Low-temperature rotting-promoting composite microbial inoculant, straw in-situ efficient returning method and application

Abstract

The application discloses a low-temperature rotting-promoting composite microbial inoculum, a high-efficiency in-situ straw returning method and application, and belongs to the technical field of microbial inoculums. The low-temperature rotting-promoting composite microbial inoculum comprises Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella covesi zqw90, Weissella paramesenteroides zqw26 and Neurospora crassa N7, and the mass ratio of the viable bacterial numbers of the Stenotrophomonas maltophilia JGDQ29-2, the Bacillus JX-7, the Weissella covesi zqw90, the Weissella paramesenteroides zqw26 and the Neurospora crassa N7 is 1-2:1-2:1-2:1.5-2:2.5-3. The application realizes the synchronous high-efficiency degradation of each component of the straw, improves the overall rotting efficiency and improves the soil nutrient components by screening high-efficiency cellulose, hemicellulose and lignin degradation strains and constructing a composite microbial system with multiple bacteria symbiosis and function complementation.

Description

Technical Field

[0001] This invention belongs to the field of microbial preparation technology, specifically relating to a low-temperature decomposition-promoting compound microbial agent, a method for efficient in-situ straw return to the field, and its applications. Background Technology

[0002] Returning straw to the field is a key measure to increase soil organic matter, improve soil physical and chemical properties, reduce fertilizer application, and achieve green and sustainable agricultural development. However, problems such as slow natural decomposition rate of straw, poor quality of straw return, and insignificant yield increase for current crops have long hindered the promotion and application of straw return technology. Especially in cold northern regions such as Northeast China and Inner Mongolia, the low temperature environment significantly inhibits microbial activity, resulting in a natural decomposition cycle of straw lasting two to three years or even longer, which seriously restricts the normal growth of subsequent crops. In the return of straw to dryland crops, "the operation is cumbersome, and many return methods require many processing steps such as centralized collection, mixing, composting, watering, and turning, which is labor-intensive and time-consuming, and farmers are unwilling to adopt them." Under flooded conditions in paddy fields, the anaerobic decomposition of straw also significantly increases methane emissions, causing the carbon sequestration benefits of straw return to the field to be offset by increased greenhouse gas emissions, creating a contradiction between carbon sequestration and emission reduction.

[0003] In the field of microbial inoculants, some decomposition-promoting microbial agents have been applied to agricultural production. However, most agents suffer from poor low-temperature adaptability, insufficient synergy among microbial strains, and unstable degradation efficiency, making it difficult to meet the actual needs of the low-temperature climate zone in Northeast China and different types of farmland crops. Furthermore, microbial inoculants represent a green and efficient cutting-edge technology for saline-alkali land management. Utilizing the specific functions of microorganisms in compound inoculants, as well as the synergistic effects between different microorganisms, the soil environment can be fundamentally improved. For example, extracellular secretions produced by microbial metabolism can complex with salt ions in the soil, and metabolic organic acids can neutralize the high pH of saline-alkali land, increasing the content of effectively dissolved phosphorus or potassium. However, the systematic research and industrial application of highly efficient compound inoculants are still immature, especially the straw return technology for saline-alkali land, which is still in its early stages. Summary of the Invention

[0004] To address the aforementioned shortcomings in the existing technology, this invention provides a low-temperature decomposition-promoting compound microbial agent, a method for efficient in-situ straw return to the field, and its applications.

[0005] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: The purpose of this invention is to provide a low-temperature composting compound microbial agent, which includes Stenotrophomonas maltophilia (Stereotrophozoites) with a live bacteria count-to-mass ratio of 1~2:1~2:1~2:1.5~2:2.5~3. Stenotrophomonas maltophilia JGDQ29-2, Bacillus ( Bacillus sp.) JX-7, Weissella esculenta (sp.) JX-7, Weissella esculenta ( Weissella cibaria zqw90, Enterobacter sieboldii ( Weissella cibaria zqw26 and Neurospora crassa ( Neurospora crassa )N7.

[0006] Furthermore, the viable count ratio of Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella maltophilia zqw90, Weissella enterica zqw26, and Neurospora crassa N7 was 1.5~2:1.5~2:1.5~2:1.5~2:3.

[0007] Furthermore, Stenotrophomonas maltophilia JGDQ29-2 was deposited at the China General Microbiological Culture Collection Center on July 24, 2023, with accession number CGMCC No. 27979; Bacillus JX-7 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on July 24, 2023, with accession number CGMCC No. 27978; Weissella esculenta zqw90 was deposited at the China General Microbiological Culture Collection Center on June 21, 2022, with accession number CGMCC No. 25149; Enterobacter vesiculosus zqw26 was deposited at the China General Microbiological Culture Collection Center on June 21, 2022, with accession number CGMCC No. 25137; Neurospora crassa N7 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on July 24, 2023, with accession number CGMCC No. 40738.

[0008] Furthermore, the total effective viable count of the low-temperature composting compound microbial agent is ≥1.0×10⁻⁶. 9 CFU / g.

[0009] Another objective of this invention is to provide a method for preparing the above-mentioned low-temperature decomposition-promoting compound microbial agent, wherein each strain is inoculated into a culture medium for cultivation, seed liquid is harvested, and then the seed liquids of each strain are mixed in proportion to obtain the low-temperature decomposition-promoting compound microbial agent.

[0010] Furthermore, Stenotrophomonas maltophilia JGDQ29-2 and Bacillus JX-7 were inoculated into LB solid medium and cultured aerobically with shaking at 30-35°C for 34-40 h. Weissella esculenta zqw90 was inoculated into MRS liquid medium and incubated statically at 30-35°C for 34-40 h; Enterobacter vesiculosus zqw26 was inoculated into MRS liquid medium and cultured in a facultative anaerobic shaking culture at 30-35℃ for 46-50 h; Neurospora crassa N7 was inoculated into straw-inorganic salt medium and cultured aerobically with shaking at 24-28℃ for 92-100 h.

[0011] Another objective of this invention is to provide a method for efficient in-situ straw return to the field, as detailed below: In-situ high-efficiency return of corn straw to the field in dryland: corn mechanical harvesting and straw crushing → application of microbial agents → deep loosening followed by high-speed harrowing and mixing of straw into the field → ridging / flat planting for corn sowing and fertilization → chemical weeding and pest and disease control → inter-row cultivation management → corn harvesting at maturity.

[0012] In-situ high-efficiency rice straw return technology: mechanical harvesting and straw crushing of rice → one-turn-rotary tillage for oxygenation → shallow water soaking of the field → application of microbial agents → slurry return to the field → sowing of the next crop and supporting management → harvesting of rice at maturity.

[0013] Another object of the present invention is to provide the use of the above-mentioned low-temperature decomposition-promoting compound microbial agent in the improvement of saline-alkali land.

[0014] Another object of the present invention is to provide the use of the above-mentioned low-temperature composting compound microbial agent in the preparation of formulations for improving saline-alkali land.

[0015] Another object of the present invention is to provide the use of the above-mentioned low-temperature decomposition-promoting compound microbial agent or the preparation described in claim 8 in increasing crop yield.

[0016] Furthermore, the crops are corn, soybeans, or rice.

[0017] The beneficial effects of this invention are: Firstly, it addresses the challenge of low-temperature straw decomposition in cold regions. In response to the long winters and 0-15℃ temperatures in northern cold regions, this invention develops a compound microbial agent that remains highly active even at low temperatures. This overcomes the inhibition of microbial metabolic activity caused by low temperatures, significantly shortening the straw decomposition cycle from traditional methods to completion within the current season, ensuring no impact on the normal production of subsequent crops.

[0018] Secondly, there is the problem of insufficient synergistic function among microbial strains. Existing microbial agents mostly adopt single-strain or simple compound formulations, which limit their degradation capacity. This invention systematically screens highly efficient cellulose, hemicellulose, and lignin-degrading strains to construct a multi-strain synergistic and functionally complementary composite microbial system, achieving simultaneous and efficient degradation of various components of straw, improving overall decomposition efficiency, and improving soil nutrient composition.

[0019] Third, the technology of returning microbial agents to the field lacks a systematic approach. Existing technologies mostly focus on the formulation of microbial agents themselves, lacking consideration of field application processes, and suffer from complex operation and high promotion costs. This invention simplifies the process of returning microbial agents to the field, achieving a simplified agronomic operation of "one-time operation, full amount returned to the field," reducing the threshold for farmers to use and economic costs, and improving the accessibility and feasibility of technology promotion. Attached Figure Description

[0020] Figure 1 This is a graph showing the results of the antagonism test between bacterial strains; Figure 2 Field application photos of a low-temperature composting compound microbial agent used for in-situ straw return to the field. Detailed Implementation

[0021] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0022] Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia JGDQ29-2, with accession number CGMCC No. 27979, was deposited at the China General Microbiological Culture Collection Center on July 24, 2023, and has been disclosed in the invention patent application with application number CN202411674934.3.

[0023] Weissella esculenta ( Weissella cibaria zqw90, with accession number CGMCC No. 25149, was deposited at the China General Microbiological Culture Collection Center on June 21, 2022. It has been disclosed in the invention patent application with application number CN202310812620.4.

[0024] Neurospora crassa ( Neurospora crassa N7, with accession number CGMCC No.40738, was deposited at the China General Microbiological Culture Collection Center on July 24, 2023, and has been disclosed in the invention patent application with application number CN202411675478.4.

[0025] Enterobacter vesiculosus ( Weissella cibaria The strain zqw26, with accession number CGMCC No. 25137, was deposited at the China General Microbiological Culture Collection Center on June 21, 2022.

[0026] Bacillus ( Bacillus sp. The strain JX-7, with accession number CGMCC No. 27978, was deposited on July 24, 2023, at the China General Microbiological Culture Collection Center. It has been disclosed in invention patent application CN202411675532.5.

[0027] Example 1 A low-temperature composting compound microbial agent with a total effective viable count of 6.0 × 10⁻⁶. 9 CFU / g, including Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella tamariscina zqw90, Weissella enterica zqw26 and Neurospora crassa N7.

[0028] Its preparation method is as follows: (1) Stenotrophomonas maltophilia JGDQ29-2 and Bacillus JX-7 were inoculated into LB solid medium and cultured at 30℃ and 180r / min for 36h with aerobic shaking. (2) Inoculate Weissella esculenta zqw90 into MRS liquid medium and incubate at 30°C for 48 h. (3) Enterobacter zqw26 was inoculated into MRS liquid medium and cultured at 30°C and 120 r / min for 48 h with facultative anaerobic shaking. (4) Neurospora crassa N7 was inoculated into straw inorganic salt medium and cultured at 25℃ and 150r / min aerobic shaking for 96h; (5) Mix the culture solutions of 5 strains of bacteria according to the mass ratio of live bacteria 2:2:2:2:3; add 2% trehalose and 2% glycerol as composite protectants as total mass of bacterial solution, stir for 30 min until uniform, and obtain the low-temperature composting compound bacterial agent.

[0029] Example 2 A low-temperature composting compound microbial agent with a total effective viable count of 7.5 × 10⁻⁶ bacteria. 9 CFU / g, including Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella tamariscina zqw90, Weissella enterica zqw26 and Neurospora crassa N7.

[0030] Its preparation method is as follows: (1) Stenotrophomonas maltophilia JGDQ29-2 and Bacillus JX-7 were inoculated into LB solid medium and cultured at 30℃ and 180r / min for 36h with aerobic shaking. (2) Inoculate Weissella esculenta zqw90 into MRS liquid medium and incubate at 30°C for 48 h. (3) Enterobacter zqw26 was inoculated into MRS liquid medium and cultured at 30°C and 120 r / min for 48 h with facultative anaerobic shaking. (4) Neurospora crassa N7 was inoculated into straw inorganic salt medium and cultured at 25℃ and 150r / min aerobic shaking for 96h; (5) Mix the culture solutions of 5 strains of bacteria according to the mass ratio of live bacteria 1:1:1:1:2.5; add 2% trehalose and 2% glycerol as composite protectants as total mass of bacterial solution, stir for 30 min until uniform, and obtain the low-temperature composting compound bacterial agent.

[0031] Example 3 A low-temperature composting compound microbial agent with a total effective viable count of 8.5 × 10⁻⁶ bacteria. 9 CFU / g, including Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella tamariscina zqw90, Weissella enterica zqw26 and Neurospora crassa N7.

[0032] Its preparation method is as follows: (1) Stenotrophomonas maltophilia JGDQ29-2 and Bacillus JX-7 were inoculated into LB solid medium and cultured at 30℃ and 180r / min for 36h with aerobic shaking. (2) Inoculate Weissella esculenta zqw90 into MRS liquid medium and incubate at 30°C for 48 h. (3) Enterobacter zqw26 was inoculated into MRS liquid medium and cultured at 30°C and 120 r / min for 48 h with facultative anaerobic shaking. (4) Neurospora crassa N7 was inoculated into straw inorganic salt medium and cultured at 25℃ and 150r / min aerobic shaking for 96h; (5) Mix the culture solutions of 5 strains of bacteria according to the mass ratio of live bacteria 1.5:1.5:1.5:1.5:2; add 2% trehalose and 2% glycerol as composite protectants as total mass of bacterial solution, stir for 30 min until uniform, and obtain the low temperature composting compound bacterial agent.

[0033] Comparative Example 1 Blank control (no bacterial agent used).

[0034] Comparative Example 2 The compound microbial agent in this comparative example is composed of Neurospora crassa (… Neurospora crassa N7 and Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia The composition is JGDQ29-2, and the rest of the process is the same as in Example 1.

[0035] Comparative Example 3 The compound microbial agent in this comparative example is composed of Neurospora crassa (… Neurospora crassa N7, Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia JGDQ29-2 and Penicillium oxalate ( Penicillium oxalicum The ATCC10476 is composed of the same components, and the rest of the process is the same as in Example 1.

[0036] Comparative Example 4 The compound microbial agent in this comparative example is composed of Neurospora crassa (… Neurospora crassa N7, Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia JGDQ29-2, Trichoderma reesei ( Trichoderma reesei ATCC56765, Bacillus subtilis ( Bacillus subtilis The ATCC6633 is composed of the same components, and the rest of the process is the same as in Example 1.

[0037] Test case 1. Antagonistic experiment between microorganisms in compound bacterial agents Testing of Neurospora crassa using the plate confrontation culture method ( Neurospora crassa N7 and four other bacterial strains, namely Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia JGDQ29-2, Bacillus ( Bacillus sp.) JX-7, Weissella esculenta (sp.) JX-7, Weissella esculenta ( Weissella cibaria zqw90, Enterobacter sieboldii ( Weissella cibaria Does zqw26 have an antagonistic effect?

[0038] First, activate Neurospora crassa using a PDA plate. Neurospora crassa N7 was cultured at 25℃ for 7 days. After the fungal culture was complete, four bacterial single clones were activated 1-2 days in advance. JGDQ29-2 and JX-7 were cultured on LB solid medium, and zqw90 and zqw26 were cultured on MRS solid medium.

[0039] Take more than 10 µL of activated bacterial suspension and spot it on both sides of a WA plate. Inoculate the center of the plate with Neurospora crassa (…). Neurospora crassa N7 fungal hyphae were collected, and plates without bacterial inoculation were used as a control. The plates were cultured at room temperature, and the diameter of the fungal colonies was observed to be affected by bacterial growth compared with the control.

[0040] If the diameter of fungal colonies remains unchanged regardless of the presence or absence of bacteria, it indicates that *Neurospora crassa* (… Neurospora thick There is no antagonistic effect between N7 and the corresponding bacteria; otherwise, it indicates that there is an antagonistic effect between them.

[0041] WA medium (Waksman's agar): peptone 15 g / L, glucose 10 g / L, beef extract 3 g / L, NaCl 5 g / L, agar 15 g / L.

[0042] like Figure 1 As shown, the results of confrontation culture on WA plates are presented, compared with the control group inoculated with a single hyphae of the fungus to be tested in the middle of the plate ( Figure 1 Left), the fungus Neurospora roughiflora ( Neurospora crassaN7 hyphae spread to the bacterial colony, interacting with the bacteria Stenotrophomonas maltophilia (… Stenotrophomonas maltophilia JGDQ29-2, Bacillus ( Bacillus sp.) JX-7, Weissella esculenta (sp.) JX-7, Weissella esculenta ( Weissella cibaria No antagonistic reaction occurred with zqw90. Figure 1 (Right), which can be used in the development of compound bacterial agents.

[0043] 2. Field experiment on the application of low-temperature decomposition-promoting compound microbial agent when straw is returned to the field To fully leverage the decomposition potential of low-temperature compound microbial agents for in-situ straw decomposition, the agents are applied in the field during the spring fallow period. For paddy fields, the decomposition evaluation of rice straw is conducted by applying the agents in mid-April before the paddy fields are stirred, while for dry fields, the decomposition evaluation of corn straw is conducted in early May before the soil is rotary tilled and ridged.

[0044] To verify the effects of low-temperature decomposition-promoting compound microbial agents on in-situ decomposition and soil organic matter enhancement, PVC pipe experiments (paddy fields), net bag experiments (dry fields), and plot experiments were conducted. The PVC pipe and net bag experiments facilitated quantitative monitoring of the straw decomposition process throughout the entire process, while the plot experiment allowed for a better assessment of the effects of the microbial agent on soil improvement and crop yield. Figure 2 The specific process is as follows: (1) PVC pipe method Perforated PVC pipes with a diameter of 12-16 cm, a length of 23-25 ​​cm, and a thickness of 3-5 mm were selected. Each PVC pipe contained a measured amount of rice straw, soil, and microbial agent mixture. 34 g of rice straw was weighed and mixed thoroughly with 170 mL of microbial agent, then mixed with a certain amount of soil sample until each experimental group contained 3 × 10⁻⁶ bacteria. 9 CFU / tube, fungi 3×10 7 Each spore / tube is used to position the prepared PVC pipe in the field.

[0045] (2) Nylon mesh bag method Mesh bags measuring 40×60 cm were used, each containing a measured amount of corn stalks, soil, and inoculant mixture. Each experimental group contained 3×10⁶ bacteria. 9 CFU / bag, fungi 3×10 7 The inoculant is applied according to the standard of one spore / bag. The amount of crop straw used is 40 g of corn straw. It is mixed with a certain amount of soil sample and then the net bags are buried in the soil at a depth of 30-50 cm and an interval of about 60 cm, and positioned in the cornfield.

[0046] (3) Community Experiment The experimental fields in each demonstration area ranged in size from approximately 10 to 50 mu (about 0.67-0.33 hectares). Inoculant was sprayed before spring planting, with the application time determined based on the optimal planting time for each demonstration area. The application rate was 3.75 × 10⁻⁶ bacteria. 12 CFU / mu, fungi 3.75×10 11 1 spore per acre.

[0047] Sampling and Implementation Plan: For the PVC pipe and mesh bag experiments, at least three replicates were set up for each experimental group. Samples were collected and analyzed in July, 60 days after the application of the microbial agent. Simultaneously, the straw decomposition rate in the soil was measured, and eight physiological and biochemical indicators of the soil samples were analyzed, including soil pH, organic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium.

[0048] The small-scale experiment was conducted in September and October, with timely harvesting and yield measurement based on local crop growth conditions.

[0049] As shown in Table 1, in Example 1 of applying the microbial agent of the present invention to paddy fields, compared with Comparative Example 1 without applying the microbial agent, the decomposition rate increased by 27.70%, organic matter increased by 25.35%, available nitrogen increased by 72.35%, available potassium increased by 19.04%, and yield increased by 24.26%.

[0050] Table 1. Efficacy of applying microbial agents when returning all rice straw to the field in paddy fields in Northeast China

[0051] As shown in Table 2, in Example 1 of applying the microbial agent of the present invention to a cornfield, compared with Comparative Example 1 without the application of the microbial agent, the decomposition rate and eight soil indicators were comprehensively improved. Specifically, the decomposition rate increased by 12.02%, organic matter increased by 51.67%, total nitrogen increased by 58.06%, available nitrogen increased by 24.43%, total phosphorus increased by 82.76%, available phosphorus increased by 2.87 times, total potassium increased by 74.58%, available potassium increased by 79.71%, and the yield increased by 12.02%.

[0052] Table 2. Efficacy of applying microbial agents when returning all corn straw to the field in dryland areas of Northeast China.

[0053] 3. Effects of low-temperature decomposition-promoting compound microbial agents on soybean fields A low-temperature decomposition-promoting compound microbial agent was applied to a rice-soybean crop rotation dryland experiment. The previous year's crop was corn, and after harvest, all corn stalks were returned to the field. The following year, soybeans were planted. To accurately determine the in-situ decomposition performance of the corn stalks, this invention used a mesh bag method to measure the in-situ decomposition of the corn stalks. The specific experimental description is the same as above.

[0054] As shown in Table 3, in Example 1 of applying the microbial agent of the present invention to dryland rice-bean rotation, compared with Comparative Example 1 without the application of the microbial agent, the decomposition rate increased by 17.25%, organic matter increased by 1.85%, available phosphorus increased by 83.64%, and yield increased by 59.82%.

[0055] Table 3. Effectiveness of Microbial Agent Application in Full-Scale Corn Stalk Return to Field (Rice-Soybean Rotation) in Dryland Farms of Northeast China

[0056] 4. The effect of low-temperature decomposition-promoting compound microbial agents on saline-alkali paddy fields and dry fields. The low-temperature decomposition-promoting compound microbial agent was applied to rice paddies and cornfields with a pH higher than 9 in experiments. The specific experimental design and treatment group descriptions are the same as above, and the specific experimental operations are the same as above.

[0057] As shown in Tables 4 and 5, in Example 1 of applying the microbial agent of the present invention to saline-alkali paddy fields, compared with Comparative Example 1 without the application of the microbial agent, the pH decreased from 9.24 to 8.97, the decomposition rate increased by 44.88%, the organic matter increased by 19.37%, the total nitrogen increased by 37.84%, the available nitrogen increased by 1.56%, the available potassium increased by 17.59%, and the yield increased by 8.22%.

[0058] In Example 1, which describes the application of the microbial agent of the present invention in a saline-alkali cornfield, compared with Comparative Example 1 (without the application of the microbial agent), the pH decreased slightly from 9.42 to 9.29, organic matter increased by 14.06%, available nitrogen increased by 65.20%, available phosphorus increased by 16.55%, total potassium increased by 26.94%, available potassium increased by 46.48%, and yield increased by 11.11%.

[0059] Table 4. Efficacy of applying microbial agents when returning all rice straw to paddy fields in saline-alkali land in Northeast China.

[0060] Table 5. Efficacy of applying microbial agents when returning all corn straw to dryland in saline-alkali land in Northeast China.

[0061] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, 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 technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A low-temperature composting compound microbial agent, characterized in that, Including Stenotrophomonas maltophilia with a viable count-to-mass ratio of 1~2:1~2:1~2:1.5~2:2.5~3 ( Stenotrophomonas maltophilia JGDQ29-2, Bacillus ( Bacillus sp.) JX-7, Weissella esculenta (sp.) JX-7, Weissella esculenta ( Weissella cibaria zqw90, Enterobacter sieboldii ( Weissella cibaria zqw26 and Neurospora crassa ( Neurospora crassa )N7.

2. The low-temperature composting compound microbial agent according to claim 1, characterized in that, The viable count mass ratio of Stenotrophomonas maltophilia JGDQ29-2, Bacillus JX-7, Weissella maltophilia zqw90, Weissella enterica zqw26, and Neurospora crassa N7 was 1.5~2:1.5~2:1.5~2:1.5~2:

3.

3. The low-temperature composting compound microbial agent according to claim 1 or 2, characterized in that, Stenotrophomonas maltophilia JGDQ29-2 was deposited at the China General Microbiological Culture Collection Center on July 24, 2023, with accession number CGMCC No. 27979; Bacillus JX-7 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on July 24, 2023, with accession number CGMCC No. 27978; Weissella esculenta zqw90 was deposited at the China General Microbiological Culture Collection Center on June 21, 2022, with accession number CGMCC No. 25149; Enterobacter vesiculosus zqw26 was deposited at the China General Microbiological Culture Collection Center on June 21, 2022, with accession number CGMCC No. 25137; Neurospora crassa N7 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on July 24, 2023, with accession number CGMCC No. 40738.

4. The low-temperature composting compound microbial agent according to any one of claims 1 to 3, characterized in that, The total effective viable count of the low-temperature composting compound microbial agent is ≥1.0×10⁻⁶. 9 CFU / g.

5. A method for preparing the low-temperature composting compound microbial agent according to any one of claims 1 to 4, characterized in that, Each strain was inoculated into a culture medium and cultured separately. Seed liquid was harvested, and then the seed liquids of each strain were mixed in proportion to prepare the low-temperature composting compound microbial agent.

6. The preparation method according to claim 5, characterized in that, Stenotrophomonas maltophilia JGDQ29-2 and Bacillus JX-7 were inoculated into LB solid medium and cultured aerobically with shaking at 30-35°C for 34-40 h. Weissella esculenta zqw90 was inoculated into MRS liquid medium and incubated statically at 30-35°C for 34-40 h; Enterobacter vesiculosus zqw26 was inoculated into MRS liquid medium and cultured in a facultative anaerobic shaking culture at 30-35℃ for 46-50 h; Neurospora crassa N7 was inoculated into straw-inorganic salt medium and cultured aerobically with shaking at 24-28℃ for 92-100 h.

7. A method for efficient in-situ straw return to the field, characterized in that, After the straw is crushed, it is mixed with the low-temperature decomposition-promoting compound microbial agent described in any one of claims 1 to 4 and returned to the field. Alternatively, the straw can be crushed and evenly spread on the field surface. After rotational tillage to increase oxygen, the field can be flooded, and then the low-temperature decomposition-promoting compound microbial agent can be applied, followed by stirring and returning the slurry to the field.

8. The use of the low-temperature composting compound microbial agent according to any one of claims 1 to 4 in the preparation of a formulation for improving saline-alkali land.

9. The use of the low-temperature composting compound microbial agent according to any one of claims 1 to 4 or the preparation according to claim 8 in increasing crop yield.

10. The use according to claim 9, characterized in that, The crops are corn, soybeans, or rice.

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