Soil conditioner and uranium mine area vegetation restoration method

Abstract

The soil conditioner provided by the invention has the advantages of high ripening speed, economy, safety and stability when being used for ripening raw soil in the uranium mine area. The soil conditioner is used for soil ripening, then herbaceous plants are sown, and effective improvement of uranium mine area soil is achieved. The physical structure, chemical characteristics and biological activity of soil are remarkably improved, the soil structure is improved, the water and fertilizer maintaining capacity is improved, heavy metal pollution is reduced, the plant survival rate is increased, and plant growth is promoted, so that vegetation recovery is achieved.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration technology, specifically relating to a soil conditioner and a method for vegetation restoration in uranium mining areas, and more specifically to a soil conditioner and a method for restoring vegetation ecology in uranium mining areas after mining using ryegrass plants. Background Technology

[0002] Currently, common soil ripening technologies are mainly divided into physical ripening, chemical ripening, and biological ripening. Physical ripening techniques include topsoil introduction, timely tillage, plowing, land leveling, sand application, irrigation canals, and vertical irrigation. Physical ripening is a long process and requires a large workload. Chemical ripening mainly refers to ripening raw soil using chemical amendments. Most current research on soil ripening focuses on mining areas, especially coal and stone mining areas, for soil function restoration and farmland soil improvement. Common amendments include humic acid, high-molecular-weight water-retaining agents, desulfurized gypsum, biochar, fly ash, coal gangue, steel slag, zeolite powder, sepiolite, and other natural or synthetic amendments. Biological ripening techniques can be divided into plant-based and microbial-based methods. Plant-based methods utilize the inherent characteristics of plants, such as their ability to accumulate heavy metals and their soil-loosening effects, to improve the soil. Microbial-based methods involve adding microbial agents to the soil to promote the mineralization of soil nutrients and increase porosity, thereby improving the soil's overall quality. Although research on soil maturation has been conducted for many years, the overall theoretical framework is mature, and the technical methods are abundant. However, current methods for maturing raw soil mostly rely on single soil conditioners, which have long lead times and limited improvement capabilities. Composite soil conditioners, on the other hand, lack theoretical support regarding the influence of individual materials, and the mixing amount and effect are unclear, making them unsuitable for achieving rapid maturation of raw soil in uranium mining areas.

[0003] Therefore, it is necessary to further develop a maturation method that can rapidly mature and plant the native soil in uranium mining areas, is easy to obtain, inexpensive, non-toxic and non-polluting, uses low-cost physical measures, effectively prevents soil erosion, and incorporates widely adaptable and ecologically beneficial plants. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a soil conditioner. Using this conditioner for soil maturation, followed by the sowing of herbaceous plants, the native soil in uranium mining areas can be effectively improved within one year. This improves the soil's physical structure, chemical properties, and biological activity, thereby enhancing soil structure, increasing water and fertilizer retention capacity, reducing heavy metal pollution, improving plant survival rates, and promoting plant growth, ultimately achieving the goals of creating vegetated landscapes or land reclamation. The developed native soil maturation soil conditioner also features rapid maturation, greater economy, and safety and stability.

[0005] The purpose of this invention is to provide a soil conditioner, which includes a water-retaining agent, wood ash, and biochar.

[0006] The water-retaining agent is linear anionic polyacrylamide with a particle size of 40-100 mesh, preferably 50-90 mesh, and more preferably 60-80 mesh.

[0007] In a preferred embodiment, the weight ratios of the water-retaining agent, wood ash, and biochar are as follows: the water-retaining agent is 0.05-0.3 parts by weight, the wood ash is 0.3-0.9 parts by weight, and the biochar is 0.5-1.5 parts by weight.

[0008] The plant ash is obtained by burning a mixture of herbaceous and / or woody plants in an aerobic atmosphere.

[0009] The biochar is obtained by pyrolysis of rice husks in an anaerobic atmosphere at 500-800℃, preferably 600-700℃. The biochar comprises 0.5-1.5 parts by weight.

[0010] The present invention also aims to provide a method for vegetation restoration in uranium mining areas. The method involves first mixing raw soil and mature soil in the uranium mining area at a weight ratio of 1:1, then using the soil conditioner described in this invention to improve the mixed soil, laying it on the area to be restored for maturation, and then planting herbaceous plants.

[0011] The method specifically includes the following steps:

[0012] Step 1. Mix the raw soil and mature soil from the uranium mine area at a weight ratio of 1:1 to obtain a raw-mature mixed soil;

[0013] Step 2. Mix the soil conditioner, fertilizer, and the raw and mature soil mixture obtained in Step 1 to obtain backfill soil;

[0014] Step 3. The backfill soil is laid on the area to be restored for maturation, and then grass seeds are sown to allow the grass seeds to develop and grow, thus restoring the vegetation in the uranium mining area.

[0015] The present invention has the following beneficial effects:

[0016] (1) The soil conditioner provided by this invention can be used for soil maturation, improve soil water and fertilizer retention capacity, and improve soil structure. Its raw materials are inexpensive and easy to obtain. Using this soil conditioner for soil maturation results in faster maturation of raw soil, which is more economical, safe and stable.

[0017] (2) The present invention utilizes the soil conditioner to mature the mixture of raw soil and mature soil, which significantly improves the physical structure, chemical properties and biological activity of the soil and greatly shortens the maturation time, thus providing a basis for the effective improvement of raw soil in uranium mining areas within one year.

[0018] (3) While the soil conditioner matures the soil, the present invention also uses the planting of herbaceous plants, such as ryegrass, to further improve the soil structure, enhance water and fertilizer retention capacity, reduce heavy metal pollution, increase plant survival rate and promote plant growth, thereby realizing the restoration of vegetation in uranium mining areas. Attached Figure Description

[0019] Figure 1 A comparison chart showing the pH values ​​of backfill soil E1-E9 and uranium mine native soil (CK) after the harvest of plants in Example 3 is shown.

[0020] Figure 2 The diagram shows a comparison of the available phosphorus content (AP) of the backfill soil E1-E9 after the harvest of plants in Example 3 and the raw soil (CK) of the uranium mining area.

[0021] Figure 3 The diagram shows a comparison of the available nitrogen (AN) and total nitrogen (TN) content in the backfill soil E1-E9 after the harvest of plants in Example 3 and the raw soil (CK) in the uranium mining area;

[0022] Figure 4 The diagram shows a comparison of the organic matter (OM) content of the backfill soil E1-E9 after the harvest of plants in Example 3 and the raw soil (CK) of the uranium mining area.

[0023] Figure 5 The diagram shows a comparison of plant height, dry weight, and total nitrogen (TN) content of the backfill soil E1-E9 and the uranium mine native soil (CK) in Example 3.

[0024] Figure 6 The photo shows the vegetation restoration in Example 2. Detailed Implementation

[0025] The present invention will now be described in detail through specific embodiments, and the features and advantages of the present invention will become clearer and more explicit with these descriptions.

[0026] This invention provides a soil conditioner comprising a water-retaining agent, wood ash, and biochar.

[0027] The water-retaining agent is linear anionic polyacrylamide with a particle size of 40-100 mesh, preferably 50-90 mesh, and more preferably 60-80 mesh.

[0028] The plant ash is obtained by burning a mixture of herbaceous and / or woody plants in an aerobic atmosphere.

[0029] The biochar is obtained by pyrolysis of rice husks under an anaerobic atmosphere at 500-800℃, preferably 600-700℃. Preferably, the anaerobic atmosphere is nitrogen and / or argon. In this invention, linear anionic polyacrylamide is used as a water-retaining agent, which has the functions of water absorption, water retention, and fertilizer retention. Its specific structure enhances the soil's water-fixing capacity and retains nutrients, providing a favorable water and fertilizer environment for crop growth and meeting the crop's growth needs. Simultaneously, the water-retaining agent improves crop water use efficiency and drought resistance, provides a suitable living environment for soil microorganisms, increases nutrient absorption by crops, promotes crop nutrient and energy conversion, and promotes crop growth and development.

[0030] Wood ash is the residue left after straw combustion. Its main component is potassium carbonate, and it also contains various trace elements such as calcium, aluminum, and iron. It is a widely available, inexpensive, nutrient-rich, and highly effective farmyard manure. Because wood ash can neutralize soil acidity, and because it has many pores, a large surface area, and strong adsorption capacity, the activated calcium, aluminum, and iron ions it contains can also participate in the removal of pollutants such as ammonia and phosphorus from the soil.

[0031] Biochar is a solid, stable, and highly aromatic carbon-rich material produced by the pyrolysis and carbonization of organic matter under anaerobic or hypoxic conditions. It is characterized by high carbon content, stable chemical properties, large specific surface area, and rich pore structure. Furthermore, the oxygen-containing functional groups, organic anions, and inorganic bases in biochar can effectively condition acidified soils, and therefore it is commonly used as a soil conditioner.

[0032] The composite material was developed based on experiments on the effects of soil maturation in uranium mining areas. The composite material can shorten the maturation time of raw soil, better improve soil structure and quality, and provide a good foundation for vegetation restoration.

[0033] In a preferred embodiment, the water-retaining agent is 0.05-0.3 parts by weight, the wood ash is 0.3-0.9 parts by weight, and the biochar is 0.5-1.5 parts by weight.

[0034] In a more preferred embodiment, the water-retaining agent is 0.3 parts by weight, the wood ash is 0.3 parts by weight, and the biochar is 1 part by weight.

[0035] The present invention also provides a method for vegetation restoration in uranium mining areas. The method involves first mixing raw soil and mature soil in the uranium mining area at a weight ratio of 1:1, then using the soil conditioner described in the present invention to improve the mixed soil, laying it on the area to be restored for maturation, and then planting herbaceous plants.

[0036] The method specifically includes the following steps:

[0037] Step 1. Mix the raw soil and mature soil from the uranium mine area at a weight ratio of 1:1 to obtain a raw-mature mixed soil.

[0038] The term "composted soil" refers to the soil 0-20 cm below the surface of local cultivated land, forest land, or grassland. In this invention, the composted soil is preferably the soil 0-20 cm below the surface of local cultivated land.

[0039] Topsoil is soil that has been cultivated and matured. Topsoil is softer than raw soil, has a higher organic matter content, better physical and chemical properties, higher nutrient utilization rate, and stronger microbial activity. Adding topsoil to raw soil can significantly improve soil quality, shorten the maturation time of raw soil, and enhance the maturation effect of raw soil.

[0040] The inventors have discovered that mixing raw soil and mature soil from uranium mining areas in a 1:1 weight ratio and then modifying them with the soil conditioner provided by this invention is more conducive to soil maturation and structural performance improvement.

[0041] In a preferred embodiment, the raw soil from the uranium mine is first crushed and passed through a 70-90 mesh sieve to remove gravel. The mature soil is then crushed and passed through a 70-90 mesh sieve. The two are then mixed.

[0042] Step 2. Mix the soil conditioner, fertilizer and the raw and mature soil mixture obtained in Step 1 to obtain backfill soil.

[0043] In a preferred embodiment, based on 100 parts by weight of raw and mature mixed soil, the fertilizer is 1-5 parts by weight, preferably 2-4, more preferably 2.6; and the soil conditioner is 1-2 parts by weight, preferably 1.5-2.5, more preferably 1.6.

[0044] In this invention, the fertilizer is a compound fertilizer and / or farm fertilizer, preferably a compound fertilizer and farm fertilizer.

[0045] In this invention, the compound fertilizer refers to a chemical fertilizer that simultaneously contains nitrogen, phosphorus, and potassium nutrients. In a preferred embodiment, the N:P:K mass ratio in the compound fertilizer is (12-25):(4-15):(12-25), preferably (15-21):(6-12):(15-21), and more preferably 18:9:18.

[0046] In this invention, the farm fertilizer refers to traditional fertilizer, which is produced by collecting livestock and poultry manure and processing it into organic farm fertilizer using aerobic composting technology. This invention can use farm-made fertilizer or purchased fertilizer; there is no particular limitation in either method.

[0047] In a preferred embodiment, the weight ratio of compound fertilizer to farm fertilizer is 0.1:(1-4), preferably 0.1:(2-3), and more preferably 0.1:2.5.

[0048] Step 3. The backfill soil is laid on the area to be restored for maturation, and then grass seeds are sown to allow the grass seeds to develop and grow, thus restoring the vegetation in the uranium mining area.

[0049] The moisture content of the backfill soil should be controlled at 25-35 wt%, preferably 28-32 wt%, and more preferably around 30 wt%.

[0050] The curing process is carried out under natural conditions. The curing temperature is 15-35℃, preferably 18-35℃, and more preferably 20-32℃. The curing time is 84-126 days, preferably 108-116 days, and more preferably 110-115 days.

[0051] The preferred grass seed is rye grass seed. The sowing rate is 12-35 g / m². 2 Preferably 15-30g / m 2 More preferably 18-25 g / m 2 Mix the seeds into the soil layer of 1-3cm.

[0052] Preferably, after sowing, use non-woven fabric (approximately 15-25 g / m²) 2 Cover the soil layer and spray water to a depth of 5-10cm to penetrate the soil layer.

[0053] Preferably, watering is carried out every 3-8 days, with each irrigation amount sufficient to saturate the top 3-8 cm of soil.

[0054] Grass seeds take at least 90 days to grow after sowing. Vegetation in the uranium mining area has been restored, and soil conditions have improved.

[0055] Using the soil conditioner and vegetation restoration method provided by this invention, the improvement of soil conditions to a state suitable for plant growth is shortened by at least six months. After sowing herbaceous plants, soil conditions are significantly improved. Soil bulk density and specific gravity decrease significantly, soil acidity decreases, and available phosphorus, total nitrogen, available nitrogen, and organic matter in the soil increase significantly.

[0056] Example 1

[0057] Biochar (purity > 75%) was prepared by pyrolyzing rice husks at 600°C under a nitrogen atmosphere. The mixture of herbaceous and woody plants was burned in air to obtain plant ash.

[0058] A composite soil conditioner was prepared by mixing linear anionic polyacrylamide (Tailaibao AG101 produced by Taiwan Plastics Industry Co., Ltd.), wood ash, and biochar in a weight ratio of 3:3:10.

[0059] The raw soil from the uranium mining area is sieved through an 80-mesh sieve to remove impurities such as gravel, grass roots, and fallen debris. The topsoil (the top 0-20cm of soil in the local farmland) is sieved through an 80-mesh sieve. The sieved raw soil and topsoil are then mixed in a 1:1 weight ratio to obtain mixed soil.

[0060] Mix the mixed soil, compound fertilizer (Beijing Aojia Ecological Agriculture Co., Ltd., compound fertilizer 18-9-18, N:P:K mass ratio = 18:9:18), farm fertilizer (obtained from livestock and poultry manure compost) and compound soil conditioner in a weight ratio of 100:0.1:2.5:1.6 to obtain backfill soil E7.

[0061] Example 2

[0062] When the slope of the uranium mining area is greater than 60°, a stone revetment is constructed. When the slope is less than 60°, the waste rock on the slope is cleared, excavated, and transported to the open-pit mine ruins for centralized burial. The entire slope is divided into several sections with a height difference of less than 10m, and the sections are transitioned by a 3-5m wide water platform.

[0063] Construct intercepting ditches and diversion channels at each water platform, and build drainage ditches at the foot of the slope. The water flow from the slope flows into the intercepting ditches and then into the drainage ditches through the diversion channels, ensuring smooth drainage of the slope and guaranteeing its stability.

[0064] To ensure the stability of the slope toe, a retaining wall needs to be built at the slope toe. Since the drainage ditch is located at the slope toe, the ditch wall can also serve as the slope toe retaining wall.

[0065] The backfill soil E7 obtained in Example 1 was added to the slope and platform of the open-pit mine ruins area with a thickness of 1m. The backfill soil E7 with a thickness of 0.9m was added to the waste rock dump. The backfill soil with a thickness of 0.3m was added to the scattered waste rock piles.

[0066] Spray water onto the backfill soil, controlling the soil moisture content to around 30 wt%, allowing the backfill soil to mature for approximately 110 days. The ambient temperature should be between 15-35℃.

[0067] After the soil has matured for 30 days, sow ryegrass seeds at a rate of 20g / m². 2 Sowing should be done at a controlled rate, with seeds evenly scattered on the slope and mixed into the top 1-3 cm of soil. After mechanical sowing, the soil should be gently leveled with a fine-toothed rake, then compacted with a 10-20 catties roller to ensure full contact between the seeds and the topsoil. Finally, cover the surface with non-woven fabric (approximately 20 g / m²). 2 After covering it, spray water immediately, with the water depth reaching 5-10cm to penetrate the soil layer.

[0068] When the grass seedlings grow to 1-3cm, the non-woven fabric covering should be removed manually in a timely manner to prevent the seedlings from suffocating due to high temperatures. For the first half month after sowing, sprinkler irrigation should be carried out every 3 days, in the morning or evening, using a low-intensity sprinkler system to spray a fine mist of water to avoid washing away the seeds. Each irrigation should saturate the top 3-5cm of soil, avoiding waterlogging. As the lawn develops, the frequency of irrigation should be reduced, while the amount of water per irrigation should be increased. After 90 days of growth, the survival rate of the vegetation exceeds 90%, the vegetation cover exceeds 95%, and the assessed plant height exceeds 15cm. Compared with before treatment, the reduction in runoff and sediment both exceed 50%, demonstrating the full effectiveness of the vegetation in soil and water conservation. Photos of the vegetation cover are shown below. Figure 6 As shown.

[0069] Example 3

[0070] Backfill soil E1-E6 and backfill soil E8-E9 were prepared according to the method of obtaining backfill soil in Example 1. The only difference was the amount of polymer water-retaining agent, wood ash and biochar used, as shown in Table 1.

[0071] Table 1

[0072]

[0073] Comparative Example 1

[0074] The raw soil from the uranium mining area is sieved through an 80-mesh sieve to remove impurities such as gravel, grass roots, and fallen debris. The topsoil (the top 0-20cm of soil in the local farmland) is sieved through an 80-mesh sieve. The sieved raw soil and topsoil are then mixed in a 1:1 weight ratio to obtain the mixed soil CK.

[0075] Experimental Example

[0076] Place equal masses of backfill soil E1-E9 and mixed soil CK in soil pots. Water daily to maintain soil moisture content at approximately 60% of field capacity, with an ambient temperature of 15-35℃. After two weeks, evenly sow 20 rye seeds in each soil pot and harvest after 102 days.

[0077] (a) Measurements were taken of the backfill soil E1-backfill soil E9 and the mixed soil CK after harvesting. The results are shown in Tables 2-1 and 2-2 below.

[0078] Table 2-1 Soil physical properties before the experiment

[0079]

[0080] Table 2-2 Physical properties of soil after harvest

[0081]

[0082]

[0083] Soil specific gravity was determined using the specific gravity bottle method, while soil porosity and soil bulk density were determined using the ring cutter method.

[0084] The results show that:

[0085] (1) After planting plants in the control mixed soil CK, the soil physical properties did not change significantly compared with those before planting plants;

[0086] (2) When plants are planted after adding the soil conditioner of the present invention, the bulk density of the soil decreases by an average of 16.67% compared with the bulk density of the soil before planting.

[0087] (3) After planting and harvesting, compared with the control mixed soil CK, the bulk density and specific gravity of the mixed soil with added amendment in the embodiments of the present invention decreased by an average of 23.62% (range from 14.34% to 29.50% from E1 to E9) and 1.61% (range from 0.05% to 4.06% from E1 to E9), respectively; the porosity increased significantly, with an average increase of 27.28% (range from 16.72% to 32.45% from E1 to E9);

[0088] (4) E7 showed the best improvement effect, with the largest reduction in bulk density and the highest porosity;

[0089] (5) The soil bulk density and porosity of E1-E9 all reach the range suitable for plant growth.

[0090] (II) For the backfill soil E1-E9 and mixed soil CK after planting and harvesting, soil pH, available phosphorus content, available nitrogen content, total nitrogen content, and organic matter content were measured. The results are shown in... Figures 1-4 middle.

[0091] Among them, pH value was determined by acidity meter method, available phosphorus content was measured by concentrated sulfuric acid-perchloric acid mixed digestion-molybdenum ester colorimetric method, total nitrogen content was determined by concentrated sulfuric acid-perchloric acid mixed digestion-semi-micro Kjeldahl nitrogen determination method, and soil organic matter content was determined by potassium dichromate oxidation external heating method.

[0092] Depend on Figures 1-4It can be seen that, compared with CK, the soil pH values ​​of E1 to E9 increased by 0.84% ​​to 5.67%, respectively; available phosphorus (AP), total nitrogen (TN), available nitrogen (AN), and organic matter (OM) increased significantly by 29.34% to 97.96%, 42.78% to 63.57%, 22.34% to 61.50%, and 41.44% to 119.94%, respectively (ppH = 0.000, pTN = 0.005, pAN = 0.000, pAP = 0.000, pOM = 0.001, p < 0.05).

[0093] (III) The dry weight, plant height, and total nitrogen (TN) of ryegrass plants harvested from E1 to E9 and the mixed soil CK were measured respectively. The results are as follows: Figure 5 As shown.

[0094] pass Figure 5 It can be observed that: (1) Compared with the mixed soil CK group, in terms of plant dry weight, except for E3 which decreased by 21.68%, the E1, E2, and E4-E9 groups increased by 28.06%-266.41%, respectively, and there were significant differences among the treatment groups (E1-E9) (p=0.001, P<0.05); (2) Compared with the mixed soil CK group, in terms of plant height, except for E3, the E1, E2, and E4-E9 groups increased by 5.82%-74.0%, respectively. 6%, and there were significant differences among the treatment groups (p = 0.000, P < 0.05); (3) Compared with the mixed soil CK group, for the total nitrogen of plants, except for E3, the total nitrogen in the plants of E1, E2, E4-E9 groups increased by 19.95%-85.18%, and there were significant differences among the treatments (p = 0.000, P < 0.05). Through the change of total nitrogen of plants, we can obtain the direct effect of the material on the improvement of soil nutrients on plant growth. Overall, E7 performed the best, with plant dry weight and plant height of 84.24g and 44.77cm, respectively, which was the best among the treatment groups.

[0095] The present invention has been described in detail above with reference to specific embodiments and / or exemplary examples, as well as the accompanying drawings. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A soil conditioner comprising a water-retaining agent, wood ash, and biochar. The water-retaining agent is linear anionic polyacrylamide, the wood ash is obtained by burning a mixture of herbaceous and / or woody plants in an aerobic atmosphere, and the biochar is obtained by pyrolyzing rice husks at 500-800℃ in an anaerobic atmosphere.

2. The soil conditioner according to claim 1, characterized in that, The water-retaining agent has a particle size of 40-100 mesh. The weight ratio of water-retaining agent, wood ash, and biochar is as follows: The water-retaining agent is present in an amount of 0.05-0.3 parts by weight. The wood ash contains 0.3-0.9 parts by weight. The biochar is present in an amount of 0.5-1.5 parts by weight; preferably, The water-retaining agent is 0.3 parts by weight. The wood ash is 0.3 parts by weight. The biochar is 1 part by weight.

3. A method for vegetation restoration in a uranium mining area, characterized in that, The method first mixes the raw soil and mature soil of the uranium mining area in a 1:1 weight ratio, then adds the soil conditioner described in claim 1 or 2 to the mixture of raw soil and mature soil of the uranium mining area, and then spreads it on the area to be restored for maturation before planting herbaceous plants.

4. The method according to claim 3, characterized in that, The method specifically includes the following steps: Step 1. Mix the raw soil and mature soil from the uranium mine area at a weight ratio of 1:1 to obtain a raw-mature mixed soil; Step 2. Mix the soil conditioner, fertilizer, and the raw and mature soil mixture obtained in Step 1 to obtain backfill soil; Step 3. The backfill soil is laid on the area to be restored for maturation, and then grass seeds are sown to allow the grass seeds to develop and grow, thus restoring the vegetation in the uranium mining area.

5. The method according to claim 4, characterized in that, In step 2, Based on 100 parts by weight of raw and mature mixed soil The fertilizer weight is 1-5; The soil conditioner is 1-2 parts by weight; The fertilizer is a compound fertilizer and / or farm fertilizer, preferably a compound fertilizer and farm fertilizer, wherein the N:P:K mass ratio in the compound fertilizer is (12-25):(4-15):(12-25).

6. The method according to claim 4, characterized in that, In step 3, the curing temperature is 15-35℃, preferably 18-35℃; the curing time is 84-126 days, preferably 108-116 days.

7. The method according to claim 4, characterized in that, In step 2, The soil conditioner has a weight ratio of 1.5-2, preferably 1.

6. The fertilizer is a compound fertilizer and / or farm fertilizer, preferably a compound fertilizer and farm fertilizer, with a fertilizer weight of 1-5, preferably 2-4.

8. The method according to claim 4, characterized in that, In step 3, The moisture content of the backfill soil should be controlled at 25-35 wt%. The curing temperature is 15-35℃, preferably 18-35℃, and the curing time is 84-126 days, preferably 108-116 days.

9. The method according to claim 4, characterized in that, In step 3, the grass seed is rye grass seed, and the sowing rate is 12-35 g / m². 2 Preferably 15-30g / m 2 This allows the seeds to be mixed into the soil layer of 1-3cm.

10. The method according to claim 4, characterized in that, In step 3, the grass seeds should grow for at least 90 days after sowing.

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