Method for preparing blueberry culture medium by fermenting pruned branches of fruit trees with compound bacteria

Abstract

The invention relates to a method for fermenting pruned fruit tree branches by using compound bacteria and preparing a blueberry culture medium. The method comprises the following steps: (1) activating bacterial strains; (2) preparing a compound bacteria agent; (3) preparing a modified attapulgite carrier; according to the method, orchard pruning waste can be fully utilized and turned into wealth, and environmental pollution caused by improper treatment of fruit tree pruning branches is avoided. Compared with a conventional substrate, the soil bulk density of the culture substrate is reduced by 10%-12%, the total porosity is improved by 12%-20%, the soil permeability is good, growth of blueberries is better facilitated, and the culture substrate is suitable for large-area popularization.

Description

Technical Field

[0001] This invention belongs to the field of agricultural waste resource utilization and fruit tree cultivation technology, specifically involving a method for fermenting fruit tree pruning branches using compound bacteria and further preparing a blueberry-specific cultivation substrate. Background Technology

[0002] my country has a vast orchard area, and the total amount of branches produced by fruit tree pruning reaches millions of tons every year. These pruned branches are rich in cellulose, hemicellulose, lignin, and various nutrients, making them a valuable biomass resource. However, the current methods of disposing of fruit tree pruned branches are mostly on-site burning, indiscriminate discarding, or simple landfilling. This not only causes serious waste of resources but also easily leads to environmental pollution and the spread of pests and diseases, which violates the concept of green and circular agricultural development.

[0003] Composting is an effective way to utilize agricultural waste, but fruit tree pruning branches have a high lignocellulose content and are difficult to degrade. Fermentation with a single strain or ordinary inoculant has drawbacks such as a long maturation period, low degradation efficiency, and unbalanced nutrient content in compost products, which restricts its resource utilization efficiency. Research shows that by producing a compound inoculant using our team's own preserved Saccharomyces cerevisiae and Lactobacillus fermentum, the synergistic effect can significantly improve the lignocellulose degradation capacity, accelerate the composting process, and increase the nutrient content and microbial activity of compost products. The degradation effect on lignocellulose in fruit branches is significantly better than that of a single inoculation method.

[0004] Blueberries, as typical acid-loving plants, have stringent requirements for their cultivation substrate, needing a pH of 4.0-5.5, high organic matter content, loose and well-aerated structure, and good water and fertilizer retention. Currently, blueberry cultivation substrates are mainly composed of peat, coconut coir, and pine bark. Among these, peat is a non-renewable resource, and long-term over-exploitation will damage the ecological environment and result in high costs. A single substrate material cannot simultaneously meet the physical, chemical, and nutrient requirements of blueberries, easily leading to poor root development and reduced yield and quality. Furthermore, the production process requires vinegar residue or sulfur for acidification, resulting in high production costs and environmental pollution risks.

[0005] Based on this, fruit tree pruning branches are fermented with a compound microbial culture to transform them into high-quality organic raw materials. The fermentation is terminated at a pH of 5.0-5.5, significantly reducing the acidification cost of blueberry cultivation. Combined with suitable auxiliary materials, a blueberry cultivation substrate is prepared, achieving resource recycling of agricultural waste, replacing some peat resources, reducing blueberry cultivation costs, and meeting the growth requirements of blueberries, thus possessing significant economic, ecological, and social benefits. Currently, there is no mature technology combining the fermentation of fruit tree pruning branches with compound microbial culture and the preparation of a dedicated blueberry substrate; therefore, there is an urgent need to develop a technologically sound and stable method. Summary of the Invention

[0006] To address the problems of extensive processing of fruit tree pruning branches, high cost of blueberry cultivation substrates that rely on non-renewable resources, and low fermentation efficiency of fruit branches, this invention provides a method for fermenting fruit tree pruning branches using compound bacteria and preparing blueberry cultivation substrates. This method achieves efficient resource utilization of fruit tree pruning branches, produces high-quality cultivation substrates suitable for blueberry growth, and balances environmental protection and practicality.

[0007] To achieve the above objectives, this invention discloses a method for fermenting fruit tree pruning branches using compound bacteria and preparing a blueberry cultivation substrate, characterized by the following steps: Step 1: Preparation of Compound Microbial Agent (1) Strain screening and activation: Select Saccharomyces cerevisiae (Saccharomyces cerevisiae) Saccharomyces cerevisiae The strain, *Lactobacillus fermentum*, was deposited by the applicant with accession number CGMCC NO.33774, at the China General Microbiological Culture Collection Center (CGMCC) on March 10, 2025, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. Lactobacillus fermentum The strain, deposited by the applicant under accession number CGMCC NO.36375, with the same depositary institution and address as described above, and deposited on October 28, 2025, was used. The yeast and Lactobacillus fermentum were inoculated into YPD medium and cultured at 25-30℃ with shaking at 120-150 rpm for 20-24 h, until the viable count reached 2.0 × 10⁻⁶. 8 -5.0×10 8 CFU / ml; the above-mentioned *Lactobacillus plantarum* was inoculated into MRS medium and incubated statically at 30-34℃ for 24 h to activate the viable count to 5.0 × 10⁻⁶. 8 -8.0×10 8 CFU / ml.

[0008] (2) Preparation of compound microbial agent: Prepare compound fermentation medium, which by mass percentage is molasses 2.0-2.5%, yeast extract 0.6-0.8%, sodium acetate 0.4-0.5%, diammonium hydrogen citrate 0.15-0.2%, tomato juice 5-8%, potassium dihydrogen phosphate 0.2%, manganese sulfate 0.015-0.02%, pH adjusted to 6.0, sterilized at 115 ℃ for 20 min; mix the two activated bacterial solutions at a volume ratio of 1:2-1:3, inoculate at 1.5-3% of the fermentation medium volume, and ferment in a deep layer at 28-31 ℃ and 100-120 rpm for 18-24 h, until the pH of the system is 4.0-4.5.

[0009] (3) Preparation of modified attapulgite carrier: attapulgite was purified and impurities removed, crushed and passed through a 200-mesh sieve, soaked in a 2-3% dilute hydrochloric acid solution for 3 h, stirred at a rate of 50 r / min, and neutralized to pH 6.5-7.0; then dried at 105℃ to constant weight, ultrasonically treated for 20 min to break up the rod crystal bundles, sterilized by high-pressure steam at 121℃ for 30 min, and cooled for later use. The specific surface area of ​​the modified attapulgite was increased to 180-220 m² / g, which enhanced its adsorption and fixation capacity.

[0010] (4) Assembly of the compound microbial system: Mix the compound microbial agent with the modified attapulgite soil at a mass ratio of 1:2, stir evenly, add lignin peroxidase, stir and adsorb at a constant temperature of 25 ℃ for 1-2 h, let stand for 30 min, so that the microorganisms can fully attach to the pores of the attapulgite soil.

[0011] (5) Low-temperature drying: Spread the adsorbed mixture evenly (thickness <1cm) and place it in a vacuum drying oven or forced-air drying oven at 30-35℃ until the moisture content drops to 8-12% and the bacterial agent concentration is ≥1×10 8 CFU / ml.

[0012] (6) Crushing and sieving: After drying, crush and sieve through an 80-mesh sieve to obtain powdered attapulgite soil fungicide. (7) Stability test: After storage at room temperature for 3 months, the number of viable bacteria should be retested and the survival rate should be ≥ 60%.

[0013] (1) Winter pruning: Prune the one-year-old branches of the fruit trees in winter to branches with a length of 30-200 cm and a cross-sectional diameter of 0.3-2.0 cm; (2) Crushing: Use a crusher to crush the pruned branches. To improve fermentation efficiency and reduce dust, the volume of the crushed branches should be 0.5-3.0 cm³. 3 The shredded branches should have good longitudinal cutting or breaking to increase the surface area of ​​the shredded branches; (3) Adjust the fermentation environment: Use urea to adjust the C:N ratio to 25-30:1 and adjust the moisture content to 10%-20%.

[0014] (1) Inoculate the compound microecological agent from step one into the grape pruning waste after pretreatment in step two at an inoculation rate of 1%-5% of the dry weight of the crushed branches, mix evenly, and then compost in windrows or troughs.

[0015] (2) Pile: Pile the crushed branches into a single pile with a volume ≥ 2 m³. 2 The weight of a single pile should be ≥500 kg. Note that the height of the pile should not exceed 2 m, otherwise the bottom will be easily compacted and oxygen-deficient, leading to anaerobic putrefaction.

[0016] (3) Control the temperature of the pile at 55-65℃ for 5-7 days, then let it cool naturally to room temperature. The fermentation cycle is 35-40 days. Ferment until the temperature of the pile drops to room temperature, the material is dark brown, soft and odorless, the carbon-nitrogen ratio is ≤20:1, and the seed germination index is ≥85%. Then the decomposed fermented material can be added to the blueberry cultivation substrate.

[0017] The blueberry cultivation substrate is prepared by mixing 40%-50% fermented decomposed fruit branches, 20%-30% peat, 10%-15% coconut coir, 10%-15% perlite, and 5%-10% vermiculite by volume, adjusting the pH to 4.0-5.5, and stirring thoroughly. The compound microbial preparation contains *Saccharomyces cerevisiae* at a ratio of 1:2-1:3 to *Lactobacillus fermentum*. The coconut coir is treated with calcium nitrate solution before use, with an EC value controlled at <0.8 mS / cm. The bulk density is 0.7-0.9 g / cm³, total porosity is ≥60%, and organic matter content is ≥40%.

[0018] This invention further discloses a method for fermenting fruit tree pruning branches using compound bacteria and preparing blueberry cultivation substrate, which aims to improve soil permeability. Blueberries prefer loose soil, with a suitable bulk density generally around 0.8-1.0 g / cm³. Experimental results show that: The blueberry cultivation substrate prepared by fermenting fruit tree pruning and crushing branches with this compound bacteria can significantly improve soil porosity and aeration and water permeability. The soil bulk density is reduced by 10%-12% compared with conventional substrates, and the total porosity is increased by 15%-20%. The substrate's water retention and fertilizer retention capacity and aeration are synergistically improved. After planting, the plant height and root fresh weight are increased by 18% and 22% respectively compared with the traditional substrate group. At the same time, the beneficial microbial community structure in the substrate is richer, which can effectively improve the rhizosphere microenvironment and promote the absorption of nutrients by blueberry plants. The survival rate of seedlings after planting reaches 96.7%, which is not significantly different from the survival rate of planting with conventional substrates.

[0019] The advantages of this invention, which discloses a method for fermenting fruit tree pruning branches using compound bacteria and preparing blueberry cultivation substrate, compared with existing technologies, are as follows: Resource recycling and efficient utilization: This invention uses agricultural waste such as fruit tree pruning branches as the core raw material, which is transformed into high-quality organic materials through compound bacterial fermentation. This completely solves the environmental problems caused by the random discarding and burning of fruit branches, and realizes a closed-loop cycle of "waste-organic raw materials-cultivation substrate", significantly improving the resource utilization rate.

[0020] Superior fermentation efficiency and quality: The synergistic effect of our own preserved brewing yeast and fermenting lactic acid bacteria significantly improves the degradation efficiency of lignocellulose, with cellulose and hemicellulose degradation rates reaching over 45% and 50% respectively, shortening the fermentation cycle by 30%-40% compared to single-agent fermentation. At the same time, the fermentation material is rich in nutrients, with an organic matter content of ≥40% and a significant increase in the number of beneficial microorganisms, providing sufficient nutrition for blueberry growth.

[0021] Suitable for blueberry growth requirements: The prepared blueberry cultivation substrate has a stable pH value of 4.0-5.5, a bulk density of 0.7-0.9 g / cm³, and a total porosity of ≥60%, which combines good air permeability, water retention and fertilizer retention, and matches the growth characteristics of blueberries that prefer acid and loose soil. The fermented decomposed fruit branches in the substrate replace part of the peat resources, reducing the substrate cost by more than 30%, while avoiding the damage to the ecological environment caused by peat mining.

[0022] The process is simple and easy to promote: The fermentation and substrate preparation process of this invention is clear, and the required equipment is all conventional agricultural production equipment (branch crusher, mixer, etc.). It is easy to operate, the cost is controllable, and it can be applied to large-scale applications in orchards, agricultural cooperatives and substrate production enterprises, and has broad market prospects.

[0023] Significant ecological and economic benefits: The fermentation process produces no secondary pollution, and the use of the substrate can improve the physical and chemical properties of the soil, enhance soil microbial activity and organic matter content; the cultivated blueberries have well-developed root systems and grow vigorously, with a yield 15%-20% higher than that of traditional substrate cultivation, and the quality (sugar content, anthocyanin content) is not significantly different from that of conventional substrate cultivation, thus balancing ecological and economic benefits. Detailed Implementation

[0024] The present invention will now be described through specific embodiments. Unless otherwise specified, all technical means used in this invention are methods well known to those skilled in the art. Furthermore, the embodiments should be understood as illustrative, not limiting the scope of the invention; the essence and scope of the invention are defined only by the claims. For those skilled in the art, various changes or modifications to the material composition and dosage in these embodiments without departing from the essence and scope of the invention are also within the scope of protection of this invention. The brewing yeast and lactobacillus fermentum used in this invention are proprietary strains; other raw materials and reagents are commercially available. Example

[0025] Fermenting fruit tree branches with compound bacterial enzymes Raw material pretreatment: Collect 500 kg of apple orchard pruned branches, remove diseased and insect-infested branches and impurities, then crush them into 1-2 cm pieces using a branch shredder, and dry them until the moisture content is 40% for later use.

[0026] Preparation of compound bacterial enzyme preparation: The compound bacterial agent was inoculated into LB fermentation medium and cultured at 30℃ and 160 r / min for 60 h to prepare a bacterial solution with a concentration of 5×10⁻⁶. 8 CFU / mL of bacterial agent stock solution; take 10 kg of bacterial agent stock solution, add 1.5 kg of cellulase, 1 kg of laccase, and 0.5 kg of manganese peroxidase, stir evenly to obtain 13 kg of compound bacterial enzyme preparation.

[0027] Fermentation material preparation: 500 kg of pretreated apple branch debris was used as the main material, 80 kg of decomposed pig manure was added (mass ratio of main material to nitrogen-rich material was 6.25:1), 1.5 kg of urea and 3 kg of ammonium bicarbonate were added (total amount of conditioner added was 0.9%), and water was sprayed to adjust the moisture content to 60%. The carbon-nitrogen ratio was tested to be 28:1.

[0028] Aerobic fermentation: The prepared materials are piled into trapezoidal stacks with a base width of 2.5m and a height of 1.8m. 1.5kg of compound bacterial enzyme preparation is sprayed evenly and covered with a breathable and waterproof cloth. On the third day of fermentation, the temperature of the pile rises to 58℃ and is maintained at a high temperature for 18 days. During this period, the pile is turned over 3 times on the 7th, 14th and 22nd days. When turning the pile, clean water is added to maintain a moisture content of 60%. On the 40th day of fermentation, the temperature of the pile drops to room temperature. The material is dark brown, loose and odorless. The seed germination index is 78% and the moisture content is 28%. Fermentation is completed and 420kg of decomposed fruit branch fermented material is obtained. Example

[0029] Preparation of blueberry cultivation substrate Substrate raw material ratio: Take 45 kg of decomposed fruit branch fermentation material prepared in Example 1, 25 kg of high-level peat, 12 kg of treated coconut coir, 10 kg of perlite, and 8 kg of vermiculite for later use.

[0030] Mixing and conditioning: Put the above raw materials into a mixer and stir for 5 minutes. Add 5% citric acid solution to adjust the pH value to 4.8. Spray low EC nutrient solution (EC=0.6mS / cm) to adjust the water content to 50%. Continue stirring for 12 minutes to make the mixture uniform.

[0031] Sterilization and maturation: Place the prepared substrate in a sealed space and sterilize it with 75℃ high-temperature steam for 2 hours. After naturally cooling to room temperature, ventilate and mature it for 4 days, turning it once a day to obtain 100kg of blueberry cultivation substrate.

[0032] Example 3 Fermented fruit tree branches were used as a substrate additive for blueberry planting. strawberry seedling pretreatment Variety selection: Choose varieties with well-developed root systems, free from pests and diseases, and with a plant height ≥20cm. 2 Annual blueberry container seedlings.

[0033] Root treatment: Remove the seedlings from the seedling container, gently shake off the loose substrate around the roots, and trim off any rotten or excessively long roots (retaining a root length of 10-15cm). Soak the roots in an 800-fold dilution of 50% carbendazim wettable powder for 5-10 minutes, then remove and air dry for 10-15 minutes before use.

[0034] Planting methods (1) Selection of planting time Choose to plant before spring budding (March-April), avoiding periods of high temperature and direct sunlight and low temperature and frost; the best time to plant is on a cloudy day or in the evening to reduce the evaporation of seedling moisture.

[0035] (2) Planting preparation Choose a flowerpot or root control device with a diameter of 30-40cm and drainage holes at the bottom.

[0036] (3) Planting operation Place the pretreated blueberry seedlings in the center of the container, ensuring the roots are spread out and the grafting point is 2-3 cm above the substrate surface to prevent rotting. Fill the area around the roots with blueberry-specific cultivation substrate layer by layer, gently lifting the seedling to ensure close contact between the substrate and the roots. Once the substrate is level with the original soil mark on the seedling, gently compact the surface.

[0037] (4) Post-planting management Watering to settle the roots: Immediately after planting, water thoroughly until the substrate is completely saturated and water seeps out from the bottom of the container. After that, water once every 2-3 days to keep the substrate moisture content at 40-50% for 15-20 days.

[0038] Shading and protection: After planting, set up a shade net (50% shading rate) to avoid direct sunlight; after 1 month, gradually remove the shade net to allow the seedlings to adapt to the natural light environment.

[0039] Covering to retain moisture: 10 days after transplanting, cover the substrate surface with 2-3cm of pine needles or sawdust to reduce the rate of water evaporation and inhibit weed growth. Example

[0040] Screening for the optimal carbon-nitrogen ratio: Five treatments with carbon-nitrogen ratios of 15, 20, 25, 30, and 35 were set. The total organic carbon and total nitrogen of the samples after fermentation were measured, as well as the organic carbon, total nitrogen, urease, acid phosphatase, and sucrase levels 60 days after fermentation. The carbon-nitrogen ratio and T-value (final T / N / initial T / N) were calculated. Treatments with carbon-nitrogen ratios of 25 and 30 showed better performance and the highest cost-effectiveness. Table 1 shows that the initial carbon-nitrogen ratio of the crushed branches was not significantly different from the set ratios, while the final carbon-nitrogen ratios showed more significant differences. Generally, treatments with lower carbon-nitrogen ratios had lower final values, and treatments with higher ratios had higher final values. When calculating the T-value, only treatments with carbon-nitrogen ratios of 25 and 30 had values ​​below 0.6. A value below 0.6 is generally considered an indicator of complete decomposition and also has some reference value for checking urease activity, acid phosphatase activity, and sucrase activity (Table 1).

[0041]

[0042] Example 5 Screening for optimal moisture content: Five treatments were set up with crushed vine branches containing moisture contents of 5%, 10%, 15%, 20%, and 25%. For each treatment, the total organic carbon and total nitrogen were measured after fermentation, and the organic carbon, total nitrogen, urease, acid phosphatase, and sucrase levels were measured after 60 days of fermentation. The carbon-to-nitrogen ratio and T-value (final T / N value / initial T / N value) were calculated. Table 3 shows that different concentrations of organic composting agents did not significantly affect the initial T / N value, the final T / N value, or the T-value for vine branches with 10%-25% moisture content. After 60 days of composting, the T-values ​​of the grape vine waste were all less than 0.8, significantly higher than the 5% treatment, but all were less than 0.6. This indicates that simply adjusting the vine moisture content cannot promote vine composting. The differences in urease activity, acid phosphatase activity, and sucrase activity were not significant. From the perspective of labor cost control, we believe that controlling the moisture content of branches at low concentrations of 10%, 15%, and 20% has a certain effect on the decomposition of branches (Table 2).

[0043]

[0044] Effect verification A comparative experiment was conducted between the blueberry cultivation substrate prepared in this embodiment and a traditional substrate (peat:coconut coir:perlite = 5:2.5:2.5). Blueberry seedlings of the same variety were planted in both groups, with 30 seedlings per group, and managed using conventional methods. The results showed that the survival rate of blueberry seedlings in the substrate-grown group was 96.7%, which was not different from the traditional substrate group. After 3 months of growth, the plant height and root fresh weight increased by 18.2% and 22.5%, respectively, compared to the traditional substrate group. There were no significant differences in fruit sugar content and anthocyanin content between the two substrates. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of the present invention, and all such modifications and modifications shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for fermenting fruit tree pruning branches using compound bacteria and preparing blueberry cultivation substrate, characterized in that, According to Next steps: Step 1: Preparation of Compound Microbial Agent (1) Strain activation: Select Saccharomyces cerevisiae (Saccharomyces cerevisiae) Saccharomyces cerevisiae ) strains and Lactobacillus fermentum ( Lactobacillus fermentum The above-mentioned yeast and Lactobacillus fermentum strains were inoculated into YPD medium and cultured at 25-30℃ with shaking at 120-50 rpm for 20-24 h until the viable count reached 2.0 × 10⁻⁶. 8 -5.0×10 8 CFU / ml; inoculate the above-mentioned *Lactobacillus plantarum* into MRS medium and incubate statically at 30-34℃ for 24 h to activate to a viable count of 5.0 × 10⁻⁶. 8 -8.0×10 8 CFU / ml; (2) Preparation of compound microbial agent: Prepare compound fermentation medium, which by mass percentage is molasses 2.0-2.5%, yeast extract 0.6-0.8%, sodium acetate 0.4-0.5%, diammonium hydrogen citrate 0.15-0.2%, tomato juice 5-8%, potassium dihydrogen phosphate 0.2%, manganese sulfate 0.015-0.02%, pH adjusted to 6.0, sterilized at 115 ℃ for 20 min; mix the two activated bacterial solutions at a volume ratio of 1:2-1:3, inoculate at 1.5-3% of the fermentation medium volume, and ferment in a deep layer at 28-31 ℃ and 100-120 rpm for 18-24 h, until the pH of the system reaches 4.0-4.5; (3) Preparation of modified attapulgite carrier: attapulgite is purified and impurities are removed, crushed and passed through a 200-mesh sieve, soaked in a 2-3% dilute hydrochloric acid solution for 3 h, stirred at a rate of 50 r / min, and neutralized to pH 6.5-7.0; then dried at 105℃ to constant weight, ultrasonically treated for 20 min to break up the rod crystal bundles, sterilized by high-pressure steam at 121℃ for 30 min, and cooled for later use; (4) Assembly of the compound microbial system: Mix the compound microbial agent with modified attapulgite soil at a mass ratio of 1:2, stir evenly, add lignin peroxidase, stir and adsorb at a constant temperature of 25℃ for 1-2 h, let stand for 30 min to allow the microorganisms to fully adhere to the pores of the attapulgite soil; Low-temperature drying: Spread the adsorbed mixture evenly with a thickness of < 1 cm, place it in a vacuum drying oven or forced-air drying oven at 30-35℃ and dry until the moisture content drops to 8-12% and the microbial agent concentration is ≥1×10 8 CFU / ml; Pulverization and sieving: After drying, pulverize and pass through an 80-mesh sieve to obtain powdered attapulgite soil fungicide; (5) Stability test: After storage at room temperature for 3 months, the number of viable bacteria should be retested, and the survival rate should be ≥ 60%; Step Two: Treatment of Fruit Tree Pruning Branches (1) Winter pruning: Prune the one-year-old branches of the fruit trees in winter to branches with a length of 30-200 cm and a cross-sectional diameter of 0.3-2.0 cm; (2) Shredding: Use a shredder to shred the pruned branches. The volume of the shredded branches should be 0.5-3.0 cm3. The shredded branches should have good longitudinal cutting or breaking. (3) Adjust the fermentation environment: Use urea to adjust the C:N ratio to 25-30:1 and adjust the moisture content to 10%-20%; Step 3: Ferment and decompose the pruned branches of the fruit trees. (1) Inoculate the compound microecological agent of step one into the grape pruning waste after pretreatment in step two at an inoculation amount of 1%-5% of the dry weight of the crushed branches, mix evenly and then compost in windrows or troughs. (2) Pile: Pile the crushed branches into a single pile with a volume ≥ 2 m³. 2 The weight of a single pile is ≥500 kg, and the height of the pile is 2 m; (3) Control the temperature of the pile at 55-65℃ for 5-7 days, then let it cool naturally to room temperature. The fermentation cycle is 35-40 days. Ferment until the pile temperature drops to room temperature, the carbon-nitrogen ratio is ≤20:1, and the seed germination index is ≥85%. Then the decomposed fermented material is obtained and blueberry cultivation substrate is added. Step 4: Mixing Blueberry Cultivation Substrate Materials The blueberry cultivation substrate is prepared by mixing 40%-50% fermented fruit branches, 20%-30% peat, 10%-15% coconut coir, 10%-15% perlite, and 5%-10% vermiculite by volume, adjusting the pH to 4.0-5.5, and stirring evenly.

2. The method according to claim 1, characterized in that, In the compound microbial preparation, the ratio of strains is Saccharomyces cerevisiae:Lactobacillus fermentum = 1:2-1:

3.

3. The method according to claim 1, characterized in that, The coconut coir is soaked in calcium nitrate solution before use, and the EC value is controlled to be <0.8mS / cm.

4. The blueberry cultivation substrate prepared by the method of claim 1, characterized in that, Bulk density 0.7-0.9 g / cm³, total porosity ≥60%, organic matter content ≥40%.

5. The method of fermenting fruit tree pruning branches using compound bacteria and preparing blueberry cultivation substrate as described in claim 1 is used to improve soil permeability and promote blueberry growth.

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