A method for preparing an artificial soil

Abstract

The application belongs to the field of agricultural technology, and particularly relates to a preparation method of artificial soil, which comprises the steps of two-stage fermentation, construction of a nano-mineral and biochar composite skeleton system, inoculation of a composite microbial agent, soil activation and the like. The application simulates a natural soil formation mechanism in a systematic manner, combines soil, biology and material science, focuses on three key dimensions of organic matter gradient conversion, mineral skeleton precise construction and microbial community cultivation, improves multi-source organic waste cooperative aerobic fermentation, develops nano-scale mineral activation and biochar modification technology to construct a multi-level pore structure similar to a honeycomb, and implants a specific functional microbial community, so that a soil self-sustaining ecosystem is rapidly established, and high humus, high structural stability and high biological activity of the soil are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural technology, in particular to a preparation method of artificial soil. BACKGROUND

[0002] Soil quality degradation has become a key issue threatening the sustainability of the ecosystem. The traditional fertile soil has three advantages: rich organic matter content, ideal soil aggregate structure, and active microbial community. However, it usually takes decades or even hundreds of years of geological process to form such soil. Artificial soil cultivation is expected to efficiently cultivate "super soil" with similar characteristics or even better performance under controllable conditions.

[0003] However, the existing artificial cultivation of high-fertility soil technology has significant limitations. The organic improvement method relies on the addition of organic solid waste compost products. Although the traditional aerobic fermentation compost method has high organic matter content, the water-stable aggregate proportion is low, and the cementing material is lacking, which causes the structure to collapse quickly after being decomposed or coming into contact with water, resulting in soil structure collapse. The mineral additive method improves the structure by adding nano mineral powder to improve the nutrients or improve the structure, but it does not solve the problem of nano particle aggregation failure, the porosity is improved by a small margin, and it is not coordinated with organic matter, resulting in unbalanced nutrient release. The microbial inoculation method introduces functional bacteria, but due to the lack of carriers and long-term energy supply, the survival time of the bacteria in the soil is short, and the colonization rate is low. SUMMARY

[0004] The present application aims to solve the problem of significant limitations in the current artificial cultivation of high-fertility soil technology, and proposes a preparation method of artificial soil. The above-mentioned purpose can be achieved by the following technical solutions:

[0005] A preparation method of artificial soil, comprising the following steps:

[0006] Step one) Two-stage fermentation: fermenting the biomass raw material at 60-65°C and an oxygen concentration of >10% for 8-15 days; then performing closed anaerobic fermentation at 35-40°C for 20-30 days to obtain fermented organic matter;

[0007] Step two) mixing mineral powder containing mineral nutrients with sandy soil to obtain a mineral-sandy soil mixture; the particle size of the mineral powder is less than 100 nm;

[0008] Step three) immersing biochar in an ammonium magnesium phosphate solution, and treating the ammonium magnesium phosphate solution by vacuum to make it enter the pores of the biochar, to obtain biochar loaded with ammonium magnesium phosphate; then calcining the biochar loaded with ammonium magnesium phosphate at 150-180°C to obtain modified biochar; mixing the mineral-sandy soil mixture and the modified biochar at a weight ratio of 30-50:5-8 to obtain a mineral-biochar skeleton;

[0009] Step 4) After culturing the bacterial strains containing slow-growing soybean rhizobia, azospirobacter, Penicillium oxalate, Bacillus megaterium, Azotobacter chrysogenum, and Trichoderma viride, the strains are adsorbed onto the carrier to form microspheres with a diameter of 2-3 mm, thus obtaining the bacterial agent.

[0010] Step 5) Mix fermented organic matter, mineral-biochar framework, garden soil and microbial agent, and add trehalose as an activator. Cultivate for 7 days under shaded and aerated conditions to obtain the artificial soil.

[0011] The weight ratio of fermented organic matter, mineral-biochar skeleton, garden soil, and microbial agent is 15-25:25-35:45~55:2-5.

[0012] This invention improves the multi-source organic matter fermentation method by changing the traditional one-stage aerobic fermentation to a two-stage fermentation of "aerobic + anaerobic". By increasing the anaerobic stage, the amount of humic acid substances generated is increased. Humic acid substances are key cementing substances for the formation of soil aggregates, and the proportion of water-stable aggregates in the fermentation products is also greatly increased.

[0013] This invention constructs a mineral-biochar framework, forming a honeycomb structure. This rigid framework supports soil particles, promoting the formation of stable aggregates. The abundant pores in the framework directly enhance soil aeration and permeability, preventing root zone clogging even at high organic matter content. The biochar surface and mineral components can adsorb nutrients, slowing down decomposition and release rates, thus achieving a sustained and balanced nutrient supply.

[0014] This invention introduces beneficial microbial species and improves the survival time and colonization rate of the microorganisms through carrier adsorption, preparation of microbial agent microspheres, and nutrient supply.

[0015] Optionally, the biomass raw material in step one) includes the following components in parts by weight:

[0016] 20-30 parts by weight of herbaceous straw, 15-25 parts by weight of woody materials, 25-35 parts by weight of poultry and livestock manure, and 10-20 parts by weight of leguminous green manure;

[0017] Preferably, the particle size of herbaceous straw is 5-10 mm; the particle size of woody materials is 3-5 mm; the particle size of poultry and livestock manure is less than 10 mm; and the particle size of legume green manure is 5-10 mm.

[0018] Preferably, in step one), the biomass raw material is fermented at 60-65°C and with an oxygen concentration >10% for 8-15 days. During the fermentation process, the moisture content of the first stage of fermentation is controlled to be 55%-65%.

[0019] Preferably, the herbaceous straw is corn stalk, the woody material is garden waste, the poultry and livestock manure is chicken manure, and the legume green manure is milkvetch.

[0020] Optionally, after 15 to 20 days of closed anaerobic fermentation, kaolin is added to the biomass raw material and closed anaerobic fermentation continues for 5 to 10 days.

[0021] Preferably, the amount of kaolin added is 1%.

[0022] Optionally, in step two, ore powder containing selenium, phosphorus, calcium, iron, copper, zinc, manganese and magnesium elements is mixed with sand to obtain a mineral sand mixture; the ore powder has a particle size of less than 100 nm and the weight ratio of ore powder to sand is 50-80:300-500.

[0023] The ore powder contains 10-15 mg / kg of selenium, 250-350 mg / kg of phosphorus, 75-125 g / kg of calcium, 25-75 mg / kg of iron, 5-15 mg / kg of copper, 5-15 mg / kg of zinc, 75-152 mg / kg of manganese, and 25-75 g / kg of magnesium.

[0024] Optionally, the biochar is at least one of rice husk biochar, corn cob biochar, and coconut shell biochar, with a specific surface area >300 m². 2 / g.

[0025] Optionally, in step three), the biochar is immersed in a saturated magnesium ammonium phosphate solution, and after being evacuated to -0.8 to -0.5 MPa, it is restored to normal pressure and circulated three times to ensure that the solution fully enters the pores of the biochar.

[0026] Optionally, carbon-calcium micro-aggregates are added to the artificial soil obtained in step five, with the addition amount being 2-4% of the weight of the artificial soil; wherein the carbon-calcium micro-aggregates are formed by mixing modified biochar and nano-calcium carbonate powder at a ratio of 2:1 and reacting them under humid conditions at 58-62°C for 18-30 hours.

[0027] Optionally, 0.3-0.8% of magnesium aluminum carbonate layered double hydroxide may be added to the artificial soil obtained in step five.

[0028] Optionally, slow-release fertilizer may be added to the artificial soil obtained in step five.

[0029] The slow-release fertilizer includes a fertilizer core;

[0030] The fertilizer core is covered by an inner coating layer, which includes phosphogypsum and humic acid.

[0031] The outer side of the inner coating layer is covered by an outer coating layer, which includes dolomite powder and quicklime.

[0032] The technical solution of this invention has the following advantages:

[0033] This technical solution aims to cultivate high-performance soils efficiently under controlled conditions by systematically simulating the natural soil formation mechanism and combining modern soil biology and materials science innovations.

[0034] Unlike the single fermentation mode of traditional composting, this scheme proposes a two-stage fermentation mode of "high temperature aerobic + mesophilic anaerobic", combined with fulvic acid-montmorillonite promoter, which greatly improves the HA / FA ratio and increases the formation rate of water-stable aggregates, thus overcoming the bottleneck of poor structural stability in traditional composting.

[0035] This invention proposes a nano-mineral and biochar composite framework system that achieves synergistic micropore development across large, medium, and micropores, mimicking a "honeycomb" structure. This ensures both air permeability and high water retention, solving the problems of easy compaction and poor pore structure in traditional artificial soils. Furthermore, the humic acid-mineral coordination bonds enhance aggregate stability, resulting in low organic matter loss under heavy rain.

[0036] Unlike traditional methods that rely solely on mineral nutrient additions for soil cultivation, this approach constructs a synergistic system of "organic matter-minerals-microorganisms" and employs a three-tiered inoculation of functional microorganisms. This activates nutrient cycling and disease resistance mechanisms through specific microbial combinations, thereby enhancing soil vitality. Furthermore, the three-tiered microbial system possesses strong self-sustaining capabilities, eliminating the need for short-term supplementation.

[0037] To mimic the nutrient supply rhythm of natural soil, this solution features a core-shell structure slow-release fertilizer design. Unlike traditional methods of directly adding fertilizer, this solution prevents nutrient loss and provides a more sustained nutrient supply.

[0038] The soil prepared by this method has a higher bulk density due to the addition of a large amount of sand, allowing for direct planting of plants. While natural high-quality soils such as peat moss have high organic matter content, their low bulk density makes them prone to lodging and root adhesion when planted directly. In contrast, the soil of this invention has high root adhesion, making it less prone to lodging. It maintains high organic matter and nutrient content while also ensuring structural stability, which is a significant advantage over natural high-quality soils such as peat moss. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0040] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0042] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0043] This invention proposes an artificial soil cultivation technology that aims to systematically simulate natural soil formation mechanisms. Combining soil, biological, and materials science, it focuses on three key dimensions: organic matter cascade transformation, precise mineral framework construction, and targeted cultivation of microbial communities. Through the synergistic fermentation of multi-source organic waste (straw, manure, etc.), combined with nanoscale mineral activation and biochar modification technologies, a multi-level porous structure resembling a honeycomb is constructed. Simultaneously, specific functional microbial communities are implanted to rapidly establish a self-sustaining soil ecosystem, achieving high humus content, high structural stability, and high biological activity in the cultivated soil. The invention specifically includes the following steps:

[0044] Step 1) Two-stage fermentation: Ferment the biomass raw material at 60-65°C and oxygen concentration >10% for 8-15 days; then, conduct closed anaerobic fermentation at 35-40°C for 20-30 days to obtain fermented organic matter.

[0045] Step 2) Mix the mineral powder containing mineral nutrients with sand to obtain a mineral sand mixture; the particle size of the mineral powder is less than 100 nm.

[0046] Step 3) Immerse the biochar in a magnesium ammonium phosphate solution, and use vacuum treatment to allow the magnesium ammonium phosphate solution to enter the pores of the biochar to obtain magnesium ammonium phosphate-loaded biochar; then calcine the magnesium ammonium phosphate-loaded biochar to obtain modified biochar; mix the mineral sand mixture and the modified biochar to obtain a mineral-biochar framework.

[0047] Step 4) After culturing the bacterial strains containing slow-growing soybean rhizobia, azospirobacter, Penicillium oxalate, Bacillus megaterium, Azotobacter chrysogenum, and Trichoderma viride, the strains are adsorbed onto the carrier to form microspheres with a diameter of 2-3 mm, thus obtaining the bacterial agent.

[0048] Step 5) Mix fermented organic matter, mineral-biochar framework, garden soil and microbial agent, and add trehalose as an activator. Cultivate for 7 days under shaded and aerated conditions to obtain the artificial soil.

[0049] Furthermore, the two-stage fermentation in step one) specifically includes:

[0050] First stage of fermentation (temperature-controlled and oxygen-consuming stage): The mixture is maintained at 60-65°C for 8-15 days, using a forced ventilation system (ventilating for 10 minutes per hour) to promote the rapid decomposition of easily degradable organic matter by aerobic microorganisms (mainly actinomycetes and thermophilic bacteria). The key control points in this stage are a moisture content of 55%-65% and an oxygen concentration >10%, which can ensure the effective degradation of lignocellulose without the formation of mold.

[0051] Fermentation raw material ratio (on dry weight):

[0052] Herbaceous straw, 30%, particle size 3-5mm, provides a fast-acting carbon source;

[0053] Woody material, 25%, 3-5mm, long-lasting carbon source, maintains structure;

[0054] Poultry and livestock manure, 25%, ≤2mm, nitrogen source and microbial strains;

[0055] Leguminous green manure, 20%, 5-10mm, biological nitrogen fixation, mineral activation.

[0056] Second-stage fermentation (anaerobic humification stage): After cooling to 35-40°C, the mixture is transferred to a closed fermentation tank, and a humification promoter (0.1% fulvic acid and 0.5% montmorillonite powder, both based on the dry weight of the raw materials) is added for 20 days of anaerobic fermentation. During this stage, the humification ratio (HA / FA) ​​increases to 1.8-2.0, generating a large amount of humic acid compounds—key cementing substances for soil aggregate formation and carbon sequestration. The final product has an organic matter content of over 65%, with water-stable aggregates accounting for over 50%.

[0057] The precise proportions and two-stage fermentation process described above are among the core innovations of this invention. Unlike the single fermentation mode of traditional composting, this technology adopts a phased control strategy to maximize organic matter conversion efficiency and humic yield.

[0058] Furthermore, the method in step two includes: ball milling selenium ore powder (providing plant-available selenium), phosphate rock powder (slow-release phosphorus source), calcium ore powder (promoting agglomerate formation), iron ore powder (participating in redox reactions), and an auxiliary trace element combination (ore powder containing Cu, Zn, Mn, and Mg) to a particle size <100 nm and a specific surface area of ​​200-400 m². 2 / g, significantly improving elemental availability. Then, the ball-milled ore powder is mixed with sand at a weight ratio of 50-80:300-500. The mixture is then stirred in a mixer at 45 rpm for 30 minutes to ensure uniform dispersion.

[0059] Among them, sandy soil is soil with a sand content (particle size 1-0.05 mm) greater than 50%, and washed sandy soil is preferred.

[0060] The ore powder contains 10-15 mg / kg of selenium, 250-350 mg / kg of phosphorus, 75-125 g / kg of calcium, 25-75 mg / kg of iron, 5-15 mg / kg of copper, 5-15 mg / kg of zinc, 75-152 mg / kg of manganese, and 25-75 g / kg of magnesium.

[0061] Furthermore, step three includes:

[0062] Preparation of modified biochar: Rice husk, corn cob, and coconut shell biochar (specific surface area > 300 m²) were selected. 2 Using materials such as magnesium ammonium phosphate (Mg2+) as the base material, the nutrient retention capacity is enhanced by a magnesium ammonium phosphate loading process.

[0063] Biochar was immersed in a saturated magnesium ammonium phosphate solution (20% concentration), and circulated under vacuum pressure (-0.8~-0.5 MPa) three times to ensure the solution fully penetrated the micropores. It was then calcined at 150-180℃ to solidify, forming a microporous slow-release structure. The modified biochar exhibited an increased cation exchange capacity (CEC) of 15-20 cmol / kg and an anion exchange capacity (AEC) of 5-8 cmol / kg, becoming a highly efficient "nutrient reservoir." In the nano-mineral and biochar composite framework system, the ratio of nano-minerals to modified biochar was 30-50:5-8, and the mixture was homogeneous to form a mineral-biochar framework.

[0064] The aforementioned nano-mineral and biochar composite framework system precisely simulates the "honeycomb" structure of chernozem, solving the problems of easy compaction and poor pore structure in traditional artificial soils. The cultivated soil has suitable porosity, achieving an ideal pore distribution through hierarchical construction: macropores (>30μm, aeration and water permeability) are provided by straw fragments (3-10mm) and biochar (2-4mm); mesopores (0.2-30μm, water retention and root growth) depend on organic-mineral composite aggregates; micropores (<0.2μm, nutrient adsorption) are contributed by the surface of nano-minerals and biochar micropores. By controlling the addition amount of different components, the proportions of macropores, mesopores, and micropores are controlled, resulting in a final product with a total porosity >55% and an aeration / water retention ratio ≈1:2, approaching the ideal chernozem structure.

[0065] The tertiary inoculation of functional microorganisms in step four is the core of this scheme to achieve "soil vitality". It activates nutrient cycling and disease resistance mechanisms through specific microbial community combinations, and specifically includes the following steps:

[0066] Compound microbial agent formulation: slow-growing soybean rhizobium (Bradyrhizobium japonicum) + nitrogen-fixing spirochete (Azospirillum brasilense), inoculation amount 10. 6 CFU / g; Phosphate-solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculum size 10 5 CFU / g; Carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculum size 10 4 CFU / g.

[0067] Propagation and embedding: Each strain is propagated to the target concentration in a special culture medium (such as nitrogen-free culture medium for nitrogen-fixing bacteria), mixed in proportion, and adsorbed onto a calcium alginate gel carrier (containing 5% humic acid), granulated into microspheres with a diameter of 2-3 mm, and stored at low temperature.

[0068] Step five specifically includes:

[0069] The fermented organic matter, mineral-biochar framework, garden soil, and microbial inoculant are mixed in a weight ratio of 15-25:25-35:45~55:2-5, and the moisture content is adjusted to 40%. 0.5% trehalose activator is added. The mixture is incubated under shaded conditions for 7 days, with daily turning and aeration to promote microbial colonization. Microbial activity is tested (FDA hydrolysis rate >5 μg / g·h) before use. This method results in soil microbial biomass far exceeding that of conventional farmland soils, and a significant increase in functional diversity index.

[0070] Garden soil is taken from farmland or vegetable gardens, and its basic physical and chemical properties include: bulk density 1.1-1.3 (g / cm³). 3 Organic matter content 1-3%, total nitrogen content 0.08%-0.15%, available phosphorus (P2O5) 5-20 mg / kg, available potassium (K2O) 80-200 mg / kg, cation exchange capacity (CEC) 10-20 cmol / kg.

[0071] In some specific implementations, to enhance carbon sequestration and nutrient slow release capabilities, this scheme proposes a humic substance-nanomineral covalent bonding technology:

[0072] Humic lock-in: Adding nano-kaolin (1% addition) in the later stage of the second fermentation stage allows the aluminum hydroxyl groups (Al-OH) on its surface to form a stable coordination complex Al-OH / COOH with the carboxyl groups (-COOH) of humic acid, which greatly enhances the decomposition resistance of humic acid.

[0073] Preparation and addition of biochar-mineral microaggregates: Carbon-calcium microaggregates are added to artificial soil at a rate of 2-4% of soil weight. These carbon-calcium microaggregates are formed by mixing modified biochar and nano-calcium carbonate powder in a 2:1 ratio and reacting at 60°C under humid conditions for 24 hours (size 0.5-2 mm). This structure reduces the organic carbon mineralization rate and prolongs the half-life. The addition amount is 2-4% of soil weight.

[0074] Layered double hydroxide addition: Adding 0.5% magnesium aluminum carbonate type layered double hydroxide to the finished soil product can fix HCO3- between its layers. - It gradually transforms into CO3 in the soil solution. 2- This enables inorganic carbon sequestration, thereby increasing carbon sink capacity.

[0075] In some specific implementations, in order to mimic the nutrient supply rhythm of natural soil, this scheme adds core-shell structured slow-release fertilizer to the artificial soil.

[0076] Preparation of slow-release fertilizer in soil bags:

[0077] Core preparation involves mixing N:P₂O₅:K₂O in a ratio of 12:18:10, where:

[0078] Nitrogen source: well-rotted manure (containing 3.5% N) + urea (30%); Phosphorus source: nano-phosphate rock powder (total phosphorus >28%) + magnesium ammonium phosphate (10%); Potassium source: potassium feldspar nano powder (K2O >9%) + potassium sulfate (20%); and chelated trace elements (Fe, Zn, B, etc.) are added.

[0079] The coating process involves first granulating the core into particles with a diameter of 3-5mm, and then coating them in two stages, including:

[0080] The inner coating layer consists of phosphogypsum (10%) and humic acid (5%), forming an ion exchange layer;

[0081] The outer coating layer consists of dolomite powder (0.1 mm particle size, 15% addition) and quicklime (5%) to provide pH buffering.

[0082] The final product forms particles with a diameter of 6-8 mm. This fertilizer releases into the soil in three stages: the outer layer dissolves and adjusts the pH within 24 hours; the inner layer gradually releases NPK over 7-14 days; and the core layer slowly dissolves over 1-2 months. Compared to ordinary chemical fertilizers, nitrogen and phosphorus loss rates are significantly reduced.

[0083] Mix the slow-release granules with the soil at a mass ratio of 1:50-200.

[0084] The above-mentioned artificial soil can be used in the following ways:

[0085] For direct application: lay a layer ≥30cm thick and use with a drip irrigation system. Alternatively, for degraded land improvement: apply 5-20 tons per acre, plow to a depth of 25cm, and then plant.

[0086] Example 1

[0087] Step 1) Multi-source organic matter cascade fermentation

[0088] Corn stalks (300kg), garden waste (250kg), chicken manure (250kg), and milkvetch (200kg) were crushed and mixed, then fed into a sampling tank fermentation system. The temperature was controlled at 63±2°C, and the mixture was turned once a day for 10 days. A humification promoter (fulvic acid 0.35kg and montmorillonite powder 1.75kg) was added, and the mixture was transferred to a closed fermentation tank for secondary fermentation. The secondary fermentation was maintained at 38±2°C, and the mixture was turned once a week for 20 days. The fermentation was considered complete when C / N < 20, HA / FA > 1.8, and water-stable aggregates > 50%.

[0089] Step 2) Preparation and activation of nano-minerals

[0090] Weigh out 80 kg of nano-mineral powder according to the formula and premix it with 300 kg of washed sand to form a sand-mineral mixture. The nano-mineral powder is ball-milled to a particle size <100 nm and a specific surface area of ​​300 m². 2 / g, significantly improving element availability. After addition, mix in a mixer at 45 rpm for 30 minutes to ensure uniform dispersion.

[0091] The nano mineral powder contains the following nutrients by mass fraction: selenium: 12mg / kg; phosphorus: 300mg / kg; calcium: 100g / kg; iron: 50mg / kg; copper: 10mg / kg; zinc: 10mg / kg; manganese: 100mg / kg; magnesium: 50g / kg.

[0092] Step 3) Preparation of mineral-biochar framework:

[0093] Preparation of modified biochar: Rice husk biochar (specific surface area > 300 m²) was selected. 2 Using magnesium ammonium phosphate (MgA) as the base material, a magnesium ammonium phosphate loading process was employed to enhance its nutrient retention capacity. 60 kg of biochar was immersed in a 20% saturated magnesium ammonium phosphate solution, and vacuum pressurized (-0.8 MPa) for three cycles to ensure the solution fully penetrated the micropores. The solution was then calcined at 150°C to solidify, forming a microporous slow-release structure.

[0094] Preparation of mineral-biochar framework: The above-mentioned sand-mineral mixture and modified biochar were mixed in a twin-shaft mixer to obtain the mineral-biochar framework.

[0095] Step 4) Preparation of compound microbial agent:

[0096] Inoculation culture: slow-growing soybean rhizobium (Bradyrhizobium japonicum) + azospirillum brasilense, inoculation amount 10 6 CFU / g; Phosphate-solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculum size 10 5 CFU / g; Carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculum size 10 4 CFU / g.

[0097] Propagation and embedding: Each strain was propagated to the target concentration in a special culture medium (such as nitrogen-free culture medium for nitrogen-fixing bacteria), mixed in proportion, and then adsorbed onto a calcium alginate gel carrier (containing 5% humic acid). The mixture was then granulated into microspheres with a diameter of 3 mm and stored at low temperature.

[0098] Step 5) Soil Activation:

[0099] Fermented organic matter (200 kg), mineral framework (300 kg), and garden soil (475 kg) were mixed, and then microbial inoculants (20 kg) and trehalose activator (5 kg) were added. The mixture was piled up for activation, covered with a shade net, and turned over once a day for 7 days to obtain the artificial soil.

[0100] Step 6) Soil preparation:

[0101] Preparation of slow-release fertilizer granules: Well-rotted chicken manure and urea are used as nitrogen sources, nano-phosphate rock powder and magnesium ammonium phosphate are used as phosphorus sources, and potassium feldspar nano powder and potassium sulfate are used as potassium sources. The ratio of nitrogen, phosphorus, and potassium sources N:P2O5:K2O is controlled at 12:18:10. After mixing, the mixture is granulated to form granules with a diameter of 3-5mm. Then, it is coated in two stages. The inner coating layer uses phosphogypsum (10% addition) + humic acid (5%), and the outer coating layer uses dolomite powder (0.1mm particle size, 15% addition) + slaked lime (5%).

[0102] Soil preparation includes: testing microbial activity (FDA hydrolysis rate >5μg / g·h), adjusting pH to 6.5-7.0 (using dolomite powder / quicklime), adding the above-mentioned slow-release fertilizer granules (10kg) and LDHs carbon fixation agent (5kg), controlling the final moisture content at 25%-30%, and packaging and storing.

[0103] Example 2

[0104] Compared to Example 1, after 15-20 days of closed anaerobic fermentation in step one), kaolin (1% addition) was added to the biomass raw material, and closed anaerobic fermentation continued for another 5-10 days, allowing the aluminum hydroxyl groups (Al-OH) on the surface of the kaolin to form a stable coordinate complex Al-OH / COOH with the carboxyl groups (-COOH) of humic acid. The remaining steps were the same as in Example 1.

[0105] Example 3

[0106] Compared to Example 1, in this example, biochar-mineral micro-aggregates were added during soil preparation in step five), at an amount of 3% of the soil weight. The biochar-mineral micro-aggregates were formed by mixing modified biochar and nano-calcium carbonate powder in a 2:1 ratio and reacting the mixture at 60°C under humid conditions for 24 hours to form carbon-calcium micro-aggregates. The resulting biochar-mineral micro-aggregates (size 0.5-2 mm) were then formed. The remaining steps were the same as in Example 1.

[0107] Example 4

[0108] Step 1) Two-stage fermentation: Crush and mix corn stalks (300kg), garden waste (250kg), chicken manure (250kg), and milkvetch (200kg) and put them into the first stage of fermentation: a sampling tank fermentation system, ferment for 15 days at 60°C and oxygen concentration >10%; then, conduct closed anaerobic fermentation for 20-30 days at 35-40°C to obtain fermented organic matter;

[0109] Step 2) Weigh out 80 kg of nano-mineral powder according to the formula and premix it with 500 kg of washed sand to form a sand-mineral mixture. The nano-mineral powder is ball-milled to a particle size <100 nm and a specific surface area of ​​300 m². 2 / g, significantly improving element availability. After addition, mix in a mixer at 45 rpm for 30 minutes to ensure uniform dispersion.

[0110] The nano mineral powder contains the following nutrients by mass fraction: selenium: 12mg / kg; phosphorus: 300mg / kg; calcium: 100g / kg; iron: 50mg / kg; copper: 10mg / kg; zinc: 10mg / kg; manganese: 100mg / kg; magnesium: 50g / kg.

[0111] Step 3) Preparation of mineral-biochar framework: Preparation of modified biochar: Corn cob biochar (specific surface area > 300 m²) was selected. 2 Using magnesium ammonium phosphate (MgA) as the base material, a magnesium ammonium phosphate loading process was employed to enhance its nutrient retention capacity. 60 kg of biochar was immersed in a 20% saturated magnesium ammonium phosphate solution, and vacuum pressurized (-0.8 MPa) for three cycles to ensure the solution fully penetrated the micropores. The solution was then calcined at 150°C to solidify, forming a microporous slow-release structure.

[0112] Preparation of mineral-biochar framework: The above-mentioned sand-mineral mixture and modified biochar were mixed in a twin-shaft mixer to obtain the mineral-biochar framework.

[0113] Step 4) Preparation of compound microbial agent:

[0114] 1. Inoculation and culture: slow-growing soybean rhizobium (Bradyrhizobium japonicum) + azospirillum brasilense, inoculation amount 10. 6 CFU / g; Phosphate-solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculum size 10 5 CFU / g; Carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculum size 10 4 CFU / g.

[0115] 2. Propagation and embedding: Each strain is propagated to the target concentration in a special culture medium (such as nitrogen-free culture medium for nitrogen-fixing bacteria), mixed in proportion, and then adsorbed onto a calcium alginate gel carrier (containing 5% humic acid). The mixture is then granulated into microspheres with a diameter of 3 mm and stored at low temperature.

[0116] Step 5) Soil Activation: Mix fermented organic matter (250 kg), mineral framework (350 kg), and garden soil (550 kg), then add microbial inoculants (20 kg) and trehalose activator (5 kg). Pile the mixture for activation, cover with a shade net, and turn it over once a day for 7 days. The resulting artificial soil is obtained.

[0117] Step 6) Soil preparation: Test microbial activity (FDA hydrolysis rate >5μg / g·h), adjust pH to 6.5-7.0 (using dolomite powder / quicklime), add the above slow-release fertilizer granules (10kg) and LDHs carbon fixation agent (5kg), and finally control the moisture content to 25%-30%, then package and store.

[0118] Example 5

[0119] Step 1) Two-stage fermentation: Crush and mix corn stalks (300kg), garden waste (250kg), chicken manure (250kg), and milkvetch (200kg) and put them into the first stage of fermentation: a sampling tank fermentation system, ferment for 8 days at 65°C and oxygen concentration >10%; then, under closed anaerobic fermentation at 35-40°C for 20-30 days to obtain fermented organic matter;

[0120] Step 2) Weigh out 50 kg of nano-mineral powder according to the formula and premix it with 300 kg of washed sand to form a sand-mineral mixture. The nano-mineral powder is ball-milled to a particle size <100 nm and a specific surface area of ​​300 m². 2 / g, significantly improving element availability. After addition, mix in a mixer at 45 rpm for 30 minutes to ensure uniform dispersion.

[0121] The nano mineral powder contains the following nutrients by mass fraction: selenium: 12mg / kg; phosphorus: 300mg / kg; calcium: 100g / kg; iron: 50mg / kg; copper: 10mg / kg; zinc: 10mg / kg; manganese: 100mg / kg; magnesium: 50g / kg.

[0122] Step 3) Preparation of mineral-biochar framework: Preparation of modified biochar: Coconut shell biochar (specific surface area > 300 m²) was selected. 2 Using magnesium ammonium phosphate (MgA) as the base material, a magnesium ammonium phosphate loading process was employed to enhance its nutrient retention capacity. 60 kg of biochar was immersed in a 20% saturated magnesium ammonium phosphate solution, and vacuum pressurized (-0.8 MPa) for three cycles to ensure the solution fully penetrated the micropores. The solution was then calcined at 150°C to solidify, forming a microporous slow-release structure.

[0123] Preparation of mineral-biochar framework: The above-mentioned sand-mineral mixture and modified biochar were mixed in a twin-shaft mixer to obtain the mineral-biochar framework.

[0124] Step 4) Preparation of compound microbial agent

[0125] 1. Inoculation and culture: slow-growing soybean rhizobium (Bradyrhizobium japonicum) + azospirillum brasilense, inoculation amount 10. 6 CFU / g; Phosphate-solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculum size 10 5 CFU / g; Carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculum size 10 4CFU / g.

[0126] 2. Propagation and embedding: Each strain is propagated to the target concentration in a special culture medium (such as nitrogen-free culture medium for nitrogen-fixing bacteria), mixed in proportion, and then adsorbed onto a calcium alginate gel carrier (containing 5% humic acid). The mixture is then granulated into microspheres with a diameter of 3 mm and stored at low temperature.

[0127] Step 5) Soil Activation

[0128] Fermented organic matter (150 kg), mineral framework (250 kg), and garden soil (450 kg) were mixed, and then microbial inoculants (20 kg) and trehalose activator (5 kg) were added. The mixture was piled up for activation, covered with a shade net, and turned over once a day for 7 days to obtain the artificial soil.

[0129] Step 6) Soil preparation: Test microbial activity (FDA hydrolysis rate >5μg / g·h), adjust pH to 6.5-7.0 (using dolomite powder / quicklime), add the above slow-release fertilizer granules (10kg) and LDHs carbon fixation agent (5kg), and finally control the moisture content to 25%-30%, then package and store.

[0130] Comparative Example 1

[0131] Compared with Example 1, in step one of Example 1, corn stalks (300kg), garden waste (250kg), chicken manure (250kg), and milkvetch (200kg) are crushed and mixed. After mixing, the materials are subjected to conventional fermentation with forced ventilation for 10 minutes per hour. The pile is turned over once a day, and the fermentation time is 30 days. The remaining steps are the same as in Example 1.

[0132] Comparative Example 2

[0133] Compared to Example 1, in step two of this example, no mineral-biochar framework is constructed; that is, the ore powder is not activated, and after being added to the base soil and mixed with washed sand, it is not ball-milled. Simultaneously, the rice husk biochar is not modified; it is added to the mixed ore powder and sand mixture. All other steps are the same as in Example 1.

[0134] Comparative Example 3

[0135] Compared to Example 1, in this example, step four) omits propagation and encapsulation; instead, the inoculum is directly mixed with fermentation organic matter, mineral framework, garden soil, and trehalose activator. The remaining steps are the same as in Example 1. The absence of propagation and encapsulation results in a lack of sustained-release carrier and energy supply for the inoculum, affecting its biological activity.

[0136] Test case

[0137] Performance tests were conducted on each embodiment and comparative example, and the results are as follows:

[0138] Table 1 Soil properties of examples and comparative examples

[0139]

[0140] The artificial soils prepared in each embodiment and comparative example were placed in a cool, indoor environment for 30 days before the aforementioned properties were tested. This facilitated a better comparison of differences in artificial soil nutrients, structural stability, and microbial activity. During the placement period, the soil was periodically watered to maintain a moisture content of approximately 50%, minimizing the impact of moisture loss on microbial activity.

[0141] A comparison of Example 1 with Comparative Examples 1-3 shows that optimizing the fermentation process, constructing a mineral-biochar framework, and encapsulating microorganisms can increase organic matter content, improve soil structure, and increase microbial biomass and activity.

[0142] A comparison of Example 1 with Examples 2-3 shows that adding nano-kaolin and biochar-mineral micro-aggregates in the later stage of the second-stage fermentation has a certain effect on alleviating the degradation of organic matter in the soil.

[0143] Test case

[0144] A planting experiment of Chinese cabbage (Kuai Cai No. 3) was conducted using the artificial soil from Example 1 of this invention and soil collected from vegetable gardens and woodlands. The results are as follows:

[0145] Plant rooting rate test method: The plant rooting rate is defined as the proportion of seeds that germinate. Specifically, after sowing Chinese cabbage seeds for 7 days, the ratio of the number of germinated seeds to the total number of seeds sown is measured and expressed as a percentage.

[0146] The method for testing the fresh weight of plants is as follows: The fresh weight of plants is expressed as the weight of the above-ground parts of freshly harvested plants. Specifically, 30 days after planting, the above-ground parts of the plants are cut off with scissors at a distance of 1 cm from the ground. All surviving bok choy are cut off and collected. The cut bok choy are rinsed with water to remove surface dust to ensure the reliability of the results. Then, the surface water is absorbed with filter paper, and the total mass of the harvested bok choy is weighed.

[0147] The experiment was conducted in three 110cm × 110cm planting trays for Sedum lineare, with artificial soil, garden soil, and woodland soil respectively, each 5cm thick. After soil collection, the moisture content was measured, and a final moisture content of 70% was used as a control. The amount of water needed was calculated and added accordingly. Soaked bok choy seeds were then sown in the trays, with 200 seeds sown in each tray, ensuring even spacing between seeds. After sowing, each tray was covered with the corresponding one of the three soil types, with a covering thickness of 0.5cm. The experiment was conducted outdoors.

[0148] Table 2 Growth status of bok choy

[0149]

[0150] The results in Table 2 show that artificial soil has a higher seed germination rate than vegetable garden soil and woodland soil. The fresh weight data also shows that artificial soil significantly promotes crop growth.

[0151] In summary, the artificial soil of this invention combines soil, biology, and materials science, focusing on three key dimensions: cascade transformation of organic matter, precise construction of the mineral framework, and directional cultivation of microbial communities. Through the synergistic fermentation of multi-source organic waste, combined with nanoscale mineral activation and biochar modification technology, a multi-level porous structure resembling a "honeycomb" is constructed. At the same time, specific functional microbial communities are implanted, enabling the rapid establishment of a self-sustaining soil ecosystem while achieving high humus content, high structural stability, and high biological activity in the cultivated soil.

[0152] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing artificial soil, characterized in that, Includes the following steps: Step 1) Two-stage fermentation: Ferment the biomass raw material at 60-65°C and oxygen concentration >10% for 8-15 days; then, conduct closed anaerobic fermentation at 35-40°C for 20-30 days to obtain fermented organic matter. Step 2) Mix the mineral powder containing mineral nutrients with sand to obtain a mineral sand mixture; the particle size of the mineral powder is less than 100 nm. Step 3) Immerse the biochar in a magnesium ammonium phosphate solution, and use vacuum treatment to allow the magnesium ammonium phosphate solution to enter the pores of the biochar to obtain magnesium ammonium phosphate-loaded biochar; then calcine the magnesium ammonium phosphate-loaded biochar at 150-180℃ to obtain modified biochar; mix the mineral sand mixture and the modified biochar at a weight ratio of 30-50:5-8 to obtain a mineral-biochar framework; Step 4) After culturing the bacterial strains containing slow-growing soybean rhizobia, azospirobacter, Penicillium oxalate, Bacillus megaterium, Azotobacter chrysogenum, and Trichoderma viride, the strains are adsorbed onto the carrier to form microspheres with a diameter of 2-3 mm, thus obtaining the bacterial agent. Step 5) Mix fermented organic matter, mineral-biochar framework, garden soil and microbial agent, and add trehalose as an activator. Cultivate for 7 days under shaded and aerated conditions to obtain the artificial soil. The weight ratio of fermented organic matter, mineral-biochar framework, garden soil, and microbial agent is 15-25:25-35:45~55:2-5; Add carbon-calcium micro-aggregates to the artificial soil obtained in step five, with the addition amount being 2-4% of the weight of the artificial soil; wherein the carbon-calcium micro-aggregates are formed by mixing modified biochar and nano-calcium carbonate powder at a ratio of 2:1 and reacting them under humid conditions at 58-62°C for 18-30 hours.

2. The method for preparing artificial soil according to claim 1, characterized in that, The biomass raw material in step one) includes the following components by weight: 20-30 parts by weight of herbaceous straw, 15-25 parts by weight of woody materials, 25-35 parts by weight of poultry and livestock manure, and 10-20 parts by weight of leguminous green manure; In step one, the biomass raw materials are fermented at 60-65°C and with an oxygen concentration >10% for 8-15 days. During the fermentation process, the moisture content of the first stage of fermentation is controlled to be 55%-65%.

3. The method for preparing artificial soil according to claim 1, characterized in that, After 15-20 days of closed anaerobic fermentation, kaolin is added to the biomass raw material, and closed anaerobic fermentation continues for another 5-10 days.

4. The method for preparing artificial soil according to claim 1, characterized in that, The mineral nutrients include selenium, phosphorus, calcium, iron, copper, zinc, manganese, and magnesium. Step two) involves mixing ore powder containing selenium, phosphorus, calcium, iron, copper, zinc, manganese and magnesium elements with sand to obtain a mineral sand mixture; the ore powder has a particle size of less than 100 nm and the weight ratio of ore powder to sand is 50-80:300-500. The ore powder contains 10-15 mg / kg of selenium, 250-350 mg / kg of phosphorus, 75-125 g / kg of calcium, 25-75 mg / kg of iron, 5-15 mg / kg of copper, 5-15 mg / kg of zinc, 75-152 mg / kg of manganese, and 25-75 g / kg of magnesium.

5. The method for preparing artificial soil according to claim 1, characterized in that, The biochar is at least one of rice husk biochar, corn cob biochar, and coconut shell biochar, with a specific surface area >300 m². 2 / g.

6. The method for preparing artificial soil according to claim 1, characterized in that, In step three), the biochar is immersed in a saturated magnesium ammonium phosphate solution, and the pressure is evacuated to -0.8 to -0.5 MPa and then restored to normal pressure for three cycles to ensure that the solution fully enters the pores of the biochar.

7. The method for preparing artificial soil according to claim 1, characterized in that, The preparation method further includes adding 0.3-0.8% of magnesium aluminum carbonate layered double hydroxide to the artificial soil obtained in step five).

8. The method for preparing artificial soil according to claim 1, characterized in that, The preparation method further includes: adding slow-release fertilizer to the artificial soil obtained in step five); The slow-release fertilizer includes a fertilizer core; The fertilizer core is covered by an inner coating layer, which includes phosphogypsum and humic acid. The outer side of the inner coating layer is covered by an outer coating layer, which includes dolomite powder and quicklime.

9. Artificial soil obtained by the method for preparing artificial soil according to any one of claims 1 to 8.

Images