Compound microbial pesticide fertilizer capable of simultaneously preventing and treating root-knot nematode and soil-borne fungal diseases

Abstract

The invention relates to the crossing field of agricultural biological control and fertilizer technology, and discloses a compound microbial pesticide fertilizer capable of simultaneously controlling root-knot nematode and soil-borne fungal diseases, the pesticide fertilizer has a core-shell structure, and comprises an inner inorganic nutrition core, a middle isolation buffer layer and an outer functional bacterial layer; the raw materials comprise inorganic nutrition core particles, a biological activation organic carrier, composite functional bacterial powder and a modified slow-release binder. Wherein the binder is prepared from oxidized starch and PVA through borax crosslinking, so that the particle strength is enhanced; the carrier is fermented and activated, and synergistic components such as azadirachtin are added. An organic isolation buffer layer is constructed through a layered coating process, osmotic pressure stress of inorganic salt on microorganisms is effectively blocked, and the problem of strain inactivation is solved; the synergistic compounding of paecilomyces lilacinus, pochonia chlamydosporia, trichoderma harzianum and bacillus subtilis is utilized to realize the comprehensive prevention and control of root-knot nematode and soil-borne fungal diseases, and has the functions of nutrient slow release and crop resistance induction.

Description

Technical Field

[0001] This invention relates to the intersection of agricultural biological control and fertilizer technology, and in particular to a compound microbial fertilizer that can simultaneously control root-knot nematodes and soil-borne fungal diseases. Background Technology

[0002] In current agricultural production, root-knot nematodes and soil-borne fungi (such as Fusarium causing wilt and root rot, and Rhizoctonia causing damping-off and sheath blight) are the two core soil-borne diseases that restrict crop yield and quality. These two types of pathogens often occur in the soil in a combined manner: the wounds formed by root-knot nematodes infecting the root system easily become gateways for soil-borne fungi to invade, and the two work together to cause damage, accelerating root rot and crop death.

[0003] Existing control technologies for the aforementioned complex diseases have significant limitations. While chemical pesticides are fast-acting, long-term use can disrupt soil aggregate structure and microecological balance, leading to increased crop resistance and excessive pesticide residues, which does not meet the needs of green agriculture. In terms of biological control, most existing microbial preparations have limited functions. For example, Paecilomyces lilacinus preparations primarily target nematodes, and Trichoderma preparations mainly target fungi. To combat complex infections, growers often need to purchase multiple products for mixed application or apply them repeatedly. This not only increases labor and economic costs but also, due to a lack of scientific compounding techniques, can easily lead to antagonistic effects between different sources of microbial agents, resulting in unstable control efficacy.

[0004] To address the issues of single-drug control and repeated application, the industry has attempted to combine microbial agents with fertilizers to create "integrated pesticide-fertilizer" products. However, this process faces significant technical challenges: commonly used inorganic fertilizers (such as urea and potassium salts) have high basicity indices, which, upon absorbing moisture, generate extremely high osmotic pressure within the granular microenvironment. Without effective isolation and protection, the active functional bacteria directly contact the high concentration of inorganic salts, easily leading to dehydration and death due to osmotic pressure stress. Existing simple mixing or conventional coating processes struggle to establish an effective buffer system between inorganic nutrients and active bacteria, resulting in low survival rates and colonization difficulties for the functional bacteria during storage and initial soil application. Furthermore, some products exhibit a disconnect between disease treatment and nutrition, or between chemical fertilizer application and disease prevention, failing to provide the necessary nutritional support for crop root repair while controlling diseases. Therefore, developing a compound microbial pesticide-fertilizer that can effectively isolate inorganic salt stress, provide synergistic control of nematodes and fungal diseases, and possesses good colonization capabilities is a pressing issue for the industry. Summary of the Invention

[0005] The purpose of this invention is to provide a compound microbial fertilizer that can simultaneously prevent and control root-knot nematodes and soil-borne fungal diseases, aiming to solve the problems of low survival rate of functional bacteria, difficulty in bacterial colonization, and limited disease control spectrum caused by inorganic salts in existing fertilizers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a compound microbial fertilizer that simultaneously controls root-knot nematodes and soil-borne fungal diseases, comprising a core-shell structure with an inner inorganic nutrient core, a middle isolation buffer layer, and an outer functional bacterial layer; the compound microbial fertilizer is made from raw materials comprising the following parts by weight:

[0007] 400-500 servings of inorganic nutrient core granules;

[0008] 350-450 parts of bio-activated organic carrier;

[0009] 50-100 parts of compound functional microbial powder;

[0010] 20-40 parts of modified slow-release binder;

[0011] The isolation buffer layer is formed by bonding the bio-activated organic carrier with the modified slow-release binder and coating it onto the surface of the inorganic nutrient core particles; the functional bacterial layer is formed by bonding the composite functional bacterial powder with the modified slow-release binder and coating it onto the surface of the isolation buffer layer.

[0012] By adopting the above technical solution, the present invention utilizes the synergistic effect of multilayer structure and multiple components, including the following mechanism:

[0013] Physical Barrier and Salt Buffering Mechanism: This invention physically isolates the inner inorganic nutrient core from the outer functional bacterial layer through an isolation buffer layer. The urea and potassium salts in the inorganic nutrient core generate high osmotic pressure upon absorbing moisture; direct contact with these substances can lead to dehydration and inactivation of the microbial cells. The bio-activated organic carrier in the intermediate layer acts as a buffer medium, blocking the direct migration of inorganic salt ions to the surface bacterial agent and reducing the local basicity index, thereby significantly improving the survival rate of the functional bacteria during storage and the initial application period.

[0014] In-situ activation and colonization mechanism of microbial ecosystem: The bio-activated organic carrier, after fermentation, is rich in small-molecule organic carbon and nitrogen sources. When the fertilizer and pesticide are applied to the soil and come into contact with moisture, the outer layer of functional bacterial powder is the first to reactivate, and the adjacent organic carrier layer preferentially provides nutritional support for the reactivated bacterial strains. Compared to a barren soil environment, this structural feature allows functional bacteria to rapidly proliferate using the carrier's nutrients, inhibiting the growth of pathogens through niche competition and achieving rapid colonization of the dominant bacterial population.

[0015] Cross-linking network enhancement and slow-release mechanism: The modified slow-release binder constructs a cross-linking network structure between the layers. After drying, the binder forms a film with a certain degree of toughness, which on the one hand prevents the multi-layer structure from peeling off or pulverizing during transportation and mechanical fertilization; on the other hand, by adjusting the density of the film, it slows down the dissolution rate of inorganic nutrients in the inner layer, so that its release curve matches the nutrient requirements of crop growth, avoiding root damage or microbial inactivation caused by excessively rapid nutrient release.

[0016] Preferably, the composite functional bacterial powder comprises Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder, and Bacillus subtilis powder; the mass ratio of Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder to Bacillus subtilis powder is (1.0-1.5):(1.0-1.5):(1.5-2.0):(1.0-1.5).

[0017] By employing the above technical solutions, four strains were combined in different proportions to achieve integrated control of root-knot nematodes and soil-borne fungi:

[0018] (1) Paecilomyces lilacinus mainly parasitizes nematode eggs, while Puconia thunbergii mainly parasitizes nematode cysts and females. The two work together to block the reproductive cycle of nematodes.

[0019] (2) Trichoderma harzianum destroys the mycelial structure of soil-borne pathogenic fungi such as Fusarium through hyperparasitism and the secretion of lysozyme;

[0020] (3) Bacillus subtilis multiplies in the rhizosphere and secretes lipopeptides to inhibit other bacteria, while its metabolites can promote plant root growth. The four work together to achieve systematic control of underground diseases.

[0021] Preferably, the bio-activated organic carrier is made by microbial fermentation and activation of well-rotted organic fertilizer, mineral-derived potassium humate, and natural synergistic components; the natural synergistic components include azadirachtin extract, seaweed oligosaccharides, and chitosan.

[0022] By adopting the above technical solution, the pre-fermentation treatment of the carrier improves the bioavailability of organic matter. Among the natural synergistic components, azadirachtin has a feeding deterrent effect and can reduce nematode density; seaweed oligosaccharides and chitosan, as plant immune inducers, can induce crops to develop systemic acquired resistance, activate the plant's defense enzyme system, and further enhance the crop's disease resistance.

[0023] Preferably, the inorganic nutrient core particles are granulated from urea, monoammonium phosphate, potassium sulfate, and trace elements; the modified slow-release binder is prepared by cross-linking oxidized starch slurry and polyvinyl alcohol aqueous solution in the presence of borax and glycerol.

[0024] Preferably, in the raw materials for preparing the modified slow-release binder, the volume ratio of the oxidized starch slurry to the polyvinyl alcohol aqueous solution is 2:1; the oxidized starch slurry is obtained by oxidizing corn starch with hydrogen peroxide, and the mass concentration of the polyvinyl alcohol aqueous solution is 8%-10%.

[0025] By adopting the above technical solution, the borate ions provided by borax undergo a complexation and cross-linking reaction with the hydroxyl groups on the polyvinyl alcohol molecular chain and the active groups in the oxidized starch molecules, forming a three-dimensional network structure of starch-boron-polyvinyl alcohol. This modified binder has high bonding strength and water resistance, can effectively bond organic carriers with high filler content, and forms a hydrophobic film on the particle surface, reducing the impact of environmental humidity on the stability of the finished fertilizer product.

[0026] This invention also provides a method for preparing the compound microbial fertilizer, comprising the following steps:

[0027] S1. First layer of coating: Inorganic nutrient core particles are placed in a coating equipment, a portion of modified slow-release binder is sprayed on, then bio-activated organic carrier is sprinkled in, rolled and coated and hot air is blown through to form an isolation buffer layer.

[0028] S2, Second layer coating: The remaining modified slow-release binder is sprayed onto the surface of the particles obtained in step S1, followed by spraying composite functional bacterial powder, and flexibly rolling to coat and form a functional bacterial layer.

[0029] S3. Post-processing: The particles obtained in step S2 are sent to a low-temperature drying device for drying and then sieved to obtain the final product.

[0030] Preferably, the preparation steps of the modified slow-release binder include: oxidizing corn starch dispersion with hydrogen peroxide under alkaline conditions to obtain oxidized starch slurry; dissolving polyvinyl alcohol to obtain PVA aqueous solution; mixing oxidized starch slurry with PVA aqueous solution, adding borax and glycerol, stirring and reacting at a constant temperature of 60-70℃, and adjusting the pH to neutral after cooling to obtain the final product.

[0031] Preferably, the preparation steps of the bio-activated organic carrier include: mixing well-rotted organic fertilizer with mineral-derived potassium humate, adding an activator to adjust the moisture content, and fermenting at a constant temperature of 30-35°C for 24-36 hours; after fermentation, adding natural synergistic components and mixing evenly; the activator is a brown sugar solution or an aqueous solution of corn steep liquor powder.

[0032] Preferably, the preparation steps of the compound functional bacterial powder include: liquid fermentation of each single strain, adding a protective agent to the fermentation broth, and spray drying under an air inlet temperature of 130-140℃ to obtain powder of each single strain; mixing the powder of each single strain in proportion and adding diatomaceous earth dispersant; the protective agent includes trehalose and skim milk powder.

[0033] Preferably, in step S1, the amount of the modified slow-release adhesive sprayed accounts for 40%-50% of the total amount of adhesive, and the hot air purging temperature is 35-42℃; in step S3, the drying is low-temperature fluidized bed drying or low-temperature drying, the inlet air temperature is controlled at 35-40℃, and the drying time is 30-60 minutes.

[0034] By employing the above technical solution, this process ensures the complete construction of the core-shell structure through stepwise coating. Pre-granulation of the inorganic core at high temperature guarantees particle strength, while subsequent coating and drying processes are strictly controlled under low-temperature conditions, thereby preserving the bioactivity of functional bacteria, azadirachtin, and enzymes.

[0035] In summary, the present invention has at least one of the following beneficial technical effects:

[0036] 1. This invention constructs a structure consisting of an inner inorganic core, a middle organic buffer layer, and an outer functional bacterial layer. The organic buffer layer physically isolates high-basic-index inorganic nutrients from active bacterial strains. This structure effectively blocks the direct migration of inorganic salts to the surface, preventing microbial cell dehydration and inactivation due to localized high osmotic pressure, thus improving the survival rate of functional bacteria during storage and initial application. Simultaneously, the middle layer undergoes bio-activation treatment, providing readily available carbon and nitrogen sources for the outer bacterial strains to recover, promoting rapid proliferation and colonization of functional bacteria in the rhizosphere soil.

[0037] 2. This invention employs a compound of *Paecilomyces lilacinus*, *Puncodicarboxylum sclerotiorum*, *Trichoderma harzianum*, and *Bacillus subtilis*, utilizing the niche differences among these strains to achieve synergistic control. *Paecilomyces lilacinus* and *Puncodicarboxylum sclerotiorum* parasitize the eggs and cysts of root-knot nematodes, respectively, blocking nematode reproduction; *Trichoderma harzianum* inhibits the growth of pathogenic fungi such as *Fusarium* through hyperparasitism and the secretion of lysozyme; and *Bacillus subtilis* secretes lipopeptides and promotes root growth. The four strains complement each other through their niche differences, eliminating the risk of antagonism between strains and constructing a three-dimensional control system of ovicidal, parasitic, lysinic, and growth-promoting effects. This not only reduces the cost of mixed pesticide application for growers but also improves the control effect against the combined occurrence of root-knot nematodes and soil-borne diseases such as *Fusarium*.

[0038] 3. This invention utilizes a borax-crosslinked modified starch-polyvinyl alcohol binder to construct a dense, slow-release network between the granule layers. This improves the mechanical strength and water resistance of the fertilizer granules and slows down the dissolution rate of nutrients in the inner layers, preventing excessive nutrient release from damaging the root system. Furthermore, the natural active ingredients such as azadirachtin, seaweed oligosaccharides, and chitosan added to the bio-activated organic carrier can interfere with nematode feeding activities and induce systemic acquired resistance in crops. While providing nutrition, it activates the plant's own defense system, meeting the environmentally friendly requirements of green agriculture. Detailed Implementation

[0039] Preparation Examples 1-9:

[0040] Preparation Example 1:

[0041] This preparation example provides a homemade modified slow-release adhesive, including the following steps:

[0042] Starch oxidation treatment: Corn starch was dispersed in deionized water to prepare a 20% (w / w) starch slurry. Under stirring in a 35°C water bath, hydrogen peroxide solution (concentration 30%) equivalent to 1.0% of the starch mass was added. The pH was adjusted to 8.0 with 1 mol / L NaOH solution. The reaction was carried out for 40 minutes to obtain an oxidized starch slurry.

[0043] Polyvinyl alcohol (PVA) dissolution: Polyvinyl alcohol with a degree of polymerization of 1700 and a degree of alcoholysis of 87% is added to deionized water at 90°C and stirred to dissolve, thus preparing an 8% (w / w) PVA aqueous solution.

[0044] Cross-linking compounding: The prepared oxidized starch slurry and the prepared PVA aqueous solution are mixed at a volume ratio of 2:1.

[0045] Crosslinking reaction: Add 0.5% borax (as a crosslinking agent) and 1.5% glycerol (as a plasticizer) of the total mass of the mixture to the mixture, and stir at 60°C for 30 minutes.

[0046] Finished product: After cooling to room temperature, adjust the pH to 7.0 with 1 mol / L HCl solution to obtain the self-made modified slow-release adhesive.

[0047] Preparation Example 2:

[0048] This preparation example provides a homemade modified slow-release adhesive, including the following steps:

[0049] Starch oxidation treatment: Corn starch was dispersed in deionized water to prepare a 22% (w / w) starch slurry. Under stirring in a water bath at 38°C, hydrogen peroxide solution (concentration 30%) equivalent to 1.2% of the starch mass was added. The pH was adjusted to 8.5 with 1 mol / L NaOH solution. The reaction was carried out for 50 minutes to obtain an oxidized starch slurry.

[0050] Polyvinyl alcohol (PVA) dissolution: Polyvinyl alcohol with a degree of polymerization of 1750 and a degree of alcoholysis of 88% is added to deionized water at 92°C and stirred to dissolve to prepare a 9% (w / w) PVA aqueous solution.

[0051] Cross-linking compounding: The oxidized starch slurry obtained in step 2 is mixed with the PVA aqueous solution obtained in step 2 at a volume ratio of 2:1.

[0052] Crosslinking reaction: Add 0.8% borax and 1.8% glycerol by mass of the total mixture to the mixture, and stir at 65°C for 40 minutes.

[0053] Finished product: After cooling to room temperature and adjusting the pH to 7.0, the homemade modified slow-release binder is obtained.

[0054] Preparation Example 3:

[0055] This preparation example provides a homemade modified slow-release adhesive, including the following steps:

[0056] Starch oxidation treatment: Corn starch was dispersed in deionized water to prepare a 25% (w / w) starch slurry. Under stirring in a 40°C water bath, hydrogen peroxide solution (concentration 30%) equivalent to 1.5% of the starch mass was added. The pH was adjusted to 9.0 with 1 mol / L NaOH solution. The reaction was carried out for 60 minutes to obtain an oxidized starch slurry.

[0057] Polyvinyl alcohol (PVA) dissolution: Polyvinyl alcohol with a degree of polymerization of 1800 and a degree of alcoholysis of 89% is added to deionized water at 95°C and stirred to dissolve to prepare a 10% (w / w) PVA aqueous solution.

[0058] Cross-linking compounding: The oxidized starch slurry obtained in step 1 is mixed with the PVA aqueous solution obtained in step 2 at a volume ratio of 2:1.

[0059] Crosslinking reaction: Add 1.0% borax and 2.0% glycerol by mass of the mixture to the mixture, and stir at 70°C for 45 minutes.

[0060] Finished product: After cooling to room temperature and adjusting the pH to 7.0, the homemade modified slow-release binder is obtained.

[0061] Preparation Example 4:

[0062] This preparation example provides a compound functional bacterial powder, the preparation process of which is as follows:

[0063] The activation, liquid fermentation (29°C, 80 hours), addition of protective agent (4% addition amount) and spray drying (inlet air 135°C, outlet air 65°C) of each single strain were carried out according to the aforementioned general process.

[0064] Finally, the collected Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder, and Bacillus subtilis powder were mixed in a mass ratio of 1.2:1.2:1.8:1.2, and 8% of the total mass of diatomaceous earth dispersant was added. The mixture was then thoroughly mixed to obtain the final product.

[0065] Preparation Example 5:

[0066] This preparation example provides a compound functional bacterial powder, the preparation process of which is as follows:

[0067] The activation, liquid fermentation (28°C, 72 hours), addition of protective agent (3% addition amount) and spray drying (inlet air 130°C, outlet air 60°C) of each single strain were carried out according to the aforementioned general process.

[0068] Finally, the collected Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder, and Bacillus subtilis powder were mixed in a mass ratio of 1.5:1.5:1.5:1.0 (emphasizing the proportion of nematode parasitic fungi), and 5% of the total mass of diatomaceous earth dispersant was added and mixed evenly to obtain the final product.

[0069] Preparation Example 6:

[0070] This preparation example provides a compound functional bacterial powder, the preparation process of which is as follows:

[0071] The activation, liquid fermentation (30℃, 96 hours), addition of protective agent (5% addition amount) and spray drying (inlet air 140℃, outlet air 70℃) of each single strain were carried out according to the aforementioned general process.

[0072] Finally, the collected Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder, and Bacillus subtilis powder were mixed in a mass ratio of 1.0:1.0:2.0:1.5 (emphasizing the proportion of fungal antagonistic bacteria), and 10% of the total mass of diatomaceous earth dispersant was added and mixed evenly to obtain the final product.

[0073] Preparation Example 7:

[0074] This preparation example provides a bio-activated organic carrier, including the following steps:

[0075] Mixing: Add well-rotted organic fertilizer and mineral-derived potassium humate into the mixer at a mass ratio of 5:1.

[0076] Inoculation and adjustment: While stirring, spray a 40% brown sugar solution as an activator to adjust the moisture content of the mixture to 30%.

[0077] Isothermal enzymatic hydrolysis: The material is fed into an isothermal fermentation tank and sealed and piled up at 30°C for 36 hours.

[0078] Post-processing: After activation, add the formulated amount of natural synergistic components (azalea, seaweed oligosaccharide, chitosan), and stir at low speed (50 r / min) for 30 minutes to obtain the final product.

[0079] Preparation Example 8:

[0080] This preparation example provides a bio-activated organic carrier, including the following steps:

[0081] Mixing: Add well-rotted organic fertilizer and mineral-derived potassium humate into the mixer at a mass ratio of 6:1.

[0082] Inoculation and adjustment: While stirring, spray a 30% corn steep liquor dry powder aqueous solution as an activator to adjust the moisture content of the mixture to 35%.

[0083] Isothermal enzymatic hydrolysis: The material is fed into an isothermal fermentation tank and sealed and piled up at 35°C for 24 hours.

[0084] Post-processing: After activation, add the formulated amount of natural synergistic components (azalea, seaweed oligosaccharide, chitosan), and stir at low speed (60r / min) for 20 minutes to obtain the final product.

[0085] Preparation Example 9:

[0086] This preparation example provides an inorganic nutrient granule for use as the core of a fertilizer, and its preparation process is as follows:

[0087] Raw material ratio: Weigh 180kg of urea (containing 46% nitrogen), 120kg of monoammonium phosphate (containing 44% phosphorus), 150kg of potassium sulfate (containing 50% potassium), and 50kg of trace element additive package (EDTA chelated calcium, magnesium sulfate monohydrate, and zinc sulfate heptahydrate mixed in a 2:1:1 ratio).

[0088] Crushing and mixing: Feed the above raw materials into a crusher, crush them to a particle size ≤0.5mm, and mix them evenly.

[0089] Granulation: The mixed powder is fed into a rotary drum granulator, saturated steam is injected as a binding medium, and the material temperature is controlled at 65℃ to carry out agglomeration and granulation.

[0090] Drying and sieving: The granulated particles are sent to a rotary dryer and dried at 85℃ until the moisture content is ≤1.5%. After sieving, particles with a diameter between 2.0-4.0mm are selected as the inorganic nutrient core of the finished product.

[0091] Examples 1-4:

[0092] Example 1:

[0093] This embodiment provides a compound microbial fertilizer that simultaneously controls root-knot nematodes and soil-borne fungal diseases, specifically including the following steps:

[0094] Preparation of materials: Weigh 75 parts of the compound functional bacterial powder obtained in Preparation Example 4; weigh 400 parts of the bio-activated organic carrier obtained in Preparation Example 7 (which already contains natural synergistic components); weigh 450 parts of the inorganic nutrient core particles (particle size 2.5-3.5 mm) prepared in Preparation Example 9. Prepare 30 parts of the self-made modified slow-release binder obtained in Preparation Example 2.

[0095] First layer (isolation buffer layer):

[0096] The inorganic nutrient core particles were fed into the coating machine, and the rotation speed was adjusted to 18 r / min.

[0097] 14 parts of the self-made modified slow-release adhesive (approximately 47% of the total adhesive) were evenly sprayed through a high-pressure nozzle to fully wet the core surface;

[0098] Immediately and evenly sprinkle 400 parts of the bio-activated organic carrier, keep rolling for 8 minutes, so that the organic carrier is tightly adsorbed on the surface of the inorganic core;

[0099] Blow hot air at 38°C for 12 minutes to allow the isolation layer to initially solidify.

[0100] Second layer (functional bacterial layer):

[0101] After the first layer of coating is completed, spray the remaining 16 parts of the homemade modified slow-release binder onto the particle surface.

[0102] Immediately spray 75 parts of compound functional bacterial powder;

[0103] Adjust the rotation speed to 15 r / min and roll gently for 6 minutes to ensure that the bacterial powder adheres evenly to the outermost layer.

[0104] Post-processing:

[0105] The particles are fed into a low-temperature fluidized bed, the inlet air temperature is controlled at 38℃, and dried for 40 minutes.

[0106] Particles with a diameter of 3.0-4.5mm are sieved out, and the moisture content is tested to be 17.5%. The finished product is obtained by vacuum packaging.

[0107] Example 2:

[0108] This embodiment provides a compound microbial fertilizer that simultaneously controls root-knot nematodes and soil-borne fungal diseases, specifically including the following steps:

[0109] Preparation of materials: Weigh 50 parts of the compound functional bacterial powder (focusing on nematode resistance) prepared in Preparation Example 5; weigh 350 parts of the bio-activated organic carrier prepared in Preparation Example 8; weigh 400 parts of the inorganic nutrient core particles (particle size 2.0-3.0 mm) prepared in Preparation Example 9; and prepare 20 parts of the self-made modified slow-release binder (low viscosity type) prepared in Preparation Example 1.

[0110] First layer (isolation buffer layer):

[0111] Add the inorganic nutrient core particles into the coating machine and adjust the speed to 15 r / min;

[0112] Spray 8 parts of the self-made modified slow-release adhesive (accounting for 40% of the total amount);

[0113] Sprinkle in 350 portions of the bio-activated organic carrier and keep rolling for 6 minutes;

[0114] Blow in 35°C hot air for 10 minutes.

[0115] Second layer (functional bacterial layer):

[0116] Spray the remaining 12 parts of the homemade modified slow-release adhesive;

[0117] Spray 50 parts of compound functional bacterial powder;

[0118] Adjust the rotation speed to 12 r / min and roll gently for 5 minutes.

[0119] Post-processing:

[0120] The granules are fed into a low-temperature dryer, with the inlet air temperature controlled at 35°C, and dried for 30 minutes.

[0121] Particles with a diameter of 2.5-4.0 mm were sieved out, and the moisture content was found to be 18.2%. The finished product was then obtained by vacuum packaging.

[0122] Example 3:

[0123] This embodiment provides a compound microbial fertilizer that simultaneously controls root-knot nematodes and soil-borne fungal diseases, specifically including the following steps:

[0124] Preparation of materials: Weigh 100 parts of the compound functional bacterial powder (focusing on antifungal) prepared in Preparation Example 6; weigh 450 parts of the bio-activated organic carrier prepared in Preparation Example 7; weigh 500 parts of the inorganic nutrient core particles (particle size 3.0-4.0 mm) prepared in Preparation Example 9; and prepare 40 parts of the self-made modified slow-release binder (high viscosity type) prepared in Preparation Example 3.

[0125] First layer (isolation buffer layer):

[0126] The inorganic nutrient core particles were fed into the coating machine, and the rotation speed was adjusted to 22 r / min.

[0127] Spray 20 parts of the self-made modified slow-release adhesive (accounting for 50% of the total amount);

[0128] Sprinkle in 450 portions of bio-activated organic carrier and keep rolling for 10 minutes to ensure the formation of a thick isolation layer;

[0129] Blow in 40°C hot air for 15 minutes.

[0130] Second layer (functional bacterial layer):

[0131] Spray the remaining 20 parts of the homemade modified slow-release adhesive;

[0132] Spray 100 parts of compound functional bacterial powder;

[0133] Adjust the rotation speed to 18 r / min and roll gently for 8 minutes.

[0134] Post-processing:

[0135] The particles are fed into a low-temperature fluidized bed, the inlet air temperature is controlled at 40℃, and dried for 45 minutes.

[0136] Particles with a diameter of 3.5-5.0 mm were sieved out, and the moisture content was found to be 16.8%. The finished product was then obtained by vacuum packaging.

[0137] Example 4:

[0138] This embodiment provides a compound microbial fertilizer with the same raw material ratio as in Example 1, but the preparation process has been adjusted, including the following steps:

[0139] Preparation of materials: The types and amounts of raw materials are exactly the same as in Example 1 (i.e., the inorganic nutrient core particles prepared using Preparation Example 9).

[0140] First layer coating (rapid prototyping):

[0141] Increase the rotation speed to 25 r / min, spray the adhesive and then sprinkle it into the carrier, shortening the rolling time to 5 minutes;

[0142] Increase the hot air temperature to 42℃ (short-term high temperature) and blow for 8 minutes.

[0143] Second layer of coating:

[0144] The rotation speed is set to 20 r / min, and the rolling time is 5 minutes.

[0145] Post-processing:

[0146] Drying was performed at a low temperature of 36℃ for 60 minutes.

[0147] The screening and packaging process is the same as before.

[0148] Comparative Examples 1-6:

[0149] Comparative Example 1: The only difference from Example 1 is the preparation process: This comparative example does not use a layered coating process. Specifically, the inorganic nutrient core raw materials (i.e., a pulverized mixture of urea, monoammonium phosphate, potassium sulfate, and trace element packets, without pre-granulation), weighed according to the proportions of Preparation Example 9, the bio-activated organic carrier obtained in Preparation Example 7, the composite functional bacterial powder obtained in Preparation Example 4, and the dry powdered modified binder raw materials are directly added to a mixer and mixed evenly. Then, the mixture is fed into a rotary drum granulator, sprayed with water for granulation, and finally dried at the same low temperature.

[0150] Comparative Example 2: Compared with Example 1, the only difference is in the raw material treatment: the organic carrier used in this comparative example did not undergo the bio-targeted activation treatment as in Preparation Example 7. Specifically, the well-rotted organic fertilizer, mineral-derived potassium humate, and natural synergistic components in the raw materials of Preparation Example 7 were directly and physically mixed, and then used as a carrier for the subsequent coating step.

[0151] Comparative Example 3: Compared with Example 1, the only difference is the composition of the bacterial powder: This comparative example was adjusted in the preparation of the compound functional bacterial powder according to Preparation Example 4 so that it does not contain Trichoderma harzianum and Bacillus subtilis (i.e., it only contains the anti-nematode component), and the missing weight parts were made up by sterilized diatomaceous earth. The other steps and amounts were the same.

[0152] Comparative Example 4: Compared with Example 1, the only difference is the composition of the bacterial powder: This comparative example was adjusted in the preparation of the compound functional bacterial powder according to Preparation Example 4 so that it does not contain Paecilomyces lilacinus and Procambarus thallus (i.e., it only contains antifungal components). The missing weight parts were made up by sterilized diatomaceous earth. The other steps and amounts were the same.

[0153] Comparative Example 5: Compared with Example 1, the only difference is the choice of binder: In this comparative example, a common 5% corn oxidized starch aqueous solution is used instead of the self-made modified slow-release binder prepared in Preparation Example 2, and the other steps and amounts are the same.

[0154] Comparative Example 6: Compared with Example 1, the only difference is in the preparation of the bacterial powder: when preparing the compound functional bacterial powder according to Preparation Example 4, trehalose and skim milk powder were not added to the fermentation broth, and it was directly spray-dried. The remaining steps and amounts were the same.

[0155] Test Example 1-2:

[0156] Test Example 1:

[0157] Experimental subjects: The compound microbial fertilizer products prepared in Examples 1-3, as well as the samples prepared in Comparative Examples 1, 2, 5 and 6, were selected as test materials.

[0158] Experimental methods:

[0159] Effective viable bacteria retention rate determination: The above samples were separately packaged into polyethylene bags, vacuum-sealed, and placed in a constant temperature incubator (25±2℃) to simulate natural shelf life.

[0160] Samples were taken and tested at month 0 (initial value), month 3, and month 6 respectively;

[0161] The detection method was performed according to GB20287-2006 "Agricultural Microbial Inoculants". 10.0 g of sample was weighed and added to sterile water containing glass beads, then shaken and dispersed for 30 minutes to prepare a suspension. The serial dilution plate count method was used to determine the number of fungi and bacteria on potato dextrose agar (PDA) and nutrient agar (NA) media, respectively. The total viable count (CFU / g) was calculated using the formula: Retention rate (%) = (Viable count at time T / Viable count at month 0) × 100%.

[0162] Slow-release salt barrier performance test (conductivity method): This test aims to characterize the ability of the membrane structure to block the dissolution of internal inorganic salts, and indirectly reflect the potential threat of "salt leakage" to the external bacterial layer;

[0163] Weigh 5.0g of each sample and place it in a 250mL beaker. Add 200mL of deionized water.

[0164] Under constant temperature and static conditions of 25℃, the conductivity of the solution (EC value, unit: mS / cm) was measured using a DDS-307A conductivity meter after soaking for 1 hour and 24 hours, respectively.

[0165] The lower the EC value, the better the density of the outer coating layer, the slower the release of internal fertilizer salts, and the less salt stress on external microorganisms.

[0166] Experimental results: The viable bacterial retention rate and conductivity test data of each group of samples are shown in Table 1.

[0167] Table 1. Shelf life survival rate and conductivity changes of each group of samples

[0168] Group <![CDATA[Initial viable cell count (10 8 CFU / g)]]> 3-month retention rate (%) 6-month retention rate (%) Conductivity over 1 hour (mS / cm) 24-hour conductivity (mS / cm) Example 1 5.42 94.6 87.3 1.82 6.45 Example 2 4.89 92.1 85.4 2.05 7.12 Example 3 5.67 93.8 88.1 1.65 5.98 Comparative Example 1 5.35 42.5 14.2 16.84 28.70 Comparative Example 2 5.18 83.4 68.7 1.88 6.54 Comparative Example 5 5.26 76.2 55.9 6.32 18.41 Comparative Example 6 2.14 58.3 23.6 1.85 6.48

[0169] Results Analysis and Conclusions:

[0170] The necessity of a multi-layered physical isolation structure: The data from Example 1 and Comparative Example 1 differ significantly. Comparative Example 1 used mixed granulation, with inorganic salts directly contacting the bacterial cells, resulting in a 1-hour conductivity as high as 16.84 mS / cm, indicating rapid salt dissolution. This high osmotic pressure environment led to a bacterial survival rate of only 14.2% after 6 months. In contrast, Example 1 had a 1-hour conductivity of only 1.82 mS / cm, and a 6-month survival rate maintained at 87.3%. This demonstrates that the inorganic core-organic layer-bacterial layer structure effectively delayed the release of inorganic nutrients, reduced the osmotic pressure of the microenvironment, and solved the problem of high-concentration fertilizers killing the microorganisms.

[0171] Barrier effect of modified binder: Compared with Comparative Example 5, the product using ordinary oxidized starch binder (Comparative Example 5) had a higher 24-hour conductivity (18.41 mS / cm) than that of Example 1 using the self-made modified binder (6.45 mS / cm). The bacterial survival rate of Comparative Example 5 decreased to 55.9% after 6 months. This indicates that the PVA-containing binder prepared in this invention has higher film density and stronger hydrophobicity, which can prevent environmental moisture from rapidly penetrating into the fertilizer core, thereby protecting the survival environment of the external bacterial layer.

[0172] The role of carrier activation and stress protection: In Comparative Example 2, the carrier was not biologically activated, and its survival rate at month 6 was 68.7%, lower than that in Example 1. This indicates that the organic carrier activated by brown sugar composting provides a more favorable colonization substrate for exogenous functional bacteria by pre-proliferating indigenous bacteria and providing an easily available carbon source;

[0173] Comparative Example 6 lacked trehalose protectant, resulting in not only a low initial viable count (significant drying loss) but also rapid shelf-life degradation, demonstrating that stress protectant is crucial for maintaining the dormant stability of bacteria on the surface of dried particles.

[0174] In summary, this invention achieves stable coexistence between fertilizer and microorganisms through a dense barrier layer constructed with modified binders and a suitable microenvironment provided by a bio-activated carrier, ensuring a high number of effective viable bacteria in the product over a long shelf life.

[0175] Test Example 2:

[0176] Experimental subjects: Samples prepared in Examples 1, 2, and 3, as well as samples prepared in Comparative Example 3 (without antifungal strain) and Comparative Example 4 (without nematode-resistant strain).

[0177] Control group setup: Blank control (CK): Only an equal amount of ordinary compound fertilizer (NPK content consistent with Example 1) was applied, without any biocontrol bacteria.

[0178] Chemical control: Apply ordinary compound fertilizer and drench the roots with 1.8% abamectin EC (3000 times dilution) and 30% hymexazol Aqueous Solution (1500 times dilution).

[0179] Experimental methods:

[0180] Soil and pathogen inoculation: The experimental soil was collected from a continuous cropping greenhouse in Shouguang, Shandong Province. Tests showed that the plot was severely affected by root-knot nematodes and wilt disease. The collected soil was sieved and air-dried.

[0181] Artificial inoculation: Approximately 2000 second-instar larvae of the southern root-knot nematode and a suspension of Fusarium oxysporum cucumber-specific spores (containing approximately 1×10⁵ spores / g soil) were inoculated per kilogram of soil. After thorough mixing, the mixture was placed into 25cm diameter plastic pots, with each pot containing 5kg of soil.

[0182] Application of pesticides and planting: The test crop was cucumber (variety: Zhongnong 16).

[0183] Transplant seedlings when they reach the two-leaf-one-heart stage. Before transplanting, calculate the recommended field application rate of 50 kg per mu and evenly mix the fertilizer granules of each group into the potting soil (the chemical agent control group was treated with root irrigation on the day of transplanting).

[0184] Each treatment was replicated in 15 pots, with one plant per pot, and the plants were randomly arranged in a greenhouse and managed with standard water and fertilizer.

[0185] Survey indicators and methods: Disease incidence and growth indicators were investigated 45 days after transplanting.

[0186] Root-knot nematode disease index: Dig up the plant roots, wash them, and investigate the root knot condition according to the grading standard (0-4 levels). Calculate the root knot index and relative control efficacy.

[0187] Fusarium wilt incidence rate: Investigate browning at the base of the stem and wilting of the plant, and count the incidence rate and relative control efficacy of Fusarium wilt.

[0188] Plant height and fresh weight: Measure the height of the above-ground part of the plant and the fresh weight of the whole plant.

[0189] Experimental results: The control effects of each treatment group on cucumber root-knot nematodes and wilt disease, as well as the data on growth effects, are shown in Table 2.

[0190] Table 2. Statistical Table of Disease Index and Growth Indicators in Cucumber Pot Experiment

[0191] Processing Group Root knot index Relative efficacy against nematodes (%) Fusarium wilt disease incidence rate (%) Relative efficacy against Fusarium wilt (%) Plant height (cm) Fresh weight of the whole plant (g) Blank control (CK) 68.4 — 46.7 — 52.3 41.5 Chemical reagent comparison 18.2 73.4 12.6 73.0 78.6 65.2 Example 1 10.5 84.6 5.8 87.6 94.2 82.1 Example 2 12.8 81.3 7.2 84.6 89.5 77.4 Example 3 11.1 83.8 6.4 86.3 92.8 80.6 Comparative Example 3 (lacking antifungal properties) 13.2 80.7 34.2 26.8 68.4 55.3 Comparative Example 4 (lacking nematode resistance) 52.6 23.1 24.5 47.5 61.2 50.8

[0192] Note: “—” in the table indicates that it is not applicable.

[0193] Results Analysis and Conclusions:

[0194] Necessity and synergistic mechanism of strain combination: Example 1 showed the best comprehensive control effect, with nematode control effect of 84.6% and wilt disease control effect of 87.6%.

[0195] Comparative analysis showed that although Comparative Example 3 retained nematode-resistant strains (such as Paecilomyces lilacinus), its nematode control efficacy (80.7%) was similar to that of Example 1, but the wilt disease incidence rate was as high as 34.2%, indicating extremely low control efficacy. This suggests that microorganisms targeting nematodes alone cannot effectively control fungal diseases.

[0196] The key difference lies in Comparative Example 4 (lacking nematode-resistant strains), whose nematode control efficacy was only 23.1% (mainly due to substrate improvement). However, it's noteworthy that its wilt disease incidence reached 24.5%, higher than the 5.8% in Example 1. This confirms that root-knot nematode infection causes root wounds, providing a pathway for Fusarium oxysporum invasion (a combined infection effect). Example 1, by simultaneously killing nematodes and inhibiting fungi, interrupted the pathway of nematode-induced root damage leading to secondary fungal infection, achieving a synergistic control effect.

[0197] Biostimulation and growth-promoting effects: The cucumber plant height and fresh weight in the example group were significantly higher than those in the chemical agent control group. Although chemical agents can control diseases, they have no obvious direct promoting effect on plant growth.

[0198] The embodiments of the present invention utilize secondary metabolites such as auxin and gibberellin secreted by Trichoderma harzianum and Bacillus subtilis, as well as humic acid substances provided by bioactivated organic carriers, to directly promote root development and plant growth while controlling diseases, demonstrating the technical advantage of dual effects of pesticides and fertilizers.

[0199] In summary, this technical solution, through the scientific formulation of microbial communities with different functions and the combination of humic acid substances provided by bio-activated organic carriers, can effectively block the nematode-fungus complex disease cycle in complex soil micro-ecological environment. Its comprehensive application effect is better than that of single microbial agents or conventional chemical control methods.

Claims

1. A compound microbial fertilizer that simultaneously controls root-knot nematodes and soil-borne fungal diseases, characterized in that, The compound microbial fertilizer has a core-shell structure, including an inner inorganic nutrient core, a middle isolation buffer layer, and an outer functional bacterial layer. The compound microbial fertilizer is made from raw materials comprising the following parts by weight: Inorganic nutrient core granules: 400-500 servings; Bio-activated organic carrier: 350-450 parts; Compound functional microbial powder: 50-100 parts; Modified slow-release binder: 20-40 parts; The isolation buffer layer is formed by bonding the bio-activated organic carrier with the modified slow-release binder and coating it onto the surface of the inorganic nutrient core particles; the functional bacterial layer is formed by bonding the composite functional bacterial powder with the modified slow-release binder and coating it onto the surface of the isolation buffer layer.

2. The compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 1, characterized in that, The composite functional microbial powder includes Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder, and Bacillus subtilis powder. The mass ratio of Paecilomyces lilacinus powder, Puconia thunbergii powder, Trichoderma harzianum powder and Bacillus subtilis powder is (1.0-1.5):(1.0-1.5):(1.5-2.0):(1.0-1.5).

3. The compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 1, characterized in that, The bio-activated organic carrier is made by microbial fermentation and activation of well-rotted organic fertilizer, mineral-derived potassium humate, and natural synergistic components; the natural synergistic components include azadirachtin extract, seaweed oligosaccharides, and chitosan.

4. The compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 1, characterized in that, The inorganic nutrient core particles are made by granulation of urea, monoammonium phosphate, potassium sulfate, and trace elements. The modified slow-release binder is prepared by cross-linking oxidized starch slurry and polyvinyl alcohol aqueous solution in the presence of borax and glycerol.

5. A compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 4, characterized in that, In the raw materials for preparing the modified slow-release binder, the volume ratio of the oxidized starch slurry to the polyvinyl alcohol aqueous solution is 2:1; The oxidized starch slurry is obtained by oxidizing corn starch with hydrogen peroxide, and the mass concentration of the polyvinyl alcohol aqueous solution is 8%-10%.

6. The compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 1, characterized in that, The preparation method of the compound microbial fertilizer includes the following steps: S1. First layer of coating: Inorganic nutrient core particles are placed in a coating equipment, a portion of modified slow-release binder is sprayed on, then bio-activated organic carrier is sprinkled in, rolled and coated and hot air is blown through to form an isolation buffer layer. S2, Second layer coating: The remaining modified slow-release binder is sprayed onto the surface of the particles obtained in step S1, followed by spraying composite functional bacterial powder, and flexibly rolling to coat and form a functional bacterial layer. S3. Post-processing: The particles obtained in step S2 are sent to a low-temperature drying device for drying and then sieved to obtain the final product.

7. A compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 6, characterized in that, The preparation steps of the modified sustained-release adhesive include: The corn starch dispersion was oxidized by hydrogen peroxide under alkaline conditions to obtain an oxidized starch slurry. A PVA aqueous solution was prepared by dissolving polyvinyl alcohol. Mix oxidized starch slurry with PVA aqueous solution, add borax and glycerin, stir and react at a constant temperature of 60-70℃, and then cool and adjust the pH to neutral to obtain the final product.

8. A compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 6, characterized in that, The preparation steps of the bioactivated organic carrier include: Mix well-rotted organic fertilizer with mineral-derived potassium humate, add an activator to adjust the moisture content, and ferment at a constant temperature of 30-35℃ for 24-36 hours. After fermentation, add natural synergistic components and mix thoroughly; The activator is a brown sugar solution or an aqueous solution of corn steep liquor powder.

9. A compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 6, characterized in that, The preparation steps of the compound functional bacterial powder include: Each single strain was subjected to liquid fermentation. After adding a protectant to the fermentation broth, it was spray-dried at an inlet air temperature of 130-140℃ to obtain powders of each single strain. Mix the individual strain powders in proportion and add diatomaceous earth dispersant; The protective agent includes trehalose and skim milk powder.

10. A compound microbial fertilizer for simultaneously controlling root-knot nematodes and soil-borne fungal diseases according to claim 6, characterized in that, In step S1, the amount of the modified slow-release adhesive sprayed accounts for 40%-50% of the total amount of adhesive, and the hot air purging temperature is 35-42℃. In step S3, the drying is low-temperature fluidized bed drying or low-temperature drying, with the inlet air temperature controlled at 35-40℃ and the drying time being 30-60 minutes.