Microbial agent for low-temperature degradation of straw, straw decomposition organic fertilizer and application of microbial agent and straw decomposition organic fertilizer

Abstract

The invention belongs to the technical field of microorganisms, and particularly relates to a microbial agent for low-temperature degradation of straw, a straw decomposition organic fertilizer and application of the straw decomposition organic fertilizer. The invention provides a microbial agent for low-temperature degradation of straws, and the microbial agent comprises Aspergillus niger spores and Penicillium oxalicum spores, and is characterized in that the microbial agent comprises Aspergillus niger spores, Penicillium oxalicum spores, Aspergillus niger spores and Penicillium oxalicum spores. Aspergillus niger and penicillium oxalicum belong to phosphate-solubilizing fungi, are acidophilic filamentous fungi, can secrete organic acids (such as oxalic acid and citric acid) and efficient degrading enzymes, can maintain activity in a low-temperature environment of 4 DEG C, and break through the temperature limitation of traditional microorganisms. The microbial agent provided by the invention can accelerate straw decomposition conversion efficiency, effectively reduce agricultural non-point source pollution load, promote farmland carbon-nitrogen circulation, and finally realize collaborative development of crop yield increase and ecological environment protection.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and particularly relates to a microbial agent for low-temperature degradation of straw, a straw-decomposing organic fertilizer and applications thereof. Background Art

[0002] Crop straw is a core by-product of agricultural production. As the main organic waste, its large-scale treatment directly affects the sustainable development of agriculture and the ecological balance. Although returning straw to the field can reduce environmental pollution and improve soil fertility, it is limited by its degradation efficiency in low-temperature environments. Existing technologies mostly focus on medium- and high-temperature conditions (25-40°C). At low temperatures (4°C), the three-dimensional structure formed by lignin and cellulose is difficult to be effectively decomposed by conventional microorganisms, resulting in straw degradation and retention in autumn and winter, affecting subsequent farming and crop growth.

[0003] Traditional biological treatment relies on bacterial and fungal xylases, but their low-temperature activity is generally limited, making it difficult to meet seasonal needs. While chemical treatment can accelerate decomposition, it suffers from high energy consumption and byproduct pollution, contradicting the concept of green agriculture. Therefore, there is an urgent need to develop efficient, low-temperature-adaptable biodegradation agents to overcome the technical bottlenecks in straw resource utilization and achieve both environmental friendliness and agricultural profitability. Summary of the Invention

[0004] The purpose of the present invention is to provide a microbial agent for low-temperature degradation of straw, a straw-decomposing organic fertilizer and applications thereof. The microbial agent of the present invention can promote the degradation rate of straw in autumn and winter, improve the utilization rate of straw resources, reduce the pollution of crop straw to the environment, and realize the efficient utilization of straw resources.

[0005] The present invention provides a microbial agent for low-temperature degradation of straw, comprising Aspergillus niger spores and Penicillium oxalicum spores; the volume ratio of the Aspergillus niger spores to the Penicillium oxalicum spores is 1-2:1-2;

[0006] The concentration of Aspergillus niger spores is 1×10 8 ~9×10 8 CFU / mL; the concentration of the spores of Penicillium oxalicum was 1×10 8 ~9×10 8 CFU / mL.

[0007] As a preferred embodiment, the Aspergillus niger includes Aspergillus niger AH-F-1-2, and the preservation number of the Aspergillus niger AH-F-1-2 is CGMCC No. 23272; the Penicillium oxalicum includes Penicillium oxalicum AH-F-2-7, and the preservation number of the Penicillium oxalicum AH-F-2-7 is CGMCC No. 22475.

[0008] As a preferred embodiment, the microbial agent further comprises phosphate and fertilizer synergist;

[0009] The phosphate includes at least one of iron phosphate, aluminum phosphate and tricalcium phosphate;

[0010] The fertilizer synergist includes at least one of fulvic acid, glutamic acid and alginic acid.

[0011] As a preferred embodiment, the amount of the phosphate added is 40% to 1000% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores; the amount of the fertilizer synergist added is 5% to 50% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores.

[0012] The present invention also provides a method for preparing straw decomposition organic fertilizer, comprising mixing the microbial agent described in the above scheme with a fermentation base material, and fermenting for 15 to 28 days to obtain straw decomposition organic fertilizer;

[0013] The amount of the microbial agent added is 2% to 10% based on the mass of the fermentation base;

[0014] The fermentation base material includes straw and livestock excrement; the mass ratio of the straw to the livestock excrement is 3:7 to 4:6.

[0015] As a preferred solution, the water content of the fermentation base is 55% to 65%; the carbon-nitrogen ratio of the fermentation base is 25 to 30:1; and the fermentation temperature is 30 to 65°C.

[0016] As a preferred embodiment, the straw includes at least one of wheat straw, corn straw and rice straw.

[0017] As a preferred solution, after the fermentation is completed, the process further comprises drying and granulation; the moisture content of the dried straw decomposed organic fertilizer is ≤30%.

[0018] The present invention also provides a straw decomposition organic fertilizer prepared by the preparation method described in the above scheme.

[0019] The present invention also provides the microbial agent described in the above scheme, the straw decomposing organic fertilizer prepared by the preparation method, or the use of the straw decomposing organic fertilizer in returning straw to fields.

[0020] Beneficial effects: The present invention provides a microbial agent for low-temperature degradation of straw, comprising Aspergillus niger spores and Penicillium oxalicum spores; the volume ratio of the Aspergillus niger spores to the Penicillium oxalicum spores is 1-2:1-2; the concentration of the Aspergillus niger spores is 1×10 8 ~9×10 8 CFU / mL; the concentration of the spores of Penicillium oxalicum was 1×10 8 ~9×10 8 CFU / mL. Aspergillus niger and Penicillium oxalicum described in the present invention belong to phosphate-solubilizing fungi, which are acidophilic filamentous fungi that can secrete organic acids (such as oxalic acid, citric acid) and efficient degrading enzymes. They can maintain activity in a low-temperature environment of 4°C, breaking through the temperature limit of traditional microorganisms. The phosphate-solubilizing fungi described in the present invention can accelerate the degradation in straw and destroy its structure by secreting a large amount of organic acids, especially oxalic acid. In addition, the hyphae of the phosphate-solubilizing fungi described in the present invention can penetrate the straw cell wall and secrete fiber lignin degrading enzymes, thereby optimizing the straw decomposition conversion efficiency, effectively reducing the agricultural non-point source pollution load, and promoting the carbon and nitrogen cycle of farmland, ultimately achieving the coordinated development of crop yield improvement and ecological environment protection. The microbial agent described in the present invention can reduce straw burning pollution in autumn and winter, and the released phosphorus can improve soil fertility, realize the integration of "degradation-returning to the field-fertilizing", thereby improving the utilization rate of straw resources under low temperature conditions, reducing the pollution of agricultural solid waste to the environment, and realizing the efficient utilization of straw resources.

[0021] Biological Deposit Description

[0022] Aspergillus niger AH-F-1-2 was deposited in the China General Microorganism Culture Collection (CGMCC) on September 30, 2021, with the deposit number CGMCC No. 23272. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0023] Penicillium oxalicum AH-F-2-7 was deposited in the China General Microorganism Culture Collection (CGMCC) on June 11, 2021, with the deposit number CGMCC No. 22475. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0025] Figure 1The colony images of Aspergillus niger and Penicillium oxalicum; A is the colony image of Aspergillus niger; B is the hyphae image of Aspergillus niger; C is the colony image of Penicillium oxalicum; D is the hyphae image of Penicillium oxalicum;

[0026] Figure 2 This is the straw degradation rate result diagram of each treatment group after 7 days of cultivation in Example 1;

[0027] Figure 3 This is the organic acid result diagram of each treatment group after 7 days of culture in Example 1;

[0028] Figure 4 This is the straw degradation rate result diagram of each treatment group after 7 days of cultivation in Example 2;

[0029] Figure 5 This is the straw degradation rate result diagram of each treatment group after 5 days of cultivation in Example 3;

[0030] Figure 6 This is a product diagram of microbial agent and straw decomposition organic fertilizer; A is microbial agent; B is straw decomposition organic fertilizer;

[0031] Figure 7 This is a graph of soil alkaline nitrogen content in each treatment group in Example 4;

[0032] Figure 8 This is a graph showing the available potassium content in the soil of each treatment group in Example 4;

[0033] Figure 9 This is a graph showing the soil available phosphorus content of each treatment group in Example 4;

[0034] Figure 10 This is a graph showing soil organic matter content in each treatment group in Example 4;

[0035] Figure 11 These are the results of straw decomposition organic fertilizer and straw degradation rate of each treatment after 60 days of cultivation in Example 5; A is straw decomposition organic fertilizer; B is the results of straw degradation rate of each treatment after 60 days of cultivation. DETAILED DESCRIPTION

[0036] The present invention provides a microbial agent for low-temperature degradation of straw, comprising Aspergillus niger spores and Penicillium oxalicum spores; the volume ratio of the Aspergillus niger spores to the Penicillium oxalicum spores is 1-2:1-2;

[0037] The concentration of Aspergillus niger spores is 1×10 8 ~9×10 8 CFU / mL; the concentration of the spores of Penicillium oxalicum was 1×10 8 ~9×108 CFU / mL.

[0038] As an embodiment, the Aspergillus niger includes Aspergillus niger AH-F-1-2, and the preservation number of the Aspergillus niger AH-F-1-2 is CGMCC No.23272; the oxalicum Penicillium includes oxalicum Penicillium AH-F-2-7, and the preservation number of the oxalicum Penicillium AH-F-2-7 is CGMCC No.22475. The Aspergillus niger and the oxalicum Penicillium described in the present invention belong to phosphate-solubilizing fungi, which are acidophilic filamentous fungi that can secrete organic acids (such as oxalic acid, citric acid) and highly efficient degrading enzymes, and can maintain activity in a low-temperature environment of 4°C, breaking through the temperature limit of traditional microorganisms. The phosphate-solubilizing fungi described in the present invention can accelerate the degradation in straw and destroy its structure by secreting a large amount of organic acids, especially oxalic acid. Moreover, the hyphae of the phosphate-solubilizing fungi described in the present invention can penetrate the cell wall of the straw and secrete fiber lignin degrading enzymes, thereby optimizing the decomposition and conversion efficiency of the straw, effectively reducing the agricultural non-point source pollution load, while promoting the carbon and nitrogen cycle of farmland, and ultimately achieving the coordinated development of crop yield improvement and ecological environmental protection.

[0039] The concentration of Aspergillus niger spores of the present invention is 1×10 8 ~9×10 8 CFU / mL; In a specific embodiment of the present invention, the concentration of Aspergillus niger spores can be 1×10 8 ~9×10 8 Any value in CFU / mL, such as 1×10 8 , 2.5×10 8 , 3×10 8 , 4.5×10 8 , 4.5×10 8 , 5×10 8 , 6×10 8 , 6.5×10 8 , 7×10 8 , 8.5×10 8 or 9×10 8 As an embodiment, the method for preparing Aspergillus niger spores comprises: inoculating the Aspergillus niger strain onto potato dextrose agar (PDA) medium, culturing at 28° C. for 5 days to obtain spores; and diluting the spores with 0.85 wt.% sterile saline to obtain the Aspergillus niger spores.

[0040] The concentration of Penicillium oxalicum spores of the present invention is 1×10 8 ~9×10 8 In a specific embodiment of the present invention, the concentration of the spores of Penicillium oxalicum can be 1×10 8 ~9×10 8Any value in CFU / mL, such as 1×10 8 , 2.5×10 8 , 3×10 8 , 4.5×10 8 , 4.5×10 8 , 5×10 8 , 6×10 8 , 6.5×10 8 , 7×10 8 , 8.5×10 8 or 9×10 8 As an embodiment, the method for preparing the spores of Penicillium oxalicum comprises: inoculating the Penicillium oxalicum strain onto potato dextrose agar (PDA) medium, culturing at 28° C. for 5 days to obtain spores; and diluting the spores with 0.85 wt.% sterile saline to obtain the Penicillium oxalicum spores.

[0041] As an embodiment, the microbial agent also includes phosphate and a fertilizer synergist; the phosphate includes at least one of iron phosphate, aluminum phosphate, and tricalcium phosphate; the phosphate of the present invention can serve as an stimulator for the secretion of organic acids by Aspergillus niger and / or Penicillium oxalicum, and can promote Aspergillus niger and / or Penicillium oxalicum to secrete a large amount of organic acid, enhance their metabolic activity, and thus become a booster for Aspergillus niger straw degradation. In addition, during the fermentation process, phosphate reacts with organic acid to form a stable neutral salt, which helps maintain the pH balance of the fermentation system; and promotes the conversion of organic matter into available phosphorus, increasing the soluble phosphorus content in the final product, thereby enhancing the fertilizer efficiency of the microbial organic fertilizer. The present invention does not specifically limit the source of the phosphate. In a specific embodiment of the present invention, the phosphate is purchased from Shanghai Mailin Biochemical Co., Ltd.

[0042] As an embodiment, the fertilizer synergist of the present invention includes at least one of fulvic acid, glutamic acid and alginic acid. The fertilizer synergist of the present invention can buffer the pH change of the culture solution to a certain extent, maintain the efficiency of the enzymatic reaction, and at the same time has a complexing and regulating effect on the intermediate metabolites, which helps to improve the stability and efficiency of the degradation system. Adding a fertilizer synergist can significantly improve the degradation rate of cellulose and hemicellulose in straw by Aspergillus niger and / or Penicillium oxalicum, shorten the early fermentation time, and lay the foundation for subsequent large-scale composting applications. In a small-scale shake flask experiment, by adding a fertilizer synergist to the Aspergillus niger growth system, the culture environment can be effectively optimized, the growth rate of Aspergillus niger mycelium and the activity of cellulase can be increased, thereby accelerating the initial degradation process of straw. The present invention does not specifically limit the source of the fertilizer synergist. In a specific embodiment of the present invention, the fertilizer synergist is purchased from Shanghai Mailin Biochemical Co., Ltd.

[0043] As an embodiment, the amount of phosphate added is 40% to 1000% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores; in a specific embodiment of the present invention, the amount of phosphate added can be any value between 40% and 1000%, such as 40%, 50%, 60%, 80%, 100%, 120%, 150%, 200%, 230%, 250%, 270%, 300%, 350%, 400%, 430%, 450%, 480%, 500%, 550%, 600%, 630%, 680%, 700%, 750%, 800%, 850%, 900%, 950% or 1000%. The amount of phosphate added according to the present invention can synergistically improve fermentation efficiency and nutrient enrichment capacity, ensuring product quality stability.

[0044] As an embodiment, the amount of the fertilizer synergist added is 5% to 50% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores. In a specific embodiment of the present invention, the amount of the fertilizer synergist added can be any value between 5% and 50%, for example, 5%, 6%, 8%, 10%, 12%, 15%, 20%, 23%, 25%, 27%, 30%, 35%, 40%, 43%, 45%, 48% or 50%. The amount of the fertilizer synergist added can promote the degradation of straw. As an embodiment, when the fertilizer synergist is fulvic acid, the amount of fulvic acid added is 10% or 40% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores; when the fertilizer synergist is glutamic acid, the amount of glutamic acid added is 10% to 50% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores, and in a specific embodiment, it can be 10%, 15%, 30%, 35%, 40% or 50%; when the fertilizer synergist is alginic acid, the amount of alginic acid added is 10% or 40% based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores.

[0045] The present invention also provides a method for preparing straw decomposition organic fertilizer, comprising mixing the microbial agent described in the above scheme with a fermentation base material, and fermenting for 15 to 28 days to obtain straw decomposition organic fertilizer;

[0046] The amount of the microbial agent added is 2% to 10% based on the mass of the fermentation base;

[0047] The fermentation base material includes straw and livestock excrement; the mass ratio of the straw to the livestock excrement is 3:7 to 4:6.

[0048] The fermentation base material of the present invention includes straw and livestock manure; the mass ratio of the straw to the livestock manure is 3:7 to 4:6. In a specific embodiment of the present invention, the mass ratio of the straw to the livestock manure can be any ratio between 3:7 and 4:6. Livestock manure has a high nitrogen content. The present invention uses livestock manure as an organic nitrogen source for the fermentation base material, which can quickly activate the growth of the initial bacterial flora. In addition, livestock manure has a relatively high organic matter content, which can improve the substrate stability and maturity in the middle and late stages of fermentation, and can significantly optimize the maturity time and final fertilizer efficiency.

[0049] In one embodiment, the straw comprises at least one of wheat straw, corn straw, and rice straw. In another embodiment, the straw is dried and pulverized to produce pulverized straw; the pulverized straw has a particle size of 2 to 3 cm. The straw of the present invention can promote phosphate-solubilizing fungi to secrete more oxalic acid, thereby lowering the environmental pH and increasing the solubility of insoluble phosphates.

[0050] As an embodiment, the fermentation base material of the present invention further includes auxiliary materials; the auxiliary materials include rice husks and / or sawdust. As an embodiment, the amount of the auxiliary materials added is 10% to 20% based on the total mass of the straw and livestock manure. In the specific embodiment of the present invention, the amount of the auxiliary materials added can be any value between 10% and 20%, such as 10%, 12%, 14.5%, 15%, 17%, 18.5%, 19% or 20%. The auxiliary materials of the present invention can adjust the carbon-nitrogen ratio (C / N) of the fermentation base material, improve the air permeability and water retention of the matrix, contribute to the growth and reproduction of microorganisms and the decomposition of organic matter, and improve the fermentation efficiency and maturity; at the same time, fibrous materials such as sawdust and rice husks can serve as anchorage carriers for microorganisms, enhance their degradation activity, and thus improve the quality and fertilizer efficiency of the final microbial fertilizer.

[0051] As one embodiment, the preparation of the fermentation base includes: mixing the crushed straw, livestock manure and auxiliary materials. As another embodiment, the water content of the fermentation base is 55% to 65%; the carbon-nitrogen ratio of the fermentation base is 25 to 30:1. In a specific embodiment of the present invention, the carbon-nitrogen ratio of the fermentation base can be 25:1, 26:1, 27:1, 28:1, 29:1 or 30:1. The fermentation base of the present invention has superior performance in terms of ingredient ratio, physical and chemical properties and structure, and can effectively meet the growth and metabolic needs of functional microorganisms such as Aspergillus niger. The water content of the present invention is conducive to maintaining microbial activity and providing a suitable moisture environment, which not only prevents anaerobic fermentation, odor and caking caused by excessive moisture, but also avoids excessive dryness that inhibits microbial growth and delays the fermentation process. At the same time, the carbon-nitrogen ratio provides a reasonable ratio of carbon and nitrogen sources for microorganisms, helping to optimize the microbial community structure, promote the rapid growth of aerobic bacteria such as Aspergillus niger, and efficiently degrade organic matter. Furthermore, the carbon-nitrogen ratio of the present invention can also inhibit nitrogen volatilization losses during the fermentation process, improve nitrogen retention, and enhance the fertilizer efficiency of the final product. Therefore, the fermentation base of the present invention has comprehensive advantages such as nutritional balance, reasonable structure, water-gas coordination, high fermentation efficiency, and stable product quality, significantly improving the decomposition speed and application value of microbial organic fertilizers.

[0052] The present invention mixes the microbial agent described in the above scheme with the fermentation base material and ferments for 15 to 28 days to obtain straw decomposition organic fertilizer. Based on the mass of the fermentation base material, the addition amount of the microbial agent is 2% to 10%. In a specific embodiment of the present invention, the addition amount of the microbial agent can be any value in the range of 2% to 10%, such as 2%, 2.5%, 3%, 4%, 5%, 5.1%, 5.5%, 6%, 6.4%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%. As an embodiment, the fermentation temperature is 30 to 65°C. As another embodiment, the maturity judgment criteria of the straw decomposition organic fertilizer include that the material is dark brown, loose in texture, odorless and slightly earthy, the pile temperature drops to ±5°C of the ambient temperature, and the pH value drops from the initial 7 to 8 to 6 to 7.

[0053] As an embodiment, after the fermentation is completed, the method further comprises drying and granulation; the moisture content of the dried straw decomposed organic fertilizer is ≤30%; and the length of the granulated straw decomposed organic fertilizer particles is 2 to 4 cm.

[0054] The present invention also provides straw decomposition organic fertilizer prepared by the preparation method described in the above scheme. As an embodiment, the straw decomposition organic fertilizer has an organic matter content of ≥30%; an effective viable bacteria count of ≥25 million / gram; a pH value of 5.5-8.5; an ascaris egg mortality rate of ≥95%; and a fecal coliform count of ≤100 / gram.

[0055] The present invention also provides the microbial agent described in the above scheme, the straw decomposition organic fertilizer prepared by the preparation method, or the use of the straw decomposition organic fertilizer in returning straw to the field. The present invention does not specifically limit the season for returning straw to the field. The microbial agent and the straw decomposition organic fertilizer described in the present invention can be applied to returning straw to the field in spring, summer, autumn and winter. The straw decomposition organic fertilizer described in the present invention can reduce the pollution caused by straw burning in autumn and winter, and the released phosphorus can improve soil fertility, realizing the integration of "degradation-returning to the field-fertilization", thereby improving the utilization rate of straw resources under low temperature conditions, reducing the pollution of agricultural solid waste to the environment, and realizing the efficient utilization of straw resources.

[0056] In order to further illustrate the present invention, the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] (1) Reagent preparation:

[0059] Montana (PVK) liquid culture medium: 10 g glucose, 0.2 g sodium chloride (NaCl), 0.25 g magnesium sulfate heptahydrate (MgSO4·7H2O), 0.03 g ferric sulfate heptahydrate (FeSO4·7H2O), 0.03 g manganese sulfate tetrahydrate (MnSO4·4H2O), 0.2 g potassium chloride (KCl), 0.5 g ammonium sulfate ((NH4)2SO4), 1 L deionized water, pH 7.0. Sterilize at 121°C for 20 min and set aside.

[0060] PDA culture medium: Wash and peel fresh potatoes, weigh 200 g, cut into small pieces, add water and boil for 30 minutes, filter through eight layers of gauze, add 20 g glucose and 20 g agar powder while hot, stir well, and after the culture medium cools, add deionized water to 1000 mL, the pH value is 7.0.

[0061] (2) Straw sample processing

[0062] Fresh corn and wheat straw were collected from the Anhui Agricultural University's Suzhou Wanbei Experimental Station (33°41′N, 117°5′E). The straw was oven-dried at 105°C for 30 min and then dried at 65°C to a constant weight. The dried corn and wheat straw were then cut into 2 cm segments, resulting in corn straw and millet straw, which were then used as standby materials.

[0063] (3) Preparation of spore suspension

[0064] The Aspergillus niger (CGMCC No. 23272) used in this experiment was isolated from the rhizosphere soil of corn in Suzhou, Anhui Province. The Penicillium oxalicum (CGMCC No. 22475) used in this experiment was isolated from the rhizosphere soil of corn in Suzhou, Anhui Province.

[0065] Aspergillus niger and Penicillium oxalicum were inoculated into potato dextrose agar (PDA) medium and cultured at 28℃. Figure 1 After 5 days of culture, spores were collected by washing with sterile water. After filtering through three layers of sterile gauze to remove mycelial fragments, the spore concentration was determined using a hemocytometer and adjusted to 1×10 8 CFU / mL, and obtain the Aspergillus niger spore suspension and Penicillium oxalicum spore suspension.

[0066] (4) Sample collection and analysis

[0067] Group processing:

[0068] Corn straw group (MS): Add 100 mL of sterilized PVK medium and 0.5 g of corn straw into a 250 mL conical flask.

[0069] Wheat straw group (WS): 100 mL of sterilized PVK medium and 0.5 g of wheat straw were added to a 250 mL conical flask.

[0070] Aspergillus niger + corn straw group (ANG+MS): 100 mL of sterilized PVK medium and 0.5 g of corn straw were added to a 250 mL conical flask; then 1 mL of Aspergillus niger spore suspension was inoculated.

[0071] Aspergillus niger + wheat straw group (ANG+WS): 100 mL of sterilized PVK medium and 0.5 g of wheat straw were added to a 250 mL conical flask; then 1 mL of Aspergillus niger spore suspension was inoculated.

[0072] Penicillium oxalicum + corn straw group (POX+MS): 100 mL of sterilized PVK medium and 0.5 g of corn straw were added to a 250 mL conical flask; then 1 mL of Penicillium oxalicum spore suspension was inoculated.

[0073] Penicillium oxalicum + wheat straw group (POX+WS): 100 mL of sterilized PVK medium and 0.5 g of wheat straw were added to a 250 mL conical flask; then 1 mL of Penicillium oxalicum spore suspension was inoculated.

[0074] Each group used a sealing film containing a 0.22 μm breathable film (BS-QM-003, Biosharp) to seal the bottle mouth; this experiment was a destructive sampling, and 3 replicates were set for each treatment.

[0075] The culture conditions were set at 4°C, 15°C, and 28°C, and the culture was shaken at 180 rpm for 7 days. After the culture, the PVK culture medium was filtered using a 0.22 μm polyethersulfone filter membrane. The straw was repeatedly rinsed with sterile water until the surface was clean. The straw was dried at 60°C to a constant weight and the straw mass was measured. The straw degradation rate was calculated according to Formula I. The results are shown in Tables 1 and Figure 2 .

[0076] Straw degradation rate: R wst / mst =(M0-M t ) / M0×100%Ⅰ;

[0077] Where R wst / mst is the straw degradation rate (%); M0 is the initial mass of straw before degradation (g); M t is the mass of straw after degradation td (g); t is the degradation time (d).

[0078] Table 1 Straw degradation rate in different treatment groups (%)

[0079] temperature MS WS POX+MS POX+WS ANG+MS ANG+WS 4℃ 10.65±0.07c 4.87±0.07a 14.46±0.74b 11.36±1.41c 15.72±0.99c 11.27±0.49c 15℃ 12.45±0.07b 5.21±0.40a 21.22±1.05a 14.18±0.40b 21.63±0.64b 15.09±1.20b 28℃ 14.64±0.05a 5.96±0.42a 22.63±1.71a 17.03±0.41a 24.67±1.41a 18.13±0.33a

[0080] Note: a, b, and c in Table 1 indicate significant differences among treatments (p<0.05). The same applies to the following tables and figures.

[0081] From Table 1 and Figure 2Without the addition of phosphate-solubilizing fungi (Aspergillus niger or Penicillium oxalicum), the degradation rates of wheat and corn straw at 4°C, 15°C, and 28°C after 7 days of incubation were (4.87%, 10.65%), (5.21%, 12.45%), and (5.96%, 14.64%), respectively. However, with the addition of Penicillium oxalicum, the degradation rates of wheat and corn straw were (11.36%, 14.46%), (14.18%, 21.22%), and (17.03%, 22.63%), respectively. The researchers also found that at room temperature (28°C), Aspergillus niger exhibited the highest degradation rates for wheat and corn straw, reaching 18.13% and 24.67%, respectively. At 15°C, the degradation rates decreased to 15.09% and 21.63%, respectively. At 4°C, Aspergillus niger maintained its degradation efficiency, reaching 11.27% and 15.72%, respectively. Both Aspergillus niger and Penicillium oxalicum significantly promoted straw degradation, with Aspergillus niger exhibiting a greater ability to degrade straw than Penicillium oxalicum. The results indicate that Aspergillus niger and Penicillium oxalicum are the dominant strains for wheat and corn degradation, maintaining their ability to degrade straw at low temperatures. Compared to the absence of Aspergillus niger and Penicillium oxalicum, the addition of Aspergillus niger and Penicillium oxalicum increased straw degradation rates by 5.07% to 12.17% and 3.81% to 11.07%, respectively, at different temperatures.

[0082] HPLC was used to analyze the types and contents of organic acids secreted by Aspergillus niger and Penicillium oxalicum. The results are shown in Table 2 and Figure 3 .

[0083] Table 2 Oxalic acid content in culture medium of different treatment groups (mg / L)

[0084]

[0085]

[0086] According to Table 2 and Figure 3Without the addition of phosphate-solubilizing fungi (Aspergillus niger or Penicillium oxalicum), the oxalic acid contents in the corn straw and wheat straw solutions at 4°C after 7 days of incubation were 15.123 mg / L and 43.441 mg / L, respectively. Notably, the oxalic acid content in the corn straw treatment reached its highest level after the addition of Aspergillus niger, reaching 394.608 mg / L, while the Penicillium oxalicum content reached 301.745 mg / L at the same time, demonstrating a significant increase in oxalic acid content. Furthermore, the oxalic acid content in the ANG+MS treatment (1097.820 mg / L) at 4°C was 2.78 times lower than that in the 28°C treatment, and the oxalic acid content in the POX+MS treatment (909.250 mg / L) was 3.01 times lower than that in the 28°C treatment, consistent with the aforementioned straw degradation trends. Oxalic acid has a high acidity constant (pKa = 1.27), which can effectively lower the environmental pH and increase the solubility of insoluble phosphates, thus having a significant effect on the degradation of straw. At the same time, the addition of straw also promotes phosphate-degrading fungi to secrete more oxalic acid.

[0087] Example 2

[0088] Effects of phosphate-solubilizing fungi on promoting straw degradation

[0089] (1) Sample preparation

[0090] Phosphates include iron phosphate (FePO4·2H2O, denoted as Fe-P), aluminum phosphate (AlPO4, denoted as Al-P) and tricalcium phosphate (Ca3(PO4)2, denoted as Ca-P), all of which were purchased from Shanghai Mailin Biochemical Co., Ltd.

[0091] (2) Preparation of corn stalks: The operation is the same as step (2) of Example 1.

[0092] (3) Preparation of spore suspension: The operation is the same as step (3) of Example 1.

[0093] (4) Sample collection and analysis

[0094] Group processing:

[0095] Corn straw group (MS): 100 mL of PVK liquid medium and 0.5 g of corn straw were added to a 250 mL conical flask.

[0096] Phosphate-solubilizing fungi + corn straw (PSF+MS): Add 100 mL of PVK liquid medium and 0.5 g of corn straw into a 250 mL conical flask, and add 1 mL each of Aspergillus niger spore suspension and Penicillium oxalicum spore suspension.

[0097] Ferric phosphate + phosphate-solubilizing fungi + corn straw (Fe-P + PSF + AMS): Add 100 mL of PVK liquid medium into a 250 mL conical flask, add 0.5 g of Fe-P as the initial phosphorus source, adjust the pH to 6.5, add 0.5 g of corn straw, and 1 mL each of Aspergillus niger spore suspension and Penicillium oxalicum spore suspension.

[0098] Aluminum phosphate + phosphate-solubilizing fungi + corn straw (Al-P + PSF + AMS): Add 100 mL of PVK liquid medium into a 250 mL conical flask, add 0.5 g of Al-P as the initial phosphorus source, adjust the pH to 6.5, add 0.5 g of corn straw, and 1 mL each of Aspergillus niger spore suspension and Penicillium oxalicum spore suspension.

[0099] Calcium phosphate + phosphate-solubilizing fungi + corn straw (Ca-P + PSF + AMS): Add 100 mL of PVK liquid medium to a 250 mL conical flask, add 0.5 g of Ca-P as the initial phosphorus source, adjust the pH to 6.5, add 0.5 g of corn straw, and 1 mL each of Aspergillus niger spore suspension and Penicillium oxalicum spore suspension.

[0100] Each treatment group used a 0.22 μm breathable film to seal the bottle mouth, and then cultured in a shaking incubator at 28°C and 180 rpm for 7, 14, 21, and 30 days, respectively.

[0101] This experiment was a destructive sampling experiment, divided into 4 periods, with 3 replicates for each treatment. Samples were taken on the 7th, 14th, 21st, and 30th days of incubation in a shaker. After incubation, the straw was repeatedly rinsed with sterile water until the surface was clean, and then dried at 45°C to a constant weight, and the straw mass was measured. The corn straw degradation rate was determined in the same way as in Example 1. The results are shown in Tables 3 and Figure 4 .

[0102] Table 3 Straw degradation rate in different treatment groups (%)

[0103] time MS PSF+MS Fe-P+PSF+MS Ca-P+PSF+MS Al-P+PSF+MS 7d 14.35±0.28c 19.50±0.87b 37.49±1.43a 37.59±0.81a 33.13±4.14a 14d 15.67±1.15c 27.01±1.00b 38.07±2.11a 38.33±1.26a 35.00±1.32a 21d 19.17±1.89c 29.33±2.52b 39.34±3.26a 39.51±1.38a 35.50±2.65a 28d 21.02±0.50c 33.00±1.00b 45.83±3.33a 39.67±3.01a 43.83±1.15a

[0104] From Table 3 and Figure 4After 7 days of incubation, the degradation rates of corn straw in the presence of Fe-P, Ca-P, and Al-P were 37.49%, 37.59%, and 33.13%, respectively. The study found that phosphate significantly promoted the degradation of straw by phosphate-solubilizing fungi. Compared to the degradation rate of 19.5% in the treatment with the addition of bacteria alone, the straw degradation rate increased 2.0-fold after 7 days of incubation at 28°C. Furthermore, the straw degradation rate continued to increase slowly over the following 14, 21, and 28 days. Compared to the absence of phosphate, the increase in the straw degradation rate by phosphate-solubilizing fungi ranged from 6.17% to 18.09% between 14 and 28 days. These results indicate that phosphate significantly promotes straw degradation.

[0105] Example 3

[0106] Effects of phosphate-solubilizing fungi compound fertilizer synergist on promoting straw degradation

[0107] (1) Sample preparation

[0108] Fertilizer synergists including fulvic acid, glutamic acid, and alginic acid were purchased from Shanghai Mailin Biochemical Co., Ltd.

[0109] (2) Preparation of rice straw: The fresh rice straw used was collected from the Wanzhong Experimental Station of Anhui Agricultural University, and the operation was the same as step (2) of Example 1.

[0110] (3) Preparation of spore suspension: The operation is the same as step (3) of Example 1.

[0111] (4) Sample collection and analysis

[0112] Group processing

[0113] Fulvic acid group: 100 mL of PVK liquid medium was added to a 250 mL conical flask, and fulvic acid (0 g, 0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g) was added respectively. The pH was adjusted to 6.5, and 0.5 g of corn straw, 0.5 mL of Aspergillus niger spore suspension and 0.5 mL of Penicillium oxalicum spore suspension were added.

[0114] Glutamic acid group: 100 mL of PVK liquid medium was added to a 250 mL conical flask, and glutamic acid (0 g, 0.1 g, 0.2 g, 0.3 g, 0.4 g, and 0.5 g) was added respectively. The pH was adjusted to 6.5, and 0.5 g of corn straw, 0.5 mL of Aspergillus niger spore suspension, and 0.5 mL of Penicillium oxalicum spore suspension were added.

[0115] Alginate group: 100 mL of PVK liquid medium was added to a 250 mL conical flask, and alginic acid (0 g, 0.1 g, 0.2 g, 0.3 g, 0.4 g, and 0.5 g) was added respectively. The pH was adjusted to 6.5, and 0.5 g of corn straw, 0.5 mL of Aspergillus niger spore suspension, and 0.5 mL of Penicillium oxalicum spore suspension were added.

[0116] Each treatment group used a 0.22 μm breathable film to seal the bottle mouth, and after sealing, the bottle was cultured in a shaking incubator at 28°C and 180 rpm. The culture time was set to 5 days. The rice straw degradation rate was determined by the same method as in Example 1. The results are shown in Tables 4 and Figure 5 .

[0117] Table 4 Straw degradation rate in different treatment groups (%)

[0118] Group Fulvic acid glutamate alginic acid 0.0g 13.83±2.33a 13.83±2.33a 13.83±2.33a 0.1g 18.69±1.60b 22.72±0.11a 18.37±1.26b 0.2g 10.60±0.57a 12.12±3.25a 14.05±2.87a 0.3g 3.92±0.65b 19.60±1.50a 6.71±3.13b 0.4g 16.44±0.20a 16.61±0.44a 15.69±0.44a 0.5g 4.85±1.09b 14.21±3.89a 3.89±0.16b

[0119] From Table 4 and Figure 5 The results show that after 5 days of incubation with different fertilizer synergists and a mixed spore suspension of phosphate-solubilizing fungi, the rice straw degradation rate reached the highest levels when 0.1g of fulvic acid, glutamic acid, and alginic acid were added, reaching 18.69%, 22.72%, and 18.37%, respectively. Furthermore, the study found that glutamic acid significantly promoted the degradation of straw by phosphate-solubilizing fungi. Compared with the degradation rate of 13.83% in the treatment with bacteria alone, the straw degradation rate increased by 5.77% after 5 days of incubation at 28°C with the addition of 0.3g of glutamic acid. Furthermore, fulvic acid and alginic acid at 0.1g and 0.4g levels enhanced the efficiency of straw degradation by phosphate-solubilizing fungi. These results indicate that different fertilizer synergists have different effects on the degradation of wheat straw by phosphate-solubilizing fungi, and that the addition of appropriate amounts of glutamic acid, fulvic acid, and alginic acid significantly enhances the potential of phosphate-solubilizing fungi to degrade straw.

[0120] Example 4

[0121] Creation of organic fertilizer from straw decomposition

[0122] (1) Prepare the fermentation base: Mix straw (corn straw, wheat straw, and rice straw in a mass ratio of 3:2:1) and livestock and poultry manure (pig manure and chicken manure in a mass ratio of 2:1) in a mass ratio of 4:6 as the main raw material, and use rice husks, sawdust, etc. as auxiliary materials. The mass ratio of the main raw material to the auxiliary material is 8:1. Each raw material should be free of obvious impurities and the moisture content should be controlled at 50% to 60%. The raw materials should be crushed to a particle size of ≤5 cm and mixed in proportion to adjust the carbon-nitrogen ratio to 25:1.

[0123] (2) Inoculation: Based on the weight of the fermentation base, 0.25% of Aspergillus niger spore suspension, 0.25% of Penicillium oxalicum spore suspension, 5% of ferric phosphate and 1‰ of glutamic acid were mixed to prepare a microbial agent for low-temperature degradation of straw (referred to as straw fast-rot agent), such as Figure 6 As shown in A, the above microbial agent is mixed with the fermentation base material and fermented. The amount of the microbial agent added is 5.1% based on the mass of the fermentation base material.

[0124] (3) Fermentation: Aerobic composting is used during the fermentation phase. The compost is 2.5 m wide and 1.3 m high. Oxygen is supplied by regular turning of the compost, and the temperature is controlled at 55-65°C. The total fermentation time is approximately 28 days. The criteria for composting maturity include dark brown, loose texture, no odor, and a slight earthy aroma. The compost temperature has dropped to ±5°C below ambient temperature, and the pH has dropped from an initial 7-8 to 6-7.

[0125] (4) Post-processing: In the post-processing stage, the material needs to be dried to a moisture content of ≤30%; after drying, it is granulated by extrusion to a particle length of 2 to 4 cm, and finally sealed in a breathable woven bag or plastic bag and stored in a cool and dry place to obtain straw decomposition organic fertilizer (referred to as straw fast-rotting microbial organic fertilizer), such as Figure 6 As shown in B, the shelf life of the obtained straw decomposition organic fertilizer is 6 to 12 months.

[0126] (5) Quality control: The straw decomposition organic fertilizer in step (4) must comply with the national standard NY 884-2012, see Table 5. The straw decomposition organic fertilizer includes organic matter content ≥30%, effective viable bacteria count ≥25 million / g, pH value 5.5-8.5, ascaris egg mortality rate ≥95%, and fecal coliform count ≤100 / g.

[0127] Table 5 Formula of winter straw fast-rotting biological organic fertilizer with phosphate-solubilizing fungi

[0128]

[0129] Example 5

[0130] Straw decomposition organic fertilizer for returning straw to fields

[0131] (1) Straw sample processing: Corn straw was taken from the Anhui Agricultural University's northern Anhui experimental field. The corn straw was cut into 1-2 cm long straw segments. 20.00 g of fresh corn straw was weighed, and the moisture content of the straw was measured. The straw was placed in a 100-mesh nylon mesh bag and set aside.

[0132] (2) The test soil type is sandy ginger black soil. The basic physical and chemical properties of the soil are shown in Table 6.

[0133] Table 6 Basic properties of the tested soil

[0134] pH Available phosphorus (mg / kg) Fast-acting potassium (mg / kg) Alkaline nitrogen (mg / kg) Organic matter (g / kg) 8.38 34.58 347.18 101.85 26.88

[0135] (3) Processing:

[0136] The experiment was carried out in the experimental field of Anhui Agricultural University Suzhou Wanbei Experimental Station (33°41′N, 117°5′E). The experimental months were from November to January, with temperatures ranging from -1°C to 8°C. The sampling time points were 1 week, 2 weeks, 1 month, and 2 months.

[0137] Straw decomposition organic fertilizer group (PSF): add 15kg straw decomposition organic fertilizer (such as Figure 11 After that, 20.00 g of straw from step (1) was quickly buried in the soil of the experimental field.

[0138] Control group (CK): The treatment method was the same as that of the PSF group, except that no straw decomposed organic fertilizer was added.

[0139] At each sampling time point, two rows of six replicate bags containing straw and two blank bags without straw were set up, for a total of four sampling time points. Each sampling time point consisted of three bags containing straw and one bag without straw, for a total of eight bags (3 bags + 1 empty bag) × 2 rows. For the four sampling time points, 4 × 8 = 32 bags were used, and for the two treatments, 32 × 2 = 64 bags were used, for a total of 64 bags. The blank bag served as a control to eliminate interference from other factors.

[0140] (4) The physical and chemical properties of soil and straw degradation rate of different groups were measured at the sampling time.

[0141] A. Determination of soil physical and chemical properties: Determination of the available nutrient content in the chemical properties of soil samples, including soil organic matter (SOM), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK) and pH. The specific determination methods are shown in Table 7. The determination results are shown in Table 8 and Figures 7 to 10 shown.

[0142] Table 7 Soil index detection method

[0143] index method organic matter Potassium dichromate-external heating method pH Water-soil ratio 1 / 2.5 pH meter Fast-acting potassium Ethyl ammonium acetate extraction-flame photometry Available phosphorus Sodium bicarbonate extraction-molybdenum antimony colorimetric method Alkaline nitrogen Alkaline diffusion method

[0144] Table 8 Test results of soil physical and chemical properties of each treatment group

[0145]

[0146] From Table 8 and Figures 7 to 10 It can be seen that returning straw to the field and applying microbial organic fertilizer is an effective measure to restore soil nutrient balance and ensure long-term utilization of cultivated land. Figures 7 to 10 The results show the changes in soil nutrients. Straw return plays an important role in supplementing soil organic carbon and increasing soil nutrient elements. Figure 10Analysis showed that there were significant differences in soil organic matter at 7d and 60d of decomposition. Compared with the control group, the organic matter content in the soil of the treatment group increased by 0.13mg / kg, 2.47mg / kg, 3.62mg / kg and 3.85mg / kg at 7, 14, 30 and 60d respectively. At 60d, compared with CK, the soil organic matter content increased the most in the treatment with microbial organic fertilizer, which was 3.85mg / kg, which played a certain role in promoting the accumulation of soil organic matter. At the 60th day of decomposition, the available phosphorus content in the soil of the treatment group and the control group were 46.36mg / kg and 43.64mg / kg respectively. Compared with the available phosphorus content in the soil on the 7th day, the control group increased by 2.43mg / kg, and the treatment group increased by nearly 5.47mg / kg ( Figure 9 There was no significant difference in the content of available potassium in the early stage of decomposition, but a significant difference in the late stage. It can be seen that the release of available potassium is mainly concentrated in the late stage of decomposition. Among them, on the 60th day, the content of available potassium in the treatment group increased by 25.04% compared with the control group ( Figure 8 In the early stage of decomposition, the alkaline nitrogen content of the treatment group was 7.00 mg / kg lower than that of the control group. However, on the 14th day, the treatment group had a certain accumulation, which was 26.81 mg / kg higher than that of the control group. It decreased again in the late stage of decomposition. This may be due to the "microbial nitrogen digging effect". After a large amount of crop straw is returned to the field, soil microorganisms will absorb soil nitrogen nutrients, which will affect the effective decomposition of the returned crop straw ( Figure 7 In summary, in the treatment group, with the proliferation and reproduction of microorganisms, more straw nutrients were released, and straw decomposition organic fertilizer had a significant promoting effect on the release of soil nutrients under low temperature conditions in winter.

[0147] B. At different sampling times, the nylon mesh bags containing straw were taken out and the straw degradation rate was measured in the same manner as in Example 1. The test results are shown in Tables 9 and Figure 11 As shown in B.

[0148] Table 9 Straw degradation rate of each treatment group (%)

[0149] 7d 14d 30d 60d CK 17.95±0.91a 19.38±1.75b 25.03±1.16b 27.39±1.82b PSF 13.79±2.14b 24.16±1.49a 30.57±1.21a 33.17±2.29a

[0150] According to Table 9 and Figure 11It can be seen that the microbial agent of the present invention can significantly promote straw degradation in winter. Among them, the straw degradation rate of the treatment group remained the highest at 33.17% after 60 days, and the degradation growth rate increased by 21.11% compared with the control group. At the same time, the degradation growth rate of the treatment group increased by 140.5% between the 7th and 60th days, which was 2.67 times faster than the straw degradation growth rate of the control group between 7 and 60 days. This shows that the phosphate-solubilizing fungi winter straw fast-decomposing biological organic fertilizer still maintains a high growth rate under low temperature conditions in the later period, and has significant straw degradation potential. This shows that phosphate-solubilizing fungi have a significant effect on promoting straw decomposition, and in the long run, applying straw-decomposing organic fertilizer when returning straw to the field has a good effect on promoting decomposition.

[0151] In summary, the phosphate-solubilizing fungi (Aspergillus niger and Penicillium oxalicum) in the microbial agent of the present invention have the ability to produce oxalic acid, a wide enzyme spectrum, and cold-resistant characteristics. At the same time, the addition of phosphate / fertilizer synergists can promote the decomposition of straw and increase the cellulose degradation rate. Straw decomposition organic fertilizer can promote nutrient release, increase soil organic matter and available phosphorus content, achieve synergistic efficiency of straw resource utilization and soil improvement, and provide an innovative solution for the green treatment of agricultural waste and sustainable agricultural development in winter.

[0152] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A microbial agent for low-temperature degradation of straw, characterized in that: The method comprises spores of Aspergillus niger and spores of Penicillium oxalicum; the volume ratio of the spores of Aspergillus niger to the spores of Penicillium oxalicum is 1-2:1-2; The concentration of Aspergillus niger spores is 1×10 8 ~9×10 8 CFU / mL; the concentration of the spores of Penicillium oxalicum was 1×10 8 ~9×10 8 CFU / mL.

2. The microbial agent according to claim 1, characterized in that The Aspergillus niger includes Aspergillus niger AH-F-1-2, and the preservation number of the Aspergillus niger AH-F-1-2 is CGMCC No. 23272; the Penicillium oxalicum includes Penicillium oxalicum AH-F-2-7, and the preservation number of the Penicillium oxalicum AH-F-2-7 is CGMCC No. 22475.

3. The microbial agent according to claim 1 or 2, characterized in that The microbial agent also includes phosphate and fertilizer synergist; The phosphate includes at least one of iron phosphate, aluminum phosphate and tricalcium phosphate; The fertilizer synergist includes at least one of fulvic acid, glutamic acid and alginic acid.

4. The microbial agent according to claim 3, characterized in that Based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores, the added amount of the phosphate is 40% to 1000%; based on the total mass of the Aspergillus niger spores and the Penicillium oxalicum spores, the added amount of the fertilizer synergist is 5% to 50%.

5. A method for preparing straw decomposition organic fertilizer, characterized in that: The method comprises mixing the microbial agent according to any one of claims 1 to 4 with a fermentation base material, and fermenting for 15 to 28 days to obtain straw decomposition organic fertilizer; The amount of the microbial agent added is 2% to 10% based on the mass of the fermentation base; The fermentation base material includes straw and livestock excrement; the mass ratio of the straw to the livestock excrement is 3:7 to 4:

6.

6. The preparation method according to claim 5, characterized in that The water content of the fermentation base is 55% to 65%; the carbon-nitrogen ratio of the fermentation base is 25 to 30:1; and the fermentation temperature is 30 to 65°C.

7. The preparation method according to claim 5, characterized in that The straw includes at least one of wheat straw, corn straw and rice straw.

8. The preparation method according to claim 5, characterized in that After the fermentation is completed, the process further includes drying and granulation; the moisture content of the dried straw decomposed organic fertilizer is ≤30%.

9. Straw decomposition organic fertilizer prepared by the preparation method according to any one of claims 5 to 8.

10. Use of the microbial agent according to any one of claims 1 to 4, the straw decomposition organic fertilizer prepared by the preparation method according to any one of claims 5 to 8, or the straw decomposition organic fertilizer according to claim 9 in returning straw to fields.

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