A kind of composite microbial fertilizer for soybean and preparation method thereof

Abstract

The invention belongs to the technical field of composite fertilizers, and particularly relates to a composite microbial fertilizer for soybeans and a preparation method thereof; the composite microbial fertilizer for soybeans is composed of the following percentage components: 17-20% soybean meal powder fermentation liquid, 15-20% egg shell powder, 12-14% humic acid, 6% sodium selenite, 6-8% potassium sulfate, 12-16% urea, 6-8% calcium dihydrogen phosphate, 6-8% potassium dihydrogen phosphate, 1-2% chelated zinc, 1-2% chelated iron, 1-2% chelated copper, 1-2% indoleacetic acid, and 1-2% plant growth factor; the composite microbial fertilizer for soybeans prepared by the invention can improve soil structure, improve soil water and nutrient retention capacity, help improve soil microbial activity, promote organic matter decomposition, enhance the health of soil ecosystems, increase cation exchange capacity in soil, enable soybeans to absorb nutrients more effectively, and promote soybean root growth; the composite microbial fertilizer for soybeans prepared by the invention contains rich nitrogen, phosphorus, potassium and trace elements, and can provide balanced nutrition required for soybean growth.

Description

Technical Field

[0001] The invention belongs to the technical field of compound fertilizers, and in particular relates to a special compound microbial fertilizer for soybeans and a preparation method thereof. Background Art

[0002] Soybean is an important crop with rich nutritional value and wide economic use. Soybean is rich in protein and oil, and is an important source of vegetable protein. It is widely used in human food and animal feed. At the same time, soybean oil is one of the most commonly used vegetable oils in the world, used in cooking and industrial production. Compound fertilizer is a fertilizer containing multiple nutrients, mainly used to increase crop growth and yield. The use of compound fertilizer can reduce the number of fertilization and labor intensity, improve fertilization efficiency, and thus reduce the impact on the environment.

[0003] The growth of soybeans requires a specific combination of nutrients, including nitrogen, phosphorus, potassium and trace elements. Chinese patent publication number CN112573962A discloses a compound fertilizer containing chelated trace elements and a preparation method thereof. The compound fertilizer cannot provide the balanced nutrition required for soybean growth during application, and the yield-increasing effect during soybean planting is not obvious. Chinese patent publication number CN106673744A discloses a special fertilizer for soybeans and an application method thereof. The fertilizer contains a large amount of selenium. Excessive use will lead to soil acidification, thereby affecting soil health and microbial activity. Long-term use will lead to nitrogen loss in the soil, causing eutrophication of nearby water bodies, and further affecting the soil ecology of the entire region.

[0004] In view of the above technical defects, a solution is now proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a special composite microbial fertilizer for soybean and a preparation method thereof, which contains a specific nutrient combination required for soybean growth and has an obvious yield-increasing effect after use without affecting the soil ecological environment of the region.

[0006] To achieve the above purpose, the present invention adopts the following technical scheme: a special composite microbial fertilizer for soybeans is composed of the following percentage components: 10-20% soybean meal powder fermentation liquid, 10-20% egg shell powder, 10-15% humic acid, 6-10% sodium selenite, 6-10% potassium sulfate, 12-20% urea, 6-10% monocalcium phosphate, 6-10% monopotassium phosphate, 1-2% chelated zinc, 1-2% chelated iron, 1-2% chelated copper, 1-2% indoleacetic acid, 1-2% plant growth factor;

[0007] Furthermore, the method for preparing the soybean meal powder fermentation liquid comprises the following steps:

[0008] A1: Add soybean meal powder into the degradation pool, add pure water and lactic acid bacteria, add 10kg lactic acid bacteria per ton of soybean meal powder, stir evenly, and degrade for 15-20 days;

[0009] A2: Add alumina to the degradation tank for flocculation and sedimentation. Stir for 1-2 hours and then let it settle. The sedimentation time is 2-4 hours. After sedimentation, remove the solid precipitate.

[0010] A3: Add the solid precipitate to the degradation tank repeatedly, repeat steps A1-A2, and repeat 1-2 times;

[0011] A4: After sedimentation, add the mixture to a coarse material filter with a 200-mesh filter screen, and use physical filtration to remove solid particles to obtain a primary fermentation liquid of soybean meal powder;

[0012] A5: Add the primary fermentation liquid of soybean meal powder into the homogenizer, set the speed to 1000-1800rpm, stir for 1-2h, stir it evenly to form a stable suspension, and ensure the stability of the physical properties of the material;

[0013] A6: Add the homogenized soybean meal primary fermentation liquid into the fermentation tank, adjust the temperature of the fermentation tank to 50°C, adjust the speed of the fermentation tank stirrer to 800-1000rpm, stir for 0.5-1h, then add yeast, the mass ratio of yeast to soybean meal primary fermentation liquid is 100:1;

[0014] A7: Raise the temperature of the fermentation tank to 75-85°C, adjust the speed of the fermentation tank stirrer to 600-800rpm, and the oxygen content to 5%. Ferment for 15-20 days to obtain soybean meal fermentation liquid;

[0015] Furthermore, a method for preparing a special composite microbial fertilizer for soybeans comprises the following steps:

[0016] S1: soybean meal fermentation liquid, egg shell powder, humic acid, potassium sulfate, urea, calcium dihydrogen phosphate, potassium dihydrogen phosphate and sodium selenite are fed into a mixing and stirring device, the speed of the mixing and stirring device is set to 200-300rpm, to obtain a mixed raw material, and then fermentation bacteria are added, 0.5-1kg per ton of mixed raw material, the fermentation bacteria are streptomyces, alcohol yeast, lactic acid bacteria and nitrifying bacteria, and the mass ratio is 3:2:2:3, the moisture content of the raw material is roughly adjusted to 60-65%, and stirred for 1-2h;

[0017] S2: The mixed raw materials are transported to the fermentation workshop by a loader to form a fermentation pile, and the fermentation is carried out for 40-60 days. The pile is turned every 2 days, and water is continuously added to control the moisture content to 60-65%. The temperature of the fermentation workshop is adjusted to control the temperature of the fermentation pile to 50-65°C, and ammonia water is used to adjust the pH of the fermentation pile to 6.8-7.5. After the fermentation is completed, a semi-finished fertilizer is obtained;

[0018] S3: Use a temperature measuring gun to measure the surface temperature of the semi-finished fertilizer product. After the temperature drops to 40-45°C, add rhizobia and phosphate-solubilizing bacteria. Add 50-100 g per ton of semi-finished fertilizer product, where the mass ratio of rhizobia to phosphate-solubilizing bacteria is 1:1.

[0019] S4: sending the semi-finished fertilizer product into a granulator for granulation, setting the particle size to 0.32-1.27 cm, and then sending it into a dryer for drying for 2-3 hours to obtain fertilizer granules, adding the fertilizer granules into a mixing and stirring device and adding chelated zinc, chelated iron, chelated copper, indoleacetic acid and plant growth factor, setting the rotation speed to 200-300rpm, stirring for 1-2 hours, and after the stirring is completed, packaging it into a warehouse to obtain a special composite microbial fertilizer for soybeans.

[0020] Furthermore, the chelated zinc is EDTA chelated zinc, the chelated iron is EDDHA chelated iron, and the chelated copper is EDTA-Cu-6 which is fully soluble copper; the plant growth factors are glutamic acid, aspartic acid, proline and arginine in a ratio of 3:2:2:3.

[0021] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present invention are as follows: the soybean-specific composite microbial fertilizer prepared by the present invention can improve the soil structure, improve the soil's water and nutrient retention capacity, help to improve the activity of soil microorganisms, promote the decomposition of organic matter, enhance the health of the soil ecosystem, and increase the cation exchange capacity in the soil, so that soybeans can more effectively absorb nutrients, such as nitrogen, phosphorus, and potassium, which can promote the growth of soybean roots. At the same time, the present invention is rich in nitrogen, phosphorus, potassium and trace elements, and can provide the balanced nutrition required for soybean growth. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0023] The experimental methods in the following examples, unless otherwise specified, are conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0024] Example 1

[0025] 1: Add 20kg soybean meal powder into the degradation tank, add 100L pure water and 200g lactic acid bacteria, and degrade for 15 days;

[0026] 2: Add 5kg of alumina to the degradation tank for flocculation and sedimentation. Stir for 2 hours and then let it stand for 4 hours. After sedimentation, remove the solid precipitate.

[0027] 3: Add the solid precipitate to the degradation tank again, repeat steps A1-A2, and repeat twice;

[0028] 4: After sedimentation is completed, add it to the coarse material filter with a 200-mesh filter screen, and use physical filtration to remove solid particles to obtain 120L soybean meal powder primary fermentation liquid;

[0029] 5: Add the primary fermentation liquid of soybean meal powder into the homogenizer, set the speed to 1800rpm, stir for 1.5h, stir it evenly to form a stable suspension, and ensure the stability of the physical properties of the material;

[0030] 6: Add the homogenized soybean meal primary fermentation liquid into the fermentation tank, adjust the temperature of the fermentation tank to 50°C, adjust the speed of the fermentation tank stirrer to 800 rpm, stir for 1 hour, and then add 120g of yeast;

[0031] 7: Raise the temperature of the fermentation tank to 80° C., adjust the speed of the fermentation tank stirrer to 800 rpm, and the oxygen content to 5%, and ferment for 20 days to obtain the soybean meal powder fermentation liquid prepared in Example 1;

[0032] Table 1, reagent parameters used in Example 1

[0033] Drug Name source model parameter Soybean meal Shijiazhuang Jiunong Technology Co., Ltd. JN-01 1kg Lactic acid bacteria Shandong Runwo Biotechnology Co., Ltd. 2023928 1kg Alumina Shanghai Jinglian New Materials Co., Ltd. SJL 99.9% yeast Shandong Xinzhuoyuan Biotechnology Co., Ltd. 20200115 1kg

[0034] Example 2

[0035] 1: Add 100kg soybean meal powder into the degradation tank, add 500L pure water and 1kg lactic acid bacteria, and degrade for 20 days;

[0036] 2: Add 20kg of alumina to the degradation tank for flocculation and sedimentation. Stir for 2 hours and then let it stand for 3 hours. After sedimentation, remove the solid precipitate.

[0037] 3: Add the solid precipitate to the degradation tank again, repeat steps A1-A2, and repeat twice;

[0038] 4: After sedimentation is completed, add it to the coarse material filter with a 200-mesh filter screen, and use physical filtration to remove solid particles to obtain 580L soybean meal powder primary fermentation liquid;

[0039] 5: Add the primary fermentation liquid of soybean meal powder into the homogenizer, set the speed to 1800rpm, stir for 2h, stir it evenly to form a stable suspension, and ensure the stability of the physical properties of the material;

[0040] 6: Add the homogenized soybean meal primary fermentation liquid into the fermentation tank, adjust the temperature of the fermentation tank to 50°C, adjust the speed of the fermentation tank stirrer to 1000 rpm, stir for 0.5h, and then add 580g of yeast;

[0041] 7: Raise the temperature of the fermentation tank to 85° C., adjust the speed of the fermentation tank stirrer to 800 rpm, and the oxygen content to 5%, and ferment for 20 days to obtain the soybean meal powder fermentation liquid prepared in Example 2;

[0042] Table 2, reagent parameters used in Example 2

[0043] Drug Name source model parameter Lactic acid bacteria Shandong Runwo Biotechnology Co., Ltd. 2023928 1kg Alumina Shanghai Jinglian New Materials Co., Ltd. SJL 99.9% yeast Shandong Xinzhuoyuan Biotechnology Co., Ltd. 20200115 1kg

[0044] Example 3

[0045] S1: 40 kg of soybean meal fermentation liquid prepared in Example 1, 40 kg of egg shell powder, 28 kg of humic acid, 12 kg of potassium sulfate, 24 kg of urea, 12 kg of calcium dihydrogen phosphate, 12 kg of potassium dihydrogen phosphate and 12 kg of sodium selenite are fed into a mixing device, the speed of the mixing device is set to 200-300 rpm, and 180 kg of mixed raw materials are obtained, followed by adding 27 g of Streptomyces, 18 g of alcohol yeast, 18 g of lactic acid bacteria and 27 g of nitrifying bacteria, and the moisture content of the raw materials is roughly adjusted to 65%, and stirred for 2 hours;

[0046] S2: The mixed raw materials are transported to the fermentation workshop by a loader to form a fermentation pile, and the fermentation is carried out for 40 days. The pile is turned every 2 days, and water is continuously added to control the moisture content to 65%. The temperature of the fermentation workshop is adjusted to control the temperature of the fermentation pile to 50-65°C, and ammonia water is used to adjust the pH of the fermentation pile to 6.8-7.5. After the fermentation is completed, a semi-finished fertilizer is obtained;

[0047] S3: Use a temperature measuring gun to measure the surface temperature of the semi-finished fertilizer product, and add 10g of rhizobia and 10g of phosphate-solubilizing bacteria after the temperature drops to 42°C;

[0048] S4: The semi-finished fertilizer product is sent to a granulator for granulation, and the particle size is set to 0.32-1.27 cm. It is then sent to a dryer for drying for 3 hours to obtain fertilizer granules. The fertilizer granules are added to a mixing and stirring device and 4 kg EDTA chelated zinc, 4 kg EDDHA chelated iron, 4 kg EDTA-Cu-6, 4 kg indoleacetic acid, 1.2 kg glutamic acid, 0.8 kg aspartic acid, 0.8 kg proline, and 1.2 kg arginine are added. The speed is set to 300 rpm and stirred for 2 hours. After stirring, the composite microbial fertilizer prepared in Example 3 is obtained.

[0049] Table 3, reagent parameters used in Example 3

[0050] Drug Name source model parameter Humic acid Jinan Sirui Chemical Co., Ltd. 1688 100 mesh Potassium sulfate Lianyungang Guansu Industrial Co., Ltd. 7778-80-5 52% Urea Shandong Mingwei Chemical Co., Ltd. MW-010 80 mesh Calcium dihydrogen phosphate Jinan Gongchuang Biotechnology Co., Ltd. 7758-23-8 Gc6958 Potassium dihydrogen phosphate Henan Yupu Chemical Products Co., Ltd. 12-11-A 99% Streptomyces Dehe Mingxing Biotechnology Co., Ltd. 01-08 1kg Alcoholic yeast Shandong Xinzhuoyuan Biotechnology Co., Ltd. 20200115 1kg Lactic acid bacteria Shandong Runwo Biotechnology Co., Ltd. 2023928 1kg Nitrifying bacteria Foshan Sanzhong Environmental Protection Technology Co., Ltd. SZ-061 1.2kg EDTA chelated zinc Henan Shuangjie Chemical Co., Ltd. 12 99% EDDHA Chelated Iron Guangzhou Pure Beauty Chemical Co., Ltd. Fe-6 1kg EDTA-Cu-6 Fujian Wanguo Agricultural Materials Co., Ltd. FWf 15% Indoleacetic acid Shandong Hengke Biotechnology Co., Ltd. YG 98% Glutamate Shandong Daxu Bioengineering Co., Ltd. 102 99% Aspartic acid Wuhan Hongxing Biotechnology Co., Ltd. 56-84-8 99% Proline Jiangsu Yuanshengtong Bioengineering Co., Ltd. 374 99% Arginine Guangzhou Cresun Biotechnology Co., Ltd. 20113118 80 mesh Egg shell powder Lingshou County Jinyuan Mining Processing Plant 032015 1kg

[0051] Table 4, parameter table of compound fertilizer prepared in Example 3

[0052] project Total organic carbon Available nitrogen Available Phosphorus Available Potassium pH content 42% 2.1% 1.0% 1.7% 6.6 Effective proportion / 92% 44% 88% /

[0053] Example 4

[0054] 1: 34kg of soybean meal fermentation liquid prepared in Example 2, 30kg of egg shell powder, 24kg of humic acid, 16kg of potassium sulfate, 32kg of urea, 16kg of calcium dihydrogen phosphate, 16kg of potassium dihydrogen phosphate and 12kg of sodium selenite were fed into a mixing device, the speed of the mixing device was set to 200-300rpm, and 180kg of mixed raw materials were obtained, followed by adding 27g of Streptomyces, 18g of alcohol yeast, 18g of lactic acid bacteria and 27g of nitrifying bacteria, the moisture content of the raw material was roughly adjusted to 60%, the speed of the mixing device was set to 300rpm, and stirring was carried out for 2h;

[0055] 2: Use a loader to transport the mixed raw materials to the fermentation workshop and pile them into a fermentation pile. Ferment for 40 days, turn the pile every 2 days, continuously add water, control the moisture content to 60%, adjust the temperature of the fermentation workshop, control the temperature of the fermentation pile to 60°C, use ammonia water to adjust the pH of the fermentation pile to 6.8-7.5, and obtain a semi-finished fertilizer after fermentation;

[0056] 3: Use a temperature measuring gun to measure the surface temperature of the semi-finished fertilizer. When the temperature drops to 40°C, add 10g of rhizobia and 10g of phosphate-dissolving bacteria;

[0057] 4: The semi-finished fertilizer product is sent to a granulator for granulation, and the particle size is set to 0.32-1.27 cm. It is then sent to a dryer for drying for 3 hours to obtain fertilizer granules. The fertilizer granules are added to a mixing and stirring device and 4 kg EDTA chelated zinc, 4 kg EDDHA chelated iron, 4 kg EDTA-Cu-6, 4 kg indoleacetic acid, 1.2 kg glutamic acid, 0.8 kg aspartic acid, 0.8 kg proline, and 1.2 kg arginine are added. The speed is set to 300 rpm and stirred for 2 hours. After stirring, the composite microbial fertilizer prepared in Example 4 is obtained.

[0058] Table 5, reagent parameters used in Example 4

[0059] Drug Name source model parameter Humic acid Jinan Sirui Chemical Co., Ltd. 1688 100 mesh Potassium sulfate Lianyungang Guansu Industrial Co., Ltd. 7778-80-5 52% Urea Shandong Mingwei Chemical Co., Ltd. MW-010 80 mesh Calcium dihydrogen phosphate Jinan Gongchuang Biotechnology Co., Ltd. 7758-23-8 Gc6958 Potassium dihydrogen phosphate Henan Yupu Chemical Products Co., Ltd. 12-11-A 99% Streptomyces Dehe Mingxing Biotechnology Co., Ltd. 01-08 1kg Alcoholic yeast Shandong Xinzhuoyuan Biotechnology Co., Ltd. 20200115 1kg Lactic acid bacteria Shandong Runwo Biotechnology Co., Ltd. 2023928 1kg Nitrifying bacteria Foshan Sanzhong Environmental Protection Technology Co., Ltd. SZ-061 1.2kg EDTA chelated zinc Henan Shuangjie Chemical Co., Ltd. 12 99% EDDHA Chelated Iron Guangzhou Pure Beauty Chemical Co., Ltd. Fe-6 1kg EDTA-Cu-6 Fujian Wanguo Agricultural Materials Co., Ltd. FWf 15% Indoleacetic acid Shandong Hengke Biotechnology Co., Ltd. YG 98% Glutamate Shandong Daxu Bioengineering Co., Ltd. 102 99% Aspartic acid Wuhan Hongxing Biotechnology Co., Ltd. 56-84-8 99% Proline Jiangsu Yuanshengtong Bioengineering Co., Ltd. 374 99% Arginine Guangzhou Cresun Biotechnology Co., Ltd. 20113118 80 mesh Egg shell powder Lingshou County Jinyuan Mining Processing Plant 032015 1kg

[0060] Table 6, parameter table of compound fertilizer prepared in Example 4

[0061] project Total organic carbon Available nitrogen Available Phosphorus Available Potassium pH content 41% 2.3% 0.9% 1.8% 6.7 Effective proportion / 94% 45% 91% /

[0062] Comparative Example 1

[0063] A specific implementation mode 1 of the Chinese patent with publication number CN106673744A was selected as comparative example 1.

[0064] Comparative Example 2

[0065] Example 1 of the Chinese patent with publication number CN112573962A was selected as comparative example 2.

[0066] Film forming test:

[0067] Example 3, Example 4, Comparative Example 1 and Comparative Example 2 were added with water to prepare 0.1% foliar fertilizer, which was sprayed on soybean leaves. After 1 hour of spraying, the stomatal opening of the spinach leaves after the foliar fertilizer was sprayed was observed using an optical microscope, with clean water as a control;

[0068] Soil Porosity Test:

[0069] The experimental area is located in the experimental field of Yongqiao District, Suzhou City, Anhui Province. The experiment is carried out on soybeans. The seedlings are selected on March 27, 2024, transplanting is on May 4, and the initial harvest is on October 6.

[0070] The test was divided into 5 groups, and each group was set up with 3 areas to repeat the experiment, with an area of ​​10m*10m. A total of 15 areas were randomly distributed in the test field, and Example 3, Example 4, Comparative Example 1 and Comparative Example 2 were respectively configured as 400 times liquid and used agricultural water as the control group, sprayed once a week. Except for the different tested fertilizers, other agronomic measures were completely consistent. The soil porosity was determined by the ring knife method, and the calculation formula was: soil porosity = [1-(bulk density / specific gravity)] * 100%, where the soil specific gravity is 2.64g / cm 3 .

[0071] Table 8. Organic matter content of tested soil

[0072] project content Organic matter 14.02g / kg Total Phosphorus 0.85g / kg Total nitrogen 1.34g / kg Total Potassium 1.52g / kg Available Phosphorus 22.95mg / kg Fast-Acting Potassium 233.22mg / kg Fast-Acting Nitrogen 48.14mg / kg pH 8.12

[0073] Table 9, soil porosity test results

[0074] Grouping Total soil porosity Example 3 51.4% Example 4 51.6% Comparative Example 1 59.2% Comparative Example 2 48.7% Control group 44.3%

[0075] Soybean yield test:

[0076] According to the zoning principle, rice yields in each area are collected for yield testing

[0077] Table 10, soybean yield test results

[0078] Grouping Yield (kg / mu) Example 3 520±23.22 Example 4 514±24.45 Comparative Example 1 487±13.13 Comparative Example 2 479±12.17

[0079] According to the above performance test results, the compound fertilizers prepared in Example 3 and Example 4 have better soil porosity and field test results, among which the compound fertilizer prepared in Example 3 has the highest yield per mu.

[0080] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A composite microbial fertilizer for soybean, characterized in that: It is composed of the following percentage ingredients: 17-20% soybean meal fermentation liquid, 15-20% egg shell powder, 12-14% humic acid, 6% sodium selenite, 6-8% potassium sulfate, 12-16% urea, 6-8% monocalcium phosphate, 6-8% monopotassium phosphate, 1-2% chelated zinc, 1-2% chelated iron, 1-2% chelated copper, 1-2% indoleacetic acid, 1-2% plant growth factor; The method for preparing the soybean meal powder fermentation liquid comprises the following steps: A1: Add soybean meal powder into the degradation pool, add pure water and lactic acid bacteria, add 10kg lactic acid bacteria per ton of soybean meal powder, stir evenly, and degrade for 15-20 days; A2: Add alumina to the degradation tank for flocculation and sedimentation. Stir for 1-2 hours and then let it settle. The sedimentation time is 2-4 hours. After sedimentation, remove the solid precipitate. A3: Add the solid precipitate to the degradation tank repeatedly, repeat steps A1-A2, and repeat 1-2 times; A4: After sedimentation, add the mixture to a coarse material filter with a 200-mesh filter screen, and use physical filtration to remove solid particles to obtain a primary fermentation liquid of soybean meal powder; A5: Add the primary fermentation liquid of soybean meal powder into the homogenizer, set the speed to 1000-1800rpm, stir for 1-2h, stir it evenly to form a stable suspension, and ensure the stability of the physical properties of the material; A6: Add the homogenized soybean meal primary fermentation liquid into the fermentation tank, adjust the temperature of the fermentation tank to 50°C, adjust the speed of the fermentation tank stirrer to 800-1000rpm, stir for 0.5-1h, then add yeast, the mass ratio of yeast to soybean meal primary fermentation liquid is 100:1; A7: Raise the temperature of the fermentation tank to 75-85°C, adjust the speed of the fermentation tank stirrer to 600-800rpm, and the oxygen content to 5%. Ferment for 15-20 days to obtain soybean meal fermentation liquid; The chelated zinc is EDTA chelated zinc; The chelated iron is EDDHA chelated iron; The chelated copper is EDTA-Cu-6 which is fully soluble copper; The plant growth factors are glutamic acid, aspartic acid, proline and arginine in a ratio of 3:2:2:

3.

2. The method for preparing a special composite microbial fertilizer for soybean according to claim 1, characterized in that: The following steps are involved: S1: soybean meal fermentation liquid, egg shell powder, humic acid, potassium sulfate, urea, calcium dihydrogen phosphate, potassium dihydrogen phosphate and sodium selenite are fed into a mixing and stirring device, the speed of the mixing and stirring device is set to 200-300rpm, to obtain a mixed raw material, and then fermentation bacteria are added, 0.5-1kg per ton of mixed raw material, the fermentation bacteria are streptomyces, alcohol yeast, lactic acid bacteria and nitrifying bacteria, and the mass ratio is 3:2:2:3, the moisture content of the raw material is roughly adjusted to 60-65%, and stirred for 1-2h; S2: The mixed raw materials are transported to the fermentation workshop by a loader to form a fermentation pile, and the fermentation is carried out for 40-60 days. The pile is turned every 2 days, and water is continuously added to control the moisture content to 60-65%. The temperature of the fermentation workshop is adjusted to control the temperature of the fermentation pile to 50-65°C, and ammonia water is used to adjust the pH of the fermentation pile to 6.8-7.

5. After the fermentation is completed, a semi-finished fertilizer is obtained; S3: Use a temperature measuring gun to measure the surface temperature of the semi-finished fertilizer product. After the temperature drops to 40-45°C, add rhizobia and phosphate-solubilizing bacteria. Add 50-100 g per ton of semi-finished fertilizer product, where the mass ratio of rhizobia to phosphate-solubilizing bacteria is 1:

1. S4: sending the semi-finished fertilizer product into a granulator for granulation, setting the particle size to 0.32-1.27 cm, and then sending it into a dryer for drying for 2-3 hours to obtain fertilizer granules, adding the fertilizer granules into a mixing and stirring device and adding chelated zinc, chelated iron, chelated copper, indoleacetic acid and plant growth factor, setting the rotation speed to 200-300rpm, stirring for 1-2 hours, and after the stirring is completed, packaging it into a warehouse to obtain a special composite microbial fertilizer for soybeans.

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