Application of an improved agent in improving physical structure of sand ginger black soil

Abstract

The application discloses application of an improved agent in improving physical structure of sand ginger black soil, and the improved agent adopts coal gangue alkali modified material. Before planting crops in the sand ginger black soil, the coal gangue alkali modified material is applied, and the land is directly rotary ploughed, and the alkali modified coal gangue can be brought into the deep layer during rotary ploughing, so that the pore structure of the sand ginger black soil is better improved. The coal gangue produced in the process of coal mining and washing is rich in organic matter and has a loose porous structure, but the specific surface area of the natural coal gangue is small, and the hardness is high. The alkali modification process can effectively loosen the structure of the coal gangue, reduce the strength of minerals such as quartz, increase the pore number and total pore volume of the coal gangue, and the coal gangue added into the sand ginger black soil can further enhance the water holding property and air permeability of the soil, improve the organic matter content of the soil, and improve the water and fertilizer retaining performance of the soil.

Description

Technical Field

[0001] This invention relates to the field of coal-based solid waste material recycling, and in particular to the application of a modifier in improving the physical structure of sandy black soil. Background Technology

[0002] Sandy black soil is a typical medium-to-low-yield soil type in my country, usually located in low-lying areas, covering an area of ​​approximately 4 million hectares. 2 Its characteristics include black soil color, low organic matter content, weak alkalinity, high bulk density, heavy texture, short suitable cultivation period, and obvious swelling and shrinking characteristics, which seriously affect the soil's physical properties. The topsoil of sandy loam black soil is fertile and suitable for planting high-yield crops, such as wheat, corn, soybeans, and cotton. However, the presence of the sandy loam layer hinders soil moisture penetration, affects crop root growth, leads to soil compaction, and results in poor drought resistance.

[0003] The area where the sandy black soil is located has flat terrain, good water and heat conditions, and concentrated and large arable land, which has great potential for comprehensive utilization. Reasonable and effective measures are the key to improving the physical and chemical properties of the soil. After the coal gangue is modified, its minerals such as silicon, aluminum and iron can be released after activation, providing nutrients to the soil. In addition, it can improve the physical structure of the soil, enhance the soil's water and fertilizer retention capacity, and promote the activity and growth of soil microorganisms, thereby promoting the sequestration and transformation of organic carbon, providing nutrients, and having great potential for increasing yield.

[0004] However, the existing sandy black soil improvement methods have the following drawbacks:

[0005] (1) Soil pH issue: Sandy black soil sometimes tends to be acidic, which is detrimental to the growth of certain crops. Improvement can ensure a suitable pH level.

[0006] (2) Unstable soil structure: The soil particles of sandy black soil are relatively loose and well-aerated, but the water retention capacity is poor. When applying organic fertilizer or irrigating, it is easy to have too much or too little water, which leads to unstable crop growth;

[0007] (3) Nutrient loss is relatively fast: Because the soil particles are relatively loose, nutrients are easily carried away by water flow, resulting in soil infertility and the effect of fertilization is not lasting.

[0008] Therefore, there is an urgent need to provide a new type of modifier to improve the physical structure of sandy black soil. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide an application of a soil conditioner in improving the physical structure of sandy black soil, which can effectively improve the soil structure of sandy black soil.

[0010] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide an application of a modifier in improving the physical structure of sandy black soil, wherein the modifier is a coal gangue alkali-modified material.

[0011] In a preferred embodiment of the present invention, before planting crops on sandy loam black soil, an alkali-modified material made of coal gangue is applied, and the land is directly rotary tilled. It should be noted that the alkali-modified material made of coal gangue is applied to the sandy loam black soil before direct rotary tillage, so that the alkali-modified coal gangue can be carried into the deeper layers during rotary tillage, thereby better improving the pore structure of the sandy loam black soil.

[0012] In a preferred embodiment of the present invention, the mass ratio of the coal gangue alkali-modified material to the soil is 3:7.

[0013] In a preferred embodiment of the present invention, the preparation method of the modifier is as follows: coal gangue obtained after passing through different sieves is placed in a 3% sodium hydroxide solution, stirred evenly, heated to 75°C, kept warm for 2 hours, and after the reaction is completed, it is naturally cooled, filtered, washed with water, and dried to obtain the coal gangue alkali-modified material.

[0014] Furthermore, the applied coal gangue alkali-modifying material is alkali-modified coal gangue that has passed through 0-2mm, 2-5mm, and 5-8mm sieves.

[0015] The beneficial effects of this invention are:

[0016] This invention innovates a soil conditioner method by applying alkali-modified coal gangue followed by rotary tillage, addressing issues such as high bulk density, heavy texture, and swelling / shrinking characteristics in sandy black soil. Coal gangue, rich in organic matter, increases soil water retention capacity and reduces particle compaction after application. Furthermore, it significantly enhances active carbon sources, providing carbon and energy for microorganisms, triggering an activation effect, accelerating carbon conversion, promoting the bonding within soil aggregates and between particles, ensuring an appropriate porosity ratio between large and small aggregates, and maintaining good soil structure and stability.

[0017] Smaller coal gangue particles have a larger specific surface area and more water-holding pores. Small-diameter coal gangue fills the smaller pores in the soil, combining with clay particles to form aggregates. This rearranges the soil pores, creating larger pores. From the perspective of coal gangue modification, modified coal gangue has more pores and a larger specific surface area, allowing for better contact with soil enzymes. This enzymatic reaction leads to faster nutrient release. Furthermore, the increased specific surface area provides more exchange sites for SiO₂ ions, offering more channels for nutrient storage and transport.

[0018] Alkali-modified coal gangue, as an exogenous organic material, produces organic matter that directly inhibits soil swelling and shrinkage. The organic acids produced during the microbial decomposition of exogenous organic materials, while providing humus, can dissolve CaCO3, forming Ca... 2+ As a bridge, it connects negatively charged humus and clay minerals to form a mineral-organic complex, which improves the soil's cementation capacity and stabilizes organic matter within the soil. This improves the rigid and clayey properties of sandy black soil while stabilizing the soil structure. Attached Figure Description

[0019] Figure 1 These are infrared spectral images of coal gangue before and after modification;

[0020] Figure 2 Images showing the mineral phase composition of coal gangue before and after modification;

[0021] Figure 3 Images showing the microstructure of coal gangue before and after modification;

[0022] Figure 4 Images showing the swelling and shrinkage properties of conventionally treated soil in the comparative example;

[0023] Figure 5 Images showing the swelling and shrinkage properties of soil treated with alkali-modified coal gangue according to the present invention in the embodiments;

[0024] Figure 6 This is a schematic diagram illustrating the treatment of soil source and organic carbon from alkali-modified coal gangue in the embodiment of the present invention, including the destination, accumulation, and net carbon balance. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0026] The embodiments of the present invention include:

[0027] This invention provides an application of a soil conditioner in improving the physical structure of sandy loam black soil. The conditioner is a coal gangue alkali-modified material. Before planting crops on sandy loam black soil, the coal gangue alkali-modified material is applied, and the land is directly rotary tilled.

[0028] Experimental location: Haizi Mine, Suixi County, Huaibei City, Anhui Province. The tested soil was sandy black soil with strong swelling and shrinkage properties. The plot area was 25 square meters. Alkali-modified coal gangue was applied on July 1, 2024, and sampling and testing were conducted on October 25, 2023.

[0029] Example 1: The technical solution of the present invention involves applying 3196.8 kg / mu of 0-2mm coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0030] Example 2: The technical solution of the present invention involves applying 3196.8 kg / mu of 0-2mm acid-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0031] The method for preparing the acid-modified coal gangue is as follows: the coal gangue obtained after passing through a 0-2mm sieve is placed into a 5% hydrochloric acid solution, stirred evenly, heated to 70℃, kept warm for 2 hours, and then cooled naturally after the reaction is completed. The mixture is then filtered, washed with water, and dried to obtain the acid-modified coal gangue sample.

[0032] Example 3: The technical solution of the present invention involves applying 3196.8 kg / mu of 0-2mm alkali-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0033] The alkaline coal gangue is prepared by: placing the coal gangue obtained after passing through a 0-2mm sieve into a 3% sodium hydroxide solution, stirring evenly, heating to 75℃, keeping warm for 2 hours, and then naturally cooling after the reaction is completed. The mixture is then filtered, washed with water, and dried to obtain the 0-2mm coal gangue alkaline modified material.

[0034] Example 4: The technical solution of the present invention involves applying 3196.8 kg / mu of 2-5mm coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0035] Example 5: The technical solution of the present invention involves applying 3196.8 kg / mu of 2-5mm acid-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0036] The preparation method of acid-modified coal gangue is the same as in Example 2.

[0037] Example 6: The technical solution of the present invention involves applying 3196.8 kg / mu of 2-5mm alkali-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0038] The preparation method of alkali-modified coal gangue is the same as in Example 3.

[0039] Example 7: The technical solution of the present invention involves applying 3196.8 kg / mu of 5-8mm coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0040] Example 8: The technical solution of the present invention involves applying 3196.8 kg / mu of 5-8 mm acid-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0041] The preparation method of acid-modified coal gangue is the same as in Example 2.

[0042] Example 9: The technical solution of the present invention involves applying 3196.8 kg / mu of 5-8 mm alkali-modified coal gangue after wheat harvest, and directly rotary tilling the soil to a depth of 20 cm when the field water holding capacity is 60%.

[0043] The preparation method of alkali-modified coal gangue is the same as in Example 3.

[0044] Comparative Example: A control crop was planted on the same plot of land and treated conventionally. The difference from Example 1 was that after wheat harvest, the soil was directly rotary tilled to a depth of 20 cm when the field water holding capacity was around 60%.

[0045] Experimental results:

[0046] 1. The trace element content of coal gangue is shown in Table 1. The pH of the coal gangue used in this paper is 9.66. At this pH, the contents of As, Pb, Cd, Cr, Cu, and Ni in the coal gangue sample are all lower than the screening values ​​for agricultural land soil pollution risk. The element contents meet the requirements for agricultural land in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018). The risk to the soil ecological environment is low, and it does not cause much pollution to the environment. It can be used for soil improvement.

[0047] Table 1. Trace element content in coal gangue and screening values ​​for soil pollution risk in agricultural land.

[0048] 2. By Figure 1 It can be seen that, compared with the absorption vibration peaks of coal gangue, acid-modified coal gangue and alkali-modified coal gangue did not show any new characteristic peaks, and their positions did not change significantly, indicating that the types of functional groups on the surface of coal gangue did not change significantly after modification. However, in the 900~1200 cm⁻¹ range... -1 The absorption peak at that point is a stretching vibration peak caused by the Si-O bond, and the intensity of the peak is significantly weakened, indicating that the Si-O bond has been broken and reorganized.

[0049] Depend on Figure 2As can be seen, the XRD pattern contains both sharp and broad peaks, indicating that the minerals exist primarily in crystalline and amorphous states. The diffraction peaks of the coal gangue before and after modification are similar, with no obvious new characteristic diffraction peaks appearing, suggesting that the phase composition did not change with the modification method, indicating that the modification method had little impact on the phase composition. However, after acid-base modification, the intensity of the quartz phase diffraction peaks decreased significantly, indicating that the internal crystal structure of the coal gangue was destroyed during the modification process, and some of the quartz phase dissolved. Furthermore, the appearance of "bun peaks" after coal gangue modification indicates that some of the quartz phase transformed into amorphous silica, suggesting that Si-O bond recombination improved the activity of beneficial elements in the coal gangue and enhanced its adsorption capacity.

[0050] Depend on Figure 3 It can be seen that the surface microstructure of coal gangue changes significantly after acid and alkali modification. Unmodified coal gangue has a relatively smooth surface and a densely packed structure, exhibiting a "layered" crystal structure, such as... Figure 3 As shown in a; however, the surface roughness of acid-modified and alkali-modified coal gangue is significantly aggravated, the lamellar structure is broken, and the number of pores is significantly increased, such as... Figure 3 As shown in b and 3c.

[0051] 3. The soil in the conventional control planting area exhibited stronger swelling and shrinkage properties (see...). Figure 4 The linear extension coefficient of the soil was as high as 0.0855, while the soil swelling and shrinkage problem was significantly alleviated by the technology of this invention (see...). Figure 5 The lowest linear extension coefficient of the soil was 0.0112 when 0-2 mm of alkali-modified coal gangue was added, a decrease of 86.90%, which changed the hazard level from high to low.

[0052] 4. Organic carbon content, soil bulk density, and total soil porosity are important indicators reflecting the quality of soil structure. In this experiment, the organic carbon content and bulk density of the top 0-2 cm soil were measured. The results are shown in Table 2. The technology of this invention significantly improved the organic carbon content, total porosity, and average pore diameter of the top 0-2 cm soil. Compared with conventional treatment, the organic matter content of the top 0-2 cm soil increased by 39.26-77.93%, the bulk density decreased by 25.60-37.5%, and the total porosity increased by 43.96-64.97%. This indicates that the technology of this invention significantly improves the soil structure of sandy loam black soil, significantly reduces soil bulk density, increases total porosity, and transforms the soil hazard level from severe to low-level hazard.

[0053] Table 2. Effects of different treatments on organic matter content, bulk density, and total porosity of the top 0-2cm soil layer.

[0054] 5. Based on the changes in the δ¹³C value of soil organic carbon, distinguish between "old carbon" from sandy loam black soil and "new carbon" formed by the decomposition of coal gangue, and calculate whether the formation of "new carbon" can compensate for the loss of "old carbon". Figure 6 It can be seen that, under the cultivation environment of this study, the organic carbon from soil and coal gangue had three fates throughout the entire cultivation period: (1) decomposition into CO2 and release into the atmosphere; (2) conversion into SOC and accumulation in the soil through leaching, soil microbial metabolites, and dead remains; and (3) errors in the experimental process (which were negligible in this experiment). The initial organic carbon content of the soil treated in the comparative example, Example 1, Example 2, and Example 3 was measured to be 5.34 g·kg⁻¹. -1 14.54 g·kg -1 20.23 g·kg -1 21.67 g·kg -1 At the end of the culture, the content was 4.96 g·kg. -1 14.11 g·kg -1 19.73 g·kg -1 21.11 g·kg -1 ( Figure 6 b、 Figure 6 c), the soil organic carbon content in the treatments of Examples 1, 2, and 3 was significantly increased by 184.48%, 297.78%, and 325.60% compared to the control (CK) treatment, respectively. "Old carbon" accounted for 24.27%, 17.69%, and 17.21% of the total soil organic carbon content, respectively, while "new carbon" accounted for 75.73%, 82.31%, and 82.79%. Furthermore, the net carbon balance, arranged from largest to smallest, was Example 3 > Example 2 > Example 1 (…). Figure 6 (d) indicates that the addition of alkali-modified coal gangue can promote the accumulation of soil organic carbon.

[0055] Conclusion: This embodiment demonstrates that the present invention can significantly increase the organic matter content of the 0-2 cm topsoil using alkali-modified coal gangue, with the best effect observed in Example 3 where 0-2 mm of alkali-modified coal gangue was added. Organic matter directly inhibits soil swelling and shrinkage, accelerates the transformation between carbon components, promotes the bonding within soil aggregates and between particles, ensures an appropriate porosity ratio between large and small aggregates, maintains good soil structure and stability, reduces soil hazard levels from high to low, significantly reduces soil bulk density, and increases total porosity.

[0056] The parts not covered in this technical solution can be implemented using existing technologies.

[0057] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. The application of a modifier in improving the physical structure of sandy black soil, characterized in that, The modifier is a coal gangue alkali-modified material.

2. The application according to claim 1, characterized in that, Before planting sand ginger black soil crops, apply coal gangue alkali-modified materials and directly rotary till the land.

3. The application according to claim 1, characterized in that, The mass ratio of the coal gangue alkali-modified material to the soil is 3:

7.

4. The application according to claim 1, characterized in that, The preparation method of the modifier is as follows: coal gangue obtained after passing through different sieves is placed in a 3% sodium hydroxide solution, stirred evenly, heated to 75°C, kept warm for 2 hours, and then cooled naturally after the reaction is completed. The mixture is then filtered, washed with water, and dried to obtain the coal gangue alkali-modified material.

5. The application according to any one of claims 1 to 4, characterized in that, The applied coal gangue alkali-modified material is alkali-modified coal gangue that has passed through 0-2mm, 2-5mm, and 5-8mm sieves.

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