Method for preparing plant-growing planting soil by utilizing industrial solid waste and microorganisms and application of plant-growing planting soil

Abstract

The invention discloses a method for preparing vegetation planting soil by utilizing industrial solid waste and microorganisms and application of the vegetation planting soil. The method comprises the following steps: mixing 80-90% of high titanium slag, 7-15% of sandy soil or phosphogypsum and 2-5% of titanium gypsum into a vegetation matrix according to specific particle size grading; inoculating a composite strain consisting of bacillus mucilaginosus and azotobacter chroococcum, fermenting at 30 DEG C for 12-18 days, and dynamically monitoring the contents of alkali-hydrolyzable nitrogen, available phosphorus and potassium and biologically extractable titanium; then, alfalfa is planted, arbuscular mycorrhizal fungi and rhizobium suspensions with the OD600 being 0.8-1.0 are regularly irrigated, and curing is conducted for 12-18 days; and irrigating and maintaining for 12-18 days by using chlorella propagation liquid every 4-6 days, and finally reserving the whole plant or harvesting to obtain the plant growing planting soil. According to the method, industrial solid waste is efficiently converted into a functional planting medium through the multi-stage biological-mineral synergistic effect, solid waste recycling and soil function reconstruction are achieved, and the method has the environment restoration and ecological reconstruction value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid waste resource utilization and ecological restoration, and particularly relates to a method for preparing plant-growing soil by utilizing industrial solid waste in cooperation with microorganisms and application thereof. BACKGROUND

[0002] With the rapid advancement of industrialization, a large amount of solid waste (such as titanium gypsum, steel slag, high-titanium slag, etc.) generated in the industrial production process has become an urgent environmental problem. The cumulative stockpiling of such industrial solid waste is huge, and its characteristics are low cementing activity and large composition fluctuation, which makes it difficult to achieve large-scale disposal through traditional building materialization paths (such as being used as cement raw materials or concrete aggregates). Long-term open-air stockpiling of these solid wastes not only occupies valuable land resources, but also may cause environmental risks such as heavy metal ion migration, soil pollution and water eutrophication due to rainwater leaching, wind diffusion, etc., seriously affecting ecological environment safety and human health.

[0003] At the same time, the demand for planting soil in the field of ecological restoration and urban greening is increasing. In some industrial cities, a large amount of planting soil is consumed every year for mine ecological restoration, municipal greening, road landscape and other projects. However, the local original soil resources are extremely scarce, and mainly rely on external purchase of red soil and humus soil to meet the demand. This external purchase mode faces multiple difficulties: high transportation cost; the resource of guest soil is becoming exhausted, and the existing supply cannot meet the demand for soil in ecological restoration. The high cost of purchasing soil and the shortage of soil resources seriously restrict the large-scale implementation of ecological restoration projects, and further affect the regional ecological safety and sustainable development.

[0004] Currently, the resource utilization of industrial solid waste mainly focuses on the building material field, such as using steel slag and slag as cement admixture or roadbed material. However, these methods have high requirements for the activity and composition stability of solid waste, and are difficult to adapt to the large-scale treatment demand of high fluctuation solid waste such as titanium gypsum and steel slag. In addition, traditional methods often ignore the ecological value of solid waste and fail to fully utilize its potential environmental functions.

[0005] It is worth noting that industrial solid waste such as titanium gypsum, steel slag and high-titanium slag has certain ecological utilization potential. For example, steel slag and slag are rich in calcium, magnesium, iron and other essential secondary elements for plants, which can be used as a mineral source of soil conditioner; titanium gypsum can adjust soil pH value and improve soil aggregate structure, which helps to alleviate the problem of soil compaction. However, single solid waste often has plant growth barriers, such as fluctuation of heavy metal content, excessive salt content or imbalance of nutrients, etc., which may inhibit plant growth or cause secondary pollution if directly used. Although there have been studies on the use of industrial solid waste for soil improvement, most of them are limited to the simple application of single solid waste, and lack of coordinated configuration, systematic modification and long-term ecological safety regulation for multi-source solid waste, resulting in that the prepared planting soil is difficult to meet the requirements of stability, safety and functionality for greening projects.

[0006] Therefore, there is an urgent need to provide a method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms. This method can solve the dual challenges of large-scale industrial solid waste disposal and soil shortage for ecological restoration by precisely grading multi-source solid waste and synergistically driving microbial communities. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms, and its application, so as to solve at least one of the above-mentioned technical problems.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for preparing vegetated planting soil using industrial solid waste and synergistic microorganisms. The method includes: S1, mixing different types of industrial solid waste evenly to obtain a vegetated substrate; the industrial solid waste includes at least one of high-titanium slag, sandy loam, phosphogypsum, and titanium gypsum; S2, adding a composite microbial strain to the vegetated substrate for fermentation and activation, the composite microbial strain being composed of Bacillus mucilaginosus and Azotobacter chrysophagus at a viable bacteria mass ratio of 6:4; S3, adding a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented vegetated substrate for maturation treatment; S4, adding Chlorella propagation solution to the maturated vegetated substrate for irrigation and maintenance to obtain vegetated planting soil.

[0009] In the first aspect, the industrial solid waste comprises, by mass percentage: 80%-90% high-titanium slag, 7%-15% sandy loam or phosphogypsum, and 2%-5% titanium gypsum; wherein the particle size of the sandy loam or phosphogypsum is 0.002-0.05 mm; the particle size of the titanium gypsum is less than 0.002 mm; and the particle size distribution (d) of the high-titanium slag is as follows: 20% of the mass is between 0.074 mm ≤ d < 0.5 mm, 30% of the mass is between 0.5 mm ≤ d < 1.0 mm, 40% of the mass is between 1.0 mm ≤ d < 2.0 mm, and 10% of the mass is between 2.0 mm ≤ d ≤ 5.0 mm.

[0010] In the first aspect, in step S2, the fermentation and curing conditions are as follows: the propagated compound strain is mixed with the vegetative substrate and fermented and cured at a constant temperature of 30°C for 12-18 days.

[0011] In the first aspect, during the fermentation and curing period, the contents of alkaline nitrogen, available potassium, available phosphorus and bioavailable titanium in the vegetative substrate are monitored every 2-4 days.

[0012] In the first aspect, in step S3, the addition of a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented plant substrate for maturation treatment specifically includes: planting alfalfa in the fermented plant substrate; after the alfalfa roots emerge, irrigating the root system with arbuscular mycorrhizal fungi and rhizobium to form a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex; and then maturation treatment for 12-18 days.

[0013] In the first aspect, the OD value of the arbuscular mycorrhizal fungal solution at a wavelength of 600 nm is 0.8-1.0, the OD value of the rhizobium solution at a wavelength of 600 nm is 0.8-1.0, the volume ratio of the arbuscular mycorrhizal fungal solution to the rhizobium solution is 1:1, and irrigation is carried out once every 5 days.

[0014] In the first aspect, in step S4, the irrigation and maintenance conditions of the Chlorella propagation solution are: irrigation once every 4-6 days, for a total of 12-18 days; the OD value of the Chlorella propagation solution at a wavelength of 680nm is 0.65-1.00.

[0015] In the first aspect, the method further includes: directly using the plants and vegetation substrate after watering and maintenance in step S4, or using the vegetation substrate after tilling the plants as planting soil; or using the vegetation substrate after harvesting or removing the plants in step S4 as planting soil.

[0016] The second aspect of the present invention provides a planting soil for vegetation, which is prepared by the method described in the first aspect of preparing planting soil using industrial solid waste and synergistic microorganisms; the performance indicators of the planting soil include: pH value of 5.5-8.5, organic matter content ≥25g / kg, total nitrogen ≥1.0g / kg, available phosphorus ≥15mg / kg, and heavy metal lead ≤300mg / kg.

[0017] The third aspect of this invention provides an application of the planting soil described in the second aspect in mine ecological restoration, municipal greening, and tailings dam remediation sites.

[0018] Beneficial effects: This invention provides a method for preparing vegetated planting soil using industrial solid waste and synergistic microorganisms. First, at least two types of industrial solid waste from slag, sandy loam, phosphogypsum, and titanium gypsum are mixed uniformly in a specific ratio to form a vegetated substrate with a porous structure and nutrient content. Second, a composite microbial strain consisting of *Bacillus mucilaginosus* and *Azotobacter chrysogenus* at a viable bacteria mass ratio of 6:4 is added to the vegetated substrate. *Bacillus mucilaginosus* dissolves and releases nutrients such as potassium and silicon from the vegetated substrate, while *Azotobacter chrysogenus* converts atmospheric nitrogen into ammonium ions to replenish the nitrogen source. This invention achieves bioactivation and nutrient enrichment of the planting substrate. Then, a symbiotic complex is constructed by pioneer nitrogen-fixing plants, arbuscular mycorrhizal fungi, and rhizobia. This further promotes mineral weathering, nitrogen transformation, organic matter accumulation, and aggregate formation in the rhizosphere microdomain, completing the ecological maturation of the planting substrate. Finally, a Chlorella propagation solution is added for irrigation and maintenance. The polysaccharides, amino acids, and growth factors secreted by Chlorella enhance the substrate's water and fertilizer retention capacity, regulate the microbial community structure, and reduce the salinity of industrial solid waste. Ultimately, a planting soil with excellent physicochemical properties, high biological activity, and suitable for long-term plant growth is obtained. This invention efficiently transforms industrial solid waste into a functional planting medium through multi-level biological-mineral synergistic effects, realizing the resource utilization of solid waste and the reconstruction of soil function, and possessing value for environmental remediation and ecological reconstruction.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms, as described in this invention. Detailed Implementation

[0022] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0023] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0025] Please see Figure 1 This invention provides a method for preparing vegetated planting soil using industrial solid waste and synergistic microorganisms. The method includes: S1, mixing different types of industrial solid waste evenly to obtain a vegetated substrate; the industrial solid waste includes at least one of high-titanium slag, sandy loam, phosphogypsum, and titanium gypsum; S2, adding a compound microbial strain to the vegetated substrate for fermentation and activation, the compound microbial strain being composed of Bacillus mucilaginosus and Azotobacter chrysophytes at a viable bacteria mass ratio of 6:4; S3, adding a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented vegetated substrate for maturation treatment; S4, adding Chlorella propagation solution to the maturated vegetated substrate for irrigation and maintenance to obtain vegetated planting soil.

[0026] Specifically, this invention provides a method for preparing vegetated planting soil using industrial solid waste and synergistic microorganisms. First, at least two types of industrial solid waste from high-titanium slag, sandy loam, phosphogypsum, and titanium gypsum are mixed evenly in a specific ratio to form a vegetated substrate with a porous structure and nutrient content. Second, a composite microbial strain consisting of *Bacillus mucilaginosus* and *Azotobacter chrysogenum* at a viable bacteria mass ratio of 6:4 is added to the vegetated substrate. *Bacillus mucilaginosus* dissolves and releases nutrients such as potassium and silicon from the vegetated substrate, while *Azotobacter chrysogenum* converts atmospheric nitrogen into ammonium ions. Ions and supplemental nitrogen sources work together to achieve biological activation and nutrient enrichment of the planting substrate. Then, a symbiotic complex constructed by pioneer nitrogen-fixing plants, arbuscular mycorrhizal fungi, and rhizobia is introduced to further promote mineral weathering, organic matter accumulation, and aggregate structure formation in the rhizosphere microdomain, thus completing the ecological maturation of the planting substrate. Finally, Chlorella propagation solution is added for irrigation and maintenance, utilizing the polysaccharides, amino acids, and growth factors secreted by Chlorella to enhance the substrate's water and fertilizer retention capacity and regulate the microbial community structure, ultimately obtaining a planting soil with excellent physical and chemical properties, high biological activity, and suitable for long-term plant growth. It is worth noting that this invention uses high-titanium slag and titanium gypsum, which can activate the growth-promoting effect of the trace element titanium on the pioneer plant alfalfa, thereby accelerating the transformation of industrial solid waste from a primary ecology to a mature and stable microbial ecology. 1) Titanium can increase the activity of nitrogenase in rhizobia and may promote the formation and growth of root nodules, thus directly enhancing the ability to convert nitrogen into ammonia; 2) Titanium can increase the chlorophyll content in alfalfa leaves and improve the rate of photosynthesis, providing more carbohydrates (energy) for the energy-consuming nitrogen fixation process and plant growth; 3) Titanium can promote the absorption of essential mineral elements such as nitrogen, phosphorus, and potassium by alfalfa roots. Phosphorus and potassium are crucial for the formation of root nodules and the activity of nitrogenase. This invention, through multi-level biological-mineral synergy, activates the matrix's original nutrients and natural nutrients (carbon and nitrogen accumulation), efficiently transforming industrial solid waste into a functional planting medium, realizing the resource utilization of solid waste and the reconstruction of soil function, and providing a new strategy for the green, low-cost, and sustainable ecological utilization of industrial solid waste. It has environmental remediation and ecological reconstruction value.

[0027] In some possible embodiments, the industrial solid waste comprises, by mass percentage: 80%-90% high-titanium slag, 7%-15% sandy loam or phosphogypsum, and 2%-5% titanium gypsum; wherein the particle size of the sandy loam or phosphogypsum is 0.002-0.05 mm; the particle size of the titanium gypsum is less than 0.002 mm; the particle size distribution (d) of the high-titanium slag is as follows: 20% by mass for particles between 0.074 mm and d < 0.5 mm, 30% by mass for particles between 0.5 mm and d < 1.0 mm, 40% by mass for particles between 1.0 mm and d < 2.0 mm, and 10% by mass for particles between 2.0 mm and d ≤ 5.0 mm.

[0028] In this application, the vegetation substrate is scientifically formulated from industrial solid waste with a specific ratio and particle size distribution. Its composition, by mass percentage, is: 80%-90% high-titanium slag, 7%-15% sandy loam or phosphogypsum, and 2%-5% titanium gypsum. This formulation design is based on a multi-scale mineral synergistic mechanism: high-titanium slag serves as the main framework material, with a gradient particle size distribution (0.074-0.5 mm accounting for 20%, 0.5-1.0 mm for 30%, 1.0-2.0 mm for 40%, and 2.0-5.0 mm for 10%). This ensures both a good pore structure and excellent air and water permeability of the vegetation substrate, and, due to its rich content of active silica, aluminum, and calcium components, it can slowly release Ca under the action of microorganisms. 2 + SiO3 2- Al 3+ Plasma promotes agglomeration and pH buffering; sandy loam or phosphogypsum (particle size 0.002-0.05 mm) serves as a medium-fine particle filler phase, not only regulating the matrix bulk density and water retention, but also providing plant-available phosphorus, calcium, and trace sulfur elements, although the dosage must be controlled to avoid potential risks from fluorine or heavy metals; ultrafine titanium gypsum (particle size <0.002 mm) exerts a nanoscale mineral effect, its high specific surface area enhancing the adsorption and fixation capacity of nutrient molecules, and participating in sulfate reduction and metal passivation processes under the action of composite microbial communities. Through the complementarity of particle size distribution and chemical composition, these three components construct a porous mineral matrix that combines structural stability, slow nutrient release, and bioavailability, laying a physicochemical foundation for subsequent microbial activation, mycorrhizal symbiosis, and algal regulation, thereby efficiently driving the ecological transformation of industrial solid waste into functional planting soil.

[0029] In some possible embodiments, in step S2, the fermentation and curing conditions are as follows: the propagated compound microorganism is mixed with the vegetative substrate and fermented and cured at a constant temperature of 30°C for 12-18 days.

[0030] Specifically, in step S2, the propagated composite bacterial strain (composed of *Bacillus mucilaginosus* and *Azotobacter chrysogenus* at a live cell mass ratio of 6:4) is uniformly inoculated into the vegetative substrate and fermented at a constant temperature of 30°C for 12-18 days. This temperature condition precisely matches the optimal growth and metabolic activity window of the two types of functional bacteria: *Bacillus mucilaginosus* efficiently secretes organic acids (such as citric acid and oxalic acid) and extracellular polysaccharides at this temperature, accelerating the weathering and dissolution of aluminosilicate minerals in high-titanium slag and insoluble calcium, phosphorus, and potassium minerals in titanium gypsum and phosphogypsum through acid dissolution and complexation, releasing nutrients available to plants; simultaneously, the polysaccharides it produces promote the formation of substrate micro-aggregates, improving structural stability. Meanwhile, *Azotobacter chrysogenus* actively performs aerobic nitrogen fixation under the same temperature-controlled environment, converting atmospheric N2 into NH4+. 4+Organic nitrogen compounds significantly increase the nitrogen level of the vegetative substrate. Two types of microbial communities form a synergistic interaction in both space and function—the minerals released by *Bacillus mucilaginosus* provide trace elements for *Azotobacter chrysogenum* to maintain nitrogenase activity, while the nitrogen fixed by the latter in turn nourishes the former's growth and metabolism. After 12-18 days of continuous biological action, not only are the potential nutrients in the substrate activated and transformed, but a microbial-mineral complex system with preliminary biological activity and nutrient slow-release capacity is also constructed, laying the nutritional and ecological foundation for the subsequent introduction of pioneering nitrogen-fixing plant-mycorrhizal symbiotic systems.

[0031] In some possible embodiments, during the fermentation and curing period, the contents of available nitrogen, available potassium, available phosphorus, and bioavailable titanium in the vegetative substrate are monitored every 2-4 days.

[0032] In this application, during the fermentation and curing of the plant substrate, the contents of alkaline nitrogen, available potassium, available phosphorus, and bioavailable titanium in the plant substrate are dynamically monitored every 2-4 days to precisely regulate the microbial-mineral reaction process and assess nutrient activation efficiency. This monitoring strategy is based on the following reaction mechanism: *Azotobacter chrysogenum* continuously fixes atmospheric nitrogen and converts it into ammonia nitrogen, which, under alkaline hydrolysis conditions, manifests as a steady increase in alkaline nitrogen content, reflecting biological nitrogen fixation efficiency; *Bacillus cannabinoids* gradually dissolves and releases structural potassium and phosphogypsum from high-titanium slag, as well as bound phosphorus and potassium from titanium gypsum, through the secretion of organic acids and chelating agents, resulting in a phased increase in available potassium and available phosphorus concentrations, characterizing mineral weathering and nutrient release kinetics; simultaneously, the originally inert titanium components in titanium gypsum are partially converted into bioavailable forms (such as Ti) under the action of the acidic microenvironment and microbial metabolites. 4+ -Organic complexes), the changes in their content not only indicate the potential bioavailability of titanium, but also indirectly reflect the degree of acidification and the intensity of microbial activity in the system. By regularly monitoring the above indicators, the synergistic transformation capacity of the complex microbial community for multiple elements in industrial solid waste can be grasped in real time, the fermentation cycle can be optimized, and it can be ensured that the substrate has a balanced supply of readily available nutrients and low ecological risk before entering the maturation stage, thereby ensuring the stable construction of the subsequent vegetation system.

[0033] In some possible embodiments, in step S3, the addition of a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented plant substrate for maturation treatment specifically includes: planting alfalfa in the fermented plant substrate; after the alfalfa roots emerge, irrigating the root system with arbuscular mycorrhizal fungi to form a pioneer nitrogen-fixing plant-arbuscular mycorrhizal complex; and then maturation treatment for 12-18 days.

[0034] In some possible embodiments, the arbuscular mycorrhizal fungal solution has an OD value of 0.8-1.0 at a wavelength of 600 nm and is applied every 5 days.

[0035] Specifically, the fermented and activated plant substrate is used to plant alfalfa, and simultaneously irrigated with a spore suspension containing arbuscular mycorrhizal fungi and a rhizobium inoculum solution to construct a symbiotic complex of "pioneer nitrogen-fixing plant-arbuscular mycorrhizal fungi-rhizobium". This complex is then subjected to an ecological maturation treatment for 12-18 days. This process relies on multiple biogeochemical mechanisms driven by plant-microbe synergy: alfalfa, as a typical pioneer leguminous plant, has symbiotic rhizobia in its root nodules that efficiently fix atmospheric nitrogen, continuously supplying organic nitrogen to the substrate and significantly increasing the system's nitrogen pool; at the same time, its roots secrete large amounts of organic acids, sugars, and signaling molecules, which not only improve the micro-domain pH environment but also promote the further dissolution and transformation of phosphorus, calcium, sulfur, and trace metal elements in residual mineral phases (such as incompletely activated phosphogypsum and titanium gypsum). Meanwhile, arbuscular mycorrhizal fungi extend beyond the rhizosphere through their hyphal networks, significantly expanding the nutrient absorption radius, especially enhancing their ability to acquire immobile phosphorus and potassium. They also activate inert phosphorus pools in the substrate by secreting phosphatases and organic acids. Furthermore, the vesicles and arbuscular structures formed by arbuscular mycorrhizal fungi efficiently transport absorbed nutrients to the plant, while the plant reciprocates with photosynthetic products, creating a mutually beneficial symbiotic cycle. More importantly, the glomerulimycin-associated soil protein (GRSP) secreted by the hyphae has a strong cementing effect, effectively promoting the formation of microaggregates and significantly improving the substrate's structural stability, water retention, and aeration. After 12-18 days of synergistic maturation, the planting substrate evolves from a simple mineral-microorganism system into a three-in-one active medium of "plant-bacteria-fungi" with complete rhizosphere ecological functions, laying a solid biological foundation for subsequent Chlorella regulation and the final functional improvement of the planting soil.

[0036] In some possible embodiments, in step S4, the irrigation and maintenance conditions of the Chlorella propagation solution are: irrigation once every 4-6 days, for a total of 12-18 days.

[0037] In this application, Chlorella propagation solution is used to periodically irrigate and maintain the matured planting substrate, specifically irrigating every 4-6 days for 12-18 consecutive days. This irrigation strategy aims to further optimize the biological activity and ecological function of the planting soil through the continuous input of microalgal metabolites. Chlorella propagation solution is rich in proteins, polysaccharides, amino acids, plant growth hormones, and various vitamins. Regular application can significantly increase the organic matter content of the substrate and improve its water and fertilizer retention capacity. Among these, extracellular polysaccharides have strong adhesive and cementing effects, promoting the stability of micro-aggregates and enhancing soil structure. Simultaneously, algal-derived organic nitrogen and slow-release nutrients can be gradually utilized by indigenous microorganisms and plant roots, forming a sustainable nutrient supply cycle. Furthermore, the active substances secreted by Chlorella can stimulate the proliferation of beneficial rhizosphere microorganisms, regulate the microecological balance, and temporarily increase the redox potential of the root zone through photosynthetic oxygen release, alleviating potential reducing toxicity (such as Fe). 2+ Mn2+ (Excessive irrigation). Periodic irrigation every 12-18 days ensures the effective accumulation of algal metabolites while avoiding poor aeration due to excessive moisture. This allows the substrate to complete its final ecological acclimatization while establishing a stable micro-ecosystem of algae-bacteria-plant synergy. The resulting planting soil not only possesses excellent physical and chemical properties but also exhibits sustained biological vitality and plant growth-promoting ability, making it suitable for ecological restoration and vegetation reconstruction of degraded land or engineering damage.

[0038] In some possible embodiments, the method further includes: directly using the plants and vegetation substrate after watering and maintenance in step S4, or using the planted plants after tilling into the vegetation substrate as planting soil; or using the vegetation substrate after harvesting or removing the plants in step S4 as planting soil.

[0039] In this application, after completing step S4 of periodic irrigation and maintenance with the Chlorella propagation solution (12-18 days), the final method of forming the planting soil can be flexibly selected according to the actual application scenario: First, the pioneer plants (such as alfalfa) and their roots and the entire planting substrate are retained as the finished planting soil and applied directly; Second, after the maintenance is completed, the above-ground plants are harvested or removed, and only the planting substrate rich in root residues, microbial communities and algal-bacterial metabolites is used as the planting soil. Both models offer significant ecological advantages: the former is suitable for slope restoration or rapid greening projects requiring immediate vegetation cover, where plant roots are deeply embedded in the substrate, forming a "living anchor" structure that greatly enhances erosion resistance while continuously performing photosynthetic carbon fixation and nutrient cycling; the latter is more suitable for seedling cultivation or soil improvement scenarios where other target plants are subsequently transplanted, where residual root organic matter and rhizosphere deposits (such as glomerulonephrine, polysaccharides, and humic precursors) can be rapidly degraded by microorganisms into stable humic components, further enhancing the substrate's cation exchange capacity, buffering capacity, and bioavailable nutrient pool. Regardless of the method used, the system formed after the S4 stage integrates the industrial solid waste mineral framework, the synergistic functions of nitrogen fixation, phosphorus solubilization, mycorrhizae, and microalgae, and the initially formed soil aggregate structure, possessing good physical stability, chemical fertility, and biological activity, truly achieving a closed-loop transformation from "solid waste" to "functional ecological planting medium."

[0040] Based on a general inventive concept, the second aspect of this invention provides a planted soil, which is prepared by the method described in the first aspect of using industrial solid waste and synergistic microorganisms to prepare planted soil; the performance indicators of the planted soil include: pH value of 5.5-8.5, organic matter content ≥25g / kg, total nitrogen ≥1.0g / kg, available phosphorus ≥15mg / kg, and heavy metal lead ≤300mg / kg.

[0041] Specifically, the vegetative planting soil system provided by the present invention is prepared through the aforementioned multi-level transformation process of industrial solid waste synergistic with microorganisms (including precise solid waste ratio, compound microbial community activation, pioneer plant-arbuscular mycorrhizal-rhizobium symbiotic maturation and Chlorella regulation and maintenance), and its physicochemical and ecological properties meet the practical standards for planting media used in agriculture or ecological restoration. The pH value of the prepared planting soil is stable within the range of 5.5-8.5, thanks to the dynamic balance between the alkaline buffering capacity of high-titanium slag and the acid production of microbial metabolism. This avoids the strong acid / alkali stress that may be caused by phosphogypsum or titanium gypsum, and provides a suitable growth environment for plants and microorganisms. The organic matter content is ≥25 g / kg, mainly from alfalfa root residues, mycelium, globulin-associated protein (GRSP), and polysaccharides and proteins secreted by Chlorella, which significantly improves the water retention, aeration and cation exchange capacity of the substrate. The total nitrogen content is ≥1.0 g / kg, which comes from the biological nitrogen fixation of Azotobacter glomerulosa, the symbiotic nitrogen fixation of rhizobia-pioneer plants, and the enrichment and cycling of nitrogen by algae-bacteria systems, ensuring a long-term nitrogen supply. The available phosphorus is ≥15 mg / kg, which is attributed to the synergistic release mechanism of phosphorus solubilization by Bacillus cannabinoids, activation of insoluble phosphorus by arbuscular mycorrhizal mycelium, and slow-release phosphorus from phosphogypsum. Crucially, despite the presence of various industrial byproducts in the raw materials, the lead (Pb) content is effectively controlled within the safe threshold of ≤300 mg / kg through multiple processes including mineral fixation, microbial passivation, and organic complexation, meeting the standard of "Greening Planting Soil" (CJ / T 340-2016). In summary, the planting soil prepared by this invention not only achieves high-value ecological utilization of industrial solid waste but also possesses comprehensive advantages such as balanced fertility, good structure, and environmental safety, making it widely applicable in ecological engineering scenarios such as mine reclamation, slope greening, and degraded land improvement.

[0042] Based on a general inventive concept, the third aspect of this invention provides an application of the planting soil described in the second aspect in mine ecological restoration, municipal greening, and tailings dam remediation sites.

[0043] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0044] The compound bacterial strain consisted of *Bacillus mucilaginosus* and *Azotobacter chrysogenus* at a viable cell ratio of 6:4. The expansion culture medium consisted of mannitol, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, sodium chloride, calcium sulfate dihydrate, calcium carbonate, agar, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, magnesium sulfate heptahydrate, calcium sulfate dihydrate, ferric chloride, sodium molybdate, yeast extract, mannitol, and agar. The aeration rate was 1.0 vvm, and the incubation time was 48 hours. *Bacillus mucilaginosus* was selected from the *Gray Algae* biological / microbial resource identification and preservation platform HZB224030, and *Azotobacter chrysogenus* was selected from the *Gray Algae* biological / microbial resource identification and preservation platform HZB221966.

[0045] Chlorella: FACHB-10 purchased from the Freshwater Algae Seed Bank of the Chinese Academy of Sciences; the purchased Chlorella was cultured to obtain Chlorella propagation solution, with an OD value of 0.65-1.00 at a wavelength of 680nm.

[0046] Example 1 This embodiment provides a method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms, which specifically includes the following steps: (1) By mass percentage, 80% high-titanium slag, 15% sandy loam and 5% titanium gypsum were mixed to prepare a vegetation substrate. The particle size distribution of the high-titanium slag was 20% for 0.074-0.5 mm, 30% for 0.5-1.0 mm, 40% for 1.0-2.0 mm and 10% for 2.0-5.0 mm; the particle size of the sandy loam was 0.002-0.05 mm; and the particle size of the titanium gypsum was less than 0.002 mm. (2) Add a compound microbial strain (Synbio-M) to the plant substrate for fermentation and activation. The compound microbial strain consists of Bacillus colloidis and Azotobacter chrysogenum at a live cell mass ratio of 6:4. The expansion liquid culture medium includes mannitol, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, sodium chloride, calcium sulfate dihydrate, calcium carbonate, agar, ferric chloride, sodium molybdate, and yeast extract. The aeration rate is 1.0 vvm. After culturing for 48 hours, the expanded microbial agent is mixed with the plant substrate and fermented and maintained at a constant temperature of 30℃ for 15 days. During the fermentation period, the alkaline nitrogen, available potassium, available phosphorus, and bioavailable titanium content of the plant substrate are monitored every 3 days. (3) Add a pioneer nitrogen-fixing plant (alfalfa)-arbuscular mycorrhizal complex (Synbio-P) to the fermented plant substrate and allow it to mature for 15 days; (4) Add Synbio-A propagation solution to the matured vegetative substrate and irrigate and maintain it for 15 days, irrigating once every 5 days to obtain vegetative planting soil; Performance testing of the planting soil revealed the following results: pH value 6.8, organic matter content 32 g / kg, total nitrogen 1.2 g / kg, available phosphorus 18 mg / kg, lead content 120 mg / kg, and specific gravity 1.3 g / cm³. 3 0.8 g / cm³ 3 The soil has a porosity of 42% and a field water holding capacity of 28%, all of which meet the standards of "Greening Planting Soil" (CJ / T 340-2016). The planting soil prepared in this embodiment was used in an ecological restoration project of a mine in Panzhihua, where sisal and *Prunus armeniaca* were planted. The plant survival rate reached 96%, and the vegetation coverage increased by 23% compared to traditional topsoil.

[0047] In addition, the fermented plant substrate was tested before step (3), and its water-soluble titanium content was 4.83 mg / kg and its available nitrogen content was 0.1 mg / kg; the plant substrate after maturation in step (3) was tested, and its water-soluble titanium content was 5.50 mg / kg and its available nitrogen content was 4.9 mg / kg.

[0048] Furthermore, the sandy loam with a mass percentage of 15% in Example 1 was replaced with phosphogypsum with a mass percentage of 15%. The water-soluble titanium content in the fermented vegetation substrate was 4.58 mg / kg, and the available nitrogen content was 0.4 mg / kg. The water-soluble titanium content in the matured vegetation substrate was 5.21 mg / kg, and the available nitrogen content was 18.48 mg / kg.

[0049] Example 2 This embodiment provides a method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms, which specifically includes the following steps: (1) By mass percentage, 90% high-titanium slag, 7.5% sandy loam and 2.5% titanium gypsum were mixed to prepare a vegetation substrate. The particle size distribution of the high-titanium slag was 0.074-0.5 mm accounting for 20%, 0.5-1.0 mm accounting for 30%, 1.0-2.0 mm accounting for 40%, and 2.0-5.0 mm accounting for 10%; the particle size of the sandy loam was 0.002-0.05 mm; and the particle size of the titanium gypsum was less than 0.002 mm. (2) Add a compound microbial strain (Synbio-M) to the plant substrate for fermentation and activation. The compound microbial strain consists of Bacillus colloidis and Azotobacter chrysogenum at a live cell mass ratio of 6:4. The expansion liquid culture medium includes mannitol, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, sodium chloride, calcium sulfate dihydrate, calcium carbonate, agar, ferric chloride, sodium molybdate, and yeast extract. The aeration rate is 1.0 vvm. After culturing for 48 hours, the expanded microbial agent is mixed with the plant substrate and fermented and maintained at a constant temperature of 30℃ for 15 days. During the fermentation period, the alkaline nitrogen, available potassium, available phosphorus, and bioavailable titanium content of the plant substrate are monitored every 3 days. (3) Add the pioneer nitrogen-fixing plant (alfalfa)-arbuscular mycorrhizal complex (Synbio-P) to the fermented plant substrate and mature it for 15 days. Harvest the alfalfa after maturity. (4) Add Synbio-A propagation solution to the matured vegetative substrate and irrigate and maintain it for 15 days, irrigating once every 5 days to obtain vegetative planting soil; Performance testing of the planting soil revealed the following results: pH value 7.2, organic matter content 28 g / kg, total nitrogen 1.1 g / kg, available phosphorus 16 mg / kg, lead content 110 mg / kg, and specific gravity 1.4 g / cm³. 3 0.9 g / cm³ 3 The porosity is 39%, and the field water holding capacity is 26%, all of which meet the standards of "Greening Planting Soil" (CJ / T 340-2016). The planting soil prepared in this embodiment was used in a municipal greening project in Panzhihua, where native plants were planted. The survival rate of the plants reached 95%, and their growth was excellent.

[0050] In addition, the fermented plant substrate was tested before step (3), and its water-soluble titanium content was 1.64 mg / kg and its available nitrogen content was 0.45 mg / kg; the plant substrate after maturation in step (3) was tested, and its water-soluble titanium content was 4.65 mg / kg and its available nitrogen content was 6.3 mg / kg.

[0051] Furthermore, the sandy loam with a mass percentage of 7.5% in Example 2 was replaced with phosphogypsum with a mass percentage of 7.5%. The water-soluble titanium content in the fermented plant substrate was 3.18 mg / kg, and the available nitrogen content was 0.5 mg / kg. The water-soluble titanium content in the matured plant substrate was 3.80 mg / kg, and the available nitrogen content was 3.5 mg / kg.

[0052] Example 3 In this embodiment, the vegetation substrate is prepared by mixing 90% high-titanium slag and 10% sandy loam by mass percentage, and the remaining steps are the same as in Example 1.

[0053] Test results showed that the pH of the planting soil was 8.5, the organic matter content was 13 g / kg, and the cation exchange capacity was 76.69 cmol. ＋ The concentration of total nitrogen was 0.5 g / kg, available phosphorus was 8 mg / kg, lead content was 0.18 mg / kg, and specific gravity was 3.17 g / cm³. 3 The bulk density is 1.31 g / cm³. 3 The porosity is 50.82%, the field water holding capacity is 203.55 g / kg, and the survival rate of plants after planting sisal and mulberry is 85%.

[0054] In addition, the fermented plant substrate was tested before step (3), and its water-soluble titanium content was 1.46 mg / kg and its available nitrogen content was 0.2 mg / kg; the plant substrate after maturation in step (3) was tested, and its water-soluble titanium content was 7.12 mg / kg and its available nitrogen content was 3.5 mg / kg.

[0055] Example 4 In this embodiment, 90% high-titanium slag and 10% phosphogypsum were mixed by mass percentage to prepare the vegetation substrate, and the remaining steps were the same as in Example 1.

[0056] Test results showed that the pH of the planting soil was 6.51, the organic matter content was 28 g / kg, and the cation exchange capacity was 78.487 cmol. ＋ The total nitrogen content is 0.6 g / kg, the available phosphorus content is 6 mg / kg, the lead content is 0.06 mg / kg, and the specific gravity is 3.1 g / cm³. 3 The bulk density is 1.34 g / cm³. 3 The porosity is 51.23%, the field water holding capacity is 220.8 g / kg, and the survival rate of plants after planting sisal and mulberry is 80%.

[0057] In addition, the fermented plant substrate was tested before step (3), and its water-soluble titanium content was 4.88 mg / kg and its available nitrogen content was 0.1 mg / kg; the plant substrate after maturation in step (3) was tested, and its water-soluble titanium content was 5.07 mg / kg and its available nitrogen content was 4.9 mg / kg.

[0058] Example 5 In this embodiment, 100% high-titanium slag was directly selected to prepare the vegetation substrate, and the remaining steps were the same as in Example 1.

[0059] The test results showed that the pH of the planting soil was 7.07, the organic matter content was 14.25 g / kg, and the cation exchange capacity was 77.359 cmol. ＋The total nitrogen content was 0.65 g / kg, the available phosphorus content was 90.98 mg / kg, the lead content was 1.28 mg / kg, the specific gravity was 3 g / cm3, the bulk density was 1.35 g / cm3, the porosity was 60.1%, the field water holding capacity was 200.8 g / kg, and the survival rate of plants after planting sisal and mulberry was 50%.

[0060] In addition, the fermented plant substrate was tested before step (3), and its water-soluble titanium content was 1.36 mg / kg and its available nitrogen content was 0.6 mg / kg; the plant substrate after maturation in step (3) was tested, and its water-soluble titanium content was 4.65 mg / kg and its available nitrogen content was 3.5 mg / kg.

[0061] Comparative Example 1 In this comparative example, the vegetative substrate was not fermented and activated using a compound microbial strain (Synbio-M), and the remaining steps were the same as in Example 1.

[0062] The test results showed that the organic matter content of the planting soil was 18g / kg, the total nitrogen was 0.7g / kg, and the available phosphorus was 8mg / kg, which did not meet the standard of "Greening Planting Soil" (CJ / T 340-2016). At the same time, the survival rate of sisal and mulberry trees planted with the planting soil prepared using this comparative ratio was only 72%.

[0063] Comparative Example 2 In this comparative example, the matured vegetative substrate was not irrigated and maintained with Synbio-A propagation solution; the remaining steps were the same as in Example 1.

[0064] Test results showed that the pH value of the planting soil was 8.8, which exceeded the range of 5.5-8.5 specified in "Greening Planting Soil" (CJ / T 340-2016). The cation exchange capacity was low, resulting in insufficient nutrient absorption during plant growth, and the survival rate was 81%.

[0065] In summary, compared with the prior art, the present invention has the following advantages: (1) This invention uses a combination technology of precise combination of multi-source solid waste and synergistic activation of microorganisms to convert industrial solid waste that is difficult to dispose of into vegetative planting soil. The solid waste utilization rate is high, which effectively solves the environmental problem of long-term stockpiling of industrial solid waste and reduces the cost of solid waste disposal.

[0066] (2) The planting soil prepared by the present invention has excellent performance, and its physical structure and chemical properties meet the requirements of greening and planting.

[0067] (3) The present invention can not only alleviate the pressure of depletion of native soil resources by planting in situ, but also reduce the cost of purchasing soil in ecological restoration projects.

[0068] (4) The present invention forms a closed-loop model of “solid waste disposal-soil production-ecological reconstruction”, which can build a treatment line on the spot of the solid waste dump, and the produced planting soil is directly supplied to the mining area or surrounding ecological restoration projects, realizing “waste soil exchange”, promoting the transformation of the solid waste dump from a pollution source to a resource base and ecological barrier, with significant economic, social and environmental benefits.

[0069] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0070] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0071] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms, characterized in that, The method includes: S1. Mix different types of industrial solid waste evenly to obtain a vegetation substrate; the industrial solid waste includes at least one of high-titanium slag, titanium gypsum, sandy loam, and phosphogypsum. S2. Add a compound microbial strain to the plant substrate for fermentation and activation. The compound microbial strain is composed of Bacillus mucilaginosus and Azotobacter chrysophagus at a live bacteria mass ratio of 6:

4. S3. Add a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented vegetation substrate for maturation treatment. S4. Add Chlorella propagation solution to the matured vegetative substrate for irrigation and maintenance to obtain vegetative planting soil.

2. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 1, characterized in that, The industrial solid waste, by mass percentage, includes: 80%-90% high-titanium slag, 7%-15% sandy loam or phosphogypsum, and 2%-5% titanium gypsum; The particle size of the sandy soil or phosphogypsum is 0.002-0.05 mm; the particle size of the titanium gypsum is less than 0.002 mm; the particle size distribution (d) of the high-titanium slag is as follows: 20% of the mass is between 0.074 mm ≤ d < 0.5 mm, 30% of the mass is between 0.5 mm ≤ d < 1.0 mm, 40% of the mass is between 1.0 mm ≤ d < 2.0 mm, and 10% of the mass is between 2.0 mm ≤ d ≤ 5.0 mm.

3. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 1, characterized in that, In step S2, the fermentation and curing conditions are as follows: the propagated compound microbial strain is mixed with the vegetative substrate and fermented and cured at a constant temperature of 30°C for 12-18 days.

4. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 3, characterized in that, During the fermentation and curing period, the contents of alkaline nitrogen, available potassium, available phosphorus, and bioavailable titanium in the vegetative substrate were monitored every 2-4 days.

5. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 1, characterized in that, In step S3, the addition of a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex to the fermented plant substrate for maturation treatment specifically includes: planting alfalfa in the fermented plant substrate; after the alfalfa roots emerge, irrigating the root system with arbuscular mycorrhizal fungi and rhizobium to form a pioneer nitrogen-fixing plant-arbuscular mycorrhizal-rhizobium complex; and then maturation treatment for 12-18 days.

6. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 5, characterized in that, The OD value of the arbuscular mycorrhizal fungal solution at a wavelength of 600 nm is 0.8-1.0, the OD value of the rhizobium solution at a wavelength of 600 nm is 0.8-1.0, the volume ratio of the arbuscular mycorrhizal fungal solution to the rhizobium solution is 1:1, and irrigation is performed once every 5 days.

7. The method for preparing vegetated planting soil using industrial solid waste and synergistic microorganisms according to claim 1, characterized in that, In step S4, the irrigation and maintenance conditions of the Chlorella propagation solution are as follows: irrigation once every 4-6 days, for a total of 12-18 days; the OD value of the Chlorella propagation solution at a wavelength of 680nm is 0.65-1.

00.

8. The method for preparing vegetative planting soil using industrial solid waste and synergistic microorganisms according to claim 1, characterized in that, The method further includes: The plants and vegetation substrate after irrigation and maintenance in step S4, or the plants after tilling and planting, can be used as planting soil. or, After watering and maintenance in step S4, the plant substrate is harvested or removed to serve as planting soil.

9. A type of growing soil, characterized in that, The planting soil is prepared by the method of preparing planting soil using industrial solid waste and synergistic microorganisms as described in any one of claims 1-7; the performance indicators of the planting soil include: pH value of 5.5-8.5, organic matter content ≥25g / kg, total nitrogen ≥1.0g / kg, available phosphorus ≥15mg / kg, and heavy metal lead ≤300mg / kg.

10. The application of the planting soil as described in claim 9 in mine ecological restoration, municipal greening and tailings dam remediation sites.

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