Preparation method and application of wormcast granular bacterial fertilizer

Abstract

The invention discloses a preparation method and application of a wormcast granular bacterial fertilizer, and the wormcast granular bacterial fertilizer is prepared by adopting a base material ratio of wormcast to humus of 7: 3 through mechanical granulation, 80 DEG C constant temperature drying, particle cooling and functional bacterial agent spraying. The product has a remarkable application effect on various crops such as corn (grain corn, fresh corn and silage corn), hot peppers, tomatoes, traditional Chinese medicinal materials (radix glehniae, radix saposhnikoviae and radix achyranthis bidentatae) and the like, can give full play to the synergistic interaction effect of organic matrixes and functional microorganisms, and is stable in fertilizer efficiency, convenient to apply and suitable for industrial continuous production and large-area popularization and application.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting technology, and in particular to a method for preparing and applying earthworm castings granular microbial fertilizer. Background Technology

[0002] Earthworm castings are rich in nutrients, high in organic matter and humus, and have stable physicochemical properties, making them a high-quality organic substrate. Humus can improve soil, enhance water and fertilizer retention, and buffering capacity. Traditional bio-organic fertilizers often use a process of mixing microbial agents with raw materials, followed by granulation and drying. High temperatures can easily lead to the inactivation of a large number of live bacteria, making it difficult to consistently achieve the required number of effective live bacteria in the product. Furthermore, the granule strength, uniformity, and storage and transportation performance are often suboptimal. To address the problems of high-temperature damage to bacteria and the difficulty in simultaneously ensuring granulation and the preservation of live bacteria, this invention provides a process that first prepares organic granules, dries and cools them, and then sprays bacteria onto the surface. This process ensures granule formation and stability while maximizing the retention of microbial activity, thereby enhancing fertilizer functionality. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing earthworm castings granular microbial fertilizer and its application.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for preparing earthworm castings granular microbial fertilizer includes the following steps:

[0006] Step 1: Weigh out the pre-treated earthworm castings and humus produced by feeding earthworms with cow dung as raw materials, and put the two raw materials into the mixing equipment in sequence. Mix them thoroughly until the color is uniform and there are no obvious lumps, so as to obtain a uniform and stable organic base material.

[0007] Step 2: The mixed organic base material is conveyed to the granulation equipment and mechanically processed into uniformly sized granular materials;

[0008] Step 3: The obtained granular material is sent to the drying equipment for hot air drying to ensure that the granules reach the specified moisture content and maintain the strength and appearance regularity of the granules.

[0009] Step 4: After the dried granules have cooled to room temperature, they are sent to a spray coating device or a drum mixer to spray functional microbial agents evenly on the surface of the granules, so that the agents are fully adsorbed on the surface of the granules. After mixing evenly again, the finished earthworm casting granule microbial fertilizer is obtained.

[0010] Preferably, in step 1, the pretreated earthworm castings and humus are weighed out as raw materials in a weight ratio of 7:3.

[0011] Preferably, in step 1, the earthworm castings are earthworm castings produced by feeding earthworms with cow dung, with a moisture content of ≤50% and a particle size passing through a 20–40 mesh sieve.

[0012] Preferably, in step 1, the humic substance is one or more combinations of humic acid raw materials, humic organic fertilizer, or plant-derived decomposed humic substance.

[0013] Preferably, in step 1, the mixing equipment is a twin-shaft mixer, a horizontal mixer, or a zero-gravity mixer; the granulation equipment is a disc granulator, a drum granulator, or an extrusion granulator.

[0014] Preferably, in step 1, the microbial agent is a compound functional microbial agent, containing one or more of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, nitrogen-fixing bacteria, and Bacillus, as well as extracted earthworm protease, with an effective viable count ≥ 5 × 10^8 CFU / g.

[0015] Preferably, in step 3, hot air drying is performed at a constant temperature of 80°C until the moisture content of the particles is ≤12%.

[0016] A type of earthworm castings granular microbial fertilizer is prepared by the method described above.

[0017] Application of earthworm castings granular microbial fertilizer in grain corn planting, sweet corn planting, silage corn planting, greenhouse pepper planting, greenhouse tomato planting, North American ginseng planting, Saposhnikovia divaricata planting, and Achyranthes bidentata planting.

[0018] The present invention achieves the following technical effects compared to the prior art:

[0019] The earthworm castings granule microbial fertilizer of this invention has broad market prospects. Its application can effectively solve the problem of resource utilization of livestock and poultry manure waste, reduce environmental pollution, extend the earthworm farming industry chain, and inject new vitality into rural industrial revitalization.

[0020] This invention uses earthworm castings produced by feeding earthworms with cow dung as the main raw material, and scientifically combines humus and highly active compound microbial agents to prepare earthworm casting granular microbial fertilizer. The resulting fertilizer is not only rich and balanced in nutrients, providing a continuous and stable supply of nutrients for crop growth, but also effectively improves the soil micro-ecological environment and enhances the soil's water retention, fertilizer retention, and nutrient supply performance through the addition of microbial agents.

[0021] Earthworm castings themselves have a good granular structure, and when combined with humus, they further enhance soil aeration and water retention, promoting crop root growth and development. Simultaneously, the functional strains of phosphorus-solubilizing bacteria, potassium-solubilizing bacteria, and nitrogen-fixing bacteria in the compound microbial agent, as well as the extracted earthworm protease, can convert phosphorus, potassium, and other minerals in the soil that are difficult for crops to absorb and utilize into an absorbable form, and fix nitrogen from the air, significantly improving fertilizer utilization and reducing the application of chemical fertilizers.

[0022] Furthermore, the preparation method of this invention is rationally designed. Through specific mixing, granulation, and drying methods, it ensures excellent physical properties of the fertilizer, such as particle size and moisture content, facilitating storage, transportation, and application. Applying this earthworm casting granular microbial fertilizer to crops such as grain corn, sweet corn, silage corn, chili peppers, tomatoes, North American ginseng, Saposhnikovia divaricata, and Achyranthes bidentata can significantly promote crop growth, increase crop biomass and yield, and enhance the content of effective active ingredients in medicinal herbs. This demonstrates good economic and ecological benefits and provides strong technical support for sustainable agricultural development. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation method of earthworm castings granular microbial fertilizer according to the present invention.

[0024] Field application and effects

[0025] The following describes the field application of the earthworm castings granular microbial fertilizer developed in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the application embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 (Application in kernel corn, sweet corn and silage corn):

[0027] Step 1: Preparation of the experimental site and fertilizer

[0028] Select a plot of land that is flat, has convenient irrigation and drainage, and has uniform soil fertility as the experimental field. Plow it to a depth of 25-30 cm, harrow it to make it flat and fine, and then make ridges according to the specifications of the plot. Remove weeds and stubble from the field.

[0029] Fertilizers tested: conventional compound fertilizer and earthworm castings granular microbial fertilizer.

[0030] Step 2: Experimental Design and Field Setup

[0031] This experiment included three experimental groups: grain corn, sweet corn, and silage corn. Each group had two treatments, and each treatment was replicated three times. A randomized block design was used, with plot dimensions of 3 m × 5 m and a plot spacing of 0.5 m. A 1 m wide protective row was set around the perimeter of the experimental plot. The fertilization schemes for each treatment are as follows:

[0032] 1. Grain maize experimental group

[0033] Treatment 1 (CK1): Conventional fertilization, applying 40 kg / mu of conventional compound fertilizer, without adding earthworm casting granules microbial fertilizer.

[0034] Treatment 2 (T1): In addition to conventional fertilization, apply 10 kg / mu of earthworm castings microbial fertilizer.

[0035] 2. Fresh Corn Experimental Group

[0036] Treatment 1 (CK2): Conventional fertilization, applying 50 kg / mu of conventional compound fertilizer, without adding earthworm casting granules;

[0037] Treatment 2 (T2): Reduce the application of conventional compound fertilizer by 20% (application rate 40 kg / mu), and increase the application of earthworm casting granular microbial fertilizer by 10 kg / mu.

[0038] 3. Silage Corn Experimental Group

[0039] Treatment 1 (CK3): Conventional fertilization, applying 40 kg / mu of conventional compound fertilizer, without adding earthworm casting granules;

[0040] Treatment 2 (T3): In addition to conventional fertilization, apply 10 kg / mu of earthworm casting granular microbial fertilizer.

[0041] All fertilizers are applied to the soil with the seeder, and sowing is carried out in the spring. The management measures for watering, weeding, and pest and disease control in the fields of each treatment are consistent.

[0042] Step 3: Sample Collection and Property Determination

[0043] During the two critical growth stages of maize—seedling stage and jointing stage—five healthy and uniformly growing maize plants were randomly selected from each plot, and the following agronomic traits were measured:

[0044] 1. Plant height: The natural height from the ground surface to the top of the plant;

[0045] 2. Stem diameter: Measure the diameter of the second internode at the base of the plant;

[0046] 3. Leaf area: The total leaf area of ​​a single plant is calculated using the method of leaf length × leaf width × correction coefficient;

[0047] 4. Root length: The longest root length measured from the base to the tip;

[0048] 5. Root system development level: The evaluation is based on the total number of roots, fresh weight of roots, and root-to-shoot ratio.

[0049] Step 4: Yield measurement at harvest time

[0050] When each type of corn reaches maturity and harvest standards, the yield is calculated based on individual plots:

[0051] 1. Grain corn: Measure the number of ears, number of kernels per ear, and thousand-kernel weight in each plot to calculate the yield per acre;

[0052] 2. Fresh sweet corn: Measure the number of fresh ears and the weight of a single ear in each plot, and calculate the yield per mu (unit of land area) of fresh ears;

[0053] 3. Silage corn: Measure the fresh weight of plants in the plot and convert it into yield per acre.

[0054] The results showed that applying earthworm castings granular microbial fertilizer promoted the growth of maize at all growth stages. During the seedling stage, it increased plant height, stem diameter, leaf area, and root length in grain maize, and increased plant height in sweet maize. The growth-promoting effect was even more significant during the jointing stage. The plant height, stem diameter, leaf area, and root system indicators of sweet maize, grain maize, and silage maize were all superior to the control group, with the leaf area showing the most significant difference. Furthermore, the growth period of maize treated with earthworm castings granular microbial fertilizer was advanced by 7-10 days, and that of chili peppers by 10-15 days. Grain maize yield increased by 180-450 catties / mu, silage maize yield increased by 1800-2000 catties / mu, and sweet maize yield increased by 500-700 catties / mu.

[0055] Example 2 (Application in greenhouse chili peppers):

[0056] Step 1: Preparation of the experimental site and fertilizer

[0057] Select a well-lit greenhouse or polytunnel with good ventilation and irrigation facilities as the experimental site. Clean up the previous crop residues and weeds inside the greenhouse, deep plow the soil to a depth of 25-30 cm, and level and rake it finely. Fertilizers used for testing: conventional chemical fertilizers and earthworm castings granular microbial fertilizer.

[0058] Step 2: Experimental Design and Field Setup

[0059] The experiment employed a single-factor randomized block design, dividing each experimental greenhouse into two equal plots, designated as the control group (CK) and the experimental group (T). The fertilization regimens for each treatment are as follows:

[0060] 1. Control group (CK): Conventional fertilization methods were used, with conventional chemical fertilizers applied, and no earthworm castings granular microbial fertilizer was added;

[0061] 2. Experimental group (T): On the basis of conventional fertilization, 40 kg / mu of earthworm casting granular microbial fertilizer was added.

[0062] Conventional fertilizers were applied to the soil once before transplanting and mixed thoroughly, while earthworm casting granules were applied in furrows. Chili seedlings were transplanted at a uniform spacing. Except for the different fertilization methods, the field management measures, such as temperature and humidity management, integrated water and fertilizer irrigation, and pest and disease control, were completely consistent across all treatments.

[0063] Step 3: Measurement of plant growth indicators

[0064] After the chili pepper seedlings have established themselves, plant growth indicators are measured every 15 days. Ten healthy plants are randomly selected from each plot and tagged accordingly.

[0065] 1. Plant height: Measure the natural height from the base of the stem to the top of the plant using a measuring tape;

[0066] 2. Stem diameter: Measure the diameter 2 cm above the base of the stem using vernier calipers;

[0067] 3. Leaf area: Select functional leaves in the middle of the plant, measure the leaf length and width, calculate the single leaf area by leaf length × leaf width × correction coefficient, and sum them up to obtain the single plant leaf area;

[0068] 4. Chlorophyll content: The relative chlorophyll content (SPAD value) of functional leaves was determined using a SPAD-502 chlorophyll meter.

[0069] Step 4: Production Index Measurement and Calculation

[0070] Record the yield throughout the entire growth period, starting from the harvest of the first chili pepper.

[0071] 1. Record each time: Record the number of fruits (fruit count) in each plot at each harvest, and randomly select 20 fruits to weigh each fruit.

[0072] 2. Calculate the yield per mu: Based on the actual yield and area of ​​the plot, calculate the yield per mu for each treatment by converting it to standard mu (667 m²).

[0073] The results showed that the growth indicators of chili peppers treated with earthworm casting granules were higher than those treated with conventional fertilization. Plant height increased by 2.8%, stem diameter by 3.4%, leaf area by 4.3%, and fruit length by 4.1% compared to the control group. Overall, the application of earthworm casting granules was more beneficial to chili pepper growth. The yield increased by more than 2000 jin per mu, and the amount of residual peppers was significantly reduced.

[0074] Example 3 (Application on greenhouse tomatoes):

[0075] Step 1: Preparation of the experimental site and fertilizer

[0076] Select a well-lit greenhouse or polytunnel with good ventilation and irrigation facilities as the experimental site. Clean up the previous crop residues and weeds inside the greenhouse, deep plow the soil to a depth of 25-30 cm, and level and rake it finely. Fertilizers used for testing: conventional chemical fertilizers and earthworm castings granular microbial fertilizer.

[0077] Step 2: Experimental Design and Field Setup

[0078] The experiment employed a single-factor randomized block design, dividing the experimental shed into two equal plots, designated as the control group (CK) and the experimental group (T). The fertilization regimens for each treatment are as follows:

[0079] 1. Control group (CK): Conventional fertilization methods were used, with conventional chemical fertilizers applied, and no earthworm castings granular microbial fertilizer was added;

[0080] 2. Experimental group (T): On the basis of conventional fertilization, 40 kg / mu of earthworm casting granular microbial fertilizer was added.

[0081] Conventional fertilizers were applied to the soil once before transplanting and mixed thoroughly during land preparation. Earthworm casting granular microbial fertilizer was applied in furrows. Tomato seedlings were transplanted at a uniform plant and row spacing. Except for the different fertilization methods, the field management measures such as temperature and humidity management, integrated water and fertilizer irrigation, and pest and disease control were completely consistent across all treatments.

[0082] Step 3: Measurement of plant growth indicators

[0083] After the tomatoes have recovered from transplanting, the growth and development indicators of the tomatoes were measured every 15 days, and 5 healthy plants were randomly selected from each plot for labeling.

[0084] 1. Plant height: Measure the natural height from the base of the stem to the top of the plant using a measuring tape;

[0085] 2. Stem diameter: Measure the diameter 2 cm above the base of the stem using vernier calipers;

[0086] Tomato samples were collected and quality indicators were measured when the tomatoes were on the third cluster of fruit after they had matured and were ready for market.

[0087] Fruit diameter: Use a ruler / vernier caliper to measure the thickest part of the fruit;

[0088] Fruit longitudinal diameter: Use a vernier caliper or ruler to measure the length of the vertical straight line from the point where the fruit stalk attaches to the center of the fruit navel.

[0089] Single fruit weight: Select normal fruits of uniform maturity, remove the fruit stems, and weigh them using an electronic balance.

[0090] Step 4: Production Index Measurement and Calculation

[0091] Starting from the harvest of the first cluster of tomatoes, the yield throughout the entire growth period is recorded sequentially: after each harvest, the yield of tomatoes in each plot is recorded separately.

[0092] The results showed that the yield of the experimental group reached 17,903.2 catties / mu, while the yield of the locally conventionally fertilized group was 16,000 catties / mu, representing an increase of 11.90%. Compared with the locally conventionally fertilized group, the average single fruit weight, transverse diameter, and longitudinal diameter of the experimental group increased by 3.82%, 1.73%, and 8.61%, respectively.

[0093] Example 4 (Application in North American Ginseng):

[0094] Step 1: Experimental Site Preparation and Fertilizer Pretreatment

[0095] The experimental fields were selected as plots with flat terrain, convenient irrigation and drainage, and uniform soil fertility. The plots were deeply plowed to a depth of 25-30 cm, harrowed and leveled, and then made into ridges according to the specifications of the plots. The fertilizers used for the test were pre-treated as follows: nitrogen-phosphorus-potassium compound fertilizer (9-17-15), nitrogen-phosphorus-potassium compound fertilizer (14-16-12), bio-organic fertilizer, and earthworm castings granular microbial fertilizer.

[0096] Step 2: Setting up and seeding experimental plots

[0097] The field experiment on *Adenophora stricta* employed a quadratic D-saturation optimal design with N, P, and K as the three-factor fertilization. The experiment used a randomized block design with 10 different fertilization treatments, each replicated three times, for a total of 30 plots. The plots were spaced 2.5 m × 4 m, totaling 300 m². 2 Four types of fertilizers were selected: compound fertilizer (9-17-15), compound fertilizer (14-16-12), zero-degree bio-organic fertilizer, and earthworm casting granular microbial fertilizer. Four treatments were set up according to the recommended fertilization dosage, with each treatment replicated three times, for a total of 12 plots in a randomized block design.

[0098] In spring, North American ginseng is sown using a narrow-row sowing method, with a row spacing of 20 cm and a sowing depth of 4-5 cm. After sowing, the soil is covered and compacted. After emergence, seedlings are thinned to a spacing of 8-10 cm between plants. Field management measures, such as irrigation, weeding, and pest and disease control, are consistent.

[0099] Step 3: Sample Collection and Characteristic Investigation

[0100] Sampling began after seedling establishment and was conducted every 20 days. Three healthy, uniformly growing *Adenophora stricta* plants were randomly selected from each plot, and the following traits were measured:

[0101] 1. Agronomic traits: plant height (length of longest lateral branch), root length (measured in the middle and late stages to a root tip diameter of 3 mm), and rootstock diameter;

[0102] 2. Biomass indicators: plant fresh weight, plant dry weight, root fresh weight, and root dry weight;

[0103] 3. Physiological indicators: chlorophyll content.

[0104] After each sampling, the root samples were cleaned and used for the determination of coumarin content.

[0105] Step 4: Biomass and Coumarin Component Detection

[0106] 1. Biomass determination

[0107] Separate the above-ground parts and roots of fresh North American ginseng plants, rinse them thoroughly with clean water, drain them, and weigh them. Place them in a forced-air drying oven, blanch them at 105 ℃ for 15 min, and dry them at 65 ℃ until constant weight. Weigh them and record the data. Crush the dried roots, pass them through a 40-mesh sieve, and seal them for later use.

[0108] 2. Determination of coumarin content

[0109] Accurately weigh 2.0 g of North American ginseng root powder, place it in a 50 ml centrifuge tube, add 40 ml of methanol, vortex for 2 min; extract by ultrasonication for 1 h, cool to room temperature, add methanol to 50 ml, shake well; filter through a 0.20 μm microporous membrane, collect the filtrate for later use.

[0110] Detection was performed using UPLC (ultra-high performance liquid chromatography) under the following chromatographic conditions: Agilent SB-C 18 The chromatographic column was used with acetonitrile-water as the mobile phase, a flow rate of 1.0 ml / min, a detection wavelength of 250 nm, a column temperature of 30 ℃, and an injection volume of 20 μl. The contents of psoralen, imperatorin, and isoimperatorin were calculated based on the peak areas.

[0111] Step 5: Data Statistical Analysis

[0112] All experimental data were processed using statistical software. The mean ± standard deviation was calculated, and the significance of the differences was tested by analysis of variance (ANOVA). P < 0.05 was considered significant, and P < 0.01 was considered highly significant.

[0113] The results showed that, based on the two-year experimental screening and verification, the selected ratio of earthworm castings granular microbial fertilizer and N1P1K3 (17:21:9.2) for the aboveground plant and underground root growth traits and yield of *Adenophora stricta* were not significantly different from those of the traditional farming method, with a dry yield exceeding 600 kg / mu. The results were even better under conditions of combined organic fertilizer application and topdressing during key growth stages. Compared to traditional farming, this treatment achieved the same yield with a 43% reduction in chemical fertilizer application. Based on fertilizer market prices, this treatment reduced economic input by 120 yuan per mu compared to traditional farming, further demonstrating that this ratio can achieve better yields for *Adenophora stricta*, achieving cost reduction and efficiency improvement compared to the high fertilizer application rates previously used by farmers.

[0114] Example 5 (Application in wind protection):

[0115] Step 1: Experimental Site Preparation and Fertilizer Pretreatment

[0116] The experimental fields were selected from flat, well-drained, and uniformly fertile plots. The soil was deeply plowed to a depth of 25-30 cm, leveled, and finely harrowed before being made into raised beds according to plot specifications. The tested fertilizers were pretreated as follows: nitrogen fertilizer was urea, phosphorus fertilizer was superphosphate, potassium sulfate was potassium sulfate, and earthworm castings granular microbial fertilizer.

[0117] Step 2: Setting up and seeding experimental plots

[0118] The fertilization experiment employed a quadratic D-saturation optimal design based on N, P, and K factors, with 10 different fertilization treatments. Each treatment was randomly replicated three times. The plot size was 2.5 m × 4.5 m, with a plot spacing of 0.5 m, and a 1 m wide protective row was set around the experimental plot.

[0119] For spring sowing, use narrow-row sowing with a row spacing of 20cm, a plant spacing of 8-10cm after seedling establishment, and a sowing depth of 4-5cm. After sowing, cover with soil and compact. Apply earthworm castings granular microbial fertilizer as a base fertilizer at the recommended dosage (50-60 catties / mu) evenly. Apply nitrogen, phosphorus, and potassium fertilizers as base fertilizer evenly to each plot. Follow-up field management practices consistent with those of local farmers.

[0120] Step 3: Windproof sample collection and index determination

[0121] Sampling was conducted in July, August, September, and November to determine growth indicators of Saposhnikovia divaricata. Yield and effective component content were measured at harvest. Three plants were randomly selected from each plot, and their plant height, stem weight, root diameter, root weight, yield, and chromogen content were measured. The dry and fresh weights of both above-ground and underground parts were weighed using a balance. Saposhnikovia divaricata yield was calculated as the sum of the root weights of all plants in the plot. The remaining Saposhnikovia divaricata samples were placed in an oven and blanched at 105℃, then dried at a constant temperature of 60℃ to constant weight. The dried samples were then pulverized and passed through a 100-mesh sieve for storage.

[0122] Step 4: Determination of the content of chromone in the anti-wind-proof material

[0123] Accurately weigh 0.50 g of sample, add 15 mL of 70% ethanol, and extract using a microwave extraction instrument (Mars 6 xpress) at 90 °C for 3 min. Filter and collect the filtrate. The contents of four chromogens in the filtrate, including cimicifugoside, cimicifugoside, 5-O-methylvisamidolol, and hyoscyamine, were determined using an Agilent 1260 high-performance liquid chromatograph.

[0124] Chromatographic conditions were as follows: Diamonsil C18 column (4.6 mm × 200 mm, 5 μm), column temperature 30 ℃, injection volume 5 μL, detection wavelength 254 nm. Methanol-water gradient elution was used: 0–15 min, 20%–45% methanol; 15–25 min, 45–70% methanol, flow rate 1 mL / min. The content of saposhnikovia root extract was calculated based on the peak area.

[0125] Step 5: Data Statistical Analysis

[0126] All experimental data were processed using statistical software. The mean ± standard deviation was calculated, and the significance of the differences was tested by analysis of variance (ANOVA). P < 0.05 was considered significant, and P < 0.01 was considered highly significant.

[0127] The results showed that compared with the treatment without earthworm casting granules, the content of cimicifugain glycosides increased by 3.85%, the content of 5-O-methylvisamidol glycosides increased by 18.04%, and the content of purslanosides increased by 127.73%. The yield increased by 17.67%.

[0128] Example 6 (Application in Achyranthes bidentata):

[0129] Step 1: Experimental Site Preparation and Fertilizer Pretreatment

[0130] The experimental fields were selected from flat, well-drained, and uniformly fertile plots. The soil was deeply plowed to a depth of 25-30 cm, leveled, and finely harrowed before being made into raised beds according to plot specifications. The tested fertilizers were pretreated as follows: nitrogen fertilizer was urea, phosphorus fertilizer was superphosphate, potassium sulfate was potassium sulfate, and earthworm castings granular microbial fertilizer.

[0131] Step 2: Setting up and seeding experimental plots

[0132] The fertilization experiment employed a quadratic D-saturation optimal design based on N, P, and K factors, with 10 different fertilization treatments. Each treatment was randomly replicated three times. The plot size was 2.5 m × 4.5 m, with a plot spacing of 0.5 m, and a 1 m wide protective row was set around the experimental plot.

[0133] For spring sowing, use narrow-row sowing with a row spacing of 20cm, a plant spacing of 8-10cm after seedling establishment, and a sowing depth of 4-5cm. After sowing, cover with soil and compact. Apply earthworm castings granular microbial fertilizer as a base fertilizer at the recommended dosage (50-60 catties / mu) evenly. Apply nitrogen, phosphorus, and potassium fertilizers as base fertilizer evenly to each plot. Follow-up field management practices consistent with those of local farmers.

[0134] Step 3: Sample Collection and Characteristic Investigation

[0135] Samples were taken once each at the seedling stage, the seedling stage, and the elongation stage, and yield was measured at harvest. Three healthy, uniformly growing plants were randomly selected from each plot, and the following traits were measured:

[0136] 1. Agronomic traits: plant height (length of longest lateral branch), root length (measured in the middle and late stages to a root tip diameter of 3 mm), and rootstock diameter;

[0137] 2. Biomass indicators: plant fresh weight, plant dry weight, root fresh weight, and root dry weight;

[0138] 3. Physiological indicators: chlorophyll content.

[0139] Step 4: Detection of β-ecdysterone content

[0140] 1. Biomass determination

[0141] Separate the above-ground parts and roots of fresh Achyranthes bidentata plants, rinse them thoroughly with clean water, drain them, and weigh them. Place them in a forced-air drying oven, blanch them at 90 ℃ for 30 min, and dry them at 60 ℃ until constant weight. Weigh them and record the data. Crush the dried roots, pass them through a 40-mesh sieve, and seal them for later use.

[0142] 2. Determination of β-ecdysterone content

[0143] Accurately weigh approximately 1 g of the powder (passed through a No. 3 sieve), place it in a stoppered conical flask, add 30 ml of water-saturated n-butanol, seal tightly, soak overnight, sonicate (300 W, 40 kHz) for 30 minutes, filter, wash the container and residue several times with 10 ml of methanol, combine the filtrate and washings, evaporate to dryness, dissolve the residue in methanol, transfer to a 5 ml volumetric flask, add methanol to the mark, and shake well. For the assay, accurately pipette 10 μL each of the reference solution and the test solution, inject into the liquid chromatograph, and determine the result.

[0144] Step 5: Data Statistical Analysis

[0145] All experimental data were processed using statistical software. The mean ± standard deviation was calculated, and the significance of the differences was tested by analysis of variance (ANOVA). P < 0.05 was considered significant, and P < 0.01 was considered highly significant.

[0146] The results showed that appropriate application of earthworm castings granular microbial fertilizer combined with nitrogen, phosphorus, and potassium could increase the yield of Achyranthes bidentata, with a yield increase of 44.48% compared with the plots without earthworm castings granular microbial fertilizer. The content of the active ingredient β-ecdysterone increased by 18.18%-28.18%.

[0147] Conclusion: The application of earthworm castings granular microbial fertilizer significantly promoted the growth of grain corn, sweet corn, silage corn, peppers, tomatoes, and medicinal herbs such as *Adenophora stricta*, *Saposhnikovia divaricata*, and *Achyranthes bidentata*. Specifically, the growth period of corn was advanced by 7-10 days, while the growth period of greenhouse peppers and tomatoes was advanced by 10-15 days. In terms of yield, grain corn yield increased by 180-450 catties / mu, silage corn yield increased by 1800-2000 catties / mu, and sweet corn yield increased by 500-700 catties / mu; greenhouse pepper yield increased by over 2000 catties / mu, with a significant reduction in residual peppers; and greenhouse tomato yield increased by 11.90%.

[0148] In terms of traditional Chinese medicinal materials, the improvement in the content of effective components is particularly prominent: in *Adenophora stricta*, psoralen increased by 409.28%, imperatorin by 68.83%, and isoimperatorin by 1.92%; in *Saposhnikovia divaricata*, the content of cimicifuga glycoside increased by 3.85%, 5-O-methylvisamidol glycoside by 18.04%, and purslanoside by 127.73%, with a 17.67% increase in yield; and in *Achyranthes bidentata*, the content of β-ecdysterone increased by 18.18%-28.18%. Earthworm castings granular microbial fertilizer can effectively help farmers increase production and income, and its market prospects are broad. At the same time, the application of earthworm castings granular microbial fertilizer can also realize the resource utilization of livestock and poultry manure waste, reduce environmental pollution, extend the earthworm farming industrial chain, and inject new vitality into rural industrial revitalization.

[0149] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing earthworm castings granular microbial fertilizer, characterized in that, Includes the following steps: Step 1: Weigh out the pre-treated earthworm castings and humus produced by feeding earthworms with cow dung as raw materials, and put the two raw materials into the mixing equipment in sequence. Mix them thoroughly until the color is uniform and there are no obvious lumps, so as to obtain a uniform and stable organic base material. Step 2: The mixed organic base material is conveyed to the granulation equipment and mechanically processed into uniformly sized granular materials; Step 3: The obtained granular material is sent to the drying equipment for hot air drying to ensure that the granules reach the specified moisture content and maintain the strength and appearance regularity of the granules. Step 4: After the dried granules have cooled to room temperature, they are sent to a spray coating device or a drum mixer to spray functional microbial agents evenly on the surface of the granules, so that the agents are fully adsorbed on the surface of the granules. After mixing evenly again, the finished earthworm casting granule microbial fertilizer is obtained.

2. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 1, pretreated earthworm castings and humus are weighed out as raw materials in a weight ratio of 7:

3.

3. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 1, the earthworm castings are earthworm castings produced by feeding earthworms with cow dung, with a moisture content of ≤50% and a particle size that passes through a 20–40 mesh sieve.

4. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 1, the humic substance is one or more combinations of humic acid raw materials, humic organic fertilizer, or plant-derived decomposed humic substance.

5. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 1, the mixing equipment is a twin-shaft mixer, a horizontal mixer, or a zero-gravity mixer; the granulation equipment is a disc granulator, a drum granulator, or an extrusion granulator.

6. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 1, the microbial agent is a compound functional microbial agent, containing one or more of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, nitrogen-fixing bacteria, and Bacillus, as well as extracted earthworm protease, with an effective viable count ≥ 5 × 10^8 CFU / g.

7. The method for preparing earthworm castings granular microbial fertilizer according to claim 1, characterized in that, In step 3, hot air drying is carried out under a constant temperature of 80°C until the moisture content of the particles is ≤12%.

8. A type of earthworm castings granular microbial fertilizer, characterized in that, Prepared by the method described in claims 1–7.

9. The application of the earthworm castings granular microbial fertilizer according to claim 8 in the cultivation of grain corn, sweet corn, silage corn, greenhouse chili peppers, greenhouse tomatoes, North American ginseng, Saposhnikovia divaricata, and Achyranthes bidentata.

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