Microbial fermentation organic fertilizer and preparation method thereof

Abstract

The invention discloses a microbial fermentation organic fertilizer and a preparation method thereof, and belongs to the technical field of microbial fertilizer.The preparation method comprises the steps that aerobic bacteria are adopted for composting of a mixture of cow dung and straw residues, an accelerant with oxygen release and heat conduction functions is prepared, and aerobic fermentation is conducted; the accelerant can effectively increase the oxygen content in the compost body and maintain the temperature of the compost body to be uniform, so that the problem of low fermentation efficiency caused by insufficient oxygen and uneven temperature in the compost body in a conventional composting method is solved, and the method has a good application prospect in the field of preparation of fermented organic fertilizers.

Description

Technical Field

[0001] This invention relates to the field of microbial fertilizer technology, and in particular to a microbial fermented organic fertilizer and its preparation method. Background Technology

[0002] Fertilizer is a crucial guarantee for grain production. In my country, by the 1990s, the proportion of chemical fertilizers in agricultural nutrient inputs reached an all-time high. However, the unreasonable and excessive application of chemical fertilizers, especially nitrogen fertilizers, has led to problems such as soil degradation, farmland pollution, and declining agricultural product quality, all of which negatively impact sustainable agricultural development. Consequently, the commercial organic fertilizer industry has experienced rapid growth, and the government has introduced numerous policies to encourage the utilization of agricultural waste as fertilizer and the development of the organic fertilizer industry.

[0003] Organic fertilizer preparation methods generally include high-temperature rapid drying, reactor fermentation, and composting fermentation. High-temperature rapid drying effectively kills pathogens and insect eggs in feces, has a short cycle, and is easy to scale up for industrial production, but it consumes a lot of energy, produces products with poor maturity, and kills some beneficial microorganisms in the material. Reactor fermentation is highly efficient, requires little space, and is suitable for industrial production, but it involves high fixed asset investment and energy consumption, and has a relatively small processing capacity. Composting fermentation is simple and easy to implement, ensuring product maturity and stable quality, and is a commonly used method in organic fertilizer production. Composting fermentation generally uses aerobic fermentation technology, specifically referring to the conversion of organic materials into carbon dioxide and small-molecule organic compounds under aerobic conditions using the life activities of aerobic microorganisms, thereby achieving the reduction and stabilization of organic materials. Aerobic fermentation has advantages such as high processing efficiency, high product resource utilization, and environmental friendliness. However, in the process of aerobic composting fermentation for organic fertilizer production, insufficient oxygen supply and uneven temperature within the compost pile often occur, leading to slow and uneven fermentation, affecting fermentation efficiency.

[0004] Therefore, it is currently necessary to find a suitable composting fermentation method to solve the problem of reduced fermentation efficiency caused by insufficient oxygen supply and uneven temperature inside the compost pile when producing organic fertilizer. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a microbial fermented organic fertilizer and its preparation method, which solves the problem of reduced fermentation efficiency caused by insufficient oxygen supply and uneven temperature inside the compost pile during the production of organic fertilizer.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] A microbial fermented organic fertilizer, wherein the organic fertilizer comprises the following raw materials in parts by weight:

[0008] 300-500 parts of manure, 100-200 parts of straw residue, 0.06-0.1 parts of microbial inoculant, 10-20 parts of rice bran, and 6-12 parts of accelerator.

[0009] Furthermore, the accelerator comprises the following raw materials:

[0010] Calcium peroxide, graphene, L-tryptophan, cetyl alcohol, p-toluenesulfonic acid, gelatin, sodium alginate, xanthan gum, nano magnesium oxide, ammonium bicarbonate, microcrystalline cellulose, succinic anhydride, EDC·HCl, N-hydroxysuccinimide, calcium chloride.

[0011] Furthermore, the excrement is any one or more of cow dung, pig dung, chicken dung, and sheep dung.

[0012] Furthermore, the microbial agent is obtained by mixing Bacillus subtilis and Bacillus amyloliquefaciens in a mass ratio of 4:3.

[0013] The present invention also discloses a method for preparing the organic fertilizer, the specific method of which is as follows:

[0014] (1) Dilute the microbial agent with water and add it to rice bran. Stir and mix evenly and let it stand for 1 day. Then add manure and straw residue and mix evenly to obtain compost.

[0015] (2) Adjust the carbon-nitrogen ratio of the compost to (25-30):1, adjust the moisture content to 65-70%, adjust the pH to 6.5-7.5, then add the accelerator, mix evenly, and compost.

[0016] (3) Turn the pile over every 3 to 5 days. Once the temperature of the pile remains stable and there is no obvious odor, it means that the composting fermentation is complete and the microbial fermented organic fertilizer product is obtained.

[0017] Furthermore, the method for preparing the accelerator is as follows:

[0018] A: Graphene was added to anhydrous ethanol and stirred to disperse it. L-tryptophan was then added and stirred continuously at 100-150 r / min for 18-24 h. Then, cetyl alcohol and p-toluenesulfonic acid were added, and the mixture was heated to 80℃ and stirred for 6-8 h. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered to remove the filtrate, washed 2-3 times with water, and dried at 45℃ to obtain modified graphene.

[0019] B: Microcrystalline cellulose was added to N,N-dimethylformamide and stirred to disperse. After adjusting the pH to 8, succinic anhydride was added, and the mixture was heated to 50°C and stirred for 4–6 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The filtrate was removed by filtration, and the mixture was washed 2–3 times with water. Then, it was dried at 60°C to constant weight to obtain pretreated microcrystalline cellulose. The pretreated microcrystalline cellulose was added to water and stirred to disperse. EDC·HCl and N-hydroxysuccinimide were added, and the pH was adjusted to 4.5–5.5. The mixture was stirred for 2–3 hours. After the reaction was completed, the filtrate was removed by filtration, and the mixture was washed 2–3 times with water. Then, it was dried at 45°C to obtain modified microcrystalline cellulose.

[0020] C: Dissolve ammonium bicarbonate in water by stirring, then add 5 times the mass of nano-magnesium oxide, stir evenly, and transfer to an oven. Dry at 60-80℃ until the water is completely evaporated to obtain a nano-magnesium oxide-ammonium bicarbonate mixture. Transfer the nano-magnesium oxide-ammonium bicarbonate mixture to a crucible and place it in a muffle furnace. Heat to 200-300℃ at a heating rate of 2-5℃ / min, and hold for 2-4 hours. Then cool naturally to room temperature and grind through a 200-300 mesh sieve to obtain porous magnesium oxide.

[0021] D: Add gelatin to 10 times its weight of water and stir to disperse. Then heat to 50°C and stir to dissolve. Add sodium alginate and xanthan gum and stir to dissolve to obtain a composite solution. Add porous magnesium oxide, modified microcrystalline cellulose and calcium peroxide to the composite solution and stir to mix evenly. Then add 2wt% calcium chloride solution for gelation. Then granulate to prepare particles with a particle size of 2-4 mm and wash twice with water to obtain primary particles.

[0022] E: Add modified graphene to 10 times its weight of water and stir to disperse to obtain modified graphene dispersion. Spray the modified graphene dispersion onto the surface of primary particles, dry at 60℃ for 10 min, then spray a second time, and then dry at 60℃ to constant weight to obtain accelerator.

[0023] In conventional composting processes for producing organic fertilizer, insufficient oxygen and uneven temperature within the compost pile can lead to reduced fermentation efficiency. Calcium peroxide, an oxygen-releasing agent, can be added to the compost pile for co-fermentation to slowly hydrolyze and release oxygen, thereby increasing the oxygen concentration and addressing the problem of insufficient oxygen leading to reduced composting efficiency. Graphene, a material with excellent thermal conductivity, can be added to the compost pile to efficiently conduct heat, ensuring uniform temperature and thus addressing the problem of uneven temperature causing reduced fermentation efficiency. However, directly adding calcium peroxide to the compost pile will generate calcium hydroxide during the slow hydrolysis and oxygen release. Calcium hydroxide is a strongly alkaline bactericide that reduces the activity of microorganisms in the compost pile, thereby affecting the decomposition of materials by microorganisms. Therefore, this invention uses calcium peroxide, graphene, gelatin, sodium alginate and other raw materials to prepare a promoter with good oxygen release and heat conduction functions, which is added to the pile to carry out the fermentation production of organic fertilizer. This effectively solves the problems of insufficient oxygen supply and uneven temperature in the pile, which lead to reduced fermentation efficiency, while not having an adverse effect on the microorganisms in the pile.

[0024] Specifically, this invention uses a mixture of gelatin, sodium alginate, and xanthan gum to prepare a composite adhesive solution. After adding calcium peroxide and mixing thoroughly, it is cross-linked with calcium chloride to obtain primary particles of calcium peroxide encapsulated in a composite gel. Modified graphene is then sprayed onto the surface to obtain an accelerator. When the accelerator is added to the reactor core, since the oxygen content is relatively high in the initial stage, there is no need for calcium peroxide to provide additional oxygen. Prematurely releasing oxygen from calcium peroxide would not meet the oxygen supply requirements in the later stages. However, this invention, by spraying modified graphene, can form a hydrophobic layer on the surface of the accelerator particles, inhibiting the entry of water molecules into the accelerator in the early stages, thereby suppressing the hydrolysis of calcium peroxide in the accelerator.

[0025] As composting progresses, the oxygen in the compost pile gradually decreases due to microbial activity, while the pile temperature gradually rises. At this point, the gelatin in the composite gel of the accelerator is temperature-sensitive; as the temperature increases, it undergoes sol-gelation and dispersion, leading to the collapse and dispersion of the accelerator particles. This causes the surface graphene layer to lose its hydrophobic barrier function, exposing the composite gel and absorbing moisture from the pile. This, in turn, causes the embedded calcium peroxide to hydrolyze upon contact with water, releasing oxygen to maintain the oxygen concentration in the pile. Meanwhile, the graphene, with its thermal conductivity, maintains the uniformity of the pile temperature. Furthermore, because the calcium peroxide remains embedded in the xanthan gum and sodium alginate gel within the composite gel, its hydrolysis product, calcium hydroxide, does not directly contact the microorganisms, thus avoiding its inhibitory effect on microbial activity.

[0026] This invention utilizes a composite gel prepared from xanthan gum, sodium alginate, and gelatin to encapsulate calcium peroxide. Xanthan gum and sodium alginate can form a denser network structure with gelatin through hydrogen bonding and electrostatic interactions, thereby increasing the gelation temperature of the gelatin. Consequently, gelation only occurs when the compost pile temperature enters the medium-high temperature fermentation stage, triggering the collapse of the accelerator particle structure and causing calcium peroxide to hydrolyze and release oxygen, thus ensuring the oxygen supply needs during the critical medium-high temperature period of composting. On the other hand, while the gelatin gelles and disperses, causing the accelerator structure to collapse, the sodium alginate and xanthan gum in the composite gel can still maintain the encapsulation of calcium peroxide. Therefore, even after calcium peroxide hydrolyzes to form calcium hydroxide, a gel isolation layer still exists to prevent calcium hydroxide from directly contacting microorganisms, thereby solving the problem of the inhibition of microbial activity by calcium peroxide hydrolysis products.

[0027] Although the preparation of gels by combining gelatin with xanthan gum and sodium alginate can increase their sol-gelation temperature, the denser network structure of the composite gel strongly hinders the entry of water into the composite gel, thus affecting the hydrolysis of calcium peroxide and the release of oxygen generated by hydrolysis. Therefore, this invention adds modified microcrystalline cellulose to the composite gel layer. The modified microcrystalline cellulose forms capillary pores in the composite gel through interlacing, thereby creating a more developed network structure. On the one hand, this allows for the containment of more water to hydrolyze the internal calcium peroxide and release oxygen; on the other hand, the developed pore structure ensures the diffusion and release of oxygen during hydrolysis.

[0028] Furthermore, while the composite gel absorbs moisture, causing the internal calcium peroxide to hydrolyze, the early decomposition of organic materials in the compost pile produces a large amount of organic acids. When the compost enters the medium-high temperature fermentation stage, microorganisms further decompose these organic acids. However, during this medium-high temperature stage, the composite gel absorbs moisture while simultaneously absorbing more organic acids, and the internal calcium peroxide generates hydrogen peroxide in an acidic environment, inhibiting microbial activity. Therefore, this invention also adds porous magnesium oxide to the composite gel. Porous magnesium oxide can react with the acid entering the accelerator, converting it into salt, thereby inhibiting hydrogen peroxide generation. Simultaneously, porous magnesium oxide further increases the porosity of the composite gel, further ensuring the entry of water molecules and the diffusion of oxygen released during the hydrolysis of calcium peroxide.

[0029] Furthermore, in step A, the mass ratio of graphene, L-tryptophan, hexadecyl alcohol, and p-toluenesulfonic acid is (0.3-0.5):(0.1-0.2):(0.1-0.2):(0.02-0.04).

[0030] Furthermore, in step B, the mass ratio of microcrystalline cellulose to succinic anhydride is (0.2-0.4):(0.1-0.2).

[0031] Furthermore, in step B, the mass ratio of pretreated microcrystalline cellulose, EDC·HCl, and N-hydroxysuccinimide is (0.2-0.4):(0.1-0.2):(0.05-0.1).

[0032] Furthermore, in step D, the mass ratio of gelatin, sodium alginate, xanthan gum, porous magnesium oxide, modified microcrystalline cellulose, calcium peroxide, and calcium chloride solution is (10-15):(1.25-1.8):(0.6-0.9):(0.4-0.6):(0.2-0.4):(5-8):(0.05-0.1).

[0033] Furthermore, in step E, the amount of modified graphene dispersion sprayed each time is 5 to 10% of the mass of the primary particles.

[0034] Beneficial effects:

[0035] This invention discloses the preparation of a promoter with high-efficiency oxygen release and thermal conductivity, which is mixed into the compost pile and fermented together with cow dung, straw residue, etc. The promoter can ensure a sufficient oxygen supply for aerobic fermentation bacteria and conduct internal heat to ensure temperature uniformity, thereby promoting the fermentation and maturation of compost and improving the fermentation efficiency. It has good application prospects in the field of composting fermentation. Detailed Implementation

[0036] The present invention will be described in detail below with reference to specific embodiments:

[0037] This invention discloses a microbial fermented organic fertilizer and its preparation method. Before preparing the fermented organic fertilizer, it is necessary to prepare an accelerator, as shown below.

[0038] Example 1: Preparation of Accelerator

[0039] A: 0.4 kg of graphene was added to 12 kg of anhydrous ethanol and stirred to disperse. Then 0.15 kg of L-tryptophan was added and stirred continuously at 120 r / min for 20 h. Then 0.15 kg of cetyl alcohol and 0.03 kg of p-toluenesulfonic acid were added, and the temperature was raised to 80 °C and stirred for 7 h. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered to remove the filtrate, washed three times with water, and dried at 45 °C to obtain modified graphene.

[0040] B: Add 0.3 kg of microcrystalline cellulose to 3 kg of N,N-dimethylformamide and stir to disperse. Adjust the pH to 8, then add 0.15 kg of succinic anhydride. Heat to 50 °C and stir to react for 5 h. After the reaction is complete, allow to cool naturally to room temperature, filter to remove the filtrate, wash three times with water, and then dry at 60 °C to constant weight to obtain pretreated microcrystalline cellulose. Add 0.3 kg of pretreated microcrystalline cellulose to 3 kg of water and stir to disperse. Add 0.15 kg of EDC·HCl and 0.07 kg of N-hydroxysuccinimide, adjust the pH to 5, and stir to react for 2.5 h. After the reaction is complete, filter to remove the filtrate, wash three times with water, and then dry at 45 °C to obtain modified microcrystalline cellulose.

[0041] C: Add ammonium bicarbonate to water and stir to dissolve. Then add 5 times the mass of nano-magnesium oxide, stir evenly, and transfer to an oven. Dry at 65°C until the water evaporates completely to obtain a nano-magnesium oxide-ammonium bicarbonate mixture. Transfer the nano-magnesium oxide-ammonium bicarbonate mixture to a crucible and place it in a muffle furnace. Heat to 250°C at a heating rate of 4°C / min and hold for 3 hours. Then cool naturally to room temperature and grind through a 250-mesh sieve to obtain porous magnesium oxide.

[0042] D: Add 12kg of gelatin to 10 times its weight of water, stir to disperse, heat to 50℃ and stir to dissolve. Then add 1.5kg of sodium alginate and 0.75kg of xanthan gum and stir to dissolve to obtain a composite solution. Add 0.5kg of porous magnesium oxide, 0.3kg of modified microcrystalline cellulose and 7kg of calcium peroxide to the composite solution, stir to mix evenly, and then add 0.08kg of 2wt% calcium chloride solution for gelation. Then granulate to prepare particles with a particle size of about 4mm and wash twice with water to obtain primary particles.

[0043] E: Add modified graphene to 10 times its mass of water and stir to disperse to obtain modified graphene dispersion. Spray the modified graphene dispersion onto the surface of primary particles, dry at 60℃ for 10 min, and then spray a second time. The amount of modified graphene dispersion sprayed each time is 8% of the mass of primary particles. Then dry at 60℃ to constant weight to obtain accelerator.

[0044] Example 2: Preparation of Accelerator II

[0045] A: Add 0.3 kg of graphene to 9 kg of anhydrous ethanol and stir to disperse. Then add 0.1 kg of L-tryptophan and stir continuously at 100 r / min for 18 h. Then add 0.1 kg of cetyl alcohol and 0.02 kg of p-toluenesulfonic acid. Heat to 80 °C and stir to react for 6 h. After the reaction is complete, cool naturally to room temperature, filter to remove the filtrate, wash twice with water and dry at 45 °C to obtain modified graphene.

[0046] B: Add 0.2 kg of microcrystalline cellulose to 2 kg of N,N-dimethylformamide and stir to disperse. Adjust the pH to 8, then add 0.1 kg of succinic anhydride. Heat to 50 °C and stir to react for 4 h. After the reaction is complete, allow to cool naturally to room temperature, filter to remove the filtrate, wash twice with water, and then dry at 60 °C to constant weight to obtain pretreated microcrystalline cellulose. Add 0.2 kg of pretreated microcrystalline cellulose to 2 kg of water and stir to disperse. Add 0.1 kg of EDC·HCl and 0.05 kg of N-hydroxysuccinimide, adjust the pH to 4.5, and stir to react for 2 h. After the reaction is complete, filter to remove the filtrate, wash twice with water, and then dry at 45 °C to obtain modified microcrystalline cellulose.

[0047] C: Add ammonium bicarbonate to water and stir to dissolve. Then add 5 times the mass of nano-magnesium oxide, stir evenly, and transfer to an oven. Dry at 60°C until the water evaporates completely to obtain a nano-magnesium oxide-ammonium bicarbonate mixture. Transfer the nano-magnesium oxide-ammonium bicarbonate mixture to a crucible and place it in a muffle furnace. Heat to 200°C at a heating rate of 3°C / min and hold for 2 hours. Then cool naturally to room temperature and grind through a 200-mesh sieve to obtain porous magnesium oxide.

[0048] D: Add 10 kg of gelatin to 10 times its weight of water, stir to disperse, heat to 50℃ and stir to dissolve. Then add 1.25 kg of sodium alginate and 0.6 kg of xanthan gum and stir to dissolve to obtain a composite solution. Add 0.4 kg of porous magnesium oxide, 0.2 kg of modified microcrystalline cellulose and 5 kg of calcium peroxide to the composite solution, stir to mix evenly, add 0.05 kg of 2 wt% calcium chloride solution to gel, then granulate to prepare particles with a particle size of about 3 mm, and wash twice with water to obtain primary particles.

[0049] E: Add modified graphene to 10 times its mass of water and stir to disperse to obtain modified graphene dispersion. Spray the modified graphene dispersion onto the surface of primary particles, dry at 60℃ for 10 min, and then spray a second time. The amount of modified graphene dispersion sprayed each time is 6% of the mass of primary particles. Then dry at 60℃ to constant weight to obtain accelerator.

[0050] Example 3: Preparation of Accelerator

[0051] A: Add 0.5 kg of graphene to 15 kg of anhydrous ethanol and stir to disperse. Then add 0.2 kg of L-tryptophan and stir continuously at 150 r / min for 24 h. Then add 0.2 kg of cetyl alcohol and 0.04 kg of p-toluenesulfonic acid. Heat to 80 °C and stir to react for 8 h. After the reaction is complete, cool naturally to room temperature, filter to remove the filtrate, wash with water 3 times and dry at 45 °C to obtain modified graphene.

[0052] B: Add 0.4 kg of microcrystalline cellulose to 4 kg of N,N-dimethylformamide and stir to disperse. Adjust the pH to 8, then add 0.2 kg of succinic anhydride. Heat to 50°C and stir to react for 6 h. After the reaction is complete, allow to cool naturally to room temperature, filter to remove the filtrate, wash three times with water, and then dry at 60°C to constant weight to obtain pretreated microcrystalline cellulose. Add 0.4 kg of pretreated microcrystalline cellulose to 4 kg of water and stir to disperse. Add 0.2 kg of EDC·HCl and 0.1 kg of N-hydroxysuccinimide, adjust the pH to 5.5, and stir to react for 3 h. After the reaction is complete, filter to remove the filtrate, wash three times with water, and then dry at 45°C to obtain modified microcrystalline cellulose.

[0053] C: Add ammonium bicarbonate to water and stir to dissolve. Then add 5 times the mass of nano-magnesium oxide, stir evenly, and transfer to an oven. Dry at 80°C until the water evaporates completely to obtain a nano-magnesium oxide-ammonium bicarbonate mixture. Transfer the nano-magnesium oxide-ammonium bicarbonate mixture to a crucible and place it in a muffle furnace. Heat to 300°C at a heating rate of 5°C / min and hold for 4 hours. Then cool naturally to room temperature and grind through a 300-mesh sieve to obtain porous magnesium oxide.

[0054] D: Add 15kg of gelatin to 10 times its weight of water, stir to disperse, heat to 50℃ and stir to dissolve. Then add 1.8kg of sodium alginate and 0.9kg of xanthan gum and stir to dissolve to obtain a composite solution. Add 0.6kg of porous magnesium oxide, 0.4kg of modified microcrystalline cellulose and 8kg of calcium peroxide to the composite solution, stir to mix evenly, add 0.1kg of 2wt% calcium chloride solution to gel, then granulate to prepare particles with a particle size of 4mm, and wash twice with water to obtain primary particles.

[0055] E: Add modified graphene to 10 times its mass of water and stir to disperse to obtain modified graphene dispersion. Spray the modified graphene dispersion onto the surface of primary particles, dry at 60℃ for 10 min, and then spray a second time. The amount of modified graphene dispersion sprayed each time is 10% of the mass of primary particles. Then dry at 60℃ to constant weight to obtain accelerator.

[0056] Comparative Example 1: Preparation of Accelerator

[0057] Compared with Example 1, the only difference is that step A is missing in the preparation of the accelerator in Comparative Example 1, that is, no modification treatment is performed on the graphene. In step E, conventional graphene dispersion can be directly sprayed. All other steps are the same as in Example 1.

[0058] Comparative Example 2: Preparation of Accelerator

[0059] Compared with Example 1, the only difference is that step B is missing in the preparation of the accelerator in Comparative Example 2. That is, the microcrystalline cellulose is not modified and conventional microcrystalline cellulose is added directly in step D. The remaining steps are the same as in Example 1.

[0060] Comparative Example 3: Preparation of Accelerator

[0061] Compared with Example 1, the only difference is that step C is missing in the preparation of the accelerator in Comparative Example 3. Instead of processing the nano magnesium oxide to prepare porous magnesium oxide, the nano magnesium oxide is added directly in step D. All other steps are the same as in Example 1.

[0062] Comparative Example 4: Preparation of Accelerator

[0063] Compared with Example 1, the only difference is that sodium alginate was not added in step D of the preparation of the accelerator in Comparative Example 4. Instead, sodium alginate was replaced with an equal amount of gelatin. All other steps were the same as in Example 1.

[0064] Comparative Example 5: Preparation of Accelerator

[0065] Compared with Example 1, the only difference is that in the preparation of the accelerator in Comparative Example 5, xanthan gum is not added in step D, but is replaced with an equal amount of gelatin. All other steps are the same as in Example 1.

[0066] Comparative Example 6: Preparation of Accelerator

[0067] Compared with Example 1, the only difference is that in the preparation of the accelerator in Comparative Example 6, gelatin is not used in step D, but is replaced with an equal amount of sodium alginate. All other steps are the same as in Example 1.

[0068] Comparative Example 7: Preparation of Accelerator

[0069] Compared with Example 1, the only difference is that porous magnesium oxide was not added in step D during the preparation of the accelerator in Comparative Example 7, while the other steps were the same as in Example 1.

[0070] Comparative Example 8: Preparation of Accelerator

[0071] Compared with Example 1, the only difference is that modified microcrystalline cellulose was not added in step D of the preparation of the accelerator in Comparative Example 8, while the other steps were the same as in Example 1.

[0072] Example 4: Preparation of Fermented Organic Fertilizer

[0073] (1) Bacillus subtilis and Bacillus amyloliquefaciens were mixed in a mass ratio of 4:3 to obtain a microbial agent. The viable count of Bacillus subtilis and Bacillus amyloliquefaciens was about 2×109 cfu / g. 0.08 kg of the microbial agent was diluted with 100 times the mass of water and then added to 10 kg of rice bran. The mixture was stirred and mixed evenly and left to stand for 1 day. Then, 300 kg of manure and 100 kg of straw residue were added and mixed evenly to obtain the compost.

[0074] (2) Adjust the carbon-nitrogen ratio of the compost to 26:1, adjust the moisture content to 68%, adjust the pH to 7, and then add 7 kg of the accelerator prepared according to Example 3. After mixing evenly, make a pile with a width and height of about 1 m and a length determined according to the amount of compost for composting.

[0075] (3) Turn the pile over every 5 days. Once the temperature of the pile remains stable and there is no obvious odor, the composting fermentation is complete and the microbial fermented organic fertilizer product is obtained.

[0076] Experiment: Fermentation and composting of organic fertilizer

[0077] 1. The accelerators prepared in Example 1 and Comparative Examples 1-8 were used to conduct composting experiments on fermented organic fertilizer. The experiments were conducted in an open space in Xide County, Liangshan Prefecture, and were divided into 10 groups: experimental group 1, control group 1-8, and blank control group.

[0078] Experimental group 1 used the accelerator prepared in Example 1 and the composting method in Example 4;

[0079] Control groups 1-8 used the accelerators prepared in comparative examples 1-8 and the composting method of Example 4, respectively;

[0080] The blank control group did not use an accelerator, but instead directly added 2.3 kg of calcium peroxide and 0.3 kg of graphene, mixed evenly, and composted according to the method in Example 4.

[0081] 2. During the composting experiments in each group, the carbon-to-nitrogen ratio of the compost was 26:1, the moisture content was 68%, and the pH was 7.

[0082] 3. On day 10 of composting, the oxygen content in the compost pile was measured; on day 15 of composting, the temperature difference between the center of the compost pile and the outer layer of the compost pile (10 cm from the surface inward) was measured; the composting time of each group was recorded; and the germination index of cucumber seeds of each group of fermented compost products was measured.

[0083] The germination index detection method is as follows:

[0084] Weigh 10g of air-dried organic fertilizer product into a 250mL Erlenmeyer flask, add 100mL of water, tighten the cap, and fix it vertically on a reciprocating horizontal shaker. Adjust the frequency to 100 times / min and the amplitude to 50mm, and shake and extract at 25℃ for 1 hour. Then remove the flask, let it stand for 30 minutes, and filter the supernatant. Collect the filtered extract. Place a filter paper in a petri dish, and evenly place 20 uniform, plump cucumber seeds on it. Add 10mL of the extract, cover the petri dish, and incubate in a 25℃ incubator in the dark for 48 hours. Calculate the germination rate and measure the taproot length. Use water as a control for a blank experiment, and then calculate the seed germination index for each group. Three replicates were performed for each group, and the average data are shown in Table 1.

[0085] Table 1

[0086]

[0087] Based on the data analysis in Table 1, we can conclude that:

[0088] (1) In experimental group 1 of this invention, the oxygen content in the organic fertilizer pile on the 10th day of fermentation was 15%, the temperature difference between the inside and outside of the pile was only 7.3℃, the fermentation time was 21 days, and the germination index reached 93.2%. This shows that the method of this invention for preparing fermented organic fertilizer can effectively solve the problems of insufficient oxygen content and uneven temperature in the pile, the fermentation time is short, and the fermented fertilizer product obtained has a high degree of decomposition. The germination index of cucumber seeds can reach 93.2%. In contrast, in the blank control group, when calcium peroxide and graphene were directly added, the oxygen content on the 10th day of fermentation decreased to 6%, the decomposition time increased to 28 days, and the seed germination index decreased to 84.5%. Since the blank control group did not undergo any modification treatment on the graphene, its thermal conductivity remained good. Compared with the experimental group 1, the temperature difference between the inside and outside of the stack was reduced by 0.3℃. The experimental group 1 used L-tryptophan to be adsorbed onto the graphene surface through π-π stacking and then combined with octadecyl alcohol through ester bonds and other reactions to prepare a more hydrophobic modified graphene. Since the π-π stacking did not deeply modify the graphene, its impact on its thermal conductivity was very small and negligible.

[0089] (2) In control group 1, the graphene was not modified during the preparation of the accelerator. The lack of hydrophobicity in the early stage of the accelerator led to premature hydrolysis of calcium peroxide due to water absorption. By day 10, the oxygen content decreased significantly during the high-temperature fermentation period. In control group 2, the microcrystalline cellulose was not modified during the preparation of the accelerator. The addition of microcrystalline cellulose led to a decrease in the stability of the gel structure. Instead, premature sol-gelation caused premature hydrolysis of calcium peroxide and oxygen release. By day 10 of fermentation, the oxygen concentration decreased to 12. In contrast, the experimental group used succinic anhydride and N-hydroxysuccinimide to sequentially modify the microcrystalline cellulose, enabling it to covalently bind with gelatin through nucleophilic substitution reaction, thereby improving the stability of gelatin and working together with xanthan gum to increase the sol-gelation temperature and inhibit the premature oxygen release of the accelerator. In control group 3, nano-magnesium oxide was directly used during the preparation of the accelerator. The reaction binding of the accelerator with organic acids in the pile was reduced, which affected the microbial activity and reduced the smooth progress of water entry and oxygen escape of the accelerator.

[0090] (3) No sodium alginate was added during the preparation of the accelerator in control group 4; no xanthan gum was added during the preparation of the accelerator in control group 5. The reduced sol-gelation temperature of the composite gel in control groups 4 and 5 led to the premature release of the accelerator, resulting in a slight decrease in oxygen concentration on the 10th day of fermentation; no gelatin was used during the preparation of the accelerator in control group 6. The lack of gelatin in the sol-gelation disintegration accelerator structure greatly reduced the effectiveness of the accelerator; no porous magnesium oxide was added during the preparation of the accelerator in control group 7; no modified microcrystalline cellulose was added during the preparation of the accelerator in control group 8. The entry of water and the escape of oxygen were hindered in control groups 7 and 8. In particular, the lack of magnesium oxide in control group 7 led to the removal of organic acids, which in turn caused the decomposition of calcium peroxide to produce hydrogen peroxide, affecting the activity of microorganisms and significantly increasing the fermentation time.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A microorganism fermented organic fertilizer, characterized by, The organic fertilizer comprises the following raw materials in mass parts: feces 300-500 parts, straw residue 100-200 parts, microbial agent 0.06-0.1 part, rice bran 10-20 parts, and accelerator 6-12 parts.

2. The microorganism fermentation organic fertilizer according to claim 1, characterized in that, The accelerator comprises the following raw materials: calcium peroxide, graphene, L-tryptophan, cetyl alcohol, p-toluenesulfonic acid, gelatin, sodium alginate, xanthan gum, nano-magnesium oxide, ammonium bicarbonate, microcrystalline cellulose, succinic anhydride, EDC·HCl, N-hydroxysuccinimide, and calcium chloride.

3. The microorganism fermentation organic fertilizer according to claim 2, characterized in that, The microbial agent is obtained by mixing Bacillus subtilis and Bacillus amyloliquefaciens at a mass ratio of 4:

3.

4. A method for preparing a microbial fermentation organic fertilizer, characterized in that, The preparation method of the organic fertilizer is as follows: (1) the microbial agent is diluted with water, then added to rice bran, stirred and mixed uniformly, and allowed to stand for 1 day, then feces and straw residue are added and mixed uniformly to obtain a pile; (2) the carbon-nitrogen ratio of the pile is adjusted to (25-30):1, the water content is adjusted to 65-70%, the pH is adjusted to 6.5-7.5, then the accelerator is added and mixed uniformly to prepare a pile for composting; (3) the pile is turned over every 3-5 days, and when the pile temperature remains stable and there is no obvious odor, it indicates that the composting fermentation is completed, and the microbial fermentation organic fertilizer product is obtained.

5. The method according to claim 4, wherein the microorganism is a fungus. The preparation method of the accelerator is as follows: A: graphene is added to anhydrous ethanol and stirred and dispersed, then L-tryptophan is added, and stirring is continued at a speed of 100-150 r / min for 18-24 h, then cetyl alcohol and p-toluenesulfonic acid are added, and stirring is carried out at 80℃ for 6-8 h, after the reaction is completed, the mixture is naturally cooled to room temperature, the filtrate is removed by filtration, then washed with water for 2-3 times, and dried at 45℃ to obtain modified graphene; B: microcrystalline cellulose is added to N,N-dimethylformamide and stirred and dispersed, the pH is adjusted to 8, then succinic anhydride is added, and stirring is carried out at 50℃ for 4-6 h, after the reaction is completed, the mixture is naturally cooled to room temperature, the filtrate is removed by filtration, then washed with water for 2-3 times, and dried at 60℃ to constant weight to obtain pretreated microcrystalline cellulose; pretreated microcrystalline cellulose is added to water and stirred and dispersed, then EDC·HCl and N-hydroxysuccinimide are added, the pH is adjusted to 4.5-5.5, and stirring is carried out for 2-3 h, after the reaction is completed, the filtrate is removed by filtration, then washed with water for 2-3 times, and dried at 45℃ to obtain modified microcrystalline cellulose; C: ammonium bicarbonate is added to water and stirred and dissolved, then 5 times the mass of nano-magnesium oxide is added, stirred and uniformly transferred to an oven, dried at 60-80℃ until the water is completely evaporated to obtain a nano-magnesium oxide-ammonium bicarbonate mixture; the nano-magnesium oxide-ammonium bicarbonate mixture is transferred to a crucible and placed in a muffle furnace, heated to 200-300℃ at a heating rate of 2-5℃ / min, and kept at this temperature for 2-4 h, then naturally cooled to room temperature, and ground through a 200-300 mesh sieve to obtain porous magnesium oxide. D: gelatin is added into 10 times mass of water, stirred and dispersed, heated to 50℃, stirred and dissolved, then sodium alginate and xanthan gum are added, stirred and dissolved to obtain a composite glue solution, porous magnesium oxide, modified microcrystalline cellulose and calcium peroxide are added into the composite glue solution, stirred and mixed uniformly, then 2wt% calcium chloride solution is added for gelation, then granulation is carried out to prepare granules with a particle size of 2-4mm, then the granules are washed with water for 2 times to obtain primary granules; E: modified graphene is added into 10 times mass of water, stirred and dispersed to obtain a modified graphene dispersion, the modified graphene dispersion is sprayed onto the surface of the primary granules, dried at 60℃ for 10min, then secondary spraying is carried out, then the mixture is dried at 60℃ until constant weight to obtain a promoter.

6. The method according to claim 5, wherein the microorganism is a fungus. The mass ratio of graphene, L-tryptophan, cetyl alcohol and p-toluenesulfonic acid in step A is (0.3-0.5):(0.1-0.2):(0.1-0.2):(0.02-0.04).

7. The method according to claim 6, wherein the microorganism is a fungus. The mass ratio of microcrystalline cellulose and succinic anhydride in step B is (0.2-0.4):(0.1-0.2).

8. The method according to claim 7, wherein the microorganism is a fungus. The mass ratio of pretreated microcrystalline cellulose, EDC·HCl and N-hydroxysuccinimide in step B is (0.2-0.4):(0.1-0.2):(0.05-0.1).

9. The method according to claim 8, wherein the microorganism is a fungus. The mass ratio of gelatin, sodium alginate, xanthan gum, porous magnesium oxide, modified microcrystalline cellulose, calcium peroxide and calcium chloride solution in step D is (10-15):(1.25-1.8):(0.6-0.9):(0.4-0.6):(0.2-0.4):(5-8):(0.05-0.1).

10. The method according to claim 9, wherein the microorganism is a fungus. The spraying amount of the modified graphene dispersion in step E is 5-10% of the mass of the primary granules.

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