A soil conditioner, its preparation method and use

Abstract

The application relates to the technical field of soil improvement, and discloses a soil conditioner, a preparation method and application thereof. The soil conditioner is iron-based arboreal peat loaded with Bacillus mucilaginosus. The iron-based arboreal peat is combined with the Bacillus mucilaginosus, synergistic effects of organic-inorganic-biological are realized, the iron-based arboreal peat provides a stable habitat and nutrient substances for the Bacillus mucilaginosus, and the colonization rate and stress resistance of the strain in the soil are improved; the iron-based component contained in the iron-based arboreal peat can form a stronger cementing agent through complexation with polysaccharide, organic acid and other metabolites secreted by the Bacillus mucilaginosus, and the soil particle is significantly promoted to aggregate; meanwhile, the pore structure of the arboreal peat can improve soil aeration and water retention, and provide a good environment for microbial metabolism and aggregate formation; after being applied to the soil, the content of water-stable aggregates with a particle size greater than 0.25 mm in the soil can be increased by 20%-40%, and the average weight diameter of the aggregates can be increased by 25%-40%.

Description

Technical Field

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

[0002] Soil aggregates, as the basic units of soil structure, directly affect soil aeration, water retention, fertility retention, and erosion resistance in terms of quantity and stability. However, globally, due to long-term irrational agricultural practices, excessive application of chemical fertilizers, and natural degradation, soil aggregates are generally showing a trend of decreasing quantity and declining stability. This leads to a series of problems such as soil compaction, nutrient loss, and reduced crop yields, seriously hindering sustainable agricultural development and the improvement of ecological environment quality.

[0003] To address these issues, various soil conditioners have been developed, primarily categorized into four types: chemical conditioners, mineral conditioners, biological conditioners, and compound conditioners. Chemical conditioners, such as polyacrylamide and gypsum, can rapidly improve soil structure in the short term, but they are costly, and long-term use can easily cause secondary soil pollution and potentially disrupt the balance of soil microbial communities. Mineral conditioners, such as montmorillonite and vermiculite, are widely available and inexpensive, but their effectiveness when used alone is limited, and their promotion of soil microbial activity is weak. Biological conditioners, such as beneficial microbial agents, can improve soil physicochemical properties and promote aggregate formation through microbial metabolic activities, but their colonization ability in the soil is often weak, and they are easily deactivated by environmental factors such as drought and heavy metal pollution, making it difficult to sustain the improvement effect.

[0004] Woody peat, as a natural organic matrix, possesses abundant carboxyl functional groups, high organic matter content, strong adsorption capacity, and electron shuttle ability. It not only provides a favorable habitat and nutrients for microorganisms but also promotes electron transfer of iron in the soil, accelerating its redox process and influencing the morphology of soil minerals and organic matter. Therefore, it has been applied to some extent in soil improvement. However, single woody peat has insufficient structural stability and limited cementing effect on soil aggregates. Iron-based materials (such as nano-zero-valent iron and iron oxide) have strong chemical activity and cementing ability, promoting soil particle aggregation through complexation. However, single iron-based materials are prone to oxidative aggregation, have poor dispersibility in soil, and lack regulatory effects on microbial activity. Bacillus mucilaginosus (…) Bacillus mucilaginosus (This is a type of beneficial microorganism widely found in soil. It can secrete sticky metabolites such as polysaccharides and organic acids. These products can act as cementing agents to promote the aggregation of soil particles. At the same time, its metabolic activities can also activate soil nutrients. However, the colonization rate of this strain in adverse soil conditions is low, making it difficult to sustain its effects.) 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 conditioner.

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

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

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a soil conditioner, said soil conditioner being iron-based woody peat loaded with Bacillus subtilis.

[0009] In some embodiments of the present invention, the soil conditioner comprises the following raw materials: iron source, woody peat, Bacillus subtilis, slow-release carrier, reducing agent, binder and water.

[0010] In some embodiments of the present invention, the particle size of the soil conditioner is ≤80 mesh.

[0011] In some preferred embodiments of the present invention, the particle size of the soil conditioner is 80-100 mesh.

[0012] In some embodiments of the present invention, the particle size of the woody peat is ≤80 mesh.

[0013] In some preferred embodiments of the present invention, the particle size of the woody peat is 80-100 mesh.

[0014] In some embodiments of the present invention, the woody peat is prepared by a method comprising the following steps: drying natural woody peat at 60-70°C or air-drying it, then pulverizing it and sieving it to obtain the woody peat.

[0015] Specifically, In some embodiments of the present invention, the particle size of the sustained-release carrier is ≤100 mesh.

[0016] In some preferred embodiments of the present invention, the particle size of the sustained-release carrier is 100-200 mesh.

[0017] In some embodiments of the present invention, the iron source is selected from at least one of water-soluble iron salts and water-soluble ferrous salts.

[0018] In some preferred embodiments of the present invention, the water-soluble iron salt includes at least one of ferric sulfate, ferric chloride, and ferric nitrate.

[0019] In some preferred embodiments of the present invention, the water-soluble ferrous salt includes at least one of ferrous sulfate, ferrous chloride, ferrous perchlorate, and ferrous ammonium sulfate.

[0020] In some embodiments of the present invention, the slow-release carrier is selected from at least one of dolomite powder, diatomite, and zeolite powder.

[0021] In some embodiments of the present invention, the reducing agent is selected from at least one of sodium borohydride, ascorbic acid, and hydrazine hydrate (N2H4·H2O).

[0022] In some embodiments of the present invention, the binder is selected from at least one of sodium carboxymethyl cellulose, starch, and sodium alginate.

[0023] A second aspect of the present invention provides a method for preparing the soil conditioner described in the first aspect of the present invention, comprising the following steps: S1. Iron source is dissolved in water to form an iron-based precursor solution, which is then mixed with woody peat for a first-stage reaction. A reducing agent is added for a second-stage reaction to obtain iron-based woody peat. S2. The iron-based woody peat is mixed with a slow-release carrier and co-cultured with Bacillus mucilaginosus inoculum. A binder is added to obtain a mixed slurry, which is then dried and crushed to obtain the soil conditioner.

[0024] In some embodiments of the present invention, in step S1, the concentration of the iron-based precursor solution is 0.1-0.5 mol / L; the liquid-to-solid ratio of the iron-based precursor solution to the woody peat is (5-10) mL: 1 g.

[0025] In some preferred embodiments of the present invention, in step S1, the concentration of the iron-based precursor solution is 0.2-0.4 mol / L; the liquid-solid ratio of the iron-based precursor solution to the woody peat is (5-8) mL: 1 g.

[0026] In some embodiments of the present invention, in step S1, the molar ratio of the reducing agent to the iron source is (1-5):1.

[0027] In some preferred embodiments of the present invention, in step S1, the molar ratio of the reducing agent to the iron source is (1-3):1.

[0028] In some embodiments of the present invention, in step S1, the temperature of the first stage of reaction is 30-45°C and the time is 2-5 hours.

[0029] In some preferred embodiments of the present invention, in step S1, the temperature of the first stage of reaction is 33-40°C and the time is 2-4 hours.

[0030] In some embodiments of the present invention, in step S1, the time for the two-stage reaction is 1-3 hours.

[0031] In some preferred embodiments of the present invention, in step S1, the time for the two-stage reaction is 1-2 hours.

[0032] In some embodiments of the present invention, in step S1, both the first-stage reaction and the second-stage reaction are assisted by stirring, and the stirring speed is selected from 150-200 r / min.

[0033] In some embodiments of the present invention, after the two-stage reaction is completed in step S1, the solid phase is further subjected to solid-liquid separation, collection, washing to neutrality, vacuum drying, and crushing.

[0034] In some embodiments of the present invention, the washing agent includes water.

[0035] In some embodiments of the present invention, the drying temperature is 60-80°C.

[0036] Specifically, the preparation of iron-based woody peat is carried out in two stages. The first stage involves moderately raising the temperature to increase the diffusion rate and reactivity of iron ions, while continuous stirring ensures uniform concentration and temperature to prevent local precipitation. The reaction time is sufficient to allow iron ions to fully diffuse into the micropores inside the peat. The second stage reaction, after the addition of a reducing agent, removes the adsorbed Fe... 3+ / Fe 2+ Reduce to nano-zero valent iron or active low valent iron oxide, and continue stirring for 1-3 hours to ensure the full progress of the reduction reaction.

[0037] In some embodiments of the present invention, in step S2, the mass ratio of the iron-based woody peat to the slow-release carrier is (5-10):1.

[0038] In some preferred embodiments of the present invention, in step S2, the mass ratio of the iron-based woody peat to the slow-release carrier is (5-8):1.

[0039] In some embodiments of the present invention, step S2, after the iron-based woody peat is mixed with the slow-release carrier, further includes a high-temperature sterilization operation.

[0040] In some embodiments of the present invention, in step S2, the viable count of the Bacillus mucilaginosus bacterial solution is 1×10⁻⁶. 9 -2×10 9 The solid-liquid ratio of the iron-based woody peat to the Bacillus mucilaginosus bacterial solution is 1 g: (2-5) mL.

[0041] In some preferred embodiments of the present invention, in step S2, the viable count of the Bacillus mucilaginosus bacterial solution is 1×10⁻⁶.9 -1.5×10 9 The solid-liquid ratio of the iron-based woody peat to the Bacillus mucilaginosus bacterial solution is 1 g: (2-4) mL.

[0042] In some embodiments of the present invention, in step S2, the bacterial culture of Bacillus mucilaginosus is prepared by a method comprising the following steps: inoculating the Bacillus mucilaginosus strain into a modified LB medium and culturing it in a shake flask at 30-37°C and 180-220 r / min for 24-48 h to obtain a bacterial culture of Bacillus mucilaginosus in the logarithmic growth phase.

[0043] In some embodiments of the present invention, the components of the modified LB medium include: 8-12 g / L peptone, 4-6 g / L yeast extract, 4-6 g / L sodium chloride, 16-24 g / L glucose, 0.8-1.2 g / L potassium dihydrogen phosphate, and 0.4-0.6 g / L magnesium sulfate.

[0044] In some embodiments of the present invention, the pH of the modified LB medium is 7.0-7.2.

[0045] In some embodiments of the present invention, the modified LB medium is autoclaved at 121°C for 20 min.

[0046] In some embodiments of the present invention, in step S2, the co-cultivation temperature is 20-30°C and the time is 4-6 hours.

[0047] In some preferred embodiments of the present invention, in step S2, the co-cultivation temperature is 25-30°C and the time is 5-6 hours.

[0048] In some embodiments of the present invention, in step S2, the co-cultivation process is supplemented by stirring, with a stirring speed of 100-150 r / min.

[0049] In some embodiments of the present invention, in step S2, the amount of the binder is 1%-5% of the mass of the iron-based woody peat.

[0050] In some preferred embodiments of the present invention, in step S2, the amount of the binder is 2%-4% of the mass of the iron-based woody peat.

[0051] In some embodiments of the present invention, in step S2, after adding the binder, the mixture is stirred at a speed of 100-150 r / min for 1-2 hours to obtain the mixed slurry.

[0052] In some embodiments of the present invention, in step S2, the drying is vacuum drying at a temperature of 40-50°C until the moisture content of the mixed slurry is ≤15%.

[0053] The third aspect of the present invention provides the application of the soil conditioner described in the first aspect of the present invention in soil improvement.

[0054] In some embodiments of the present invention, the soil improvement includes at least one of the following: a. Increase the content of water-stable aggregates with a particle size greater than 2.5 mm in the soil; b. Increase the organic matter content in the soil; c. Increase soil porosity; d. Reduce soil bulk density.

[0055] In some embodiments of the present invention, the soil includes dryland clay soil and clay paddy field soil.

[0056] In some embodiments of the present invention, the amount of the soil conditioner used is 100-300 kg / mu.

[0057] In some preferred embodiments of the present invention, the amount of the soil conditioner used is 150-250 kg / mu.

[0058] In some embodiments of the present invention, the method of applying the soil conditioner includes: spreading the soil conditioner on the soil surface, tilling the soil to mix the soil conditioner with the soil to a depth of 0-20 cm, and maintaining the soil moisture content at 60%-80% of field capacity.

[0059] In some embodiments of the present invention, when the soil conditioner is applied to improve the soil of dryland clay soil, the method of application includes: applying the soil conditioner during the tillage period.

[0060] In some embodiments of the present invention, when the soil conditioner is applied to improve the soil of sticky paddy fields, the method of application includes: spreading the soil conditioner during the plowing and harrowing period, or applying the soil conditioner together with straw return measures after the late rice harvest.

[0061] The basic principles of this invention are explained as follows: This invention (1) uses woody peat as a porous carrier, which has a rich fibrous and porous structure. After being applied to the soil, it can directly separate soil particles, increase large pores, break up compaction, and protect microorganisms from stresses such as drought and high temperature. At the same time, woody peat is also rich in organic matter such as humic acid and fulvic acid, which are high-quality carbon and energy sources for soil microorganisms and can continuously stimulate the proliferation and metabolism of beneficial bacteria such as Bacillus mucilaginosus. (2) Iron salt (after reduction) provides key cementing force. Under the action of the reducing agent, the iron salt generates nano-zero valent iron or nano-zero ferrous iron on the surface and in the pores of the peat. Amorphous iron oxides have extremely high specific surface area and reactivity; their surface Fe-OH groups can combine with the -OH groups on the surface of soil clay minerals (such as silicates) through hydrogen bonds and coordination bonds; they can also complex or bridge with the functional groups such as -COOH and -OH in the polysaccharides and humic acids secreted by peat and bacteria, forming an "organic-iron-mineral" ternary composite cement bridge; compared with traditional cementing agents such as lime and gypsum, the cement network formed by active iron has better toughness and water erosion resistance, and is more conducive to increasing the content of water-stable aggregates in the soil; (3) During its growth, Bacillus mucilaginosus secretes a large amount of extracellular polysaccharides and organic acids. These high-molecular-weight polysaccharides are like "natural biological glue" that can bind soil particles together. The organic acids produced by its metabolism can also dissolve insoluble minerals such as phosphorus and potassium in the soil, release nutrients, and produce CO2 and hormones through metabolic activities, stimulating plant root growth and microbial community prosperity. The functional groups on the polysaccharide chains it secretes can specifically complex with the active iron ions loaded in front to form a "polysaccharide-iron" composite binder. The stability and adaptability of this biological-inorganic hybrid binder are far higher than those of a single component. (4) The slow-release carrier is a porous mineral that can adsorb and slowly release nutrients and water, creating a mild microenvironment for the agent in the soil and prolonging its effective action time. (5) The binder can fix various components together during the drying and granulation process, preventing pulverization during storage and ensuring good dispersibility of the product when it is applied.

[0062] In the preparation process, highly active iron is first anchored onto the three-dimensional network of peat through impregnation-reduction to form a primary reinforcing structure, resulting in iron-based woody peat. Then, through adsorption-fixation, Bacillus mucilaginosus is loaded onto the interior and surface of the iron-based woody peat to construct a bioactive coating. The final product is a composite particle integrating peat organic matter, active iron, and Bacillus mucilaginosus. When this particle is mixed with soil particles, it can directly increase structural sites. The active iron undergoes a cementing reaction with various particles in the soil to form stable chemical bonds. After colonization, Bacillus mucilaginosus continuously secretes polysaccharides and promotes the evolution of the entire soil microbial community in a beneficial direction, forming a continuous biocementation and pore-forming ability. The organic-iron complex cementing network formed by the polysaccharides secreted by the bacteria and the active iron on the carrier reaches its peak strength and water stability, resulting in a significant increase in soil water-stable aggregates.

[0063] Compared with the prior art, the beneficial effects of the present invention are: 1) The soil conditioner provided by this invention combines iron-based woody peat with Bacillus mucilaginosus, achieving a synergistic effect of organic-inorganic-biological processes. Iron-based woody peat not only provides a stable habitat and nutrients for Bacillus mucilaginosus, improving the colonization rate and stress resistance of the strain in the soil, but its iron-based components can also complex with the polysaccharides, organic acids, and other metabolites secreted by Bacillus mucilaginosus, forming a stronger cementing agent and significantly promoting soil particle aggregation. At the same time, the porous structure of woody peat can improve soil aeration and water retention, providing a good environment for microbial metabolism and aggregate formation. Compared with single conditioners, it can improve the soil aggregate structure from both physical cementation and microbial metabolic regulation aspects, increasing the content of water-stable aggregates with a particle size greater than 0.25 mm in the soil by 20%-40% and the average weight diameter of aggregates by 25%-40%. Moreover, the improvement effect can last for 1-2 planting seasons, effectively solving the problem of short-term effects of existing conditioners. 2) The soil conditioner provided by this invention uses natural and renewable resources as raw materials, which are widely available and low in cost; the preparation method is simple to operate, does not require harsh conditions such as high temperature and high pressure, has low energy consumption, and does not produce harmful waste. The required equipment is conventional chemical and microbial culture equipment, which does not require special customization and is easy to achieve large-scale production and promotion. 3) The soil conditioner provided by this invention will not cause secondary pollution to the soil after being applied to soil improvement. It can also increase the soil organic matter content and microbial activity, which meets the requirements of sustainable agricultural development. It has good application effects on dryland clay soil and clay paddy field soil, and has strong applicability. Attached Figure Description

[0064] Figure 1 Photograph of the dried powder of Bacillus mucilaginosus used in Example 1; Figure 2 This is a scanning electron microscope image of the soil conditioner prepared in Example 1; Figure 3 Soil particle size distribution diagrams for each treatment group in Experiment Example 1; Figure 4 The average weight diameter of soil aggregates in each treatment group in Experiment Example 1; Figure 5 The soil bulk density of each treatment group in Experiment Example 1; Figure 6 The soil porosity of each treatment group in Experiment Example 1; Figure 7 The rice yield of each treatment group in Experiment Example 2; Figure 8The yield of fresh corn ears in each treatment group in Experiment Example 3 is given. Detailed Implementation

[0065] 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 can be obtained from conventional commercial sources or by existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0066] Note: The Bacillus mucilaginosus used in the following examples and test cases... Bacillus mucilaginosus Purchased from the China General Microbiological Culture Collection Center, accession number CGMCC No.1.15986; The culture medium used for the expansion culture of Bacillus mucilaginosus was a modified LB medium with the following formula: 10 g / L peptone, 5 g / L yeast extract, 5 g / L sodium chloride, 20 g / L glucose, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate, pH=7.0, and autoclaved at 121℃ for 20 min.

[0067] Example 1 This embodiment prepares a soil conditioner using the following steps: S11. Dissolve ferric chloride in water to obtain a ferric chloride solution with a concentration of 0.3 mol / L; select natural woody peat from Indonesia, air dry it naturally, then pulverize it with a pulverizer and pass it through an 80-mesh sieve to obtain woody peat powder. S12. Weigh 100g of woody peat powder and add it to 500mL of ferric chloride solution. Stir the mixture at 35℃ and 180r / min for 3h. Then add 10g of sodium borohydride (molar ratio of 2:1 to ferric chloride) and continue stirring for 1.5h. S13. After the reaction is complete, centrifuge at 5000 r / min for 10 min, collect the precipitate, wash with deionized water until pH=7.0, vacuum dry at 70℃ to constant weight, pulverize and pass through a 100 mesh sieve to obtain iron-based woody peat. S21. The *Bacillus mucilaginosus* strain was inoculated into modified LB medium and cultured in shake flasks at 35℃ and 200 rpm for 36 h to obtain a *Bacillus mucilaginosus* suspension in the logarithmic growth phase. The viable count was determined by plate counting to be 1.5 × 10⁻⁶. 9 CFU / mL; S22. Weigh 80g of iron-based woody peat, mix it evenly with 10g of diatomaceous earth (100 mesh), sterilize it at high temperature, and add it to 240mL of Bacillus mucilaginosus bacterial solution. Stir and adsorb at a constant temperature of 28℃ and 120 r / min for 5h. Then add 2.4g of sodium carboxymethyl cellulose and continue stirring for 1.5h to obtain a mixed slurry. Vacuum dry the mixed slurry at 45℃ until the moisture content is 12%, pulverize it and pass it through an 80-mesh sieve to obtain a soil conditioner.

[0068] Figure 1 This is a photograph of the dried powder of Bacillus mucilaginosus used in Example 1. Figure 2 This is a scanning electron microscope image of the soil conditioner prepared in Example 1. Figure 2 It can be seen that the Bacillus mucilaginosus cells are attached to the rich pore structure and fiber surface of the iron-based woody peat, indicating that this embodiment has achieved the immobilization of microorganisms on the carrier and successfully prepared iron-based woody peat loaded with Bacillus mucilaginosus.

[0069] Example 2 This embodiment prepares a soil conditioner using the following steps: S11. Dissolve ferrous sulfate in water to obtain a ferrous sulfate solution with a concentration of 0.4 mol / L; select natural woody peat from Indonesia, dry it at 65℃, pulverize it with a pulverizer, and pass it through an 80-mesh sieve to obtain woody peat powder. S12. Weigh 100g of woody peat powder and add it to 700mL of ferrous sulfate solution. Stir the mixture at 35℃ and 180r / min for 3h. Then add 42g of hydrazine hydrate (molar ratio of 3:1 to ferrous sulfate) and continue stirring for 1.5h. S13. After the reaction is complete, centrifuge at 5000 r / min for 10 min, collect the precipitate, wash with deionized water until pH=7.0, vacuum dry at 70℃ to constant weight, pulverize and pass through a 100 mesh sieve to obtain iron-based woody peat. S21. The *Bacillus mucilaginosus* strain was inoculated into modified LB medium and cultured in shake flasks at 35℃ and 200 rpm for 36 h to obtain a *Bacillus mucilaginosus* suspension in the logarithmic growth phase. The viable count was determined by plate counting to be 1.2 × 10⁻⁶. 9 CFU / mL; S22. Weigh 50g of iron-based woody peat, mix it evenly with 10g of zeolite powder (100 mesh), sterilize it at high temperature, and add it to 200mL of Bacillus mucilaginosus bacterial solution. Stir and adsorb at a constant temperature of 28℃ and 120 r / min for 5h. Then add 1.5g of sodium alginate and continue stirring for 1.5h to obtain a mixed slurry. Vacuum dry the mixed slurry at 45℃ until the moisture content is 12%, pulverize it and pass it through an 80-mesh sieve to obtain a soil conditioner.

[0070] Experimental Example 1 This experiment verifies the effectiveness of the soil conditioner prepared in Example 1 in improving the soil of sticky paddy fields through a pot experiment. The method is as follows: The experimental soil was taken from typical clay loam paddy fields in South China. The soil texture was clay loam, the content of water-stable aggregates with a particle size greater than 2.5 mm was 39.4%, the average weight diameter (MWD) of the aggregates was 0.82 mm, the organic matter content was 28.3 g / kg, and the soil pH was 5.20. A plastic box test was conducted, with 35 kg of undisturbed soil (without crushing) added to each plastic box.

[0071] The experiment was set up with 4 treatment groups, each with 3 replicates: Treatment group 1: No modifier was applied, serving as the control group, denoted as CK; Treatment group 2: Apply the iron-based woody peat obtained in step S13 of Example 1 at a rate of 24g / box, denoted as WP; Treatment group 3: 1.2 × 10⁻⁶ viable bacteria were applied. 9 CFU / mL Bacillus mucilaginosus bacterial solution, used at a volume of 45mL / box, is designated as B; Treatment group 4: The soil conditioner prepared in Example 1 was applied at a dosage of 30g / box, denoted as WPB.

[0072] During the experiment, the water and nutrient management of each group was consistent. Each amendment was applied to the topsoil before rice transplanting and mixed thoroughly to a depth of 10 cm. One season of rice was planted. After the rice was harvested at maturity, the soil was allowed to dry naturally. Aggregate and bulk density information were collected in situ, and the rhizosphere soil of the rice was collected to test the soil physicochemical properties.

[0073] Figure 3 This is a soil particle size distribution diagram for each treatment group in Experiment Example 1. Figure 4 The mean weight diameter of soil aggregates in each treatment group in Example 1 is given, where different lowercase letters represent significant differences. p <0.05), Figure 5 The soil bulk density represents the weight of each treatment group in Experiment 1, where different lowercase letters indicate significant differences. p <0.05), Figure 6 The soil porosity of each treatment group in Experiment Example 1 is determined by... Figures 3-6It was found that in all four treatment groups, the soil water-stable aggregates were mainly micro-aggregates with a particle size of less than 0.25 mm. Compared with the control group (CK), the content of micro-aggregates with a particle size of less than 0.25 mm in the soil of the WP, B and WPB treatment groups decreased by 11.55%, 12.05% and 23.76% respectively, and the average weight diameter of the aggregates increased significantly. The soil bulk density and soil porosity of the WP and WPB treatment groups decreased significantly. Among them, the WPB treatment group was significantly better than the other groups. Compared with the CK group, the average weight diameter of the aggregates in the soil increased significantly by 35.3%, the bulk density decreased by 17.2% and the porosity increased by 20.1%. This shows that the soil conditioner prepared in Example 1 promoted the transformation of soil micro-aggregates into large aggregates, reduced the aggregate destruction rate, improved the stability of soil structure, and had a better effect than Bacillus mucilaginosus liquid and iron-based woody peat.

[0074] Experimental Example 2 This experimental example verifies the application effect of the soil conditioner prepared in Example 1 in soil improvement of sticky paddy fields through field trials. The method is as follows: The experiment was conducted in a clay loam paddy field in Nanxiong City, Shaoguan City, Guangdong Province. The soil texture was clay loam, the content of water-stable aggregates with a particle size greater than 2.5 mm was 18.6%, the average weight diameter (MWD) of the aggregates was 0.56 mm, the organic matter content was 12.3 g / kg, and the soil pH was 5.06. A field plot experiment was conducted, with each plot covering an area of ​​30 m². 2 .

[0075] The experiment was set up with 4 treatment groups, each with 3 replicates: Treatment group 1: No modifier was applied, serving as the control group, denoted as CK; Treatment Group 2: Apply the iron-based woody peat obtained in step S13 of Example 1 at a rate of 200 kg / mu, denoted as WP; Treatment group 3: The soil conditioner prepared in Example 1 was applied at a rate of 200 kg / mu, denoted as WPB; Treatment group 4: 1.2 × 10⁻⁶ viable bacteria were applied. 9 The amount of Bacillus mucilaginosus culture with a concentration of CFU / mL was the same as that in treatment group 3, and was designated as B.

[0076] During the experiment, the water and nutrient management of each group was consistent. The experimental cycle was two rice seasons a year. The soil conditioner was applied one week before rice transplanting and the field was plowed and harrowed. After the late rice was harvested and the field was dried, soil samples of 0-20 cm were collected to determine the soil aggregates, organic matter content and bulk density. The yield of rice was determined by using a yield measurement circle at the maturity period of the late rice.

[0077] Table 1. Soil bulk density, organic matter content, water-stable aggregate content, and average weight diameter of aggregates in Experiment Example 2.

[0078] Table 1 shows the soil bulk density, organic matter content, water-stable aggregate content, and average weight diameter of aggregates in Experiment Example 2. As shown in Table 1, in the WPB treatment group, the content of micro-aggregates with a particle size greater than 0.25 mm, the average weight diameter of aggregates, and the soil organic matter content increased by 57.1%, 41.1%, and 19.5% respectively compared with the control group (CK), and by 21.7%, 25.4%, and 10.9% respectively compared with the WP treatment group. The soil bulk density decreased by 10.6% and 4.6% compared with the CK and WP treatment groups, respectively. Figure 7 The figures represent the rice yield of each treatment group in Experiment Example 2, where different lowercase letters indicate significant differences. p <0.05), by Figure 7 It can be seen that the rice yield in the WPB treatment group increased by 11.4% and 6.6% compared with the CK and WP treatment groups, respectively. This indicates that the soil conditioner prepared in Example 1 has a significantly better effect on improving the soil aggregate structure than iron-based woody peat and the control group. It can effectively improve the soil structure, transforming it from compacted to loose and stable, and effectively promote rice yield.

[0079] Experimental Example 3 This experimental example verifies the application effect of the soil conditioner prepared in Example 1 in soil improvement of dryland with sticky boards through field trials. The method is as follows: The experiment was conducted in a dryland clay loam soil in Nansha District, Guangzhou City, Guangdong Province. The soil texture was sandy loam, and the content of water-stable aggregates with a particle size greater than 2.5 mm was 12.5%, the average weight diameter (MWD) of the aggregates was 0.39 mm, and the organic matter content was 8.2 g / kg. A field plot experiment was conducted, with each plot covering an area of ​​15 m². 2 .

[0080] The experiment was set up with 4 treatment groups, each with 3 replicates: Treatment group 1: No modifier was applied, serving as the control group, denoted as CK; Treatment Group 2: Apply the iron-based woody peat obtained in step S13 of Example 1 at a rate of 300 kg / mu, denoted as WP; Treatment group 3: The soil conditioner prepared in Example 1 was applied at a rate of 300 kg / mu, denoted as WPB; Treatment group 4: 1.2 × 10⁻⁶ viable bacteria were applied. 9 The amount of Bacillus mucilaginosus culture with a concentration of CFU / mL was the same as that in treatment group 3, and was designated as B.

[0081] During the experiment, water and nutrient management were consistent across all groups. The experiment lasted 12 months, with spring and autumn maize planted. The maize variety was Guangtian No. 3. The soil conditioner was applied to the soil surface during tillage, and tillage was performed to ensure thorough mixing of the conditioner with the soil to a depth of 15 cm. After the experiment, soil samples from 0-20 cm were collected to determine soil aggregates, organic matter content, and bulk density. At maize maturity, the yield of fresh ears was measured using yield measurement circles.

[0082] Table 2. Soil bulk density, organic matter content, water-stable aggregate content, and average weight diameter of aggregates in Experiment Example 3.

[0083] Table 2 shows the soil bulk density, organic matter content, water-stable aggregate content, and average weight diameter of aggregates in Experiment Example 3. Figure 8 The yield of fresh maize ears in each treatment group in Experiment 3 is given, where different lowercase letters represent significant differences. p <0.05), from Table 2 and Figure 8 It can be seen that, compared with the B and WPB treatment groups, the WPB treatment group more effectively increased the content of water-stable aggregates with a particle size greater than 0.25 mm, the average weight diameter of aggregates, and the soil organic matter content, while reducing soil bulk density. It effectively improved the aggregate structure of dryland clay soil, reduced the degree of soil compaction, improved soil aeration, water retention and root extension space, and increased water and nutrient use efficiency, thereby increasing the yield of fresh maize ears.

[0084] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A soil conditioner, characterized in that, The soil conditioner is iron-based woody peat loaded with Bacillus subtilis.

2. The soil conditioner according to claim 1, characterized in that, The soil conditioner comprises the following raw materials: iron source, woody peat, Bacillus subtilis, slow-release carrier, reducing agent, binder and water.

3. The soil conditioner according to claim 2, characterized in that, The particle size of the soil conditioner is ≤80 mesh; And / or, the particle size of the woody peat is ≤80 mesh; And / or, the particle size of the sustained-release carrier is ≤100 mesh.

4. The soil conditioner according to claim 3, characterized in that, The iron source is selected from at least one of water-soluble iron salts and water-soluble ferrous salts; And / or, the slow-release carrier is selected from at least one of dolomite powder, diatomite, and zeolite powder; And / or, the reducing agent is selected from at least one of sodium borohydride, ascorbic acid, and hydrazine hydrate; And / or, the binder is selected from at least one of sodium carboxymethyl cellulose, starch, and sodium alginate.

5. The method for preparing the soil conditioner according to any one of claims 2-4, characterized in that, Includes the following steps: S1. Iron source is dissolved in water to form an iron-based precursor solution, which is then mixed with woody peat for a first-stage reaction. A reducing agent is added for a second-stage reaction to obtain iron-based woody peat. S2. The iron-based woody peat is mixed with a slow-release carrier and co-cultured with Bacillus mucilaginosus inoculum. A binder is added to obtain a mixed slurry, which is then dried and crushed to obtain the soil conditioner.

6. The preparation method according to claim 5, characterized in that, In step S1, the concentration of the iron-based precursor solution is 0.1-0.5 mol / L; the liquid-solid ratio of the iron-based precursor solution to the woody peat is (5-10) mL: 1 g. And / or, the molar ratio of the reducing agent to the iron source is (1-5):1; And / or, the temperature of the first stage of the reaction is 30-45℃, and the time is 2-5h; And / or, the time for the two-stage reaction is 1-3 hours.

7. The preparation method according to claim 5, characterized in that, In step S2, the mass ratio of the iron-based woody peat to the slow-release carrier is (5-10):1; And / or, the viable count of the Bacillus mucilaginosus bacterial solution is 1×10⁻⁶. 9 -2×10 9 CFU / mL, the solid-liquid ratio of the iron-based woody peat to the Bacillus mucilaginosus bacterial solution is 1g: (2-5)mL; And / or, the co-culture temperature is 20-30℃, and the time is 4-6h; And / or, the amount of the binder is 1%-5% of the mass of the iron-based woody peat.

8. The application of the soil conditioner according to any one of claims 1-4 in soil improvement.

9. The application according to claim 8, characterized in that, The soil improvement includes at least one of the following: a. Increase the content of water-stable aggregates with a particle size greater than 2.5 mm in the soil; b. Increase the organic matter content in the soil; c. Increase soil porosity; d. Reduce soil bulk density.

10. The application according to claim 8, characterized in that, The dosage of the soil conditioner is 100-300 kg / mu.

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