A soil improvement material, a method for preparing the same, and an application thereof

Abstract

The application relates to the technical field of soil improvement, and discloses a soil improvement material and a preparation method and application thereof. According to mass percentage, the soil improvement material comprises the following preparation raw materials: 40-70% of an expanded modified layered silicate mineral, 20-55% of organic fertilizer and 1-10% of a polyhydric sugar alcohol. The application utilizes the expanded modified layered silicate mineral to provide active space and sites, utilizes the polyhydric sugar alcohol molecules to build a dense and stable three-dimensional hydrogen bond network between the surface and interlayer of the expanded modified layered silicate mineral and the active functional groups of the organic fertilizer by virtue of the polyhydric property of the molecules. The chemical bonding structure fundamentally overcomes the problems of easy layering and rapid decomposition of organic matter in traditional physical mixing, realizes physical wrapping and chemical locking of organic carbon, significantly reduces the microbial availability of the organic carbon, and inhibits the generation of greenhouse gases such as methane and nitrous oxide from the source. The preparation method of the soil improvement material is simple in steps, the raw materials are easy to obtain, and batch production can be easily realized.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, and in particular to a soil improvement material, its preparation method, and its application. Background Technology

[0002] Soil is a significant source of methane (CH4) and nitrous oxide (N2O) emissions into the atmosphere, both of which have a significant impact on global climate change. Currently, in the field of agricultural soil improvement, materials such as biochar and zeolite are commonly used to reduce gas emissions and improve soil fertility. However, their effectiveness has the following obvious limitations: While biochar possesses good physical adsorption properties, its surface chemically active sites are insufficient, making it difficult to chemically anchor easily decomposable organic carbon in the soil, resulting in limited long-term carbon fixation effects; ordinary zeolite materials mainly rely on ion exchange, making a relatively small direct contribution to carbon fixation, and their effect on suppressing methane emissions is not significant.

[0003] Furthermore, while applying organic fertilizer alone can replenish soil organic matter, it significantly increases biodegradable carbon sources, which in turn stimulates microbial activity and exacerbates the emission of CH4 and N2O. Conversely, using mineral materials alone lacks an organic binding mechanism, making it difficult to form stable soil aggregates and thus limiting its effectiveness in improving soil physical properties. Simply mixing minerals and organic fertilizers physically not only fails to create a stable composite system but may also release more greenhouse gases in the short term due to the rapid decomposition of organic matter.

[0004] Therefore, developing a novel composite material with a stable chemical bonding network in its microstructure to inhibit CH4 generation in soil at the source (carbon fixation), reduce N2O emissions, and prolong nitrogen availability (nitrogen retention) is of great significance for promoting green and low-carbon agricultural development, improving sustainable soil productivity, and reducing greenhouse gas emissions. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a soil amendment material.

[0006] The second objective of this invention is to provide a method for preparing this soil amendment material.

[0007] The third objective of this invention is to provide the application of this soil amendment material.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a soil amendment material comprising, by weight percentage, the following raw materials: 40%-70% expanded modified layered silicate minerals, 20%-55% organic fertilizer, and 1%-10% polysaccharide alcohols.

[0009] In some embodiments of the present invention, the soil amendment material comprises the following raw materials by weight percentage: 45%-70% expanded modified layered silicate minerals, 25%-50% organic fertilizer, and 1%-6% polysaccharide alcohols.

[0010] In some embodiments of the present invention, the particle size of the soil amendment material is less than 5 mm.

[0011] In some embodiments of the present invention, the expanded modified layered silicate mineral has an interlayer structure with an interlayer spacing greater than 1.4 nm.

[0012] In some embodiments of the present invention, the expanded modified layered silicate mineral comprises that obtained by instantaneous heat treatment of expanded layered silicate mineral.

[0013] In some embodiments of the present invention, the expandable layered silicate mineral has an expandable interlayer structure with an interlayer spacing greater than 0 and less than or equal to 1.2 nm.

[0014] In some embodiments of the present invention, the particle size of the expandable layered silicate mineral is 1-5 mm.

[0015] In some preferred embodiments of the present invention, the particle size of the expandable layered silicate mineral is 1-3 mm.

[0016] In some embodiments of the present invention, the expansive layered silicate mineral includes at least one of vermiculite, perlite, bentonite, montmorillonite, and rettoite.

[0017] In some embodiments of the present invention, the instantaneous heat treatment temperature is 800-950°C and the time is 10-60 seconds.

[0018] In some preferred embodiments of the present invention, the instantaneous heat treatment temperature is 850-950°C and the time is 20-30 seconds.

[0019] In some embodiments of the present invention, the specific surface area of ​​the expandable layered silicate mineral is increased by 5-10 times after instantaneous heat treatment.

[0020] In some embodiments of the present invention, the volume of the expandable layered silicate mineral increases by 8-10 times after instantaneous heat treatment.

[0021] In some embodiments of the present invention, the organic fertilizer includes at least one of decomposed livestock and poultry manure and fermented plant residues.

[0022] In some embodiments of the present invention, the particle size of the organic fertilizer is 1-5 mm.

[0023] In some preferred embodiments of the present invention, the particle size of the organic fertilizer is less than 2 mm.

[0024] In some embodiments of the present invention, the organic fertilizer has a moisture content of less than 15%.

[0025] In some embodiments of the present invention, the decomposed livestock and poultry manure includes at least one of decomposed chicken manure, duck manure, goose manure, pigeon manure, cow manure, pig manure, sheep manure, and horse manure.

[0026] In some preferred embodiments of the present invention, the decomposed livestock and poultry manure is selected from at least one of decomposed chicken manure and decomposed cow manure.

[0027] Specifically, chicken manure is high in nitrogen, phosphorus, potassium, and organic matter, and has a rapid fertilizing effect after decomposition; cow manure is high in organic matter, rich in fiber, and has a dense texture, which has a good effect on improving the physical structure of the soil.

[0028] In some embodiments of the present invention, the fermented plant residue includes at least one of fermented crop straw and fruit and vegetable processing by-products.

[0029] In some preferred embodiments of the present invention, the crop straw includes at least one of gramineous crop straw, leguminous crop straw, and economic crop residues.

[0030] In some preferred embodiments of the present invention, the fruit and vegetable processing by-products include at least one of fruit pomace and vegetable residues.

[0031] In some embodiments of the present invention, the polyols include at least one of galactitol, mannitol, sorbitol, xylitol, and erythritol.

[0032] In some preferred embodiments of the present invention, the polyol is galactitol.

[0033] Specifically, the straight-chain structure and high density of hydroxyl groups of galactitol are more conducive to the formation of a dense hydrogen bond network.

[0034] The second aspect of the present invention provides a method for preparing the soil amendment material described in the first aspect of the present invention, comprising the following steps: The expanded modified layered silicate minerals were mixed with organic fertilizer, and an aqueous solution of polysaccharide alcohol was applied to the surface of the resulting mixture for maturation to obtain the soil amendment material.

[0035] In some embodiments of the present invention, the time for mixing the expanded modified layered silicate minerals with the organic fertilizer is 10-15 minutes.

[0036] In some embodiments of the present invention, the method of applying the aqueous solution of polysaccharide alcohol includes uniform spraying using a high-pressure spraying device.

[0037] In some embodiments of the present invention, the process of applying the aqueous solution of polysaccharide alcohol is accompanied by stirring at a speed of 50-70 r / min for a time of 20-40 min.

[0038] In some embodiments of the present invention, the curing temperature is ≤60°C and the time is 10-24h.

[0039] In some preferred embodiments of the present invention, the curing temperature is 50-60°C and the time is 10-15 hours.

[0040] In some embodiments of the present invention, after the maturation is completed, the process further includes crushing and sieving to obtain the soil amendment material.

[0041] The third aspect of the invention provides for any application of the soil amendment material described in the first aspect of the invention in the following aspects: a. Reduce greenhouse gas emissions from soil; b. Improve soil nitrogen retention capacity; c. Improve soil physical structure; d. Increase soil organic matter content.

[0042] In some embodiments of the present invention, the greenhouse gas includes at least one of methane and nitrous oxide.

[0043] In some embodiments of the present invention, the improvement of soil physical structure includes improving soil porosity, aeration and water retention.

[0044] In some embodiments of the present invention, the soil includes at least one of flooded soil and arid soil.

[0045] In some embodiments of the present invention, the application is to reduce methane and nitrous oxide emissions from flooded soils while simultaneously improving the soil's ammonium nitrogen retention capacity.

[0046] In some embodiments of the present invention, the application is to reduce nitrous oxide and carbon dioxide emissions from arid soils while simultaneously improving the soil's ammonium nitrogen retention capacity.

[0047] In some embodiments of the present invention, the amount of the soil amendment material used is 1-5g / 100g soil (dry weight).

[0048] In some preferred embodiments of the present invention, the amount of the soil amendment material is 1-3g / 100g soil (dry weight).

[0049] The basic principles of this invention are explained as follows: 1) This invention uses expanded modified layered silicate minerals as structural frameworks and reactive carriers. The expanded modified layered silicate minerals are obtained by high-temperature instantaneous heat treatment using expanded layered silicate minerals as raw materials. Expandable layered silicate minerals have expandable interlayer domains containing interlayer water or bound water, providing potential space for constructing composite networks. The silanol (Si-OH) and aluminumol (Al-OH) hydroxyl groups on their surface are key chemically active sites. During the high-temperature instantaneous heat treatment, the interlayer water vaporizes instantaneously, generating high pressure, which acts on the mineral layers, causing the mineral volume to expand, the interlayer spacing to increase, and the specific surface area to increase, providing a huge physical space and attachment interface for loading organic fertilizer. At the same time, the high temperature also causes the mineral surface structure to reorganize, exposing a large number of fresh Si-OH / Al-OH active sites. These sites are charged and highly chemically active, and can serve as anchoring points for forming hydrogen bonds with polysaccharides. 2) Using organic fertilizer as an organic carbon source and nutrient reservoir, organic fertilizer that has been decomposed or fermented stabilizes the organic matter and generates substances rich in humic acid, fulvic acid and other substances containing a large number of active functional groups. These functional groups can chemically bond with polysaccharides, avoiding the negative effects of rapid decomposition of fresh materials. 3) Polysaccharides are used as bridging agents to connect expanded modified layered silicate minerals and organic fertilizers. Their molecular structure contains a high density of hydroxyl groups (-OH). These -OH can form hydrogen bonds with Si-OH / Al-OH on the surface of minerals, and also with functional groups such as carboxyl groups (-COOH) and amino groups (-NH2) in organic fertilizers, thus possessing the chemical ability to construct a three-dimensional network.

[0050] 4) After the expanded modified layered silicate minerals, organic fertilizer and polyols undergo intermolecular contact and initial bonding, they are dried at low temperature. Under the drive of gentle heat, the water gradually evaporates, and the contact interface between the polyols, expanded modified layered silicate minerals and organic fertilizer becomes tighter. Multiple hydroxyl groups of polyol molecules undergo dehydration condensation and strong hydrogen bond association with the functional groups of expanded modified layered silicate minerals and organic fertilizer, forming a three-dimensional spatial network structure that wraps and anchors the organic fertilizer particles between the layers and on the surface of expanded modified layered silicate minerals. This network firmly binds the components through hydrogen bonds rather than physical forces.

[0051] Compared with the prior art, the beneficial effects of the present invention are: 1) The soil amendment material provided by this invention utilizes expanded modified layered silicate minerals to provide active space and sites, and utilizes the polyhydroxyl properties of polyol molecules as molecular bridges to construct a dense and stable three-dimensional hydrogen bond network on the surface of expanded modified layered silicate minerals, between layers and between the active functional groups of organic fertilizer. This chemical bonding structure fundamentally overcomes the problems of easy stratification and excessively rapid decomposition of organic matter in traditional physical mixing, and achieves physical encapsulation and chemical locking of organic carbon, significantly reducing its microbial availability and inhibiting the generation of greenhouse gases such as methane and nitrous oxide from the source. 2) The method for preparing soil amendment materials provided by this invention has simple steps, readily available raw materials, and is easy to mass-produce; 3) When the soil amendment material provided by this invention is applied to flooded soil, it can effectively inhibit the activity of methanogenic bacteria, reducing methane emissions by more than 22% compared with the blank control. At the same time, through mineral adsorption and slow release mechanisms, it can maintain ammonium nitrogen in the rhizosphere for a long time, keeping the soil ammonium nitrogen content at a high level during the mid-crop growth period, and inhibiting the nitrification-denitrification process, reducing nitrous oxide emissions by 67.8%. In addition, the material has a granular structure, which can improve the soil aggregate structure, maintain a long-term nutrient supply, and achieve synergistic effect of carbon sequestration and nitrogen retention, providing an efficient and stable soil amendment solution for green and low-carbon agricultural production. Attached Figure Description

[0052] Figure 1 Here is a SEM image of the expanded modified vermiculite in Example 1; Figure 2 Here is an SEM image of the decomposed cow dung from Example 1; Figure 3 SEM image of the soil amendment material in Example 1; Figure 4 FTIR images of expanded modified vermiculite (a), decomposed cow manure (b), galactitol (c), and soil amendment (d) in Example 1; Figure 5 A comparison of CH4 and N2O emission fluxes between treatment group 1 and treatment group 4 in a pot experiment; Figure 6 Soil-extracted NH4 from treatment groups 1 and 4 in the pot experiment + Changes in content; Figure 7 The relative abundance of *Methanobacterium* (a) and *Pseudomonas* (b) in soil samples from treatment groups 1 and 4 during the pot experiment. Detailed Implementation

[0053] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0054] Example 1 This embodiment prepares a soil amendment material, and the steps are as follows: S1. Select vermiculite with a particle size of 1-3mm, place it in a high-temperature heating furnace, and perform instantaneous high-temperature heat treatment at 900℃ for 30s to obtain expanded modified vermiculite; S2. Weigh 50g of galactitol and add it to 500mL of deionized water. Stir at 300r / min in a 40℃ water bath until completely dissolved to obtain a clear and transparent aqueous solution of galactitol. S3. Place 500g of expanded modified vermiculite and 450g of well-rotted cow manure (particle size less than 2mm, moisture content less than 15%) in a horizontal ribbon mixer and premix for 10min to form a mixture. Then, under stirring (speed 60r / min), use a high-pressure spray device to evenly spray galactitol aqueous solution onto the surface of the mixture and continue stirring for 30min to ensure that the solution fully penetrates into the interlayer of expanded modified vermiculite and the micropores of organic fertilizer to obtain the mixture. S4. Take out the mixture, spread it evenly on a tray, and place it in a 60℃ forced-air drying oven for low-temperature maturation and drying for 12 hours. After drying, the material is crushed by a pulverizer and passed through a 40-mesh sieve to obtain soil amendment material.

[0055] Example 2 This embodiment prepares a soil amendment material, and the steps are as follows: S1. Select perlite with a particle size of 1-3mm, place it in a high-temperature heating furnace, and perform instantaneous high-temperature heat treatment at 950℃ for 20s to obtain expanded modified perlite. S2. Weigh 50g of galactitol and add it to 500mL of deionized water. Stir at 300r / min in a 40℃ water bath until completely dissolved to obtain a clear and transparent aqueous solution of galactitol. S3. Place 500g of expanded modified perlite and 450g of well-rotted cow manure (particle size less than 2mm, moisture content less than 15%) in a horizontal ribbon mixer and premix for 10min to form a mixture. Then, under stirring (speed 60r / min), use a high-pressure spray device to evenly spray galactitol aqueous solution onto the surface of the mixture and continue stirring for 30min to ensure that the solution fully penetrates into the interlayer of expanded modified perlite and the micropores of organic fertilizer to obtain the mixture. S4. Take out the mixture, spread it evenly on a tray, and place it in a 60℃ forced-air drying oven for low-temperature maturation and drying for 12 hours. After drying, the material is crushed by a pulverizer and passed through a 40-mesh sieve to obtain soil amendment material.

[0056] Example 3 This embodiment prepares a soil amendment material, and the steps are as follows: S1. Select vermiculite with a particle size of 1-3mm, place it in a high-temperature heating furnace, and perform instantaneous high-temperature heat treatment at 900℃ for 30s to obtain expanded modified vermiculite; S2. Weigh 50g of mannitol and add it to 500mL of deionized water. Stir at 300r / min in a 40℃ water bath until completely dissolved to obtain a clear and transparent mannitol aqueous solution. S3. Place 500g of expanded modified vermiculite and 450g of well-rotted cow manure (particle size less than 2mm, moisture content less than 15%) in a horizontal ribbon mixer and premix for 10min to form a mixture. Then, under stirring (speed 60r / min), use a high-pressure spray device to evenly spray mannitol aqueous solution onto the surface of the mixture and continue stirring for 30min to ensure that the solution fully penetrates into the interlayer of expanded modified vermiculite and the micropores of organic fertilizer to obtain the mixture. S4. Take out the mixture, spread it evenly on a tray, and place it in a 60℃ forced-air drying oven for low-temperature maturation and drying for 12 hours. After drying, the material is crushed by a pulverizer and passed through a 40-mesh sieve to obtain soil amendment material.

[0057] Example 4 This embodiment prepares a soil amendment material, and the steps are as follows: S1. Select vermiculite with a particle size of 1-3mm, place it in a high-temperature heating furnace, and perform instantaneous high-temperature heat treatment at 900℃ for 30s to obtain expanded modified vermiculite; S2. Weigh 10g of galactitol and add it to an appropriate amount of deionized water (to maintain the minimum liquid volume required for spraying). Stir at 300r / min in a 40℃ water bath until completely dissolved to obtain a clear and transparent aqueous solution of galactitol. S3. Place 700g of expanded modified vermiculite and 290g of well-rotted cow manure (particle size less than 2mm, moisture content less than 15%) in a horizontal ribbon mixer and premix for 10min to form a mixture. Then, under stirring (speed 60r / min), use a high-pressure spray device to evenly spray galactitol aqueous solution onto the surface of the mixture and continue stirring for 30min to ensure that the solution fully penetrates into the interlayer of expanded modified vermiculite and the micropores of organic fertilizer to obtain the mixture. S4. Take out the mixture, spread it evenly on a tray, and place it in a 60℃ forced-air drying oven for low-temperature maturation and drying for 12 hours. After drying, the material is crushed by a pulverizer and passed through a 40-mesh sieve to obtain soil amendment material.

[0058] Comparative Example 1 This comparative example prepares a soil amendment material, and the steps are as follows: S1. Select vermiculite with a particle size of 1-3mm, place it in a high-temperature heating furnace, and perform instantaneous high-temperature heat treatment at 900℃ for 30s to obtain expanded modified vermiculite; S2. Place 500g of expanded modified vermiculite and 450g of decomposed cow manure (particle size less than 2mm, moisture content less than 15%) in a horizontal ribbon mixer and mix for 40 minutes to obtain soil amendment material.

[0059] Material characterization The expanded modified layered silicate minerals, organic fertilizers, and soil amendments in the examples were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy: Figure 1 The image shows the SEM image of the expanded modified vermiculite in Example 1. Table 1 compares the physicochemical properties of the raw vermiculite and the expanded modified vermiculite in Example 1. Figure 1 As shown in Table 1, expanded modified vermiculite exhibits a typical layered silicate structure with a relatively smooth and flat surface and clearly visible interlayer domains. Compared to raw vermiculite, the interlayer spacing of expanded modified vermiculite increases to over 1.4 nm, making it easier for ions / molecules to enter. Its volume expands 8-10 times, and its specific surface area increases to 28.6 m². 2 / g (an increase of approximately 8.2 times), providing ample space for the loading of organic fertilizer.

[0060] Table 1. Comparison of physicochemical properties between raw vermiculite and expanded modified vermiculite of Example 1

[0061] Figure 2 This is a SEM image of the well-rotted cow dung from Example 1. Figure 2 It can be seen that well-rotted cow dung presents a rough, irregular blocky or fibrous aggregate structure with a loose structure.

[0062] Figure 3 The image shows a SEM image of the soil amendment material in Example 1. Figure 3 It can be seen that the interlayer and surface of the expanded modified vermiculite are covered and filled with a dense organic material. The decomposed cow manure is no longer an independent loose body, but is tightly attached to and anchored to the surface of the expanded modified vermiculite through galactitol bridging agent, forming a blurred inorganic-organic interface. This indicates that the preparation process successfully constructed a microscopic composite interface of mineral-bridging agent-organic fertilizer, rather than a simple physical mixture.

[0063] Figure 4 The following are FTIR images of expanded modified vermiculite (a), decomposed cow manure (b), galactitol (c), and soil amendment (d) in Example 1. Figure 4 It can be seen that the soil amendment material in Example 1 has a wavenumber of 3249.4 cm⁻¹. -1 A broad peak appeared at the point, which corresponds to the stretching vibration of hydroxyl groups in multiple hydrogen bond association. This characteristic peak is not present in the raw materials, expanded modified vermiculite and decomposed cow manure. This directly confirms that the hydroxyl groups of the galactitol bridging agent form a strong hydrogen bond network with the active functional groups such as Si-OH / Al-OH on the mineral surface and carboxyl / amino groups in the organic fertilizer. This hydrogen bond network cannot be formed by simply physically mixing expanded modified vermiculite and decomposed cow manure.

[0064] In Example 2, perlite was subjected to instantaneous high-temperature heat treatment, causing the internal bound water to vaporize and burst, forming a porous structure in the expanded modified perlite, reducing its bulk density to 80 kg / m³. 3 Scanning electron microscopy and Fourier transform infrared spectroscopy characterization results show that although the layer charge density of perlite is slightly lower than that of vermiculite, the rich macroporous structure of expanded modified perlite is also filled with organic fertilizer, forming a similar encapsulation and anchoring, and successfully constructing a hydrogen bond network structure similar to that in Example 1.

[0065] In Example 3, mannitol was used as a bridging agent to connect expanded modified vermiculite and decomposed manure. Mannitol and galactitol are isomers with similar polyhydroxy structures. The scanning electron microscopy and Fourier transform infrared spectroscopy characterization results showed that the microstructure and FTIR spectral characteristic peaks of the soil amendment material in Example 3 were highly similar to those in Example 1, which means that mannitol has an equivalent ability to bridge and construct composite structures.

[0066] The characterization results in Examples 2 and 3 demonstrate that different expanded modified layered silicate minerals and different polysaccharide alcohols can successfully construct similar hydrogen bond networks, and the hydrogen bond network construction mechanism on which the soil amendment material preparation method provided by the present invention relies has universality.

[0067] In Example 4, the amount of composted cow manure and galactitol was reduced. The scanning electron microscope and Fourier transform infrared spectroscopy characterization results showed that the coverage of composted cow manure on the surface of expanded modified vermiculite was not as dense and continuous as in Example 1. However, the adhesion of composted cow manure on the surface of expanded modified vermiculite could still be seen. Hydrogen bond characteristic peaks could still be observed in the FTIR spectrum, but the peak intensity was relatively weak. This proved that the reduction in the amount of polyols would lead to a decrease in the density of the hydrogen bond network. However, even with a low addition amount, the bridging mechanism was still effective.

[0068] Application effect test of soil amendment materials The effectiveness of soil amendment materials was verified through a pot experiment. Specifically, topsoil (0-20cm) from paddy fields was collected, air-dried, and sieved through a 2mm sieve. 5kg of dry soil was placed in each of 15 plastic pots (19cm in diameter, 20cm in height), and the pots were randomly divided into 5 treatment groups (3 pots per group). Different soil amendment materials were applied to each treatment group and thoroughly mixed with the soil. Treatment group 1: No soil amendment materials were applied, serving as a blank control; Treatment group 2: The soil amendment material prepared in Comparative Example 1 was applied; Treatment Group 3: Commercially available rice husk char-based soil conditioner was applied as a soil amendment material. This rice husk char-based soil conditioner is agricultural rice husk biochar produced by Liaoning Jinhefu Agricultural Technology Co., Ltd. It is made from pure rice husks as raw materials and prepared by oxygen-limited pyrolysis at about 500°C. Due to the natural silica layer on the surface, its specific surface area is small and its bulk density is extremely low (it is easy to float and be lost).

[0069] Treatment group 4: Apply the soil amendment material prepared in Example 1; Treatment group 5: Apply the soil amendment material prepared in Example 2; In treatment groups 2-5, the amount of soil amendment material applied was 100g / pot. In addition, in treatment groups 1-5, equal amounts of urea, superphosphate and potassium chloride were applied as base fertilizer.

[0070] After transplanting rice seedlings into plastic pots in each of the above treatment groups, the water level was maintained at 5 cm for 95 days (flooding period), followed by drainage for 25 days (drainage period), and the following indicators were measured: (1) Greenhouse gases: Gases were collected on days 0, 15, 40, 65 and 95 of the flooding period and on days 7 and 25 of the drainage period using static dark chamber gas chromatography to determine the emission fluxes of CH4 and N2O. (2) Soil nitrogen: Soil samples were collected on days 0, 15, 40, 65 and 95 of the flooding period, and on days 7 and 25 of the drainage period. The samples were extracted with 1 mol / L KCl and the NH4 content of the soil was determined by a flow analyzer. + content; (3) Microbial diversity analysis: Soil samples were collected on days 0 and 95 of the flooding period and day 25 of the drainage period. Using a commercial soil genomic DNA extraction kit, microbial cells were lysed from the soil, and the mixed genomic DNA of all microorganisms was extracted and purified. The PCR amplicon of the V3-V4 region of the bacterial 16S rRNA gene was sequenced, and potential functional bacterial groups related to methane and nitrate were detected at the genus level to obtain the relative abundance data of related functional bacteria.

[0071] Table 2. Cumulative CH4 and N2O emissions of different treatment groups on day 95 of the flooding period

[0072] Table 2 shows the cumulative CH4 and N2O emissions of different treatment groups on day 95 of the flooding period. As shown in Table 2, the cumulative CH4 and N2O emissions of treatment group 2 on day 95 of the flooding period were higher than those of treatment group 1. This verifies that the mineral-organic fertilizer composite material prepared solely through simple physical mixing not only fails to construct a stable composite system but also releases more CH4 and N2O in a short period due to the rapid decomposition of organic matter. In treatment group 3, the biochar-based soil conditioner has a certain effect on reducing CH4 and N2O emissions, but due to insufficient surface chemically active sites, its effect is limited as it relies solely on adsorption. The cumulative emissions of CH4 and N2O in treatment group 4 were significantly lower than those in the other treatment groups. Compared with treatment group 1 (blank control), the cumulative emission reduction rates of CH4 and N2O on day 95 of the flooding period reached 22.0% and 67.8%, respectively. This indicates that the soil amendment material prepared in Example 1 can effectively reduce the emission of CH4 and N2O in flooded soil, and its effect is better than that of the soil amendment material prepared by simple physical mixing (treatment group 2) and the commercially available biochar-based soil amendment (treatment group 3). It builds a stable chemical bonding network through hydrogen bonding, overcoming the defects of existing soil amendment materials.

[0073] Figure 5 This is a comparison of CH4 and N2O emission fluxes between treatment group 1 and treatment group 4 in a pot experiment. Figure 5 (a) in the figure is a comparison of instantaneous CH4 emission fluxes. Figure 5 (b) in the figure is a comparison of instantaneous N2O emission flux. Figure 5 (c) in the figure is a comparison of cumulative CH4 emission fluxes. Figure 5 (d) in the figure is a comparison of cumulative N2O emission fluxes. Identical lowercase letters in the figure represent no significant difference. p >0.05, independent samples t-test), different lowercase letters represent significant differences ( p <0.05, independent samples t-test), by Figure 5 It can be seen that at the end of the pot experiment, the cumulative emission flux of CH4 and N2O in treatment group 4 was significantly lower than that in treatment group 1, indicating that the soil amendment material prepared in Example 1 can effectively reduce the emission of CH4 and N2O in flooded paddy field soil, and that the soil amendment material can continuously and stably suppress emission peaks throughout the entire experimental period, rather than having a short-term effect.

[0074] Figure 6 Soil-extracted NH4 from treatment groups 1 and 4 in the pot experiment + Content change, from Figure 6It can be seen that on the 65th day of the flooding period (mid-growth stage of rice), the soil extractable NH4 in treatment group 4 was... + The nitrogen content remained at 4.6 mg / kg, while in treatment group 1 it was only 1.1 mg / kg. This indicates that the soil amendment prepared in Example 1 has excellent nitrogen retention and slow-release capabilities. This is attributed to the large specific surface area and ion exchange capacity of the expanded modified vermiculite, which can strongly adsorb NH4 in the soil. + Some NH4 + Even NH4 is fixed within its crystal lattice, adsorbed / fixed. + Slow release reduces the available substrate for nitrifying bacteria, thereby directly inhibiting nitrification (the production of NH3). - This includes the potential subsequent denitrification (producing N2O), and the hydrogen bond network also slows down the mineralization rate of organic nitrogen, thus controlling NH4 at its source. + The formation rate of the modified vermiculite, together with its adsorption capacity, forms a synergistic nitrogen retention system of slow supply and stable storage, which enhances the soil's nitrogen retention capacity. This not only meets the growth needs of crops in the later stages but also reduces the risk of rapid nitrogen loss and conversion into N2O.

[0075] Figure 7 The figure shows the relative abundance of *Methanogens* (a) and *Pseudomonas* (b) in soil samples from treatment groups 1 and 4 in a pot experiment. Identical lowercase letters in the figure represent no significant difference. p >0.05, independent samples t-test), different lowercase letters represent significant differences ( p <0.05, independent samples t-test), by Figure 7 It can be seen that on the 95th day of the flooding period, the genus *Methanobacterium* (with methanogenic function) in the soil of treatment group 4... Methanobacterium ), and Pseudomonas spp., which have nitrate-reducing functions ( Pseudomonas The relative abundance of the organic fertilizer was significantly lower than that of treatment group 1, indicating that the soil amendment material prepared in Example 1, due to the dense hydrogen bond network and mineral layer physical encapsulation of the organic fertilizer, greatly limited the direct contact between the methanogenic bacteria, nitrate-reducing bacteria and their secreted enzymes and the organic carbon substrate in the soil. The hydrogen bond network changed the physicochemical state of organic carbon, making it difficult for microbial enzyme systems to recognize and decompose it, significantly reducing the bioavailability of organic carbon, inhibiting the activity and reproduction of key functional microorganisms responsible for producing CH4 and participating in the nitrification-denitrification process, thereby effectively inhibiting the methanogenic process and the nitrification-denitrification process, reducing soil CH4 and N2O emissions, and promoting the formation of stable organic matter.

Claims

1. A soil amendment material, characterized in that, By mass percentage, the raw materials include: 40%-70% expanded modified layered silicate minerals, 20%-55% organic fertilizer, and 1%-10% polysaccharide alcohols.

2. The soil amendment material according to claim 1, characterized in that, The expanded modified layered silicate minerals are obtained by instantaneous heat treatment of expanded layered silicate minerals.

3. The soil amendment material according to claim 2, characterized in that, The expansive layered silicate minerals include at least one of vermiculite, perlite, bentonite, montmorillonite, and rettoite.

4. The soil amendment material according to claim 2, characterized in that, The instantaneous heat treatment is performed at a temperature of 800-950℃ for a duration of 10-60 seconds.

5. The soil amendment material according to claim 1, characterized in that, The organic fertilizer includes at least one of decomposed livestock and poultry manure and fermented plant residues.

6. The soil amendment material according to claim 1, characterized in that, The polyols include at least one of galactitol, mannitol, sorbitol, xylitol, and erythritol.

7. The method for preparing the soil amendment material according to any one of claims 1-6, characterized in that, Includes the following steps: The expanded modified layered silicate minerals were mixed with organic fertilizer, and an aqueous solution of polysaccharide alcohol was applied to the surface of the resulting mixture for maturation to obtain the soil amendment material.

8. The preparation method according to claim 7, characterized in that, The ripening temperature is ≤60℃ and the time is 10-24h.

9. The soil amendment material according to any one of claims 1-6, in any of the following applications: a. Reduce greenhouse gas emissions from soil; b. Improve soil nitrogen retention capacity; c. Improve soil physical structure; d. Increase soil organic matter content.

10. The application according to claim 9, characterized in that, The greenhouse gas includes at least one of methane and nitrous oxide.

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