Functional microorganism coupled carbon and nitrogen fixation type organic fertilizer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of environmental engineering and agricultural resource recycling, and particularly relates to a carbon and nitrogen fixation type organic fertilizer as well as a preparation method and application thereof. Carbonate sedimentary bacteria and denitrifying functional bacteria are loaded on a modified silicate mineral raw material, and then mixed with sludge, an organic fertilizer matrix and the like for composting, so that the high-temperature stage (50-60 DEG C) in the composting process is prolonged by 20-30%, the humification rate is increased by 20-30%, and meanwhile, the content of main nutrients such as total nitrogen, total phosphorus, total potassium and the like is increased by 10-15%; after the carbon fixation and nitrogen fixation type organic fertilizer is applied to soil, mineral weathering reaction can be promoted in a soil environment, CO2 in pores is converted into stable carbonate minerals (such as CaCO3 and MgCO3), high cost and complexity of traditional tail gas trapping are avoided, and the CO2 fixation rate is remarkably increased and can reach 75%-85%; the generation of NOx is inhibited, and the synchronous emission reduction of CO2 and nitrogen oxides is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering and agricultural resource recycling, and particularly relates to a functional microorganism-coupled carbon and nitrogen fixation organic fertilizer, a preparation method thereof, and an application thereof. Background Art

[0002] The application of organic fertilizers is an important soil improvement technology in agricultural production, which is widely used to improve soil fertility, increase soil organic matter content, enhance water retention capacity, and promote crop growth. Its sources include organic wastes such as livestock and poultry manure, agricultural straws, green manures, etc., which are converted into organic fertilizers through composting or fermentation and then applied to farmland. However, during the application process of traditional organic fertilizers, significant carbon dioxide (CO2) emissions occur. Especially during the mineralization process of organic fertilizers, the release amount of carbon dioxide is particularly significant. At the same time, the emission problem of nitrogen oxides (NOx, including NO and NO2) generated during the nitrogen transformation process is also prominent, thus affecting the carbon emission reduction target and air quality in the agricultural field.

[0003] During the application process of traditional organic fertilizers, the carbon dioxide emissions mainly come from the "priming effect", that is, after the application of organic fertilizers, the activity of soil microorganisms is enhanced, resulting in an accelerated mineralization rate of the original organic matter in the soil, and then a large amount of CO2 is released. According to research, after the application of organic fertilizers, the mineralization rate of the original organic carbon in the soil can be significantly increased, and about 60% - 70% of the organic carbon will be released into the atmosphere in the form of CO2. This kind of emission not only exacerbates the greenhouse gas emission problem, but also causes resource waste and affects the sustainability of agricultural production.

[0004] During the application process of traditional organic fertilizers, nitrogen transformation is the main way for the generation of NOx, and its oxidation product nitric acid (HNO3) can cause acid rain and soil acidification. Nitrification oxidizes NH4 + to NO3 - , while denitrification reduces NO3 - to gaseous NO and N2. However, in the soil environment with unstable aeration conditions, the release amount of the intermediate product NO during the denitrification process increases significantly. The NO emission makes a direct contribution to the destruction of the ozone layer and the formation of photochemical smog. About 10% - 30% of the nitrogen loss escapes in the form of gaseous nitrogen oxides, which not only reduces the fertilizer utilization rate but also exacerbates the environmental burden. This kind of emission not only exacerbates the greenhouse gas emission problem, but also causes resource waste and affects the sustainability of agricultural production.

[0005] To solve this problem, in recent years, researchers have proposed a method of combining mineral carbon sequestration reactions with organic waste composting. This method involves adding silicate minerals during the composting process and, by leveraging their natural weathering characteristics, capturing the carbon dioxide released during composting and converting it into stable carbonate minerals (such as CaCO3 and MgCO3), thereby reducing greenhouse gas emissions. However, the above method currently still has problems such as low carbon sequestration efficiency, difficulty in significantly reducing agricultural carbon emissions in the short term, insufficient microbial synergy, lack of effective synergy coupling between mineral carbon sequestration and microbial solubilization, lack of systematic CO2 emission management, complex technology, low efficiency, and inability to completely eliminate CO2 release, lack of comprehensive benefits of soil improvement and nutrient enhancement, failure to fully consider the improvement of soil health and the long-term supply of soil nutrients, and neglect of synergistic reduction of nitrogen oxides, with limited inhibitory effect on NOx generation, etc. Summary of the Invention

[0006] In view of the above defects, the purpose of the present invention is to provide a method for preparing a carbon and nitrogen sequestering organic fertilizer, comprising the following steps:

[0007] Prepare a negative carbon capture material: obtained by loading a mixed bacterial solution of carbonate-depositing bacteria and denitrifying functional bacteria after propagation onto a modified silicate mineral material; the modified silicate mineral material is obtained by modifying silicate mineral raw material powder with acetic acid solution;

[0008] Prepare a carbon and nitrogen sequestering organic fertilizer: obtain by mixing the loaded capture material with sludge and auxiliary materials, adding a nitrification inhibitor, and then performing composting.

[0009] Further, the silicate raw material is one or more of serpentine powder, red mud, olivine, and pyroxene.

[0010] Further, the concentration of the acetic acid solution is 0.2 - 0.5 mol·L -1 , the solid-liquid ratio of the silicate mineral raw material powder to the acetic acid solution is 1:1.5 - 1:2, the modification reaction temperature is 40 - 60 °C, and the time is 2 - 4 h.

[0011] Further, the concentration of the propagated mixed bacterial solution is 109 - 10 10 CFU·mL -1 , and the solid-liquid ratio of the modified silicate mineral material to the propagated mixed bacterial solution is 10:1 - 5:1.

[0012] Further, the loading method is vacuum filtration, the relative vacuum degree is -0.07 MPa - -0.1 MPa, and the loading time is 30 min.

[0013] Further, the moisture content of the mixed material is 50 - 60%, and the carbon-nitrogen ratio is 25:1 - 30:1.

[0014] And the carbon and nitrogen fixation organic fertilizer prepared according to the above preparation method.

[0015] The second technical solution of the present application discloses an application method of the above carbon and nitrogen fixation organic fertilizer in agriculture, and the application amount is 2-3 tons / hectare.

[0016] The beneficial effects of the present invention are as follows: 1. In the present application, carbonate-depositing bacteria and denitrifying functional bacteria are loaded on the modified silicate mineral raw material, and then mixed with sludge, organic fertilizer matrix, etc. for composting, so that the high-temperature stage (50-60 °C) in the composting process is extended by 20%-30%. This change effectively improves the degradation efficiency of organic matter and accelerates the stabilization treatment of the compost product (carbon and nitrogen fixation organic fertilizer), shortening the composting cycle by 10%-20%. On the other hand, in the obtained carbon and nitrogen fixation organic fertilizer, the humification rate is increased by 20%-30%, and at the same time, the contents of main nutrients such as total nitrogen, total phosphorus, and total potassium are increased by 10%-15%.

[0017] 2. After the carbon and nitrogen fixation organic fertilizer obtained in the present application is applied to the soil, it can promote the mineral weathering reaction in the soil environment, convert CO2 in the pores into stable carbonate minerals (such as CaCO3 and MgCO3), avoiding the high cost and complexity of traditional tail gas capture, and significantly improving the CO2 fixation rate, which can reach 75%-85%. At the same time, due to the synergistic effect of the introduced denitrifying functional strain and the modified silicate mineral, the denitrifying bacteria directly reduce NO3 - to N2, reducing the accumulation of NO intermediate products; the modified silicate mineral is rich in hydroxyl groups and negatively charged sites, which can adsorb NH3 released in the soil and reduce the substrate (NH4 + ) of the nitrification reaction, thereby inhibiting the generation of NOx and achieving the synchronous reduction of CO2 and nitrogen oxides.

[0018] 3. The carbon and nitrogen fixation organic fertilizer obtained in the present application can also increase the proportion of ammonium nitrogen (NH4 + ) in the soil by 20%-25%, reduce the proportion of nitrate nitrogen (NO3 - ) by 15%-20%, reduce the risk of nitrogen leaching, and at the same time improve the nitrogen utilization rate of crops. The mobility of heavy metals is reduced by 30%-50%, effectively reducing the risk of soil pollution. The generated carbonate improves the physical properties of the compost product, especially enhancing its water holding capacity (20%) and looseness (15%-25%). Detailed implementation manners

[0019] The specific embodiments of the present invention will be described below to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

[0020] The first embodiment of the present application provides a method for preparing a carbon and nitrogen fixation organic fertilizer, including the following steps:

[0021] Prepare a negative carbon capture material: obtained by loading the mixed bacterial solution of carbonate-depositing bacteria and denitrifying functional bacteria after propagation onto a modified silicate mineral material; the modified silicate mineral material is obtained by modifying the silicate mineral raw material powder with acetic acid solution;

[0022] Prepare a carbon and nitrogen fixation organic fertilizer: add a nitrification inhibitor to the mixture of the loaded capture material, sludge, and auxiliary materials to obtain a mixed material, and then obtain it through composting.

[0023] In this embodiment, the silicate raw material is one or more of serpentine, red mud, olivine, and pyroxene. For example, using serpentine alone as the raw material, or using olivine alone as the raw material, or a mixture of serpentine and red mud in a ratio of 3:1, etc., all fall within the general knowledge of those skilled in the art.

[0024] In this embodiment, in order to remove impurities from the silicate raw material and improve its performance, it is preferable to pretreat the raw material. For example, add the raw material powder to deionized water for mixing and then dry it to ensure the stability of subsequent processing; grind the dried raw material to obtain raw material powder with a certain particle size.

[0025] In this embodiment, the purpose of modifying the silicate mineral raw material with acetic acid solution is that acetic acid can remove impurities on the mineral surface through chelation, expose more hydroxyl active sites on the mineral, enhance the surface characteristics of the mineral material, and significantly improve its adsorption capacity for CO2 and NH3. Then, load the carbonate-depositing bacteria and denitrifying functional bacteria on it to construct a microorganism-mineral synergistic system. Among them, the carbonate-depositing bacteria (Sporosarcina pasteurii) can efficiently produce carbonic anhydrase, catalyze the reaction of carbon dioxide and water to form carbonic acid (H2CO3), and generate stable carbonates through reaction with calcium and magnesium ions; the denitrifying bacteria (Pseudomonas stutzeri) can directly reduce NO3 - to N2, reduce the release of NO intermediate products, and combine with the adsorption of NH3 by the modified silicate material (the adsorption amount increases by 40% - 50%) to inhibit the nitrification reaction.

[0026] Preferably, the carbonate-depositing bacteria can be Sporosarcina pasteurii, etc., and the denitrifying functional bacteria can be Pseudomonas stutzeri, etc.

[0027] Furthermore, when applying, the above-mentioned bacteria need to be propagated. Among them, the carbonate-depositing bacteria can be cultured by liquid fermentation process at 30-35 °C until the bacterial liquid concentration reaches 10 9 CFU·mL -1 . The denitrifying functional bacteria are cultured in a modified LB medium (adding 10 g·L-1 potassium nitrate as the nitrogen source, pH 7.2) at 30 °C and 120 r·min-1 shaking condition for 48 hours, and the bacterial liquid concentration reaches 109 CFU·mL-1. The two bacterial liquids are respectively concentrated by centrifugation (8000 r·min-1, 10 minutes) to obtain high-density bacterial agents (concentration 1011 CFU·mL-1).

[0028] In this embodiment, the loading adopts vacuum filtration technology. The modified mineral material is soaked in the high-density bacterial liquid, and the bacterial liquid is driven to penetrate into the material interior by a negative pressure of -0.07 to -0.1 MPa to ensure the uniform distribution of microorganisms on the material surface and in the pores.

[0029] Another embodiment of the present application discloses the application of the carbon-fixing and nitrogen-fixing organic fertilizer prepared by the above preparation method in agricultural production, and its application rate is preferably 2-3 tons / ha.

[0030] When applying, according to the soil conditions and crop types, the basal application or furrow application method is adopted, and 2-3 tons of carbon-fixing organic fertilizer are applied per hectare to ensure the uniform distribution of minerals and microorganisms in the plough layer (0-20 cm). After application, the moisture and CO2 in the soil activate the weathering reaction of the minerals to form stable carbonates, promoting the fixation of CO2. At the same time, the following synergistic mechanism is used to achieve NOx emission reduction:

[0031] (1) NH3 adsorption inhibits nitrification: The adsorption amount of NH3 on the surface hydroxyl sites of the modified serpentine increases by 40%-50%, reducing the nitrification substrate (NH4 + ), thereby inhibiting NO generation.

[0032] (2) Denitrification enhancement: Denitrifying bacteria (such as Pseudomonas stutzeri) directly reduce NO3 - to N2, reducing the release of the intermediate product NO. Field tests show that the NO emissions are reduced by 25%-35%.

[0033] The carbon dioxide released during composting and application is captured by the negative carbon capture material and mineralized into carbonates through the following reaction:

[0034] CaSiO3 + 2CO2 + 3H2O → Ca 2+ + 2HCO 3- + H4SiO4;

[0035] CaCO3 + CO2 + H2O → Ca 2+ + 2HCO 3- ;

[0036] Ca 2+ + 2HCO 3- → CaCO3↓ + CO2 + H2O;

[0037] Mg 2+ + 2HCO 3- → MgCO3↓ + CO2 + H2O。

[0038] The carbon sequestration efficiency of the mineralization reaction can reach 30% - 50%. The generated carbonates are stably stored in the compost product, significantly increasing the inorganic carbon content and long-term stability of the compost product. Microorganisms secrete organic acids and carbonic anhydrase, further accelerating mineral dissolution and carbonate precipitation, while improving the soil's acid-base balance, enhancing the pH value, buffering capacity, and nutrient release. After applying the carbon sequestration organic fertilizer for 1 year, the soil organic matter content increases by 15% - 25%, the main nutrients (total nitrogen, total phosphorus, total potassium) increase by 10% - 15%, the soil aggregate structure is improved, the porosity increases by 20% - 30%, and the water retention capacity increases by 15% - 20%. In addition, the proportion of ammonium nitrogen (NH4 + ) in the soil increases by 20% - 25%, the leaching loss of nitrate nitrogen (NO3 - ) decreases by 15% - 20%, the mobility of heavy metals decreases by 30% - 50%, and the nitrogen use efficiency of crops increases by 10% - 15%. This method not only helps with carbon sequestration but also significantly improves soil health and agricultural sustainability by inhibiting NOx generation and optimizing the nitrogen cycle.

[0039] The technical effects of this application will be described in detail through specific examples below.

[0040] Example 1 Preparation of carbon sequestration and nitrogen fixation organic fertilizer

[0041] S1. Preparation of negative carbon capture material

[0042] (1) Preparation of modified silicate mineral material: Mix serpentine powder and red mud in a mass ratio of 3:1, add 10% of its mass fraction of deionized water to mix and moisten, vacuum dry at 105°C until the water content is lower than 10%, and then place it in a high-energy ball mill for grinding (set the ball-to-material ratio to 10:1, the ball mill rotation speed is 500r·min -1 , for 3h), and pass the ball-milled raw material through a 50μm sieve to obtain the pretreated silicate mineral material;

[0043] The pretreated silicate mineral material was mixed with acetic acid solution at a solid-liquid ratio of 1:5, stirred and modified at 50 °C for 3 h, filtered through a vacuum filtration device, washed with deionized water until neutral, and then dried to constant weight. -1 It was obtained after being washed with deionized water until neutral and then dried to constant weight after being filtered through a vacuum filtration device.

[0044] (2) Microbial loading

[0045] The carbonate-depositing bacterium (Sporosarcina pasteurii) was cultured by liquid fermentation process at 30 - 35 °C until the bacterial liquid concentration reached 10 9 CFU·mL-1. The denitrifying functional bacterium (Pseudomonas stutzeri) was cultured in a modified LB medium (added with 10 g·L -1 potassium nitrate as the nitrogen source, pH 7.2) at 30 °C and 120 r·min -1 under shaking conditions for 48 hours, and the bacterial liquid concentration reached 10 9 CFU·mL -1 . The two kinds of bacterial liquids were respectively concentrated by centrifugation (8000 r·min -1 , 10 minutes) to obtain high-density bacterial agents (concentration 1011 CFU·mL -1 ).

[0046] The modified silicate mineral material was immersed in the expanded mixed bacterial liquid, and the microorganisms were loaded on the material surface by vacuum filtration. The vacuum degree was set to -0.07 - -0.1 MPa, the loading time was 30 min, and after the loading was completed, the material was taken out and slowly dried at 30 °C to obtain the negative carbon capture material.

[0047] S2. Preparation of carbon and nitrogen fixation organic fertilizer: The loaded capture material was mixed with sludge and auxiliary materials, and then 0.1% - 0.3% nitrification inhibitor dicyandiamide was added. The carbon-nitrogen ratio (C / N) was maintained at 30:1, the ventilation rate of the compost pile was regulated to 0.2 - 0.5 L·min-1·kg-1, and the micro-aerobic environment (O2 concentration 5% - 10%) was maintained to obtain the compost by the windrow composting process, where the compost pile was 1.2 m high.

[0048] Example 2 Preparation of carbon and nitrogen fixation organic fertilizer

[0049] S1. Preparation of negative carbon capture material

[0050] (1) Preparation of modified silicate mineral material:

[0051] Mix peridot powder (Mg2SiO4 content ≥ 85%) with red mud at a mass ratio of 2:1, add deionized water with a mass fraction of 8% for wetting, and vacuum dry at 110 °C until the water content is < 8%. Activate using a planetary ball mill (ball-to-material ratio 12:1, rotation speed 550 r·min-1, for 4 h), and obtain activated mineral powder with D50 = 20 μm by sieving;

[0052] Add the activated powder to a 0.1 - 0.3 mol·L-1 acetic acid solution at a solid-liquid ratio of 1:6, and modify it by ultrasonic assistance (40 kHz) at 45 °C for 2.5 h. After vacuum filtration and washing with a pH = 6.5 buffer solution, vacuum dry at 60 °C until constant weight.

[0053] (2) Microbial composite loading

[0054] Select silicate-decomposing bacterium Bacillus mucilaginosus (CGMCC 1.232) and nitrogen-fixing bacterium Azotobacter chroococcum (ACCC 11011) to construct a functional microbial community: B. mucilaginosus is cultured in a modified sucrose medium (sucrose 10 g / L, MgSO4·7H2O 0.5 g / L, K2HPO4 0.2 g / L) at 35 °C and 180 rpm until OD600 = 1.8; A. chroococcum is cultured in a nitrogen-free Ashby medium (mannitol 15 g / L, CaCO3 0.1 g / L) at 30 °C statically for 72 h.

[0055] Prepare a composite bacterium agent (10 10 CFU·mL -1 ) by gradient centrifugation (10000 r / min, 15 min). After mixing at a volume ratio of 3:2, load it onto the modified mineral by vacuum impregnation (-0.08 MPa, 25 min), and obtain the composite material by low-oxygen drying at 35 °C (O2 concentration 8%).

[0056] S2. Preparation of carbon and nitrogen fixation organic fertilizer:

[0057] Mix the loaded material with municipal sludge and straw powder (water content 60%) at a mass ratio of 1:5:2, add 0.05% nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), and adjust the initial C / N = 28:1. Use a forced ventilation reactor to control the ventilation volume at 0.3 L·min -1 ·kg -1 , maintain the heap temperature at 55 - 65 °C for 5 days. Later, transfer to the composting stage (40 - 45 °C, O2 concentration 3 - 5%) and maintain for 10 days. During this period, add 2% humic acid to promote mineral-organic matter complexation.

[0058] Example 3 Preparation of carbon and nitrogen fixation organic fertilizer

[0059] S1. Prepare negative carbon capture materials

[0060] (1) Prepare modified composite silicate mineral materials

[0061] Mix pyroxene powder (CaMgSi2O6 content ≥ 75%), serpentine powder (Mg3Si2O5(OH)4 content ≥ 80%) and montmorillonite (supplementary layered silicate) according to a mass ratio of 4:3:1, add 12% deionized water to wet, and vacuum dry at 105°C until the water content < 9%. Gradient activation is carried out using a planetary ball mill:

[0062] First stage: The ball-to-material ratio is 8:1, and the rotation speed is 400 r·min -1 , lasting for 2 h (pre-crushing the serpentine flaky structure)

[0063] Second stage: The ball-to-material ratio is 15:1, and the rotation speed is 600 r·min -1 , lasting for 3 h (targeted crushing of the pyroxene dense lattice)

[0064] Sieve to obtain a composite mineral powder with D90 < 30 μm. Add the activated powder to a 0.4 mol·L -1 citric acid-acetic acid mixed acid solution (volume ratio 2:1) according to a solid-liquid ratio of 1:4, and perform ultrasonic-microwave synergistic treatment (40 kHz + 300 W) at 50°C for 1.5 h. After centrifugal separation (5000 r / min, 10 min) and washing with 0.1 mol·L-1 EDTA solution to remove the surface passivation layer, dry in a fluidized bed at 45°C to constant weight.

[0065] (2) Microbial directional loading

[0066] Select silicate-decomposing bacteria Bacillus subtilis (CICC 10283), methanotrophic bacteria Methylococcus capsulatus (ATCC 33009), and acid-tolerant nitrogen-fixing bacteria Acidithiobacillus ferrooxidans (DSM 14882) to construct a functional flora:

[0067] B. subtilis uses Fe 3+ enriched medium (containing 0.5 g / L FePO4), and culture at 37°C and 200 rpm until OD600 = 2.0;

[0068] M. capsulatus is cultured at 30°C for 5 days in a methane / air (1:4) atmosphere;

[0069] A. ferrooxidans uses 9K medium (pH = 3.0) and is statically cultured at 28°C for 7 days;

[0070] The composite bacterial suspension (total bacterial concentration 10 12 CFU·mL -1 ) was obtained by membrane filtration concentration (0.22 μm ceramic membrane), and after mixing in a volume ratio of 4:3:3, the pulse vacuum loading technology (-0.09 MPa pulse × 20 times, 30 s each time) was adopted, and the loading rate was increased to 92%, and dried under the protection of inert gas at 40 °C.

[0071] S2. Preparation of carbon-fixing and nitrogen-fixing organic fertilizer

[0072] The loaded material was mixed with livestock and poultry manure and rice husk charcoal in a mass ratio of 1:6:1.5, 0.2% nitrification inhibitor thiourea was added, and the initial C / N was adjusted to 25:1. Two-stage fermentation was adopted:

[0073] High-temperature stage: Maintain at 65 °C for 7 days, and mechanically turn the pile every 12 h (to promote the release of Ca in pyroxene 2+ release and CO2 mineralization)

[0074] Medium-temperature ripening: Oxygen-controlled fermentation at 45 °C (O2 concentration 2-5%) for 15 days, and 1.5% trehalose was added to maintain the microbial activity.

[0075] Preparation of carbon-fixing and nitrogen-fixing organic fertilizer in Comparative Example 1

[0076] The preparation method was the same as that in Example 1, except that in Comparative Example 1, no silicate mineral material and microorganism were added.

[0077] Test Example 1 Performance test of carbon-fixing and nitrogen-fixing organic fertilizer

[0078] The humification rate, total nitrogen, total phosphorus, and total potassium of the organic fertilizers prepared in Example 1 and Comparative Example 1 were tested. Among them, the test method for the humification rate was:

[0079] 1. Sample pretreatment: Take the air-dried sample (soil or compost) and pass it through a 0.25 mm sieve. The total organic carbon (TOC) content was determined by the potassium dichromate-sulfuric acid method.

[0080] 2. Fractional extraction of humus:

[0081] (1) Extraction of humic acid (HA): The sample was mixed with 0.1 mol / L NaOH solution (solid-liquid ratio 1:10), shaken for 24 hours, and the supernatant was separated by centrifugation. The pH of the supernatant was adjusted to 1.0 (with 6 mol / L HCl), and left standing for 24 hours, and the precipitate (HA) was collected by centrifugation.

[0082] (2) Extraction of fulvic acid (FA): The remaining liquid after centrifugation above was filtered through a 0.45 μm filter membrane, and the filtrate was the FA solution.

[0083] (3) Non-humic substances (NH): The remaining residue was washed with deionized water until neutral, and its organic carbon content was measured after drying.

[0084] 4. Calculate the humification rate

[0085] The test methods for total nitrogen, total phosphorus, and total potassium are as follows: Kjeldahl method (N), molybdenum-antimony anti-colorimetric method (P), and flame photometry method (K). The test results are shown in Table 1.

[0086] Table 1 Performance test results

[0087]

[0088] As can be seen from Table 1, compared with traditional organic fertilizers, the organic fertilizers produced by this technology can significantly increase the humification rate, and the contents of total nitrogen, total potassium, and total phosphorus are all improved, with an average increase of 15% respectively. While carbon sequestration is achieved, the overall health and fertility of the soil are improved in all aspects, and the soil structure is significantly improved.

[0089] Experimental example 2 Application experiment

[0090] The organic fertilizers prepared in Example 1 and Comparative Example 1 were applied to the soil at a dosage of 2.5 tons / ha. After use (specific time), the reduction amounts of CO2 and nitrogen oxides (NOx), the ammonium nitrogen (NH4 + ), nitrate nitrogen (NO3 - ), mobility of heavy metals, carbonates, water holding capacity, and looseness in the soil were tested. The specific test methods are as follows: The CO2 reduction amount was determined by the sodium hydroxide collection method; the NOx reduction amount was determined by a portable gas analyzer; the ammonium nitrogen (NH4 + ), nitrate nitrogen (NO3 - ) in the soil were determined by the Kjeldahl method; the mobility of heavy metals was determined by continuous extraction and atomic absorption spectrometry; the carbonate content was determined by acid-base titration; the water holding capacity was determined by the soil water characteristic curve method; the looseness was evaluated by the soil permeability test method. The experimental results are shown in Table 2.

[0091] Table 2 Application experiment results

[0092]

[0093] Result analysis: In-situ capture and mineralization fixation of CO2 during the farmland application process were achieved, avoiding the high cost and complexity of traditional tail gas capture. The CO2 fixation rate was significantly improved, reaching 50% - 70%; at the same time, the NO emission was reduced by 25% - 35%, and the NO2 emission was reduced by 15% - 20%. The proportion of ammonium nitrogen (NH4 + ) in the soil increased significantly, and the proportion of nitrate nitrogen (NO3 -)The proportion is significantly reduced, reducing the risk of nitrogen leaching while increasing the nitrogen utilization rate of crops; the mobility of heavy metals is reduced by 30% - 50%, effectively reducing the risk of soil pollution; the generated carbonate improves the physical properties of the compost product, especially enhancing its water holding capacity and looseness. These improvements provide better soil improvement effects and comprehensive fertility for the compost product.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a functional microbial coupled carbon and nitrogen fixation organic fertilizer, characterized in that: The steps include: Preparation of negative carbon capture material: the mixed bacterial liquid of expanded carbonate deposition bacteria and denitrification functional bacteria is loaded on a modified silicate mineral material; the modified silicate mineral material is obtained by modifying silicate mineral raw material powder with acetic acid solution; Preparation of functional microbial coupled carbon and nitrogen fixation organic fertilizer: the loaded capture material is mixed with sludge and auxiliary materials, and then a nitrification inhibitor is added to obtain a mixed material, and the mixed material is obtained by composting.

2. The preparation method according to claim 1, characterized in that: The silicate raw material is one or more of serpentine, red mud, olivine and pyroxene.

3. The preparation method according to claim 1, characterized in that: The concentration of the acetic acid solution is 0.2-0.5 mol·L -1 The solid-liquid ratio of silicate mineral raw material powder to acetic acid solution is 1:1.5~1:2, the modification reaction temperature is 40~60℃, and the time is 2~4h.

4. The preparation method according to claim 1, characterized in that: The concentration of the mixed bacterial solution for propagation is 109 to 10 10 CFU·mL -1 The solid-liquid ratio of the modified silicate mineral material to the mixed bacterial liquid after expansion is 10:1 to 5:

1.

5. The preparation method according to claim 1, characterized in that: The loading method is vacuum filtration, the relative vacuum degree is -0.07MPa to -0.1MPa, and the loading time is 30min.

6. The preparation method according to claim 1, characterized in that: The water content of the mixed material is 50-60%, and the carbon-nitrogen ratio is 25:1-30:

1.

7. A carbon-fixing and nitrogen-fixing organic fertilizer obtained according to the preparation method of claim 1.

8. The use of the carbon-fixing and nitrogen-fixing organic fertilizer in agricultural fertilization according to claim 7, characterized in that: The application rate is 2-3 tons / hectare.

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