A microbial fertilizer with high humic content and its preparation method

Abstract

This invention discloses a high-humicity microbial fertilizer and its preparation method, belonging to the field of microbial fertilizer technology. The method involves adding a mixed carrier, a protective agent, and fermentation broth to a stirred tank in a specific ratio, followed by shaking and adsorption, filtration, and drying with forced air until the moisture content of the absorbent resin powder reaches 30-35%. The powder is then continuously granulated using a granulator and sieved to obtain microbial agent granules with a particle size of 2-5 mm. The microbial agent granules and sodium humate are mixed at a mass ratio of 1-2:10 to obtain the high-humicity microbial fertilizer. The aggregated short fibers, under the adhesive and physical entanglement effects of the protective agent, increase the internal space of the microbial agent granules while improving structural stability, providing a stable growth and reproduction environment for microorganisms, and improving the long-term storage of the fertilizer and the survival rate of microorganisms after application. The enlarged microbial agent granules provide support, increasing soil looseness and providing a good respiratory environment for crop roots.

Description

Technical Field

[0001] This invention belongs to the field of microbial fertilizer technology, specifically relating to a high-humicity microbial fertilizer and its preparation method. Background Technology

[0002] Microbial fertilizers, simply put, are "microorganisms + fertilizer." They are a type of fertilizer containing live microorganisms, fundamentally different from conventional chemical fertilizers because their main component is beneficial microorganisms, not mineral elements. Based on the type of microorganism, they can be divided into bacterial fertilizers, actinomycete fertilizers, fungal fertilizers, algae fertilizers, and compound microbial fertilizers.

[0003] In recent years, the extensive use of chemical fertilizers has accelerated the rate of soil imbalance, affecting normal land cultivation. Saline-alkali soils generally have high pH values, low organic matter content, and low permeability, severely impacting crop growth. To protect the ecological environment of arable land, and with the deepening research into microbial fertilizers, their application in agricultural production has become quite widespread. For example, rhizobium fertilizer is one of the earliest researched and applied microbial fertilizers; it can form root nodules with leguminous plants, fixing atmospheric nitrogen and providing nitrogen nutrition for the plants. Other types of microbial fertilizers, such as nitrogen-fixing bacteria fertilizers, phosphorus-solubilizing bacteria fertilizers, and potassium-solubilizing bacteria fertilizers, are also gradually being applied.

[0004] However, after the application of microbial fertilizers, the survival rate of microorganisms in the inoculants is not high due to the influence of the soil environment in saline-alkali land, resulting in a decrease in the yield-increasing effect of microbial fertilizers. Summary of the Invention

[0005] One objective of this invention is to provide a microbial fertilizer with high humic content, which solves the problem of low viable bacteria retention rate after application of microbial fertilizer by providing a stable environment for microbial growth and reproduction; another objective is to provide a method for preparing a microbial fertilizer with high humic content.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A microbial fertilizer with high humic content is prepared through the following steps:

[0008] Step 1: Inoculate the activated microbial strains into the sterilized culture medium and culture them in a fermenter at a stirring speed of 150-180 r / min and a temperature of 30±0.5℃ for 10-12 h. During the culture, adjust the pH value to 6.5-6.8 with ammonia water to obtain the fermentation broth.

[0009] Step 2: Add the mixed carrier, protectant and fermentation broth to the stirred tank at a ratio of 0.5-1g:0.5-1g:10mL. Shake and adsorb at a stirring speed of 150-180r / min and 30±0.5℃ for 12-16h. Filter and dry with forced air until the water content of the water-absorbing resin powder is 30-35%. Continuously granulate using a granulator, sieve, and obtain bacterial agent granules with a particle size of 2-5mm.

[0010] Step 3: Mix the microbial agent granules and sodium humate at a mass ratio of 1-2:10 to obtain a microbial fertilizer with high humic content.

[0011] Furthermore, the microbial strain consists of *Bacillus aryabhattai*, *Bacillus velezensis*, and *Priscilla*. Specifically, *Bacillus aryabhattai* was deposited on March 9, 2022, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC NO. 24486. *Bacillus velezensis* was deposited in 2023... On July 7, 2023, this strain of *Priestiasp.* was deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC NO. 27827.

[0012] Furthermore, the viable count of Bacillus argentis in the fermentation broth was >1.5 × 10⁻⁶. 10 CFU / mL, viable count of Bacillus belyssus > 1.5 × 10⁻⁶ 10 CFU / mL, Priestella viable count > 1.2 × 10⁻⁶ 10 CFU / mL.

[0013] Furthermore, the protective agent is a mixture of fish protein and trehalose in a mass ratio of 1:0.5-1.

[0014] Furthermore, the mixed support is prepared through the following steps:

[0015] Step 1: Add desulfurized gypsum powder and 8-10 times the mass of anhydrous ethanol to a mixing tank and stir to form a suspension. Then add 1.5-2 times the mass of desulfurized gypsum powder and silane coupling agent KH550 and stir at 200-500 r / min for 4-6 h. Centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder.

[0016] Step 2: Add modified gypsum powder, cellulose, and deionized water to a reaction vessel. Stir for 40-60 minutes under nitrogen protection and at 85-95℃ to gelatinize the cellulose and mix it evenly with the modified gypsum powder. Then cool to 55-65℃, add potassium persulfate as an initiator to the reaction vessel and stir for 5-10 minutes. Then add methacrylic acid, methacrylamide, and crosslinking agent to the reaction vessel and stir for 100-120 minutes. Collect the gel product and wash it 3-5 times with deionized water. Dry, pulverize, and pass through a 60-80 mesh sieve to obtain water-absorbing resin powder.

[0017] Step 3: Add isophorone diisocyanate, polytetrahydrofuran, and polylactic acid to the reactor. Stir for 20-30 minutes at 60-70℃ and 150-200 r / min. Then add dibutyltin dilaurate as a catalyst to the reactor. Heat to 80-85℃ under nitrogen protection and stir for 2-2.5 hours. Next, add N,N-dimethylformamide and 1,4-butanediol to the reactor and stir for 2-2.5 hours. Filter the mixture, wash 2-3 times with deionized water, dry, and pulverize to obtain biodegradable polymer particles. Use melt spinning to prepare fibers with a length of 10-20 mm from the biodegradable polymer particles. Then soak them in a hydrogen peroxide solution with a mass concentration of 10-12 g / L for 6-8 hours, filter, and dry to obtain biodegradable short fibers.

[0018] Step 4: Mix the water-absorbing resin powder and biodegradable short fibers in an airflow at a mass ratio of 1:4-5 to obtain a mixed carrier.

[0019] Furthermore, the ratio of modified gypsum powder, cellulose, deionized water, potassium persulfate, methacrylic acid, methacrylamide and crosslinking agent is 1-1.2g: 1.5-1.6g: 80-100mL: 0.25g: 8-10g: 5-6g: 0.05g.

[0020] Furthermore, the crosslinking agent is N,N'-methylenebisacrylamide or N-(hydroxymethyl)acrylamide.

[0021] Furthermore, the ratio of isophorone diisocyanate, polytetrahydrofuran, polylactic acid, dibutyltin dilaurate, N,N-dimethylformamide and 1,4-butanediol is 4.4-4.6g:10g:0.6-0.8g:0.03g:15-16g:1-1.2g.

[0022] The beneficial effects of this invention are:

[0023] This invention relates to a microbial fertilizer prepared by blending microbial agent granules with sodium humate. Sodium humate, as a soil conditioner, helps improve the soil environment in saline-alkali land, reducing soil salinity and pH, and enhancing soil fertility. The mixed carrier is prepared by mixing water-absorbing resin powder and biodegradable short fibers. The combination of these two components increases the adsorption effect on the fermentation broth. After granulation, the water-absorbing resin powder expands the aggregated biodegradable short fibers upon absorbing water. The aggregated short fibers, under the binding and physical entanglement effects of the protective agent, increase the internal space of the microbial agent granules while improving structural stability. This provides a stable growth and reproduction environment for microorganisms, improving the long-term storage of the fertilizer and the survival rate of microorganisms after application. The microbial strains consist of *Bacillus aspergillus*, *Bacillus belye*, and *Priscilla*. Through their individual and synergistic effects, they improve the plant's utilization of soil nutrients, inhibit the growth and reproduction of pathogens, and improve soil structure. The enlarged microbial agent granules also provide support, maintaining and increasing soil looseness, providing a good respiratory environment for crop roots, and contributing to increased crop yield.

[0024] Desulfurized gypsum powder is added during the preparation of water-absorbing resin powder. The soluble calcium ions in the desulfurized gypsum powder can displace sodium ions in saline-alkali soil, helping to lower the soil pH and improve the saline-alkali land. After modification with a silane coupling agent, the desulfurized gypsum powder has increased dispersibility, which helps to improve the water absorption ratio of the water-absorbing resin, further enhancing its improvement effect on saline-alkali land. Cellulose, after gelatinization, improves its water absorption performance. Adding it to the preparation of water-absorbing resin helps to improve the water retention performance of the resin and reduces its production cost.

[0025] The biodegradable short fibers, treated with hydrogen peroxide solution, increase their surface roughness, enhancing their adsorption capacity for the fermentation broth and improving their friction with the water-absorbing resin powder, thus facilitating the granulation of the microbial agent. The protectant contains fish protein and trehalose, which increase the viscosity of the fermentation broth, aiding in the granulation of the microbial agent. Fish protein provides various nutrients such as organic matter, nitrogen, phosphorus, and potassium, which are crucial for crop growth. Fish protein also promotes the reproduction of microorganisms, which activate soil nutrients, improve soil water and fertilizer retention capacity, and help to aggregate compacted soil, thereby benefiting crop growth and development. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a microbial fertilizer with high humic content, including the following implementation steps:

[0029] Step 1: The microbial strain consisted of *Bacillus aspergillus*, *Bacillus belye*, and *Priscilla*. The activated microbial strain was inoculated into a sterilized culture medium containing 30 g / L glucose, 25 g / L beef extract, 10 g / L peptone, and 3.2 g / L magnesium sulfate. The culture was carried out in a fermenter at 150 rpm and 30 ± 0.5 °C for 10 hours. During the culture, the pH was adjusted to 6.5 with ammonia water, yielding 1000 L of fermentation broth. The viable count of *Bacillus aspergillus* in the fermentation broth was >1.5 × 10⁻⁶. 10 CFU / mL, viable count of Bacillus belyssus > 1.5 × 10⁻⁶ 10 CFU / mL, Priestella viable count > 1.2 × 10⁻⁶ 10 CFU / mL.

[0030] Step 2: Add desulfurized gypsum powder and 8 times its mass of anhydrous ethanol to a stirred tank and stir to form a suspension. Then add 1.5 times its mass of silane coupling agent KH550 to the desulfurized gypsum powder and stir at 200 r / min for 4-6 h. Centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder. Add 10 kg of modified gypsum powder, 15 kg of cellulose, and 800 L of deionized water to a reaction vessel and stir at 85 °C for 40 min under nitrogen protection to gelatinize the cellulose and mix it evenly with the modified gypsum powder. Then cool to 55 °C, add 2.5 kg of potassium persulfate as an initiator to the reaction vessel and stir for 5 min. Then add 80 kg of methacrylic acid, 50 kg of methacrylamide, and 0.5 kg of N,N'-methylenebisacrylamide as a crosslinking agent to the reaction vessel and stir for 100 min. Collect the gel product and wash it with deionized water 3-5 times, dry it, pulverize it, and pass it through a 60 mesh sieve to obtain water-absorbing resin powder.

[0031] Step 3: Add 44 kg of isophorone diisocyanate, 100 kg of polytetrahydrofuran, and 6-8 kg of polylactic acid to the reactor. Stir for 20 min at 60℃ and 150 r / min. Then add 0.3 kg of dibutyltin dilaurate as a catalyst to the reactor. Heat to 80℃ under nitrogen protection and stir for 2 h. Then add 150 kg of N,N-dimethylformamide and 10 kg of 1,4-butanediol to the reactor. Stir for 2 h and filter out the material. Wash twice with deionized water, dry, and pulverize to obtain biodegradable polymer particles. Use melt spinning to prepare fibers with a length of 10 mm from the biodegradable polymer particles. Then soak them in a 10 g / L hydrogen peroxide solution for 6 h, filter, and dry to obtain biodegradable short fibers.

[0032] Step 4: Mix 10 kg of water-absorbing resin powder and 40 kg of biodegradable short fibers in an airflow at a mass ratio of 1:4 to obtain a mixed carrier; mix 10 kg of fish protein and 5 kg of trehalose to prepare a protective agent; add 5 kg of the mixed carrier, 5 kg of the protective agent and 100 L of fermentation broth to a stirred tank, and shake and adsorb for 12 h at a stirring speed of 150 r / min and a temperature of 30 ± 0.5℃; filter; dry with forced air until the moisture content of the water-absorbing resin powder is 30%; granulate continuously using a granulator; sieve to obtain bacterial agent particles with a particle size of 2 mm.

[0033] Step 5: Mix 10kg of microbial agent granules and 100kg of sodium humate to obtain a microbial fertilizer with high humic content.

[0034] Example 2

[0035] This embodiment provides a microbial fertilizer with high humic content, including the following implementation steps:

[0036] Step 1: The microbial strain consists of *Bacillus aspergillus*, *Bacillus belye*, and *Priscilla*. The activated microbial strain is inoculated into a sterilized culture medium containing 30 g / L glucose, 25 g / L beef extract, 10 g / L peptone, and 3.2 g / L magnesium sulfate. Using a fermenter, the mixture is incubated at 160 rpm and 30 ± 0.5℃ for 10-12 hours. During incubation, the pH is adjusted to 6.6 with ammonia water, yielding 1000 L of fermentation broth. The viable count of *Bacillus aspergillus* in the fermentation broth is >1.5 × 10⁻⁶. 10 CFU / mL, viable count of Bacillus belyssus > 1.5 × 10⁻⁶ 10 CFU / mL, Priestella viable count > 1.2 × 10⁻⁶ 10 CFU / mL.

[0037] Step 2: Add desulfurized gypsum powder and 9 times its mass of anhydrous ethanol to a stirred tank and stir to form a suspension. Then add 1.8 times its mass of silane coupling agent KH550 to the desulfurized gypsum powder and stir at 350 r / min for 5 h. Centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder. Add 11 kg of modified gypsum powder, 15.5 kg of cellulose, and 900 L of deionized water to a reaction vessel and stir for 50 min under nitrogen protection and at 90 °C to gelatinize the cellulose and mix it evenly with the modified gypsum powder. Then cool to 50 °C, add 2.5 kg of potassium persulfate as an initiator to the reaction vessel and stir for 8 min. Then add 90 kg of methacrylic acid, 55 kg of methacrylamide, and 0.5 kg of N,N'-methylenebisacrylamide as a crosslinking agent to the reaction vessel and stir for 110 min. Collect the gel product and wash it 4 times with deionized water, dry it, pulverize it, and pass it through a 70 mesh sieve to obtain water-absorbing resin powder.

[0038] Step 3: Add 45 kg of isophorone diisocyanate, 100 kg of polytetrahydrofuran, and 7 kg of polylactic acid to the reactor. Stir for 25 min at 65℃ and 180 r / min. Then add 0.3 kg of dibutyltin dilaurate as a catalyst to the reactor. Heat to 82℃ under nitrogen protection and stir for 2.2 h. Then add 155 kg of N,N-dimethylformamide and 11 kg of 1,4-butanediol to the reactor. Stir for 2.2 h and filter out the material. Wash twice with deionized water, dry, and pulverize to obtain biodegradable polymer particles. Use melt spinning to prepare fibers with a length of 15 mm from the biodegradable polymer particles. Then soak them in a hydrogen peroxide solution with a mass concentration of 11 g / L for 7 h, filter, and dry to obtain biodegradable short fibers.

[0039] Step 4: Mix 10 kg of water-absorbing resin powder and 45 kg of biodegradable short fibers in an airflow at a mass ratio of 1:4.5 to obtain a mixed carrier; mix 10 kg of fish protein and 8 kg of trehalose to prepare a protective agent; add 8 kg of the mixed carrier, 8 kg of the protective agent and 100 L of fermentation broth to a stirred tank, and shake and adsorb for 14 h at a stirring speed of 160 r / min and a temperature of 30 ± 0.5℃; filter; dry with forced air until the moisture content of the water-absorbing resin powder is 32%; granulate continuously using a granulator; sieve to obtain bacterial agent granules with a particle size of 3 mm.

[0040] Step 5: Mix 15kg of microbial agent granules and 100kg of sodium humate to obtain a microbial fertilizer with high humic content.

[0041] Example 3

[0042] This embodiment provides a microbial fertilizer with high humic content, including the following implementation steps:

[0043] Step 1: The microbial strain consisted of *Bacillus aspergillus*, *Bacillus belye*, and *Priscilla*. The activated microbial strain was inoculated into a sterilized culture medium containing 30 g / L glucose, 25 g / L beef extract, 10 g / L peptone, and 3.2 g / L magnesium sulfate. The culture was carried out in a fermenter at 170 rpm and 30 ± 0.5 °C for 11 hours. During the culture, the pH was adjusted to 6.6 with ammonia water, yielding 1000 L of fermentation broth. The viable count of *Bacillus aspergillus* in the fermentation broth was >1.5 × 10⁻⁶. 10 CFU / mL, viable count of Bacillus belyssus > 1.5 × 10⁻⁶ 10 CFU / mL, Priestella viable count > 1.2 × 10⁻⁶ 10 CFU / mL.

[0044] Step 2: Add desulfurized gypsum powder and 9 times its mass of anhydrous ethanol to a stirred tank and stir to form a suspension. Then add 1.8 times its mass of silane coupling agent KH550 to the desulfurized gypsum powder and stir at 350 r / min for 5 h. Centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder. Add 11 kg of modified gypsum powder, 15.5 kg of cellulose, and 900 L of deionized water to a reaction vessel and stir at 90 °C for 50 min under nitrogen protection to gelatinize the cellulose and mix it evenly with the modified gypsum powder. Then cool to 60 °C, add 2.5 kg of potassium persulfate as an initiator to the reaction vessel and stir for 8 min. Then add 90 kg of methacrylic acid, 55 kg of methacrylamide, and 0.5 kg of N-(hydroxymethyl)acrylamide as a crosslinking agent to the reaction vessel and stir for 110 min. Collect the gel product and wash it 4 times with deionized water, dry it, pulverize it, and pass it through a 70 mesh sieve to obtain water-absorbing resin powder.

[0045] Step 3: Add 45 kg of isophorone diisocyanate, 100 kg of polytetrahydrofuran, and 7 kg of polylactic acid to the reactor. Stir for 25 min at 65℃ and 180 r / min. Then add 0.3 kg of dibutyltin dilaurate as a catalyst to the reactor. Heat to 83℃ under nitrogen protection and stir for 2.3 h. Then add 155 kg of N,N-dimethylformamide and 11 kg of 1,4-butanediol to the reactor. Stir for 2.3 h and filter out the material. Wash three times with deionized water, dry, and pulverize to obtain biodegradable polymer particles. Use melt spinning to prepare fibers with a length of 15 mm from the biodegradable polymer particles. Then soak them in a hydrogen peroxide solution with a mass concentration of 11 g / L for 7 h, filter, and dry to obtain biodegradable short fibers.

[0046] Step 4: Mix 10 kg of water-absorbing resin powder and 45 kg of biodegradable short fibers in an airflow at a mass ratio of 1:4.5 to obtain a mixed carrier; prepare a protective agent by mixing 10 kg of fish protein and 8 kg of trehalose; add 8 kg of mixed carrier, 8 kg of protective agent and 100 L of fermentation broth into a stirred tank, and shake and adsorb for 14 h at a stirring speed of 170 r / min and a temperature of 30 ± 0.5℃; filter; dry with forced air until the moisture content of the water-absorbing resin powder is 33%; granulate continuously using a granulator; sieve to obtain bacterial agent particles with a particle size of 4 mm.

[0047] Step 5: Mix 15kg of microbial agent granules and 100kg of sodium humate to obtain a microbial fertilizer with high humic content.

[0048] Example 4

[0049] This embodiment provides a microbial fertilizer with high humic content, including the following implementation steps:

[0050] Step 1: The microbial strain consisted of *Bacillus aspergillus*, *Bacillus belye*, and *Priscilla*. The activated microbial strain was inoculated into a sterilized culture medium containing 30 g / L glucose, 25 g / L beef extract, 10 g / L peptone, and 3.2 g / L magnesium sulfate. The culture was carried out in a fermenter at 180 rpm and 30 ± 0.5 °C for 12 hours. During the fermentation, the pH was adjusted to 6.8 with ammonia water, yielding 1000 L of fermentation broth. The viable count of *Bacillus aspergillus* in the fermentation broth was >1.5 × 10⁻⁶. 10 CFU / mL, viable count of Bacillus belyssus > 1.5 × 10⁻⁶ 10 CFU / mL, Priestella viable count > 1.2 × 10⁻⁶ 10 CFU / mL.

[0051] Step 2: Add desulfurized gypsum powder and 10 times its weight of anhydrous ethanol to a stirred tank and stir to form a suspension. Then add 2 times its weight of silane coupling agent KH550 to the desulfurized gypsum powder and stir at 500 r / min for 6 h. Centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder. Add 12 kg of modified gypsum powder, 16 kg of cellulose, and 1000 L of deionized water to a reaction vessel and stir at 95 °C for 60 min under nitrogen protection to gelatinize the cellulose and mix it evenly with the modified gypsum powder. Then cool to 65 °C, add 2.5 kg of potassium persulfate as an initiator to the reaction vessel and stir for 10 min. Then add 100 kg of methacrylic acid, 60 kg of methacrylamide, and 0.5 kg of N-(hydroxymethyl)acrylamide as a crosslinking agent to the reaction vessel and stir for 120 min. Collect the gel product and wash it 5 times with deionized water. Dry, pulverize, and pass it through an 80 mesh sieve to obtain water-absorbing resin powder.

[0052] Step 3: Add 46 kg of isophorone diisocyanate, 100 kg of polytetrahydrofuran, and 8 kg of polylactic acid to the reactor. Stir at 70℃ and 200 r / min for 30 min. Then add 0.3 kg of dibutyltin dilaurate as a catalyst to the reactor. Heat to 85℃ under nitrogen protection and stir for 2.5 h. Then add 160 kg of N,N-dimethylformamide and 12 kg of 1,4-butanediol to the reactor. Stir for 2.5 h and filter out the material. Wash with deionized water three times, dry, and pulverize to obtain biodegradable polymer particles. Use melt spinning to prepare fibers with a length of 20 mm from the biodegradable polymer particles. Then soak them in a 12 g / L hydrogen peroxide solution for 8 h, filter, and dry to obtain biodegradable short fibers.

[0053] Step 4: Mix 10 kg of water-absorbing resin powder and 50 kg of biodegradable short fibers in an airflow at a mass ratio of 1:5 to obtain a mixed carrier; prepare a protective agent by mixing 10 kg of fish protein and 10 kg of trehalose; add 10 kg of mixed carrier, 10 kg of protective agent and 100 L of fermentation broth into a stirred tank, and shake and adsorb for 16 h at a stirring speed of 180 r / min and a temperature of 30 ± 0.5℃; filter; dry with forced air until the moisture content of the water-absorbing resin powder is 35%; granulate continuously using a granulator; sieve to obtain bacterial agent granules with a particle size of 5 mm.

[0054] Step 5: Mix 20kg of microbial agent granules and 100kg of sodium humate to obtain a microbial fertilizer with high humic content.

[0055] Comparative Example 1: Based on Example 4, the biodegradable short fibers in step three were not treated with hydrogen peroxide solution, while the remaining steps remained unchanged, to prepare a microbial fertilizer with high humic content.

[0056] Comparative Example 2: Based on Example 4, no protective agent was added in step four, while the remaining steps remained unchanged, and a microbial fertilizer with high humic content was prepared.

[0057] Comparative Example 3: Based on Example 4, no modified gypsum powder was added during step two when preparing the absorbent resin powder, while the remaining steps remained unchanged, resulting in a microbial fertilizer with high humic content.

[0058] Comparative Example 4: Based on Example 4, step four directly uses biodegradable short fibers instead of the mixed carrier, while the remaining steps remain unchanged, to prepare a microbial fertilizer with high humic content.

[0059] Comparative Example 5: Based on Example 4, step four directly uses water-absorbing resin powder instead of the mixing carrier, while the remaining steps remain unchanged, to prepare a microbial fertilizer with high humic content.

[0060] In the examples and comparative examples, melt spinning was performed using a single-screw extruder with a spinneret having an orifice diameter of 0.22 mm and a length diameter of 0.66 mm. The melt temperature of the biodegradable polymer particles was 235°C, and the temperatures of the single-screw extruder were 220°C in zone one, 230°C in zone two, 235°C in zone three, and 235°C in zone four.

[0061] The microbial strains are from the Institute of Soil and Fertilizer, Anhui Academy of Agricultural Sciences, and are deposited at the China General Microbiological Culture Collection Center (CGMCC). Specifically, *Bacillus aryabhattai* was deposited on March 9, 2022, at the CGMCC, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC NO. 24486; *Bacillus velezensis* was deposited on July 7, 2023, at the same location, with accession number CGMCC NO. 27827; and *Priestiaspis*... This strain was deposited on February 7, 2023, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC NO. 26518; the desulfurized gypsum powder was purchased from Zaozhuang Xinghao New Materials Co., Ltd.; the cellulose was hydroxypropyl methylcellulose purchased from Jinan Hengyu Chemical Co., Ltd.; methacrylic acid and methacrylamide were both purchased from Jinan Shiji Tongda Chemical Co., Ltd.; the polytetrahydrofuran with an average molecular weight of 2000 was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.; the polylactic acid was purchased from Wuhan Andomai New Energy Co., Ltd.; and the fish protein was purchased from Hebei Xiangniu Fertilizer Co., Ltd.

[0062] Performance tests were conducted on Examples 1-4 and Comparative Examples 1-5. 1g of the newly prepared microbial fertilizer from each group was placed in a test tube, and 9mL of sterile water was added. The mixture was shaken at 35℃ and 160r / min for 2 hours, then diluted with sterile water to obtain 1×10⁻⁶ microbial fertilizer. -8 1×10 -9 1×10 -10Three consecutive concentrations of dilution were used, with 0.1 mL of each dilution inoculated into commercially available agar medium and incubated at 30°C for 48 h. The initial viable count (A1) of the microbial fertilizer granules in different groups was counted using the plate counting method. Then, the same method was used to detect the total viable count (A2) of the microbial fertilizer granules in different groups after one week of application. The viable count retention rate was calculated (viable count retention rate = A2 / A1 × 100%). The results are shown in Table 1.

[0063] Table 1

[0064]

[0065] As shown in Table 1, adding modified gypsum powder, water-absorbing resin powder, and biodegradable short fibers can increase the adsorption capacity of bacteria and increase the retention rate of live bacteria.

[0066] A compacted experimental field was selected in Huaibei City, Anhui Province. The soil was dried to remove impurities and passed through a 16-mesh sieve. The soil's physicochemical properties were then tested, as shown in Table 2.

[0067] Table 2

[0068] Organic carbon content (g / kg) Available nitrogen content (mg / kg) Available phosphorus content (mg / kg) Available potassium content (mg / kg) pH 5.83 18.65 15.57 73.04 8.2

[0069] The experimental field was divided into 9 equal plots. Each plot was rotary tilled, and different microbial fertilizers were applied at a rate of 100 kg / mu. After ridging, healthy cotton seedlings with a plant height of 25-30 cm were transplanted at a spacing of 40 cm. Subsequent field management was the same. After the cotton bolls opened, 4 m sections were randomly selected from each experimental plot. 2 In a 2m × 2m area, after harvesting cotton fibers, the number of cotton plants, the number of cotton bolls, and the total weight were recorded in different areas. The number of bolls per plant and the average weight of the bolls were calculated. The results are shown in Table 3.

[0070] Table 3

[0071]

[0072] As shown in Table 3, the combination of water-absorbing resin powder and biodegradable short fibers, along with the addition of protective agents, helps to increase the number of bolls per plant and the average weight of bolls. This is because the microbial agent granules expand after application, reducing soil compaction, increasing the respiration of crop roots, and providing good support for the plants, thus helping to increase crop yield.

[0073] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a microbial fertilizer, characterized in that, Includes the following steps: Step 1: Inoculate the activated microbial strains into the sterilized culture medium and expand the culture in a fermenter to obtain the fermentation broth; Step 2: Add the mixed carrier, protectant and fermentation broth to the stirred tank at a ratio of 0.5-1g:0.5-1g:10mL, shake and adsorb at 30±0.5℃ and 150-180r / min for 12-16h, filter, and dry with forced air until the water content of the water-absorbing resin powder is 30-35%, continuously granulate, and sieve to obtain bacterial agent particles with a particle size of 2-5mm; Step 3: Mix the microbial agent granules and sodium humate at a mass ratio of 1-2:10 to obtain microbial fertilizer; The method for preparing the mixed carrier is as follows: water-absorbing resin powder and biodegradable short fibers are mixed by airflow at a mass ratio of 1:4-5 to obtain the mixed carrier; The protective agent is a mixture of fish protein and trehalose in a mass ratio of 1:0.5-1; The water-absorbing resin powder is prepared by the following steps: Modified gypsum powder, cellulose, and deionized water are added to a reaction vessel, and the mixture is stirred at 85-95℃ for 40-60 minutes under nitrogen protection. The temperature is then lowered to 55-65℃, potassium persulfate is added to the reaction vessel, and the mixture is stirred for 5-10 minutes. Then, methacrylic acid, methacrylamide, and a crosslinking agent are added, and the mixture is stirred for 100-120 minutes. The product is washed, dried, pulverized, and passed through a 60-80 mesh sieve to obtain water-absorbing resin powder. The modified gypsum powder is prepared through the following steps: Add desulfurized gypsum powder and 8-10 times the mass of anhydrous ethanol to a mixing tank and stir to form a suspension. Then add 1.5-2 times the mass of desulfurized gypsum powder and silane coupling agent KH550. Stir at 200-500 r / min for 4-6 h, centrifuge, dry the precipitate, and pulverize to obtain modified gypsum powder. The biodegradable short fibers are prepared through the following steps: Isophorone diisocyanate, polytetrahydrofuran, and polylactic acid were added to a reactor and stirred at 60-70℃ and 150-200 rpm for 20-30 minutes. Then, dibutyltin dilaurate was added, and the temperature was raised to 80-85℃ under nitrogen protection. The mixture was stirred and reacted for 2-2.5 hours. Next, N,N-dimethylformamide and 1,4-butanediol were added, and the mixture was stirred and reacted for 2-2.5 hours. The mixture was then filtered, washed, dried, and pulverized to obtain biodegradable polymer particles. These particles were then melt-spun into fibers with a length of 10-20 mm. The fibers were soaked in a 10-12 g / L hydrogen peroxide solution for 6-8 hours, filtered, and dried to obtain biodegradable short fibers.

2. The method for preparing a microbial fertilizer according to claim 1, characterized in that, The ratio of the modified gypsum powder, cellulose, deionized water, potassium persulfate, methacrylic acid, methacrylamide and crosslinking agent is 1-1.2g: 1.5-1.6g: 80-100mL: 0.25g: 8-10g: 5-6g: 0.05g.

3. The method for preparing a microbial fertilizer according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide or N-(hydroxymethyl)acrylamide.

4. The method for preparing a microbial fertilizer according to claim 1, characterized in that, The ratio of isophorone diisocyanate, polytetrahydrofuran, polylactic acid, dibutyltin dilaurate, N,N-dimethylformamide and 1,4-butanediol is 4.4-4.6g:10g:0.6-0.8g:0.03g:15-16g:1-1.2g.

5. The method for preparing a microbial fertilizer according to claim 1, characterized in that, The microbial strains consist of Bacillus aureus, Bacillus belyssus, and Priestella.

6. A microbial fertilizer, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

Images