Degenerated soil capacity expansion conditioner and application method

Abstract

The invention discloses a degraded soil dilatation conditioning agent and an application method, and belongs to the technical field of soil dilatation conditioning. The conditioner is composed of an organic fertilizer and one of woody peat or biomass charcoal. The organic fertilizer is prepared by fermenting livestock and poultry manure and straw through a complex microbial inoculant and then adding modified montmorillonite for further decomposition; the modified montmorillonite is prepared by nitrogen doping, alkalization, quaternization, graft polymerization with itaconic acid and acrylic acid and loading of tea saponin, and has high specific surface area and excellent nutrient adsorption and slow release functions. According to the application method, the conditioner and the compound fertilizer are used as base fertilizer and ploughed into soil before rice transplanting. According to the invention, through scientific combined application of the active organic material and the inert organic material, and bridging and regulation of the functional modified montmorillonite, short-term rapid supply of nutrients in degraded soil and long-term stable solid storage of organic carbon are realized, and systematic recovery of soil structure, fertility and microbial activity is effectively promoted, so that the crop yield is increased.

Description

Technical Field

[0001] This invention belongs to the field of soil expansion and conditioning technology, and particularly relates to a degraded soil expansion and conditioning agent and its application method. Background Technology

[0002] Against the backdrop of escalating global food security pressures, the conversion of arable land to non-grain uses has become a key issue hindering sustainable agricultural development. Non-grain production refers to the conversion of arable land from food use to non-grain uses such as cash crops or livestock and aquaculture. While this satisfies market-oriented and diversified consumption demands, its continued expansion is weakening the basic food security function of arable land. China possesses only about 9% of the world's arable land resources, yet it must feed approximately 21% of the population, resulting in a particularly acute conflict between population and land. Between 2000 and 2021, China's non-grain crop planting area increased by 7.0%, leading to a 22.6% decrease in total primary productivity of arable land. To restore the food function of arable land, China implemented a "non-grain land reclamation" policy in 2020. However, reclamation faces obstacles such as soil organic matter depletion, degradation of soil aggregate structure, insufficient nutrient supply, and reduced microbial activity, severely limiting soil function restoration and the release of crop production potential. Therefore, promoting the systematic restoration of soil quality in non-grain land reclamation has become a core task for ensuring arable land's food production capacity and achieving sustainable agricultural development. However, current research focuses on improving the physical and chemical properties of reclaimed land, and there is still a lack of systematic understanding of the overall soil function, especially the synergistic restoration of fertility and carbon sequestration capacity.

[0003] Organic materials, as commonly used soil conditioners, are widely applied to the quality restoration of degraded farmland. Their effectiveness is influenced by their stability and nutrient supply capacity. Existing degraded farmland restoration technologies typically employ a single type of organic material (such as applying organic fertilizer or biochar alone), which has the following limitations: Active organic materials (such as livestock manure and green manure) can rapidly increase nutrient levels and significantly promote crop growth in the short term, but their unstable carbon components can easily exacerbate carbon mineralization and greenhouse gas emissions, posing a high risk of carbon loss. While biochar can improve soil carbon stability, its nutrient supply capacity is weak, resulting in limited improvement in soil fertility after application. Woody peat is a new, low-cost natural organic conditioner with carbon stability between organic fertilizer and biochar. Rich in humus and nutrients, it can improve soil structure and slowly release nutrients. However, its excessively high C / N ratio (approximately 100:1) may initially trigger intense competition for nitrogen among microorganisms, inhibiting crop growth and accompanied by a stimulating effect. In summary, different organic materials have distinct functional characteristics, making it difficult to synergistically enhance the carbon sequestration and fertilization functions of non-grain farmland. Therefore, constructing a reasonable application strategy, leveraging the complementarity between materials, and achieving a synergistic improvement in both rapid short-term nutrient supply and long-term stable carbon pool are key pathways for improving soil quality in non-grain farmland recultivation. Summary of the Invention

[0004] In response to the above situation and to overcome the shortcomings of existing technologies, this invention scientifically combines organic fertilizer prepared by a specific process with one of woody peat or biochar. Multifunctional modified montmorillonite is introduced into the preparation of organic fertilizer to achieve a synergistic improvement in efficient short-term nutrient supply and stable long-term organic carbon sequestration, thereby systematically restoring the soil quality of non-grain-producing land and restoring its grain production potential.

[0005] To achieve the above objectives, the following technical solution is adopted: This invention provides a degraded soil expansion conditioner, which is composed of organic fertilizer and one of woody peat or biochar.

[0006] Furthermore, the organic fertilizer is prepared through the following steps:

[0007] S1 selects livestock and poultry manure and crop straw as raw materials, crushes the straw to 2-5cm, and then mixes it with livestock and poultry manure at a mass ratio of 1:2-1:3, adjusting the moisture content of the mixture to 55%-65%;

[0008] S2. Add compound microbial agent to the mixture, stir evenly, and then pile it into a fermentation pile with a height of 1.0-1.5m and a width of 2.0-3.0m;

[0009] S3. For the first 1-3 days, control the pile temperature at 30-40℃. On the 4th day, start turning the pile, and then turn it every 2 days thereafter, keeping the pile temperature at 55-65℃. Continue fermentation for 15 days, then add modified montmorillonite and mix evenly. The mass ratio of modified montmorillonite to the basic composted material is 0.03:1-0.05:1. Continue fermentation for 5 days, then let it cool naturally to obtain the composted material.

[0010] S4. Crush the decomposed material, pass it through an 80-mesh sieve to remove impurities, dry it in an 80-90℃ oven until the moisture content is ≤15%, crush it again and pass it through a 100-mesh sieve to obtain the finished organic fertilizer.

[0011] Further, the modified montmorillonite is prepared by the following steps: nitrogen doping and alkalization of montmorillonite to obtain alkalized montmorillonite; ultrasonic dispersion of alkalized montmorillonite in deionized water to obtain a suspension; addition of oleo-di(2-hydroxyethyl)methylammonium chloride to the suspension and reaction at 50-60℃ for 4-6 hours; then itaconic acid, acrylic acid, N,N-dimethylformamide, crosslinking agent and initiator are added to the system in sequence; the temperature is raised to 70-80℃ and stirred at a constant temperature for 6-8 hours; after the reaction is completed, the temperature is cooled to 40-50℃; tea saponin is added and stirred at a constant temperature for 1-2 hours; then ultrasonic dispersion, filtration, washing, drying, pulverizing and sieving are performed to obtain the modified montmorillonite product.

[0012] When nitrogen-doping natural montmorillonite is performed, nitrogen is successfully introduced into the montmorillonite crystal structure through a high-temperature calcination process using urea as the nitrogen source. This not only significantly increases the nitrogen content of montmorillonite, providing a stable nitrogen reserve for soil and crops, but also optimizes the surface electronic structure of montmorillonite, enhancing its adsorption affinity for polar nutrients. Subsequent alkalization treatment, using sodium hydroxide solution, effectively removes impurities from the montmorillonite surface and causes moderate expansion of the montmorillonite crystal lattice, exposing a large number of surface hydroxyl groups. These hydroxyl groups serve as active sites, providing ample reaction sites for subsequent quaternization modification and graft polymerization reactions, thus improving the modification activity and reaction efficiency of montmorillonite.

[0013] Further, the mass concentration of the alkalized montmorillonite suspension is 5%-8%, the mass ratio of oleo-based di(2-hydroxyethyl)methylammonium chloride to alkalized montmorillonite is 0.1:1-0.2:1; the mass ratio of itaconic acid to acrylic acid is 1:2-1:3; the mass ratio of the total mass of itaconic acid and acrylic acid to the mass of alkalized montmorillonite is 0.5:1-0.8:1; and the amount of N,N-dimethylformamide used is 5%-8% of the total mass of itaconic acid and acrylic acid.

[0014] Further, the crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 1%-2% of the total mass of itaconic acid and acrylic acid; the initiator is selected from one of ammonium persulfate, potassium persulfate, and benzoyl peroxide, and the amount of the initiator is 0.5%-1% of the total mass of itaconic acid and acrylic acid; the mass ratio of tea saponin to alkalized montmorillonite is 0.05-0.1:1.

[0015] Furthermore, the compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, and Bacillus mucilaginosa, and the total viable count of the compound microbial agent is not less than 1.0 × 10⁻⁶. 9 FU / g, wherein the amount of the compound microbial agent added is 0.1%-0.2% of the total mass of the mixture.

[0016] Further, the nitrogen doping and alkalization treatment specifically includes: taking natural montmorillonite, drying it at 100-110℃ for 4-6 hours to remove free moisture, pulverizing it and passing it through a 200-mesh sieve to obtain refined montmorillonite powder, uniformly mixing the refined montmorillonite powder with urea, placing it in a tube furnace, and heating it to 500-600℃ at a heating rate of 5-8℃ / min under a nitrogen protective atmosphere, calcining it at a constant temperature for 2-3 hours, and naturally cooling it to room temperature after calcination to obtain nitrogen-doped montmorillonite; adding the nitrogen-doped montmorillonite to a sodium hydroxide solution, stirring and reacting it at a solid-liquid ratio under a constant temperature water bath at 60-70℃ for 2-3 hours, cooling the system to room temperature after the reaction, washing it with deionized water until the pH of the washing solution is 7-8, filtering it, and drying the filter cake in a 105℃ oven for 8-10 hours, pulverizing it and passing it through a 200-mesh sieve to obtain alkalized montmorillonite.

[0017] Furthermore, the refined montmorillonite and urea are uniformly mixed at a mass ratio of 1:3 to 1:5, the mass concentration of the sodium hydroxide solution is 8% to 12%, and the solid-liquid ratio of the nitrogen-doped montmorillonite to the sodium hydroxide solution is 1g:10-15mL.

[0018] Furthermore, the application rate of each component in the conditioner is: 15000 kg·hm² of organic fertilizer. -2 Woody peat 5898.8 kg·hm -2 Biochar 6275.6 kg·hm -2 .

[0019] On the other hand, the present invention also provides a method for applying a low-dose soil conditioner for degraded soil, the steps of which include: applying the conditioner together with compound fertilizer as base fertilizer before rice transplanting, mixing the fertilizer with the soil by tilling, the tilling depth being 15cm, and not applying topdressing during the rice growth period.

[0020] When conditioners are applied to degraded soils, the layered structure and porous nature of modified montmorillonite improves soil particle aggregation, reduces compaction, increases porosity, and enhances the soil's water and fertilizer retention capacity. The organic carbon replenishment and efficient nutrient supply from the combined application system increase soil organic matter content, optimize microbial community structure, and activate soil enzyme activity, comprehensively improving soil fertility. A favorable soil environment provides suitable conditions for rice root growth, promotes photosynthesis and nutrient absorption, and significantly increases rice yield.

[0021] Furthermore, the compound fertilizer contains 15% total nitrogen, 15% available phosphorus, and 15% potassium, and the application rate is 600 kg·hm². -2 .

[0022] The beneficial effects of this invention are:

[0023] This invention introduces oil-based di(2-hydroxyethyl)methylammonium chloride into alkalized montmorillonite. The steric hindrance effect of the quaternary ammonium salt groups effectively expands the layered structure of montmorillonite and increases the interlayer spacing, providing ample space for nutrient adsorption. Simultaneously, the quaternary ammonium salt cations can adsorb free nitrate and phosphate anions in the soil through electrostatic attraction, reducing nutrient leaching and improving nutrient retention. Under the action of crosslinking agents and initiators, itaconic acid and acrylic acid undergo graft polymerization with montmorillonite, forming a three-dimensional crosslinked polymer network structure. This expands the pore size of montmorillonite, increases the specific surface area and ammonia nitrogen adsorption activity of the composite material, and avoids organic matter... During the fermentation of organic fertilizer, ammonia nitrogen is lost through volatilization. The carboxyl groups introduced through grafting can efficiently adsorb tea saponins. Quaternary ammonium salt groups and saponins form a stable bond through hydrophobic and electrostatic interactions, enhancing the retention effect of saponins and synergistically strengthening the activity of beneficial soil microorganisms, thus promoting nutrient conversion. Modified montmorillonite can efficiently adsorb ammonia nitrogen in the leachate of organic fertilizer microbial agents, precisely adjusting the carbon-nitrogen ratio of organic fertilizer to a suitable range for soil microorganisms and crop growth, promoting the decomposition and nutrient conversion of organic fertilizer, avoiding nutrient fixation or loss caused by carbon-nitrogen imbalance, and improving the release efficiency of nutrients such as nitrogen, phosphorus, and potassium, providing crops with a continuous and stable nutrient supply.

[0024] The combined application system of reducing active organic materials (organic fertilizer) and supplementing with inert organic materials (woody peat or biochar) can overcome the contradiction that active materials are prone to carbon loss but provide fertilizer quickly, while inert materials have strong carbon sequestration but provide fertilizer slowly. The nutrient retention effect of modified montmorillonite can ensure the nutrient requirements of crops while reducing the amount of organic fertilizer applied, and reduce the loss of organic carbon and carbon emissions during the decomposition of active materials. Woody peat or biochar can stably seal organic carbon for a long time and increase the soil carbon pool. Its porous structure can adsorb soil nutrients and water, improve aeration and permeability, and the small amount of nutrients it carries can be slowly released to make up for the short-term insufficient fertilizer supply after the reduction of active materials, thus achieving the synergy of slow fertilizer supply and carbon stabilization. Attached Figure Description

[0025] Figure 1 This invention illustrates the effects of different stable organic materials applied in combination on soil chemical properties and their stoichiometry, where different lowercase letters represent significant differences between different treatments (P<0.05). Figure 1 The data are expressed as mean ± standard deviation (n=3);

[0026] Figure 2This invention illustrates the effects of different stable organic materials applied in combination on rice yield, overall soil fertility, and cumulative mineralization. Different lowercase letters represent significant differences between treatments (P < 0.05). Data in the figure are mean ± standard deviation (n = 3); BG: β-glucosidase; CB: cellobiose hydrolase; PPO: phenol oxidase; CAT: catalase; LAP: leucine aminopeptidase; NAG: acetylglucosidase; GMea: geometric mean of enzymes; OX: HY enzyme: oxidase / hydrolase ratio; LCI: lignin index.

[0027] Figure 3 The effect of different stable organic materials applied in combination on soil enzyme activity is shown in this invention. Different lowercase letters represent significant differences between different treatments (P<0.05); the data in the figure are mean ± standard deviation (n=3).

[0028] Figure 4 The effect of different stable organic materials applied in combination on soil microbial metabolism is shown in this invention. Different lowercase letters represent significant differences between different treatments (P<0.05); the data in the figure are mean ± standard deviation (n=3).

[0029] Figure 5 The effect of applying different stable organic materials on the functional groups of soil organic carbon is shown in this invention. Different lowercase letters represent significant differences between different treatments (P<0.05); the data in the figure are mean ± standard deviation (n=3).

[0030] Figure 6 This invention illustrates the effects of applying organic materials with different stability on key physical indicators such as soil aggregate stability, porosity, and bulk density. Different lowercase letters represent significant differences between different treatments (P<0.05); the data in the figure are mean ± standard deviation (n=3).

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0035] Example 1:

[0036] A degraded soil volume-expanding conditioner, the conditioner being composed of organic fertilizer and woody peat, with the following application rates: organic fertilizer 15000 kg·hm² -2 Woody peat 5898.8 kg·hm -2 .

[0037] The organic fertilizer is prepared through the following steps:

[0038] S1 selects livestock and poultry manure and crop straw as raw materials, crushes the straw to 2cm, and then mixes it with livestock and poultry manure at a mass ratio of 1:2, adjusting the moisture content of the mixture to 55%;

[0039] S2. Add compound microbial agent to the mixture, stir evenly, and then pile it into a fermentation pile with a height of 1.0m and a width of 2.0m;

[0040] S3. Control the pile temperature at 30℃ for the first 1-3 days. Start turning the pile on the 4th day and turn it every 2 days thereafter, keeping the pile temperature at 55℃. Continue fermentation for 15 days, then add modified montmorillonite and mix evenly. The mass ratio of modified montmorillonite to the basic composted material is 0.03:1. Continue fermentation for 5 days, then let it cool naturally to obtain the composted material.

[0041] S4. Crush the decomposed material, pass it through an 80-mesh sieve to remove impurities, dry it in an 80℃ oven until the moisture content is ≤15%, crush it again and pass it through a 100-mesh sieve to obtain the finished organic fertilizer.

[0042] The modified montmorillonite is prepared by the following steps: nitrogen doping and alkalization of montmorillonite to obtain alkalized montmorillonite; ultrasonic dispersion of alkalized montmorillonite in deionized water to obtain a suspension; addition of oleo-di(2-hydroxyethyl)methylammonium chloride to the suspension and reaction at 50°C for 4 hours; then itaconic acid, acrylic acid, N,N-dimethylformamide, crosslinking agent and initiator are added to the system in sequence; the temperature is raised to 70°C and stirred at a constant temperature for 6 hours; after the reaction is completed, the temperature is cooled to 40°C; tea saponin is added and stirred at a constant temperature for 1 hour; then ultrasonic dispersion, filtration, washing, drying, pulverizing and sieving are performed to obtain the modified montmorillonite product.

[0043] The mass concentration of the alkalized montmorillonite suspension is 5%, and the mass ratio of oil-based di(2-hydroxyethyl)methylammonium chloride to alkalized montmorillonite is 0.1:1; the mass ratio of itaconic acid to acrylic acid is 1:2; the mass ratio of the total mass of itaconic acid and acrylic acid to the mass of alkalized montmorillonite is 0.5:1; and the amount of N,N-dimethylformamide used is 5% of the total mass of itaconic acid and acrylic acid.

[0044] The crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 1% of the total mass of itaconic acid and acrylic acid; the initiator is selected from one of ammonium persulfate, potassium persulfate, and benzoyl peroxide, and the amount of the initiator is 0.5% of the total mass of itaconic acid and acrylic acid; the mass ratio of tea saponin to alkalized montmorillonite is 0.05:1.

[0045] The compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, and Bacillus mucilaginosa, and the total viable count of the compound microbial agent is not less than 1.0 × 10⁻⁶. 9 FU / g, wherein the amount of the compound microbial agent added is 0.1% of the total mass of the mixture.

[0046] The nitrogen doping and alkalization treatment specifically includes: taking natural montmorillonite, drying it at 100℃ for 4 hours to remove free moisture, pulverizing it and passing it through a 200-mesh sieve to obtain refined montmorillonite powder, uniformly mixing the refined montmorillonite powder with urea, placing it in a tube furnace, and calcining it at a heating rate of 5℃ / min to 500℃ under a nitrogen protective atmosphere for 2 hours. After calcination, it is naturally cooled to room temperature to obtain nitrogen-doped montmorillonite; adding the nitrogen-doped montmorillonite to a sodium hydroxide solution, stirring and reacting it at a solid-liquid ratio under a constant temperature water bath at 60℃ for 2 hours, after the reaction, cooling the system to room temperature, washing it with deionized water until the pH of the washing solution is 7, filtering it, and drying the filter cake in a 105℃ oven for 8 hours, pulverizing it and passing it through a 200-mesh sieve to obtain alkalized montmorillonite.

[0047] The refined montmorillonite and urea are uniformly mixed at a mass ratio of 1:3. The mass concentration of the sodium hydroxide solution is 8%. The solid-liquid ratio of the nitrogen-doped montmorillonite to the sodium hydroxide solution is 1g:10mL.

[0048] Example 2:

[0049] A degraded soil volume-expanding conditioner, the conditioner being composed of organic fertilizer and woody peat, with the following application rates: organic fertilizer 15000 kg·hm² -2 Woody peat 5898.8 kg·hm -2 .

[0050] The organic fertilizer is prepared through the following steps:

[0051] S1 selects livestock and poultry manure and crop straw as raw materials, crushes the straw to 5cm, and then mixes it with livestock and poultry manure at a mass ratio of 1:3, adjusting the moisture content of the mixture to 65%;

[0052] S2. Add compound microbial agent to the mixture, stir evenly, and then pile it into a fermentation pile with a height of 1.5m and a width of 3.0m;

[0053] S3. Control the pile temperature at 40℃ for the first 1-3 days. Start turning the pile on the 4th day and turn it every 2 days thereafter, keeping the pile temperature at 65℃. Continue fermentation for 15 days, then add modified montmorillonite and mix evenly. The mass ratio of modified montmorillonite to the basic composted material is 0.05:1. Continue fermentation for 5 days, then let it cool naturally to obtain the composted material.

[0054] S4. Crush the decomposed material, pass it through an 80-mesh sieve to remove impurities, dry it in a 90℃ oven until the moisture content is ≤15%, crush it again and pass it through a 100-mesh sieve to obtain the finished organic fertilizer.

[0055] The modified montmorillonite is prepared through the following steps: montmorillonite is nitrogen-doped and alkalized to obtain alkalized montmorillonite; the alkalized montmorillonite is added to deionized water and ultrasonically dispersed to obtain a suspension; oleo-di(2-hydroxyethyl)methylammonium chloride is added to the suspension and reacted at 60°C for 6 hours; then itaconic acid, acrylic acid, N,N-dimethylformamide, crosslinking agent and initiator are added to the system in sequence; the temperature is raised to 80°C and stirred at a constant temperature for 8 hours; after the reaction is completed, the temperature is cooled to 50°C; tea saponin is added and stirred at a constant temperature for 2 hours; then the mixture is ultrasonically dispersed, filtered, washed, dried, pulverized and sieved to obtain the modified montmorillonite product.

[0056] The mass concentration of the alkalized montmorillonite suspension is 8%, the mass ratio of oil-based di(2-hydroxyethyl)methylammonium chloride to alkalized montmorillonite is 0.2:1; the mass ratio of itaconic acid to acrylic acid is 1:3; the mass ratio of the total mass of itaconic acid and acrylic acid to the mass of alkalized montmorillonite is 0.8:1; and the amount of N,N-dimethylformamide used is 8% of the total mass of itaconic acid and acrylic acid.

[0057] The crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 2% of the total mass of itaconic acid and acrylic acid; the initiator is selected from one of ammonium persulfate, potassium persulfate, and benzoyl peroxide, and the amount of the initiator is 1% of the total mass of itaconic acid and acrylic acid; the mass ratio of tea saponin to alkalized montmorillonite is 0.1:1.

[0058] The compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, and Bacillus mucilaginosa, and the total viable count of the compound microbial agent is not less than 1.0 × 10⁻⁶. 9FU / g, wherein the amount of the compound microbial agent added is 0.2% of the total mass of the mixture.

[0059] The nitrogen doping and alkalization treatment specifically includes: taking natural montmorillonite, drying it at 110℃ for 6 hours to remove free moisture, pulverizing it and passing it through a 200-mesh sieve to obtain refined montmorillonite powder, uniformly mixing the refined montmorillonite powder with urea, placing it in a tube furnace, and calcining it at a heating rate of 8℃ / min to 600℃ under a nitrogen protective atmosphere for 3 hours. After calcination, it is naturally cooled to room temperature to obtain nitrogen-doped montmorillonite; adding the nitrogen-doped montmorillonite to a sodium hydroxide solution, stirring and reacting it at a solid-liquid ratio under a constant temperature water bath at 70℃ for 3 hours, cooling the system to room temperature after the reaction, washing it with deionized water until the pH of the washing solution is 8, filtering it, and drying the filter cake in a 105℃ oven for 10 hours, pulverizing it and passing it through a 200-mesh sieve to obtain alkalized montmorillonite.

[0060] The refined montmorillonite and urea are uniformly mixed at a mass ratio of 1:5. The mass concentration of the sodium hydroxide solution is 12%. The solid-liquid ratio of the nitrogen-doped montmorillonite to the sodium hydroxide solution is 1g:15mL.

[0061] Example 3:

[0062] A degraded soil volume-expanding conditioner, the conditioner being composed of organic fertilizer and woody peat, with the following application rates: organic fertilizer 15000 kg·hm² -2 Woody peat 5898.8 kg·hm -2 .

[0063] The organic fertilizer is prepared through the following steps:

[0064] S1 selects livestock and poultry manure and crop straw as raw materials, crushes the straw to 3.5cm, and then mixes it with livestock and poultry manure at a mass ratio of 1:2.5, adjusting the moisture content of the mixture to 60%.

[0065] S2. Add compound microbial agent to the mixture, stir evenly, and then pile it into a fermentation pile with a height of 1.3m and a width of 2.5m;

[0066] S3. Control the pile temperature at 35℃ for the first 1-3 days. Start turning the pile on the 4th day and turn it every 2 days thereafter, keeping the pile temperature at 60℃. Continue fermentation for 15 days, then add modified montmorillonite and mix evenly. The mass ratio of modified montmorillonite to the basic composted material is 0.04:1. Continue fermentation for 5 days, then let it cool naturally to obtain the composted material.

[0067] S4. Crush the decomposed material, pass it through an 80-mesh sieve to remove impurities, dry it in an 85℃ oven until the moisture content is ≤15%, crush it again and pass it through a 100-mesh sieve to obtain the finished organic fertilizer.

[0068] The modified montmorillonite is prepared through the following steps: montmorillonite is nitrogen-doped and alkalized to obtain alkalized montmorillonite; the alkalized montmorillonite is added to deionized water and ultrasonically dispersed to obtain a suspension; oleo-di(2-hydroxyethyl)methylammonium chloride is added to the suspension and reacted at 55°C for 5 hours; then itaconic acid, acrylic acid, N,N-dimethylformamide, crosslinking agent and initiator are added to the system sequentially; the temperature is raised to 75°C and stirred at a constant temperature for 7 hours; after the reaction is completed, the temperature is cooled to 45°C; tea saponin is added and stirred at a constant temperature for 1.5 hours; then the mixture is ultrasonically dispersed, filtered, washed, dried, pulverized and sieved to obtain the modified montmorillonite product.

[0069] The mass concentration of the alkalized montmorillonite suspension is 6.5%, and the mass ratio of oil-based di(2-hydroxyethyl)methylammonium chloride to alkalized montmorillonite is 0.15:1; the mass ratio of itaconic acid to acrylic acid is 1:2.5; the mass ratio of the total mass of itaconic acid and acrylic acid to the mass of alkalized montmorillonite is 0.65:1; and the amount of N,N-dimethylformamide used is 6.5% of the total mass of itaconic acid and acrylic acid.

[0070] The crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 1.5% of the total mass of itaconic acid and acrylic acid; the initiator is selected from one of ammonium persulfate, potassium persulfate, and benzoyl peroxide, and the amount of the initiator is 0.75% of the total mass of itaconic acid and acrylic acid; the mass ratio of tea saponin to alkalized montmorillonite is 0.075:1.

[0071] The compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, and Bacillus mucilaginosa, and the total viable count of the compound microbial agent is not less than 1.0 × 10⁻⁶. 9 FU / g, wherein the amount of the compound microbial agent added is 0.15% of the total mass of the mixture.

[0072] The nitrogen doping and alkalization treatment specifically includes: taking natural montmorillonite, drying it at 105℃ for 5 hours to remove free moisture, pulverizing it and passing it through a 200-mesh sieve to obtain refined montmorillonite powder, uniformly mixing the refined montmorillonite powder with urea, placing it in a tube furnace, and calcining it at a heating rate of 6.5℃ / min to 550℃ under a nitrogen protective atmosphere for 2.5 hours. After calcination, it is naturally cooled to room temperature to obtain nitrogen-doped montmorillonite; adding the nitrogen-doped montmorillonite to a sodium hydroxide solution, stirring and reacting it at a solid-liquid ratio under a constant temperature water bath at 65℃ for 2.5 hours, cooling the system to room temperature after the reaction, washing it with deionized water until the pH of the washing solution is 7.5, filtering it, and drying the filter cake in a 105℃ oven for 9 hours, pulverizing it and passing it through a 200-mesh sieve to obtain alkalized montmorillonite.

[0073] The refined montmorillonite and urea are uniformly mixed at a mass ratio of 1:4. The mass concentration of the sodium hydroxide solution is 10%. The solid-liquid ratio of the nitrogen-doped montmorillonite to the sodium hydroxide solution is 1g:12.5mL.

[0074] Example 4:

[0075] A soil conditioner for degraded soil, the conditioner being composed of organic fertilizer and biochar, wherein the application rate of each component is: 15000 kg·hm² of organic fertilizer. -2 Biochar 6275.6 kg·hm -2 The remaining components, component contents, and preparation process are the same as in Example 1.

[0076] Example 5:

[0077] A soil conditioner for degraded soil, the conditioner being composed of organic fertilizer and biochar, wherein the application rate of each component is: 15000 kg·hm² of organic fertilizer. -2 Biochar 6275.6 kg·hm -2 The remaining components, component contents, and preparation process are the same as in Example 2.

[0078] Example 6:

[0079] A soil conditioner for degraded soil, the conditioner being composed of organic fertilizer and biochar, wherein the application rate of each component is: 15000 kg·hm² of organic fertilizer. -2 Biochar 6275.6 kg·hm -2 The remaining components, component contents, and preparation process are the same as in Example 3.

[0080] Results Analysis

[0081] The conditioners from Examples 3 and 6 were used in the experiment, with eight treatment groups: control (CK), organic fertilizer alone (F), woody peat alone (P), biochar alone (B), a combination of 1 / 2 organic fertilizer and 1 / 2 woody peat (1 / 2FP), a combination of 1 / 2 organic fertilizer and 1 / 2 biochar (1 / 2FB), a combination of 1 / 2 woody peat and 1 / 2 biochar (1 / 2PB), and a combination of 1 / 3 organic fertilizer, 1 / 3 woody peat, and 1 / 3 biochar (1 / 3FPB). The experiment employed a randomized block design with three replicates, resulting in 24 plots, each with an area of ​​57.12 m². 2 (8.4m × 6.8m). Except for CK, all organic materials in each treatment were treated with an equal carbon content (3075 kgC·hm). -2 ) Input. The application rates of each material, calculated by dry weight, are as follows: Organic fertilizer 15000 kg·hm² -2 Woody peat 5898.8 kg·hm -2Biochar 6275.6 kg·hm -2 The basic chemical properties of all materials are shown in Table 1. The field trial was conducted in May 2023. Before rice transplanting, the above-mentioned organic materials were applied as base fertilizer along with compound fertilizer [total nitrogen (N) 15%, available phosphorus (P2O5) 15%, potassium (K2O) 15%] at a rate of 600 kg·hm². -2 Fertilizer was thoroughly mixed with the soil by tilling (to a depth of 15cm), and no further topdressing was applied during the rice's growth period. The rice variety planted was Zhejingyou 1578, transplanted in early June 2023, and harvested in mid-November of the same year. Water management and pest and disease control during the trial period were implemented uniformly according to local high-yield models.

[0082] Table 1 Basic physicochemical properties of the test materials

[0083] materials pH <![CDATA[SOC g·kg -1 ]]> <![CDATA[TN g·kg -1 ]]> <![CDATA[TP g·kg -1 ]]> <![CDATA[AP mg·kg -1 ]]> C / N C / P N / P organic fertilizer 7.18 205.10 17.90 7.58 2779.88 11.46 27.06 2.36 woody peat 2.92 521.30 7.02 2.58 240.89 74.26 202.05 2.72 Biochar 9.61 490.00 6.07 1.63 135.83 80.72 300.61 3.72

[0084] The effects of different stable organic materials applied in this invention on soil chemical properties and stoichiometry, on rice yield, soil comprehensive fertility and cumulative mineralization, on soil enzyme activity, on soil microbial metabolism, on soil organic carbon functional groups, and on key physical indicators such as soil aggregate stability, porosity and bulk density are described in detail below. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 .

[0085] like Figure 1 As shown, in terms of soil chemical properties, application of biochar alone (B) and its combined application with organic fertilizer or woody peat (1 / 2FB, 1 / 2PB, 1 / 3FPB) significantly increased soil organic carbon (SOC) content. This indicates that inert organic materials play a prominent role in enhancing soil carbon sequestration. On the other hand, application of organic fertilizer alone (F) and its combined application with woody peat or biochar (1 / 2FP, 1 / 2FB) significantly increased the content of total nitrogen (TN), dissolved nitrogen (DN), and available phosphorus (AP) in the soil, demonstrating the advantages of active organic materials in rapidly supplying nutrients.

[0086] like Figure 2As shown, in terms of the synergy between crop yield and soil function, the combined application system (such as 1 / 2FP, 1 / 2FB) of reducing the amount of active organic materials (organic fertilizer) and supplementing with inert organic materials (woody peat or biochar) effectively overcomes the limitations of applying a single material. This system reduces the amount of active materials used and lowers the risk of carbon loss during their decomposition, while achieving long-term stability of the soil carbon pool through inert materials, and synergistically improves overall soil fertility, ultimately promoting a significant increase in rice yield.

[0087] like Figure 3 As shown, soil enzyme activity results indicate that, for key carbon cycle enzymes (such as cellobiose hydrolase CB), enzyme activity in single application treatments decreased significantly with decreasing material stability. However, compared to single application of organic fertilizer (F), the CB activities in treatments combining organic fertilizer with inert materials (1 / 2FP and 1 / 2FB) were significantly increased by 42.3% and 41.9%, respectively, indicating that combined application improved the carbon metabolism environment for microorganisms. Regarding nitrogen cycling, treatments containing only organic fertilizer (F, 1 / 2FP, and 1 / 2FB) significantly increased urease activity. The geometric mean (GMea) calculated based on multiple enzyme activities showed that the F and 1 / 2FP treatments were significantly higher than the control (CK). Combined application treatments, by improving nitrogen and phosphorus nutrient supply, prevent microorganisms from excessively "digging" for soil organic matter to obtain limiting nutrients, thus allowing them to use more carbon for their own growth and assimilation, reducing carbon loss through respiration, and promoting long-term carbon fixation.

[0088] like Figure 4 As shown, the analysis of soil microbial metabolic characteristics indicates that inert materials (woody peat and biochar), due to their high C / N and C / P ratios, exacerbate carbon and phosphorus limitation in microorganisms when applied alone. However, when combined with organic fertilizer, the active materials replenish sufficient nitrogen and available phosphorus, bringing the stoichiometric ratio of nutrients in the soil microbial community towards balance, alleviating nutrient limitation, promoting microbial growth and metabolic activity, and thus enhancing soil biofertility.

[0089] like Figure 5 As shown, analysis of soil organic carbon functional groups reveals that inert materials themselves contain a large amount of recalcitrant structural carbon (such as aromatic carbon and lignin carbon). The application system reduces the instantaneous supply of readily degradable organic carbon (DOC) in the soil. Figure 1 This reduced the availability of microbial respiratory substrates at the substrate level; simultaneously, it regulated the soil enzyme profile, manifested as a decrease in the ratio of oxidase to hydrolase activity. Figure 3 This inhibits the decomposition of stable carbon components. Together, these two factors ultimately lead to a reduction in CO2 emissions per unit of carbon input. Figure 2 This demonstrates the dual advantages of combined application in synergistically improving fertility and enhancing carbon sequestration.

[0090] like Figure 6 As shown, compared with the control (CK), all organic material application treatments improved soil physical structure to varying degrees. Among them, the application of biochar (B) and woody peat (P) alone significantly increased the content of water-stable aggregates >0.25 mm (R0.25) and mean weight diameter (MWD), mainly due to their stable porous structure and high carbon content, which act as "cementing cores" promoting soil particle aggregation. However, while the application of organic fertilizer (F) alone significantly reduced soil bulk density and increased total porosity, its effect on increasing water-stable large aggregates (R0.25) was limited, and its MWD value was relatively low, indicating that its active components contributed relatively weakly to the formation of stable aggregates during rapid decomposition. The combined application treatments (1 / 2FP and 1 / 2FB) at the core of this invention showed the best improvement effects in all structural indicators. Its R0.25 and MWD values ​​were significantly higher than all single application treatments and the 1 / 2PB and 1 / 3FPB treatments, indicating that the combined application of active organic materials (organic fertilizer) and inert organic materials (woody peat or biochar) produced a significant synergistic effect in promoting the formation of stable large aggregates. This is due to the active organic matter and microbial secretions provided by the organic fertilizer, which, combined with the stable porous framework provided by the woody peat / biochar, jointly constructed more robust soil aggregates. The 1 / 2FP and 1 / 2FB treatments simultaneously achieved the highest total porosity and the lowest soil bulk density, indicating that the conditioner of this invention can effectively reduce soil compaction, increase pore space, and create an excellent physical environment for water infiltration, air exchange, and root extension, directly verifying its volume expansion effect. The significant improvement in soil structure and the aforementioned improvement in soil nutrients ( Figure 1 ), enzyme activity optimization ( Figure 3 ) and microbial metabolic regulation ( Figure 4 This is closely related to the formation of microorganisms. A well-developed aggregate structure and porosity provide diverse microenvironments for microorganisms, protecting organic carbon and nutrients, thus jointly driving the synergistic restoration of overall soil fertility and ecological function.

[0091] 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.

[0092] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A degraded soil volume-expanding conditioner, characterized in that: The conditioner is composed of organic fertilizer and one of woody peat or biochar. The organic fertilizer is prepared through the following steps: S1 selects livestock and poultry manure and crop straw as raw materials, crushes the straw to 2-5cm, and then mixes it with livestock and poultry manure at a mass ratio of 1:2-1:3, adjusting the moisture content of the mixture to 55%-65%; S2. Add compound microbial agent to the mixture, stir evenly, and then pile it into a fermentation pile with a height of 1.0-1.5m and a width of 2.0-3.0m; S3. For the first 1-3 days, control the pile temperature at 30-40℃. On the 4th day, start turning the pile, and then turn it every 2 days thereafter, keeping the pile temperature at 55-65℃. Continue fermentation for 15 days, then add modified montmorillonite and mix evenly. The mass ratio of modified montmorillonite to the basic composted material is 0.03:1-0.05:

1. Continue fermentation for 5 days, then let it cool naturally to obtain the composted material. S4. Crush the decomposed material, pass it through an 80-mesh sieve to remove impurities, dry it in an 80-90℃ oven until the moisture content is ≤15%, crush it again and pass it through a 100-mesh sieve to obtain the finished organic fertilizer.

2. The degraded soil volume expander and conditioner according to claim 1, characterized in that: The modified montmorillonite is prepared through the following steps: montmorillonite is nitrogen-doped and alkalized to obtain alkalized montmorillonite; the alkalized montmorillonite is added to deionized water and ultrasonically dispersed to obtain a suspension; oleo-di(2-hydroxyethyl)methylammonium chloride is added to the suspension and reacted at 50-60℃ for 4-6 hours; then itaconic acid, acrylic acid, N,N-dimethylformamide, crosslinking agent and initiator are added to the system in sequence; the temperature is raised to 70-80℃ and stirred at a constant temperature for 6-8 hours; after the reaction is completed, the temperature is cooled to 40-50℃; tea saponin is added and stirred at a constant temperature for 1-2 hours; then the mixture is ultrasonically dispersed, filtered, washed, dried, pulverized and sieved to obtain the modified montmorillonite product.

3. The degraded soil volume expander and conditioner according to claim 2, characterized in that: The mass concentration of the alkalized montmorillonite suspension is 5%-8%, and the mass ratio of oil-based di(2-hydroxyethyl)methylammonium chloride to alkalized montmorillonite is 0.1:1-0.2:1; the mass ratio of itaconic acid to acrylic acid is 1:2-1:3; the mass ratio of the total mass of itaconic acid and acrylic acid to the mass of alkalized montmorillonite is 0.5:1-0.8:1; and the amount of N,N-dimethylformamide used is 5%-8% of the total mass of itaconic acid and acrylic acid.

4. The degraded soil volume expander and conditioner according to claim 3, characterized in that: The crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 1%-2% of the total mass of itaconic acid and acrylic acid; the initiator is selected from one of ammonium persulfate, potassium persulfate, and benzoyl peroxide, and the amount of the initiator is 0.5%-1% of the total mass of itaconic acid and acrylic acid; the mass ratio of tea saponin to alkalized montmorillonite is 0.05-0.1:

1.

5. The degraded soil volume expander and conditioner according to claim 4, characterized in that: The compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, and Bacillus mucilaginosa, and the total viable count of the compound microbial agent is not less than 1.0 × 10⁻⁶. 9 FU / g, wherein the amount of the compound microbial agent added is 0.1%-0.2% of the total mass of the mixture.

6. The degraded soil volume expander and conditioner according to claim 5, characterized in that: The nitrogen doping and alkalization treatment specifically includes: taking natural montmorillonite, drying it at 100-110℃ for 4-6 hours to remove free moisture, pulverizing it and passing it through a 200-mesh sieve to obtain refined montmorillonite powder, uniformly mixing the refined montmorillonite powder with urea, placing it in a tube furnace, and heating it to 500-600℃ at a heating rate of 5-8℃ / min under a nitrogen protective atmosphere, calcining it at a constant temperature for 2-3 hours, and then naturally cooling it to room temperature to obtain nitrogen-doped montmorillonite; adding the nitrogen-doped montmorillonite to a sodium hydroxide solution, stirring and reacting it at a solid-liquid ratio of 60-70℃ in a constant temperature water bath for 2-3 hours, cooling the system to room temperature after the reaction, washing it with deionized water until the pH of the washing solution is 7-8, filtering it, and then drying the filter cake in a 105℃ oven for 8-10 hours, pulverizing it and passing it through a 200-mesh sieve to obtain alkalized montmorillonite.

7. The degraded soil volume expander and conditioner according to claim 6, characterized in that: The refined montmorillonite and urea are uniformly mixed at a mass ratio of 1:3 to 1:

5. The mass concentration of the sodium hydroxide solution is 8% to 12%. The solid-liquid ratio of the nitrogen-doped montmorillonite to the sodium hydroxide solution is 1g:10-15mL.

8. The degraded soil volume expander and conditioner according to claim 7, characterized in that: The application rate of each component in the conditioner is: 15000 kg·hm² of organic fertilizer. -2 Woody peat 5898.8 kg·hm -2 Biochar 6275.6 kg·hm -2 .

9. A method for applying the degraded soil volume expander and conditioner according to claims 1-8, characterized in that: Before rice transplanting, the conditioner and compound fertilizer are applied together as base fertilizer. The fertilizer is then thoroughly mixed with the soil by tilling to a depth of 15cm. No additional fertilizer is applied during the rice growth period.

10. The method for applying the degraded soil volume expander and conditioner according to claim 9, characterized in that: The compound fertilizer contains 15% total nitrogen, 15% available phosphorus, and 15% potassium, and the application rate is 600 kg·hm². -2 .

Images