Application of fungicide for promoting carbon immobilization in red soil rice field

Abstract

The invention belongs to the technical field of microbial agents for soil improvement, and particularly relates to application of a microbial agent for promoting carbon immobilization of a red soil rice field. The microbial inoculum is rhodococcus erythropolis or a synthetic microbial inoculum of rhodococcus erythropolis and pseudomonas aeruginosa, and after the rice seedlings are transplanted to red soil for 3 days, 25mL of suspension liquid of the related microbial inoculum is inoculated to the rhizosphere of each rice seedling. According to the application, the rhizosphere microenvironment is improved, input of plant photosynthetic carbon into soil is activated, meanwhile, the carbon utilization efficiency and conversion capacity of soil in-situ microbial communities are remarkably improved, accumulation of microbial source carbon is promoted, the molecular composition structure of soluble organic matter is remodeled, and finally formation and accumulation of a soil carbon library are promoted and stabilized.

Description

Technical Field

[0001] This invention belongs to the technical field of microbial agents for soil improvement, and specifically relates to the application of a microbial agent for promoting carbon sequestration in red soil paddy fields. Background Technology

[0002] Soil organic carbon is the core of soil fertility and a key to achieving sustainable farmland production. However, red soil, as a major agricultural soil type, is generally highly acidic (pH < 5.5) due to intense weathering and leaching, which inhibits microbial carbon use efficiency. This results in the ineffective conversion of input carbon sources, leading to loss through respiration, and consequently, a generally low organic carbon content. Furthermore, the hot and humid climate of southern regions and the frequent tillage and irrigation of paddy fields further exacerbate the rapid mineralization of soil organic carbon, making red soil paddy fields a potential carbon source rather than a carbon sink.

[0003] In agricultural production practices, increasing soil carbon content mainly relies on traditional measures such as straw return to the field and organic fertilizer application. These measures primarily enhance the soil carbon pool by directly increasing exogenous carbon, but they depend on continuous and large-scale material inputs and fail to effectively stimulate the potential for plant photosynthetic carbon input into the soil, making it difficult to achieve sustained and efficient carbon sequestration. Soil carbon sequestration depends not only on the direct input of exogenous organic carbon but also on the continuous input and effective transformation of plant photosynthetic carbon into the soil through rhizosphere exudates. However, under the stress conditions of highly acidic and nutrient-poor red soil, the distribution of plant photosynthetic carbon to the roots is inhibited, and the carbon use efficiency of rhizosphere microorganisms decreases, making it difficult for photosynthetic carbon to be effectively transformed and stably accumulated.

[0004] In recent years, microbial inoculants have been widely used in soil improvement as a biotechnology approach. In particular, functional microorganisms such as growth-promoting bacteria, nitrogen-fixing bacteria, and phosphate-solubilizing bacteria have been proven to improve the soil environment and promote crop growth. However, existing microbial inoculants mainly focus on promoting plant growth or improving nutrient utilization, lacking systematic research and application targeting soil carbon sequestration. Current technologies lack comprehensive technical solutions that can improve the rhizosphere environment, activate plant photosynthetic carbon input, and enhance microbial carbon conversion efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an application of a microbial agent for promoting carbon sequestration in red soil paddy fields. The microbial agent includes Rhodococcus rubrum, and a suspension of the microbial agent is inoculated into the rhizosphere of rice seedlings planted in red soil.

[0006] Preferred microbial agents include Rhodococcus rubrum and Pseudomonas aeruginosa.

[0007] Furthermore, the method for preparing the suspension of the bacterial agent is to mix equal volumes of Rhodococcus rubrum suspension and Pseudomonas aeruginosa suspension.

[0008] As a preferred method, the Rhodococcus erythropolis suspension was obtained by inoculating single colonies of Rhodococcus erythropolis isolated from acidic soil into Luria-Bertani (LB) medium and culturing in a shaking incubator until the cell density reached 2.3 × 10⁻⁶. 8 CFU•mL –1 Then, the LB medium was removed by centrifugation to collect the cells, and the collected cells were prepared into a suspension with sterile water.

[0009] The *Pseudomonas aeruginosa* suspension was obtained as follows: *Pseudomonas aeruginosa* isolated from acidic soil was inoculated as single colonies into Luria-Bertani (LB) medium and cultured in a shaking incubator until the cell density reached 2.3 × 10⁻⁶. 8 CFU•mL –1 Then, the LB medium was removed by centrifugation to collect the cells, and the collected cells were prepared into a suspension with sterile water.

[0010] Then, mix equal volumes of the above-obtained Rhodococcus rubrum suspension and Pseudomonas aeruginosa suspension to prepare a uniform suspension of the synthetic bacterial agent.

[0011] As a preferred option, the active ingredients of Luria-Bertani (LB) medium include 5 g / L yeast extract, 10 g / L tryptone, and 10 g / L sodium chloride.

[0012] As a preferred method, incubate at 28°C and 180 rpm for 24 hours in a shaking incubator.

[0013] As a preferred method, the centrifugation operation is to centrifuge in a disc centrifuge at 10000×g (10000 times the acceleration of gravity) for 5 minutes.

[0014] As a preferred method: 3 days after transplanting rice seedlings to red soil, inoculate the rhizosphere of each rice seedling with 25 mL of bacterial suspension.

[0015] The core mechanism by which the microbial agent in this invention promotes carbon sequestration in red soil paddy fields lies in constructing a regulatory pathway of "rhizosphere input activation - conversion efficiency enhancement - stable carbon pool formation." Specifically, this microbial agent improves the rhizosphere microenvironment, activates the input of plant photosynthetic carbon into the soil, significantly enhances the carbon use efficiency and conversion capacity (CUE) of the in-situ soil microbial community, promotes the accumulation of microbial-derived carbon, and further reshapes the molecular composition of dissolved organic matter (DOM), ultimately promoting the formation and accumulation of a stable carbon pool. This achieves full-process regulation from rhizosphere photosynthetic carbon input activation, CUE enhancement, microbial-derived carbon accumulation, DOM molecular structure reshaping to soil carbon pool increase. The *Pseudomonas aeruginosa* and *Rhodococcus rubrum* strains of this invention originate from acidic soil, are adapted to the red soil environment, and can realize green ecological agriculture. Furthermore, their combined action exhibits a significant "1+1>2" effect, demonstrating synergistic effects beyond those of single strains. The microbial community of this invention is operable, the strain expansion and cultivation process is simple and inexpensive, and it is convenient for field application. It can be prepared into a microbial agent and has good prospects for widespread application in red soil paddy fields. Attached Figure Description

[0016] Figure 1 This is a graph showing the difference in absolute quantification (16S rRNA gene abundance) of Rhodococcus erythropolis and Pseudomonas aeruginosa in the rhizosphere soil of rice cultivated in CK (uninoculated group) and SN (inoculated group with suspension of the synthetic bacterial agent of this application) during rice growth experiment.

[0017] Figure 2 This is a comparison chart of the SPAD values ​​(chlorophyll content) of rice cultivated in CK (uninoculated group), N (group inoculated with only the Rhodococcus erythropoietin suspension of this application), and SN (group inoculated with the synthetic bacterial agent suspension of this application) in a rice growth experiment.

[0018] Figure 3 These are comparative photographs of the root channels of rice cultivated in the CK (uninoculated group), N (group inoculated with only the Rhodococcus erythropoietin suspension of this application), and SN (group inoculated with the synthetic bacterial agent suspension of this application) groups during rice growth experiments.

[0019] Figure 4 This is a comparative graph showing the differences in rhizosphere exudate (metabolome) expression profiles between rice cultivated in CK (uninoculated group) and SN (inoculated group with suspension of synthetic bacterial agent of this application) in a rice growth experiment.

[0020] Figure 5This is a comparative graph of rhizosphere soil microbial biomass carbon in rice cultivated in rice growth trials in the following groups: CK (no inoculation with microbial agent), S (single inoculation with Pseudomonas aeruginosa suspension), N (single inoculation with Rhodococcus rubrum suspension of this application), ST (rice straw returned to the field), SN (inoculation with suspension of synthetic microbial agent of this application), and SN+ST (inoculation with suspension of synthetic microbial agent of this application + rice straw returned to the field).

[0021] Figure 6 This is a comparative graph showing the rhizosphere soil microbial carbon use efficiency of rice cultivated in rice growth experiments in the following groups: CK (no inoculation with microbial agent), S (single inoculation with Pseudomonas aeruginosa suspension), N (single inoculation with Rhodococcus rubrum suspension of this application), ST (rice straw returned to the field), SN (inoculation with suspension of synthetic microbial agent of this application), and SN+ST (inoculation with suspension of synthetic microbial agent of this application + rice straw returned to the field).

[0022] Figure 7 This is a comparison chart of the rhizosphere soil microbial carbon content of rice cultivated in CK (uninoculated group) and SN (inoculated group with suspension of synthetic microbial agent of this application) in a rice growth experiment.

[0023] Figure 8 This is a comparison chart showing the difference in the elemental ratio of remodeled dissolved organic matter (DOM) molecules in the rhizosphere soil of rice cultivated in CK (uninoculated group) and SN (inoculated group with suspension of synthetic microbial agent of this application) in a rice growth experiment.

[0024] Figure 9 This is a comparison chart of the proportion of remodeled dissolved organic matter (DOM) molecules in the rhizosphere soil of rice cultivated in CK (uninoculated group) and SN (inoculated group with suspension of synthetic microbial agent of this application) in a rice growth experiment.

[0025] Figure 10 This is a comparison chart of soil organic carbon (SOC) content at maturity in rice grown in CK (uninoculated group) and SN (inoculated group with suspension of the synthetic inoculant of this application) during rice growth trials. Detailed Implementation

[0026] The active ingredients of Luria-Bertani (LB) medium are 5 g / L yeast extract, 10 g / L tryptone, and 10 g / L sodium chloride. After preparation, the medium is placed into 500 mL Erlenmeyer flasks and sterilized at 121°C for 20 min.

[0027] Rhodococcus erythropolis (China General Microbiological Culture Collection Center, accession number: CGMCC No. 9611), isolated from acidic soil, was inoculated as a single colony into the aforementioned Luria-Bertani (LB) medium and cultured in a shaking incubator at 28°C and 180 rpm for 24 hours until the cell density reached 2.3 × 10⁻⁶ cells / year. 8 CFU•mL –1 Then, centrifuge the cells in a disc centrifuge at 10000×g (10000 times the acceleration due to gravity) for 5 minutes to remove the LB medium and collect the cells. Prepare a Red City Rhodococcus suspension (density approximately 2.3×10⁻⁶) using sterile water. 9 CFU•mL –1 );

[0028] Pseudomonas aeruginosa (CGMCC No. 34768, deposited at the China General Microbiological Culture Collection Center) isolated from acidic soil was inoculated as a single colony into the aforementioned Luria-Bertani (LB) medium and cultured in a shaking incubator at 28°C and 180 rpm for 24 hours until the cell density reached 2.3 × 10⁻⁶ cells / year. 8 CFU•mL –1 Then, centrifuge the cells in a disc centrifuge at 10000×g (10000 times the acceleration due to gravity) for 5 minutes to remove the LB medium and collect the cells. Prepare a Pseudomonas aeruginosa suspension (density approximately 2.3×10⁻⁶) with sterile water. 9 CFU•mL –1 );

[0029] Then, mix equal volumes of the above-obtained Rhodococcus rubrum suspension and Pseudomonas aeruginosa suspension to prepare a uniform suspension of the synthetic bacterial agent.

[0030] A single-factor randomized block design experiment was conducted on rice cultivation in the nutrient management plots of the Yingtan Red Soil Experimental Station. The rice variety was NG46, with a row spacing of 20 cm and a plant spacing of 20 cm. The fertilization background was a uniform NPK treatment. Six groups were set up: CK (no inoculation with microbial agent), N (inoculation with Rhodococcus hongchengensis suspension alone), S (inoculation with Pseudomonas aeruginosa suspension alone), SN (inoculation with suspension of the synthetic microbial agent alone), ST (rice straw return to the field), and SN+ST (inoculation with suspension of the synthetic microbial agent + rice straw return to the field). Each group involved 3 replicate plots (i.e., a total of 18 experimental plots, and there were no statistically significant differences in experimental conditions among the red soil experimental plots).

[0031] One day before transplanting rice seedlings, in the ST and SN+ST groups, chopped rice straw (approximately 5cm in length) was used as an exogenous carbon source, and applied at a rate of 500g / m². This rice straw was then evenly mixed into the topsoil layer (0-20cm below the soil surface) during tillage. Three days after transplanting the rice seedlings to the relevant plots, 25mL of the aforementioned *Rhodococcus rubrum* suspension was inoculated into the rhizosphere of each rice seedling in the N group, and in the S group... Inoculate the rhizosphere of the seedlings with 25 mL of the above-mentioned Pseudomonas aeruginosa suspension. In the SN group and SN+ST group, inoculate the rhizosphere of each rice seedling with 25 mL of the above-mentioned synthetic inoculant suspension. 60 days after inoculation (until the jointing stage), collect rice and its rhizosphere soil samples (a total of 18 experimental plots). Six samples are collected from each plot. The rhizosphere soil collection method is as follows: dig up the complete root system, collect the soil within 0-2 mm of the root surface, shake it gently and pass it through a 2 mm sieve.

[0032] The differences in absolute quantitative (16S rRNA gene abundance) of Rhodococcus erythropolis and Pseudomonas aeruginosa in the rhizosphere soil of rice cultivated in the above-mentioned rice growth experiment between CK (uninoculated group) and SN (inoculated group with suspension of the synthetic inoculum of this application) are shown in the appendix. Figure 1 As shown, the gene abundance of the two target strains in the SN treatment group was significantly higher than that in the CK group (P<0.001), confirming that the inoculated synthetic microbial community could successfully establish a microbial community and achieve stable colonization in the rhizosphere environment of red soil rice.

[0033] The differences in SPAD (chlorophyll content) of rice cultivated in the above-mentioned rice growth experiment among CK (uninoculated group), N (group inoculated with only the Rhodococcus erythropoietin suspension of this application), and SN (group inoculated with the synthetic inoculant suspension of this application) are shown in the attached figure. Figure 2 As shown, the N group, inoculated with Rhodococcus rubrum alone, showed a certain degree of improvement compared to the CK group, while the improvement in the SN treatment group was more significant. The difference in column height clearly demonstrates that the increase in the SN group relative to the CK group was significantly greater than the increase in the N group relative to the CK group. This indicates that the synthetic bacterial agent of this application has a significantly superior synergistic effect compared to single strains in promoting chlorophyll synthesis and enhancing photosynthetic capacity in rice leaves.

[0034] The differences in root morphology between the rice cultivated in the above-mentioned rice growth experiment in CK (uninoculated group), N (group inoculated with only the Rhodococcus erythropoietin suspension of this application), and SN (group inoculated with the synthetic inoculant suspension of this application) are shown in the appendix. Figure 3As shown: the root system of the CK group was relatively sparse, with fewer visible roots; in contrast, an increase in the number of roots was observed in the N group; while the root system of the SN treatment group was the most developed and dense, with a significant increase in the number of roots. In terms of root distribution density and breadth, the morphological differences between the SN and CK groups were far more pronounced than those between the N and CK groups.

[0035] The main differences in rhizosphere exudates (metabolome) expression changes between CK (uninoculated group) and SN (inoculated group with suspension of the synthetic inoculant of this application) in the above-mentioned rice growth experiment are shown in the attached figure. Figure 4 As shown: This indicator was detected using broad-targeted metabolomics technology. The figure displays the top 20 differentially expressed metabolites with the largest fold change. The SN treatment group significantly upregulated (Log2FC>0) secondary metabolites such as Cyclopiamide (alkaloid) and Colletotrichamide B, indicating that the synthetic microbial community activated the secondary metabolic signaling communication in the roots. At the same time, it significantly downregulated (Log2FC<0) primary carbon and nitrogen sources such as Glucosaminic acid and DL-Citrulline, which corresponds to the significant increase in microbial biomass.

[0036] The differences in microbial biomass carbon in the rhizosphere soil of rice cultivated in the above-mentioned rice growth experiments are shown in the appendix. These differences are as follows: CK (no inoculation with microbial agent), S (single inoculation with *Pseudomonas aeruginosa* suspension), N (single inoculation with *Rhodococcus rubrum* suspension as described in this application), ST (rice straw returned to the field), SN (inoculation with suspension of the synthetic microbial agent as described in this application), and SN+ST (inoculation with suspension of the synthetic microbial agent as described in this application + rice straw returned to the field). Figure 5 As shown:

[0037] MBC (Microbial Biomass Carbon) refers to soil microbial biomass carbon, specifically the total carbon within the tiny but highly active living microorganisms in the soil. In this invention, it reflects the portion of the carbon input from photosynthesis that is successfully assimilated and fixed within the microbial cells (equivalent to 'the flesh grown by the microorganisms'). A significant increase in MBC means that more carbon input into the soil is retained within the organisms, making it a core indicator for expanding the soil's active carbon pool.

[0038] Figure 5In the study, the SN treatment group increased the MBC content from 57 mg / kg in the CK group to 100 mg / kg, which was not only significantly better than the CK group, but also significantly higher than the two single-strain treatment groups S and N in terms of the increase relative to the CK group (P<0.05) (the increase in the SN treatment group was 43 mg / kg, while the increases in the S and N groups were 14 mg / kg and 12 mg / kg, respectively). This indicates that when Pseudomonas aeruginosa and Rhodococcus rubrum are used to intervene in rice seedlings in red soil at the same time, they have a synergistic effect that exceeds that of single strains, achieving a "1+1>2" effect.

[0039] Meanwhile, there was no statistically significant difference in the effects achieved between the SN group and the SN+ST group. This fully demonstrates that after intervention with the synthetic microbial agent of this application, the soil's own carbon sequestration potential was effectively mobilized, allowing the soil's active carbon pool to reach a near-saturation level, eliminating the need to rely on any external carbon source.

[0040] The differences in rhizosphere soil microbial carbon use efficiency (CUE) of rice cultivated in the above-mentioned rice growth trials among CK (uninoculated group), S (group inoculated with Pseudomonas aeruginosa suspension alone), N (group inoculated with Rhodococcus rubrum suspension as described in this application), ST (rice straw returned to the field), SN (group inoculated with suspension of the synthetic inoculum as described in this application), and SN+ST (group inoculated with suspension of the synthetic inoculum as described in this application + rice straw returned to the field) are shown in the appendix. Figure 6 As shown (the object of this index is rhizosphere soil; the detection method is...) 18 The O-H2O (oxygen-18 labeled water) isotope tracing method works on the principle that microorganisms assimilate oxygen from the water into their own DNA during growth. Therefore, by measuring the oxygen content in the DNA of rhizosphere soil microorganisms after culture... 18 The abundance of oxygen (O) can be used to calculate the growth rate of microorganisms. Combined with the respiration rate of microorganisms, carbon use efficiency (CUE) can be calculated using the formula: CUE = growth rate / (growth rate + respiration rate). This indicator reflects the ability of microorganisms in the rhizosphere soil to convert absorbed carbon sources into their own biomass.

[0041] Among them, the SN treatment group showed the highest CUE (labeled as a), which was significantly higher than the CK group (labeled as d) and the single-inoculation treatment groups S (labeled as bc) and N (labeled as b), indicating that the synthetic inoculant had a greater effect than single-inoculation (P<0.05).

[0042] It is noteworthy that the CUE (cd) value of the ST group, which only added straw, did not significantly increase. This is consistent with the metabolic trade-off mechanism that "straw, as a persistent exogenous carbon source, requires microorganisms to consume more ATP to synthesize extracellular enzymes for decomposition, leading to increased respiration loss." In contrast, the SN and N groups of this invention, by alleviating rhizosphere environmental stress, promoted the efficient assimilation of readily available rhizosphere photosynthetic carbon by microorganisms, thereby achieving higher carbon conversion efficiency. Furthermore, in the SN+ST group (labeled b), the CUE value did not exceed that of the SN group (labeled a), further confirming that "inoculation with synthetic inoculants only" is an effective technical path for achieving efficient soil carbon conversion.

[0043] The differences in the ratio of soil microbial carbon to soil organic carbon between rice grown in the above-mentioned rice growth experiment in CK (uninoculated group) and SN (inoculated group with suspension of the synthetic microbial agent of this application) are shown in the attached figure. Figure 7 As shown, the soil microbial carbon content in the SN treatment group was approximately 1.8 g / kg, significantly higher than the 1.2 g / kg in the CK group, with an average increase of 50% (P<0.001). "Microbial carbon" belongs to stable organic carbon.

[0044] The differences in the elemental ratios of remodeled dissolved organic matter (DOM) in the rhizosphere soil of rice cultivated in the above-mentioned rice growth experiment between CK (uninoculated group) and SN (inoculated group with suspension of the synthetic inoculant of this application) are shown in the attached figure. Figure 8 As shown, the H / C ratio (hydrogen-carbon ratio) and N / C ratio (nitrogen-carbon ratio) of the SN treatment group were significantly higher than those of the CK group (P<0.01), while the O / C ratio (oxygen-carbon ratio) was significantly lower than that of the CK group (P<0.05), indicating that the chemical stability of DOM mediated by the synthetic microbial community was significantly enhanced (soluble organic matter was extracted from rhizosphere soil by water extraction and then analyzed by ultra-high resolution mass spectrometry (FT-ICR MS)).

[0045] The differences in the proportions of remodeled dissolved organic matter (DOM) macromolecules in the rhizosphere soil of rice cultivated in the above-mentioned rice growth experiment between CK (uninoculated group) and SN (inoculated group with suspension of the synthetic microbial agent of this application) are shown in the appendix. Figure 9 As shown, the lignin content in the SN treatment group was significantly lower than that in the CK group (P<0.001). Meanwhile, the protein content in the SN treatment group increased from about 20% to about 35% compared to the CK group (P<0.01), the lipid content in the SN treatment group increased from about 15% to about 25% compared to the CK group (P<0.05), and the amino sugar content in the SN treatment group was also significantly higher than that in the CK group (P<0.05).

[0046] The differences in soil organic carbon content at maturity between rice grown in the above-mentioned rice growth experiment in the CK (uninoculated group) and SN (inoculated group with suspension of the synthetic inoculant of this application) are shown in the attached figure. Figure 10 As shown, the soil organic carbon content in the SN treatment group was approximately 8.2 g / kg, which was significantly higher than that in the CK group (6.8 g / kg) (P<0.001).

[0047] pass Figures 8 to 10 It is evident that the intervention of the synthetic microbial agent proposed in this application during the growth process of rice can better stimulate the rapid turnover of in-situ microorganisms in the planting soil, which is conducive to the accumulation of SOC and microbial source carbon, and the molecular structure stability of DOM is also higher.

Claims

1. An application of a microbial agent to promote carbon sequestration in red soil paddy fields, characterized in that: The application involves inoculating a suspension of the microbial agent into the rhizosphere of rice seedlings planted in red soil, wherein the microbial agent includes Rhodococcus rubrum.

2. The application of the microbial agent as described in claim 1 for promoting carbon sequestration in red soil paddy fields, characterized in that: The bacterial agent includes Rhodococcus rubrum and Pseudomonas aeruginosa.

3. The application of the microbial agent as described in claim 2 for promoting carbon sequestration in red soil paddy fields, characterized in that: The method for preparing the suspension of the bacterial agent is to mix equal volumes of Rhodococcus rubrum suspension and Pseudomonas aeruginosa suspension.

4. The application of the microbial agent as described in claim 3 for promoting carbon sequestration in red soil paddy fields, characterized in that: The method for preparing the Rhodococcus rubrum suspension is as follows: Rhodococcus rubrum isolated from acidic soil is inoculated into Luria-Bertani medium in the form of single colonies, and cultured in a shaking incubator until the cell density reaches 2.3 × 10⁻⁶. 8 CFU•mL –1 Then, the LB medium was removed by centrifugation to collect the cells, and the collected cells were prepared into the Rhodococcus rubella suspension using sterile water. The method for preparing the *Pseudomonas aeruginosa* suspension is as follows: *Pseudomonas aeruginosa* isolated from acidic soil is inoculated into Luria-Bertani medium as single colonies and cultured in a shaking incubator until the cell density reaches 2.3 × 10⁻⁶. 8 CFU•mL –1 Then, the LB medium was removed by centrifugation to collect the cells, and the collected cells were prepared into the Pseudomonas aeruginosa suspension with sterile water.

5. The application of the microbial agent as described in claim 4 for promoting carbon sequestration in red soil paddy fields, characterized in that: The active ingredients of the Luria-Bertani medium include 5 g / L yeast extract, 10 g / L tryptone, and 10 g / L sodium chloride.

6. The application of the microbial agent as described in claim 4 for promoting carbon sequestration in red soil paddy fields, characterized in that: Incubate at 28°C and 180 rpm for 24 hours in the shaking incubator.

7. The application of the microbial agent as described in claim 4 for promoting carbon sequestration in red soil paddy fields, characterized in that: The centrifugation operation is to centrifuge for 5 minutes in a disc centrifuge at 10,000 times the acceleration of gravity.

8. The application of the microbial agent as described in claim 1 or 2 for promoting carbon sequestration in red soil paddy fields, characterized in that: Three days after the rice seedlings were transplanted to the red soil, 25 mL of the bacterial agent suspension was inoculated into the rhizosphere of each rice seedling.

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