Flower nutrient soil based on lithium feldspar slag and preparation method thereof

Abstract

The application discloses a kind of flower nutrient soil based on spodumene slag and a preparation method thereof.The flower nutrient soil includes the following components by mass fraction: 70-90 parts of spodumene slag;3-10 parts of pine needles;5-25 parts of biomass fermentation residue;0.5-1 part of microbial inoculum.The application takes the lithium extraction by-product spodumene slag as the main raw material, fully utilizes its natural advantage of rich calcium and silicon available to flowers, through specific compounding with functional biomass materials and microbial inoculum, and through flower synergistic cultivation, converts the spodumene slag into high-end flower nutrient soil with high nutrients, slightly acidic and calcium-silicon synergistic supply.Each nutrient value of the nutrient soil meets the standard, especially suitable for Clivia, orchid, lily and other calcium-loving high-end flowers, with the advantages of low raw material cost, nutrient slow release, loose and stable structure, etc.

Description

Technical Field

[0001] This invention relates to a flower nutrient soil based on spodumene slag, and also to its preparation method, belonging to the technical field of solid waste resource utilization and horticultural substrate preparation. Background Technology

[0002] With the explosive growth of the new energy vehicle and energy storage industries, the demand for lithium resources has surged. Spodumene is one of the core ores for extracting lithium salts, and its acid or alkaline lithium extraction process generates a large amount of spodumene slag. Statistics show that approximately 8-12 tons of spodumene slag are emitted for every ton of lithium carbonate produced. Currently, my country's annual spodumene slag emissions have reached millions of tons, with a massive accumulated stockpile. This slag is mostly stored in the open, not only occupying valuable land resources, but also its fine particles are easily eroded by wind, forming dust, and may release heavy metal ions and salts under rainwater leaching, posing a potential threat to the surrounding soil and groundwater environment. Therefore, how to achieve large-scale, high-value-added resource utilization of spodumene slag has become a key bottleneck restricting the green and sustainable development of the lithium battery industry.

[0003] Existing research on the resource utilization of spodumene slag mainly focuses on low-value-added applications, such as its use as a cement admixture, concrete additive, and roadbed subbase material. These utilization methods, on the one hand, impose stringent requirements on the chemical composition and physical stability of the waste residue, and on the other hand, have limited capacity and fail to fully utilize the unique physicochemical properties of spodumene slag. Spodumene slag itself is rich in calcium (Ca), a medium-level element essential for plant growth, and silicon (Si), a beneficial element, as well as aluminum (Al), which can improve soil structure.

[0004] Currently, commercially available flower potting soil is mostly composed of peat moss, coconut coir, perlite, vermiculite, and other raw materials. While these substrates have good physical structure, they generally suffer from the following drawbacks: First, they are nutrient-poor, especially in terms of medium-level elements (Ca, Mg, S) and beneficial elements (Si), requiring long-term reliance on external chemical fertilizers; second, they are costly, as the extraction of non-renewable resources such as peat moss is subject to environmental restrictions; and third, they have poor structural stability, easily compacting and collapsing after 1-2 planting seasons, resulting in decreased aeration. Therefore, developing a flower potting soil that uses solid waste as a raw material, is rich in calcium and silicon, has a stable structure, and possesses slow-release nutrient function has significant practical importance and market value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a flower nutrient soil based on spodumene slag. This flower nutrient soil, with spodumene slag as the main raw material, possesses advantages such as suitable bulk density, high organic matter content, suitable cation exchange capacity, abundant available calcium, and good pore structure. It is particularly suitable for cultivating high-end flowers that prefer calcium and silicon, thus realizing the resource utilization of industrial solid waste and the greening of horticultural substrates.

[0006] The second objective of this invention is to provide a method for preparing flower nutrient soil based on spodumene slag. This method is simple, easy to operate, and inexpensive.

[0007] To achieve the above technical objectives, the present invention provides a flower nutrient soil based on spodumene slag, characterized in that it comprises the following components in parts by weight:

[0008] 70-90 parts of spodumene slag;

[0009] 3-10 portions of pine needles;

[0010] 5-25 parts of biomass fermentation residue;

[0011] 0.5 to 1 part of microbial inoculant.

[0012] This invention uses spodumene slag as the main matrix component, making full use of the exchangeable calcium and water-soluble silicon components in spodumene slag. The calcium in spodumene slag mainly exists in the form of calcium oxide, which has low solubility and slow-release characteristics. Calcium oxide can form calcium sulfate with sulfur trioxide, which can continuously supply calcium ions throughout the entire flower growth cycle, effectively preventing calcium deficiency physiological diseases in calcium-loving flowers (such as leaf tip burn, new leaf deformation, and root rot). At the same time, silicon can enhance the strength of plant cell walls, improve leaf gloss and disease resistance, and has a significant quality improvement effect on high-end foliage and flowering flowers such as orchids and clivia. Moreover, the spodumene slag particles have an irregular angular shape or a multi-microporous structure, which has a natural mineral skeleton and adsorption and exchange capacity. Pine needles and biomass fermentation residue have characteristics such as low bulk density and high organic carbon, which can further enhance the acid buffering capacity of the matrix and activate mineral calcium, synergistically driving the efficient conversion of spodumene slag into nutrient soil with microorganisms.

[0013] In existing technologies, when spodumene slag or other industrial solid waste is used for soil improvement or matrix preparation, it is usually regarded as "inert filler aggregate" or "low-activity mineral admixture." Its addition is limited by two bottlenecks: first, high admixture levels lead to excessive matrix bulk density and insufficient porosity; second, the potential salt and heavy metal content in the solid waste exerts stress on microorganisms and plant roots. To overcome these bottlenecks, the conventional approach is to reduce the proportion of solid waste, increase the amount of organic matter, and rely on exogenous chemical additives for modification.

[0014] This invention takes a different approach, constructing a self-driven and self-regulating "mineral-organic acid-microorganism coupled reaction system" by combining spodumene slag, pine needles, biomass fermentation residue, and functional microorganisms. This transforms spodumene slag from a passive filler into a "mineral reactor" actively participating in soil formation, thus overcoming the physical and chemical limitations of high admixture. The combination of "pine needles + biomass fermentation residue" constitutes a dual chemical dynamic system of "natural acid slow release" and "organic complex activation," actively and continuously transforming spodumene slag from an inert framework into an active calcium reservoir. Simultaneously, it achieves comprehensive "multi-angle synergy" at several levels, including physical structure, functional microbial domestication, and plant disease resistance, aligning with the core characteristics of spodumene slag (weak acid, dense texture, nutrient deficiency, high calcium) and the core needs of target flowers (high nutrient content, preference for acid and calcium). Its unique synergistic effect is manifested in the following aspects:

[0015] (1) The cascade reaction mechanism of interfacial acid hydrolysis-complexation activation-biomineralization of aluminosilicates

[0016] The first step, targeted erosion and pore expansion by organic acids (biomass material → lithium slag interface): The rosinic acid and phenolic acid produced by the decomposition of pine needles, along with small-molecule organic acids (such as citric acid and malic acid) in the biomass fermentation residue, do not simply lower the overall pH of the substrate. Instead, they interact with the Ca2+ on the surface of spodumene slag particles through carboxyl groups and phenolic hydroxyl groups. 2+ Al 3+ Coordination and adsorption occur, forming high-concentration acid-etched micro-regions at the solid-liquid interface. This targeted acidolysis preferentially dissolves the amorphous calcium silicate and calcium aluminosilicate glass phases in the lithium slag, etching nano- to micron-sized new channels on the particle surface;

[0017] The second step involves the complexation and slow release of calcium ions and the cementation and activation of the aluminum-silicon residue (lithium slag → liquid phase → newly formed colloid): organic acids dissolve Ca... 2+ At the same time, its anions (such as citrate and malate) react with Ca... 2+ It forms stable soluble complexes, preventing premature precipitation of calcium phosphate or calcium carbonate in the micro-zones and ensuring the mobility and plant availability of calcium throughout the matrix;

[0018] The third step involves microbial-driven organic-inorganic composite cementation and aggregate formation (microorganisms → organic acids → active mineral residues): Inoculated Bacillus mucilage or AMF hyphae rapidly proliferate using sugars produced from the decomposition of fruit peels / biogas residues. Their metabolically secreted extracellular polymers are rich in functional groups such as carboxyl and phosphate groups. EPS undergoes ligand exchange and hydrogen bonding with the active aluminosilicate residues formed in the second step, forming an organic-mineral composite film; on the other hand, it is mediated by Ca... 2+ Bridge bonds connect adjacent modified lithium slag particles into stable micro-agglomerates.

[0019] (2) Metabolic coupling-driven pH bistable self-regulation mechanism

[0020] A two-phase buffer system for pH: The weakly acidic humic substances produced by the decomposition of pine needles and the small-molecule organic acids produced by the decomposition of biomass fermentation residue constitute the first-phase buffer system, which can pull the continuously rising pH back to the 6.8~7.2 range; subsequently, the OH- produced by the slow hydrolysis of calcium silicate in lithium slag... - HCO3 formed by the dissolution of CO2 produced by microbial respiration - This constitutes a second-phase buffer system, continuously resisting external acid-base fluctuations during the cultivation period of 60-120 days. This "two-phase buffer" system, composed of organic matter and minerals and continuously driven by microbial metabolism, has a buffering capacity and timeliness far superior to the addition of organic materials or chemical buffers alone, ensuring the long-term stability of the matrix pH under high lithium slag content.

[0021] This invention forms a complete and self-consistent ecological transformation loop of "inorganic mineral activation - organic media driving - microbial network integration," ensuring that a high proportion of industrial solid waste is not excluded from the matrix structure but is actively transformed into a functional entity with skeletal support, slow nutrient release, and biological activity. Specifically, this invention utilizes a three-level structural construction strategy of "biomass materials (physical pore creation) → microbial decomposition and cementation (chemical aggregation) → plant root penetration (biological reinforcement)" to transform originally compact and easily compacted spodumene slag into nutrient soil with a honeycomb-like multi-level aggregate structure. During cultivation, the hyphal network of arbuscular mycorrhizal fungi acts like "micro-steel bars" entwining the aggregates; the roots of the flowers form a macroscopic framework. Through the synergistic maturation effect of flower root penetration, microbial proliferation, and continuous degradation of organic matter, the matrix is ​​transformed in situ into structurally stable and nutrient-rich flower nutrient soil. This synergistic effect ensures that the resulting nutrient soil maintains good looseness, aeration, and aggregate stability even after multiple cycles of wetting and drying and watering.

[0022] As a preferred embodiment, the mass fraction of the spodumene slag is 75-85 parts; and the mass fraction of the pine needles is 5-8 parts.

[0023] As a preferred embodiment, the flower potting soil comprises the following components in parts by weight:

[0024] 70-90 parts of spodumene slag;

[0025] 3-10 portions of pine needles;

[0026] 15-20 parts of biogas residue;

[0027] 0.5 to 1 part of microbial inoculant.

[0028] As a preferred embodiment, the flower potting soil comprises the following components in parts by weight:

[0029] 70-90 parts of spodumene slag;

[0030] 3-10 portions of pine needles;

[0031] 5-15 parts of fermented fruit peel residue;

[0032] 0.5 to 1 part of microbial inoculant.

[0033] As a preferred embodiment, the spodumene slag contains 1.5–5.0 wt% available calcium, 0.2–0.5 wt% water-soluble silicon, and has a pH value of 6.4–7.5. Available calcium refers to both water-soluble and exchangeable calcium. This specific composition of spodumene slag provides a continuous, stable, and sufficient supply of calcium and silicon nutrients to calcium-loving plants (such as clivia, orchids, azaleas, camellias, peonies, hyacinths, and tulips), promoting root development, flower bud differentiation, and enhanced disease resistance.

[0034] As a preferred embodiment, the spodumene slag has a particle size of 0.05~2mm. This particle size is suitable for the matrix system of the present invention.

[0035] As a preferred embodiment, the microbial inoculant includes at least one of Bacillus subtilis, Bacillus mucilaginosus, and arbuscular mycorrhizalfungi (AMF). In a further preferred embodiment, the microbial inoculant includes arbuscular mycorrhizalfungi. Bacillus subtilis primarily decomposes organic matter and produces EPS to promote particle cementation; Bacillus mucilaginosus effectively decomposes mineral potassium and silicon in spodumene slag, converting them into available nutrients that can be absorbed by plants; and arbuscular mycorrhizalfungi can coexist with plant roots, significantly expanding the root absorption area and promoting the absorption of difficult-to-move nutrients such as calcium and phosphorus, which is particularly beneficial for calcium-loving flowers.

[0036] Specifically, the spatial network effect of AMF hyphae in terms of "mineral probes" and "nutrient delivery":

[0037] Conventional high lithium slag content presents another potential risk: even when the overall physical properties of the matrix are satisfactory, the relatively low absolute amount of organic matter and uneven spatial distribution of nutrients reduce the efficiency of plant roots and rhizosphere microorganisms in contacting and activating mineral nutrients. This invention introduces arbuscular mycorrhizal fungi (AMF) as the core functional bacteria, whose effect goes far beyond the conventional "promoting nutrient absorption," instead constructing a living nutrient transport network that permeates the inorganic mineral matrix.

[0038] Mycelia act as “mineral probes”: AMF extra-root mycelia are only 2-20 μm in diameter, much finer than root hairs (about 100-200 μm). They can penetrate the micropores inside lithium slag particles etched by organic acids, which are inaccessible to plant roots, and the narrow pores between particles. They can directly contact the fresh active surface of lithium slag and precisely deliver the protons and small-molecule organic acids secreted by the mycelial tips to the dissolution sites of calcium and silicon, which greatly improves the bio-extraction efficiency of effective nutrients in a unit mass of lithium slag.

[0039] The mycelial network acts as a "direct nutrient transport channel": AMF mycelia form a vast mycelial network (mycelial bridge) spanning several centimeters within the substrate. This network not only connects plant roots to distant lithium slag particles but also establishes transport pathways for water and nutrients between different lithium slag particles. When the calcium ion concentration in a certain micro-area increases due to organic acid etching, AMF mycelia can rapidly transport it to the plant roots or other nutrient-deficient areas via cytoplasmic flow. This direct coupling of the "mycelial network-mineral interface" upgrades the nutrient migration mode, which originally relied on slow diffusion and mass flow, to an active, directional biotransport mode, effectively compensating for the nutrient diffusion limitations that may be caused by high lithium slag content and low organic matter content. This is the key biological mechanism by which this invention can ensure efficient calcium nutrition supply to calcium-loving flowers even with an extreme biomass material ratio as low as 10%.

[0040] As a preferred embodiment, the effective viable bacteria count in the microbial agent is ≥1×10⁻⁶. 10 CFU / g.

[0041] The present invention also provides a method for preparing flower nutrient soil based on spodumene slag. The method involves mixing spodumene slag, pine needles, biomass fermentation residue and microbial inoculant to obtain a substrate, and then planting and cultivating flowers on the substrate to obtain the desired product.

[0042] This invention does not require the application of additional chemical fertilizers; instead, it relies on nutrients released from the decomposition of biomass materials and mineral nutrients activated by microorganisms to supply plant growth. After cultivation, some flowers naturally fall into the substrate, increasing the organic matter content or directly serving as part of the nutrient soil.

[0043] As a preferred embodiment, the cultivation period is 45 to 120 days, during which the substrate moisture content is maintained at 50% to 70% of the maximum field capacity, and the ambient temperature is 15 to 35°C.

[0044] As a preferred option, the flower is a calcium-loving flower.

[0045] As a preferred embodiment, the flower nutrient soil has a bulk density of 0.5–0.8 g / cm³, an organic matter mass fraction of ≥10%, an exchangeable calcium content of ≥3.0 g / kg, a pH of 5.5–7.0, a cation exchange capacity of ≥5 cmol+ / kg, an EC value of 0.9–1.2 mS / cm, and an aeration porosity of ≥10%.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) The flower nutrient soil of the present invention has a high content of spodumene slag, which can continuously and stably release calcium and silicon nutrients. Through the synergistic effect of spodumene slag, specific biomass materials and microbial agents, the nutrient soil has a high organic matter content, is loose and breathable, and has good aggregation stability. It fully meets the national environmental safety standards for greening substrates or flower cultivation substrates. It can be directly used as potting substrate, seedling substrate or courtyard soil improvement material. It is especially suitable for the cultivation of high-end flowers such as orchids, azaleas, thea families and amaryllis families that have special requirements for calcium and silicon elements or strict requirements for substrate structure.

[0048] (2) The method is simple and low-cost, and it can consume a large amount of spodumene slag. The biomass materials used are agricultural or industrial organic waste (sludge, sludge, fruit peel, etc.), and the microbial agents are also commercially available microbial strains. The entire process only requires three main steps: mixing, sowing, and cultivation. It does not require high temperature, high pressure, or expensive equipment. It is easy to operate and can be easily scaled up and promoted. It can achieve self-sufficiency in nutrients without adding any chemical reagents. It is environmentally friendly and has no secondary pollution. After biological cultivation, the excess salt (EC) in spodumene slag is absorbed by plants and fixed by organic matter, and the pH value is stabilized in the neutral or weakly acidic range by the organic acids produced by microbial metabolism. Attached Figure Description

[0049] Figure 1 The images show examples of lily growth during soil cultivation in all experimental cases of this invention.

[0050] Figure 2 These are illustrative images showing the growth of lilies during soil cultivation, representing all experimental examples and comparative examples of this invention. Detailed Implementation Plan

[0051] The present invention will be described in detail and completely below through specific experimental examples and comparative examples, combined with experimental data. However, the scope of protection of the present invention is not limited thereto. Any simple substitution or combination based on the technical solution of the present invention shall fall within the scope of protection of the present invention.

[0052] To verify the effectiveness of the method of the present invention, the following experimental procedure is used to verify the method of the present invention:

[0053] I. Using unmodified spodumene slag as the research object, we conducted cultivation experiments by applying different biomass materials and microorganisms to evaluate the regulatory effect of microbial material application on the physicochemical properties of spodumene slag matrix and the evaluation of flower growth.

[0054] II. Based on the optimal combination ratio for flower growth in Experiment 1, and combined with the basic property analysis of spodumene slag, the effectiveness and stability of the lightweight improvement effect of the substrate were evaluated. At the same time, the physicochemical indicators of the substrate (pH, EC, CEC, organic matter, porosity, bulk density, total nutrients, exchangeable calcium, etc.) were measured to verify the water and fertilizer retention capacity, effective element and organic matter content of the substrate, and to clarify the practical effect of preparing flower nutrient soil with biomass materials and microbial agents.

[0055] The experimental materials are as follows:

[0056] 1. Lithium spodumene slag used in the experimental example:

[0057] The tested spodumene slag was taken from the spodumene slag stockpile of a large lithium salt enterprise. It appears as a grayish-white powder, and easily generates dust after drying. Screening and elemental analysis revealed that its main components are quartz, feldspar, gypsum, and a small amount of residual spodumene. The particle size distribution is between 0.05-2 mm. Basic physicochemical properties and composition are shown in Table 1. As shown in Table 1, the undisturbed spodumene slag has a bulk density of 0.76 g / cm³, extremely low organic matter content (0 g / kg), a CEC of only 4.4 cmol / kg, and a weakly acidic pH (6.42). It cannot be directly used as a substrate for flower growth, but its high angular skeletal structure, potential microporous structure, and abundant trace elements calcium and silicon provide a foundation for constructing high-end flower nutrient soil. The microbial agent used was a wettable powder of Bacillus mucilaginosus with an effective viable count ≥2×10⁻⁶. 10 CFU / g. The flowering plant used in the experiment was lily, which prefers a slightly acidic environment and has a high calcium requirement, in order to evaluate the actual effect of the substrate on the growth of the flower.

[0058] The following standards for target flower nutrient soil are defined with reference to the industry-standard indicators for flower nutrient soil in T / TBD 015-2025: bulk density 0.5~0.8 g / cm³, organic matter mass fraction ≥10%, all nutrient values ​​meet the standards, exchangeable calcium content ≥1.2g / kg, pH 5.5~7.8, cation exchange capacity ≥5 cmol+ / kg, EC value 0.5~1.2 mS / cm, and aeration porosity ≥10%.

[0059] Table 1. Basic physicochemical properties and elemental composition of spodumene slag

[0060]

[0061] 2. Biomass materials used in the test

[0062] The main properties of the following biomass materials are shown in Table 2. Among them, pine needles are used as an improving component; mushroom residue, biogas residue, and fruit peel fermentation residue are used as organic matter and nutrient components. Preparation process of fruit peel fermentation residue: Fresh fruit peels are dried, crushed to a size of 2-3 cm, placed in a sealed glass bottle, moistened with water, and turned over once every 7 days, for a total of 4 times, to obtain fruit peel fermentation residue.

[0063] Table 2 Basic Properties of the Test Biomass Materials

[0064]

[0065] 3. Test microbial inoculants

[0066] Bacillus mucilaginosus inoculum: effective viable count ≥ 1 × 10⁻⁶ 10 CFU / g, purchased from Shandong Yihao Biotechnology Co., Ltd.

[0067] Arbuscular mycorrhizal fungi (AMF) inoculum: mixed spore preparation, spore density ≥60 spores / g, purchased from a microbial manufacturer in Jining, Shandong.

[0068] Bacillus subtilis inoculant: effective viable count ≥ 2 × 10⁻⁶ 10 CFU / g, purchased from Shandong Yihao Biotechnology Co., Ltd.

[0069] 4. Test plants

[0070] Lily: "Sorbonne" variety, prefers slightly acidic environment and calcium.

[0071] Alfalfa: Leguminosae family, taproot system, nitrogen fixation.

[0072] Experimental Example 1 (Y1): Synergistic System of Biogas Sludge-Pine Needles-Bacillus mucilaginosus

[0073] Formula (by dry weight): 79% spodumene slag, 15% biogas residue, 5% pine needle powder, and 1% Bacillus subtilis inoculant.

[0074] Preparation method: Mix spodumene slag, biogas residue, and pine needle powder evenly in a specified ratio, and spray with water to adjust the material moisture content to 40%–45%. Mix Bacillus subtilis inoculant with 10 times its weight of water, spray evenly into the mixture, and stir thoroughly. Fill cultivation pots with a diameter of 30cm and a height of 25cm, with a dry weight of 500g per pot, and pile them up naturally without compaction. Sow two 'Sorbonne' lily bulbs, cover with about 1cm of the mixed substrate, and place in a greenhouse for 90 days of cultivation. During the cultivation period, water twice a week, maintaining the substrate moisture content at about 60% of field capacity, with a temperature of 25-32℃, and do not apply fertilizer.

[0075] Results: After 70 days, the stem length of all potted flower balls was greater than 10 cm. After the flowering period ended, samples were taken for testing 7 days later. The data are shown in Table 3.

[0076] Experimental Example 2 (Y2): Optimized System of Fruit Peel-Pine Needle-Arbuscular Mycorrhizal Fungi

[0077] Formula (by dry weight): 84% spodumene slag, 10% fermented fruit peel residue, 5% pine needle powder, and 1% arbuscular mycorrhizal fungi (AMF) inoculum.

[0078] Preparation method: Mix fermented fruit peel residue with pine needles beforehand and pre-moisten with water, then pile for 24 hours to soften and activate natural microorganisms. Mix spodumene slag with the fermented fruit peel residue and pine needle powder in a dry powder form, then evenly sprinkle in AMF inoculant while spraying water and stirring, maintaining a humidity of 35%–40%. AMF spores should avoid prolonged soaking; therefore, a dry mixing followed by water spraying method is used. Pot the mixture (500 g dry weight of substrate per pot), sow two 'Sorbonne' lily bulbs, cover with a thin layer, and cultivate in a greenhouse for 75 days. During cultivation, in addition to normal watering, water every 15 days with a 500-fold diluted brown sugar solution (0.1% concentration) to promote AMF symbiosis and mycorrhizal development. Other management is the same as in Experiment 1.

[0079] Results: After 75 days, the plant grew vigorously, with white, brush-like roots. The substrate was loose, dark brown in color, and rich in granular structure. The test results are shown in Table 3.

[0080] Experimental Example 3: High-lithium slag-fruit peel-pine needle-arbuscular mycorrhizal fungi system

[0081] Formula (by dry weight): 89% spodumene slag, 5% fermented fruit peel residue, 5% pine needles, and 1% arbuscular mycorrhizal fungi (AMF) inoculum.

[0082] Preparation method: Same as in Experiment 2, but adjust the humidity to 30%–35% after mixing to prevent compaction caused by a high proportion of lithium slag. The sowing amount is the same as in Experiment 2 (sow two 'Sorbonne' lily bulbs), and the cultivation period is 75 days.

[0083] Results: The substrate showed increased relative compactness, but plant roots could still penetrate well, and a clear root hole structure was visible after cultivation. The bulk density was higher than that of Experiment 2, but the exchangeable calcium content was the highest. The test results are shown in Table 3.

[0084] Comparative Example 1 (using mushroom residue as organic material)

[0085] Formula (by dry weight): 80% lithium slag, 19% mushroom residue, and 1% Bacillus subtilis inoculant.

[0086] Preparation method: Same as in Example 1. After 60 days, the substrate bulk density was 0.70 g / cm³, and the organic matter mass fraction was 10%. However, the exchangeable calcium was significantly reduced, and the pH was as high as 7.5, which could not meet the physiological requirements of flowers that prefer calcium and acid. This indicates that although mushroom residue alone can provide nutrients, its calcium slow-release capacity and alkaline neutralization capacity are insufficient, and it cannot stabilize the pH in the slightly acidic range during cultivation.

[0087] Comparative Example 2 (CK1) (Commercially available potting soil)

[0088] The general-purpose flower potting soil, purchased from a well-known brand on an e-commerce platform, mainly consists of peat, perlite, vermiculite, and a small amount of slow-release fertilizer. The flowers were cultivated according to the method described in Example 1.

[0089] Comparative Example 3 (CK2) (pure spodumene slag)

[0090] Unmodified spodumene slag was directly potted, and the same flower bulbs were sown to cultivate the flowers in accordance with the method of Example 1.

[0091] Comparative Example 4 (Inoculation with inactivated microbial agent)

[0092] Formula (by dry weight): 85% spodumene slag, 9% fermented fruit peel residue, 5% pine needles, and 1% inactivated mycorrhizal fungi agent.

[0093] Preparation method: Refer to Example 2.

[0094] The results showed that the substrate contained a large amount of undecomposed pine needles and mushroom debris, indicating a slow humification process. The flowers were weak and stunted, suggesting that functional microorganisms are indispensable for organic matter transformation, acidification regulation, and aggregate formation.

[0095] Comparative Example 5 (No flowers planted)

[0096] The substrate material ratio was the same as in Experiment 2. After mixing, no flowers were sown, and the mixture was left in the same environment for 75 days, turning it over once a week and maintaining humidity. The results showed that the substrate soil structure was loose and powdery, lacking aggregates. Root development was hindered after transplanting the flowers, indicating that plant root exudates and penetration are crucial for forming a stable aggregate structure and a continuously acidified environment. Improvement without plant participation cannot achieve the comprehensive quality of nutrient soil for flowers.

[0097] Comparative Example 6 (Low-calcium solid waste as a substitute for lithium slag)

[0098] In Experiment 2, the spodumene slag was replaced with an equal amount of low-calcium fly ash. The main oxide components of the fly ash were SiO2, Al2O3, CaO, SO3, Fe2O3, and MgO, with contents of 36.8%, 26.9%, 5.1%, 8.4%, 5.2%, and 0.9%, respectively. Other components were the same as in Example 2. After cultivation, the exchangeable calcium content of the corresponding soil matrix was only 430 mg / kg, and the pH value was as high as 11.54.

[0099] Comparative Example 7 (Excessive Addition of Spodumene Slag)

[0100] Formula (by dry weight): 95% spodumene slag, 3% fermented fruit peel residue, 1% pine needles, and 1% arbuscular mycorrhizal fungi (AMF) inoculum.

[0101] The preparation method was the same as in Example 1. The results showed that the substrate had high viscosity and the plant height under this condition was significantly lower than that in the experimental example. After cultivation, the CEC content of the corresponding soil substrate was 4.40 cmol(+) / kg, the organic matter content was only 3%, the pH value was 7.20, and the EC value was 0.68 mS / cm.

[0102] Comparative Example 8 (planting other non-flowering plants)

[0103] The same proportions as in Experiment 2 were used, and ryegrass seeds were sown after mixing. The results showed that ryegrass could germinate and grow under these conditions. After cultivation, the corresponding soil substrate had a CEC content of 4.79 cmol(+) / kg, an organic matter content of only 6%, a pH of 7.13, and an EC value of 0.71 mS / cm. It is clear that its cation exchange capacity and organic matter ratio do not meet the standards for nutrient soil, which indirectly indicates that ryegrass is not as good at converting and utilizing nutrients in the substrate as flower varieties.

[0104] Comparative Example 9 (using only fruit peel fermentation residue as organic material)

[0105] Formula (by dry weight): 79% spodumene slag, 20% fruit peel fermentation residue, and 1% arbuscular mycorrhizal fungi (AMF) inoculum.

[0106] The preparation method was the same as in Example 1. The results showed that the plant height and the degree of flower unfolding of this combination were not as good as those of the experimental example. In addition, the bulk density and maximum wet density of this combination were 0.86 and 1.12 g / cm³, respectively, while the cation exchange capacity was 5.24 cmol(+) / kg. The bulk density and maximum wet density both exceeded the standard expectations.

[0107] The core physicochemical properties of the nutrient soil obtained from each embodiment and some comparative examples are shown in Table 3.

[0108] Table 3. Core physicochemical properties of the nutrient soil prepared for each experimental example and comparative example (measured after cultivation).

[0109]

[0110] Table 4 Nutrient indices of nutrient soil prepared in some experimental examples and comparative examples

[0111]

[0112] As can be seen from Tables 3 and 4:

[0113] (1) Exchangeable calcium content and targeted fertilization advantages: The exchangeable calcium content of the nutrient soils prepared in Experiments 1-3 was all greater than 3100 mg / kg, which is more than twice that of commercially available flower soil (1380 mg / kg). This is directly due to the main raw material status of spodumene slag; the higher its proportion (Experiment 3 > 2 > 1), the higher the exchangeable calcium content. Comparative Example 6 (fly ash) had an exchangeable calcium content of only 430 mg / kg and a pH as high as 11.54, completely losing the core advantage of "calcium-loving and weakly acidic flower nutrient soil", which fully proves the irreplaceable role of spodumene slag as a slow-release calcium nutrient reservoir in this invention.

[0114] (2) Basic nutrient content meets the standard: The total nitrogen, available phosphorus, and available potassium data of Experimental Examples 1 and 2 are all within the limits of basic greening soil. At the same time, the data show that the nutrient content of Experimental Examples is significantly better than that of Comparative Example 2 (pure lithium slag) and Comparative Example 3 (commercially available flower soil). This proves that the flower nutrient soil formed by the method of the present invention has extremely high nutritional value.

[0115] (3) Synergistic effect of AMF and Bacillus mucilaginosus: In Experiments 2 and 3, arbuscular mycorrhizal fungi (AMF) were introduced. Their hyphal networks significantly improved the rhizosphere microenvironment, maintaining good CEC and aeration porosity even with relatively low total organic matter content (15% and 10%). Experiment 1 used Bacillus mucilaginosus, focusing on activating mineral potassium and silicon, further releasing water-soluble silicon content, indicating that different functional bacteria can be flexibly combined according to the needs of flowers. In Comparative Example 4, after removing microorganisms, CEC and porosity dropped sharply, proving that microbial-driven humification and aggregation are essential steps in structure formation.

[0116] (4) The irreplaceable role of plant roots: All physical indicators of Comparative Example 5 (without flowers) deteriorated, especially the aeration porosity (9.5%), which was below the lower limit of 10%. This verifies the decisive role of flower roots in opening up vertical drainage channels and forming stable biological macropores. The results of Comparative Example 8 show that only flowering plants can fully convert lithium slag into nutrient soil.

[0117] (5) Formulation gradient and applicable scope: In Experiment 3, the lithium slag content was as high as 90%, and the resulting nutrient soil had a bulk density of 0.7 g / cm³ and an organic matter mass fraction of 10%, still meeting the basic requirements for high-end flower soil (bulk density < 0.8, organic matter mass fraction ≥ 10%). This proves that the method of the present invention is feasible within a very wide range of lithium slag content (80% to 90%), and can be flexibly adjusted according to the actual flower species (preferring loose or slightly compacted soil), exhibiting extremely high industrial adaptability. The data from Comparative Example 7 show that excessive lithium ash slag addition will reduce the quality of the soil matrix, which is not conducive to flower growth, illustrating the importance of proportion control in the present invention.

[0118] (6) Pine needle powder achieves "structural acid slow release": The tough lignified structure of pine needle powder makes its decomposition slow. The organic acids it contains are slowly released by microorganisms, forming a mild slow-release acid environment controlled by both time and space. This forms a "fast-slow" dual-phase dynamic combination with the rapid acid production of fruit peel residue, ensuring that the acidity at the interface is always in a precise range throughout the entire cultivation cycle, which can efficiently activate calcium without causing acute acid stress to AMF and plant roots.

[0119] AMF mycelial network constructs a "salt biofilter": While absorbing calcium ions, AMF mycelia, with their large specific surface area and the potential points on their cell walls, can adsorb and fix large amounts of Na⁺, K⁺, and other salt ions released from lithium slag, temporarily "locking" them in the biomass of the extraroot mycelia. This is equivalent to constructing a living salt biofilter around the plant roots, ensuring that even with high lithium slag content (up to 90%), the EC value of the rhizosphere microdomain can still be safely maintained at a low level of 0.68-0.88 mS / cm, and further decreases over time.

[0120] In summary, the flower nutrient soil provided by this invention uses a high proportion of spodumene slag as the calcium and silicon source and framework, pine needles and biomass fermentation residue as organic materials, combined with specific microorganisms such as Bacillus mucilaginosus or arbuscular mycorrhizal fungi, and through synergistic cultivation with the root system of Lilium species, to construct a functional nutrient soil that possesses a stable aggregate structure, abundant slow-release calcium and silicon nutrients, and excellent physical properties. This provides a practical, green, and environmentally friendly solution for the high-value utilization of massive amounts of spodumene slag in the lithium battery industry, with significant economic, ecological, and social benefits.

Claims

1. A flower nutrient soil based on spodumene slag, characterized in that: Includes the following components by weight: 70-90 parts of spodumene slag; 3-10 portions of pine needles; 5-25 parts of biomass fermentation residue; 0.5 to 1 part of microbial inoculant.

2. The flower nutrient soil based on spodumene slag according to claim 1, characterized in that: The mass fraction of the spodumene slag is 75-85 parts; The pine needles are present in a mass fraction of 5 to 8 parts.

3. A flower nutrient soil based on spodumene slag according to claim 1 or 2, characterized in that: The biomass fermentation residue includes biogas residue and / or fruit peel fermentation residue.

4. The flower nutrient soil based on spodumene slag according to claim 1, characterized in that: The flower potting soil comprises the following components in parts by weight: 70-90 parts of spodumene slag; 3-10 portions of pine needles; 15-20 parts of biogas residue; 0.5 to 1 part of microbial inoculant.

5. The flower nutrient soil based on spodumene slag according to claim 1, characterized in that: The flower potting soil comprises the following components in parts by weight: 70-90 parts of spodumene slag; 3-10 portions of pine needles; 5-15 parts of fermented fruit peel residue; 0.5 to 1 part of microbial inoculant.

6. A flower nutrient soil based on spodumene slag according to claim 1 or 2, characterized in that: The spodumene slag contains 1.5-5.0 wt% available calcium, 0.2-0.5 wt% water-soluble silicon, and has a pH value of 6.4-7.

5.

7. A flower nutrient soil based on spodumene slag according to claim 1 or 2, characterized in that: The particle size of the spodumene slag is 0.05~2mm.

8. A flower nutrient soil based on spodumene slag according to claim 1, characterized in that: The microbial agent includes at least one of Bacillus subtilis, Bacillus mucilaginosus, and arbuscular mycorrhizal fungi. The effective viable bacteria count in the microbial agent is ≥1×10⁻⁶. 10 CFU / g or spore density ≥60 spores / g.

9. A method for preparing flower nutrient soil based on spodumene slag according to any one of claims 1 to 8, characterized in that: A substrate is prepared by mixing spodumene slag, pine needles, biomass fermentation residue and microbial inoculant. Flowers are then planted and cultivated on the substrate.

10. The method for preparing flower nutrient soil based on spodumene slag according to claim 9, characterized in that: The cultivation cycle is 45 to 120 days. During the cultivation period, the substrate moisture content is maintained at 50% to 70% of the maximum field capacity, and the ambient temperature is 15 to 35℃.

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