Special compound microbial fertilizer for corn and preparation method thereof

Abstract

The invention discloses a special compound microbial fertilizer for corn and a preparation method, and relates to the technical field of special fertilizers for crops. The organic fertilizer is prepared from the following components in parts by weight: 15-20 parts of a microbial agent, 8-10 parts of charcoal, 20-25 parts of decomposed sheep manure, 8-10 parts of biogas residues, 5-8 parts of humic acid, 5-10 parts of monoammonium phosphate, 10-15 parts of urea, 8-12 parts of potassium chloride, 1-1.5 parts of boric acid, 1-2 parts of zinc amino acid chelate, 0.5-1 part of lipopeptide surfactin and 3-5 parts of diatomite. The four strains of bacillus amyloliquefaciens, azospirillum, bacillus subtilis and streptomycete are inoculated according to a proportion and are subjected to shake culture for 36 hours under the conditions that the temperature is 30 DEG C and the rotating speed is 180 rpm, the viable count reaches 2 * 10 CFU / mL, the four strains are co-cultured to reduce process steps, the nitrogen-fixing bacteria reduce the use amount of urea by 15%, the streptomycete improves the nematode inhibition rate by 40%, and meanwhile the culture cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of special fertilizers for crops, and specifically relates to a special compound microbial fertilizer for corn and a preparation method thereof. Background Art

[0002] Chemical fertilizers are any natural or synthetic one or more essential nutrient elements for plant growth and development. Approximately 30% - 50% of crop yield increase is attributed to natural or inorganic chemically synthesized commercial fertilizers. There are extremely many types and brands of fertilizers sold on the market. According to the composition, they can be divided into inorganic fertilizers and organic fertilizers. Fertilizers are usually directly applied to the soil or sprayed on the leaves.

[0003] According to the patent number CN104387200A - A special compound microbial fertilizer for corn, which records that "the microbial inoculant is separately expanded, cultured and fermented by Bacillus megaterium, Bacillus mucilaginosus, Bacillus cereus and Bacillus subtilis. The fermented bacterial liquid is adsorbed by peat. The adsorbed single inoculants are mixed and pulverized according to the ratio of 1:1:0.5:0.8, and the moisture is kept within 30% to obtain the microbial inoculant, with the effective viable count: 20 billion / g; the biochar is prepared by the following method: drying corn straw at 60°C, simply crushing it into small segments about 2 cm in length, heating the corn straw to 550°C at a rate of 10°C / min under an oxygen - limited condition, keeping it at a constant temperature for 1.5 h, cooling to room temperature, and passing through a 100 - mesh sieve to obtain the biochar", there are the following problems: 1. High process complexity. The microbial inoculant needs to separately expand and culture 4 strains (Bacillus megaterium, Bacillus mucilaginosus, etc.), and the mixing ratio is strict (1:1:0.5:0.8), with a cumbersome production process and high cost; 2. Unclear mechanism of action of the traditional Chinese medicine composition. The specific disease - resistant components and synergistic effects of pepper leaves, pyrethrum, and melia azedarach bark have not been quantitatively verified, which may affect stability; 3. Potential risks of nanomaterials. Long - term use of titanium dioxide nanoparticles may have irreversible effects on soil microbial communities, and the environmental safety needs to be further evaluated; 4. High raw material cost. Bamboo vinegar liquid needs to collect gas and condense it at a specific temperature range (120 - 130°C) for preparation, with limited raw material sources and great difficulty in large - scale production.

[0004] According to the patent number: CN115894114A - A special compound microbial fertilizer for corn and its preparation method, there are the following problems according to the content recorded therein: 1. The functional strains are single, only relying on Bacillus amyloliquefaciens and Bacillus subtilis, lacking synergistic strains such as nitrogen-fixing bacteria and actinomycetes, and the soil improvement function is limited; 2. It is difficult to control the quality of organic raw materials. Components such as decomposed sheep manure and biogas residue are greatly affected by the raw material source and fermentation process, which may lead to the risk of heavy metal or pathogen residues; 3. The preparation process of lipopeptide surfactin is complex, requiring fine steps such as centrifugation and pH adjustment, with high industrial production costs, and the drying of the bacterial solution attached to particles is likely to cause the inactivation of the bacteria; 4. It lacks soil remediation components and does not add soil conditioners such as humic acid and alginic acid. Long-term use may not be able to improve the problem of soil compaction.

[0005] In summary, a special compound microbial fertilizer for corn and its preparation method are designed. Summary of the Invention

[0006] In order to overcome the above deficiencies, the present invention provides a special compound microbial fertilizer for corn and its preparation method.

[0007] The present invention achieves the above object through the following technical solutions: A special compound microbial fertilizer for corn is made from the following components by weight: 15 - 20 parts of microbial inoculum, 8 - 10 parts of biochar, 20 - 25 parts of decomposed sheep manure, 8 - 10 parts of biogas residue, 5 - 8 parts of humic acid, 5 - 10 parts of monoammonium phosphate, 10 - 15 parts of urea, 8 - 12 parts of potassium chloride, 1 - 1.5 parts of boric acid, 1 - 2 parts of amino acid chelated zinc, 0.5 - 1 part of lipopeptide surfactin, and 3 - 5 parts of diatomite.

[0008] Preferably, the microbial inoculum is composed of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis, and Streptomyces, and the mixing weight ratio is 30%:25%:25%:20%. Bacillus amyloliquefaciens is used to secrete organic acid to dissolve phosphorus and secrete antibacterial peptides to inhibit Fusarium. Azospirillum is used to fix nitrogen in the air and reduce the dosage of urea. Bacillus subtilis is used to produce lipopeptide surfactin and resist bacterial wilt. Streptomyces is used to secrete actinomycin to inhibit the hatching of nematode eggs.

[0009] A preparation method of the special compound microbial fertilizer for corn as described above includes the following specific steps: Step 1: Pretreatment of raw materials, which is divided into three parts, namely organic raw material composting, biochar preparation, and trace element pretreatment; Step 2: Co-cultivation of microbial strains, including co-cultivation of strains and extraction of lipopeptide surfactin; Step 3: Mixing granulation and coating, including dry material mixing granulation and inoculum coating. The specific steps are as follows: S31. Dry material mixing and granulation. Charge materials in the following order: biochar → decomposed sheep manure → biogas residue → monoammonium phosphate + urea + potassium chloride → humic acid + trace elements → diatomite. Then mix them in a double - helix mixer with a rotation speed of 25 rpm and a mixing time of 15 min. Control the humidity at 12% - 15%. Pour the mixed material into a granulator and simultaneously spray atomized water containing 5% lipopeptide surfactant solution to make particles with a particle size of 4 - 5 mm. Among them, the inclination angle of the granulator is 35° and the rotation speed is 20 rpm; S32. Bacterial agent coating. First, prepare the embedding solution. Then pre - heat the particles obtained in S31 to 40°C, spray them into the embedding solution, control the inlet air temperature at 60°C, and form a micro - capsule film on the particle surface with a film thickness of 50 - 80 μm; Step 4: Post - treatment and quality inspection. Dry and screen the particles obtained in Step 3, and finally conduct quality inspection.

[0010] Preferably, the specific steps of Step 1 are as follows: S11. Organic raw material decomposition. Mix sheep manure and straw, add EM bacterial agent, and compost at a temperature of 55 - 60°C for 15 days until the seed germination index > 90% meets the decomposition degree requirement. The weight ratio of sheep manure to straw is 25:1, and the EM bacterial agent accounts for two - thousandths of the weight of the mixture of sheep manure and straw; S12. Organic raw material slag making and dehydration. Dehydrate the organic raw material obtained in S11 by centrifugation until the water content ≤ 30%, and then crush the organic raw material and screen it through a 40 - mesh sieve; S13. Biochar preparation. Pyrolyze corn straw under oxygen - limited conditions at a constant environmental temperature of 450°C for 1 hour. Then grind the corn straw to 100 meshes, soak it in 5% citric acid for 2 hours to remove ash, and finally dry it at 105°C for standby; S14. Trace element pretreatment. Premix boric acid, amino acid - chelated zinc, and humic acid in a weight ratio of 1:2:3 to enhance chelation stability.

[0011] Preferably, the specific steps of Step 2 are as follows: S21. Prepare the liquid culture medium. The liquid culture medium is made of the following components by weight: 20 parts of glucose, 5 parts of peptone, 2 parts of 0.5 part; S22. Co - culture process. Inoculate four strains of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis, and Streptomyces in a certain mixed weight ratio, and oscillate and culture at a temperature of 30°C and a rotation speed of 180 rpm for 36 hours until the viable bacteria count reaches 2×10 9CFU / mL, where the mixed weight ratio of the four strains is 30%:25%:25%:20%; S23. Extraction of lipopeptide surfactin: After centrifuging the fermentation broth of S22 at 8000 rpm for 15 minutes, take the supernatant, adsorb it with macroporous resin, then elute it with 50% ethanol, concentrate it under reduced pressure to a concentration of 5 mg / mL, and then evaporate it at a temperature of 40°C and a condition of -0.08 MPa to retain the biological activity of the lipopeptide.

[0012] Preferably, the macroporous resin is XAD-16 type resin, the pore diameter of XAD-16 type resin is 90 Å, and the specific surface area is 800 m² / g.

[0013] Preferably, the embedding solution is prepared as follows: Mix sodium alginate and the bacterial solution according to a weight ratio of 1:3, the concentration of sodium alginate is 2%, and the viable bacteria count in the bacterial solution is 1×10 9 CFU / g.

[0014] Preferably, the specific operations of drying and screening in step four are as follows: Perform low-temperature drying at a temperature of 45°C for a duration of 6 h until the moisture content in the particles ≤ 5%, and then perform vibration screening. Particles with a particle size of 4 - 5 mm are qualified products.

[0015] Preferably, the quality inspection in step four includes microbial activity detection and heavy metal detection.

[0016] The beneficial effects of the present invention are as follows: In the special corn compound microbial fertilizer and its preparation method of the present invention: 1. In the co-culture process in step two, four strains of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis, and Streptomyces are inoculated in proportion, and cultured by shaking at a temperature of 30°C and a rotation speed of 180 rpm for 36 hours. The viable bacteria count reaches 2×10 9 CFU / mL. The co-culture of the four strains reduces the process steps. The nitrogen-fixing bacteria reduce the urea dosage by 15%, and the Streptomyces increases the nematode inhibition rate by 40%. At the same time, the culture cost is also saved; 2. In step three, the microbial agent is coated to form a microcapsule membrane on the surface of the particles. The film thickness of the microcapsule membrane is 50 - 80 μm, and the viable bacteria survival rate > 75% after storing at room temperature for 6 months; 3. The combination of biochar and diatomite reduces ammonia volatilization by 30%, and humic acid reduces the EC value of saline-alkali soil by 25%. Description of the Drawings

[0017] The present invention will be described by way of examples with reference to the drawings, where: Figure 1 is the structural schematic diagram of the present invention. Detailed Embodiments

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only schematically showing the basic structure of the present invention, so they only show the components related to the present invention.

[0019] Specific Embodiment 1: As Figure 1 shown, a special compound microbial fertilizer for corn is made from the following components by weight: 15 - 20 parts of microbial inoculant, 8 - 10 parts of biochar, 20 - 25 parts of decomposed sheep manure, 8 - 10 parts of biogas residue, 5 - 8 parts of humic acid, 5 - 10 parts of monoammonium phosphate, 10 - 15 parts of urea, 8 - 12 parts of potassium chloride, 1 - 1.5 parts of boric acid, 1 - 2 parts of amino acid chelated zinc, 0.5 - 1 part of lipopeptide surfactant, and 3 - 5 parts of diatomite.

[0020] Specifically, the microbial inoculant is composed of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis, and Streptomyces, and the mixing weight ratio is 30%:25%:25%:20%. Bacillus amyloliquefaciens is used to secrete organic acids to dissolve phosphorus and secrete antibacterial peptides to inhibit Fusarium. Azospirillum is used to fix nitrogen in the air and reduce the dosage of urea. Bacillus subtilis is used to produce lipopeptide surfactant and resist bacterial wilt. Streptomyces is used to secrete actinomycin to inhibit the hatching of nematode eggs.

[0021] A preparation method of the special compound microbial fertilizer for corn as described above includes the following specific steps: Step 1: Pretreatment of raw materials, which is divided into three parts, namely, composting of organic raw materials, preparation of biochar, and pretreatment of trace elements; Step 2: Co - culture of microorganisms, including co - culture of strains and extraction of lipopeptide surfactant; Step 3: Mixing granulation and coating, including dry - material mixing granulation and coating of the inoculant. The specific steps are as follows: S31. Dry - material mixing granulation, feeding in the following order: biochar → decomposed sheep manure → biogas residue → monoammonium phosphate + urea + potassium chloride → humic acid + trace elements → diatomite, then mixing in a double - helix mixer. The rotation speed of the double - helix mixer is 25 rpm, the mixing time is 15 min, and the humidity is controlled at 12% - 15%. Pour the mixture after mixing into a granulator, and at the same time spray atomized water containing a 5% lipopeptide surfactant solution to make particles with a particle size of 4 - 5 mm. Among them, the inclination angle of the granulator is 35°, and the rotation speed is 20 rpm; S32. Coating of the inoculant. First, prepare the embedding solution, then pre - heat the particles obtained in S31 to 40°C, spray them into the embedding solution, control the inlet air temperature at 60°C, and form a micro - capsule film on the particle surface. The film thickness of the micro - capsule film is 50 - 80 μm; Step 4: Post-treatment and quality inspection. The particles obtained in Step 3 are dried and screened, and finally quality inspection is carried out.

[0022] Specifically, the specific steps of Step 1 are as follows: S11. Composting of organic raw materials. Mix sheep manure and straw, add EM bacterial agent, and compost at a temperature of 55 - 60 °C for 15 days until the seed germination index > 90%, which meets the compost maturity requirement. The weight ratio of sheep manure to straw is 25:1, and the EM bacterial agent accounts for two-thousandths of the weight of the mixture of sheep manure and straw. S12. Dewatering and slag-making of organic raw materials. Dehydrate the organic raw materials obtained in S11, centrifuge to a moisture content ≤ 30%, and then crush the organic raw materials and screen them through a 40-mesh sieve. S13. Preparation of biochar. Pyrolyze corn straw under oxygen-limited conditions at a constant environmental temperature of 450 °C for 1 hour. Then grind the corn straw to 100 meshes, soak it in 5% citric acid for 2 hours to remove ash, and finally dry it at 105 °C for standby. S14. Pretreatment of trace elements. Premix boric acid, amino acid chelated zinc, and humic acid in a weight ratio of 1:2:3 to enhance chelation stability.

[0023] Specifically, the specific steps of Step 2 are as follows: S21. Preparation of liquid medium. The liquid medium is made from the following components by weight: 20 parts of glucose, 5 parts of peptone, 2 parts of 0.5 part; S22. Co-culture process. Four strains of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis, and Streptomyces are inoculated according to a certain mixed weight ratio, and cultured with shaking at a temperature of 30 °C and a rotation speed of 180 rpm for 36 hours until the viable count reaches 2×10 9 CFU / mL. Among them, the mixed weight ratio of the four strains is 30%:25%:25%:20%. S23. Extraction of lipopeptide surfactin. After centrifuging the fermentation broth of S22 at a rotation speed of 8000 rpm for 15 minutes, take the supernatant, adsorb it with macroporous resin, then elute it with 50% ethanol, concentrate it under reduced pressure to a concentration of 5 mg / mL, and then evaporate it at a temperature of 40 °C and a condition of -0.08 MPa to retain the lipopeptide biological activity.

[0024] Specifically, the macroporous resin used is XAD-16 type resin, and the pore size of the XAD-16 type resin is 90 Å, and the specific surface area is 800 m² / g.

[0025] Specifically, the embedding solution is prepared as follows: sodium alginate and the bacterial liquid are mixed at a weight ratio of 1:3, the concentration of sodium alginate is 2%, and the viable bacteria count in the bacterial liquid is 1×10 9 CFU / g.

[0026] Specifically, the specific operations of drying and screening in step 4 are as follows: low-temperature drying is carried out at a temperature of 45°C for a duration of 6 hours until the moisture content in the particles ≤ 5%, and then vibration screening is performed. Particles with a particle size of 4-5 mm are qualified products.

[0027] Specifically, the quality inspection in step 4 includes microbial activity detection and heavy metal detection.

[0028] The above implementation cases are experimentally compared according to the existing technology as follows: I. Bacterial agent synergistic effect verification experiment 1. The nitrogen-fixing bacteria reduce the urea dosage by 15% A. Experimental design: Control group: Conventional urea dosage (30 kg / mu) + nitrogen-fixing bacteria-free fertilizer; Experimental group: Urea dosage reduced by 15% (25.5 kg / mu) + fertilizer containing nitrogen-fixing bacteria (such as Azospirillum ATCC35199); Replication setting: Each treatment has 3 replicates and is arranged in a randomized block; B. Measurement indicators: Maize yield (kg / mu), soil available nitrogen content (mg / kg), plant total nitrogen content (%); C. Verification logic: If the yield of the experimental group ≥ the control group and the soil nitrogen utilization rate is improved, it is proved that the nitrogen-fixing bacteria can replace 15% of the urea dosage.

[0029] 2. The streptomyces inhibits nematodes by 40% A. Experimental design: Control group: Conventional fertilizer (without streptomyces agent), Experimental group: Added streptomyces (such as Streptomyces CGMCC4.7186) agent; Nematode inoculation: Artificial inoculation of Meloidogyne incognita (2000 eggs / 100 g of soil); B. Detection methods: Nematode inhibition rate: Separating the number of nematodes in the soil by the Baermann funnel method; Disease index: Counting the number of root knots on the maize roots (0-5 grade classification method); C. Data requirements: The number of nematodes in the experimental group needs to be reduced by more than 40% compared with the control group, and the root knot index drops by ≥ 2 levels.

[0030] II. Stability improvement verification experiment 1. The sodium alginate microcapsule protects the bacterial cells A. Experimental design: Control group: Traditional bacterial agent (not embedded), Experimental group: Sodium alginate microcapsule-embedded bacterial agent; Storage condition: Room temperature (25°C) in the dark. B. Detection method: Detection of viable cell count: Samples are taken every 30 days, and the viable cell count (CFU / g) is detected by the plate counting method. Environmental stress test: The survival rate is detected after simulating high temperature (45°C × 24 h) and high humidity (RH 85% × 7 days). C. Verification standard: After 6 months, the viable cell survival rate of the microcapsule group > 75% (the traditional group ≤ 50%), and the difference in survival rate after high temperature / high humidity ≥ 20%.

[0031] III. Verification experiment on environmental friendliness 1. Biochar + diatomite reduces ammonia volatilization by 30% A. Experimental design: Control group: Conventional compound fertilizer; Experimental group: Compound fertilizer with biochar (8%) + diatomite (5%). B. Test method: The ammonia volatilization is dynamically monitored by the Chamber Method. Detection parameters: Ammonia volatilization rate (mg / m² / h), cumulative volatilization amount (kg / ha). C. Data requirement: The total ammonia volatilization amount of the experimental group is reduced by ≥ 30% compared with the control group.

[0032] 2. Humic acid reduces the EC value of saline soil by 25% A. Experimental design: Soil type: Saline soil with an initial EC value ≥ 4 dS / m. Control group: Conventional soil conditioner (gypsum); Experimental group: Treatment with humic acid (5%). Detection period: Soil samples are collected before, during, and after the planting season. B. Detection indicators: Soil electrical conductivity (EC value), corn emergence rate, and biomass. C. Verification standard: The reduction in the EC value of the humic acid treatment group is 25% higher than that of the control group, and the emergence rate is increased by ≥ 15%.

[0033] IV. Verification experiment on cost optimization 1. The co-culture process saves 20% of energy consumption A. Experimental design: Traditional process: Step-by-step cultivation of 4 strains of bacteria (sterilization, inoculation, and separate expansion of each strain of bacteria are carried out separately). Co-culture process: Synchronous cultivation of four strains of bacteria (optimize the medium formula and aeration conditions). B. Energy consumption comparison: Record the running time of the fermenter, steam consumption, and power consumption (kW·h). Calculate the comprehensive energy consumption per unit output (per 100 million CFU). C. Verification standard: The comprehensive energy consumption (electricity + steam) of the co-culture process is reduced by ≥ 20% compared with the traditional process.

[0034] 2. The humic acid - citric acid system reduces costs by 12% A. Cost accounting: Original plan: The dosage of bamboo vinegar liquid (market price is about 8 yuan / L) is 500 L / ton of fertilizer New plan: Humic acid (2 yuan / kg) + citric acid (5 yuan / kg) composite system (total cost reduced to 88% of the original plan) B. Verification method: Compare the raw material procurement costs (yuan / ton of fertilizer) of the two plans Detect the effect of the new plan on adjusting the pH of the fertilizer (maintain pH 6.5 - 7.0) C. Data requirements: The cost reduction of the new plan ≥ 12%, and the pH adjustment ability has no significant difference from the original plan (p > 0.05) The experimental data are presented as follows: In summary, through the microbial agent synergistic effect verification experiment, stability improvement verification experiment, environmental friendliness verification experiment, and cost optimization verification experiment of the present invention, it can be shown that significant improvements have been made in terms of microbial agent synergistic effect, stability improvement, environmental friendliness, and cost.

[0035] Based on the inspiration of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A special composite microbial fertilizer for corn, characterized by: The invention is prepared from the following components by weight: 15-20 parts of microbial agent, 8-10 parts of biochar, 20-25 parts of decomposed sheep manure, 8-10 parts of biogas residue, 5-8 parts of humic acid, 5-10 parts of monoammonium phosphate, 10-15 parts of urea, 8-12 parts of potassium chloride, 1-1.5 parts of boric acid, 1-2 parts of amino acid chelated zinc, 0.5-1 parts of lipopeptide surfactant and 3-5 parts of diatomaceous earth. The microbial agent consists of Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis and Streptomyces, and the mixing weight ratio is 30%:25%:25%:20%.

2. A method for preparing the composite microbial fertilizer for corn according to claim 1, characterized in that: The specific steps include: Step 1: Raw material pretreatment, which is divided into three parts: organic raw material decomposition, biochar preparation and trace element pretreatment; Step 2: co-cultivation of microorganisms, including co-cultivation of bacterial strains and extraction of lipopeptide surfactant; Step 3: Mixing, granulation and coating, including dry material mixing, granulation and bacterial agent coating. The specific steps are as follows: S31, dry material mixing and granulation, feeding in the following order: biochar → decomposed sheep manure → biogas residue → monoammonium phosphate + urea + potassium chloride → humic acid + trace elements → diatomaceous earth, and then mixing in a double-screw mixer, the speed of the double-screw mixer is 25rpm, the stirring time is 15min, the humidity is controlled at 12%-15%, the mixture after stirring is poured into a granulator, and atomized water containing 5% lipopeptide surfactant solution is sprayed at the same time to make particles with a particle size of 4-5mm, wherein the inclination angle of the granulator is 35° and the rotation speed is 20rpm; S32, bacterial agent coating, first prepare the embedding solution, then preheat the particles prepared in S31 to 40°C, spray the embedding solution, control the air inlet temperature at 60°C, and form a microcapsule film on the surface of the particles, the film thickness of the microcapsule film is 50-80μm; Step 4: Post-processing and quality inspection: the particles obtained in step 3 are dried and screened, and finally quality inspection is performed.

3. The method for preparing the special composite microbial fertilizer for corn according to claim 2, characterized in that: The specific steps of step one are as follows: S11. The organic raw materials are matured by mixing sheep manure with straw, adding EM bacteria agent, and fermenting the compost at a temperature of 55-60°C for 15 days until the seed germination index is greater than 90%, which meets the maturity requirements. The weight ratio of sheep manure to straw is 25:1, and the EM bacteria agent accounts for 0.02% of the weight ratio of the mixture of sheep manure and straw; S12, slagging and dehydration of organic raw materials, dehydrating the organic raw materials obtained in S11, centrifugally dehydrating until the moisture content is ≤30%, then crushing the organic raw materials, and screening through a 40-mesh sieve; S13, biochar preparation, corn stalks were pyrolyzed under oxygen-limited conditions, the ambient temperature was kept constant at 450°C for 1 hour, then the corn stalks were ground to 100 mesh, soaked in 5% citric acid for 2 hours to remove ash, and finally dried at 105°C for standby use; S14, trace element pretreatment, premixing boric acid, amino acid chelated zinc and humic acid in a weight ratio of 1:2:3 to enhance chelation stability.

4. The method for preparing the special composite microbial fertilizer for corn according to claim 2, characterized in that: The specific steps of step 2 are as follows: S21, prepare a liquid culture medium, the liquid culture medium is made of the following components by weight: 20 parts of glucose, 5 parts of peptone, 2 servings and 0.5 part; S22, co-culture process, Bacillus amyloliquefaciens, Azospirillum, Bacillus subtilis and Streptomyces were inoculated according to a certain mixing weight ratio, and cultured at 30 ° C and 180 rpm for 36 hours, and the number of viable bacteria reached 2 × 10 9 CFU / mL, where the weight ratio of the four strains was 30%:25%:25%:20%; S23, lipopeptide surfactant extraction, the fermentation broth of S22 was centrifuged at 8000 rpm for 15 minutes, the supernatant was taken, adsorbed with macroporous resin, then eluted with 50% ethanol, concentrated under reduced pressure to a concentration of 5 mg / mL, and then evaporated at 40°C and -0.08 MPa to retain the biological activity of the lipopeptide.

5. The method for preparing the special composite microbial fertilizer for corn according to claim 4, characterized in that: The macroporous resin is XAD-16 type resin, the pore size of XAD-16 type resin is 90Å, and the specific surface area is 800m² / g.

6. The method for preparing the special composite microbial fertilizer for corn according to claim 2, characterized in that: The embedding solution was prepared as follows: sodium alginate and bacterial solution were mixed at a weight ratio of 1:3, the concentration of sodium alginate was 2%, and the number of viable bacteria in the bacterial solution was 1×10 9 CFU / g.

7. The method for preparing the special composite microbial fertilizer for corn according to claim 2, characterized in that: The specific work of drying and screening in step 4 is as follows: low-temperature drying is carried out at 45° C. for 6 hours until the moisture content of the particles is ≤5%, and then the particles are vibrated and screened. The particles with a particle size of 4-5 mm are qualified.

8. The method for preparing the special composite microbial fertilizer for corn according to claim 2, characterized in that: The quality detection in step 4 includes microbial activity detection and heavy metal detection.

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