Coal gangue-based sanding soil amendment and application thereof

Abstract

The application discloses a coal gangue-based sandy soil modifier and application thereof, and belongs to the technical field of soil improvement. The modifier is composed of a basic component and a composite component, wherein the basic component is coal gangue, and the composite component is composed of straws and rotten leaves. The mass percentage of the basic component is 1-5%, and the mass ratio of the straws to the rotten leaves in the composite component is (1-4):(1-4). The modifier provided by the application can simultaneously, quickly and durably increase the contents of organic matter, total nitrogen and total phosphorus in sandy soil, significantly improve the problems of loose structure, poor water and fertilizer retention capacity and extreme nutrient deficiency of the sandy soil, and improve the soil fertility from an extremely low level to a high level, thereby effectively overcoming the problems of single effect, poor nutrient synergy, short duration and high cost of the existing modifier. The modifier is suitable for ecological restoration and fertility improvement of flowing sandy land, semi-fixed sandy land and sandy farmland.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, specifically to a coal gangue-based soil conditioner for desertification and its application. Background Technology

[0002] Desertified soils generally suffer from problems such as loose structure, excessive porosity, poor water and fertilizer retention capacity, and deficiency of organic matter and nitrogen and phosphorus nutrients, leading to a decline or even loss of land productivity and ecosystem degradation. Soil organic matter, total nitrogen, and total phosphorus are the core indicators for evaluating soil fertility, and all three directly affect the level of soil nutrient supply and crop growth potential.

[0003] Coal gangue, as a solid waste from mining industry, is rich in various mineral nutrients. It can effectively regulate soil pore structure, delay nutrient leaching, reduce pH in saline-alkali soils, and promote microbial diversity, thus possessing good potential for soil improvement. Studies have shown that the particle size and proportion of coal gangue significantly affect soil physicochemical properties. Small-particle coal gangue (0.075-2 mm) can improve soil porosity and water retention, promoting plant germination; however, excessively high proportions of coal gangue can inhibit plant growth. A mixture of vermiculite and coal gangue as a matrix, combined with decomposed straw and biochar, can enhance soil water transport and infiltration, and increase the content of available nitrogen, available phosphorus, and available potassium. A combination of coal gangue with biochar and polyacrylamide can reduce matrix infiltration and enhance water retention, but the improvement effect significantly decreases as the proportion of coal gangue exceeds 50%.

[0004] Patent CN120476742A discloses a method for land improvement using coal-based solid waste in conjunction with agricultural waste. It involves mixing coal gangue, construction waste, and organic fertilizer to prepare activated artificial soil, suitable for mine land remediation. Patent CN116376562A discloses a method for preparing a novel coal gangue soil conditioner, composed of modified coal gangue, vermiculite, potassium humate, phosphogypsum powder, ammonium sulfate, and potassium phosphate. This conditioner has a good improvement effect on alkaline soil and can significantly increase seedling survival rate and crop yield. Patent CN118272096A discloses a coal gangue soil conditioner, its preparation method, and its application. Its main components include crushed coal gangue, crushed corn stalks, livestock and poultry manure, compound microbial agents, high-molecular water-absorbing and water-retaining granules, and compound microbial agents. This conditioner can improve soil physicochemical properties, increase nitrogen, phosphorus, potassium, and organic matter content, and promote crop growth.

[0005] However, existing soil improvement technologies mostly employ single-element coal gangue or simple compound systems, which are insufficient to simultaneously and efficiently increase soil organic matter, total nitrogen, and total phosphorus content. They often focus on a single nutrient indicator while neglecting the synergistic improvement of overall fertility. Furthermore, existing research is largely concentrated on ordinary farmland soils, lacking systems specifically designed for "extremely poor" sandy soils.

[0006] Therefore, there is an urgent need to develop a soil conditioner that can adapt to the characteristics of desertified soil, is low in cost, and can rapidly, synergistically, and sustainably improve soil nutrients, so as to meet the actual needs of ecological restoration and fertility improvement of desertified soil. Summary of the Invention

[0007] In view of this, the present invention provides a coal gangue-based soil conditioner for desertified soil and its application. The conditioner uses coal gangue as the basic component and straw and decomposed leaves as composite components. By optimizing the ratio of each component, a composite improvement system for the synergistic utilization of industrial solid waste and agricultural waste is constructed, so as to achieve the simultaneous, rapid and lasting improvement of organic matter, total nitrogen and total phosphorus in desertified soil.

[0008] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a coal gangue-based soil conditioner for desertified soil, the soil conditioner being composed of basic components and composite components; The basic component is coal gangue; The composite component consists of straw and decaying leaves.

[0009] Preferably, the mass percentage of the basic components in the sandy soil conditioner is 1% to 5%.

[0010] Preferably, the mass percentage of the basic component in the sandy soil conditioner is 2%.

[0011] Preferably, the mass ratio of straw to leaf decay in the composite component is (1~4):(1~4); the straw is selected from at least one of corn straw, wheat straw, rice straw, cotton straw, and sunflower straw; the leaf decay is selected from at least one of poplar leaf decay, sycamore leaf decay, paulownia leaf decay, birch leaf decay, elm leaf decay, willow leaf decay, oak leaf decay, and locust leaf decay.

[0012] Preferably, the coal gangue is the undersize material that has been crushed and passed through an 80-100 mesh sieve.

[0013] Preferably, the straw is the undersize material that has been dried, crushed, and passed through an 80-mesh sieve; The decayed leaves are the undersize material that has been dried, crushed, and passed through an 80-mesh sieve.

[0014] Secondly, the present invention provides the application of a coal gangue-based soil conditioner for the remediation and improvement of desertified soil as described in any of the preceding claims.

[0015] Preferably, the soil conditioner is applied by broadcasting, trenching, or mixing with soil.

[0016] The beneficial effects of this invention are: 1. This invention constructs a composite improvement system for industrial solid waste and agricultural waste by compounding coal gangue with straw and leaf mold. Experimental results show that this improver can simultaneously and significantly increase the content of organic matter, total nitrogen, and total phosphorus in sandy soils, overcoming the problem that existing improvers mostly focus on improving a single nutrient and are difficult to achieve comprehensive fertility improvement. Compared with single components, the compounding of straw and leaf mold shows significant synergistic effects in organic matter, total nitrogen, and total phosphorus, achieving a comprehensive improvement in the overall fertility of sandy soils.

[0017] 2. The soil conditioner provided by this invention can rapidly replenish soil organic matter and nitrogen and phosphorus nutrients in the early stages of application, meeting the early growth needs of plants. Simultaneously, it can continuously release nutrients in the middle and later stages, maintaining a high nutrient level and exhibiting good long-term stability. Different formulations of the conditioner can achieve differentiated nutrient release patterns according to actual needs, such as short-term explosive growth, steady improvement in the middle stage, or continuous accumulation in the later stage, effectively overcoming the shortcomings of existing conditioners, such as short action cycles and unstable nutrient release.

[0018] 3. The improver provided by this invention can rapidly, synergistically and persistently enhance the core fertility indicators of desertified soil, effectively improving problems such as loose structure, nutrient deficiency, and poor water and fertilizer retention capacity of desertified soil. It provides stable and sufficient nutrient support for plant growth, significantly improves the survival rate, growth rate and biomass of vegetation on desertified land, accelerates the ecological restoration process of desertified land, restores land productivity, and has important ecological and economic benefits. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the manufacturer's recommendations. Unless otherwise stated, percentages and parts are weight percentages and weight parts. Unless otherwise specified, the experimental materials and reagents used in the following embodiments are commercially available.

[0020] Unless otherwise specified, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should be noted that the terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the exemplary embodiments of this application.

[0021] The technical solution provided by this invention: A coal gangue-based soil conditioner for desertified soil, the soil conditioner being composed of basic components and composite components; The mass percentage of the basic component is 1% to 5%, wherein the basic component is coal gangue; The composite component is composed of straw and decaying leaves in a mass ratio of (1~4):(1~4); the straw is selected from at least one of corn straw, wheat straw, rice straw, cotton straw, and sunflower straw; the decaying leaves are selected from at least one of poplar leaves, sycamore leaves, paulownia leaves, birch leaves, elm leaves, willow leaves, oak leaves, and locust leaves. The coal gangue is the undersize material that has been crushed and passed through an 80-100 mesh sieve; The straw is the material that has been dried, crushed and passed through an 80-mesh sieve; The decayed leaves are the undersize material that has been dried, crushed, and passed through an 80-mesh sieve.

[0022] A method for preparing a coal gangue-based soil conditioner for desertified soil includes the following steps: Add straw and decaying leaves to coal gangue, mix well, and let it ferment at room temperature for 3-5 days to obtain a coal gangue-based soil conditioner for desertification.

[0023] The present invention will be further illustrated below with reference to the embodiments.

[0024] Example 1 A coal gangue-based soil conditioner for desertification is composed of 2% coal gangue and 98% composite components (the mass ratio of corn stalks to poplar leaf decay is 1:4).

[0025] Coal gangue is the undersize material that has been crushed and passed through an 80-mesh sieve.

[0026] The straw was naturally air-dried and then crushed using a high-speed pulverizer and passed through an 80-mesh standard sieve to remove impurities. The decayed leaves were naturally dried, then pulverized using a pulverizer and passed through an 80-mesh sieve.

[0027] Example 2 A coal gangue-based soil conditioner for desertification is composed of 2% coal gangue and 98% composite components (the mass ratio of corn stalks to poplar leaf decay is 2:3).

[0028] Example 3 A coal gangue-based soil conditioner for desertification is composed of 2% coal gangue and 98% composite components (the mass ratio of corn stalks to poplar leaf decay is 1:1).

[0029] Example 4 A coal gangue-based soil conditioner for desertification is composed of 2% coal gangue and 98% composite components (the mass ratio of corn stalks to poplar leaf decay is 3:2).

[0030] Example 5 A coal gangue-based soil conditioner for desertification is composed of 2% coal gangue and 98% composite components (the mass ratio of corn stalks to poplar leaf decay is 4:1).

[0031] Comparative Example 1 A coal gangue-based soil conditioner for desertification, consisting of 2% coal gangue and 98% poplar leaf decay.

[0032] Comparative Example 2 A coal gangue-based soil conditioner for desertification, consisting of 2% coal gangue and 98% corn stalks.

[0033] The only difference between the coal gangue-based soil conditioners provided in the above embodiments and comparative examples is the difference in components and proportions, as shown in Table 1.

[0034] Table 1. Mass percentages of basic and composite components in the coal gangue-based sandy soil conditioners provided in each embodiment and comparative example, and the mass ratio of straw to decaying leaves in the composite components. Application examples Soil samples from 0-20 cm depth were collected, spread out in a ventilated area to air dry, ground, and passed through an 80-mesh nylon sieve to remove gravel, plant debris, and other impurities. Initial organic matter, total nitrogen, and total phosphorus content were measured. The coal gangue-based soil conditioner prepared in the above examples and comparative examples was thoroughly mixed with the sandy soil, with the sandy soil added at four times the amount of the composite component. A blank control group (containing only sandy soil, without any soil conditioner) was set up. Each group had three replicates. The mixtures were incubated at 15-25℃ to investigate the effects of the conditioner application from week 1 to week 16 on soil organic matter, total phosphorus, and total nitrogen content.

[0035] Table 2. Nutrient Classification Standards of the Second National Soil Survey Table 3. Effects of different soil amendments on soil organic matter content As shown in Table 3, there are significant differences in the improvement effect and dynamic changes of the organic matter content of sandy soil by different ratios of soil conditioners (P<0.05). The coal gangue-based soil conditioner provided by this invention can significantly improve the organic matter content of sandy soil, and the improvement effect of different ratio treatment groups is significantly different. The organic matter content of the blank control group is 6.9292 g / kg. The increase in organic matter content of each conditioner treatment group is generally between 2 and 6 times, indicating that the conditioners can significantly improve the organic matter content of sandy soil.

[0036] From a temporal dynamic perspective, the soil organic matter content generally exhibited a pattern of "rapid increase in the initial stage, fluctuation and adjustment in the middle stage, and stabilization in the later stage." Specifically, during the first week of cultivation, the organic matter content of each amendment treatment group increased by 2.42 to 3.40 times compared to the blank control group, indicating that the amendment could rapidly replenish soil organic matter. The period from the third to the sixth week was a period of fluctuation, with each group showing peak values ​​successively: the Example 5 group reached the highest value of the entire experiment (44.62 g / kg) in the sixth week; the Example 3 group showed a double peak in the third and fifth weeks, approximately 42.45 g / kg, suggesting that the release rate of organic matter from the amendment and the rate of microbial decomposition were in dynamic equilibrium during this stage. Continuing cultivation until the 16th week, the organic matter content of each amendment treatment group tended to stabilize, with the Example 5 group still maintaining above 40 g / kg, indicating that when the straw to leaf decay mass ratio is 4:1, long-term stable accumulation of organic matter can be achieved, effectively improving the state of organic matter deficiency in sandy soils.

[0037] According to the nutrient grading standards of the Second National Soil Survey (Table 2), the organic matter content of the blank control group was at level V, indicating an extremely deficient organic matter and very low soil fertility, consistent with the typical characteristics of sandy soil, which could not meet the normal growth needs of plants. All treatment groups treated with soil amendments were able to rapidly and significantly increase the organic matter content, moving it away from level V and improving it to levels I to III. Among them, the organic matter content of the Example 5 group reached 44.62 g / kg and 41.34 g / kg in weeks 6 and 16, respectively, both exceeding 40 g / kg and reaching level I, showing excellent initial improvement effect and long-term stability, with the best improvement effect; the organic matter content of the Example 3 group was approximately 42.45 g / kg in weeks 3 and 5, also reaching level I, with outstanding short-term improvement effect; the Example 2 and Example 4 groups were mostly at level II throughout the process, with high levels of soil organic matter and stable improvement effect; the Example 1 group was mostly at level III, with moderate soil fertility, effectively improving the current situation of soil organic matter deficiency.

[0038] Further comparative examples and comparative cases show that the overall effect of the straw and leaf decomposition compound group is significantly better than that of the single component, indicating that straw and leaf decomposition have a synergistic effect in improving organic matter.

[0039] Table 4. Effects of different soil amendments on total phosphorus content. Table 4 shows that different ratios of coal gangue-based soil conditioners significantly improved the total phosphorus content of sandy soils and exhibited dynamic changes (P<0.05). The total phosphorus content in the blank control group remained consistently at 0.2342 g / kg, falling within the V level of the nutrient grading standards of the Second National Soil Survey, indicating extreme phosphorus deficiency and very low soil phosphorus fertility, failing to meet the basic phosphorus requirements for plant growth. Compared to the blank control group, the total phosphorus content in each conditioner treatment group was significantly higher than that in the control group at different cultivation stages, indicating that the conditioners effectively improved the total phosphorus content of sandy soils.

[0040] From a time-dynamic perspective, the total phosphorus content of each amendor treatment group generally exhibited a pattern of "fluctuating upward in the early stage, reaching a peak in the middle stage, and stabilizing in the later stage." In the first week of cultivation, the total phosphorus content of each amendor treatment group was significantly higher than that of the blank control group. Comparative Example 2 and Example 5 showed particularly outstanding performance in the early stage, providing sufficient available phosphorus to the soil in a short period to meet the early growth needs of plants. Peak values ​​appeared successively in the third to sixth weeks. Comparative Example 2 reached 1.2219 g / kg in the fifth week, reaching Level I, which is considered an extremely high level of phosphorus fertility, demonstrating a burst-like short-term phosphorus enhancement effect. This fully reflects the outstanding role of a single straw component in rapidly increasing total phosphorus in a short period. Example 3, Example 4, and Example 5 also maintained high total phosphorus content during this stage, with a stable and significant overall enhancement effect. During this stage, the straw and decaying leaves in the amendor gradually decomposed and released phosphorus, combined with the phosphorus retention and slow-release effect of coal gangue, maintaining a high level of total phosphorus in the soil. By week 16, the total phosphorus content of each soil amendment treatment group tended to stabilize, demonstrating good long-term maintenance ability. Among them, the total phosphorus content of Example 4 reached 0.9461 g / kg, which was the highest among all treatment groups, demonstrating a strong long-term phosphorus supply capacity. The total phosphorus content of Example 5 and Comparative Example 2 also remained at a high level. The total phosphorus content of Example 1 remained at level III throughout the process, with a medium level of phosphorus fertility, which could effectively improve the soil's total phosphorus deficiency and showed strong stability.

[0041] Comparing different treatment groups reveals that Comparative Example 2, with a single straw component, showed the most significant effect in short-term total phosphorus enhancement, demonstrating the advantage of rapid phosphorus replenishment. Comparative Example 1, with a single leaf decomposition component, showed a stable and long-lasting effect in enhancing total phosphorus. In the various embodiments of the straw and leaf decomposition compound in this invention, the dual requirements of rapid short-term enhancement and stable long-term supply can be met. Different ratios can achieve differentiated total phosphorus regulation effects. Among them, Example 4 showed a significant long-term advantage, Example 5 showed a balanced enhancement effect throughout the process, and Example 3 showed outstanding performance in the middle stage, which can meet the soil phosphorus enhancement needs of different desertification levels and different improvement goals. Meanwhile, the overall improvement effect of all embodiments was significantly better than that of Comparative Example 1, which used only leaf mold, and better than Comparative Example 2, which used only straw. This fully demonstrates that when straw and leaf mold are used in combination, there is a significant synergistic effect in improving total phosphorus content. This can overcome the shortcomings of single-component improvement, which has outstanding short-term effects but insufficient long-term effects or stable improvement but limited increase. It can achieve a rapid, efficient and lasting increase in total phosphorus content in desertified soil, thoroughly improve the problem of extreme phosphorus deficiency in desertified soil, and provide stable and sufficient phosphorus nutrition support for ecological restoration and plant growth in desertified land.

[0042] Table 5. Effects of different soil amendments on total nitrogen content. Table 5 shows that different ratios of coal gangue-based soil conditioners significantly improved the total nitrogen content of sandy soils and exhibited dynamic changes (P<0.05). The total nitrogen content in the blank control group remained consistently at 0.32 g / kg, at level VI, indicating extreme nitrogen deficiency and very low soil nitrogen fertility, completely failing to meet the basic nitrogen requirements for plant growth—a core characteristic of low fertility in sandy soils. Compared to the blank control group, the total nitrogen content in each conditioner treatment group was significantly higher than that of the control group at different cultivation stages, raising soil nitrogen fertility from level VI (extreme deficiency) to a medium-high level. This demonstrates that the conditioner of this invention can effectively improve the total nitrogen content of sandy soils, with a significant improvement effect.

[0043] From a time-dynamic perspective, the total nitrogen content of each treatment group generally exhibited a pattern of "fluctuating increase—steady improvement in the middle stage—explosive growth in the later stage," which shares similarities with the patterns of organic matter and total phosphorus, while also reflecting the unique late-stage accumulation characteristics of nitrogen. In the first week of cultivation, the total nitrogen content of each amendment treatment group was significantly higher than that of the blank control group. The most significant increase was observed in Example 3 group, reaching 1.82 g / kg, which is at level II. Example 4 group and Comparative Example 2 also showed significant initial improvement effects. The remaining groups were also significantly better than the blank control, indicating that the amendment can rapidly replenish soil nitrogen in a short period, providing crucial nitrogen support for early plant emergence and growth. Weeks 3 to 6 represent the mid-term steady improvement phase, during which the total nitrogen content in each group continued to climb and successively reached peak values. By week 5, Example 1 and Example 2 reached 2.39 g / kg and 2.38 g / kg respectively, both exceeding 2.0 g / kg and reaching Level I, demonstrating excellent short-term nitrogen enhancement capabilities. Comparative Example 2 reached 2.12 g / kg in week 5, also reaching Level I. By week 6, Example 1 further increased to 2.46 g / kg, the highest value during the same period, Comparative Example 1 reached 2.24 g / kg, and Example 2 reached 2.02 g / kg, all at high levels. By week 16 of cultivation, the total nitrogen content in each treatment group showed an explosive increase, with a significant overall improvement. Among them, the highest value among all treatment groups was 3.46 g / kg in Example 2, 3.44 g / kg in Comparative Example 1, 3.28 g / kg in Example 1, 3.23 g / kg in Example 4, and 3.20 g / kg in Example 5, all exceeding 3.0 g / kg and reaching Level I. The values ​​of 2.78 g / kg in Example 3 and 2.78 g / kg in Comparative Example 2 were both at Level II. This indicates that the soil conditioner has a strong nitrogen accumulation capacity in the later stages and can provide a long-lasting and sufficient nitrogen supply for sandy soils.

[0044] Comparison of different treatment groups revealed that Comparative Example 1, with a single leaf mold component, exhibited extremely strong nitrogen accumulation capacity in the later stages, but experienced significant fluctuations in the early stages; Comparative Example 2, with a single straw component, showed balanced nitrogen release and strong stability, but its accumulation capacity was relatively weak in the later stages; while the various embodiments of the straw and leaf mold compound in this invention can simultaneously meet the dual needs of rapid short-term improvement and stable long-term supply. Different ratios can achieve differentiated total nitrogen regulation effects. Example 2 showed the most significant long-term advantage in the later stages, Example 1 showed a steady increase throughout the process, combining both short-term and long-term advantages, Examples 4 and 5 showed balanced nitrogen release and significant accumulation effects in the later stages, and Example 3 showed outstanding short-term performance followed by stabilization in the later stages. Furthermore, the overall improvement effect of all embodiments was significantly better than that of single components, especially in terms of later nitrogen accumulation, where the compound groups performed better overall, fully demonstrating that the combined use of straw and leaf mold has a significant synergistic effect in improving total nitrogen. The amendment provided by this invention can achieve rapid, efficient, and sustained improvement in the total nitrogen content of desertified soils, providing stable and sufficient nitrogen nutrition support for the ecological restoration of desertified land and plant growth.

[0045] 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 structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures 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 coal refuse-based sand-based soil amendment, characterized in that, The desertified soil conditioner is composed of basic components and composite components; The basic component is coal gangue; The composite component consists of straw and decaying leaves.

2. The coal gangue-based soil conditioner for desertified soil according to claim 1, characterized in that, The mass percentage of the basic components in the sandy soil conditioner is 1% to 5%.

3. The coal gangue-based soil conditioner for desertified soil according to claim 2, characterized in that, The basic component in the sandy soil conditioner has a mass percentage of 2%.

4. The coal gangue-based soil conditioner for desertified soil according to claim 1, characterized in that, The mass ratio of straw to decaying leaves in the composite component is (1~4):(1~4); the straw is selected from at least one of corn straw, wheat straw, rice straw, cotton straw, and sunflower straw; the decaying leaves are selected from at least one of poplar decaying leaves, sycamore decaying leaves, paulownia decaying leaves, birch decaying leaves, elm decaying leaves, willow decaying leaves, oak decaying leaves, and locust decaying leaves.

5. The coal gangue-based soil conditioner for desertified soil according to claim 1, characterized in that, The coal gangue is the undersize material that has been crushed and passed through an 80-100 mesh sieve.

6. The coal gangue-based soil conditioner for desertified soil according to claim 1, characterized in that, The straw is the material that has been dried, crushed and passed through an 80-mesh sieve; The decayed leaves are the undersize material that has been dried, crushed, and passed through an 80-mesh sieve.

7. The application of a coal gangue-based soil conditioner as described in any one of claims 1-6 in the remediation and improvement of desertified soil.

8. The application according to claim 7, characterized in that, The soil conditioner for desertification can be applied by broadcasting, trenching, or mixing with soil.

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