Preparation method of artificial soil

Abstract

The invention belongs to the technical field of agriculture, 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 complex microbial inoculant, soil activation and the like. According to the invention, by systematically simulating a natural soil forming mechanism, combining soil, biology and material science, and surrounding three key dimensions of organic matter gradient conversion, mineral skeleton precision construction and microbial community cultivation, synergistic aerobic fermentation of multi-source organic wastes is improved; according to the method, a nano-scale mineral activation and biochar modification technology is developed to construct a honeycomb-like multi-stage pore structure, and meanwhile, a specific functional microbial community is implanted, so that high humus, high structural stability and high biological activity of the cultivated soil are achieved while rapid establishment of a soil self-sustaining ecosystem is realized.

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: A preparation method of artificial soil, comprising the following steps: Step one) Two-stage fermentation: fermenting biomass raw materials 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; Step two) mixing mineral powder containing mineral nutrient elements with sandy soil to obtain a mineral-sandy soil mixture; the particle size of the mineral powder is less than 100 nm; 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; Step four) after the culture of the strains including Bradyrhizobium japonicum, Azotobacter, Penicillium oxalicum, Bacillus megaterium, Azotobacter chroococcum and Trichoderma viride, the strains are adsorbed to the carrier to form microspheres with a diameter of 2-3 mm, and a microbial inoculum is obtained; Step five) the fermented organic matter, the mineral-biochar skeleton, the garden soil and the microbial inoculum are mixed, and trehalose is added as a stimulant, and the mixture is cultured for 7 days under light shielding and aeration conditions to obtain the artificial soil. The weight ratio of the fermented organic matter, the mineral-biochar skeleton, the garden soil and the microbial inoculum is 15-25:25-35:45-55:2-5.

[0005] In the present application, the traditional one-stage aerobic fermentation is changed to two-stage fermentation of "aerobic + anaerobic" by improving the multi-source organic matter fermentation method, so that the amount of humic acid substances is increased by adding an anaerobic stage. Humic acid substances are key cementing substances for the formation of soil aggregates, and the proportion of water-stable aggregates in the fermentation product is also greatly increased.

[0006] In the present application, the mineral-biochar skeleton is constructed to form a honeycomb structure, which supports soil particles through a rigid skeleton to promote the formation of stable aggregates. The abundant pore structure of the skeleton directly improves the aeration and water permeability of the soil. Even under high organic matter content, the root soil is not easy to block. The surface of the biochar and the mineral components can adsorb nutrients, delay decomposition and release rate, and achieve sustainable and balanced supply of nutrients.

[0007] In the present application, beneficial microbial species are introduced, and the survival time and colonization rate of the bacteria are improved through carrier adsorption, microbial inoculum microsphere preparation and nutrient supply.

[0008] Optionally, 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 material, 25-35 parts by weight of poultry manure, and 10-20 parts by weight of leguminous green manure; Preferably, the particle size of the herbaceous straw is 5-10 mm, the particle size of the woody material is 3-5 mm, the particle size of the poultry manure is less than 10 mm, and the particle size of the leguminous green manure is 5-10 mm. Preferably, the moisture content of the biomass raw material is controlled to be 55%-65% during the fermentation process of 8-15 days at 60-65°C and an oxygen concentration of >10% in step one).

[0009] Preferably, the herbaceous straw is corn straw, the woody material is garden waste, the poultry manure is chicken manure, and the leguminous green manure is Astragalus sinicus.

[0010] Optionally, after the closed anaerobic fermentation for 15-20 days, kaolin is added to the biomass raw material, and the closed anaerobic fermentation is continued for 5-10 days. Preferably, the amount of kaolin added is 1%.

[0011] Optionally, in step two, the ore powder containing selenium, phosphorus, calcium, iron, copper, zinc, manganese and magnesium is mixed with sand to obtain a mineral-sand mixture; the particle size of the ore powder is less than 100 nm, and the weight ratio of the ore powder to the sand is 50-80:300-500; The content of selenium in the ore powder is 10-15 mg / kg, the content of phosphorus is 250-350 mg / kg, the content of calcium is 75-125 g / kg, the content of iron is 25-75 mg / kg, the content of copper is 5-15 mg / kg, the content of zinc is 5-15 mg / kg, the content of manganese is 75-152 mg / kg, and the content of magnesium is 25-75 g / kg.

[0012] Optionally, the biochar is at least one of rice husk biochar, corn cob biochar and coconut shell biochar, and the specific surface area is greater than 300 m 2 / g.

[0013] Optionally, in step three, the biochar is immersed in a saturated ammonium magnesium phosphate solution, vacuumed to-0.8 to-0.5 MPa, and then restored to atmospheric pressure for 3 cycles to make the solution fully enter the pores of the biochar.

[0014] Optionally, carbon-calcium micro-aggregates are added to the artificial soil obtained in step five, and the addition amount is 2-4% of the weight of the artificial soil; wherein the carbon-calcium micro-aggregates are obtained by mixing modified biochar and nano calcium carbonate powder at a ratio of 2:1, and then reacting under humid conditions at 58-62°C for 18-30 hours to form carbon-calcium micro-aggregates.

[0015] Optionally, 0.3-0.8% of magnesium aluminum carbonate layered double hydroxide is added to the artificial soil obtained in step five.

[0016] Optionally, a slow-release fertilizer is added to the artificial soil obtained in step five. The slow-release fertilizer comprises a fertilizer core. The outer side of the fertilizer core is covered with an inner coating layer, and the inner coating layer comprises phosphorite and humic acid. The outer side of the inner coating layer is covered with an outer coating layer, and the outer coating layer comprises dolomite powder and slaked lime.

[0017] The technical scheme has the following advantages: The technical scheme aims to simulate the natural soil formation mechanism, combine modern soil biology and material science innovation, and efficiently cultivate excellent soil under controllable conditions.

[0018] Different from the single fermentation mode of traditional compost, the scheme proposes a two-stage fermentation mode of ''high-temperature aerobic + medium-temperature anaerobic'', combined with humic acid-montmorillonite accelerator, which greatly improves the HA / FA ratio and increases the generation rate of water-stable aggregate, breaking the bottleneck of poor structural stability of traditional compost.

[0019] In the present application, a nano-mineral and biochar composite skeleton system is proposed, which realizes the micropore synergy of large, medium and small pores, simulates the ''honeycomb'' structure, ensures the air permeability and maintains the high water holding capacity, and solves the problems of easy compaction and poor pore structure of traditional artificial soil. At the same time, the humic acid-mineral coordination bond can also enhance the stability of the aggregate, and the loss rate of organic matter under rainstorm scouring is low.

[0020] Unlike the traditional method of simply relying on mineral nutrient addition for soil cultivation, the present scheme constructs a ''organic matter-mineral-microorganism'' synergistic system, and performs three-level inoculation of functional microorganisms, activates the nutrient cycle and disease resistance mechanism through specific microbial community combination, and realizes the improvement of ''soil vitality''. At the same time, the three-level microbial community system has strong self-maintenance ability and does not need to supplement bacteria in the short term.

[0021] In order to simulate the nutrient supply rhythm of natural soil, the core-shell structure slow-release fertilizer of the present scheme is designed, which is different from the direct addition of traditional fertilizer. The fertility of the present scheme is not easy to lose, and the fertility supply is more durable.

[0022] The soil prepared by the present scheme has a larger bulk density due to the addition of a large amount of sandy soil, and can be directly planted with plants. Natural high-quality soil such as peat soil has high organic matter content, but the bulk density is low, and direct planting of plants is prone to lodging, and the root adhesion is low; the soil of the present application has high root adhesion and is not prone to lodging, and has high organic matter and high nutrients while considering the structural stability, which is superior to natural high-quality soil such as peat soil. DETAILED DESCRIPTION

[0023] The various illustrative embodiments of the present application will now be described in detail in connection with the accompanying drawings. This description is not intended to be a limitation on the application, but rather a description of certain aspects, features, and embodiments of the application. It is understood that the scope of the application is not limited to the aspects, features, and embodiments described herein, but include all aspects, features and embodiments within the scope of the appended claims.

[0024] In addition, for the numerical range in the present application, it is understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intermediate value in the stated range, is also included within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0025] All of the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined herein. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described herein.

[0026] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having" or variants thereof are open-ended, and specifically mean including, but not limited to.

[0027] The present application provides an artificial soil cultivation technology, which aims to simulate the natural soil formation mechanism systematically, combine soil, biology, material science, focus on three key dimensions of organic matter gradient transformation, mineral framework precise construction and microbial community directional cultivation, construct a multi-level pore structure similar to "honeycomb" through the synergistic fermentation of multi-source organic waste (straw, manure, etc.), combined with nanoscale mineral activation and biochar modification technology; At the same time, implant specific functional microbial community, realize the rapid establishment of soil self-sustaining ecosystem, and achieve the cultivation of soil with high humus, high structural stability and high biological activity. The present application specifically comprises the following steps: Step one) two-stage fermentation: fermenting biomass raw materials at 60-65°C and oxygen concentration> 10% for 8-15 days; then closed anaerobic fermentation at 35-40°C for 20-30 days to obtain fermented organic matter; Step two) mix mineral stone powder containing mineral nutrients with sandy soil to obtain a mineral-sandy soil mixture; the particle size of the mineral stone powder is less than 100 nm; Step three) immerse biochar in ammonium magnesium phosphate solution, and vacuum treat to make the ammonium magnesium phosphate solution enter the pores of the biochar to obtain ammonium magnesium phosphate loaded biochar; then calcine the ammonium magnesium phosphate loaded biochar to obtain modified biochar; mix the mineral-sandy soil mixture and the modified biochar to obtain a mineral-biochar framework; Step four) culture the strains containing Bradyrhizobium japonicum, Azospirillum brasilense, Penicillium oxalicum, Bacillus megaterium, Azotobacter chroococcum and Trichoderma viride, and then adsorb them onto a carrier to prepare microspheres with a diameter of 2-3mm to obtain a microbial agent; Step five) mix the fermented organic matter, the mineral-biochar framework, the field soil and the microbial agent, and add trehalose as a stimulant, and culture under light-shielded and aerated conditions for 7 days to obtain the artificial soil.

[0028] Further, the two-stage fermentation in step one) specifically comprises: One-stage fermentation (temperature control and oxygen consumption stage): The mixture is maintained at 60-65°C for 8-15 days, using a forced ventilation system (10 minutes of ventilation 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 of >10%, which can ensure effective degradation of lignocellulose without mold growth.

[0029] Fermentation raw material ratio (dry weight basis): Herbaceous straw, 30%, particle size 3-5 mm, providing readily available carbon source; Woody material, 25%, 3-5 mm, long-term carbon source, maintaining structure; Poultry manure, 25%, ≤2 mm, nitrogen source and microbial strains; Leguminous green manure, 20%, 5-10 mm, biological nitrogen fixation, and mineral activation.

[0030] Two-stage fermentation (anaerobic humification stage): After cooling to 35-40°C, the mixture is transferred to a sealed fermentation tank and humification accelerators (fulvic acid 0.1%, montmorillonite powder 0.5%, both based on the dry weight of the raw materials) are added for 20 days of anaerobic fermentation. The humification coefficient (HA / FA) in this stage is increased to 1.8-2.0, generating a large amount of humic acid substances, which are key cementing materials for the formation of soil aggregates and carbon sequestration. The final product has an organic matter content of more than 65% and a water-stable aggregate content of more than 50%.

[0031] The above precise ratio and two-stage fermentation process are one of the core innovations of the present application. Unlike the single fermentation mode of traditional composting, this technology uses a phased control strategy to maximize organic matter conversion efficiency and humus yield.

[0032] Further, the method in step two) includes: ball milling selenium ore powder (providing plant-available selenium elements), phosphorus ore powder (slow-release phosphorus source), calcium ore powder (promoting aggregate formation), iron ore powder (participating in redox reactions), and auxiliary trace element combinations (including Cu, Zn, Mn, and Mg ore powders) to a particle size of <100 nm and a specific surface area of 200-400 m 2 / g, significantly improving element availability. Then, the milled ore powder is mixed with sandy soil at a weight ratio of 50-80:300-500. The mixture is mixed in a mixer for 30 minutes at 45 r / min to ensure uniform dispersion.

[0033] The sandy soil is a soil with a sand particle (particle size 1-0.05 mm) content of more than 50%, and washed sand is preferably used.

[0034] The content of selenium in the ore powder is 10-15 mg / kg, the content of phosphorus is 250-350 mg / kg, the content of calcium is 75-125 g / kg, the content of iron is 25-75 mg / kg, the content of copper is 5-15 mg / kg, the content of zinc is 5-15 mg / kg, the content of manganese is 75-152 mg / kg, and the content of magnesium is 25-75 g / kg.

[0035] Further, the step three) comprises: Modified biochar preparation: select rice husk, corn cob, coconut shell biochar (specific surface area > 300 m 2 / g) and other materials as base material, and use ammonium magnesium phosphate loading process to enhance its nutrient retention capacity.

[0036] The biochar is immersed in a saturated ammonium magnesium phosphate solution (concentration 20%), vacuum pressurized (-0.8 to -0.5 MPa) for 3 times, so that the solution fully enters the micropores, and is solidified at 150-180°C to form a microporous slow-release structure. After modification, the cation exchange capacity (CEC) of the biochar is increased to 15-20 cmol / kg, and the anion exchange capacity (AEC) is 5-8 cmol / kg, becoming a high-efficiency "nutrient bank". In the nano-mineral and biochar composite skeleton system, the addition ratio of nano-mineral and modified biochar is 30-50:5-8, and the mineral-biochar skeleton is formed by mixing uniformly.

[0037] The above-mentioned nano-mineral and biochar composite skeleton system accurately simulates the "honeycomb-like" structure of black calcareous soil, solving the problems of easy compaction and poor pore structure of traditional artificial soil. The cultivated soil has suitable voids, and ideal pore distribution is achieved through hierarchical construction: large pores (> 30 μm, air permeation and water permeation) are provided by straw fragments (3-10 mm) and biochar (2-4 mm); medium pores (0.2-30 μm, water retention and root growth) rely on organic-mineral composite aggregates; micropores (< 0.2 μm, adsorption of nutrients) are contributed by the surface of nano-minerals and the micropores of biochar. By controlling the addition amount of different components, the proportion of each substance in large voids, medium voids and micro voids is controlled, so that the total porosity of the final product is > 55%, the air permeation pore / water retention pore ratio is approximately 1:2, and the structure is close to ideal black calcareous soil.

[0038] The three-stage inoculation of functional microorganisms in the step four) is the core of the present scheme to realize "soil vitality", and activates the nutrient circulation and disease resistance mechanism through specific flora combination, which specifically comprises the following steps: Compound microbial agent formula: slow-growing soybean rhizobium (Bradyrhizobium japonicum) + nitrogen-fixing spirillum (Azospirillum brasilense), inoculation amount 10 6CFU / g; phosphorus solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculation amount 10 5 CFU / g; carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculation amount 10 4 CFU / g.

[0039] Expansion and embedding: each strain is expanded to the target concentration in a special culture medium (such as nitrogen-free medium for azotobacter), mixed in proportion, adsorbed on calcium alginate gel carrier (containing 5% humic acid), granulated into microbial agent microspheres with a diameter of 2-3 mm, and stored at low temperature after drying.

[0040] The step five) specifically includes: The weight ratio of fermented organic matter, mineral-biochar skeleton, field soil, and microbial agent is 15-25:25-35:45-55:2-5, the moisture content is adjusted to 40%, and 0.5% trehalose stimulant is added. Under light shielding conditions, cultivate for 7 days, turn over and aerate daily to promote microbial colonization, and detect microbial activity (FDA hydrolysis rate > 5 μg / g·h) before use. This method makes the soil microbial biomass far exceed that of conventional farmland soil, and the functional diversity index is significantly improved.

[0041] The field soil is taken from farmland or vegetable field, and its basic physicochemical properties include: bulk density 1.1-1.3 (g / cm 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, and cation exchange capacity (CEC) 10-20 cmol / kg.

[0042] In some specific embodiments, to strengthen carbon sequestration and nutrient release capacity, the present scheme proposes a humus-nanomineral covalent bonding technology: Humus locking: add nano-kaolin (addition amount 1%) in the later stage of two-stage fermentation, and the stable coordination bond complex Al-OH / COOH is formed between the surface aluminum hydroxyl (Al-OH) and the humic acid carboxyl (-COOH), which greatly improves the anti-degradation ability of humic acid.

[0043] Biochar-mineral micro-agglomerate preparation and addition: Add carbon-calcium micro-agglomerates in artificial soil, the amount of addition is 2-4% of the weight of the soil; wherein the carbon-calcium micro-agglomerates are formed by mixing modified biochar and nano calcium carbonate powder at a ratio of 2:1 under humid conditions at 60°C for 24 hours (size 0.5-2mm). This structure reduces the mineralization rate of organic carbon and prolongs the half-life. The amount of addition is 2-4% of the weight of the soil.

[0044] Layered double hydroxide addition: Add 0.5% of magnesium aluminum carbonate type layered double hydroxide in the soil product, which can fix HCO3 - in the soil solution, gradually converted to CO3 2- , achieving inorganic carbon sequestration and additional carbon sink capacity.

[0045] In some specific embodiments, in order to simulate the nutrient supply rhythm of natural soil, the scheme adds core-shell structure slow-release fertilizer in artificial soil.

[0046] Soil slow-release fertilizer preparation: Core preparation, mixed according to the ratio of N:P2O5:K2O=12:18:10, wherein: Nitrogen source: matured manure (N content 3.5%) + urea (30%); phosphorus source: nano phosphate ore powder (total phosphorus > 28%) + ammonium magnesium phosphate (10%); potassium source: potassium feldspar nano powder (K2O > 9%) + potassium sulfate (20%); and adding chelated trace elements (Fe, Zn, B, etc.) Coating process, first granulate the core into particles with a diameter of 3-5mm, then coat it in two times, wherein: The inner coating layer includes phosphogypsum (addition amount 10%) and humic acid (5%), forming an ion exchange layer; The outer coating layer includes dolomite powder (particle size 0.1mm, addition amount 15%) and slaked lime (5%), used to provide pH buffer.

[0047] Finally forming particles with a diameter of 6-8mm. This fertilizer shows three-stage release in soil: the outer layer dissolves within 24 hours to adjust pH; the inner layer gradually releases NPK within 7-14 days; the core maintains slow dissolution for 1-2 months. Compared with ordinary chemical fertilizers, the loss rate of nitrogen and phosphorus is greatly reduced.

[0048] Mix the slow-release particles with soil at a mass ratio of 1:50-200.

[0049] The above artificial soil can be used as follows: Direct use: lay a thickness of ≥30cm, matched with drip irrigation system. Or land degradation improvement: apply 5-20 tons per mu, deep plough 25cm, and then plant.

[0050] Example 1 Step one) Multiple source organic matter step fermentation Corn straw (300 kg), garden waste (250 kg), chicken manure (250 kg), and Chinese milk vetch (200 kg) were crushed and mixed into a one-stage fermentation: a sampling tank fermentation system with temperature control at 63 ± 2°C, with one-time turning per day for 10 days, with the addition of humification accelerators (fulvic acid 0.35 kg, montmorillonite powder 1.75 kg), and then transferred to a closed fermentation tank for two-stage fermentation, with the two-stage fermentation maintained at 38 ± 2°C, with one-time turning per week for 20 days. The detection indexes were: C / N < 20, HA / FA > 1.8, and water stable aggregate > 50%, indicating that the fermentation was complete.

[0051] Step two) Preparation of nano-minerals and activation Nano-mineral powder (total amount 80 kg) and washed sandy soil (300 kg) were pre-mixed according to the formula to form a sandy soil-mineral mixture. The nano-mineral powder had a particle size < 100 nm, a specific surface area of 300 m 2 / g, and significantly improved element availability. After addition, the mixture was mixed in a mixer for 30 minutes at 45 r / min to ensure uniform dispersion.

[0052] The nano-mineral powder contained the following mass fractions of nutritional elements: selenium: 12 mg / kg; phosphorus: 300 mg / kg; calcium: 100 g / kg; iron: 50 mg / kg; copper: 10 mg / kg; zinc: 10 mg / kg; manganese: 100 mg / kg; and magnesium: 50 g / kg.

[0053] Step three) Preparation of mineral-biochar framework: Modified biochar preparation: rice husk biochar (specific surface area > 300 m 2 / g) was selected as the base material, and a magnesium ammonium phosphate loading process was used to enhance its nutrient retention capacity. 60 kg of biochar was immersed in a 20% saturated ammonium magnesium phosphate solution, vacuum pressurized (-0.8 MPa) for 3 cycles to allow the solution to fully enter the micropores, and then solidified by low-temperature calcination at 150°C to form a microporous slow-release structure.

[0054] Mineral-biochar framework preparation: the sandy soil-mineral mixture and modified biochar were mixed using a double-shaft mixer to obtain the mineral-biochar framework.

[0055] Step four) Preparation of composite microbial agent: Inoculation and culture: Bradyrhizobium japonicum + Azospirillum brasilense, inoculation amount 10 6CFU / g; phosphorus release layer: Penicillium oxalicum + Bacillus megaterium, inoculation amount 10 5 CFU / g; carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculation amount 10 4 CFU / g.

[0056] Expansion and embedding: each strain is expanded to the target concentration in a special medium (such as nitrogen-free medium for azotobacter), mixed in proportion, adsorbed on calcium alginate gel carrier (containing 5% humic acid), and then granulated into microbial agent microspheres with a diameter of 3 mm, and stored after low-temperature drying.

[0057] Step five) soil activation: Mix the fermented organic matter (200 kg), mineral framework (300 kg), and garden soil (475 kg), then add microbial agent microspheres (20 kg) and trehalose stimulant (5 kg). Activate the pile, cover it with a shading net, turn it over once a day for 7 days. The artificial soil is obtained.

[0058] Step six) soil deployment: Slow-release fertilizer granule preparation: use decomposed chicken manure and urea as nitrogen sources, use nano phosphate ore powder and ammonium magnesium phosphate as phosphorus sources, use potassium feldspar nano powder and potassium sulfate as potassium sources, control the N:P2O5:K2O ratio to be 12:18:10, mix and granulate to form 3-5 mm diameter granules, then coat them in two layers, with the inner coating layer being composed of phosphogypsum (10% addition) + humic acid (5%), and the outer coating layer being composed of dolomite powder (0.1 mm particle size, 15% addition) + slaked lime (5%).

[0059] Soil deployment includes: detecting microbial activity (FDA hydrolysis rate > 5 μg / g·h), adjusting the pH to 6.5-7.0 (using dolomite powder / slaked lime), adding slow-release fertilizer granules (10 kg) and LDHs carbon sequestration agent (5 kg), and finally controlling the moisture content to be 25%-30%, and packaging for storage.

[0060] Example 2 Compared with Example 1, after 15-20 days of closed anaerobic fermentation in step one), kaolin clay (1% addition) is added to the biomass raw material, and the closed anaerobic fermentation is continued for 5-10 days, so that the aluminum hydroxyl group (Al-OH) on the surface of the kaolin clay forms a stable coordination bond complex Al-OH / COOH with the carboxyl group (-COOH) of humic acid. The remaining steps are the same as in Example 1.

[0061] Example 3 Compared with Example 1, in this example, biochar-mineral microaggregates were added in step five) soil preparation, and the addition amount was 3% of the weight of the soil. The above biochar-mineral microaggregates were formed by mixing modified biochar and nano calcium carbonate powder at a ratio of 2:1, reacting for 24 hours under humid conditions at 60°C, to form carbon-calcium microaggregates. Biochar-mineral microaggregates (size 0.5-2mm) were formed. The remaining steps were the same as in Example 1.

[0062] Example 4 Step one) two-stage fermentation: corn straw (300 kg), garden waste (250 kg), chicken manure (250 kg), and Chinese milk vetch (200 kg) were crushed and mixed into a one-stage fermentation: sampling tank fermentation system, and fermented under the conditions of 60°C and oxygen concentration >10% for 15 days; then anaerobically fermented under the conditions of 35-40°C for 20-30 days to obtain fermented organic matter; Step two) The nano mineral powder (total amount 80 kg) and washed sandy soil (500 kg) were pre-mixed according to the formula to form a sandy soil-mineral mixture. The nano mineral powder has a particle size of <100 nm, a specific surface area of 300 m 2 / g, and significantly improves the availability of elements. After adding, the mixer was mixed at 45 r / min for 30 minutes to ensure uniform dispersion.

[0063] The nano mineral powder contains the following mass fractions of nutritional elements: selenium: 12 mg / kg; phosphorus: 300 mg / kg; calcium: 100 g / kg; iron: 50 mg / kg; copper: 10 mg / kg; zinc: 10 mg / kg; manganese: 100 mg / kg; and magnesium: 50 g / kg.

[0064] Step three) mineral-biochar skeleton preparation: modified biochar preparation: corn cob biochar (specific surface area >300 m 2 / g) was selected as the base material, and a magnesium ammonium phosphate loading process was used to enhance its nutrient retention capacity. 60 kg of biochar was immersed in a 20% saturated ammonium magnesium phosphate solution, vacuum pressurized (-0.8 MPa) for 3 cycles, and the solution was fully introduced into the micropores, and 150°C low-temperature calcination was performed to form a microporous slow-release structure.

[0065] Mineral-biochar skeleton preparation: the sandy soil-mineral mixture and modified biochar were mixed with a double-shaft mixer to obtain a mineral-biochar skeleton.

[0066] Step four) preparation of a composite microbial agent: 1. Inoculation and culture, Bradyrhizobium japonicum + Azospirillum brasilense, inoculation amount 10 6CFU / g; phosphorus solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculation amount 10 5 CFU / g; carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculation amount 10 4 CFU / g.

[0067] 2. Expansion and embedding, each strain is expanded to the target concentration in a special medium (such as nitrogen-free medium for azotobacter), mixed in proportion, adsorbed on calcium alginate gel carrier (containing 5% humic acid), and then granulated into microbial agent microspheres with a diameter of 3 mm, and stored after low-temperature drying.

[0068] Step five) soil activation: mix fermented organic matter (250 kg), mineral framework (350 kg), and garden soil (550 kg), then add microbial agent microspheres (20 kg) and trehalose stimulant (5 kg). Activate by stacking, cover with shading net, turn over once a day for 7 days. Obtain the artificial soil.

[0069] Step six) soil deployment: detect microbial activity (FDA hydrolysis rate > 5 μg / g·h), adjust pH to 6.5-7.0 (use dolomite powder / limewater), add slow-release fertilizer particles (10 kg) and LDHs carbon sequestration agent (5 kg) as described above, and finally control the moisture content to 25%-30%, package and store.

[0070] Example 5 Step one) two-stage fermentation: crush and mix corn straw (300 kg), garden waste (250 kg), chicken manure (250 kg), and Chinese milk vetch (200 kg) into a one-stage fermentation: sample tank fermentation system, ferment at 65°C and oxygen concentration > 10% for 8 days; then anaerobically ferment at 35-40°C for 20-30 days to obtain fermented organic matter; Step two) pre-mix the nano-mineral powder (total amount 50 kg) and washed sandy soil (300 kg) according to the formula to form a sandy soil-mineral mixture. The nano-mineral powder is ball-milled to a particle size < 100 nm and a specific surface area of 300 m 2 / g, significantly improving element availability. After adding, mix in a mixer at 45 r / min for 30 minutes to ensure uniform dispersion.

[0071] The nano-ore powder contains the following mass fractions of nutritional elements: selenium: 12 mg / kg; phosphorus: 300 mg / kg; calcium: 100 g / kg; iron: 50 mg / kg; copper: 10 mg / kg; zinc: 10 mg / kg; manganese: 100 mg / kg; and magnesium: 50 g / kg.

[0072] Step three) mineral-biochar skeleton preparation: modified biochar preparation: coconut shell biochar (specific surface area > 300 m 2 / g) is selected as a base material, and a magnesium ammonium phosphate loading process is used to enhance its nutrient retention capacity. 60 kg of biochar is immersed in a 20% saturated ammonium magnesium phosphate solution, vacuum pressurized (-0.8 MPa) for 3 cycles, so that the solution fully enters the micropores, and is solidified by low-temperature calcination at 150°C to form a microporous slow-release structure.

[0073] Mineral-biochar skeleton preparation: the sand-mineral mixture and the modified biochar described above are mixed using a double-shaft mixer to obtain a mineral-biochar skeleton.

[0074] Step four) preparation of a composite microbial agent 1. inoculation and culture, Bradyrhizobium japonicum + Azospirillum brasilense, inoculation amount 10 6 CFU / g; phosphorus solubilizing layer: Penicillium oxalicum + Bacillus megaterium, inoculation amount 10 5 CFU / g; carbon conversion layer: Azotobacter chroococcum + Trichoderma viride, inoculation amount 10 4 CFU / g.

[0075] 2. expansion and embedding, each strain is expanded to the target concentration in a special culture medium (such as nitrogen-free medium for nitrogen-fixing bacteria), mixed in proportion, and then adsorbed on calcium alginate gel carriers (containing 5% humic acid) to form microbial agent microspheres with a diameter of 3 mm, which are then dried and stored at low temperature.

[0076] Step five) soil activation The fermented organic matter (150 kg), mineral skeleton (250 kg), and garden soil (450 kg) are mixed, and then the microbial agent microspheres (20 kg) and trehalose stimulants (5 kg) are added. The mixture is activated by stacking and covering with a shading net, and is turned over once a day for 7 days. The artificial soil is obtained.

[0077] Step six) soil deployment: detect microbial activity (FDA hydrolysis rate > 5 pg / g h), adjust pH to 6.5-7.0 (with dolomite powder / limewater), add slow-release fertilizer particles (10 kg) and LDHs carbon sequestration agent (5 kg) as described above, and control the final moisture content at 25%-30%, package and store.

[0078] Comparative Example 1 Compared with Example 1, in Step one) of this example, corn straw (300 kg), garden waste (250 kg), chicken manure (250 kg), and Chinese milk vetch (200 kg) were crushed and mixed, and the mixed materials were then subjected to conventional fermentation. Forced aeration was performed for 10 minutes per hour, and the heap was turned over once a day. The fermentation lasted for 30 days. The remaining steps were the same as in Example 1.

[0079] Comparative Example 2 Compared with Example 1, in Step two) of this example, the mineral-biochar skeleton was not constructed, i.e., the mineral powder was not subjected to activation treatment. The mineral powder was added to the base soil and mixed with washed sandy soil without ball milling treatment. The rice husk biochar was also not subjected to modification treatment, and was added to the mixture of the mineral powder and sandy soil. The remaining steps were the same as in Example 1.

[0080] Comparative Example 3 Compared with Example 1, in Step four) of this example, the propagation and embedding were not performed, and the strains were directly mixed with the fermented organic matter, the mineral skeleton, the field soil, and the trehalose activator in Step four). The remaining steps were the same as in Example 1. The lack of slow-release carriers and energy supply due to the absence of propagation and embedding affected the biological activity of the microbial agent.

[0081] Test Example The performance of each example and comparative example was tested, and the results are as follows: Table 1 Soil properties of examples and comparative examples

[0082] The artificial soil prepared in each example and comparative example was placed in an indoor cool place for 30 days before testing the above properties, so as to better compare the differences in nutrient content, structural stability, and microbial activity of the artificial soil. Water was sprayed on the soil regularly during the placement period to maintain a moisture content of about 50%, thereby reducing the impact of water reduction on microbial activity.

[0083] Comparing Example 1 with Comparative Examples 1-3, it can be seen that the optimization of the fermentation process, the construction of the mineral-biochar skeleton, and the embedding of the strains can improve the organic matter content, improve the soil structure, and increase the microbial biomass and activity.

[0084] Comparing example 1 with example 2-3 can see that adding nano-kaolin in the later stage of two-stage fermentation, and adding biochar-mineral micro-agglomerates, can alleviate the degradation of organic matter in the soil to a certain extent.

[0085] Test example The artificial soil in example 1 of the present application and the soil collected from the vegetable garden and the forest land are used to carry out a pakchoi (kuai vegetables No. 3) planting test. The results are as follows: The plant rooting rate test method: the plant rooting rate is defined as the ratio of seed germination, and the specific method is that after 7 days of sowing, the number of germination and the total number of sown seeds are measured, and the ratio is expressed in %.

[0086] The test method of the fresh weight of the plant: the weight of the aboveground part of the just harvested plant is used to represent the fresh weight of the plant, and the specific method is that after 30 days of planting, the aboveground part of the plant is cut off with scissors, the cutting position is 1 cm from the ground surface, all surviving pakchoi are cut off, all cut pakchoi are collected, surface dust is washed off with water to ensure the reliability of the results, then the surface water is absorbed with filter paper, and the total weight of the harvested pakchoi is weighed.

[0087] The test is carried out in a sedum lineare planting tray (110 cm x 110 cm), a total of 3 planting trays, artificial soil, vegetable garden soil and forest land soil are laid respectively, and the soil laying thickness is 5 cm. After the soil is taken back, the moisture content is first measured, and the final moisture content of the soil in the three trays is controlled to be 70%, the amount of water to be added is calculated and the water is sprinkled. After soaking, the seeds are sown into the soil, 200 seeds are sown in each tray, and the distance between the seeds is uniform. After sowing, each tray is covered with the corresponding three kinds of soil, and the covering thickness is 0.5 cm. The test is carried out outdoors.

[0088] Table 2: Growth of pakchoi

[0089] As can be seen from the results in table 2, the seed germination rate of the artificial soil is higher than that of the vegetable garden soil and the forest land soil, and the fresh weight shows that the artificial soil promotes the growth of crops very obviously.

[0090] In summary, the artificial soil of the present application combines soil, biology and material science, focuses on three key dimensions of organic matter cascade transformation, mineral framework precise construction and microbial community directional cultivation, constructs a multi-level pore structure similar to a "honeycomb" through the synergistic fermentation of multi-source organic waste, combines nano-scale mineral activation and biochar modification technology, implants specific functional microbial community, realizes the rapid establishment of soil self-sustaining ecosystem, and achieves the cultivation of soil with high humus, high structural stability and high biological activity.

[0091] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A method for producing an artificial soil, characterized by, The method comprises the following steps: 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; Step two) mixing ore powder containing mineral nutrients with sandy soil to obtain a mineral-sandy soil mixture; the particle size of the ore powder is less than 100 nm; Step three) immersing biochar in an ammonium magnesium phosphate solution, allowing the ammonium magnesium phosphate solution to enter the pores of the biochar through vacuum treatment to obtain ammonium magnesium phosphate-loaded biochar; then calcining the ammonium magnesium phosphate-loaded biochar 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; Step four) culturing strains containing Bradyrhizobium japonicum, Azotobacter, Penicillium oxalicum, Bacillus megaterium, Azotobacter chroococcum, and Trichoderma viride, and then adsorbing the strains onto a carrier to obtain microspheres with a diameter of 2-3 mm, thereby obtaining a microbial agent; Step five) mixing the fermented organic matter, the mineral-biochar skeleton, field soil, and the microbial agent, and adding trehalose as a stimulant, and then culturing under light-shielded and aerated conditions for 7 days to obtain the artificial soil. The weight ratio of the fermented organic matter, the mineral-biochar skeleton, the field soil, and the microbial agent is 15-25:25-35:45-55:2-5.

2. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. The biomass raw material in step one) comprises the following components by weight: 20-30 parts by weight of herbaceous straw, 15-25 parts by weight of woody material, 25-35 parts by weight of poultry manure, and 10-20 parts by weight of leguminous green manure; During the fermentation process in step one), the moisture content of the first-stage fermentation is controlled to be 55%-65% under the condition of fermenting the biomass raw material at 60-65°C and an oxygen concentration of >10% for 8-15 days.

3. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. After 15-20 days of closed anaerobic fermentation, kaolin is added to the biomass raw material, and the closed anaerobic fermentation is continued for 5-10 days.

4. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. Step two) mixing ore powder containing selenium, phosphorus, calcium, iron, copper, zinc, manganese, and magnesium with sandy soil to obtain a mineral-sandy soil mixture; the particle size of the ore powder is less than 100 nm, and the weight ratio of the ore powder to the sandy soil is 50-80:300-500; The content of selenium in the ore powder is 10-15 mg / kg, the content of phosphorus is 250-350 mg / kg, the content of calcium is 75-125 g / kg, the content of iron is 25-75 mg / kg, the content of copper is 5-15 mg / kg, the content of zinc is 5-15 mg / kg, the content of manganese is 75-152 mg / kg, and the content of magnesium is 25-75 g / kg.

5. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. The biochar is at least one of rice husk biochar, corn cob biochar, and coconut shell biochar, and has a specific surface area > 300 m 2 / g.

6. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. In step three), the biochar is immersed in a saturated ammonium magnesium phosphate solution, vacuumed to -0.8 to -0.5 MPa, and then restored to atmospheric pressure for 3 cycles to allow the solution to fully enter the pores of the biochar.

7. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. The preparation method further comprises: adding carbon-calcium micro-aggregates into the artificial soil obtained in step five), and the adding amount is 2-4% of the weight of the artificial soil; wherein the carbon-calcium micro-aggregates are obtained by mixing modified biochar and nano calcium carbonate powder at a ratio of 2:1, and then reacting under humid conditions at 58-62°C for 18-30 hours to form the carbon-calcium micro-aggregates.

8. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. The preparation method further comprises: adding 0.3-0.8% of magnesium-aluminum carbonate layered double hydroxide into the artificial soil obtained in step five).

9. The method of claim 1, wherein the artificial soil is prepared by mixing the clay, the organic matter, and the water. The preparation method further comprises: adding slow-release fertilizer into the artificial soil obtained in step five). The slow-release fertilizer comprises a fertilizer core. The outside of the fertilizer core is covered with an inner coating layer, and the inner coating layer comprises: phosphogypsum and humic acid. The outside of the inner coating layer is covered with an outer coating layer, and the outer coating layer comprises: dolomite powder and slaked lime.

10. Artificial soil obtained by the preparation method of the artificial soil according to any one of claims 1-9.

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