A plant cultivation substrate, and a method of preparing and using the same

Abstract

The present application belongs to the technical field of resource utilization of agricultural, forestry and animal husbandry wastes, and particularly relates to a plant cultivation substrate, a preparation method and application thereof. The method comprises the following steps: mixing and kneading solid precipitates at the bottom of a biogas slurry settling tank of a livestock and poultry farm, wood cellulose biological materials treated by dilute phosphoric acid solution, and mineral clay or farmland soil powder treated by magnesium oxide in proportion to form balls, and finally obtaining the plant cultivation substrate through a dark combustion reaction. The cultivation substrate prepared by the method has the advantages of long fertilizer effect and good fertilizer and moisture preservation effect, and can be used for cultivation of high-grade vegetables, medicinal materials, flowers, trees and fruit trees. Meanwhile, the method solves the harmless disposal of the solid precipitates at the bottom of the biogas slurry settling tank of the livestock and poultry farm, and achieves good social and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of agricultural, forestry and animal husbandry waste resource utilization technology, specifically relating to a plant cultivation substrate, its preparation method and application. Background Technology

[0002] With the rise of protected cultivation and the cultivation of special economic crops, the demand for cultivation substrates has increased significantly. Cultivation substrates refer to solid media that can replace soil to fix plant roots, absorb and retain nutrients and water, control the distribution of solid, liquid, and gas phases, and provide a habitat for microorganisms. Commercial cultivation media include porous, relatively stable organic or inorganic materials with certain mechanical strength and cation exchange capacity, such as peat, bark powder, perlite, and polyurethane foam.

[0003] To address the pollution problem caused by manure from intensive livestock and poultry farms, companies are generally required to construct biogas treatment facilities. The biogas slurry discharged annually must first undergo gravity settling in a sedimentation tank, resulting in a large amount of solid sediment at the bottom of the tank, which needs to be cleaned regularly. This type of sediment contains high levels of reducing substances, antibiotic residues, and heavy metal residues, and has low biodegradability, necessitating the discovery of better disposal and utilization methods.

[0004] Currently, composting is an effective way to utilize agricultural waste resources. However, the quality of compost products is low, and the benefits and utilization rates are poor. Therefore, there is an urgent need to find a method that can better address the pollution problem caused by livestock and poultry farm manure and produce a high-quality cultivation substrate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plant cultivation substrate, its preparation method, and its application. Specifically, the following technical solution is adopted:

[0006] In a first aspect, the present invention provides a method for preparing a plant cultivation substrate, comprising the following steps:

[0007] S1: Dry and crush the solid sediment at the bottom of the biogas slurry sedimentation tank in the livestock and poultry farm to 40-60 mesh to obtain the first matrix;

[0008] S2: Crush lignocellulosic biomass to 40-60 mesh, then spray it with a 5%-10% dilute phosphoric acid solution, mix and compact it for 24-48 hours to obtain the second matrix;

[0009] S3: Spray magnesium oxide emulsion onto mineral clay or cultivated soil powder that does not contain coarse sand, mix well, compact, seal and diffuse for 24-36 hours, then spread out to dry and crush through a 40-60 mesh sieve to obtain the third matrix.

[0010] S4: After mixing 4-5 parts of the first substrate obtained in step S1, 2-3 parts of the second substrate obtained in step S2 and 1-2 parts of the third substrate obtained in step S3, knead into balls with a diameter of 8-15 mm, dry and control the water content to be 10-12%, to obtain mixed balls of the first substrate, the second substrate and the third substrate;

[0011] S5: Put the mixed balls obtained in step S4 into a closed muffle furnace, heat the inner bore temperature to 105-110℃, at the same time open the air outlet and air inlet of the muffle furnace, keep for 10-15 min to remove excess water vapor, then close the air inlet and air outlet of the muffle furnace, and raise the temperature to 450℃, heat for 5-10 min, control the oxygen supply amount in the muffle furnace to be 30-60% of the oxygen required for complete combustion of organic matter in the mixed balls, and carry out dark combustion reaction for 1-5 h, to finally obtain a plant cultivation substrate.

[0012] In the above step: In step S1, the drying and crushing of the solid precipitate can increase its specific surface area and improve the reactivity of subsequent treatment, and the control in 40-60 mesh can prevent the particles from being too large to affect the uniformity of mixing, and also avoid the agglomeration of fine powder affecting the flowability;

[0013] In step S2, dilute phosphoric acid is added during pretreatment, which can dissolve part of cellulose and lignin and other components, reduce the coking temperature, improve the water absorption, and also create conditions for the formation of the subsequent embedded structure;

[0014] In step S3, the use of magnesium oxide can promote the conversion of ammonium dihydrogen phosphate in the solid precipitate at the bottom of the livestock and poultry farm biogas slurry sedimentation tank to struvite in clay or cultivated soil during heat treatment, and magnesium oxide can passivate heavy metal ions, reduce the inhibition of heavy metals on phosphorus conversion, and increase the release amount of available phosphorus in the substrate;

[0015] In step S4, the water content is controlled to be 10-12%, which helps to heat the substrate uniformly inside the muffle furnace during the heating process, and improves the embedded structure of the substrate components; In addition, the water content of 10-12% can ensure the regulating effect of water during heating, and also will not make the substrate ball volume too large to increase the heating difficulty, and too high water content will lead to too fast evaporation of water in the early stage of heating in the muffle furnace, uneven heating; while too low water content will make it difficult to form the embedded structure between the substrate components;

[0016] In step S5, the temperature is heated to 105-110℃, which sufficiently dries and preheats the substrate balls, prevents the balls from being broken due to too fast moisture evaporation caused by rapid temperature rise, and controls the oxygen supply in the muffle furnace to be 30-60% of the oxygen required for complete combustion of the organic matter in the mixed balls, which can ensure the smooth progress of the subsequent dark combustion reaction and avoid excessive oxygen supply, which can make the reaction too violent, reduce the yield and damage the product quality.

[0017] In the preparation method, the organic matter in the mixture of clay or cultivated soil, solid precipitate at the bottom of the biogas slurry settling tank in livestock and poultry farms and wood cellulose is carbonized and partially chemically combined with the clay to form a chemical bond, and the complex reaction of phosphate, ammonium ions and magnesium ions forms struvite. The addition of magnesium oxide in the clay or cultivated soil can promote the conversion of ammonium dihydrogen phosphate in the clay or cultivated soil during the heat treatment of the solid precipitate at the bottom of the biogas slurry settling tank in livestock and poultry farms, and the heavy metals are passivated. Moreover, the antibiotic residues, pathogenic bacteria, viruses and harmful ingredients are completely destroyed by high temperature. At the same time, the addition of phosphoric acid in the wood cellulose biomass can reduce the carbonization temperature and reduce the energy consumption. In addition, the present application solves the harmless disposal of the solid precipitate at the bottom of the biogas slurry settling tank in livestock and poultry farms, and obtains a new type of high-quality plant cultivation substrate, which has good social and economic benefits.

[0018] In the preparation method, the heat generated by the dark combustion of plant residues is used to kill pathogenic microorganisms and continuous cropping obstacles, promote the carbonization of plant residues and partially form a porous composite material with clay, which can achieve an immediate effect on the yield increase of plants, especially fruits and vegetables.

[0019] As a further preferred embodiment, the above-mentioned step S1 livestock and poultry farms include intensive chicken farms or intensive pig farms. The wood cellulose biomass in step S2 includes at least one of rice straw, wheat straw, corn stalks, bamboo chips, pine sawdust and chaff.

[0020] As a further preferred embodiment, the above-mentioned dilute phosphoric acid solution (the mass fraction of phosphoric acid is 5-10%) is used in an amount of 40-60% of the mass of the wood cellulose biomass. Too high a dosage of dilute phosphoric acid solution will cause excessive acidification of the cultivation substrate and high production cost, and too low a dosage will not effectively dissolve the cellulose and lignin in the wood cellulose biomass, which cannot effectively reduce the carbonization temperature.

[0021] For further preferred embodiments, the amount of the magnesium oxide emulsion sprayed in step S3 is 20% to 30% of the dry weight of the mineral clay or the cultivated soil powder without coarse sand. The ratio of magnesium oxide to water in the magnesium oxide emulsion is 1:4. If the amount of the magnesium oxide emulsion is too large, the soil will be alkalized, and if the amount of the magnesium oxide emulsion is too small, the struvite ligand will be insufficient during the sintering process of the substrate ball, resulting in the loss of nitrogen. If the ratio of magnesium oxide in the magnesium oxide emulsion is too high, the processing difficulty will be increased, and it is not conducive to uniform spraying in the substrate to be treated. If the ratio of magnesium oxide in the magnesium oxide emulsion is too low, excessive water will be introduced into the substrate, which is not conducive to subsequent processing.

[0022] As further preferred embodiments, the amount of oxygen supplied in the muffle furnace is 45% to 50% of the oxygen required for complete combustion of the organic matter in the mixed ball. If the amount of oxygen is less than this range, the dark combustion reaction will not be sufficient, and if the amount of oxygen is too high, the dark combustion reaction will be too intense, reducing the yield and damaging the product quality.

[0023] The second aspect of the present application also provides a plant cultivation substrate prepared by the above method, which can be applied to crop or plant cultivation. The crops or plants include high-grade vegetables, medicinal materials, flowers, fruit trees or forest trees.

[0024] The beneficial effects of the present application are: the present application innovatively uses the solid precipitate at the bottom of the biogas slurry settling tank of the livestock and poultry farm, lignocellulosic biomass, mineral clay or cultivated soil powder as raw materials for various pretreatments and mixing and kneading into balls in a certain ratio. A new type of plant cultivation substrate is prepared by dark combustion under the control of water content, oxygen equivalent and starting temperature. On this basis, the present application solves the harmless disposal of the solid precipitate at the bottom of the biogas slurry settling tank of the livestock and poultry farm, and achieves good social and economic benefits. The cultivation substrate prepared by the present application can be used for the cultivation of high-grade vegetables, medicinal materials, flowers, forest trees and fruit trees, and has the advantages of long fertilizer effect and good fertilizer and moisture retention effect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Fig. 2 shows the effect of the cultivation substrate on the growth of glass lettuce after 45 days of continuous cultivation; DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the related drawings. Several embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0028] In the present document, the term "%" means "mass %" unless otherwise specified; the term "pg / mL" means micrograms per milliliter. In the present document, the term "%" means "mass %" based on the total weight of the composition of the present application unless otherwise specified.

[0029] In the present document, all ranges are inclusive of each particular value within the given range and of the sub-ranges between the given range. For example, the range of 1 to 5 specifically includes 1, 2, 3, 4, and 5, as well as sub-ranges such as 2 to 5, 3 to 5, 2 to 3, 2 to 4, 1 to 4, etc.

[0030] Example 1

[0031] A method for preparing a plant cultivation substrate, comprising the following steps:

[0032] Step 1: Dry and crush the solid precipitate at the bottom of the biogas slurry settling tank of an intensive chicken farm to 60 mesh for use;

[0033] Step 2: Take dry rice straw, crush it to 60 mesh, spray it with dilute phosphoric acid at a mass fraction of 7%, mix well, compact, and pretreat for 24 hours. The amount of dilute phosphoric acid is 50% (v / w) of the mass of the lignocellulosic biomass powder;

[0034] Step 3: Spray the mineral clay without coarse sand with magnesium oxide emulsion equivalent to 25% of its dry weight (the ratio of magnesium oxide to water is 1:4), mix well, compact, and seal with plastic for 24 hours, then spread out, dry, and crush to 60 mesh;

[0035] Step 4: Take 5 parts of the dried solid precipitate at the bottom of the biogas slurry settling tank of an intensive chicken farm, 2 parts of the lignocellulosic biomass powder pretreated with phosphoric acid, and 2 parts of the magnesium ion saturated soil powder, mix well, knead into balls (10 mm in diameter) with a balling machine, and dry, controlling the water content to 12%;

[0036] Step 5: Put the mixture of the bottom solid precipitate powder of the intensive chicken farm biogas slurry settling pond, the phosphoric acid pretreated lignocellulosic biomass powder, and the magnesium ion saturated soil powder into a sealed muffle furnace, turn on the power to rapidly raise the temperature in the inner chamber to 106℃, open the air outlet and air inlet of the muffle furnace during the temperature rising process to maintain for 15 min to enable the water vapor to be fully discharged; then close the air inlet and air outlet of the muffle furnace, rapidly raise the temperature to 450℃, the dark combustion starting temperature, and stop heating within 10 min, control the amount of the mixture of the bottom solid precipitate powder of the intensive chicken farm biogas slurry settling pond, the phosphoric acid pretreated lignocellulosic biomass powder, and the magnesium ion saturated soil powder added in the inner chamber of the muffle furnace to limit the oxygen supply to 50% of the oxygen required for complete combustion of organic matter, achieve dark combustion and heat release to maintain the reaction for 4 h, and obtain the porous and nutrient-rich plant cultivation substrate with a high cation substitution amount.

[0037] Example 2

[0038] A method for preparing a plant cultivation substrate, which specifically comprises the following steps:

[0039] Step 1: Dig the bottom solid precipitate of the intensive pig farm biogas slurry settling pond, dry it, crush it to 50 mesh, and reserve it for use;

[0040] Step 2: Crush the rice hulls to 50 mesh, spray them with 5% dilute phosphoric acid by mass fraction, mix and compact them, pretreat them for 36 h, and the amount of dilute phosphoric acid is 40% of the mass of the rice hull powder (v / w);

[0041] Step 3: Spray the kaolin clay mineral particles with magnesium oxide emulsion equivalent to 20% of the dry weight of the kaolin clay mineral particles (the ratio of magnesium oxide to water is 1:4), mix them evenly, compact them, seal them with plastic, and diffuse them for 24 h, then spread them out, dry them, and crush them to 50 mesh;

[0042] Step 4: Take 5 parts of the dried bottom solid precipitate powder of the intensive pig farm biogas slurry settling pond, 3 parts of the phosphoric acid pretreated rice hull powder, and 1 part of the magnesium ion saturated kaolin powder, mix them thoroughly, knead them into balls (12 mm in diameter) with a balling machine, and dry them, and control the water content to be 10%;

[0043] Step 5: Place the mixed spheres of solid sediment powder from the bottom of the intensive pig farm biogas slurry sedimentation tank, phosphoric acid pretreated rice husk powder, and magnesium ion saturated kaolin clay powder prepared in Step 4 into a well-sealed muffle furnace. Turn on the power to rapidly raise the internal temperature to 109°C. During this heating process, open the muffle furnace's outlet and inlet for 12 minutes to allow sufficient water vapor to escape. Then close the muffle furnace's inlet and outlet, rapidly raise the temperature to the smoldering start-up temperature of 450°C, and stop heating within 8 minutes. Control the amount of the mixed spheres of solid sediment powder from the bottom of the livestock and poultry farm biogas slurry sedimentation tank, phosphoric acid pretreated lignocellulosic biomass powder, and magnesium ion saturated kaolin clay added to the inside of the muffle furnace to limit the oxygen supply equivalent to 45% of the oxygen required for complete combustion of the organic matter. Achieve smoldering and exothermic reaction maintenance for 5 hours to obtain a porous, nutrient-rich plant cultivation substrate with high cation exchange capacity.

[0044] Example 3

[0045] A method for preparing a plant cultivation substrate, which specifically includes the following steps:

[0046] Step 1: Excavate the solid sediment from the bottom of the biogas slurry sedimentation tank in the intensive chicken farm, dry it, and crush it to 60 mesh for later use;

[0047] Step 2: Take dry rice straw and crush it to 60 mesh. Spray it with 7% dilute phosphoric acid and mix it evenly. Compact and pretreat for 24 hours. The amount of dilute phosphoric acid used is 50% (v / w) of the mass of the lignocellulosic biomass powder.

[0048] Step 3: Spray the mineral clay (which does not contain coarse sand) with magnesium oxide emulsion equivalent to 25% of its dry weight (the ratio of magnesium oxide to water is 1:4), mix evenly, compact, seal with plastic and spread for 24 hours, then spread out to dry and crush through a 60-mesh sieve.

[0049] Step 4: Take 5 parts of dried solid sediment powder from the bottom of the biogas slurry sedimentation tank of the intensive chicken farm, 2 parts of phosphoric acid pretreated lignocellulosic biomass powder, and 2 parts of magnesium ion saturated soil powder. Mix them thoroughly and shape them into balls (10mm in diameter) using a ball fertilizer machine. Let them dry, controlling the moisture content to be 12%.

[0050] Step 5: Place the mixed pellets of solid sediment powder from the bottom of the intensive chicken farm biogas slurry sedimentation tank prepared in Step 4, phosphoric acid pretreated lignocellulosic biomass powder, and magnesium ion saturated soil powder into a well-sealed muffle furnace. Turn on the power to rapidly raise the internal temperature to 106°C. During this heating process, open the muffle furnace's outlet and inlet and maintain this temperature for 15 minutes to allow sufficient water vapor to escape. Then close the muffle furnace's inlet and outlet, rapidly raise the temperature to 450°C, and immediately stop heating. Open the muffle furnace's inlet and outlet to rapidly cool the temperature to room temperature to directly obtain the plant cultivation substrate (without undergoing smoldering reaction).

[0051] Example 4

[0052] The determination of slow-release fertilizer effect in cultivation substrates includes the following steps:

[0053] Step 1: Take 20g of the cultivation substrate prepared in Example 1 and press it into powder. Weigh out 3 portions of cultivation substrate powder, 5g each.

[0054] Step 2: Place the cultivation substrate powder prepared in Step 1 into three 250 mL Erlenmeyer flasks, add the corresponding mass of ultrapure water at a solid-liquid ratio (mass:volume) of 1:20, tighten the stoppers, and fix them vertically in a water bath shaker. Set the oscillation mode to horizontal reciprocating oscillation, control the water bath temperature at 25±1℃, adjust the oscillation frequency to 100 times / min, and the amplitude to not less than 40 mm.

[0055] Step 3: In Step 2, the start of oscillation is recorded as time 0 (0h). When the oscillation time is 0 h, 2 h, 4 h, 6 h, 8 h, 12 h and 24 h respectively, 5 mL of the well mixed suspension is taken from each of the three conical flasks and filtered through an aqueous filter membrane with a pore size of 0.22 micrometers to obtain water samples for water quality determination.

[0056] Step 4: The total phosphorus (TP) content of the water sample obtained in Step 3 was determined by the ammonium molybdate spectrophotometric method as specified in GB11893-39, and the ammonia nitrogen content was determined by the nanospray spectrophotometric method as specified in HJ535-2009. A total carbon / total nitrogen analyzer (Multi N / C3100, Analytik Jena AG, Germany) was used to determine the total carbon and total nitrogen contents. The results are shown in Table 1. The data show that the cultivation substrate exhibits a slow release trend of nitrogen, phosphorus, and carbon in the aquatic environment, indicating that the cultivation substrate prepared by this process has slow-release fertility.

[0057] Table 1. The novel cultivation substrate of this invention has good slow (controlled) nutrient release properties.

[0058]

[0059] Example 5

[0060] The evaluation of the maturity of the cultivation substrate includes the following steps:

[0061] Step 1: Take 50g each of the cultivation substrate prepared in Example 1 (after smoldering reaction) and the cultivation substrate prepared in Example 3 (without smoldering reaction), and press them into powder. Take three equal portions of each, each portion weighing 10g.

[0062] Step 2: Place the cultivation substrate powder obtained in Step 1 into six 250 ml Erlenmeyer flasks, and add the corresponding mass of ultrapure water at a solid-liquid ratio (mass:volume) of 1:10. After tightening the stoppers, fix the flasks vertically in a water bath shaker, set the shaking mode to horizontal reciprocating oscillation, control the water bath temperature at 25±1℃, adjust the oscillation frequency to 100 times / min, and the amplitude to not less than 40 mm.

[0063] Step 3: After shaking and extracting for 1 hour in Step 2, remove the conical flask and let it stand for 0.5 hours. Filter the supernatant using a pre-prepared vacuum filtration device. Collect the filtrate and shake well to obtain the cultivation substrate extract. The extract should be used on the same day or stored at 0-4℃ for no more than 48 hours.

[0064] Step 4: Take six 9cm diameter glass petri dishes. Place a piece of qualitative filter paper of similar diameter in each dish, then evenly place 20 plump lettuce seeds of roughly the same size in each dish. Add 10ml of the cultivation substrate extract obtained in Step 3, cover the dishes, and incubate in a 25℃ incubator in the dark for 96 hours. Count the number of germinated seeds and measure the root length. Use ultrapure water as a control for a blank test. Calculate the seed germination index (GI) according to Appendix F, "Determination of Seed Germination Index (GI)," in NY-525-2021. NY-525-2021 stipulates that a GI ≥ 70% indicates that the organic fertilizer has reached the required level of decomposition. The results are shown in Table 2. The seed germination index of the cultivation substrate prepared by the smoldering process is 71.11%, which meets the relevant standard requirements, indicating that the cultivation substrate prepared by this process has a good degree of decomposition and is essentially non-toxic to the seeds.

[0065] Table 2 Evaluation of the maturity of the cultivation substrate

[0066]

[0067] Example 6

[0068] The cultivation substrate of fertilized mineral clay for glass lettuce cultivation includes the following steps:

[0069] Step 1: Take 6 portions of mineral clay without coarse sand, each weighing 3 kg, and place them into cylindrical flower pots with dimensions of 20×20×20cm. Three of the flower pots are used as fertilizer groups, with 8% of the clay mass replaced by the cultivation substrate produced in Example 1 and mixed evenly. The other 3 groups are used as control groups.

[0070] Step 2: Evenly sow 281 glass lettuce seeds onto the surface of each flowerpot prepared in Step 1. After sowing, evenly sprinkle a thin layer of mineral clay to cover the seeds, and pour 400g of deionized water into each flowerpot. Then, cover the flowerpots and place them in a light incubation room at 25±1℃ for 96 h. After that, measure the germination rate, root length, and plant height. The results are shown in Table 3. The germination rate of the fertilized group was slightly lower than that of the control group, while the growth rate of the roots and above-ground parts of the plants after germination was higher in the fertilized group than in the control group.

[0071] Table 3. Fertilized mineral clay substrate promoted the growth of glass lettuce.

[0072]

[0073] Step 3: After completing Step 2, randomly remove some of the sprouted seedlings so that each flowerpot contains 100 seedlings. Then, uncover the flowerpots and allow them to be exposed to light for 24 hours a day. At 11:00 AM every day, pour 200g of deionized water into each flowerpot.

[0074] Step 4: Twenty days after sowing, some seedlings were randomly removed again, leaving 20 seedlings in each pot. The seedlings were then cultivated under the original conditions for another 25 days before harvesting. Fresh weight, plant height, and root length were measured. The results are shown in Table 4. The root length, average height, and fresh weight of the fertilized group were significantly higher than those of the control group, indicating that this cultivation substrate has the potential to fertilize poor soil. Figure 1 .

[0075] Table 4. Differences in growth of glass lettuce harvested after 45 days of continued cultivation.

[0076]

[0077] Although the description of the invention has been quite detailed and particularly of several described embodiments, it is not intended to limit it to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A method for preparing a plant cultivation substrate, characterized in that, Includes the following steps: S1: Dry and crush the solid sediment at the bottom of the biogas slurry sedimentation tank in the livestock and poultry farm to 40-60 mesh to obtain the first matrix; S2: Crush lignocellulosic biomass to 40-60 mesh, then spray it with a 5%-10% dilute phosphoric acid solution, mix and compact it for 24-48 hours to obtain the second matrix; S3: Spray magnesium oxide emulsion onto mineral clay or cultivated soil powder that does not contain coarse sand, mix well, compact, seal and diffuse for 24-36 hours, then spread out to dry and crush through a 40-60 mesh sieve to obtain the third matrix. S4: Mix 4-5 parts of the first matrix obtained in step S1, 2-3 parts of the second matrix obtained in step S2, and 1-2 parts of the third matrix obtained in step S3, then shape them into balls with a diameter of 8mm-15mm and air dry them, controlling the moisture content to be 10%-12%, to obtain a mixed ball of the first matrix, the second matrix, and the third matrix. S5: Place the mixed balls obtained in step S4 into a closed muffle furnace and heat the inner chamber temperature to 105℃-110℃. At the same time, open the air outlet and air inlet of the muffle furnace and maintain this temperature for 10min-15min. Then close the air inlet and air outlet of the muffle furnace and raise the temperature to 450℃. Heat for 5min-10min and control the oxygen supply in the muffle furnace to be 45%-50% of the oxygen required for the complete combustion of organic matter in the mixed balls. Perform a smoldering reaction for 1h-5h to finally obtain the plant cultivation substrate. The amount of dilute phosphoric acid solution used should be 40%-60% of the mass of the lignocellulose organism.

2. The preparation method according to claim 1, characterized in that, Livestock and poultry farms include intensive chicken farms or intensive pig farms.

3. The preparation method according to claim 1, characterized in that, Lignocellulosic biomass includes at least one of rice straw, wheat straw, corn stalks, bamboo shavings, pine sawdust, and rice husks.

4. The preparation method according to claim 1, characterized in that, In step S3, the amount of magnesium oxide emulsion sprayed is 20% to 30% of the dry weight of mineral clay or cultivated soil without coarse sand.

5. The preparation method according to claim 4, characterized in that, The ratio of magnesium oxide to water in the magnesium oxide emulsion is 1:

4.

6. A plant cultivation substrate, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the plant cultivation substrate according to claim 6 in plant cultivation.

8. The application according to claim 7, characterized in that, The plants mentioned include high-end vegetables, medicinal herbs, flowers, fruit trees, or forest trees.

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