the number of rows planted in a single strip of Juncao varieties.

[0047] After six months of implementation according to the above steps, the height of the two varieties of Juncao, Giant Juncao and Purple Elephant Grass, reached 4m~5m, the aboveground biomass reached 8~15 tons / mu, and the vegetation coverage of the coal mine abandoned land increased to 80%~90%, with good planting effect and improved soil fertility. The planted Juncao can be harvested with stubble, and the harvested Juncao can be used as a culture medium for edible and medicinal mushrooms such as Oyster Mushroom and Shiitake Mushroom, as well as feed for livestock and poultry such as cattle, sheep, pigs, and geese, and can also be used as biomass energy, biomass materials, etc., to improve economic benefits.

[0048] We selected small black pines of the same size and planted them at the same time for comparative experiments. Three months after planting, we found that the amount of soil and water loss in the Juncao area was more than 92% less than that in the small black pine area. At the same time, the absolute enrichment of heavy metals in Juncao was 8 to 10 times that of the small black pine.

[0049] Application Example 2: This embodiment takes the FQ04 coal mine in Xibei Village, Gaobei Town, Yongding District, Longyan City, Fujian Province as an example to provide a method for utilizing and managing coal mine waste land.

[0050] The research team of the National Juncao Center of Fujian Agriculture and Forestry University has selected FQ04 coal mine to carry out the experiment of using Juncao to treat coal mine waste land since 2023, which is only used as a demonstration of ecological governance function, and the governance area is 186 mu. The specific operation of its governance method is as follows: 1. Engineering land preparation 1.1 Soil reconstruction project (1) Slope protection: 1) Slope cutting and load reduction: Clean up the dangerous rock masses distributed on the top and surface of each section, that is, excavate and unload the dangerous rocks on the slope from top to bottom according to the original slope proportion, remove the dangerous rocks and level the platform at the foot of the slope; 2) Slope compaction: compact the unstable slope to make its dry density ≤1.67g / cm 3 ; (2) Site leveling: According to the terrain and other conditions, the table structure under different slopes is reasonably determined to ensure that the slope is solid and stable; the table design principles: ensure the safety and stability of the slope, convenient drainage of the table (3% inward inclination), and lay bamboo grooves in the slope to facilitate drainage; adapt to mechanized farming and construction requirements; (3) Foreign soil: The thickness of foreign soil is 5-10 cm or there is no foreign soil; 1.2 Supporting Projects (1) Water source project: To facilitate irrigation and watering in the later stage, water reservoirs are arranged according to the irrigation area; (2) Drainage works: 1) Rapid flow trough: Rapid flow troughs are set up on all levels of slopes to guide the water flow of the platform into the drainage ditch at the foot of the slope through the rapid flow trough; the width of the rapid flow trough is 1.0m, and it is in the shape of steps, which can also serve as maintenance steps; 2) Intercepting ditch: An intercepting ditch is set up at the rear edge of the treatment area to intercept surface water from entering the treatment area; the intercepting ditch is constructed with C25 shotcrete, and its cross section is trapezoidal, with a top width of 114cm, a bottom width of 50cm, and a height of 80cm; 3) Platform drainage ditch: In order to prevent the rainfall water collected on the slope from eroding the platform cover, a drainage ditch (including ground drainage ditch) is opened on the inner side of each level of platform; the drainage ditch is constructed with M10 mortar-laid flagstones, with a rectangular cross-section of 40cm wide and 40cm high; 2. Juncao planting Since the slope is 30°~45°, three varieties of Juncao, namely, giant Juncao, purple elephant grass and reed bamboo, are selected and planted in the rainy season by seedling transplanting. Specifically, the giant Juncao and purple elephant grass seedlings that have grown for 2~3 months and have 4~6 tillers and the reed bamboo seedlings that have grown for 3~5 months and have 3~5 tillers are planted in holes according to fish scale contour lines, with a row spacing of 150cm×100cm, a hole depth of 30cm and a hole diameter of 20cm. Before hole planting, 15cm of loess is filled into the planting hole, and 20g of Juncao nitrogen-fixing fertilizer is applied, and then covered with 5cm of loess. Then, the seedlings with the top leaves cut off are removed from the nutrient pots and placed vertically into the hole, and then covered with 10cm of loess and compacted, and finally covered with a layer of coal slag. During planting, a clump of reed bamboo is placed in each planting hole with a clump of giant Juncao or a clump of purple elephant grass, and the two matching modes are planted in rows. After planting, sufficient rooting water is poured. After six months of implementation of the above steps, the plant heights of the three species of grass, giant grass, purple elephant grass and reed, reached 1.5m~2.0m, the aboveground biomass reached 2~3 tons / mu, and the vegetation coverage increased to 30%~50%; reeds and dogtooth grass grew well on slopes with a slope ≥45°, the vegetation coverage reached 70%~85%, and the planting effect was good.

[0051] We selected Chinese fir trees of the same size and planted them at the same time for comparative experiments. Three months after planting, we found that due to the lack of foreign soil and the foreign soil of only 5cm to 10cm in a small area, all the Chinese fir trees planted at the same time died, while all the Juncao trees survived and grew well; the amount of soil and water loss in the Juncao area was more than 90% less than that in the Chinese fir area.

[0052] Application Example 3: This embodiment provides a method for treating coal mine wasteland by taking Wangjiazhai Village, Panjiazhuang Town, Xingren County, Qianxinan Buyi and Miao Autonomous Prefecture, Guizhou Province as an example.

[0053] Xingren City is one of the 200 key coal-producing counties (cities) in the country. It is rich in coal resources, with proven coal reserves of about 3.65 billion tons and prospective reserves estimated to exceed 4.5 billion tons. This rich resource reserve provides a solid foundation for coal mining in Xingren City. However, solid wastes such as gangue generated during coal mining will form sewage containing heavy metals and harmful substances, namely leached water, under the scouring, leaching and soaking of rainwater. If these leached waters are directly discharged without proper treatment, they will cause serious pollution to the surrounding environment. After the leached water infiltrates into the soil, it will change the chemical properties of the soil, reduce soil fertility, and affect the growth and quality of crops. At the same time, the accumulation of heavy metals in the soil may also enter the human body through the food chain, posing a threat to human health.

[0054] The research team of the National Juncao Center of Fujian Agriculture and Forestry University has selected Xingli Coal Mine to carry out the Juncao treatment of coal mine waste land experiment since April 2023, combining the ecological treatment of coal mine waste land with the industrial application of Juncao, with a treatment area of ​​200 mu. The specific operation of its treatment method is as follows: 1. Engineering land preparation 1.1 Soil reconstruction project (1) Slope protection: 1) Slope cutting and load reduction: Clean up the dangerous rock masses distributed on the top and surface of each section, that is, excavate and unload the dangerous rocks on the slope from top to bottom according to the original slope proportion, remove the dangerous rocks and level the platform at the foot of the slope; 2) Slope compaction: compact the unstable slope to make its dry density ≤1.67g / cm 3 ; (2) Site leveling: According to the terrain and other conditions, the table structure under different slopes is reasonably determined to ensure that the slope is solid and stable; the table design principles: ensure the safety and stability of the slope, convenient drainage of the table (3% inward inclination), and lay bamboo grooves in the slope to facilitate drainage; adapt to mechanized farming and construction requirements; (3) Imported soil: 20 ≤ Imported soil thickness ≤ 30 cm; 1.2 Supporting Projects (1) Water source project: To facilitate irrigation and watering in the later stage, water reservoirs are arranged according to the irrigation area; (2) Drainage works: 1) Rapid flow trough: Rapid flow troughs are set up on all levels of slopes to guide the water flow of the platform into the drainage ditch at the foot of the slope through the rapid flow trough; the width of the rapid flow trough is 1.0m, and it is in the shape of steps, which can also serve as maintenance steps; 2) Intercepting ditch: An intercepting ditch is set up at the rear edge of the treatment area to intercept surface water from entering the treatment area; the intercepting ditch is constructed with C25 shotcrete, and its cross section is trapezoidal, with a top width of 114cm, a bottom width of 50cm, and a height of 80cm; 3) Platform drainage ditch: In order to prevent the rainfall water collected on the slope from eroding the platform cover, a drainage ditch (including ground drainage ditch) is opened on the inner side of each level of platform; the drainage ditch is constructed with M10 mortar-laid flagstones, with a rectangular cross-section of 40cm wide and 40cm high; 2. Juncao planting Since the slope is 20°~25°, two varieties of Juncao, Giant Juncao and Purple Elephant Grass, are selected and planted in the rainy season by seedling transplanting. Specifically, the giant Juncao seedlings and Purple Elephant Grass seedlings that have grown for 2~3 months and have 4~6 tillers are planted in holes according to fish scale contour lines, with a row spacing of 100cm×50cm, a hole depth of 30cm, and a hole diameter of 20cm. Before hole planting, 20g of Juncao nitrogen-fixing fertilizer is first put in, and then the seedlings with the top leaves cut off are removed from the nutrient pots and placed vertically in the holes, covered with soil and compacted, and watered enough to establish roots. Giant Juncao and Purple Elephant Grass are planted in strips, that is, giant Juncao~Purple Elephant Grass~Giant Juncao..., and the number of rows of a single strip of Juncao varieties is not limited. After one year of implementation of the above steps, the plant heights of the two species of Juncao, Giant Juncao and Purple Elephant Grass, reached 3m~4m (harvested once after 3 months of growth), and the aboveground biomass reached 15~20 tons / mu.

[0055] Chinese fir trees of the same size were selected for comparison. Six months after planting, it was found that the amount of soil and water loss in the Juncao area was more than 95% less than that in the Chinese fir area. At the same time, compared with the Chinese fir area, the total hardness, sulfate, nitrate, sodium and manganese content of the leached water in the Juncao area was significantly lower, with significant differences (P < 0.05).

[0056] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for remediating coal mine wasteland by combining plants and microorganisms, characterized in that: It includes two parts: engineering land preparation and mushroom grass planting; wherein, engineering land preparation includes the following operations:

1. Soil reconstruction project (1) Slope protection: 1) Slope cutting and load reduction: clean up the dangerous rock masses distributed on the top of each section and the slope surface; 2) Slope compaction: compact the unstable slope to make its dry density ≤1.67g / cm 3 ; (2) Site leveling: Level the table surface according to the terrain and make sure the slope is solid and stable; (3) foreign soil; 2. Supporting Projects (1) Water source project: laying out water reservoirs; (2) Drainage works: 1) Rapid flow trough: Rapid flow troughs are set up on all levels of slopes to guide the water flow from the platform into the drainage ditch at the foot of the slope through the rapid flow trough; 2) Intercepting ditch: A intercepting ditch is set up at the rear edge of the treatment area to intercept surface water from entering the treatment area; 3) Platform drainage ditch: In order to prevent the rainfall water collected on the slope from eroding the platform cover, a drainage ditch is opened on the inner side of each level of platform; The Juncao planting is carried out according to different management objectives:

1. Ecological governance and industrial application area (1) Platforms and slopes with a slope of ≤25°: Select two varieties of Juncao, Giant Juncao and Purple Elephant Grass, and use seedling transplanting to alternate strip planting during the rainy season; specifically, plant the Giant Juncao seedlings and Purple Elephant Grass seedlings with 4 to 6 tillers in holes according to the fish scale contour line, with a row spacing of 100 cm × 50 cm, a hole depth of 30 cm, and a hole diameter of 20 cm; before hole planting, add 20 g of Juncao nitrogen-fixing fertilizer, then cut off the top leaves of the seedlings and place them vertically into the hole, cover with soil and compact, and water enough to establish roots; (2) Slopes with a slope of 25°<slope<45°: Select two varieties of Juncao, namely, purple elephant grass and reed, and use the method of seedling raising and transplanting to alternately plant them in rows during the rainy season. Specifically, purple elephant grass seedlings with 4 to 6 tillers and reed seedlings with 3 to 5 tillers are planted in holes according to fish scale contour lines, with a row spacing of 150 cm × 50 cm, a hole depth of 30 cm, and a hole diameter of 20 cm. Before hole planting, add 20 g of Juncao nitrogen-fixing fertilizer, then vertically place the seedlings with the top leaves cut off into the hole, cover with soil and compact it, and water it enough to establish roots. (3) For slopes with a slope of ≥45°: Select two species of grass, reed and bermudagrass, and plant them by seed spraying during the rainy season. Specifically, mix reed and bermudagrass with wood fiber, 18-18-18 compound fertilizer, grass nitrogen-fixing fertilizer, water retaining agent, and adhesive, and spray them evenly on the slope. After spraying, cover the slope with a layer of non-woven fabric and water it in time to make the grass seeds grow into seedlings. When the seedlings grow to 5-6 cm or 2-3 leaves, remove the non-woven fabric and continue watering until the vegetation completely covers the ground.

2. Ecological governance area (1) Areas with a slope of less than 45°: Three species of Juncao, namely, Giant Juncao, Purple Elephant Grass and Phragmites australis were selected and planted by seedling raising and transplanting in the rainy season. Specifically, the seedlings of Giant Juncao and Purple Elephant Grass with 4 to 6 tillers and the seedlings of Phragmites australis with 3 to 5 tillers were planted in holes according to fish scale contour lines, with a row spacing of 150 cm × 100 cm, a hole depth of 30 cm and a hole diameter of 20 cm. Before hole planting, 15 cm of loess was filled into the planting hole, and 20 g of Juncao nitrogen-fixing bacterial fertilizer was applied, and then covered with 5 cm of loess. Then, the seedlings with the top leaves cut off were placed vertically into the hole, and then covered with 10 cm of loess and compacted, and finally covered with a layer of coal slag. During planting, a clump of Phragmites australis was placed in each planting hole with a clump of Giant Juncao or a clump of Purple Elephant Grass, and the two matching modes were planted in rows. After planting, sufficient water was poured to establish roots. (2) Slopes with a slope of ≥45°: The method of growing mushroom grass is the same as that for slopes with a slope of ≥45° in ecological management and industrial application areas.

2. The method for plant-microorganism combined restoration of coal mine wasteland according to claim 1, characterized in that: In the drainage project, the width of the rapids trough is 1.0m and it is stepped to serve as a maintenance step.

3. The method for plant-microorganism combined restoration of coal mine wasteland according to claim 1, characterized in that: In the drainage project, the intercepting ditch was constructed with C25 shotcrete; the cross-section of the intercepting ditch is trapezoidal, with a top width of 114cm, a bottom width of 50cm, and a height of 80cm.

4. The method for plant-microorganism combined restoration of coal mine wasteland according to claim 1, characterized in that: In the drainage project, the drainage ditch is constructed with M10 mortar-laid flagstones; the cross-section of the drainage ditch is rectangular, with a width of 40cm and a height of 40cm.

5. The method for plant-microorganism combined restoration of coal mine wasteland according to claim 1, characterized in that: In the Juncao planting on the slope with a slope of ≥45°, the mass ratio of reed, bermudagrass, wood fiber, 18-18-18 compound fertilizer, Juncao nitrogen-fixing fertilizer, water retaining agent and adhesive is 10:10:200:50:50:5:1; The adhesive is FLOBOND A30.

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