Method for promoting deep plowing, returning and decomposing of winter slack weeds and accumulation of organic carbon in soil

Abstract

The invention relates to the technical field of agriculture, and discloses a method for promoting deep plowing and field returning decomposition of winter slack weeds and soil organic carbon accumulation, the method comprises the following steps: S1, using target weeds as a unique carbon source, selectively culturing from field soil, and screening to obtain dominant indigenous microbial florae with specific efficient decomposition capability on the weeds; s2, taking the screened flora as an active core, and coating the active core and an internal functional component for promoting decomposition and stabilizing a product in a responsive shell; an external trigger module is fixed on the surface of the shell and can generate a signal in an enzymatic manner after being in contact with weeds to trigger release of the effective load; s3, the prepared synergistic microcapsules are applied to the earth surface of a field, deep ploughing operation is conducted immediately, and the microcapsules and weeds are fully mixed in soil to start the decomposition process. By means of the synergistic microcapsule with the external trigger module, targeted and efficient decomposition of weeds is achieved, and decomposition products are synchronously converted into stable organic carbon.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, specifically to a method for promoting the deep plowing and decomposition of winter fallow weeds and the accumulation of soil organic carbon. Background Technology

[0002] During the winter fallow period, fallow weeds in farmland are a common biomass resource. How to effectively treat these weeds and transform them into beneficial soil resources rather than agricultural waste is an important technological focus in modern sustainable agriculture. Achieving on-site resource utilization of fallow weeds not only relates to the growth environment of the next season's crops but also has a direct impact on maintaining and improving the long-term fertility and carbon pool levels of arable land.

[0003] For the management of winter fallow weeds, existing technologies mainly offer several solutions. Among these, the most direct and widely used is mechanical tillage, which involves turning surface weeds directly into the soil through plowing or rotary tillage. Additionally, there is a technical approach of using chemical herbicides to remove weeds first, followed by subsequent cultivation. Regarding biotechnology applications, some technologies have attempted to develop and apply microbial agents, using selected microbial strains capable of decomposing plant straw, applied to the field through spraying or mixing with organic fertilizer to promote the decomposition of weeds.

[0004] While existing technologies have achieved weed return to the field to some extent, several shortcomings remain: The decomposition rate and efficiency are generally low. This is primarily because winter fallow weeds typically have a high carbon-to-nitrogen ratio. During decomposition in the soil, microorganisms compete with the soil environment and future crops for limited nitrogen, thus inhibiting their own decomposition activity. Furthermore, conventional microbial agents are easily diluted in the complex soil environment and struggle to precisely target the weed surface, hindering their effectiveness. Secondly, existing technologies do not adequately address the efficient conversion of carbon from weeds into stable soil organic carbon. The active organic molecules produced by weed decomposition are easily remineralized into carbon dioxide by other soil microorganisms before being fixed into stable organic-inorganic complexes. The existing decomposition process and the organic carbon stabilization process are spatially and temporally disconnected, lacking effective coupling techniques. Furthermore, the action process of existing biological agents lacks controllability. Once their active components are applied to the soil, their release and action are completely subject to uncontrollable environmental factors. The decomposition process cannot be initiated based on whether or not the target weeds come into contact with them, which to some extent leads to resource waste and reduces the certainty of the technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, as well as the accumulation of soil organic carbon. This method solves the problems of slow decomposition rate, lack of targeted action of microorganisms, and low efficiency of converting weed carbon into stable soil organic carbon in existing winter fallow weed returning techniques.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon. The method first involves a microbial community screening step. This step uses the substrate powder of winter fallow weeds from the target field as the sole carbon source, and selectively cultivates the microorganisms under this specific condition. Specifically, soil samples from the target field are inoculated into a liquid culture medium using the weed substrate powder as the carbon source, and subjected to multiple generations of enrichment culture to amplify microorganisms highly adaptable to this specific substrate.

[0007] Subsequently, the enriched culture medium was spread onto a solid culture medium containing the same carbon source. By observing and measuring the size of the hydrolysis zone formed around the colony due to substrate decomposition, the colonies with the strongest decomposition ability were screened and purified, ultimately yielding a dominant indigenous microbial community with highly efficient decomposition capabilities against the target winter fallow weeds.

[0008] Next, the preparation step of the synergistic microcapsule is performed. This step aims to formulate the screened microbial community into a multifunctional, programmed-response formulation. Structurally, the synergistic microcapsule comprises, from the inside out: an active core, an internal functional component, a responsive shell, and an external triggering module.

[0009] The active core is a dormant microbial powder prepared by liquid fermentation culture (temperature 28-35℃, time 48-72 hours) and subsequent freeze-drying of the obtained dominant indigenous microbial community.

[0010] The internal functional components and the active core together constitute the payload, which includes one or more of the following substances: Slow-release nutrient substrate: Its function is to provide microorganisms with the necessary, precisely calculated nitrogen supplement during the initial stages of decomposition. The required amount of nitrogen to be added is calculated using the following formula: ; In the formula, The estimated dry weight of weed biomass within a single treatment unit; The average carbon content of weed biomass; The average nitrogen content of weed biomass; The optimal target carbon-nitrogen ratio for microbial decomposition was set.

[0011] N-acylhomoserine lactone: As a quorum sensing signaling molecule, its function is to induce synchronous and efficient synergistic decomposition behavior in the entire microbial community when it reaches a certain concentration after being released from microorganisms.

[0012] Organic carbon stabilizing promoters: These can specifically be montmorillonite, bentonite, and / or vermiculite. Physically, these components possess a large specific surface area and surface charge. Their function is to form organic-inorganic complexes with the resulting small organic molecules and microbial residues after microbial decomposition of weeds. Through physical protection, these complexes prevent remineralization, thereby promoting the long-term stable accumulation of organic carbon.

[0013] The responsive outer shell is made of a material that is dually responsive to moisture in the soil and specific chemical signals, such as chitosan and / or sodium alginate. Its function is that after initial swelling upon contact with soil moisture, its structure undergoes an irreversible change upon receiving a chemical signal generated by an external trigger module, thereby releasing the internal payload.

[0014] The external triggering module is fixed to the outer surface of the responsive shell. This module consists of immobilized polysaccharide-degrading enzymes (such as cellulase or hemicellulase). Its mechanism of action is as follows: when the co-capsule comes into contact with winter fallow weeds, the enzymes on this module immediately degrade the cell wall components (cellulose or hemicellulose) of the weeds. The product of this enzymatic reaction is a small-molecule organic acid. These small-molecule organic acids are the chemical signals that trigger changes in the structure of the responsive shell.

[0015] Based on the above components, the components of the synergistic microcapsule, by weight ratio, may include: 10-30 parts of an active core; internal functional components, including 30-80 parts of a sustained-release nutrient matrix, 0.01-0.5 parts of N-acylhomoserine lactone, and 20-60 parts of an organic carbon stabilizing promoter; 5-15 parts of a responsive shell; and 0.1-1.0 parts of a polysaccharide-degrading enzyme in an external triggering module immobilized on the outer surface of the responsive shell.

[0016] The preparation process is as follows: First, an active core is prepared; then, using a multi-stage fluidized bed, a suspension containing internal functional components is coated onto the active core at a material temperature of 30-40℃; continuing at a material temperature of 40-50℃, a solution of a responsive shell is coated onto the outer layer; finally, using glutaraldehyde as a crosslinking agent, polysaccharide degrading enzymes are immobilized on the outer surface of the responsive shell via covalent coupling at 4-25℃ to form an external triggering module.

[0017] Finally, the process of returning the microcapsules to the field for decomposition and organic carbon accumulation is carried out. This step involves evenly applying the aforementioned synergistic microcapsules to the surface of fields with winter fallow weeds at a predetermined application rate. The application rate is determined according to the following formula: ; In the formula, The dosage per unit area of ​​the synergistic microcapsule; The initial effective density of microorganisms expected to be achieved in weed-rich areas; The total mass of the target soil region per unit area where the synergistic microcapsules act; The concentration of active microorganisms in the synergistic microcapsule product.

[0018] After application, deep tillage is carried out using a deep plow or subsoiler to a depth of 20-40 cm. The purpose of this operation is to thoroughly and tightly mix the surface synergistic microcapsules with winter fallow weeds and incorporate them into the soil, creating the necessary physical contact conditions for subsequent programmed decomposition and organic carbon conversion processes.

[0019] This invention provides a method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, as well as the accumulation of soil organic carbon. It has the following beneficial effects: 1. This invention utilizes the target weed itself as the sole carbon source for specific screening, thereby obtaining a dominant indigenous microbial community with naturally efficient decomposition capabilities for that weed. Simultaneously, a designed external triggering module ensures that the synergistic microcapsules only release their active cores through enzymatic reactions upon physical contact with the target weed. The combination of these two technical features allows for the precise delivery of highly efficient microbial communities to the target site, improving weed decomposition efficiency and the method's targeting specificity.

[0020] 2. The synergistic microcapsules of this invention contain N-acylhomoserine lactone for accelerated decomposition and a slow-release nutrient matrix, as well as one or more of montmorillonite, bentonite, and / or vermiculite as organic carbon stabilizing promoters. This structural design allows the stabilizer to immediately adsorb and complex the decomposition products in the same microenvironment where microorganisms efficiently decompose the organic matter produced by weeds, forming a stable organic-inorganic complex. This tightly couples the decomposition and stabilization processes in time and space, improving the conversion efficiency of weed carbon to stable soil organic carbon.

[0021] 3. The synergistic microcapsules designed in this invention have a clearly defined programmed response mechanism. Their responsive shell design requires both soil moisture and a chemical signal generated by an external trigger module to fully release the effective payload. This design avoids premature or random failure of the formulation in the soil, ensuring that its core function is only activated under preset conditions of mixing with weeds, thus making the initiation and progress of the entire decomposition process highly controllable. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a comparison curve of weed decomposition rates in each treatment group in Test Example 1 of the present invention; Figure 3 This is a comparative bar chart showing the content and composition of soil organic carbon in each treatment group in Test Example 2 of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1 - Appendix Figure 3 : Preparation Example 1: This preparation example describes the process for preparing dormant mycelial powder of dominant indigenous microbial communities.

[0025] Preparation of weed substrate: During the winter fallow period, collect typical winter fallow weeds from the target field, such as Galium aparine and Alopecurus aequalis. Wash the collected weeds, dry them in an oven at 60°C to constant weight, then crush them using a plant pulverizer and sieve them through a 60-mesh sieve to obtain uniform weed substrate powder.

[0026] Enrichment and Screening: Prepare a liquid selective culture medium containing, per 1000 mL of deionized water: 10 g weed substrate powder, 2 g (NH4)2SO4, 1 g K2HPO4, 0 g MgSO4·7H2O, and 0 g NaCl, adjusting the pH to 7.0. Take 10 g of topsoil from the target field and inoculate it into 100 mL of this medium, incubating for 3 days at 30°C and 150 rpm on a shaker. Subsequently, transfer 1% of the culture solution to fresh medium, repeating this transfer operation 4 times to complete the enrichment.

[0027] Isolation and purification: The final enrichment solution was serially diluted and spread onto solid selective medium supplemented with 1.5% agar. After incubation at 30℃ for 3-5 days, colonies were observed. Colonies with clear and largest hydrolysis zones were selected and purified by streak plating to obtain multiple highly efficient decomposing bacteria and fungi. Five selected bacterial strains and three selected fungal strains were mixed in equal proportions to form the dominant indigenous microbial community.

[0028] Expanding the culture and preparing the bacterial powder: The above-mentioned complex microbial community was inoculated into liquid fermentation medium (each 1000 ml contains: 10 g peptone, 5 g yeast extract, and 10 g glucose) and cultured in a fermenter at 30°C and pH 7.0 for 60 hours. After the culture was completed, the bacterial cells were collected by centrifugation and washed with sterile phosphate buffer. The bacterial cells were mixed with a cryoprotectant solution containing 10% skim milk powder and 5% trehalose at a 1:1 ratio, pre-frozen at -50°C for 4 hours, and then dried in a vacuum freeze dryer for 36 hours to finally obtain a powdered dormant bacterial powder of the dominant indigenous microbial community.

[0029] Preparation Example 2: This preparation example describes the process for preparing a mixture of internal functional components for synergistic microcapsule coating.

[0030] Modified starch was selected as the main slow-release nutrient matrix carrier, urea as the nitrogen source, 200-mesh montmorillonite powder as the organic carbon stabilizer, and commercially available N-acylhomoserine lactone (AHL) powder as the quorum sensing control module. The above components were placed in a V-type mixer and dry-mixed at room temperature for 30 minutes until a uniform powder mixture with consistent appearance and color was formed. This mixture was then sealed for later use. This mixture can serve as the internal functional component coating the active core.

[0031] Preparation Example 3: This preparation example describes the process for preparing a responsive shell coating solution for the outermost layer of synergistic microcapsules.

[0032] Accurately weigh chitosan powder (90% degree of deacetylation) and slowly add it to a 1% (v / v) aqueous solution of acetic acid while continuously stirring mechanically. Stir continuously for 4 hours at room temperature (25°C) until the chitosan is completely dissolved, forming a clear, transparent, and viscous solution with a concentration of 2% (w / v) free of insoluble particles. Filter this solution through a 0.45-micron filter membrane to obtain the responsive shell coating solution, and seal it for later use.

[0033] Example 1: Formulation: The synergistic microcapsules of this embodiment, by weight ratio, include: Active core (dormant bacterial powder of dominant indigenous microbial community obtained in Preparation Example 1): 20 parts; The internal functional component (the mixture prepared in Example 2) contains 55 parts of slow-release nutrient matrix, 0.25 parts of N-acylhomoserine lactone, and 40 parts of organic carbon stabilizer. Responsive shell (formed from the solution of Preparation Example 3): 10 parts; Polysaccharide-degrading enzyme (commercially purchased cellulase) in the external trigger module: 0.55 parts.

[0034] Preparation steps: 20 portions of the dormant bacterial powder obtained in Preparation Example 1 were used as crystal nuclei and placed in a multi-stage fluidized bed coating machine.

[0035] A mixture of internal functional components, including a slow-release nutrient matrix, N-acyl homoserine lactone, and an organic carbon stabilizer, was prepared into a suspension. The suspension was then spray-coated while the fluidized bed material temperature was maintained at 35°C until the coating amount reached the set value.

[0036] Using the responsive shell coating solution prepared in Preparation Example 3, a second layer of spray coating was performed while maintaining the fluidized bed material temperature at 45°C until the coating amount reached the set value.

[0037] The obtained double-coated synergistic microcapsules were collected and activated with 1.25% glutaraldehyde solution at 25°C for 1.5 hours. After washing, they were immersed in cellulase solution and subjected to a covalent coupling reaction at 15°C for 8 hours. After the reaction was completed, the synergistic microcapsules were filtered, washed, and dried at low temperature to obtain the final product.

[0038] Usage steps: Calculate the application rate of the synergistic microcapsules prepared in this embodiment to achieve the preset initial effective microbial density in the soil, and evenly spread the application rate on the surface of the target field with winter fallow weeds. After application, use a deep plow to deeply plow the field to a depth of 30 cm to mix the synergistic microcapsules with the weeds in the soil.

[0039] Example 2: Formulation: The synergistic microcapsules of this embodiment, by weight ratio, include: Active core (dormant bacterial powder of dominant indigenous microbial community obtained in Preparation Example 1): 10 parts; The internal functional component (the mixture prepared in Example 2) contains 30 parts of slow-release nutrient matrix, 0.01 parts of N-acylhomoserine lactone, and 20 parts of organic carbon stabilizer. Responsive shell (formed from the solution of Preparation Example 3): 5 parts; Polysaccharide-degrading enzyme (commercially sourced cellulase) in the external trigger module: 0.1 parts.

[0040] Preparation steps: Ten portions of the dormant bacterial powder prepared in Preparation Example 1 were used as crystal nuclei.

[0041] The internal functional components were coated under the condition that the fluidized bed material temperature was maintained at 30°C.

[0042] The responsive shell was coated under the condition that the fluidized bed material temperature was maintained at 40°C.

[0043] The obtained double-coated synergistic microcapsules were collected and activated with 0.5% glutaraldehyde solution. Subsequently, they were immersed in cellulase solution and covalently coupled at 4°C. After the reaction, post-processing was performed as in Example 1 to obtain the final product.

[0044] Usage steps: Calculate the application rate of the synergistic microcapsules prepared in this embodiment to achieve the preset initial effective microbial density in the soil, and evenly spread the application rate on the surface of the target field with winter fallow weeds. After application, use a deep plow to deeply plow the field to a depth of 20 cm to mix the synergistic microcapsules with the weeds in the soil.

[0045] Example 3: Formulation: The synergistic microcapsules of this embodiment, by weight ratio, include: Active core (dormant bacterial powder of dominant indigenous microbial community prepared in Example 1): 30 parts; The internal functional component (the mixture prepared in Example 2) contains 80 parts of slow-release nutrient matrix, 0.5 parts of N-acylhomoserine lactone, and 60 parts of organic carbon stabilizer. Responsive shell (formed from the solution of Preparation Example 3): 15 parts; Polysaccharide-degrading enzyme (commercially sourced cellulase) in the external trigger module: 1.0 part.

[0046] Preparation steps: Thirty portions of the dormant bacterial powder prepared in Preparation Example 1 were used as crystal nuclei.

[0047] The internal functional components were coated under the condition that the fluidized bed material temperature was maintained at 40°C.

[0048] The responsive shell was coated under the condition that the fluidized bed material temperature was maintained at 50°C.

[0049] The obtained double-coated synergistic microcapsules were collected and activated with 2.0% glutaraldehyde solution. Subsequently, they were immersed in cellulase solution and covalently coupled at 25°C. After the reaction, post-processing was performed as in Example 1 to obtain the final product.

[0050] Usage steps: Calculate the application rate of the synergistic microcapsules prepared in this embodiment to achieve the preset initial effective microbial density in the soil, and evenly spread the application rate on the surface of the target field with winter fallow weeds. After application, use a deep plow to deeply plow the field to a depth of 40 cm to mix the synergistic microcapsules with the weeds in the soil.

[0051] Comparative Example 1: Compared with Example 1, the difference is that synergistic microcapsule preparation was not performed. Instead, all components of the formulation in Example 1 (dormant bacterial powder, internal functional components, and polysaccharide degrading enzymes) were simply physically mixed and applied directly as a powder formulation. All other aspects were the same.

[0052] Comparative Example 2: Compared with Example 1, the difference is that the step of immobilizing the polysaccharide-degrading enzyme on the outer surface of the responsive shell was omitted in the preparation steps of the synergistic microcapsules, that is, the resulting synergistic microcapsules do not have an external triggering module. All other steps are the same.

[0053] Comparative Example 3: Compared with Example 1, the difference is that the internal functional components of the synergistic microcapsule formulation do not contain montmorillonite as an organic carbon stabilizing promoter. All else is the same.

[0054] Comparative Example 4: Compared with Example 1, the difference is that no formulation was applied, and only mechanical deep plowing was carried out on the surface of the target field with the same winter fallow weeds. Everything else was the same.

[0055] Test Example 1: This test case aims to quantitatively determine and compare the effects of Examples 1-3 and Comparative Examples 1-4 on the decomposition rate of winter fallow weeds under specific conditions.

[0056] Experimental steps: Experimental preparation: A pot experiment was conducted. Plastic culture pots with an inner diameter of 30 cm and a height of 40 cm were used, and each pot contained 15.0 kg of air-dried soil collected from the target field. The experiment consisted of 7 treatment groups: Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. Each treatment had 3 replicates.

[0057] Substrate bag preparation: Collected and dried winter fallow weeds (substrate) are cut into segments approximately 5 cm in length. 10 grams of weed segments are accurately weighed using an electronic balance and placed into nylon mesh bags measuring 20 cm × 20 cm with a mesh size of 0.5 mm. The bag opening is then sealed with nylon thread.

[0058] Experimental treatment and placement: According to the settings of each treatment group, the preparations of Examples 1-3 and Comparative Examples 1-3 were evenly mixed into the surface soil of the corresponding potted plants according to the equivalent active microbial application rate (calculated based on the concentration of microbial powder). Subsequently, a prepared weed substrate mesh bag was buried in the soil layer 15 cm deep in the center of each potted plant. Comparative Example 4 served as a blank control, without the application of any preparations, only the substrate mesh bag was buried in the soil.

[0059] Culture and Sample Collection: All potted plants were placed in a natural light greenhouse for 90 days, during which water was replenished periodically by weighing to maintain soil moisture content at 60% of field capacity. On days 15, 30, 60 and 90 after the start of culture, one nylon mesh bag was randomly selected from each of the three replicate potted plants in each treatment group.

[0060] Data Measurement: Carefully rinse the surface of the removed nylon mesh bags to remove the soil with clean water. Cut open the mesh bags and transfer the weed residue inside into a pre-weighed aluminum box. Place the aluminum box in a 65℃ constant temperature forced-air drying oven for 48 hours until constant weight. After cooling in a desiccator, weigh and record the dry weight of the weed residue. Calculate the weed decomposition rate using the formula: Decomposition rate (%) = (Initial dry weight - Dry weight at sampling) / Initial dry weight × 100%.

[0061] Experimental data: Table 1: Weed decomposition rate (%) of each treatment group at different time points From Table 1, we can obtain: The treatment groups treated with the synergistic microcapsules prepared in Examples 1, 2, and 3 showed higher weed decomposition rates at all measurement time points than all comparative treatment groups. This indicates that using a dominant indigenous microbial community with high decomposition capabilities, selected through specific carbon source screening, as the active core, supplemented by the slow-release nutrient matrix provided by the internal functional components, can provide sufficient microbial germplasm and regulated carbon-nitrogen ratio conditions for the weed decomposition process, thereby improving the decomposition rate of the target weeds. Compared with Comparative Example 4, which only underwent mechanical compaction, the decomposition rate of the example treatment groups was more than twice as high at 90 days, demonstrating the direct effect of this method on accelerating the decomposition of weeds returned to the field.

[0062] Comparative Example 2, lacking an external triggering module, relied on the passive swelling of the outer shell for payload release, a slower and non-targeted process, resulting in a lower decomposition rate than Example 1. In Example 1, the external triggering module, upon physical contact with weeds, generates a chemical signal through an enzymatic reaction, causing a structural change in the responsive shell and rapidly releasing the active core, achieving immediate and concentrated release at the target site. Comparative Example 1, with its simple physical mixing of all components, exhibited even lower decomposition efficiency. This confirms that the shell structure of the synergistic microcapsule provides necessary physical protection for the internal active microbial flora and functional components in the soil environment, preventing premature inactivation or dilution before they can exert their effects.

[0063] After the synergistic microcapsules are applied to the soil and mixed with weeds, an external trigger module first identifies the weeds and generates a signal. Subsequently, the responsive shell receives the signal and releases the payload. Finally, under optimized nutrient conditions, a high concentration of active microorganisms rapidly decomposes the weeds. This series of continuous and interconnected steps ensures the maximization of the decomposition function, constituting the key technical feature that distinguishes this solution from existing technologies.

[0064] Test Example 2: This test case aims to determine and compare the effects of different treatments on the total organic carbon content of the soil and the distribution of organic carbon in different stable components 90 days after weed decomposition.

[0065] Experimental steps: Soil Sample Collection and Preparation: On day 90 of the pot experiment in Test Example 1, after removing the nylon mesh bags, approximately 500 grams of soil samples from the 0-20 cm soil layer were collected from each pot using a multi-point mixing method. The collected soil samples were placed in a cool, ventilated place to air dry naturally. After removing plant roots and gravel, the samples were ground in an agate mortar and pestle, and then passed through a 2 mm mesh sieve. After thorough mixing, the samples were bagged and ready for use.

[0066] Total organic carbon content determination: The potassium dichromate oxidation-external heating method was used. Accurately weigh 0.5 g of sieved soil sample and place it in a hard glass test tube. Add 5 mL of 1.0 mol / L potassium dichromate-sulfuric acid solution and heat in an oil bath at 180°C for 5 minutes for digestion. After cooling, transfer the digest to a 250 mL Erlenmeyer flask. Titrate the remaining potassium dichromate with 0.2 mol / L ferrous sulfate standard solution. Calculate the total organic carbon content in the soil based on the amount of ferrous sulfate consumed.

[0067] Determination of stable organic carbon components: The physical density grouping method was used. 10 g of air-dried soil sample was accurately weighed and placed in a 50 mL centrifuge tube, and 30 mL of sodium iodide (NaI) solution with a density of 1.70 g / cm³ was added. The sample was dispersed in an ultrasonic cleaner for 10 minutes, and then centrifuged at 4000 rpm for 15 minutes. After centrifugation, the supernatant and suspended light organic carbon (LFOM) were aspirated using a vacuum pump and collected by filtration through a 0.45 μm filter membrane. The sediment at the bottom of the tube (containing mineral-bound recombinant organic carbon, HFOM) was repeatedly washed with deionized water and centrifuged to remove sodium iodide. The collected light and recombinant components were dried, weighed, and their carbon content was determined using the potassium dichromate oxidation method described above.

[0068] Data calculation: Based on the measurement results, the total organic carbon (SOC) content (g / kg) and recombinant organic carbon (HFOM-C) content (g / kg) of soil in each treatment were calculated, and the proportion of recombinant organic carbon in total organic carbon (%) was calculated.

[0069] Experimental data: Table 2: Total organic carbon content and recombinant organic carbon distribution in soil of each treatment group From Table 2, we can obtain: The total organic carbon content of the soil in treatment groups 1, 2, and 3 was higher than that in all comparative examples. This result corresponds to the high decomposition rate observed in test example 1, indicating that more weed biomass carbon was converted and input into the soil after treatment with this technical solution. Compared with comparative example 4, which only underwent incorporation, the total organic carbon increase in the treatment groups of the examples was significant, confirming the effectiveness of this method in improving soil carbon sequestration function.

[0070] The comparison between Comparative Example 3 and Example 1 clearly reveals the mechanism of action of the organic carbon stabilizing promoter. Although the total organic carbon content of Comparative Example 3 increased due to efficient decomposition due to the lack of a stabilizer, its proportion of recombinant organic carbon was the lowest among all treatments. This indicates that in the absence of a stabilizing promoter, even if weeds are rapidly decomposed, the newly generated active organic matter is difficult to effectively combine with soil minerals, and most of it still exists in an unstable light compound form. In contrast, in Example 1, the stabilizers such as montmorillonite contained in the microcapsules, due to their large specific surface area and surface charge, can capture and adsorb newly generated soluble organic molecules and microbial residues nearby while microorganisms decompose weeds. By forming an organic-inorganic complex, this part of the carbon is fixed in the recombinant organic carbon (HFOM), thereby improving the stability of the newly generated organic carbon.

[0071] The proportion of recombined organic carbon in both Comparative Example 1 (physical mixing) and Comparative Example 2 (without trigger module) showed no significant increase, indicating that simply adding the components to the soil cannot achieve effective carbon stabilization. The microcapsule structure in the examples, through a programmed release mechanism, ensures a high degree of temporal and spatial synchronization and synergy between microbial decomposition and the physical adsorption of the stabilizer. This decomposition-stabilization coupling environment created at the microscale is the key difference from traditional technologies. It effectively protects activated carbon before it is remineralized, thereby achieving a dual improvement in the quantity and quality of soil organic carbon.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, characterized in that, The method includes the following steps: S1. Screening of microbial communities: Using the substrate powder of winter fallow weeds in the target field as a carbon source, the dominant indigenous microbial communities with efficient decomposition ability for the winter fallow weeds are screened from the soil of the target field through selective culture. S2. Preparation of synergistic microcapsules: The dominant indigenous microbial community is used as the active core, and together with internal functional components used to promote the decomposition activity of the active core and to stabilize its decomposition products, they constitute the payload; the payload is encapsulated in a responsive shell; an external triggering module is fixed on the outer surface of the responsive shell, which is used to generate a chemical signal that can trigger the responsive shell to release the payload through an enzymatic reaction when in contact with the winter fallow weeds; S3. The implementation of returning the microcapsules to the field for decomposition and organic carbon accumulation involves applying the prepared synergistic microcapsules to the surface of the field where the winter fallow weeds grow, followed by deep plowing to mix the synergistic microcapsules with the winter fallow weeds in the soil.

2. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... The screening of the microbial community includes the following steps: soil samples from the target field are inoculated into a liquid culture medium with the substrate powder of the winter fallow weeds as the carbon source for multi-generation enrichment culture, and then the enriched liquid is spread on a solid culture medium containing the same carbon source, and the dominant indigenous microbial community is screened and purified according to the size of the hydrolysis zone around the colony.

3. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the preparation step of the synergistic microcapsule, the external triggering module is a module with an immobilized polysaccharide degrading enzyme, the enzymatic reaction is the degradation of cellulose or hemicellulose of the winter fallow weed by the polysaccharide degrading enzyme, and the chemical signal is the small molecule organic acid produced by the degradation.

4. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the preparation step of the synergistic microcapsule, the internal functional component includes N-acylhomoserine lactone, which is used to pre-activate the synergistic decomposition behavior of the dominant indigenous microbial community.

5. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the preparation step of the synergistic microcapsules, the internal functional component includes one or more of montmorillonite, bentonite and / or vermiculite as organic carbon stabilizing promoters.

6. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the preparation step of the synergistic microcapsules, the material of the responsive shell is chitosan and / or sodium alginate, which are dually responsive to moisture in the soil and the chemical signals.

7. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the preparation step of the synergistic microcapsules, the internal functional component includes a slow-release nutrient matrix. To achieve the goal of adjusting the initial carbon-nitrogen ratio of the weed-microbe system, the required nitrogen mass to be added to this matrix is... The calculation formula is: ； In the formula, The estimated dry weight of weed biomass within a single treatment unit; The average carbon content of weed biomass; The average nitrogen content of weed biomass; The optimal target carbon-nitrogen ratio for microbial decomposition was set.

8. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... The components of the synergistic microcapsules include the following components in parts by weight: Active core, namely the dormant mycelium of dominant indigenous microbial flora: 10-30 parts; The internal functional component comprises a slow-release nutrient matrix of 30-80 parts, N-acylhomoserine lactone of 0.01-0.5 parts, and an organic carbon stabilizer of 20-60 parts. The responsive housing: 5-15 parts; Polysaccharide-degrading enzyme fixed to the outer surface of the responsive housing in the external triggering module: 0.1-1.0 parts.

9. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... The preparation steps of the synergistic microcapsules include: The obtained dominant indigenous microbial community was cultured in liquid fermentation at 28-35℃ for 48-72 hours, and then freeze-dried to prepare the active core. Using a multi-stage fluidized bed, under the condition that the material temperature is controlled at 30-40℃, a suspension containing the internal functional components is coated on the outside of the active core. Continue to coat the outer layer with the solution of the responsive shell while keeping the material temperature controlled at 40-50℃; Finally, glutaraldehyde was used as a crosslinking agent to fix the external trigger module to the outer surface of the responsive shell by covalent coupling at 4-25°C.

10. The method for promoting the decomposition of winter fallow weeds through deep plowing and returning them to the field, and the accumulation of soil organic carbon, as described in claim 1, is characterized in that... In the implementation steps of returning the material to the field for decomposition and organic carbon accumulation, the application of the synergistic microcapsules is carried out at a predetermined dosage. The determination of this initial effective microbial density in the soil is to achieve the predetermined target. The calculation formula is as follows: ； In the formula, The dosage per unit area of ​​the synergistic microcapsule; The initial effective density of microorganisms expected to be achieved in weed-rich areas; The total mass of the target soil region per unit area where the synergistic microcapsules act; The concentration of active microorganisms in the synergistic microcapsule product.

Images