Preparation method of cassava residue bagasse compost modified by composite functional bacteria and rice husk charcoal and application thereof

Abstract

The present application relates to the technical field of agricultural waste resource utilization and organic fertilizer, and is a preparation method and application of cassava residue and bagasse compost modified by adding composite functional bacteria and combined with rice husk carbon, which can simultaneously realize efficient degradation of lignocellulose, control of nitrogen loss, and improvement of compost quality, and promote the resource utilization of cassava residue and bagasse and the sustainable development of agriculture.

Description

Technical Field

[0001] This invention relates to the field of agricultural waste resource utilization and organic fertilizer technology, specifically a method for preparing cassava residue and bagasse compost using cassava residue and bagasse as the main raw materials, with the addition of compound functional bacteria and rice husk charcoal for improvement, and its application. Background Technology

[0002] Cassava, a drought-resistant and barren-fertility high-starch crop, is widely cultivated in Guangxi and other regions of my country. The annual output of cassava residue generated during starch production reaches 1.5 million tons. Sugarcane bagasse, produced during sugarcane planting and processing, also generates a huge amount of waste. Both are rich in lignocellulose (cellulose, hemicellulose, and lignin) and are widely sourced agricultural solid wastes. However, the lignocellulose structure in cassava and sugarcane bagasse is stubborn and degrades slowly. Without effective treatment, they not only occupy a large amount of storage space but also cause environmental pollution and serious resource waste.

[0003] Aerobic composting is an effective way to utilize agricultural waste as a resource, converting it into organic fertilizer, reducing environmental pollution, and removing pathogenic microorganisms. However, traditional aerobic composting has significant limitations for materials with high lignocellulose content: lignocellulose is difficult to degrade, resulting in a long composting cycle and low decomposition efficiency; gaseous nitrogen such as ammonia (NH3) and nitrous oxide (N2O) are easily emitted during composting, causing a large loss of nitrogen and reducing the nutrient value of the compost; at the same time, the degree of humification in the compost is insufficient, affecting product quality.

[0004] While some studies have attempted to improve compost by adding single-function microbial strains or biochar, existing technologies have several shortcomings: single microbial strains can only target specific components and cannot simultaneously address the issues of lignocellulose degradation and nitrogen loss; when biochar is added alone, its promoting effect on microbial activity is not significant enough to fully realize its synergistic effect. Currently, there is limited research on the combined application of lignin-degrading bacteria, cellulose-degrading bacteria, nitrogen-fixing bacteria, and rice husk char in cassava bagasse co-composting. The technical solutions for synergistically enhancing carbon and nitrogen conversion and promoting humification are not yet clear, failing to meet the demand for efficient resource utilization of agricultural waste. Summary of the Invention

[0005] To address the problems of slow lignocellulose degradation, large nitrogen loss, long composting cycle, and low maturity in existing cassava residue-bagasse compost, this invention provides a compost preparation method that combines composite functional bacteria with rice husk charcoal. Through the synergistic effect of the bacteria and rice husk charcoal, efficient degradation of lignocellulose is achieved simultaneously, carbon and nitrogen conversion efficiency is enhanced during composting, and compost maturity and nutrient content are improved, thus realizing the efficient resource utilization of agricultural waste.

[0006] A method for preparing cassava residue and bagasse compost improved by combining compound functional bacteria and rice husk charcoal: using cassava residue and bagasse as the main raw materials, compound functional bacteria and rice husk charcoal are added, and the compost is prepared by aerobic fermentation; the raw materials are prepared in the following weight ratio: cassava residue: bagasse: compound functional bacteria: rice husk charcoal = 30-50: 20-40: 1-5: 3-5.

[0007] The composite functional bacteria are prepared by mixing highly efficient lignocellulose-degrading bacteria and nitrogen-fixing bacteria; the lignocellulose-degrading bacteria include *Phanerochaete chrysosporium* and *Trichoderma* strains. Trichoderma sp. LH-413, among which, Trichoderma sp. LH-413 is classified as belonging to the genus Trichoderma ( Trichoderma sp. The nitrogen-fixing bacteria are deposited at the China Center for Type Culture Collection (CCTCC), accession number CCTCC NO: M2023749; Azotobacter sp., Accession number: CICC 20024; the *Phanerochaete chrysosporium*, accession number: ATCC24725, was purchased from the China Industrial Microbial Culture Collection Center.

[0008] The method of the present invention includes the following steps: a. Raw material pretreatment: Cassava residue and bagasse are crushed to a particle size of ≤5 mm, mixed evenly, and the initial moisture content is adjusted to 55%~65% and the carbon-nitrogen ratio (C / N) to 22~28 by adding water to obtain loose and breathable compost base material; b. Strain preparation: The compound inoculum of lignocellulose-degrading bacteria and nitrogen-fixing bacteria were separately cultured until the activity of all three was ≥1×10⁻⁶. 9 After CFU / mL, the volume ratio of *Phanerochaete chrysosporium* was: Trichoderma sp. LH-413: Nitrogen-fixing bacteria Azotobacter sp.= A mixture of 3:3:2 yields a compound functional bacteria; c. Combined fermentation: Mix functional bacteria and rice husk charcoal evenly into the compost base material, stir thoroughly, and then carry out aerobic composting. During the composting process, control the aeration rate to 0.05-0.1 m³ / (m³·h). Among them, rice husk charcoal utilizes its porous structure and surface functional groups to adsorb and fix ammonia (NH3) and ammonium nitrogen generated in the compost pile, while providing an attachment carrier and suitable microenvironment for the functional bacteria, synergistically reducing nitrogen volatilization loss and promoting efficient conversion of organic matter. d. Composting management: Turn the compost pile every 3-7 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 45-48 days. During this period, maintain the high temperature of the compost pile above 55°C for 10-15 days to achieve the inactivation of pathogens and the full decomposition of organic matter.

[0009] As described above, the application of a composite functional bacteria and rice husk charcoal-modified cassava bagasse compost in crop cultivation substrates or soil conditioners.

[0010] The functional strains in the composite microbial strains rapidly proliferate in the composting environment and form a dominant microbial community, synergistically degrading the lignocellulose, residual fiber, and organic matter enriched in cassava residue and sugarcane bagasse: lignin-degrading bacteria (Phanerochaete chrysosporium and Trichoderma strains) Trichoderma sp. LH-413 secretes laccase, peroxidase, and other lignin-degrading enzymes, preferentially disrupting the lignin barrier and increasing substrate accessibility; cellulose-degrading bacteria secrete cellulase, hemicellulase, etc., further hydrolyzing cellulose and hemicellulose, releasing usable carbon sources and accelerating the humification process; nitrogen-fixing bacteria ( Azotobacter sp In the pores of rice husk charcoal and the moist microenvironment of the compost, nitrogen in the air is fixed and converted into microbial assimilated nitrogen / organic nitrogen. Combined with the adsorption and fixation of NH3 / ammonium nitrogen by rice husk charcoal, the effective nitrogen loss caused by NH3 volatilization is reduced, thereby improving the nitrogen nutrition level of the compost product.

[0011] Rice husk char has a large specific surface area and well-developed pore structure, which can improve the aeration and water retention conditions of the compost pile and provide an attachment carrier and microenvironment for complex functional microorganisms. At the same time, rice husk char can adsorb and fix ammonia (NH3) and ammonium nitrogen generated during composting through pore adsorption and surface functional group action, reducing NH3 volatilization and nitrogen loss. In addition, its surface active sites can promote the polymerization and transformation of humic precursor substances, thereby further improving the degree of humification and quality of compost products.

[0012] The beneficial effects of this invention are: 1. This invention employs a composite microbial agent composed of highly efficient lignin-degrading bacteria, cellulose-degrading bacteria, and two nitrogen-fixing bacteria, which is added in combination with rice husk charcoal. The composite microbial agent destroys the lignin-cellulose structure and accelerates the degradation of cellulose, hemicellulose, and lignin by secreting lignin-degrading enzymes and cellulases. At the same time, the nitrogen-fixing bacteria fix atmospheric nitrogen and promote the conversion of nitrogen into microbial assimilated nitrogen / organic nitrogen. The rice husk charcoal adsorbs and fixes ammonia gas generated during composting and provides a colonization carrier, thereby achieving a synergistic effect of "promoting degradation - nitrogen fixation and supplementation - ammonia absorption and nitrogen retention", overcoming the functional limitations of single microbial species or single biochar. 2. By efficiently degrading lignocellulose and promoting humification with compound microbial agents, and by adsorbing and fixing ammonia with rice husk charcoal and working with nitrogen-fixing bacteria to improve nitrogen retention, the composting fermentation cycle of this invention is shortened to 45-48 days. The total degradation rate of lignocellulose can reach up to 47%, the total nitrogen content reaches 2.9%, the humic acid content reaches 12%, the seed germination index reaches 90%, the product is odorless, and the heavy metal content meets the NY / T 1978-2022 standard. The compost quality is significantly better than traditional compost. This invention achieves efficient resource utilization of agricultural waste such as cassava residue and bagasse, reduces environmental pollution, and the prepared compost can improve soil fertility and promote crop growth, meeting the needs of sustainable agricultural development. Attached Figure Description

[0014] Figure 1 A schematic diagram showing the changes in total degradation rate of lignocellulose and total nitrogen content in cassava residue compost. Figure 2 A schematic diagram showing the humic acid content and seed germination index of cassava residue compost. Detailed Implementation

[0015] To better understand the content of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. The invention will be further explained below with reference to the embodiments, but this should not be construed as limiting the invention.

[0016] In the following embodiments, the bacterial strains were first streaked on the corresponding agar plates and then expanded in liquid culture medium. Microscopic examination of each bacterial culture revealed no contamination and an activity ≥1×10⁻⁶. 9 Once the concentration of CFU / mL is reached, it can be used for the preparation of mixed bacterial strains.

[0017] Comparative Examples This embodiment does not use compound functional bacteria and rice husk charcoal, but adopts a traditional composting method, with the following steps: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Fermentation: The compost base material is directly subjected to aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). The compost is turned over once every 5 days for the first 20 days, and once every 7 days thereafter, with a total fermentation cycle of 48 days.

[0018] The compost product was measured to be yellowish-brown with a slight odor, pH 7.8, electrical conductivity 3.2 mS / cm, seed germination index 65%, total lignocellulose degradation rate 22%, total nitrogen content 1.8%, and humic acid content 6%. The overall effect was far inferior to that of the embodiments of the present invention.

[0019] Example 1 (Lignocellulose-degrading bacteria only) This embodiment only adds lignocellulose-degrading bacteria (i.e., *Phanerochaete chrysosporium* from the compound microbial agent) + Trichoderma sp. LH-413) verifies the limitations of single-strain degrading bacteria, highlighting the synergistic degradation advantages of compound bacterial agents. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Fermentation treatment: Add 3 parts of lignocellulose degrading bacteria (no nitrogen-fixing bacteria, no rice husk char) to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Composting management: Turn the compost every 5 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55 ℃) is maintained for 12 days.

[0020] The compost product was measured to be dark brown with no obvious odor, pH 7.2, electrical conductivity 2.6 mS / cm, and seed germination index 82%. The total degradation rate of lignocellulose was 35% (it could only destroy the lignin barrier, lacking synergistic effects of cellulose-degrading bacteria and nitrogen-fixing bacteria, resulting in limited degradation efficiency); the total nitrogen content was 1.7% (no nitrogen fixation or supplementation, no nitrogen retention measures, and severe nitrogen loss); and the humic acid content was 9.0% (moderate degree of humification), highlighting the functional limitations of a single degradation strain.

[0021] Example 2 (only nitrogen-fixing bacteria group added) This embodiment only adds nitrogen-fixing bacteria ( Azotobacter sp. To verify the limitations of a single nitrogen-fixing bacterial species and highlight the synergistic degradation advantages of the compound bacterial agent, the steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Fermentation treatment: Add 3 parts of nitrogen-fixing bacteria (without lignocellulose-degrading bacteria and without rice husk char) to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Compost management: Turn the compost pile every 5 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55℃) is maintained for 11 days.

[0022] The compost product was measured to be yellowish-brown, odorless, with a pH of 7.3, an electrical conductivity of 2.5 mS / cm, and a seed germination index of 78%. The total degradation rate of lignocellulose was 28% (it could only slightly promote natural degradation through metabolites, lacked efficient degradation enzymes, and had poor degradation effect); the total nitrogen content was 2.3% (it had outstanding nitrogen fixation function, but lacked degrading bacteria to synergistically improve compost quality); and the humic acid content was 7.5% (low degree of humification), further confirming that a single strain of bacteria cannot simultaneously address degradation and nutrient retention.

[0023] Example 3 (only the compound functional bacterial strain group was added) This embodiment only adds a compound functional strain to verify its dual core advantages of "degradation + nitrogen fixation" and eliminates the interference of rice husk charcoal. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Fermentation treatment: Add 3 parts of compound functional bacteria (without rice husk charcoal) to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h); c. Compost management: Turn the compost pile every 4 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55℃) is maintained for 11 days.

[0024] Tests showed that the compost product was dark brown, odorless, with a pH of 7.1, an electrical conductivity of 2.4 mS / cm, a seed germination index of 84%, and a total lignocellulose degradation rate of 45% (lignin-degrading bacteria and cellulose-degrading bacteria synergistically secreted degradation enzymes, and nitrogen-fixing bacteria metabolites helped improve degradation efficiency, resulting in a degradation effect far exceeding that of the single-strain group); the total nitrogen content was 2.0% (nitrogen-fixing bacteria effectively supplemented nitrogen, and although there was no rice husk charcoal to retain nitrogen, the nitrogen content was still higher than that of the single-strain group); and the humic acid content was 10.5% (the microbial agents synergistically promoted humification, resulting in a quality superior to single-strain compost), clearly highlighting the synergistic advantages of the compound microbial agents.

[0025] Example 4 (with only rice husk charcoal added) In this embodiment, only rice husk charcoal was added to verify its single adsorption and nitrogen retention efficiency, excluding the influence of microbial strains on degradation. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Fermentation treatment: Add 3 parts rice husk charcoal (without compound functional bacteria) to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h); c. Compost management: Turn the compost pile every 3 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55℃) is maintained for 10 days.

[0026] The compost product was measured to be dark brown and odorless, with a pH of 7.0, an electrical conductivity of 2.3 mS / cm, a seed germination index of 80%, a total lignocellulose degradation rate of 30% (significantly better than the 22% in the unadded group, mainly due to the natural degradation of the compost and the aeration effect of rice husk charcoal), a total nitrogen content of 2.4% (rice husk charcoal has a significant adsorption and fixation effect on ammonia (NH3) generated during composting, reducing nitrogen loss caused by NH3 volatilization, thus demonstrating a significant nitrogen retention effect), and a humic acid content of 8.5% (due to the lack of added compound microbial agents, the humification promotion effect is limited). This indicates that rice husk charcoal alone can achieve ammonia absorption and nitrogen retention, but its effect on the deep degradation of lignocellulose and the enhancement of humification is relatively insufficient.

[0027] Example 5 (Low bacterial strain + low rice husk charcoal group) This embodiment uses a low-dose combination of microbial inoculum and rice husk charcoal to verify the basic synergistic effect. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Combined fermentation: Add 1 part of compound functional bacteria and 3 parts of rice husk charcoal to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Compost management: Turn the compost pile every 5 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55℃) is maintained for 12 days.

[0028] The compost product was measured to be dark brown and odorless, with a pH of 7.1, an electrical conductivity of 2.5 mS / cm, a seed germination index of 85%, a total lignocellulose degradation rate of 38% (the compound microbial agent played a basic degradation role), a total nitrogen content of 2.5% (rice husk char adsorbed and fixed ammonia (NH3) and provided a microbial carrier, which, together with the nitrogen-fixing bacteria, improved nitrogen retention), and a humic acid content of 9.5% (the microbial agent promoted humification). All indicators were superior to the single-addition group, reflecting the synergistic effect between the compound microbial agent's "promoting degradation / nitrogen fixation" and the rice husk char's "ammonia absorption and nitrogen retention / carrier".

[0029] Example 6 (medium-sized bacterial strain + medium-sized rice husk charcoal group, preferred dosage) This embodiment uses a moderate dosage compound ratio to achieve a three-dimensional balance of degradation, nitrogen retention, and humification, resulting in the optimal overall effect. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Combined fermentation: Add 3 parts of compound functional bacteria and 4 parts of rice husk charcoal to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Composting management: Turn the compost every 5 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55 ℃) is maintained for 12 days.

[0030] The compost product was measured to be dark brown and odorless, with a pH of 7.3, an electrical conductivity of 2.5 mS / cm, a seed germination index of 90%, a total lignocellulose degradation rate of 45% (due to the efficient secretion of degradation enzymes by the compound microbial agent, resulting in synergistic degradation of lignocellulose), a total nitrogen content of 2.9% (due to the combined effect of NH3 adsorption and fixation by rice husk charcoal, nitrogen supplementation by nitrogen-fixing bacteria, and microbial assimilation and fixation, achieving high nitrogen retention), and a humic acid content of 12.0% (due to a high degree of humification). It achieves a balance between degradation efficiency, ammonia absorption and nitrogen retention, and humification level, with comprehensive performance far exceeding that of single-addition groups and other compound groups.

[0031] Example 7 (Low bacterial strain + high rice husk charcoal group) This embodiment focuses on using a high amount of rice husk charcoal to enhance nitrogen retention and weaken the degradation effect of microorganisms. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Combined fermentation: Add 2 parts of compound functional bacteria and 5 parts of rice husk charcoal to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Compost management: Turn the compost pile every 5 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55℃) is maintained for 13 days.

[0032] The compost product was measured to be dark brown and odorless, with a pH of 7.2, an electrical conductivity of 2.5 mS / cm, a seed germination index of 86%, a total degradation rate of lignocellulose of 42% (the low dosage of microbial agent limited the supply of degradation enzymes, resulting in a lower degradation rate than the optimal dosage group), a total nitrogen content of 2.8% (high rice husk charcoal dosage had a stronger ability to adsorb and fix NH3, and the ammonia absorption and nitrogen retention effect was the most prominent), and a humic acid content of 10.2% (affected by insufficient microbial agent, the degree of humification was lower than the optimal dosage group). This indicates that rice husk charcoal mainly contributes to ammonia absorption and nitrogen retention, while the deep degradation and humification of lignocellulose still depend on the compound microbial agent.

[0033] Example 8 (High bacterial strain + low rice husk charcoal group) This embodiment emphasizes a high dosage of microbial strains to enhance degradation and humification effects, while weakening the nitrogen-retaining effect of rice husk charcoal. The steps are as follows: a. Raw material pretreatment: Take 35 parts cassava residue and 25 parts bagasse, crush them to a particle size ≤ 5 mm, mix them evenly, adjust the initial moisture content to 60% and C / N to 25 to obtain compost base material; b. Combined fermentation: Add 5 parts of compound functional bacteria and 3 parts of rice husk charcoal to the compost base material, mix thoroughly and then carry out aerobic composting, maintaining an aeration rate of 0.075 m³ / (m³·h). c. Compost management: Turn the compost pile every 6 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 48 days, during which a high temperature period (≥55 ℃) is maintained for 14 days.

[0034] The compost product was measured to be dark brown and odorless, with a pH of 7.1, an electrical conductivity of 2.3 mS / cm, a seed germination index of 89%, a total lignocellulose degradation rate of 47% (high microbial inoculum usage promotes enzyme secretion, resulting in the most complete degradation of lignocellulose), a total nitrogen content of 2.3% (low rice husk char content limits the adsorption and fixation capacity for ammonia (NH3) generated during composting; under strong degradation / mineralization conditions, ammonification is enhanced, making NH3 more volatile, thus limiting nitrogen retention), and a humic acid content of 11.5% (high degree of humification). This indicates that the compound microbial agent can significantly promote lignocellulose degradation and humification, but insufficient rice husk char content will become a limiting factor in ammonia absorption and nitrogen retention.

[0035] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing cassava bagasse compost improved by a combination of compound functional bacteria and rice husk charcoal, characterized in that, The main raw materials are cassava residue and sugarcane bagasse, with the addition of compound functional bacteria and rice husk charcoal. The raw materials are prepared in the following weight ratio: cassava residue: sugarcane bagasse: compound functional bacteria: rice husk charcoal = 30-50: 20-40: 1-5: 3-5.

2. The preparation method according to claim 1, characterized in that, The composite functional bacterial strain is prepared by mixing highly efficient lignocellulose-degrading bacteria and a nitrogen-fixing bacterium; the lignocellulose-degrading bacteria include *Phanerochaete chrysosporium* and *Trichoderma* strains. Trichoderma sp. LH-413, among which, Trichoderma sp. LH-413 is classified as belonging to the genus Trichoderma ( Trichoderma sp. The nitrogen-fixing bacteria are deposited at the China Center for Type Culture Collection (CCTCC), accession number CCTCC NO: M2023749; Azotobacter sp. (Accession number: CICC 20024).

3. The preparation method according to claim 1, characterized in that, Includes the following steps: a. Raw material pretreatment: Cassava residue and bagasse are crushed to a particle size of ≤5 mm, mixed evenly, and the initial moisture content is adjusted to 55%-65% and the carbon-nitrogen ratio (C / N) is adjusted to 22-28 by adding water to obtain loose and breathable compost base material; b. Strain preparation: The compound inoculum of lignocellulose-degrading bacteria and nitrogen-fixing bacteria were separately cultured and expanded until the activity of each strain was ≥1×10⁻⁶. 9 After CFU / mL, the volume ratio of *Phanerochaete chrysosporium* was: Trichoderma sp. LH-413: Nitrogen-fixing bacteria Azotobacter sp.= A mixture of 3:3:2 yields a compound functional bacteria; c. Combined fermentation: Introduce functional bacteria and rice husk charcoal evenly into the compost substrate, mix thoroughly, and then perform aerobic composting. During composting, control the aeration rate to 0.05-0.1 m³ / (m³·h). d. Composting management: Turn the compost pile every 3-7 days for the first 20 days, and every 7 days thereafter. The total fermentation cycle is 45-48 days. During this period, maintain the high temperature of the compost pile above 55°C for 10-15 days.

4. The use of compost prepared by any one of claims 1-3 in crop cultivation substrates or soil conditioners.

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