Microbial-based soil amendment composite fertilizer and method of making same

Abstract

The present application relates to the technical field of bio-organic fertilizer, in particular to a kind of microbial base soil improvement compound fertilizer and its preparation method;For solving the problems of existing fertilizer single fertilizer efficiency, soil improvement effect is not obvious and cannot provide nutrients for a long time;The compound fertilizer is added with five kinds of microorganism bacteria, bacillus subtilis can play the role of phosphorus and potassium, bacillus megaterium can produce organic acid, promote the absorption of nutrient elements, bacillus licheniformis can effectively inhibit the reproduction of harmful pathogenic bacteria, trichoderma can enhance plant salt tolerance, repair soil salinization, clover rhizobium has nitrogen fixation ability, utilizes sodium alginate-trehalose-humic acid composite microcapsule semi-permeable membrane structure, and synthesizes crosslinked sodium lignosulfonate modified polyurethane coated urea, realizes long-acting nutrient supply, promotes soil fertility circulation, improves crop yield, also makes soil digestion capacity enhance, further improves the overall soil fertility.

Description

Technical Field

[0001] This invention relates to the field of bio-organic fertilizer technology, and in particular to a microbial-based soil-improving compound fertilizer and its preparation method. Background Technology

[0002] Soil is the foundation of plant growth, but with increased agricultural activity and changing environmental conditions, soil quality faces numerous challenges, such as degradation, acidification, and salinization. These problems significantly impact crop yield and quality. To overcome these issues, various soil improvement technologies have been explored. However, traditional fertilizers have some drawbacks in practical applications, such as limited soil improvement effects, single-effect fertilizer use, and inability to provide nutrients over a long period. Therefore, this invention provides a microbial-based soil-improving compound fertilizer and its preparation method, which not only solves the problems of traditional methods but also holds promise for achieving sustainable agricultural development. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a microbial-based soil-improving compound fertilizer and its preparation method, thereby solving the problems of existing fertilizers having limited fertilization effects, insignificant soil improvement effects, and inability to provide nutrients over a long period.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a microbial-based soil amendment compound fertilizer, comprising the following parts by weight: The composition consists of 40-80 parts of biochar composite microbial microcapsules, 25-50 parts of urea coated with cross-linked sodium lignosulfonate modified polyurethane, 20-40 parts of dried chicken manure, 10-20 parts of monoammonium phosphate, 7-14 parts of potassium sulfate, 1-2 parts of zinc sulfate monohydrate, 0.8-1.6 parts of sodium borate, and 10-20 parts of white clay. The biochar-composite microbial microcapsules are prepared by the following steps: Step A1: Inoculate Bacillus subtilis powder onto nutrient agar medium and incubate at 35°C for 24 hours. Add sterile water to a sterile conical flask, shake for 10 minutes, and incubate in a constant temperature shaker at 150 rpm until OD reaches the target value. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate Bacillus megaterium powder onto nutrient agar medium and incubate at 35°C for 24 hours. Add sterile water to a sterile conical flask, shake for 10 minutes, and incubate in a constant temperature shaker at 150 rpm until OD reaches the target value. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate Bacillus licheniformis powder onto nutrient agar medium and incubate at 35°C for 24 hours. Add sterile water to a sterile conical flask, shake for 10 minutes, and incubate in a constant temperature shaker at 150 rpm until OD reaches the target value. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate Trichoderma on PDA medium for activation, incubate at 28°C for 5 days, agitate the mycelia and spores on the surface of the medium with sterile water, inoculate into PD medium, and incubate at 28°C until OD. 600 =0.8, yielding bacterial suspension 4; Step A5: Add the clover rhizobium powder and sterile water to a sterilized conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28°C for 5-7 days. Wash off the colonies with sterile water, transfer them to YMA liquid medium, and incubate at 28°C and 180 rpm until OD reaches the target value. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve the weathered coal, add it to a single-necked flask equipped with a stirrer along with sodium hydroxide solution, stir for 24 hours, centrifuge and collect the supernatant, adjust the pH to 1 with hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution, wash 3-5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, add it to a sterilized conical flask along with sodium alginate, trehalose, and deionized water, stir, add biochar powder, autoclave, and suspend the bacteria. Mixing liquid 1, bacterial suspension 2, bacterial suspension 3, bacterial suspension 4, and bacterial suspension 5 into a sterile conical flask, stirring under aseptic conditions, and injecting into a sterile syringe, then sterilizing the calcium chloride solution at 121℃ for 20 minutes by moist heat, adding it dropwise from 4 cm above the surface of the calcium chloride solution using a sterile syringe, and placing it in a refrigerator to solidify for 2 hours, washing 2-4 times with sterile water, blotting the surface moisture with sterile filter paper, and drying it in an oven at 40℃ to obtain biochar composite microbial microcapsules.

[0005] In a preferred embodiment of the present invention, the ratio of Bacillus subtilis powder to sterile water in step A1 is 0.1-0.2g:10-20mL.

[0006] In a preferred embodiment of the present invention, the ratio of Bacillus megaterium powder to sterile water in step A2 is 0.1-0.2g:10-20mL.

[0007] In a preferred embodiment of the present invention, the ratio of Bacillus licheniformis powder to sterile water in step A3 is 0.1-0.2g:10-20mL.

[0008] In a preferred embodiment of the present invention, the ratio of Trichoderma and sterile water used in step A4 is 0.04-0.08g:4-8mL.

[0009] In a preferred embodiment of the present invention, the ratio of clover rhizobium powder to sterile water in step A5 is 0.1-0.2g:10-20mL.

[0010] In a preferred embodiment of the present invention, the ratio of the amounts of weathered coal, sodium hydroxide solution, sodium alginate, trehalose, deionized water, biochar powder, bacterial suspension 1, bacterial suspension 2, bacterial suspension 3, bacterial suspension 4, bacterial suspension 5, and calcium chloride solution in step A7 is 0.64-1.28g: 2.56-5.12mL: 1.28-2.56g: 0.64-1.28g: 64-128mL: 0.5-1g: 6-12mL: 6-12mL: 6-12mL: 4-8mL: 4-8mL: 200-400mL.

[0011] In a preferred embodiment of the present invention, the sodium hydroxide solution in step A7 has a mass fraction of 25%.

[0012] In a preferred embodiment of the present invention, the molar concentration of hydrochloric acid in step A7 is 1 mol / L.

[0013] In a preferred embodiment of the present invention, the molar concentration of the hydrofluoric acid solution in step A7 is 1 mol / L.

[0014] In a preferred embodiment of the present invention, the volume ratio of hydrochloric acid to hydrofluoric acid in the hydrochloric acid / hydrofluoric acid solution in step A7 is 1:1.

[0015] In a preferred embodiment of the present invention, the calcium chloride solution in step A7 has a mass-volume percentage of 2%.

[0016] In a preferred embodiment of the present invention, the cross-linked sodium lignosulfonate modified polyurethane-coated urea is prepared by the following steps: Step B1: Add sodium lignosulfonate and deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 5-10 min, adjust the pH to 12 with sodium hydroxide solution, transfer to an oil bath, add ethylene glycol diglycidyl ether at 90℃ and stir for 3 h, add to ice water, adjust the pH to 3 with hydrochloric acid solution, let stand for 5 h, vacuum filter, wash the filter residue 3-5 times with distilled water, dry and grind through a 200-mesh sieve, add polytetrahydrofuran, isophorone diisocyanate and N,N-dimethylformamide to a two-necked flask equipped with a stirrer, stir for 10-20 min, add urea and let stand for 2 h, place in a petri dish to solidify, and obtain cross-linked sodium lignosulfonate modified polyurethane coated urea.

[0017] In a preferred embodiment of the present invention, the ratio of sodium lignosulfonate, deionized water, ethylene glycol diglycidyl ether, polytetrahydrofuran, isophorone diisocyanate, N,N-dimethylformamide, and urea in step B1 is 7.5-15g: 25-50mL: 0.157-0.314mmol: 10-20g: 4-8g: 70-140mL: 15-30g.

[0018] In a preferred embodiment of the present invention, the molar concentration of the sodium hydroxide solution in step B1 is 1 mol / L.

[0019] In a preferred embodiment of the present invention, the molar concentration of the hydrochloric acid solution in step B1 is 1 mol / L.

[0020] In a preferred embodiment of the present invention, the polytetrahydrofuran mentioned in step B1 is of the type PTMG-1000.

[0021] On the other hand, the present invention provides a method for preparing a microbial-based soil-amoring compound fertilizer, which specifically includes the following steps: Step 1: Weigh out 40-80 parts of biochar composite microbial microcapsules, 25-50 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 20-40 parts of dried chicken manure, 10-20 parts of monoammonium phosphate, 7-14 parts of potassium sulfate, 1-2 parts of zinc sulfate monohydrate, 0.8-1.6 parts of sodium borate, and 10-20 parts of white clay according to the following weight proportions, and set aside. Step 2: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 15-20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step 3: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

[0022] The beneficial effects of this invention are: The microbial-based soil-improving compound fertilizer and its preparation method of the present invention, by adding five kinds of microorganisms to the compound fertilizer, utilizes the microcapsule structure to release nutrients available to crops, helps to prolong the supply time of nutrients, promotes the absorption of plant roots, and can promote changes in the soil environment, which is conducive to the growth of more beneficial microorganisms. It synthesizes cross-linked sodium lignin sulfonate and modifies the surface of urea with polyurethane to prolong the nitrogen release cycle and improve the slow-release performance of nutrients, thus playing a significant role in soil improvement.

[0023] To prepare a microbial-based soil-improving compound fertilizer, firstly, bacterial suspensions were prepared from Bacillus subtilis powder, Bacillus megaterium powder, Bacillus licheniformis powder, Trichoderma, and Rhizobium trifoliatum powder, respectively. These suspensions were then formulated into a compound bacterial solution. The compound bacterial solution was then combined with biochar via a sodium alginate-trehalose-humic acid process to create biochar-composite microcapsules. The biochar, with its rich mesoporous structure, improves soil aggregate structure and enhances water and fertilizer retention capacity. Bacillus subtilis can solubilize phosphorus and potassium, promote the decomposition of organic matter into humus, and improve soil structure. Bacillus megaterium can produce organic acids, promoting nutrient absorption and improving fertilizer efficiency. It can also solubilize phosphorus and potassium. Bacillus licheniformis can effectively inhibit the reproduction of harmful pathogens. Trichoderma can enhance plant salt tolerance, repair soil salinization, and reduce soil pH and alkalinity. Clover rhizobium has nitrogen-fixing capabilities, converting free nitrogen from the air into plant-usable combined nitrogen. Humic acid contains abundant organic matter with various active groups such as carboxyl, hydroxyl, and phenolic hydroxyl groups, exhibiting strong cation exchange capacity, adsorption and dispersion capacity, and acid-base buffering properties. This technology can improve soil cation exchange capacity, enhance the adsorption and slow release of nutrients such as ammonium nitrogen, potassium, and calcium, and reduce nutrient leaching. Sodium alginate-trehalose-humic acid composite microcapsules can form a semi-permeable membrane structure, controlling the release rate of organic nutrients such as humic acid and trehalose, preventing rapid nutrient loss and achieving long-term fertilization. Simultaneously, it protects microorganisms from environmental stresses such as ultraviolet radiation, high temperature, dryness, and chemical disinfectants, extending their survival time and activity in the soil. Sodium lignosulfonate undergoes an epoxy group ring-opening reaction with ethylene glycol diglycidyl ether to obtain… Cross-linked sodium lignin sulfonate is produced by reacting the hydroxyl groups in sodium lignin sulfonate and polytetrahydrofuran with the isocyanate groups in isophorone diisocyanate, and then coating the surface of urea to obtain sodium lignin sulfonate modified polyurethane-coated urea. The hydrophobic aromatic ring network of sodium lignin sulfonate and the hard segment shell of polyurethane form a dual diffusion barrier, prolonging the release cycle and improving nitrogen utilization. This compound fertilizer can provide both immediate and long-term nutrient support, reduce environmental pollution, improve soil structure and fertility, and increase crop yield and quality. Detailed Implementation

[0024] The technical solution of the present invention will be further described in a non-limiting manner below with reference to specific embodiments.

[0025] Example 1: The preparation method of the microbial-based soil amendment compound fertilizer in this embodiment includes the following steps: Step A1: Inoculate 0.1g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 10mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.1g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 10mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.1g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 10mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.04g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 4mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.1g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 5 days. Wash off the colonies with 10mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [value missing]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 0.64g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 2.56mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 3-5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, add 1.28g sodium alginate, 0.64g trehalose and 64mL deionized water. Add 0.5g of biochar powder to a sterile conical flask, stir, and autoclave. Mix 6mL of bacterial suspension 1, 6mL of bacterial suspension 2, 6mL of bacterial suspension 3, 4mL of bacterial suspension 4, and 4mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under aseptic conditions and inject into a sterile syringe. Sterilize 200mL of 2% (w / v) calcium chloride solution at 121℃ for 20min using a wet heat. Add the solution dropwise from 4cm above the surface of the calcium chloride solution using a sterile syringe. Place in a refrigerator to solidify for 2h. Wash 2-4 times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40℃ to obtain biochar composite microbial microcapsules. Step A8: Add 7.5g sodium lignosulfonate and 25mL deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 5min, adjust the pH to 12 with 1mol / L sodium hydroxide solution, transfer to an oil bath, add 0.157mmol ethylene glycol diglycidyl ether at 90℃ and stir for 3h, add to ice water, adjust the pH to 3 with 1mol / L hydrochloric acid solution, let stand for 5h, vacuum filter, wash the filter residue 3 times with distilled water, dry and grind through a 200-mesh sieve, add 10g PTMG-1000 polytetrahydrofuran, 4g isophorone diisocyanate and 70mL N,N-dimethylformamide to a two-necked flask equipped with a stirrer, stir for 10min, add 15g urea and let stand for 2h, place in a petri dish to solidify, and obtain cross-linked sodium lignosulfonate modified polyurethane coated urea; Step A9: Weigh out 40 parts of biochar composite microbial microcapsules, 25 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 20 parts of dried chicken manure, 10 parts of monoammonium phosphate, 7 parts of potassium sulfate, 1 part of zinc sulfate monohydrate, 0.8 parts of sodium borate, and 10 parts of white clay according to the following weight proportions, and set aside. Step A10: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 15%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A11: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

[0026] Example 2: The preparation method of the microbial-based soil amendment compound fertilizer in this embodiment includes the following steps: Step A1: Inoculate 0.15g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 15mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.15g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 15mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.15g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 15mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.06g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 6mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.15g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 6 days. Wash off the colonies with 5mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [value missing]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 0.96g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 3.84mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 4 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, add it to 1.92g sodium alginate, 0.96g trehalose and 96mL deionized water. Add 0.75g of biochar powder to a sterile conical flask, stir, and autoclave. Mix 9mL of bacterial suspension 1, 9mL of bacterial suspension 2, 9mL of bacterial suspension 3, 6mL of bacterial suspension 4, and 6mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under aseptic conditions and inject into a sterile syringe. Sterilize 300mL of 2% (w / v) calcium chloride solution at 121℃ for 20min using a wet heat. Add the solution dropwise from 4cm above the surface of the calcium chloride solution using a sterile syringe. Place in a refrigerator to solidify for 2h. Wash three times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40℃ to obtain biochar composite microbial microcapsules. Step A8: Add 11.25g sodium lignosulfonate and 37.5mL deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 7min, adjust the pH to 12 with 1mol / L sodium hydroxide solution, transfer to an oil bath, add 0.2355mmol ethylene glycol diglycidyl ether at 90℃ and stir for 3h, add to ice water, adjust the pH to 3 with 1mol / L hydrochloric acid solution, let stand for 5h, vacuum filter, wash the filter residue 4 times with distilled water, dry and grind through a 200-mesh sieve, add 15g PTMG-1000 polytetrahydrofuran, 6g isophorone diisocyanate and 105mL N,N-dimethylformamide to a two-necked flask equipped with a stirrer, stir for 15min, add 22.5g urea and let stand for 2h, place in a petri dish to solidify, and obtain cross-linked sodium lignosulfonate modified polyurethane coated urea; Step A9: Weigh out 60 parts of biochar composite microbial microcapsules, 37.5 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 30 parts of dried chicken manure, 15 parts of monoammonium phosphate, 10.5 parts of potassium sulfate, 1.5 parts of zinc sulfate monohydrate, 1.2 parts of sodium borate, and 15 parts of white clay according to the following weight proportions, and set aside. Step A10: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 17.5%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A11: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

[0027] Example 3: The preparation method of the microbial-based soil amendment compound fertilizer in this embodiment includes the following steps: Step A1: Inoculate 0.2g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.2g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.2g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.08g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 8mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.2g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 7 days. Wash off the colonies with 20mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [missing value]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 1.28g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 5.12mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, add it to 2.56g sodium alginate, 1.28g trehalose and 128mL deionized water. Add 1g of biochar powder to a sterile conical flask, stir, and autoclave. Mix 12mL of bacterial suspension 1, 12mL of bacterial suspension 2, 12mL of bacterial suspension 3, 8mL of bacterial suspension 4, and 8mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under sterile conditions and inject into a sterile syringe. Sterilize 400mL of 2% (w / v) calcium chloride solution at 121℃ for 20min using a sterile syringe. Add the solution dropwise from 4cm above the surface of the calcium chloride solution using a sterile syringe. Place in a refrigerator to solidify for 2h. Wash 4 times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40℃ to obtain biochar composite microbial microcapsules. Step A8: Add 15g sodium lignosulfonate and 50mL deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 10min, adjust the pH to 12 with 1mol / L sodium hydroxide solution, transfer to an oil bath, add 0.314mmol ethylene glycol diglycidyl ether at 90℃ and stir for 3h, add to ice water, adjust the pH to 3 with 1mol / L hydrochloric acid solution, let stand for 5h, vacuum filter, wash the filter residue 5 times with distilled water, dry and grind through a 200-mesh sieve, add 20g PTMG-1000 polytetrahydrofuran, 8g isophorone diisocyanate and 140mL N,N-dimethylformamide to a two-necked flask equipped with a stirrer, stir for 20min, add 30g urea and let stand for 2h, place in a petri dish to solidify, and obtain cross-linked sodium lignosulfonate modified polyurethane coated urea; Step A9: Weigh out 80 parts of biochar composite microbial microcapsules, 50 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 40 parts of dried chicken manure, 20 parts of monoammonium phosphate, 14 parts of potassium sulfate, 2 parts of zinc sulfate monohydrate, 1.6 parts of sodium borate, and 20 parts of white clay according to the following weight proportions, and set aside. Step A10: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A11: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

[0028] Comparative Example 1: The preparation method of the microbial-based soil amendment compound fertilizer in this comparative example includes the following steps: Step A1: Inoculate 0.2g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.2g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.2g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.08g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 8mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.2g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 7 days. Wash off the colonies with 20mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [missing value]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 1.28g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 5.12mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, add it to 2.56g sodium alginate, 1.28g trehalose and 128mL deionized water. Add 1g of biochar powder to a sterile conical flask, stir, and autoclave. Mix 12mL of bacterial suspension 1, 12mL of bacterial suspension 2, 12mL of bacterial suspension 3, 8mL of bacterial suspension 4, and 8mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under sterile conditions and inject into a sterile syringe. Sterilize 400mL of 2% (w / v) calcium chloride solution at 121℃ for 20min using a sterile syringe. Add the solution dropwise from 4cm above the surface of the calcium chloride solution using a sterile syringe. Place in a refrigerator to solidify for 2h. Wash 4 times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40℃ to obtain biochar composite microbial microcapsules. Step A8: Weigh out 80 parts by weight of biochar compound microbial microcapsules, 50 parts by weight of urea, 40 parts by weight of dried chicken manure, 20 parts by weight of monoammonium phosphate, 14 parts by weight of potassium sulfate, 2 parts by weight of zinc sulfate monohydrate, 1.6 parts by weight of sodium borate and 20 parts by weight of white clay, and set aside. Step A9: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly, air dry until the moisture content is 20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A10: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

[0029] Comparative Example 2: The preparation method of the microbial-based soil amendment compound fertilizer in this comparative example includes the following steps: Step A1: Inoculate 0.2g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.2g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing].600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.2g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.08g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 8mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.2g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 7 days. Wash off the colonies with 20mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [missing value]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 1.28g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 5.12mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, and mix with 2.56g sodium alginate, 1.28g trehalose, and 128mL of sodium hydroxide solution. Add L of deionized water to a sterile conical flask, stir, and autoclave. Mix 12 mL of bacterial suspension 1, 12 mL of bacterial suspension 2, 12 mL of bacterial suspension 3, 8 mL of bacterial suspension 4, and 8 mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under aseptic conditions and inject into a sterile syringe. Sterilize 400 mL of 2% (w / v) calcium chloride solution at 121°C for 20 min using a wet heat. Add the solution dropwise using a sterile syringe from 4 cm above the surface of the calcium chloride solution. Place in a refrigerator to solidify for 2 h. Wash 4 times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40°C to obtain composite microbial microcapsules. Step A8: Add 15g sodium lignosulfonate and 50mL deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 10min, adjust the pH to 12 with 1mol / L sodium hydroxide solution, transfer to an oil bath, add 0.314mmol ethylene glycol diglycidyl ether at 90℃ and stir for 3h, add to ice water, adjust the pH to 3 with 1mol / L hydrochloric acid solution, let stand for 5h, vacuum filter, wash the filter residue 5 times with distilled water, dry and grind through a 200-mesh sieve, add 20g PTMG-1000 polytetrahydrofuran, 8g isophorone diisocyanate and 140mL N,N-dimethylformamide to a two-necked flask equipped with a stirrer, stir for 20min, add 30g urea and let stand for 2h, place in a petri dish to solidify, and obtain cross-linked sodium lignosulfonate modified polyurethane coated urea; Step A9: Weigh out 80 parts of compound microbial microcapsules, 50 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 40 parts of dried chicken manure, 20 parts of monoammonium phosphate, 14 parts of potassium sulfate, 2 parts of zinc sulfate monohydrate, 1.6 parts of sodium borate, and 20 parts of white clay according to the following weight proportions, and set aside. Step A10: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A11: Mix the fertilizer matrix with the compound microbial microcapsules at a ratio of 1:4 to obtain a microbial-based soil amendment compound fertilizer.

[0030] Comparative Example 3: The preparation method of the microbial-based soil amendment compound fertilizer in this comparative example includes the following steps: Step A1: Inoculate 0.2g of Bacillus subtilis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 1; Step A2: Inoculate 0.2g of Bacillus megaterium powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing]. 600 =0.8, resulting in bacterial suspension 2; Step A3: Inoculate 0.2g of Bacillus licheniformis powder onto nutrient agar medium and incubate at 35℃ for 24h. Add 20mL of sterile water to a sterile Erlenmeyer flask, shake for 10min, and incubate in a constant temperature shaker at 150r / min until OD reaches [value missing].600 =0.8, yielding bacterial suspension 3; Step A4: Inoculate 0.08g of Trichoderma on PDA medium for activation, and incubate at 28℃ for 5 days. Use 8mL of sterile water to agitate the mycelia and spores on the surface of the medium, then inoculate into PD medium and incubate at 28℃ until OD (Occurrence Limit) is reached. 600 =0.8, yielding bacterial suspension 4; Step A5: Add 0.2g of *Rhizobium trifoliatum* powder and sterile water to a sterile conical flask, shake for 10 minutes to prepare a suspension, spread it evenly on YMA solid medium, and incubate at 28℃ for 7 days. Wash off the colonies with 20mL of sterile water, transfer them to YMA liquid medium, and incubate at 28℃ and 180r / min until OD reaches [missing value]. 600 =0.8, yielding 5 bacterial suspensions; Step A6: After washing the wheat straw with water, place it in a drying oven and dry it at 130°C. Crush it, place it in a crucible, transfer it to a muffle furnace and carbonize it at 300°C for 3 hours. Cool it to room temperature, carbonize it at 500°C for 1 hour, cool it to room temperature, grind it, and pass it through a 200-mesh sieve to obtain biochar powder. Step A7: Grind and sieve 1.28g of weathered coal, add it to a single-necked flask equipped with a stirrer along with 5.12mL of 25% sodium hydroxide solution, stir for 24h, centrifuge and collect the supernatant, adjust the pH to 1 with 1mol / L hydrochloric acid, let stand, centrifuge to remove the supernatant, wash the precipitate 3 times with hydrochloric acid / hydrofluoric acid solution (volume ratio of hydrochloric acid to hydrofluoric acid is 1:1, molar concentration of hydrochloric acid is 1mol / L, molar concentration of hydrofluoric acid solution is 1mol / L), wash 5 times with pure water, freeze dry, pulverize and pass through a 200-mesh sieve, and mix with 2.56g sodium alginate, 1.28g trehalose, and 128mL of sodium hydroxide solution. Add L of deionized water to a sterile conical flask, stir, and autoclave. Mix 12 mL of bacterial suspension 1, 12 mL of bacterial suspension 2, 12 mL of bacterial suspension 3, 8 mL of bacterial suspension 4, and 8 mL of bacterial suspension 5 and add them to the sterile conical flask. Stir under aseptic conditions and inject into a sterile syringe. Sterilize 400 mL of 2% (w / v) calcium chloride solution at 121°C for 20 min using a wet heat. Add the solution dropwise using a sterile syringe from 4 cm above the surface of the calcium chloride solution. Place in a refrigerator to solidify for 2 h. Wash 4 times with sterile water, blot dry with sterile filter paper, and dry in an oven at 40°C to obtain composite microbial microcapsules. Step A8: Weigh out 80 parts of compound microbial microcapsules, 50 parts of urea, 40 parts of dried chicken manure, 20 parts of monoammonium phosphate, 14 parts of potassium sulfate, 2 parts of zinc sulfate monohydrate, 1.6 parts of sodium borate, and 20 parts of white clay according to the weight ratio, and set aside. Step A9: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly, air dry until the moisture content is 20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step A10: Mix the fertilizer matrix with the compound microbial microcapsules at a ratio of 1:4 to obtain a microbial-based soil amendment compound fertilizer.

[0031] Performance testing: The soil type tested in the experimental field was yellow-brown soil, with a pH value of 7.78, a total nitrogen content of 0.795 g / kg, an available phosphorus content of 25.811 g / kg, an available potassium content of 0.663 mg / kg, and a topsoil organic matter content of 10.69 g / kg. The experiment began in early spring and ended in early winter of the same year. A randomized block design was used to determine the effects of the compound fertilizers in Examples 1-3 and Comparative Examples 1-3 on soil indices. Each sample group was replicated three times, with a total of five experimental areas. Each area was 3m × 5m. Corn was sown using the hill-sowing method, with plant spacing of 25cm and row spacing of 30cm. Each area had 10 rows with 20 plants per row. Before sowing, corn seeds were treated with microbial fertilizer and placed in a shaded, cool place for 1 hour (to ensure full contact between the microorganisms and the seeds). Sowing was then carried out. Irrigation conditions varied depending on the phenological stage of the corn's growth period, with irrigation based on a seedling stage of 900m... 3 / hm 2 1100m during the jointing stage 3 / hm 2 Flowering period 1250m 3 / hm 2 Grouting period 750m 3 / hm 2 ; During the maize maturity period, taking into account factors such as drainage conditions, slope aspect, and human disturbance in the experimental area, five sampling points were randomly selected from each region, totaling 15 regions. Each sample group was replicated three times. 200g of rhizosphere soil samples were collected from a depth of 10-30cm using conventional methods, placed in sterile sampling bags, sealed sequentially, and labeled with the sampling location, depth, date, and collector. Depending on the experimental purpose, the soil samples were sieved with sieves of 2-4mm diameter and promptly air-dried. To preserve the original soil properties, avoid or delay soil degradation, maintain the activity of soil microorganisms, and inhibit their metabolism, the samples were stored at 4℃. Soil total nitrogen was determined using the Kjeldahl distillation method. The content of available phosphorus in soil was determined by sodium bicarbonate extraction-molybdenum antimony colorimetric method; Determination of available potassium content in soil by flame atomic absorption spectrophotometry; Determination of soil organic matter content using potassium dichromate-sulfuric acid heating method.

[0032] First, 10g of samples from Examples 1-3 and Comparative Examples 1-3 were placed in a mesh bag, then the bag was placed in a transparent glass bottle, 200mL of distilled water was added, the bottle was sealed, and the bottle was placed in an incubator at 25°C. The nitrogen concentration was measured every 24 hours. After sampling, another 200mL of distilled water was added to the glass bottle and sealed. The bottle was then incubated at 25°C. The nutrient release rate of the solution was measured using an RX-5000α refractometer to obtain the cumulative N release rate on day 1, day 14, and day 90.

[0033] Table 1. Total nitrogen content, available phosphorus content, available potassium content, and organic matter content of Examples 1-3 and Comparative Examples 1-3 Table 2. Cumulative N release rates on days 1, 14, and 90 of Examples 1-3 and Comparative Examples 1-3 Referring to the table above, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the compound fertilizer prepared by mixing biochar composite microbial microcapsules with cross-linked sodium lignosulfonate modified polyurethane-coated urea fertilizer matrix has a good soil improvement effect. Based on the comparison between Example 3 and Comparative Example 1, it can be seen that the total nitrogen content of the compound fertilizer made by mixing biochar composite microbial microcapsules with cross-linked sodium lignosulfonate modified polyurethane-coated urea fertilizer matrix is ​​greater than that of the compound fertilizer made by mixing biochar composite microbial microcapsules with urea fertilizer matrix. This indicates that the compound fertilizer made by mixing biochar composite microbial microcapsules with cross-linked sodium lignosulfonate modified polyurethane-coated urea fertilizer matrix has excellent soil improvement effect. Based on the comparison between Example 3 and Comparative Example 2, it can be seen that the total nitrogen content of the compound fertilizer made by mixing biochar-based microbial microcapsules with cross-linked sodium lignosulfonate-modified polyurethane-coated urea fertilizer matrix is ​​greater than that of the compound fertilizer made by mixing biochar-based microbial microcapsules with cross-linked sodium lignosulfonate-modified polyurethane-coated urea fertilizer matrix. This indicates that the compound fertilizer made by mixing biochar-based microbial microcapsules with cross-linked sodium lignosulfonate-modified polyurethane-coated urea fertilizer matrix has excellent soil improvement effects. Based on the comparison between Example 3 and Comparative Example 3, it can be seen that the total nitrogen content of the compound fertilizer prepared by mixing biochar-based microbial microcapsules with cross-linked sodium lignosulfonate-modified polyurethane-coated urea fertilizer matrix is ​​greater than that of the compound fertilizer prepared by mixing biochar-based microbial microcapsules with urea fertilizer matrix. This indicates that the compound fertilizer prepared by mixing biochar-based microbial microcapsules with cross-linked sodium lignosulfonate-modified polyurethane-coated urea fertilizer matrix has excellent soil improvement effects.

[0034] The foregoing description illustrates and describes preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, and any modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A microbial-based soil amendment compound fertilizer, characterized in that, Includes the following components by weight: The composition consists of 40-80 parts of biochar composite microbial microcapsules, 25-50 parts of urea coated with cross-linked sodium lignosulfonate modified polyurethane, 20-40 parts of dried chicken manure, 10-20 parts of monoammonium phosphate, 7-14 parts of potassium sulfate, 1-2 parts of zinc sulfate monohydrate, 0.8-1.6 parts of sodium borate, and 10-20 parts of white clay. The biochar-composite microbial microcapsules are prepared by the following steps: Step A1: Culture Bacillus subtilis powder, shake with sterile water, and culture to obtain bacterial suspension 1; Step A2: Culture Bacillus megaterium powder, shake with sterile water, and culture to obtain bacterial suspension 2; Step A3: Culture the Bacillus licheniformis powder, shake it with sterile water, and culture it to obtain bacterial suspension 3; Step A4: Cultivate Trichoderma, agitate with sterile water, and continue culturing to obtain a fungal suspension 4; Step A5: Shake the clover rhizobium powder with sterile water and culture to obtain bacterial suspension 5; Step A6: Dry, crush, carbonize, grind and sieve the wheat straw to obtain biochar powder; Step A7: Grind and sieve the weathered coal, stir with sodium hydroxide solution, wash and dry, pulverize and sieve again, add sodium alginate, trehalose and deionized water to a sterilized conical flask and stir, add biochar powder and sterilize, mix bacterial suspension 1, bacterial suspension 2, bacterial suspension 3, bacterial suspension 4 and bacterial suspension 5 and add to a sterilized conical flask and stir, inject into a sterile syringe, sterilize with calcium chloride solution, add dropwise with a sterile syringe 4 cm away from the surface of calcium chloride solution, solidify, wash and dry to obtain biochar composite microbial microcapsules.

2. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of Bacillus subtilis powder to sterile water in step A1 is 0.1-0.2g:10-20mL.

3. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of Bacillus megaterium powder to sterile water in step A2 is 0.1-0.2g:10-20mL.

4. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of Bacillus licheniformis powder to sterile water in step A3 is 0.1-0.2g:10-20mL.

5. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of Trichoderma to sterile water in step A4 is 0.04-0.08g: 4-8mL.

6. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of clover rhizobium powder to sterile water in step A5 is 0.1-0.2g:10-20mL.

7. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The ratio of weathered coal, sodium hydroxide solution, sodium alginate, trehalose, deionized water, biochar powder, bacterial suspension 1, bacterial suspension 2, bacterial suspension 3, bacterial suspension 4, bacterial suspension 5, and calcium chloride solution used in step A7 is 0.64-1.28g : 2.56-5.12mL : 1.28-2.56g : 0.64-1.28g : 64-128mL : 0.5-1g : 6-12mL : 6-12mL : 6-12mL : 4-8mL : 4-8mL : 200-400mL.

8. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The sodium hydroxide solution in step A7 has a mass fraction of 25%; the calcium chloride solution in step A7 has a mass volume percentage of 2%.

9. The microbial-based soil amendment compound fertilizer according to claim 1, characterized in that, The cross-linked sodium lignin sulfonate modified polyurethane-coated urea is prepared by the following steps: Sodium lignosulfonate and deionized water were stirred, ethylene glycol diglycidyl ether was added and stirred to react, dried, ground and sieved, and then mixed with polytetrahydrofuran, isophorone diisocyanate and N,N-dimethylformamide for 1 hour. Urea was added and allowed to stand and solidify to obtain cross-linked sodium lignosulfonate modified polyurethane coated urea. The ratio of sodium lignosulfonate, deionized water, ethylene glycol diglycidyl ether, polytetrahydrofuran, isophorone diisocyanate, N,N-dimethylformamide, and urea is 7.5g:25mL:0.157mmol:10g:4g:70mL:15g; the polytetrahydrofuran is of type PTMG-1000.

10. A method for preparing a microbial-based soil-amoring compound fertilizer, characterized in that, The preparation of the microbial-based soil amendment compound fertilizer as described in any one of claims 1-9 includes the following steps: Step 1: Weigh out 40-80 parts of biochar composite microbial microcapsules, 25-50 parts of cross-linked sodium lignosulfonate modified polyurethane-coated urea, 20-40 parts of dried chicken manure, 10-20 parts of monoammonium phosphate, 7-14 parts of potassium sulfate, 1-2 parts of zinc sulfate monohydrate, 0.8-1.6 parts of sodium borate, and 10-20 parts of white clay according to the following weight proportions, and set aside. Step 2: Mix urea, dried chicken manure, monoammonium phosphate, potassium sulfate, zinc sulfate monohydrate, sodium borate, and white clay evenly with cross-linked sodium lignosulfonate modified polyurethane, air dry until the moisture content is 15-20%, crush and sieve, granulate using a disc granulator, and sieve through an 18-mesh screen to obtain the fertilizer matrix. Step 3: Mix the fertilizer matrix with biochar-based microbial microcapsules at a ratio of 1:4 to obtain microbial-based soil amendment compound fertilizer.

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