A reusable grass-free charcoal oilseed rape seedling special substrate and a preparation method thereof

Abstract

The application discloses a reusable no-grass charcoal rapeseed seedling special substrate and a preparation method thereof. The reusable no-grass charcoal rapeseed seedling special substrate comprises 50-65% of an organic carrier, 30-45% of inorganic auxiliary materials and 5-7% of nutrient and biological control agents; the percentage is a mass percentage; the nutrient and biological control agents are composed of slow-release nutrient packages and microbial agents with a mass ratio of (3-5):(1-2); the slow-release nutrient includes sulfur-coated urea, polyphosphate and potassium humate; the mass ratio of N in the sulfur-coated urea, P2O5 in the polyphosphate and K2O in the potassium humate is (15-20):(10-15):(18-25), and the film thickness of the sulfur-coated urea is 10-15 mu m; the biological control agent is at least one of Trichoderma harzianum T-22 or Bacillus subtilis BS-208. The application solves the problems of nutrient imbalance, structural defects and biological pollution in the rapeseed seedling stage through precise formula design, directional fermentation process and function module integration.

Description

Technical Field

[0001] This invention relates to a reusable peat-free rapeseed seedling substrate and its preparation method, belonging to the field of rapeseed planting technology. Background Technology

[0002] Currently, the preparation of rapeseed seedling substrate mainly relies on the following technical routes:

[0003] (1) General seedling substrate:

[0004] Composition and proportion: Mainly composed of peat moss, vermiculite, and perlite (typical volume ratio 6:2:2), with a small amount of compound fertilizer added (N-P2O5-K2O=15-15-15).

[0005] Process steps: coarse crushing of raw materials → simple mixing → adjusting pH to 6.0-6.5 → packaging.

[0006] Current application status: It is widely used in the seedling cultivation of solanaceous and leafy vegetables, but its effect is not good when directly applied to rapeseed seedling cultivation.

[0007] (2) Organic waste recycling substrate:

[0008] Raw materials: Agricultural waste (such as rice husks, mushroom residue, and straw) is used for composting and fermentation to replace peat moss.

[0009] Process: composting fermentation (temperature 50-60℃ maintained for 15 days) → addition of inorganic auxiliary materials (such as leavening agents).

[0010] Defect: Incomplete fermentation leads to an imbalance in the carbon-nitrogen ratio (C / N > 30), inhibiting nitrogen absorption by seedlings.

[0011] (3) Chemically synthesized lightweight matrix:

[0012] Method: A porous structure was constructed using chemical materials such as polyacrylamide and urea-formaldehyde resin, and nutrient solution was added artificially.

[0013] Development bottlenecks: High cost (cost per acre is more than 3 times that of traditional substrates), and long-term use can easily lead to salt accumulation (EC value > 3.0mS / cm).

[0014] The existing rapeseed seedling substrate has the following problems:

[0015] (1) The nutrient supply is not matched with the needs of rapeseed seedlings:

[0016] Rapeseed seeds are sensitive to nitrogen from germination to the 2-leaf stage; high concentrations of ammonium nitrogen (>50 mg / kg) inhibit radicle elongation (experimental data can be found in *Acta Agronomica Sinica*, 2021). However, general-purpose substrates release nutrients too quickly, requiring low nutrient concentrations (EC < 1.5 mS / cm) during the seedling stage. But the initial EC values ​​of existing substrates are generally > 2.0 mS / cm, leading to a seedling burn rate > 10%.

[0017] (2) The physical structure is not suitable for the development of rapeseed roots:

[0018] Unreasonable pore distribution: The proportion of large pores (>100μm) is <15% (ideal value is 25%-30%), and root hypoxia leads to a 40%-50% reduction in the number of lateral roots.

[0019] Poor water retention: The substrate moisture content fluctuates greatly (>80% after irrigation → <30% after 24 hours), causing water stress during the cotyledon stage.

[0020] (3) High risk of biological contamination:

[0021] Pathogen residues: Incompletely fermented organic matter carries root rot pathogens (such as Pythium ultimum), with an incidence rate of 12%-18% during the seedling stage (data from comparative experiments).

[0022] Allelopathic inhibition: When the concentration of phenolic acids (such as vanillic acid) in straw compost is >20 μg / g, the elongation of the hypocotyl of rapeseed is inhibited (supported by literature: DOI 10.1016 / j.plaphy.2020.05.035).

[0023] (4) Insufficient environmental adaptability:

[0024] Poor temperature buffering capacity: Traditional substrates have high thermal conductivity (>0.8W / m·K), and the root layer temperature is 3-5℃ lower than the environment during early spring seedling cultivation, delaying seedling emergence by 2-3 days.

[0025] Low pH stability: The pH of the peat substrate dropped from 6.2 to 4.8 after continuous irrigation, leading to calcium deficiency and curling of the heart leaves.

[0026] (5) Sustainability deficiencies

[0027] Dependence on peat resources: Peat mining damages wetland ecosystems, and the EU has legislated to restrict its use (an environmental tax will be levied from 2024), forcing costs to rise.

[0028] Non-reusable: Traditional substrates suffer from severe compaction after use (bulk density drops from 0.3 g / cm³). 3 Increased to 0.9 g / cm³ 3 The secondary utilization rate is less than 30%. Summary of the Invention

[0029] This invention provides a reusable peat-free rapeseed seedling substrate and its preparation method. Through precise formula design, directional fermentation process and functional module integration, it systematically solves problems such as nutrient imbalance, structural defects and biological pollution in the seedling stage.

[0030] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0031] A reusable, peat-free rapeseed seedling substrate comprises 50-65% organic carrier, 30-45% inorganic additives, and 5-7% nutrient and biological regulators; the percentages are by weight.

[0032] The nutrient and biological regulator consists of a slow-release nutrient pack and a microbial agent in a mass ratio of (3-5):(1-2);

[0033] The slow-release nutrients include sulfur-coated urea, ammonium polyphosphate, and potassium humate; the mass ratio of N in sulfur-coated urea, P2O5 in ammonium polyphosphate, and K2O in potassium humate is (15-20):(10-15):(18-25), and the coating thickness of sulfur-coated urea is 10-15 μm;

[0034] The bioregulator is composed of Trichoderma harzianum T-22, Bacillus subtilis BS-208, and Bacillus mucilaginosus ACCC 10015, with a volume ratio of 1:1:0.5 to 1. Unless otherwise specified, all percentages in this application are by mass; all proportions unless otherwise specified are by mass ratios.

[0035] The total mass of the above-mentioned organic carrier, inorganic excipients, and nutrients and bioregulators is 100%.

[0036] This application's slow-release nutrient pack has a release cycle of 30-40 days, matching the demand curve of rapeseed seedlings, which is characterized by "low nutrient requirements before the 2-leaf stage and increased nutrient requirements after the 4-leaf stage".

[0037] Trichoderma harzianum T-22: spore concentration ≥1×10 8 CFU / g degrades allelochemicals such as vanillic acid and ferulic acid, directly breaking down the ester bonds or carboxyl groups of allelochemicals to render them non-toxic and promote healthy plant growth.

[0038] Bacillus subtilis BS-208: spore concentration ≥5×10 7 CFU / g, secretes antimicrobial peptides to inhibit root rot bacteria (inhibition rate ≥85%).

[0039] To improve the stability of rapeseed seedling growth, the inorganic additives contain functional additives. These functional additives consist of thermosensitive gel microspheres and palygorskite powder in a mass ratio of (2-3):(1-2). The thermosensitive gel microspheres are acrylic acid-chitosan copolymer microspheres with a particle size of 0.5-1 mm, a phase transition temperature of 15-25℃, which release heat at low temperatures (heat release during solidification) and absorb heat at high temperatures, maintaining a stable root zone temperature within ±2℃ and a water holding capacity of ≥400%. The palygorskite powder has a mesh size of 200, a pH buffering capacity of ≥50 mmol / kg, and stabilizes the substrate pH. The palygorskite powder adsorbs organic acids secreted by Bacillus mucilaginosus through ion exchange, delaying acid depletion and extending the phosphorus activation cycle to more than 30 days.

[0040] The aforementioned inorganic excipients consist of expanded vermiculite, perlite, and functional additives in a mass ratio of (15-25):(10-15):(3-5).

[0041] The expanded vermiculite described above has a particle size of 3-6 mm and a bulk density of 0.1-0.2 g / cm³. 3 Porosity ≥ 80%; perlite, particle size 2-4 mm, pre-washed to EC value ≤ 0.5 mS / cm to reduce salt interference.

[0042] To improve the seedling survival rate, the organic carrier is composed of a mushroom residue-biochar composite and well-rotted straw compost in a mass ratio of (40-60):(5-10); the mushroom residue-biochar composite is made of fermented mushroom residue and rice husk char in a mass ratio of 1:(1-2), with a moisture content ≤10%.

[0043] The C / N ratio of the above-mentioned fermentation residue is 25-30; the specific surface area of ​​rice husk charcoal is ≥200m². 2 / g, porosity ≥80%; phenolic acid content in well-rotted straw compost ≤5μg / g, cellulose degradation rate ≥85%.

[0044] The raw materials used for the above-mentioned composting of decomposed straw are a mixture of wheat straw (cut into 3-5cm sections) and chicken manure with a C / N ratio of 25-28:1.

[0045] The aforementioned rice husk charcoal replaces peat moss, providing a stable source of organic matter, adsorbing phenolic acid allelochemicals (adsorption rate > 90%), and optimizing the pore structure.

[0046] The preparation method of the above-mentioned microbial residue-biochar composite includes the following steps:

[0047] 1) Crushing and conditioning of mushroom residue:

[0048] Fresh edible mushroom cultivation waste (oyster mushroom residue, shiitake mushroom residue) is crushed to a particle size ≤5mm and the moisture content is adjusted to 55-60% (by spraying deionized water or drying) to obtain mushroom residue;

[0049] 2) Directional fermentation:

[0050] Microbial agent addition: Inoculate the fungal residue with cellulose-decomposing bacteria at an inoculation amount of 0.5-1 wt% (based on the weight of the fungal residue); wherein, the cellulose-decomposing bacteria are Trichoderma viride and Bacillus licheniformis in a volume ratio of 1:2;

[0051] Fermentation conditions: Temperature 55-60℃, kill insect eggs (lethal temperature for flea beetle eggs ≥53℃), retain the activity of functional microorganisms, maintain for 5-7 days, turn the pile once every 24 hours to ensure oxygen penetration, and obtain fermented residue; premix 0.2wt% of Bacillus mucilaginosus spore powder (by weight of fermented residue) into the fermented residue, and use the residual phosphate in the fermented residue as an inducer to activate the phosphate solubilization function of the strain in advance.

[0052] 3) Biochar composite:

[0053] The fungal residue obtained in step 2) is mixed with rice husk charcoal at a mass ratio of 1:(1~2), and dried at 50~60℃ until the moisture content is ≤10% to form a fungal residue-biochar composite.

[0054] The above-mentioned method for preparing decomposed straw compost includes the following steps:

[0055] 1) Raw material pretreatment:

[0056] Cut wheat straw into 3-5cm sections and mix it with chicken manure at a C / N ratio of 25-28:1, adjusting the initial moisture content to 60-65%.

[0057] 2) High-temperature fermentation (in three stages):

[0058] Phase 1 (warming period): Add 0.2 wt% EM bacteria and 0.1 wt% white rot fungi based on the weight of wheat straw, and maintain at 40-50℃ for 3 days;

[0059] Phase 2 (High Temperature Period): Maintain 55-65℃ for 10-12 days, turning the pile daily to kill pathogens (e.g., Pythium spore inactivation rate > 99%).

[0060] Stage 3 (Composting Period): Maintain 40-45℃ for 7 days, and spray with lime water to adjust the pH to 6.5-7.0;

[0061] 3) Screening and detection:

[0062] Undegraded coarse fibers were removed by passing the material through a 10-mesh sieve, and the phenolic acid content (HPLC method) was ≤5μg / g.

[0063] The preparation method of the above-mentioned reusable peat-free rapeseed seedling substrate includes the following steps:

[0064] 1) Add the organic carrier (microbial residue-biochar composite + decomposed straw compost) and expanded vermiculite and perlite from the inorganic auxiliary materials into a twin-shaft mixer in proportion, and mix at a speed of 20-25 rpm for 15-20 minutes to ensure uniformity (coefficient of variation ≤5%).

[0065] 2) Under conditions of ≤40℃, add the slow-release nutrient pack, the mixture of Trichoderma harzianum T-22 and Bacillus subtilis BS-208, the temperature-sensitive gel microspheres, Bacillus thuringiensis (which needs to be packaged separately and added before adding palygorskite powder) and palygorskite powder in stages. Except for Bacillus thuringiensis, after adding the previous material, stir at 20-25 rpm for 3-5 minutes before adding the next material; after adding Bacillus thuringiensis, stir at 15-20 rpm for 1-3 minutes, add palygorskite powder, and stir at 20-25 rpm for 5-8 minutes to obtain the mixed matrix;

[0066] In other words, compared to other materials, the stirring speed and time after adding Bacillus subtilis are shortened to avoid mechanical shearing damage to the bacterial cells. The stirring speed and temperature after adding the slow-release nutrient pack, the mixture of Trichoderma harzianum T-22 and Bacillus subtilis BS-208, and the thermosensitive gel microspheres are 20-25 rpm for 3-5 minutes; the stirring speed and temperature after adding Bacillus subtilis are 15-20 rpm for 1-3 minutes; and the stirring speed and temperature after adding palygorskite powder are 20-25 rpm for 5-8 minutes.

[0067] 3) Spray citrate-potassium dihydrogen phosphate buffer (0.1 mol / L) into the mixed matrix to adjust the matrix pH to 6.0-6.5; then add deionized water or humic acid solution to control the initial EC value at 1.2-1.5 mS / cm.

[0068] 4) Using ozone fumigation at a concentration of 50-80 ppm for 2-3 hours can inactivate residual pathogens (such as Fusarium inactivation rate ≥99.5%), while preserving beneficial microorganisms such as Trichoderma and Bacillus (survival rate ≥90%).

[0069] 5) The moisture content should be controlled at 30-35% to prevent premature microbial germination and ensure storage stability. Vacuum packaged in 5-10L bags, with a storage temperature of ≤25℃ and a shelf life of ≥6 months.

[0070] In step 2) above, the temperature should be controlled at ≤40℃ to avoid inactivation of the fungal agent (Trichoderma spore survival rate ≥95%).

[0071] This application solves the problem of nutrient release mismatch:

[0072] The existing substrate has an excessively high initial EC value (>2.0 mS / cm), resulting in a seedling burn rate of >10% during seed germination; nitrogen form imbalance (ammonium nitrogen content >50%) inhibits radicle development; and the lack of a slow-release mechanism makes it unable to match the seedling growth curve of "low nutrients in the early stage and gradual demand in the later stage".

[0073] The slow-release nutrient pack of this application controls the release rate by adjusting the thickness of the sulfur coating (10-15μm), keeping the EC value stable at 1.2-1.5mS / cm; ammonium polyphosphate (water-soluble ≤5%) provides a neutral phosphorus source, avoiding the toxicity of ammonium nitrogen (ammonium nitrogen content <30% in the seedling stage), and matching the demand curve of rapeseed seedlings: "low nutrient requirement before the 2-leaf stage and increased nutrient requirement after the 4-leaf stage".

[0074] This application optimizes the physical structure of a special substrate for rapeseed seedling cultivation, overcoming the limitations imposed on rapeseed seedling cultivation by the pore distribution and water retention defects of traditional substrates, and adapting it to root development:

[0075] The existing substrate has a macroporous ratio of <15%, leading to root hypoxia and a 40%-50% reduction in lateral root numbers; water holding capacity fluctuates drastically (80% after irrigation → <30% after 24 hours), causing water stress during the cotyledon stage; and the bulk density is too high (>0.8 g / cm³). 3 This hinders the root development and nutrient absorption efficiency;

[0076] This application involves biochar (porosity ≥ 80%) and vermiculite (bulk density 0.1-0.2 g / cm³). 3 The synergistic effect increases the proportion of macropores to 25-30%; the water holding capacity of the temperature-sensitive gel microspheres is ≥400%, and the water content fluctuation of the matrix is ​​controlled within 50%-70% (the fluctuation range of traditional matrix is ​​30-80%).

[0077] This application eliminates the risks of biocontamination and allelopathic inhibition:

[0078] The existing substrate contains uncomposted organic matter that carries root rot pathogens (such as Pythium ultimum), resulting in a disease rate of >12% during the seedling stage; phenolic allelochemicals in straw compost (such as vanillic acid concentration >20μg / g) inhibit hypocotyl elongation; and the survival of insect eggs (flea beetles, aphids) increases the cost of pest control during the seedling stage.

[0079] This application uses ozone fumigation instead of traditional high-temperature sterilization, which eliminates pathogenic microorganisms while preserving the activity of Trichoderma harzianum T-22 (spore survival rate ≥95%); Trichoderma degrades vanillic acid to <5μg / g (HPLC verification), eliminating allelopathic inhibition.

[0080] This application enhances environmental adaptability and stability:

[0081] The existing substrate has a high thermal conductivity (>0.8W / m·K), and the root layer temperature is 3-5℃ lower than the ambient temperature under low temperature conditions, which delays seedling emergence; after continuous irrigation, the pH drops sharply from 6.2 to 4.8, inducing calcium deficiency physiological diseases (such as heart leaf curling); salt accumulation (EC value >3.0mS / cm) causes salt stress in seedlings, resulting in a seedling emergence rate decrease of >20%.

[0082] This application utilizes palygorskite powder with a pH buffering capacity ≥50 mmol / kg, ensuring a stable pH of 6.0-6.8 after irrigation (compared to pH fluctuations of 4.8 in traditional substrates); biochar-gel microspheres synergistically reduce thermal conductivity to 0.3-0.5 W / m·K (compared to >0.8 W / m·K in traditional substrates); and EC values ​​are controlled at 1.2-1.5 mS / cm, mitigating salt stress. This improves seedling growth obstacles caused by insufficient substrate temperature, pH, and salt buffering capacity.

[0083] This application achieves matrix decarbonization and sustainability:

[0084] Existing substrate peat has a high dependence (over 60%), and its extraction damages wetland ecosystems and costs are rising year by year; after use, the substrate becomes severely compacted (bulk density drops from 0.3 g / cm³). 3 Increased to 0.9 g / cm³ 3 The reuse rate is less than 30%; the cost of chemically synthesized matrix is ​​high (the cost per acre is more than 3 times that of traditional matrix), making it difficult to promote.

[0085] This application utilizes bacterial residue-biochar to replace peat moss, reducing wetland damage; the addition of phosphate-solubilizing bacteria (Bacillus mucilaginosus) enhances the phosphorus availability of the continuous cropping substrate, achieving a reuse rate of 80% (compared to <30% for traditional substrates). This resolves the core contradiction of unsustainable resources and poor economic efficiency in traditional technologies.

[0086] This invention addresses the core needs of rapeseed seedlings for low salt stress, high oxygen environment, stable temperature, biosafety, and sustainability. By systematically solving the above five categories of technical problems, it achieves the following objectives:

[0087] The seedling burn rate during the seedling stage was reduced from >10% to <3%;

[0088] Increase germination rate to >95% (compared to an average of 78% for traditional substrates);

[0089] Reduce the frequency of substrate replacement during continuous cropping (extend the replacement period from annually to a 3-year recycling period).

[0090] Any techniques not mentioned in this invention are based on existing technologies.

[0091] This invention, through innovative formula and process design, significantly outperforms existing technologies in terms of seedling efficiency, resource utilization, and environmental friendliness. Specific beneficial effects are as follows:

[0092] I. Significantly improved seedling efficiency and survival rate:

[0093] 1. Significant improvement in germination rate and seedling vigor rate:

[0094] Germination rate: increased from 78% in traditional substrates to ≥95% (example data);

[0095] Seedling burn rate: reduced from >10% to ≤3%, with precise control of EC value (1.2-1.5mS / cm) to avoid salt stress;

[0096] Seedling vigor rate: The number of lateral roots increased by 50%, and the root dry weight increased by 45% (control experiment P<0.01).

[0097] 2. Shortened the seedling cultivation cycle:

[0098] Emergence time: In early spring under low temperature conditions, the root zone temperature is stable (fluctuating by ±2℃), and the emergence time is shortened by 2-3 days;

[0099] Seedling cycle: The proportion of seedlings reaching the standard at the 4-leaf stage increased from 60% to 90%, saving more than 20% in seedling management costs.

[0100] II. Optimized resource utilization and cost control:

[0101] 1. Reduced raw material costs:

[0102] By completely replacing 60-70% of the existing peat moss in the substrate, zero peat moss is achieved, and the cost of the microbial residue-biochar composite is only 40% of that of peat moss (the average substrate cost per mu is reduced from 800 yuan to 480 yuan).

[0103] 2. Waste resource utilization has been achieved:

[0104] The utilization rate of agricultural waste such as mushroom residue and straw reaches 100%, reducing environmental pollution.

[0105] 3. Extends the service life of the substrate:

[0106] Improved reusability: increased from <30% in traditional substrates to ≥80%, and maintained porosity >70% even after 3 consecutive years of cropping; after adding Bacillus mucilaginosus, the available phosphorus content in the substrate remained ≥25mg / kg after 3 consecutive years of cropping (initial value was 35mg / kg), while the control group (without phosphorus-solubilizing bacteria) decreased to ≤8mg / kg.

[0107] Reduced nutrient supplementation costs: Slow-release nutrient packs reduce the frequency of topdressing, saving 30% on fertilizer input.

[0108] III. Environmentally friendly and with significant ecological benefits:

[0109] 1. Reduced ecological damage:

[0110] Zero use of peat: avoids wetland mining, reducing carbon emissions by 50 kg per ton of substrate (based on LCA life cycle assessment);

[0111] Chemical pesticide use reduction: Microbial inoculants suppress diseases, and the amount of fungicide used during the seedling stage is reduced by 70%;

[0112] Eutrophication of water bodies is reduced: Bacillus mucilaginosus reduces the amount of exogenous phosphate fertilizer added by 30% by activating the soil’s inherent phosphorus, thereby reducing the risk of eutrophication of water bodies.

[0113] 2. Significant progress in pollution prevention and control:

[0114] Allelochemical degradation: Trichoderma harzianum T-22 degrades phenolic acids to a safe threshold (<5 μg / g);

[0115] Zero salt discharge: No chemically synthesized materials are added, avoiding the risk of secondary soil salinization.

[0116] IV. Improved ease of operation and stability:

[0117] 1. The process has been simplified:

[0118] Sterilization process: Ozone fumigation (2-3 hours) replaces traditional high-temperature sterilization (6-8 hours), reducing energy consumption by 60%;

[0119] Mixing uniformity: The twin-shaft mixing process ensures that the coefficient of variation of matrix composition is ≤5% (compared to >15% for traditional processes).

[0120] 2. It can adapt to environmental fluctuations:

[0121] Temperature buffer: Thermosensitive gel microspheres maintain stable root zone temperature, and the germination rate is still >90% even in low temperature environment (5℃);

[0122] pH self-regulation: Palaequa calcite powder has a buffering capacity of >50mmol / kg, and the pH stabilizes at 6.0-6.8 after continuous irrigation. Detailed Implementation

[0123] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0124] In each example: the preparation of acrylic acid-chitosan copolymer microspheres was based on the following reference: Khan MA, Azad AK, Safdar M, et al. Synthesis and characterization of acrylamide / acrylic acid Co-polymers and glutaraldehyde crosslinked pH-sensitive hydrogels[J]. Gels, 2022, 8(1):47.

[0125] The sulfur-coated urea (specifically, the "Yihua" brand slow-release urea from Sinochem Fertilizer) has a coating thickness of 10-15μm, a particle size of 2-4mm, and a 24-hour water dissolution rate of ≤5%, meeting the GB / T 23348-2021 slow-release fertilizer standard.

[0126] Ammonium polyphosphate (purchased from Sichuan Longmang) is a long-chain, water-insoluble phosphorus source with a degree of polymerization ≥20, a P2O5 content ≥70%, a pH of 6.0-7.0, and a particle size of 80-100 mesh.

[0127] The potassium humate (purchased from Shanxi Meibang) has a humic acid content of ≥60%, a K2O content of ≥12%, a water-insoluble matter content of ≤5%, and a pH of 8.0-9.5, which meets the HG / T 5046-2016 standard for humic acid fertilizers.

[0128] Trichoderma harzianum T-22 was purchased from the China Agricultural Microbial Culture Collection Center (ACCC 30152);

[0129] Bacillus subtilis BS-208, purchased from the China Agricultural Microbial Culture Collection Center (ACCC 11025);

[0130] Bacillus mucilaginosus was purchased from the China Agricultural Microbial Culture Collection Center (ACCC 10015).

[0131] Trichoderma viride was purchased from the China Agricultural Microbial Culture Collection Center (ACCC 30115).

[0132] Bacillus licheniformis, purchased from Jiangsu Lvke Biotechnology Co., Ltd., LK-BL01 formulation, spore concentration 6×10⁻⁶. 8 CFU / g;

[0133] EM (Effective Microorganisms) is WQ-EM compound bacterial agent from Beijing Woqi Biotechnology Co., Ltd.; white rot fungus is bio-52267 from Beijing Bio-Bio Biotechnology Co., Ltd.

[0134] Example 1: Basic formula (50% of the microbial residue-biochar composite)

[0135] (1) Formulation composition (percentage by mass)

[0136] Organic carriers account for 58%, including:

[0137] Fungal residue-biochar composite: 50% (fungal residue:biochar = 1:1)

[0138] Well-rotted straw compost: 8% (phenolic acid content 4.2 μg / g, cellulose degradation rate 87%)

[0139] Inorganic excipients account for 35%, including:

[0140] Vermiculite: 20% (particle size 4mm, bulk density 0.15g / cm³) 3 )

[0141] Perlite: 12% (3mm grain size, EC 0.4mS / cm)

[0142] Thermosensitive gel microspheres: 2% (acrylic acid-chitosan copolymer microspheres, particle size 0.5-1mm, phase change temperature 18℃, water holding capacity ≥400%)

[0143] Palaequa calcite powder: 1% (200 mesh, pH buffering capacity ≥50mmol / kg)

[0144] Nutritional and biological regulators 7%, including:

[0145] Slow-release nutrient pack: 5%; composed of sulfur-coated urea, ammonium polyphosphate, and potassium humate. The mass ratio of N in the sulfur-coated urea: P2O5 in the ammonium polyphosphate: K2O in the potassium humate is 18:12:20. Sulfur-coated urea: particle size 1-2 mm, coating thickness 10-15 μm; ammonium polyphosphate: water solubility ≤5%; potassium humate: chelated potassium. Bacillus mucilaginosus and ammonium polyphosphate form a dual-pathway phosphorus supply mode of "chemical slow release - biological activation," increasing phosphorus utilization from 30% in traditional substrates to 65%. The slow-release nutrient pack has a release cycle of 30-40 days, matching the seedling growth curve.

[0146] Microbial inoculant: 2%, composed of Trichoderma harzianum T-22, Bacillus subtilis BS-208, and Bacillus mucilaginosus in a volume ratio of 1:1:1, with Trichoderma harzianum T-22 1×10 8 CFU / g, Bacillus subtilis BS-208 5×10 7 CFU / g, Bacillus subtilis ≥2.0×10 8 CFU / g.

[0147] (2) Preparation steps:

[0148] Mushroom residue pretreatment:

[0149] The oyster mushroom residue is crushed to 3mm and the moisture content is adjusted to 58%.

[0150] Inoculate with Trichoderma viride and Bacillus licheniformis (volume ratio 1:2) at a rate of 0.8%, ferment at 58°C for 6 days, turning the pile daily, and finally add 0.2 wt% of Bacillus mucilaginosus spore powder.

[0151] After fermentation, the bacterial residue (C / N = 28) was mixed with rice husk charcoal at a ratio of 1:1 and dried at 60℃ until the moisture content was 9.5%.

[0152] Preparation of compost from well-rotted straw:

[0153] Cut wheat straw into 4cm sections and mix it with chicken manure at a C / N ratio of 25, adjusting the moisture content to 62%.

[0154] Add 0.2wt% EM (Effective Microorganisms) bacteria and 0.1wt% white rot fungi based on the weight of wheat straw. Ferment in three stages (40℃×3 days → 60℃×12 days, turning the pile daily → 45℃×7 days). Spray with lime water to adjust the pH to 6.5-7.0.

[0155] After fermentation, the sample was passed through a 10-mesh sieve, and the phenolic acid content was 4.2 μg / g (HPLC detection).

[0156] Matrix mixing:

[0157] The organic carrier and inorganic auxiliary materials, expanded vermiculite and perlite, were put into a twin-shaft mixer (22 rpm, 18 minutes).

[0158] Add the slow-release nutrient pack, the mixture of Trichoderma harzianum T-22 and Bacillus subtilis BS-208, the thermosensitive gel microspheres, Bacillus thuringiensis and palygorskite powder in the following steps, controlling the temperature to ≤38℃; except for Bacillus thuringiensis, after adding the previous material, stir at 22 rpm for 3 minutes before adding the next material. After adding Bacillus thuringiensis, stir at 18 rpm for 2 minutes, add palygorskite powder, and stir at 22 rpm for 5 minutes to obtain the mixed matrix;

[0159] Spray 0.1 mol / L citrate-potassium dihydrogen phosphate buffer into the mixed matrix to adjust the pH to 6.3, and add deionized water to adjust the EC value to 1.2 mS / cm (more suitable for salt-sensitive varieties).

[0160] Sterilization and Packaging:

[0161] Ozone fumigation (concentration 65ppm, time 2.5 hours), vacuum packaging (8L / bag, moisture content 32%).

[0162] (3) Application and Testing:

[0163] Seedling raising method:

[0164] Acupuncture tray specifications: 72-well tray, each well filled with 20mL of substrate;

[0165] Sowing: Rapeseed variety "Zhongshuang 11", 2 seeds per hole, covering with 0.5cm of soil;

[0166] Environment: Day / night temperature 20℃ / 15℃, humidity 70%, natural light.

[0167] Fifteen days after sowing, test the germination rate, seedling burn rate, root dry weight (mg), and root length (cm). Seedlings are considered mature at the 4-leaf stage.

[0168] Example 2: High biochar ratio scheme (60% of the microbial residue-biochar composite)

[0169] (1) Formulation composition (percentage by mass)

[0170] Organic carriers account for 65%, including:

[0171] Fungal residue-biochar composite: 60% (fungal residue:biochar = 1:2)

[0172] Well-rotted straw compost: 5% (phenolic acid content 3.8 μg / g)

[0173] Inorganic excipients account for 30%, including:

[0174] Vermiculite: 15% (particle size 4mm, bulk density 0.15g / cm³) 3 )

[0175] Perlite: 10% (3mm grain size, EC 0.3mS / cm)

[0176] Thermosensitive gel microspheres: 3% (acrylic acid-chitosan copolymer microspheres, particle size 0.5-1mm, phase change temperature 18℃, water holding capacity ≥400%)

[0177] Palaequa calcite powder: 2% (200 mesh, pH buffering capacity ≥50mmol / kg)

[0178] Nutritional and biological regulators 5%, including:

[0179] Slow-release nutrient pack: 4%; composed of sulfur-coated urea, ammonium polyphosphate, and potassium humate. The mass ratio of N in the sulfur-coated urea: P2O5 in the ammonium polyphosphate: K2O in the potassium humate is 20-10-25. Sulfur-coated urea: particle size 1-2mm, coating thickness 10-15μm; ammonium polyphosphate: water solubility ≤5%; potassium humate: chelated potassium. The slow-release nutrient pack has a release period of 30-40 days, matching the seedling growth curve.

[0180] Microbial inoculant: 1%; composition of Trichoderma harzianum T-22, Bacillus subtilis BS-208 and Bacillus mucilaginosus in a volume ratio of 1:1:1, with Trichoderma harzianum T-22 1×10 8 CFU / g, Bacillus subtilis BS-208 5×10 7 CFU / g

[0181] (2) Preparation and application refer to Example 1.

[0182] (3) Test Results

[0183] 1. Comparison of seedling performance (test period: 30 days)

[0184]

[0185] 2. Nutrient utilization and slow-release effect

[0186]

[0187] 3. Environmental adaptability and reusability

[0188]

[0189] Example 3: Low-cost formulation (40% of the microbial residue-biochar composite)

[0190] (1) Formulation composition (percentage by mass)

[0191] Organic carrier module 50%, including:

[0192] Fungal residue-biochar composite: 40% (fungal residue:biochar = 1:1)

[0193] Well-rotted straw compost: 10% (phenolic acid content 5.0 μg / g)

[0194] Inorganic auxiliary material module 45%, including:

[0195] Vermiculite: 20% (particle size 4mm, bulk density 0.15g / cm³) 3 )

[0196] Perlite: 15% (EC 0.5mS / cm)

[0197] Thermosensitive gel microspheres: 7% (0.5-1mm)

[0198] Palaequa calcite powder: 3% (200 mesh, pH buffering capacity ≥50mmol / kg)

[0199] The Nutrition and Biological Regulation module comprises 5%, including:

[0200] Slow-release nutrient pack: 3%; composition includes sulfur-coated urea, ammonium polyphosphate, and potassium humate. The mass ratio of N in the sulfur-coated urea: P2O5 in the ammonium polyphosphate: K2O in the potassium humate is 15-15-18. Sulfur-coated urea: particle size 1-2 mm, coating thickness 10-15 μm; ammonium polyphosphate: water solubility ≤5%; potassium humate: chelated potassium. The slow-release nutrient pack has a release period of 30-40 days, matching the seedling growth curve.

[0201] Microbial inoculant: 2%, composed of Trichoderma harzianum T-22, Bacillus subtilis BS-208 and Bacillus mucilaginosus in a volume ratio of 1:1:1.

[0202] (2) Preparation and application are as described in Example 1. The thermosensitive gel is omitted in this example: it is suitable for warm regions (ambient temperature > 15°C).

[0203] Comparative Example 1

[0204] A traditional substrate of peat moss:vermiculite:perlite = 6:2:2 was used as a comparison.

[0205] Comparative Example 2

[0206] Compared to Example 1, the slow-release nutrient pack was omitted, while all other aspects were the same as in Example 1.

[0207] Comparative Example 3

[0208] Compared to Example 1, the biological regulator was omitted, while all other aspects were the same as in Example 1.

[0209] Performance comparison of each example

[0210]

[0211] Low temperature test example:

[0212] The germination of seedlings in early spring under low temperature conditions was tested in Example 2 and the traditional substrate, and the rest were the same as in Example 1.

[0213] Using the substrate of Example 2, under early spring low-temperature conditions (day / night temperatures of 12℃ / 5℃), the germination rate was still >92%, the root zone temperature was 14±1.5℃, and the seedling period was 18 days. In contrast, under the traditional substrate low-temperature conditions (5℃), the germination rate was 62%, the root zone temperature was 10.3±3.5℃, and the seedling period was 25 days. Compared to the traditional substrate, the substrate of Example 2 increased the number of lateral roots by 52% and the root dry weight by 45.6%.

[0214] Example 2: The substrate maintained a porosity >70% even after 3 years of continuous cropping, and the available phosphorus content in the substrate remained ≥25 mg / kg (initial value 35 mg / kg). In contrast, traditional substrates suffered severe caking after a single use, with the available phosphorus content dropping to ≤8 mg / kg, making them unusable.

[0215] Example 2 shows that the cost of the substrate is around 420 yuan / ton, with an average annual cost of 320 yuan per mu; while the cost of the traditional substrate is around 680 yuan / ton, with an average annual cost of 800 yuan per mu.

[0216] This invention is the world's first integrated slow-release nutrient, biological control, and temperature-controlled buffering substrate specifically designed for rapeseed seedling cultivation. It achieves a green seedling cultivation model characterized by "zero peat, low salinity, and high circulation," meeting EU ecological certification standards (EC 834 / 2007). Using this substrate shortens the rapeseed seedling order delivery cycle by more than 5 days, and reduces the customer complaint rate (weak seedlings, diseased seedlings) from 15% to less than 1%. A 500-mu (approximately 33 hectares) seedling field can save 160,000 yuan in costs and increase income by 240,000 yuan annually.

Claims

1. A reusable, peat-free substrate for rapeseed seedling cultivation, characterized in that: It includes 50-65% organic carrier, 30-45% inorganic excipients, and 5-7% nutrients and bioregulators; the 50-65%, 30-45%, and 5-7% are all mass percentages. The nutrient and biological regulator consists of a slow-release nutrient pack and a microbial agent in a mass ratio of (3~5):(1~2); The slow-release nutrient pack includes sulfur-coated urea, ammonium polyphosphate, and potassium humate; the mass ratio of N in sulfur-coated urea, P2O5 in ammonium polyphosphate, and K2O in potassium humate is (15~20):(10~15):(18~25), and the coating thickness of sulfur-coated urea is 10-15 μm. The bioregulator is composed of Trichoderma harzianum T-22, Bacillus subtilis BS-208 and Bacillus mucilaginosus, with a volume ratio of 1:1: (0.5~1). The inorganic excipients contain functional additives, which are composed of thermosensitive gel microspheres and palygorskite powder in a mass ratio of (2~3):(1~2); wherein the thermosensitive gel microspheres are acrylic acid-chitosan copolymer microspheres with a particle size of 0.5-1 mm, a phase change temperature of 15-25℃, and a water holding capacity of ≥400%; The organic carrier consists of a microbial residue-biochar composite and well-rotted straw compost in a mass ratio of (40~60):(5~10); the microbial residue-biochar composite is a mixture of fermented microbial residue and rice husk char in a mass ratio of 1:(1~2), with a moisture content ≤10%. The preparation method of the fungal residue-biochar composite includes the following steps: 1) Crushing and conditioning of mushroom residue: Fresh edible fungus cultivation waste is crushed to a particle size ≤5 mm and the moisture content is adjusted to 55-60% to obtain fungal residue. 2) Directional fermentation: Microbial agent addition: Inoculate the substrate with cellulose-decomposing bacteria at a rate of 0.5-1 wt%; wherein the cellulose-decomposing bacteria are Trichoderma viride and Bacillus licheniformis in a volume ratio of 1:

2. Fermentation conditions: Temperature 55-60℃, maintained for 5-7 days, turning the pile every 24 hours to obtain fermented residue; premix 0.2wt% of Bacillus mucilaginosus spore powder into the fermented residue; 3) Biochar composite: The fungal residue obtained in step 2) is mixed with rice husk charcoal at a mass ratio of 1:(1~2), and dried at 50~60℃ until the moisture content is ≤10% to form a fungal residue-biochar composite.

2. The reusable peat-free rapeseed seedling substrate according to claim 1, characterized in that: Palaequa calcite powder: particle size 150~200 mesh, pH buffering capacity ≥50 mmol / kg.

3. The reusable peat-free rapeseed seedling substrate according to claim 1 or 2, characterized in that: The inorganic excipients consist of expanded vermiculite, perlite, and functional additives in a mass ratio of (15~25):(10~15):(3~5).

4. The reusable peat-free rapeseed seedling substrate according to claim 3, characterized in that: Expanded vermiculite, particle size 3-6 mm, bulk density 0.1-0.2 g / cm³, porosity ≥80%; perlite, particle size 2-4 mm, pre-washed to EC value ≤0.5 mS / cm, where EC is electrical conductivity.

5. The reusable peat-free rapeseed seedling substrate according to claim 4, characterized in that: The C / N ratio of the fermentation residue is 25-30; the specific surface area of ​​rice husk charcoal is ≥200 m² / g, and the porosity is ≥80%; the phenolic acid content in the decomposed straw compost is ≤5 μg / g, and the cellulose degradation rate is ≥85%.

6. The reusable peat-free rapeseed seedling substrate according to claim 5, characterized in that: The raw materials used for composting decomposed straw are a mixture of wheat straw and chicken manure with a C / N ratio of 25 to 28:

1.

7. The reusable peat-free rapeseed seedling substrate according to claim 6, characterized in that: The preparation method of well-rotted straw compost includes the following steps: 1) Raw material pretreatment: Cut wheat straw into 3-5 cm sections and mix it with chicken manure at a C / N ratio of 25-28:1, adjusting the initial moisture content to 60-65%. 2) High-temperature fermentation: Phase 1: Add 0.2 wt% EM bacteria and 0.1 wt% white rot fungi based on the weight of wheat straw, and maintain at 40-50℃ for 3 days; Phase 2: Maintain 55-65℃ for 10-12 days, turning the pile daily; Phase 3: Maintain 40-45℃ for 7 days, and spray with lime water to adjust the pH to 6.5-7.0; 3) Screening: Undegraded coarse fibers are removed by passing through a 10-mesh sieve, and the phenolic acid content is ≤5 μg / g.

8. A method for preparing a reusable peat-free rapeseed seedling substrate according to claim 7, characterized in that: Includes the following steps: 1) Add the expanded vermiculite and perlite from the organic carrier and inorganic auxiliary materials into a twin-shaft mixer in proportion, and mix for 15-20 minutes at a speed of 20-25 rpm; 2) Under the condition of temperature ≤40℃, add the slow-release nutrient pack, the mixture of Trichoderma harzianum T-22 and Bacillus subtilis BS-208, the temperature-sensitive gel microspheres, Bacillus thuringiensis and palygorskite powder in stages. Except for Bacillus thuringiensis, after adding the previous material, stir at 20-25 rpm for 3-5 minutes before adding the next material. After adding Bacillus thuringiensis, stir at 15-20 rpm for 1-3 minutes. Add palygorskite powder and stir at 20-25 rpm for 5-8 minutes to obtain the mixed matrix. 3) Spray the mixed matrix with a concentration of 0.1 mol / L citrate-potassium dihydrogen phosphate buffer to adjust the matrix pH to 6.0-6.5; then add deionized water or humic acid solution to control the initial EC value at 1.2-1.5 mS / cm. 4) Fumigating with ozone at a concentration of 50-80 ppm for 2-3 hours can inactivate residual pathogens; 5) The moisture content should be controlled at 30-35%, vacuum packaged in bags of 5-10 L each, stored at a temperature of ≤25℃, and have a shelf life of ≥6 months.

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