A soil structure-improving and fertilizing compound fertilizer and its preparation method and application

Abstract

The present invention provides a soil structure improving and fertilizing compound fertilizer and a preparation method and application thereof. The raw materials for preparing the soil structure improving and fertilizing compound fertilizer include: modified polymer, livestock and poultry feces fermentation product, compound bacillus fermentation product, compound inorganic fertilizer, and organic plant residue. The present invention obtains the compound bacillus fermentation product through process fermentation, improves the activity and quantity of microorganisms, promotes the synergistic effect between different bacillus strains, makes the decomposition and conversion efficiency of insoluble phosphorus and potassium in the soil higher, can provide plants with more abundant absorbable nutrients, promotes the growth and development of plants, and improves the pore structure of the soil after mixing with modified polymer, livestock and poultry feces fermentation product, and organic plant residue, so that the soil can better retain moisture and enhance the content of soil organic matter, which has a wide range of application value for improving clay, sandy soil and poor soil.

Description

Technical Field

[0001] The invention relates to the technical field of compound fertilizers, and in particular to a soil structure-improving and fertilizing compound fertilizer, and a preparation method and application thereof. Background Art

[0002] Throughout the history of agricultural production, the use of fertilizers has always been a key factor in increasing crop yields. From the initial farmyard manure to the later chemical single-element fertilizers, and then to the emergence of compound fertilizers, it reflects the continuous improvement of agricultural requirements for fertilizer quality and function. With the increase in population and demand for agricultural products, the scale of agricultural production has continued to expand, and the demand for fertilizers has become increasingly diversified. Compound fertilizers have gradually become one of the main types of fertilizers in modern agricultural production because they can provide multiple nutrients at the same time, reduce the number of fertilizations and labor costs. For a long time, unreasonable agricultural production methods, such as excessive use of chemical fertilizers, unreasonable irrigation and tillage, have led to a series of soil problems. The organic matter content of soil in many areas has decreased and the soil structure has been destroyed, especially for special soil types such as clay, rare earth and poor soil. Clay has poor air permeability and water permeability, which affects the growth of plant roots; rare earth requires targeted nutrient supply and soil improvement measures due to its special physical and chemical properties; poor soil lacks sufficient nutrients and good soil structure to support plant growth. These soil problems not only limit the improvement of crop yield and quality, but also pose a threat to the sustainable development of agriculture.

[0003] Existing compound fertilizers usually contain major nutrient elements such as nitrogen, phosphorus, and potassium. Some compound fertilizers also add trace elements to meet the needs of crops for multiple nutrients during growth. The comprehensiveness of this nutrient helps to ensure the normal growth and development of crops and reduce the phenomenon of poor growth caused by the lack of a single nutrient. The use of compound fertilizers can reduce the number of fertilizations and the workload. Compared with the application of single fertilizers separately, compound fertilizers can provide multiple nutrients in one fertilization, which can save a lot of manpower, material resources and time for large-scale agricultural production. Modern compound fertilizer production technology can adjust the proportion of nutrients according to the needs of different crops and soils. For example, for fruit crops with high potassium requirements, high-potassium compound fertilizers can be produced; for leafy vegetables, high-nitrogen compound fertilizers can be produced. The adjustability of this nutrient ratio enables compound fertilizers to better adapt to different agricultural production scenarios and improve the pertinence and effectiveness of fertilizers. Most traditional compound fertilizers focus on providing nutrients to crops, while ignoring the improvement of soil structure. Long-term use of these compound fertilizers may cause soil compaction, especially when large amounts of chemical fertilizers are used. For example, some compound fertilizers containing a large amount of ammonium nitrogen will acidify the soil after nitrification in the soil, destroy the soil aggregate structure, reduce the soil's air permeability and water permeability, and thus affect the growth of plant roots and the activity of soil microorganisms. The chemical components in some compound fertilizers may have a negative impact on soil microorganisms. After some high-concentration chemical fertilizers are applied to the soil, they will change the physical and chemical properties of the soil, such as pH value, osmotic pressure, etc., which is not conducive to the survival and reproduction of soil microorganisms. For special soil types such as clay, rare earth and poor soil, the improvement effect of traditional compound fertilizers is poor. In clay, compound fertilizers may not be able to effectively improve its air permeability and water permeability; in rare earth, due to its special elemental composition and soil properties, ordinary compound fertilizers cannot well meet the needs of rare earth plants for specific nutrients; poor soil lacks sufficient organic matter and microorganisms, and traditional compound fertilizers are difficult to fundamentally improve its barren condition and cannot effectively improve the soil's fertilizer and water retention capacity and nutrient supply capacity.

[0004] In summary, the development of compound fertilizer has gone through a process from simple nutrient supply to comprehensive soil improvement and ecological function enhancement. Although the existing compound fertilizer technology has certain advantages in nutrient supply and fertilization efficiency, it has obvious deficiencies in improving soil structure, protecting soil microorganisms and improving special soils. Therefore, it is of great practical significance to develop a compound fertilizer that can improve soil structure, increase soil microbial activity and content, and enhance soil organic matter content. Summary of the invention

[0005] Purpose of the invention:

[0006] The invention aims to provide a soil structure-improving and fertilizing compound fertilizer, which can improve soil structure, enhance soil microbial activity and content, and enhance soil organic matter content.

[0007] The technical solution of the present invention:

[0008] The invention provides a soil structure improving and fertilizing compound fertilizer. The raw materials for preparing the soil structure improving and fertilizing compound fertilizer include: modified polymer, livestock and poultry feces fermentation product, compound bacillus fermentation product, compound inorganic fertilizer and organic plant residue.

[0009] Furthermore, the raw materials for preparing the soil structure improving and fertilizing compound fertilizer include, by weight: 5-10 parts of modified polymer, 30-45 parts of livestock and poultry manure fermentation products, 2-5 parts of compound Bacillus fermentation products, 25-35 parts of compound inorganic fertilizers, and 15-25 parts of organic plant residues.

[0010] Furthermore, the preparation of the modified polymer comprises the following steps:

[0011] S1: Under a nitrogen atmosphere, add 2-hydroxyethyl acrylate and 4-methylstyrene into a three-necked flask, then add toluene and stir to completely dissolve;

[0012] S2: placing the three-necked flask in step S1 in a constant temperature water bath, heating it to 60-80° C., then adding azobisisobutyronitrile dissolved in toluene to start a polymerization reaction, and stirring the reaction continuously for 4-6 hours;

[0013] S3: After the reaction in step S2 is completed, the reactants are filtered, extracted, and dried to obtain a hydrophilic polymer.

[0014] S4: Add the hydrophilic polymer obtained in step S3 into a three-necked flask, add an appropriate amount of dimethylformamide, and stir to dissolve;

[0015] S5: under stirring, slowly add dodecyl trimethyl ammonium phosphate to the three-necked flask in step S4, then dropwise add sodium hydroxide solution, adjust the pH value of the reaction system to 9-10, raise the reaction temperature to 40-60° C., and then stir for 2-4 hours;

[0016] S6: After the reaction in step S5 is completed, ethylene oxide and boron trifluoride ether complex are slowly added into the three-necked flask, and the reaction is continued for 2-4 hours;

[0017] S7: After the reaction in step S6 is completed, the reaction mixture is slowly poured into hexane for precipitation to precipitate the polymer, and the precipitate is collected by filtration, then washed with deionized water, and then dried to obtain the hydrophilic polymer containing the quaternary ammonium salt and the active group.

[0018] Furthermore, the composite bacillus fermentation product is prepared by fermenting bacillus, microorganisms and a solid matrix.

[0019] Furthermore, the solid matrix is ​​bran and soybean meal.

[0020] Furthermore, the preparation of the composite Bacillus fermentation product comprises the following steps:

[0021] SS1: Weigh bran and soybean meal in proportion, mix well, add appropriate amount of water, then add inorganic salt, stir well, and put into a solid culture plate with a thickness of 3-5cm;

[0022] SS2: After mixing Bacillus and microorganisms in proportion, spray them evenly on the surface of the solid culture plate in step SS1, and then put the solid culture plate into a fermentation box with a temperature of 30-40°C and a humidity of 85-90%. Ferment for 6-12 hours, and turn the box over every 2-4 hours;

[0023] SS3: After the fermentation is completed, the solid fermentation product is dried and crushed to obtain the composite Bacillus fermentation product.

[0024] Furthermore, the Bacillus is a mixture of one or more of Bacillus subtilis, Bacillus halodurans, and Bacillus gelatinosa.

[0025] Furthermore, the microorganisms are a mixture of one or more of nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria.

[0026] Furthermore, the mass ratio of the Bacillus to the microorganism is 1:1-1.25.

[0027] Furthermore, the total mass of the bacillus and the microorganisms is 10-20% of the mass of the solid matrix.

[0028] Furthermore, the compound inorganic fertilizer is a mixture of one or more of urea, superphosphate and potassium chloride.

[0029] Furthermore, the organic plant residue is a mixture of one or more of rapeseed cake, cottonseed cake and soybean cake.

[0030] The present invention also provides a method for preparing a soil structure-improving and fertilizing compound fertilizer, which is characterized by comprising the following steps:

[0031] Step 1: Add the modified polymer, livestock and poultry manure fermentation product, compound Bacillus fermentation product, compound inorganic fertilizer, and organic plant residue into a mixer according to a certain proportion, start the mixer, and control the stirring speed and time to fully mix the raw materials;

[0032] Step 2: using a granulator to granulate, conveying the material in step 1 to the extruder of the granulator, extruding granules through a die, and controlling the size of the granulated particles;

[0033] Step 3: subjecting the granulated particles to low-temperature drying equipment to obtain the soil structure-improving and fertilizing compound fertilizer.

[0034] Furthermore, in step 1, the stirring speed is 20-30 r / min, the stirring time is 30-60 min, the particle size in step 2 is 2-5 mm, and the low-temperature drying temperature in step 3 is 30-40° C.

[0035] The application of the soil structure improving and fertilizing compound fertilizer of the present invention is characterized in that the soil structure improving and fertilizing compound fertilizer can be applied to clay, sandy soil and poor soil.

[0036] Beneficial effects:

[0037] The soil structure improving and fertilizing compound fertilizer of the present invention can make soil particles stick together, increase soil porosity, improve soil air permeability and water permeability, improve soil pore structure, enable soil to better retain moisture, and the modified polymer can interact with organic components such as humus in the soil to increase soil organic matter content; the composite bacillus fermentation product is obtained through process fermentation, the activity and quantity of microorganisms are improved, and the synergistic effect between different bacillus strains is promoted, so that the decomposition and conversion efficiency of insoluble phosphorus and potassium in the soil is higher, and more abundant absorbable nutrients can be provided for plants, and the growth and development of plants can be promoted; the soil structure improving and fertilizing compound fertilizer of the present invention can also improve clay, sandy soil and poor soil, and has wide application value. DETAILED DESCRIPTION

[0038] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0039] Boron trifluoride ether complex was purchased from Beijing Xinao Xunchi Chemical Co., Ltd.; dodecyl trimethylammonium phosphate, CAS No. 51572-94-2, was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; 2-hydroxyethyl acrylate was purchased from Shandong Xuchen Chemical Technology Co., Ltd.; 4-methylstyrene was purchased from Shanghai Myril Biochemical Technology Co., Ltd.; livestock and poultry manure fermentation product was purchased from Henan Daoxi Environmental Engineering Co., Ltd.; Bacillus subtilis was purchased from Jinan Qiyue Chemical Technology Co., Ltd.; Bacillus gelatinous was purchased from Jinan Herui Biotechnology Co., Ltd.; nitrogen-fixing bacteria, potassium-solubilizing bacteria, and phosphate-solubilizing bacteria were purchased from Hebi Baihui Biotechnology Co., Ltd.

[0040] Unless otherwise specified, the chemical reagents used in the present invention are all commercially available analytically pure.

[0041] Preparation of modified polymers:

[0042] S1: Under a nitrogen atmosphere, add 20 g of 2-hydroxyethyl acrylate and 10 g of 4-methylstyrene into a three-necked flask, then add 1 L of toluene and stir to completely dissolve;

[0043] S2: Place the three-necked flask in step S1 in a constant temperature water bath, raise the temperature to 65°C, then add 0.3 g of azobisisobutyronitrile dissolved in 10 mL of toluene to start the polymerization reaction, and continue stirring for 4 hours;

[0044] S3: After the reaction in step S2 is completed, the reactants are filtered, extracted, and dried to obtain a hydrophilic polymer;

[0045] S4: Add 10 g of the hydrophilic polymer obtained in step S3 into a three-necked flask, add 500 mL of dimethylformamide, and stir evenly;

[0046] S5: Under stirring, slowly add 5 g of dodecyl trimethyl ammonium phosphate to the three-necked flask in step S4, then dropwise add 1 mol / L sodium hydroxide solution to adjust the pH value of the reaction system to 9, heat the reaction to 50° C., and then stir for 2 hours;

[0047] S6: After the reaction in step S5 is completed, 5 g of ethylene oxide and 0.2 g of boron trifluoride ether complex are slowly added into the three-necked flask, and the reaction is continued for 3 hours;

[0048] S7: After the reaction is completed, the reaction mixture is slowly poured into hexane for precipitation to precipitate the polymer. The precipitate is collected by filtration, then washed with deionized water, and then dried at 50° C. for 24 hours to obtain the modified polymer.

[0049] Preparation of complex Bacillus fermentation product A:

[0050] SS1: Weigh 3.5kg bran and 1.5kg soybean meal in proportion, mix well, add 5L water, then add 10g magnesium sulfate and 15g potassium dihydrogen phosphate, stir well, and put into a solid culture plate with a thickness of 3cm;

[0051] SS2: 0.5 kg of Bacillus subtilis and 0.5 kg of nitrogen-fixing bacteria were mixed and sprayed evenly on the surface of the solid culture plate in step SS1, and then the solid culture plate was placed in a fermentation box with a temperature of 37° C. and a humidity of 88%. The fermentation was carried out for 12 hours, and the culture plate was turned over every 2 hours.

[0052] SS3: After the fermentation in step SS2 is completed, the solid fermentation product is dried and crushed to obtain the composite Bacillus fermentation product.

[0053] Preparation of complex Bacillus fermentation product B:

[0054] The present preparation is different from the composite Bacillus fermentation product A in that 0.5 kg of Bacillus subtilis and 0.5 kg of nitrogen-fixing bacteria in step SS2 are replaced with 0.25 kg of Bacillus subtilis, 0.25 kg of Bacillus gelatinus, 0.15 kg of nitrogen-fixing bacteria, 0.25 kg of potassium-solubilizing bacteria, and 0.1 kg of phosphate-solubilizing bacteria.

[0055] Preparation of complex Bacillus fermentation product C:

[0056] The present preparation is different from the composite Bacillus fermentation product A in that 0.5 kg of Bacillus subtilis and 0.5 kg of nitrogen-fixing bacteria in step SS2 are replaced by 0.2 kg of Bacillus subtilis and 0.25 kg of nitrogen-fixing bacteria.

[0057] Preparation of complex Bacillus fermentation product D:

[0058] The difference between the present preparation and the composite Bacillus fermentation product A is that 0.5 kg of Bacillus subtilis and 0.5 kg of nitrogen-fixing bacteria in step SS2 are replaced by 0.4 kg of Bacillus subtilis and 0.6 kg of nitrogen-fixing bacteria.

[0059] Preparation of complex Bacillus fermentation product E:

[0060] The difference between the present preparation and the composite Bacillus fermentation product A is that 0.5 kg of Bacillus subtilis and 0.5 kg of nitrogen-fixing bacteria in step SS2 are replaced by 1 kg of Bacillus subtilis.

[0061] The method for preparing a soil structure-improving and fertilizing compound fertilizer comprises the following steps:

[0062] Step 1: Add the modified polymer, livestock and poultry manure fermentation product, compound Bacillus fermentation product, compound inorganic fertilizer, and organic plant residue into a mixer according to a certain proportion, turn on the mixer, stir at a speed of 20r / min, and stir for 60min to fully mix the raw materials;

[0063] Step 2: Granulate the material in step 1 by using a granulator, convey the material to the extruder of the granulator, extrude the granules through a die, and the granulated granules have a size of 2 mm;

[0064] Step 3: low-temperature drying the granulated particles at a temperature of 30° C. to obtain the soil structure-improving and fertilizing compound fertilizer.

[0065] Examples 1 to 6

[0066] The compound fertilizer for improving soil structure and increasing fertility was prepared according to the above-mentioned method for preparing the compound fertilizer for improving soil structure and increasing fertility. Table 1 is the ingredient list of the compound fertilizer for improving soil structure and increasing fertility of Examples 1 to 6.

[0067] Table 1: Ingredients of the soil structure improving and fertilizing compound fertilizer of Examples 1 to 6

[0068]

[0069] Comparative Example 1:

[0070] The difference between this preparation and Example 2 is that in step 1, no modified polymer is added to the mixer.

[0071] Comparative Example 2:

[0072] The present preparation is different from Example 2 in that 5 parts by weight of the complex Bacillus fermentation product in step 1 is replaced by 2.5 parts by weight of Bacillus subtilis and 2.5 parts by weight of nitrogen-fixing bacteria.

[0073] Performance test experiment: 10 kg of clay sample was collected, and after natural drying, it was passed through a 200-mesh sieve for later use. Several equal amounts (500 g each) of the sieved soil samples were taken, and 1% by weight of the soil sample was added to the soil sample. The soil structure-improving and fertilizing compound fertilizers prepared in Examples 1-6 and Comparative Examples 1-2 were added respectively. After stirring evenly, the soil sample was placed in a sealed bag and allowed to stand at room temperature for 36 hours to allow the compound fertilizer to fully react with the soil, and then the following experiment was carried out.

[0074] 1. Soil pore structure test: The soil after adding compound fertilizer was tested by soil porosity meter (BEST porosity analyzer, BEST Instrument Technology (Beijing) Co., Ltd.) to measure the total porosity of the soil to evaluate the changes in soil pore structure. 2. Soil organic matter content increase experiment: Analyze the changes in organic matter content in the soil after adding compound fertilizer. The potassium dichromate oxidation-external heating method was used to determine the soil organic matter content. For each soil sample in the blank control group and the polymer addition group, accurately weigh 0.1-0.5g (accurate to 0.0001g) of soil sample and put it into a dry hard glass test tube. Add 5.00mL of potassium dichromate standard solution to each test tube, then slowly add 5mL of concentrated sulfuric acid, and insert a A small funnel is used to prevent the solution from splashing out during heating. The test tube is placed in an oil bath and heated at 170-180°C for 5 minutes. After heating, the test tube is taken out and cooled to room temperature. The solution in the test tube is transferred to a 250mL conical flask. The test tube is rinsed with a small amount of distilled water, and the washing liquid is poured into the conical flask to make the total volume about 60-70mL. 3-4 drops of o-phenanthroline indicator are added to the conical flask, and the solution is titrated with ferrous sulfate solution until the color of the solution changes from orange-yellow to blue-green, and finally to brick red as the end point. Record the amount of ferrous sulfate solution (V). At the same time, a blank test is performed, that is, no soil sample is added, and the other steps are the same. Record the amount of ferrous sulfate solution (V) in the blank test. The soil organic matter content was calculated according to the formula: organic matter content (g / kg) = [C×(VV)×0.003×1.724×1.1] / m×1000, where C is the concentration of ferrous sulfate solution (mol / L), V is the amount of ferrous sulfate solution used in the blank test (mL), V is the amount of ferrous sulfate solution used in the sample determination (mL), 0.003 is the millimolar mass of 1 / 4 carbon atom (g / mmol), 1.724 is the oxidation correction coefficient, 1.1 is a coefficient set to compensate for possible losses during the digestion process, and m is the mass of the soil sample (g).

[0075] 3. Microbial quantity detection experiment: The plate counting method was used to detect microorganisms in the clay soils of Examples 1-6 and Comparative Examples 1-2, respectively, and the colony forming units (CFU) on the plates were counted to determine the number of microorganisms.

[0076] The test results are shown in Table 3.

[0077] Table 3: Performance test results

[0078]

[0079]

[0080] As can be seen from Table 3, the soil structure improving and fertilizing compound fertilizer of the present invention can increase the porosity of the soil, improve the air permeability and water permeability of the soil, improve the pore structure of the soil, enable the soil to better retain moisture, increase the soil organic matter content, and increase the number of soil microorganisms. Specifically, from Example 4 and Example 1, it can be seen that when preparing the composite bacillus fermentation product, the unreasonable ratio of the total mass of bacillus and microorganisms to the mass of the solid matrix will lead to the prepared soil structure improving and fertilizing compound fertilizer for improving the content of soil organic matter and the number of microorganisms. The expected effect cannot be achieved; from Example 5 and Example 1, it can be seen that when preparing the composite bacillus fermentation product, the unreasonable ratio of the mass of bacillus and microorganisms will lead to the prepared soil structure improving and fertilizing compound fertilizer for improving the content of soil organic matter and the number of microorganisms. The ability to decrease, the expected effect cannot be achieved; from Example 6 and Example 1, By comparison with Example 1, it can be seen that when preparing the composite bacillus fermentation product, the unreasonable mass ratio of bacillus to microorganisms will lead to the prepared soil structure improving fertilization type compound fertilizer for improving soil organic matter content and microorganism quantity decreased ability, and the expected effect cannot be achieved; from Comparative Example 1 and Example 1, it can be seen that when preparing the soil structure improving fertilization type compound fertilizer, no modified polymer is added, which will lead to the preparation of the soil structure improving fertilization type compound fertilizer for improving soil pore structure, soil air permeability and water permeability deteriorating, and the ability to improve soil organic matter content and microorganism quantity decreased, and the expected effect cannot be achieved; from Comparative Example 2 and Example 1, it can be seen that when preparing the soil structure improving fertilization type compound fertilizer, no composite bacillus fermentation product is added, and the direct addition of bacillus and microorganisms will weaken the ability of the prepared soil structure improving fertilization type compound fertilizer to improve soil organic matter content and increase microbial quantity, and the expected effect cannot be achieved.

[0081] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A soil structure-improving and fertilizing compound fertilizer, characterized in that: The raw materials for preparing the soil structure improving and fertilizing compound fertilizer include: modified polymer, livestock and poultry feces fermentation product, compound bacillus fermentation product, compound inorganic fertilizer and organic plant residue.

2. The soil structure improving and fertilizing compound fertilizer according to claim 1, characterized in that: The raw materials for preparing the soil structure improving and fertilizing compound fertilizer include, by weight: 5-10 parts of modified polymer, 30-45 parts of livestock and poultry feces fermentation, 2-5 parts of compound Bacillus fermentation, 25-35 parts of compound inorganic fertilizer, and 15-25 parts of organic plant residue.

3. The soil structure improving and fertilizing compound fertilizer according to claim 1, characterized in that: The preparation of the modified polymer comprises the following steps: S1: Under a nitrogen atmosphere, add 2-hydroxyethyl acrylate and 4-methylstyrene into a three-necked flask, then add toluene and stir to completely dissolve; S2: placing the three-necked flask in step S1 in a constant temperature water bath, heating it to 60-80° C., then adding azobisisobutyronitrile dissolved in toluene to start a polymerization reaction, and stirring the reaction continuously for 4-6 hours; S3: After the reaction in step S2 is completed, the reactants are filtered, extracted, and dried to obtain a hydrophilic polymer; S4: Add the hydrophilic polymer prepared in S3 into a three-necked flask, add an appropriate amount of dimethylformamide, and stir to dissolve; S5: under stirring, slowly add dodecyl trimethyl ammonium phosphate to the three-necked flask in step S4, then dropwise add sodium hydroxide solution, adjust the pH value of the reaction system to 9-10, raise the reaction temperature to 40-60° C., and then stir for 2-4 hours; S6: After the reaction in step S5 is completed, ethylene oxide and boron trifluoride ether complex are slowly added into the three-necked flask, and the reaction is continued for 2-4 hours; S7: After the reaction in step S6 is completed, the reaction mixture is slowly poured into hexane for precipitation to precipitate the polymer, and the precipitate is collected by filtration, then washed with deionized water, and then dried to obtain the hydrophilic polymer containing the quaternary ammonium salt and the active group.

4. The soil structure improving and fertilizing compound fertilizer according to claim 3, characterized in that: The composite bacillus fermentation product is prepared by fermenting bacillus, microorganisms and a solid matrix through a process; the solid matrix is ​​bran and soybean meal.

5. The soil structure improving and fertilizing compound fertilizer according to claim 3, characterized in that: The preparation of the composite bacillus fermentation product comprises the following steps: SS1: Weigh bran and soybean meal in proportion, mix well, add appropriate amount of water, then add inorganic salt, stir well, and put into a solid culture plate with a thickness of 3-5cm; SS2: After mixing Bacillus and microorganisms in proportion, spray them evenly on the surface of the solid culture plate in step SS1, and then put the solid culture plate into a fermentation box with a temperature of 30-40°C and a humidity of 85-90%. Ferment for 6-12 hours, and turn the box over every 2-4 hours; SS3: After the fermentation in step SS2 is completed, the solid fermentation product is dried and crushed to obtain the composite Bacillus fermentation product.

6. The soil structure improving and fertilizing compound fertilizer according to claim 4, characterized in that: The Bacillus is a mixture of one or more of Bacillus subtilis, Bacillus halodurans, and Bacillus gelatinosa; and the microorganisms are a mixture of one or more of nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria.

7. The soil structure improving and fertilizing compound fertilizer according to claim 4, characterized in that: The mass ratio of the bacillus to the microorganism is 1:1-1.25; the total mass of the bacillus and the microorganism is 10-20% of the mass of the solid matrix.

8. The method for preparing the soil structure-improving and fertilizing compound fertilizer according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Add the modified polymer, livestock and poultry manure fermentation product, compound Bacillus fermentation product, compound inorganic fertilizer, and organic plant residue into a mixer according to a certain proportion, start the mixer, and control the stirring speed and time to fully mix the raw materials; Step 2: using a granulator to granulate, conveying the material in step 1 to the extruder of the granulator, extruding granules through a die, and controlling the size of the granulated particles; Step 3: subjecting the granulated particles to low-temperature drying equipment to obtain the soil structure-improving and fertilizing compound fertilizer.

9. The method for preparing the soil structure-improving and fertilizing compound fertilizer according to claim 8, characterized in that: The stirring speed of step 1 is 20-30r / min, the stirring time is 30-60min, the particle size of step 2 is 2-5mm; and the low-temperature drying temperature of step 3 is 30-40°C.

10. The use of the compound fertilizer for improving soil structure and increasing fertility according to any one of claims 1 to 7, characterized in that: The soil structure-improving and fertilizing compound fertilizer can be applied to clay, sandy soil and poor soil.

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