A seedling substrate and its preparation method

Abstract

This invention discloses a rice seedling substrate and its preparation method, belonging to the technical field of rice seedling substrates. The substrate is composed of decomposed rice straw, crayfish by-product shrimp powder, fermented livestock manure, special nutrient soil, pH regulator, water-retaining and binding agent, and microbial compound inoculant in a specific ratio. During preparation, each organic raw material undergoes a harmless pretreatment process, followed by graded mixing, inoculant activation and blending, and aging. This invention replaces a large amount of natural nutrient soil with agricultural and aquatic waste, resulting in a balanced nutrient ratio, stable granular structure, and good synergistic effects of water retention, fertilizer retention, and aeration. It significantly promotes seedling root growth and enhances resistance to stress and disease, making it suitable for both machine transplanting and manual rice seedling raising.

Description

Technical Field

[0001] This invention belongs to the field of rice seedling substrate technology, specifically relating to a seedling substrate and its preparation method. Background Technology

[0002] Seedling raising is a crucial step in rice production, as the quality of the seedlings directly determines the number of tillers, yield, and overall quality of the rice. The seedling substrate, as the core carrier for seedling growth, is fundamental to cultivating strong seedlings due to its physicochemical properties, nutrient supply capacity, granular structure stability, and water and fertilizer retention and aeration performance. Currently, rice seedling raising in China still largely relies on mature topsoil as the main substrate material. Extensive extraction of topsoil from farmland not only damages the topsoil and leads to soil fertility loss, but also results in natural topsoil having limited nutrient content and poor synergy between water and fertilizer retention and aeration / water permeability. This necessitates frequent application of chemical fertilizers and fungicides during seedling raising, increasing production costs and easily causing substrate compaction, salinization, and soil-borne diseases, leading to weak seedling roots, low seedling survival rate, and prolonged transplanting recovery period.

[0003] Meanwhile, my country generates a large amount of agricultural and aquatic product processing waste every year. The annual output of rice straw is enormous; traditional incineration severely pollutes the atmosphere, while indiscriminate dumping leads to mold, rot, and the breeding of bacteria and insect eggs. Byproducts from crayfish processing, such as shrimp heads and shells, are mostly discarded directly, occupying land and polluting the environment, while their natural chitin, crude protein, amino acids, and trace elements like calcium and phosphorus are not effectively utilized. Livestock manure from large-scale farming, if directly dumped or returned to fields without proper treatment, easily causes non-point source pollution of soil and water bodies; the insect eggs and pathogens in the manure also pose biosafety risks.

[0004] Existing straw-based or manure-based seedling substrate technologies often involve simple mixing of single raw materials, lacking refined and harmless pretreatment of the raw materials. The products are prone to carrying pathogens and insect eggs, posing a risk of seedling burn and root rot. Furthermore, they generally do not incorporate crayfish by-products for nutrient enhancement and functional improvement, resulting in defects such as short nutrient release cycles, poor granular structure, and weak water and fertilizer retention capacity. These technologies are insufficient to meet the requirements of standardized substrates and robust seedling cultivation for large-scale machine transplanting.

[0005] Therefore, there is an urgent need to develop a rice seedling substrate and its preparation method that can synergistically utilize three types of waste: rice straw, crayfish by-products, and livestock manure, reduce the amount of natural arable soil used, and has a balanced nutrient ratio, stable structure, antibacterial and root-promoting properties, and is safe and reliable. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a seedling substrate and its preparation method. The substrate uses agricultural and aquatic waste as the core raw material and, through scientific component ratio and preparation process, replaces the main material of traditional nutrient soil, possessing both excellent physical and chemical properties and stable seedling raising effect.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a seedling substrate comprising the following raw materials in parts by weight: 40-60 parts of decomposed rice straw, 10-15 parts of shrimp powder, 25-35 parts of fermented livestock manure, 15-25 parts of special nutrient soil, 1-3 parts of acid-base regulator, 0.5-1.5 parts of water-retaining and binding agent, and 0.2-0.8 parts of microbial compound inoculant.

[0008] Decomposed rice straw provides long-lasting organic matter and a loose framework. A dosage below 40 parts results in excessive substrate bulk density and reduced aeration, while a dosage above 60 parts weakens fertilizer retention. Shrimp meal provides natural crude protein, chitin, and trace elements. 10-15 parts are sufficient to inhibit bacterial growth, promote root development, and enhance nutrient supply. Too little is ineffective, while too much increases costs and may cause localized high salt levels. Fermented livestock manure provides fast-acting and slow-release nitrogen, phosphorus, and potassium. 25-35 parts ensure basic nutrient supply. Below 25 parts requires additional fertilization, while above 35 parts may introduce excessive salt and ammonia nitrogen. Specialized nutrient soil acts as a structural framework and nutrient buffer. 15-25 parts, combined with waste materials, are sufficient for seedling cultivation, significantly reducing the amount of traditional nutrient soil used. pH regulators and water-retaining binders regulate the substrate pH to a slightly acidic environment of 5.5-6.5 and maintain granular structure, respectively. Microbial compound inoculants activate nutrients and inhibit soil-borne diseases.

[0009] Furthermore, the decomposed rice straw is crushed to a particle size of 2-5 mm, and then composted using high-temperature aerobic methods. The organic matter content is ≥30%, and the carbon-nitrogen ratio is controlled at 25:1-30:1. After composting, there is no raw straw or moldy odor. The particle size of 2-5 mm balances structural support and specific surface area, making it the preferred size for straw in the substrate.

[0010] The shrimp powder is a byproduct of crayfish processing, including shrimp heads and shells. It is prepared by washing to remove salt and impurities, drying at a low temperature of 60-70℃, pulverizing, passing through an 80-100 mesh sieve, and sterilizing. This fineness ensures the smooth release of nutrients during the seedling cultivation cycle, and the natural chitin and amino acids effectively exert antibacterial and root-promoting effects. The shrimp powder has an organic matter content ≥30% and a crude protein content ≥35%.

[0011] The fermented livestock manure is one or more of cow manure, sheep manure, and pig manure. After solid-liquid separation, straw is added as an auxiliary material and the manure is fermented at high temperature and aerobicly for 20 to 30 days. After harmless treatment, the mortality rate of insect eggs is ≥99%, the inactivation rate of pathogens is ≥98%, there is no foul odor, the organic matter content is ≥30%, and the heavy metal content meets the national limit standard for agricultural planting substrates. After crushing, the manure is passed through a 10-mesh sieve.

[0012] The specialized nutrient soil is a mixture of topsoil, humus, and peat moss in a 3:2:1 mass ratio. It is then dried, crushed, sieved through a 10-20 mesh screen, and sterilized by sun exposure. The pH value is 6.0-7.0, and the organic matter content is ≥30%. This blend of three soil types balances nutrient availability, aggregate structure, and water and fertilizer retention capacity, showing significant improvement over traditional single-soil nutrient solutions.

[0013] The pH regulator is a mixture of quicklime powder and humic acid in a mass ratio of 1-2:2-3, used to precisely control the overall pH value of the substrate to the suitable slightly acidic range for rice seedlings. The water-retaining and binding agent is a mixture of bentonite and sodium carboxymethyl cellulose in a mass ratio of 2-3:1, which has the functions of water absorption and retention, slow release of nutrients, and physical binding, and can effectively prevent the substrate in the seedling tray from becoming loose and clumped together after repeated irrigation.

[0014] The microbial compound inoculant is prepared by compounding Bacillus subtilis, Bacillus licheniformis, phosphorus-solubilizing and potassium-solubilizing bacteria, and nitrogen-fixing bacteria in a ratio of 2:1:1:1 with an effective viable count of ≥2 billion CFU / g. This compound microbial community can activate poorly utilized nutrients in the substrate through phosphorus-solubilizing, potassium-solubilizing, and nitrogen-fixing effects. It can also inhibit common soil-borne diseases in the seedling stage, such as damping-off and seedling blight, by antagonizing their presence in the soil. Furthermore, it can produce plant growth hormones to promote root development.

[0015] This invention also provides a method for preparing the above-mentioned seedling substrate, comprising the following steps: S1. Raw Material Pretreatment: Rice straw is crushed to 2-5mm and then composted at high temperature and aerobic temperature for 25-35 days at 55-65℃. After composting, it is dried until the moisture content is 15%-20% to obtain composted rice straw. Crayfish by-products are collected, washed to remove impurities and salt, dried at 60-70℃, crushed through an 80-100 mesh sieve, and sterilized to obtain crayfish powder. After solid-liquid separation of livestock manure, crushed straw is added as an auxiliary material to adjust the carbon-nitrogen ratio. High-temperature aerobic fermentation is carried out for 20-30 days, followed by drying and crushing through a 10 mesh sieve to obtain fermented livestock manure. Special nutrient soil is compounded according to the aforementioned proportions, dried, crushed, sieved, and sterilized by sun exposure before use.

[0016] S2. Preliminary mixing: Add the decomposed rice straw, fermented livestock manure and special nutrient soil into a horizontal mixer according to the formula, and mix at low speed at room temperature for 15-20 minutes to fully mix the fibrous raw materials and powdery raw materials to obtain the basic mixed base material.

[0017] S3. Refined Formulation: Add the prescribed amounts of shrimp powder, pH adjuster, and water-retaining binder to the base mixture, and continue mixing for 20-25 minutes at a higher stirring speed. During mixing, adjust the substrate moisture content to 20%-25% using low-pressure spraying or ventilation, and monitor the pH value to ensure it remains stable at 5.5-6.5.

[0018] S4. Microbial agent activation and mixing: Add the microbial compound agent to warm water at about 30℃ at a ratio of 1:10, stir and activate for 5 to 10 minutes, then spray it evenly onto the surface of the mixed matrix and stir at low speed for 5 to 10 minutes to make the microbial agent evenly adhere to the matrix particles.

[0019] S5. Aging and Packaging: After mixing, transfer the substrate to a well-ventilated, cool place to age for 3-5 days, turning it over 1-2 times during this period to promote nutrient integration and microbial activation. After aging, once all indicators meet the standards, package and seal to obtain the finished seedling substrate.

[0020] The seedling substrate prepared according to the above formula and process has a bulk density of 0.35–0.55 g / cm³. 3 The total porosity is 60%–75%, the available nitrogen content is 180–250 mg / kg, the available phosphorus content is 120–180 mg / kg, and the available potassium content is 150–220 mg / kg. All indicators meet the relevant industry standards for rice seedling transplanting substrates.

[0021] It contains at least the following beneficial technical effects: (1) The waste has a high resource utilization rate and significant ecological benefits. Using rice straw, crayfish by-products and livestock manure as the three major wastes as core raw materials, the proportion of natural nutrient soil has been greatly reduced to 15% to 25%, realizing the coordinated disposal and high-value recycling of agricultural and aquatic wastes.

[0022] (2) The nutrient ratio is scientifically balanced and adapted to the needs of seedlings throughout the entire cycle. The decomposed straw provides long-lasting organic matter and a fluffy framework, the shrimp meal supplements crude protein, amino acids, chitin and trace elements, and the fermented manure provides nitrogen, phosphorus and potassium with both fast and slow effects. The nutrients of the three types of raw materials complement each other and are released in a staggered manner, so there is no need for additional large amounts of topdressing during the seedling raising period.

[0023] (3) Excellent synergistic physical and chemical properties of the matrix. The acid-base regulator precisely controls the weakly acidic environment, the water-retaining and binding agent stabilizes the granular structure, the matrix has moderate bulk density and reasonable porosity, and the water retention, fertilizer retention and air permeability are all well synergistically excellent.

[0024] (4) Thorough harmless treatment ensures seedling safety. All organic raw materials undergo high-temperature composting or fermentation sterilization pretreatment, which, combined with the antagonistic and antibacterial effects of functional microbial agents, can effectively reduce the incidence of soil-borne diseases and reduce pesticide use.

[0025] (5) The preparation process is simple and feasible for industrialization. The raw materials are widely available, the process route is clear, the equipment requirements are not high, and it is suitable for large-scale production as well as local preparation by small and medium-sized seedling raising entities. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0032] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0033] Example 1 The raw materials of the seedling substrate in this embodiment are as follows: 50 parts decomposed rice straw, 12 parts shrimp powder, 30 parts fermented livestock manure, 20 parts special nutrient soil, 2 parts acid-base regulator, 1.0 part water-retaining and binding agent, and 0.5 parts microbial compound agent.

[0034] S1. Raw material pretreatment Composted rice straw: Crush and sieve the rice straw collected from the field to a particle size of 2-5 mm. Compost in a pile at a high temperature of 55-65℃ for 30 days. The composted material is dark brown, soft, with an organic matter content of 32% and a carbon-to-nitrogen ratio of 28:1. Dry it until the moisture content is 18% before use.

[0035] Shrimp powder: Collect shrimp heads and shells from crayfish processing enterprises, remove impurities, wash with clean water until there is no salt or fishy smell, drain, and dry at 65℃ for 24 hours until the moisture content is below 10%. Grind through an 80-mesh sieve and sterilize with ultraviolet ozone for 30 minutes to obtain shrimp powder. Organic matter content is 33%, and crude protein content is 37%.

[0036] Fermented livestock manure: Mix cow manure and pig manure (1:1) with fresh manure, separate the solid and liquid phases, add 10% crushed straw to the solid phase, and pile it up for high-temperature aerobic fermentation for 25 days. The pile temperature is ≥55℃, the mortality rate of insect eggs is 99.2%, and the inactivation rate of pathogens is 98.5%. After drying and crushing, it passes through a 10-mesh sieve, with an organic matter content of 31% and heavy metals meeting the standards.

[0037] Special nutrient soil: Take topsoil, humus and peat soil from the field and mix them in a ratio of 3:2:1. Let it dry for 3 days, crush it through a 16-mesh sieve, and sterilize it by strong sunlight exposure for 2 days (cumulative sunshine ≥16h). pH 6.5, organic matter 32%.

[0038] S2, Preliminary mixing Add 50kg of decomposed straw, 30kg of fermented manure, and 20kg of special nutrient soil to a horizontal mixer and mix at low speed at room temperature for 18 minutes until the materials are uniform to obtain the basic mixed base material.

[0039] S3, Refined Mixing Add 12 kg of shrimp powder, 2 kg of pH adjuster (quicklime powder: humic acid = 1:2), and 1.0 kg of water-retaining and binding agent (bentonite: sodium carboxymethyl cellulose = 2.5:1) to the base material, and stir at high speed for 22 minutes. During stirring, monitor and adjust the moisture content to 23% and pH 6.2.

[0040] S4, Microbial agent activation and mixing Take 0.5 kg of microbial compound inoculant (the microbial compound inoculant is prepared by compounding Bacillus subtilis, Bacillus licheniformis, phosphorus-solubilizing and potassium-solubilizing bacteria and nitrogen-fixing bacteria in an effective live bacteria ratio of 2:1:1:1, with an effective live bacteria count of 2.2 billion CFU / g), add 30℃ warm water at a ratio of 1:10 and activate for 8 minutes, then spray evenly on the substrate surface and stir at low speed for 8 minutes.

[0041] S5, Aging and Packaging The substrate was aged in a well-ventilated, shady place for 4 days, and stirred once on the second day. The finished product bulk density was 0.45 g / cm³. 3Total porosity 68%, available nitrogen 215 mg / kg, available phosphorus 152 mg / kg, available potassium 186 mg / kg. Dispensed and sealed.

[0042] Application Trial Used for machine-transplanted rice seedling raising of "Xiangzaoxian 45", the results were observed 18 days after sowing: germination rate 96%, seedling establishment rate 93%, seedling height 15.8cm, root count 12.3 / plant, strong root cohesion, able to be lifted as a whole without falling apart, and a transplant recovery period of 3 days. Compared with traditional nutrient soil substrate, the seedling establishment rate was 85%, and the root count was 9.1 / plant.

[0043] Example 2 The raw materials of the seedling substrate in this embodiment are as follows: 40 parts decomposed rice straw, 10 parts shrimp powder, 25 parts fermented livestock manure, 15 parts special nutrient soil, 1 part acid-base regulator, 0.5 parts water-retaining and binding agent, and 0.2 parts microbial compound agent.

[0044] S1. Raw material pretreatment Composted rice straw: Rice straw collected from the field is crushed and sieved, with a particle size controlled at 2-5mm. The crushed straw is piled up for high-temperature aerobic composting, maintaining the pile temperature at 55-65℃ for 25 days. When composting is complete, the material is dark brown, soft in texture, and has no raw straw smell. Testing shows an organic matter content of 31% and a carbon-to-nitrogen ratio of 30:1, meeting the standard for complete composting. After composting, it is spread out to dry until the moisture content reaches 15%, then bagged for later use.

[0045] Shrimp powder: Byproducts such as shrimp heads and shells from crayfish processing enterprises are collected. After manually removing impurities such as plastic bags, the powder is repeatedly washed with clean water until it is free of salt, fishy smell, and oil. After draining, it is sent to a drying device and dried at a low temperature of 60℃ for 36 hours until the moisture content drops below 10%. The dried material is then ground in a pulverizer, passed through an 80-mesh sieve, and then sterilized with ultraviolet light for 40 minutes to obtain the finished shrimp powder. Testing shows that the shrimp powder contains 31% organic matter and 35% crude protein, and is free of mold and impurities.

[0046] Fermented Livestock Manure: Fresh cow manure is taken and first separated into solid and liquid components, with the liquid portion processed separately. 8% crushed straw is added to the solid manure as an auxiliary material to adjust the carbon-to-nitrogen ratio. After mixing, the mixture is piled up for high-temperature aerobic fermentation over a 20-day period. During fermentation, the pile temperature is maintained above 55℃. Testing showed a 99.1% mortality rate for insect eggs, a 98.2% inactivation rate for pathogens, no foul odor, an organic matter content of 31%, and heavy metal content meeting national standards for agricultural planting substrates. After fermentation, the manure is spread out to dry, crushed, and sieved through a 10-mesh sieve for later use.

[0047] Special nutrient soil: Mix topsoil, humus, and peat moss in a 3:2:1 ratio by weight, spread out and dry for 2 days, then crush and pass through a 10-mesh sieve. Finally, sterilize by exposing to strong sunlight in summer for 2 days (cumulative effective sunshine duration ≥16 hours). Testing shows the special nutrient soil has a pH of 6.0 and an organic matter content of 31%.

[0048] S2, Preliminary mixing According to the formula, 40 kg of decomposed rice straw, 25 kg of fermented livestock manure, and 15 kg of special nutrient soil are put into a horizontal mixing machine in sequence and stirred at low speed at room temperature for 15 minutes until the three raw materials show no obvious color difference and no lumps remain, thus obtaining the basic mixed base material.

[0049] S3, Refined Mixing Add 10 kg of shrimp powder, 1 kg of pH adjuster (in which quicklime powder and humic acid are mixed at a mass ratio of 1:2), and 0.5 kg of water-retaining and binding agent (in which bentonite and sodium carboxymethyl cellulose are mixed at a mass ratio of 2:1) to the basic mixed substrate. Increase the stirring speed and continue mixing for 20 minutes. During the mixing process, samples were taken for testing, and the moisture content was finely adjusted by low-pressure spraying. The final substrate moisture content was 20%, and the pH value was measured to be 5.5, which met the requirements.

[0050] S4, Microbial agent activation and mixing Take 0.2 kg of microbial compound inoculant (the microbial compound inoculant is prepared by compounding Bacillus subtilis, Bacillus licheniformis, phosphorus-solubilizing and potassium-solubilizing bacteria, and nitrogen-fixing bacteria in an effective viable count ratio of 2:1:1:1, with an effective viable count of 2.2 billion CFU / g), add it to warm water at approximately 30℃ at a mass ratio of 1:10, stir evenly, and let it stand for 5 minutes to activate. Spray the activated bacterial solution evenly onto the surface of the mixed matrix, and then stir at low speed for 5 minutes to ensure that the bacterial solution is evenly adhered to the surface of the matrix particles.

[0051] S5, Aging and Packaging Transfer the mixed substrate to a well-ventilated, cool place, pile it into a loose heap, and let it age for 3 days. Stir it once on the second day during this period to promote moisture balance and nutrient integration within the substrate. After aging, the substrate will be a uniform dark brown color with a faint soil humus odor and no other unpleasant smell. Finished product testing: Bulk density 0.38 g / cm³ 3 The total porosity is 72%, available nitrogen is 188 mg / kg, available phosphorus is 125 mg / kg, and available potassium is 158 mg / kg. All indicators meet the relevant industry standards for rice seedling raising substrates. The substrate is then packaged into sealed bags to obtain the finished seedling raising substrate.

[0052] Application Trial The seedling substrate obtained in this embodiment was used for machine-transplanted seedling raising of the rice variety "Xiangzaoxian 45". After filling the seedling trays with the substrate, conventional sowing was performed, and the greenhouse was managed uniformly. Seedling quality was assessed 18 days after sowing. Results showed: germination rate 94%, seedling establishment rate 91%, average seedling height 14.6 cm, average root count 10.8 per seedling, well-formed root system, and the seedling clumps could be lifted as a whole without crumbling. The recovery period after transplanting was approximately 4 days. The control group used traditional nutrient soil substrate, with a seedling establishment rate of 85% and a root count of 9.1 per seedling at the same time. The experiment demonstrates that, under the parameters specified in the claims, the substrate of this embodiment still meets all performance requirements, and its seedling raising effect is significantly better than that of traditional nutrient soil.

[0053] Example 3 The raw materials of the seedling substrate in this embodiment are as follows: 60 parts decomposed rice straw, 15 parts shrimp powder, 35 parts fermented livestock manure, 25 parts special nutrient soil, 3 parts acid-base regulator, 1.5 parts water-retaining and binding agent, and 0.8 parts microbial compound agent.

[0054] S1. Raw material pretreatment Composted rice straw: Rice straw collected from the field is crushed and sieved, with a particle size controlled at 2-5mm. The crushed straw is then piled up for high-temperature aerobic composting, maintaining the pile temperature at 55-65℃ for 35 days. Upon completion of composting, the material is fully dark brown, loose in texture, and free of any raw straw residue. Testing shows an organic matter content of 33% and a carbon-to-nitrogen ratio of 25:1, indicating thorough composting. After composting, the straw is spread out to dry until the moisture content reaches 20%, then bagged for later use.

[0055] Shrimp powder: Byproducts such as shrimp heads and shells from crayfish processing enterprises are collected. After manually removing impurities such as plastic bags, the powder is repeatedly washed with clean water until it is free of salt, fishy smell, and oil. After draining, it is sent to a drying device and dried at 70℃ for 20 hours until the moisture content drops to 8%. The dried material is then ground in a pulverizer, passed through a 100-mesh sieve, and then sterilized with a combination of ultraviolet light and ozone for 30 minutes to obtain the finished shrimp powder. Testing shows that the shrimp powder contains 34% organic matter and 38% crude protein, with uniform fineness, no mold, and no impurities.

[0056] Fermented Livestock Manure: Fresh manure is mixed with pig and sheep manure at a 1:1 mass ratio. Solid-liquid separation is performed first, with the liquid portion treated separately. 12% crushed straw is added to the solid manure as an auxiliary material to adjust the carbon-nitrogen ratio. After mixing thoroughly, the mixture is piled up for high-temperature aerobic fermentation over a 30-day period. During fermentation, the pile temperature is maintained above 55℃, reaching a maximum of 68℃. Testing showed a 99.5% mortality rate for insect eggs and a 98.8% inactivation rate for pathogens. There is no foul odor, the organic matter content is 33%, and the heavy metal content meets national standards for agricultural planting substrates. After fermentation, the manure is spread out to dry, crushed, and sieved through a 10-mesh sieve for later use.

[0057] Special nutrient soil: Mix topsoil, humus, and peat moss in a 3:2:1 ratio by weight, spread out and dry for 4 days, then crush and pass through a 20-mesh sieve. Finally, sterilize by exposing to strong sunlight in summer for 3 days (cumulative effective sunshine duration ≥ 24 hours). Testing shows the special nutrient soil has a pH of 7.0 and an organic matter content of 33%.

[0058] S2, Preliminary mixing According to the formula, 60 kg of decomposed rice straw, 35 kg of fermented livestock manure, and 25 kg of special nutrient soil were sequentially added to a horizontal mixer and stirred at low speed at room temperature for 20 minutes. Because the amount of straw and manure used in this embodiment is relatively large, the total volume of materials is significantly increased compared to embodiments 1 and 2. The stirring time was appropriately extended to ensure that the three raw materials were fully and evenly mixed until the material was visually uniform in color and free of lumps, thus obtaining the basic mixed base material.

[0059] S3, Refined Mixing Add 15 kg of shrimp powder, 3 kg of pH adjuster (in which quicklime powder and humic acid are mixed in a 2:3 mass ratio), and 1.5 kg of water-retaining and binding agent (in which bentonite and sodium carboxymethyl cellulose are mixed in a 3:1 mass ratio) to the basic mixed substrate. Increase the stirring speed and continue mixing for 25 minutes. Due to the increased amount of manure, a slight ammonia odor can be smelled at the beginning of the mixing process. The ammonia odor gradually dissipates through continuous stirring and ventilation. Samples were taken for testing during the mixing process, and the moisture content was finely adjusted by low-pressure spraying. The final substrate moisture content was 25%, and the pH value was measured to be 6.5, both of which meet the requirements.

[0060] S4, Microbial agent activation and mixing Take 0.8 kg of the microbial compound inoculant (the microbial compound inoculant is prepared by compounding Bacillus subtilis, Bacillus licheniformis, phosphorus-solubilizing and potassium-solubilizing bacteria, and nitrogen-fixing bacteria in an effective viable count ratio of 2:1:1:1, with an effective viable count of 2.2 billion CFU / g), add it to warm water at approximately 30℃ at a mass ratio of 1:10, stir evenly, and let it stand for 10 minutes to activate. Spray the activated inoculant solution evenly onto the surface of the mixed substrate, then stir at low speed for 10 minutes to ensure the inoculant adheres fully and evenly. Due to the large total amount of substrate, appropriately extend the stirring time to ensure uniform distribution of the inoculant.

[0061] S5, Aging and Packaging Transfer the mixed substrate to a well-ventilated, cool place, pile it into a loose heap, and let it age for 5 days. During this period, stir it twice, once on the 2nd and once on the 4th day, for a total of 2 stirrings, to fully promote the integration of nutrients and the proliferation and activation of beneficial bacteria within the substrate. Continuously observe the substrate during the aging process; no heating, mold growth, or off-odors should be observed. After aging, the substrate will be a uniform dark brown color with a distinct forest humus odor. Finished product testing: Bulk density 0.52 g / cm³ 3The total porosity is 63%, available nitrogen is 242 mg / kg, available phosphorus is 175 mg / kg, and available potassium is 215 mg / kg. All indicators meet the relevant industry standards for rice seedling raising substrates and the nutrient content is at a high level. After being packaged into sealed bags, the finished seedling raising substrate is obtained.

[0062] Application Trial The seedling substrate obtained in this embodiment was used for machine-transplanted seedling raising of the rice variety "Xiangzaoxian 45". After filling the seedling trays with the substrate, conventional sowing was performed, and the greenhouse was managed uniformly. Seedling quality was assessed 18 days after sowing. Results showed: germination rate 95%, seedling establishment rate 92%, average seedling height 16.2 cm, average root count 13.1 / seedling, dark green leaves, robust stems, and stronger root cohesion than in Example 1. The seedling clumps did not crumble when lifted as a whole, and the recovery period after transplanting was only 3 days. The control group used traditional nutrient soil substrate, with a seedling establishment rate of 85% and a root count of 9.1 / seedling at the same time.

[0063] Experimental Example 1 Comparison of Example 1 with existing commodity matrix detection Table 1

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A seedling raising substrate, characterized by, The components include the following parts by weight: 40-60 parts of decomposed rice straw, 10-15 parts of shrimp powder, 25-35 parts of fermented livestock manure, 15-25 parts of special nutrient soil, 1-3 parts of acid-base regulator, 0.5-1.5 parts of water-retaining and binding agent, and 0.2-0.8 parts of microbial compound agent.

2. The seedling substrate according to claim 1, characterized in that, The decomposed rice straw has a particle size of 2-5 mm, an organic matter content of ≥30%, and a carbon-nitrogen ratio of 25:1-30:

1.

3. The seedling substrate according to claim 1, characterized in that, The shrimp powder is made from crayfish by-products through cleaning, drying, crushing, and sterilization. It has a fineness of 80-100 mesh, an organic matter content of ≥30%, and a crude protein content of ≥35%.

4. The seedling substrate according to claim 1, characterized in that, The fermented livestock manure is one or more of cow manure, sheep manure, and pig manure.

5. The seedling substrate according to claim 1, characterized in that, The special nutrient soil is obtained by mixing topsoil, humus, and peat soil in a mass ratio of 3:2:

1.

6. The seedling substrate according to claim 1, characterized in that, The acid-base regulator is a mixture of quicklime powder and humic acid in a mass ratio of (1-2):(2-3).

7. The seedling substrate according to claim 1, characterized in that, The water-retaining and binding agent is a mixture of bentonite and sodium carboxymethyl cellulose in a mass ratio of 2 to 3:

1.

8. The seedling substrate according to claim 1, characterized in that, The microbial compound inoculant is composed of Bacillus subtilis, Bacillus licheniformis, phosphorus-solubilizing and potassium-solubilizing bacteria, and nitrogen-fixing bacteria in a ratio of 2:1:1:1 with an effective live bacteria count of ≥2 billion CFU / g.

9. The method for preparing the seedling substrate according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mix well-rotted rice straw, fermented livestock manure and special nutrient soil according to the specified ratio to obtain basic mixed substrate; S2. Add shrimp powder, pH adjuster and water-retaining binder to the basic mixed base material, stir and mix, and adjust the moisture content to 20% to 25% and the pH to 5.5 to 6.5 to obtain the mixed matrix; S4. After activating the microbial compound agent, spray it onto the surface of the mixed substrate and stir to ensure that the agent adheres evenly. S5. Let the substrate stand for 3-5 days, turning it over 1-2 times during this period, to obtain the seedling substrate.

10. The application of the seedling substrate according to any one of claims 1 to 8 in artificial seedling raising and mechanized transplanting seedling raising of rice.

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