Acid soil improver based on coal water slurry gasification slag, preparation method thereof and improvement method

Abstract

The invention belongs to the technical field of soil amendments, and particularly relates to an acid soil amendment based on coal water slurry gasification slag and a preparation method and an amendment method of the acid soil amendment. The acid soil improver based on the coal water slurry gasified slag comprises the following components in parts by mass: 10-60 parts of gasified coarse slag, 0-20 parts of gasified fine slag, 1-5 parts of bentonite and 5-10 parts of humus, and the humus is obtained by fermenting pigeon manure and chicken manure with bacillus amyloliquefaciens, then adding bacillus subtilis, fermenting and sterilizing. The coal chemical industry solid waste gasification slag is used as a core improvement raw material, and is matched with the humus and the bentonite, so that the physical and chemical properties of the acid soil can be improved, the problems that the gasification slag occupies land and pollutes the environment due to long-term stockpiling are solved, and the resource recycling of industrial wastes is realized.

Description

Technical Field

[0001] This invention belongs to the field of soil conditioner technology, specifically relating to an acid soil conditioner based on coal-water slurry gasification slag, its preparation method, and its improvement method. Background Technology

[0002] Acidic soil is one of the most widely distributed soil types in southern China. It is characterized by strong acidity, compact soil structure, poor drainage and aeration, vigorous capillary action, and easy nutrient loss. These problems severely restrict the development of crop roots and the absorption and utilization of water and nutrients, thus affecting agricultural production efficiency and the sustainability of the ecological environment.

[0003] Traditional methods for improving acidic soils mainly involve applying chemical or natural soil conditioners such as lime, gypsum, and organic fertilizers. However, lime-based conditioners have drawbacks such as large dosage requirements, short-lived effects, and a tendency to cause soil compaction; organic fertilizers have limited sources and long decomposition cycles, making it difficult to meet the needs of large-scale soil improvement; and existing chemical soil conditioners generally suffer from high costs, a tendency to cause secondary pollution, and low market penetration.

[0004] Coal-water slurry gasification technology is a core technology in the coal chemical industry. During the gasification process, a large amount of solid waste—gasification slag—is generated, including coarse and fine gasification slag. The coarse gasification slag, after high-temperature melting and quenching, is discharged from the bottom of the gasifier. Its particle size is concentrated between 4750-10000 μm, with a high sand-like density, which can improve soil pore structure. The fine gasification slag is obtained by being carried out by the gas flow and then washed and precipitated. Its particle size is less than 1000 μm, with a high clay-like density and strong adsorption capacity. Long-term stockpiling of this gasification slag not only occupies land resources but may also cause environmental pollution; its resource utilization has become an urgent problem to be solved in the industry.

[0005] In existing technologies, research on the use of coal-based solid waste for soil improvement mainly focuses on fly ash, primarily targeting saline-alkali soils or aeolian sandy soils. For example, the acidic soil conditioner disclosed in Chinese patent CN118956409B, while targeting acidic soils, does not address the core issue of poor pore structure and is costly, lacking specific improvement solutions tailored to the structural characteristics of acidic soils. For instance, some patented fly ash conditioners mainly focus on adjusting soil pH, offering limited improvement to core issues such as poor drainage and poor pore structure in acidic soils. Furthermore, some solutions require the addition of microbial agents or organic matrix, resulting in complex processes and high costs.

[0006] Therefore, developing a simple, effective, low-cost, and targeted method for improving acidic soil, and utilizing gasification slag to achieve the dual goals of resource utilization of industrial waste and soil improvement, is of great practical significance. Summary of the Invention

[0007] The purpose of this invention is to provide an acid soil conditioner based on coal-water slurry gasification slag, its preparation method, and its improvement method. By compounding coal chemical solid waste gasification slag with acidic soil in a specific ratio, the structure of acidic soil is effectively improved, drainage and aeration are enhanced, soil bulk density is reduced, and ecological improvement of acidic soil and resource utilization of industrial waste are achieved.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A soil conditioner based on coal-water slurry gasification slag comprises the following components in parts by weight: 10-60 parts coarse gasification slag, 0-20 parts fine gasification slag, 1-10 parts bentonite, and 1-15 parts humus. The humus is obtained by first fermenting pigeon manure and chicken manure with Bacillus amyloliquefaciens, then adding Bacillus subtilis for further fermentation, followed by sterilization.

[0009] This invention uses specific strains for gradient fermentation and achieves targeted humification through staged inoculation. This fermentation method can increase the humic acid content and produce a synergistic effect with gasification slag. The resulting amendment can increase the sand content of acid soil, reduce the bulk density, increase the total porosity, and stabilize the pH above 6, thus solving the problems of low activity of single fermentation microorganisms and incomplete improvement of acid soil.

[0010] Preferably, the components include the following parts by weight: 40-60 parts of coarse gasification slag, 10-20 parts of fine gasification slag, 1-5 parts of bentonite, and 5-10 parts of humus.

[0011] Preferably, the method for preparing the humic substance includes the following steps: (1) Mix pigeon droppings and chicken droppings, add water, and obtain fermentation raw materials; (2) Add Bacillus amyloliquefaciens to the fermentation raw materials, mix well, and carry out the first aerobic fermentation; (3) Continue to add Bacillus subtilis, mix well, and carry out the second aerobic fermentation; (4) After the fermented material is sterilized, it is cooled to room temperature to obtain humus.

[0012] Preferably, the strain number of Bacillus subtilis is Delf-28596, and the strain number of Bacillus amyloliquefaciens is Delf-27787.

[0013] Preferably, the mass ratio of Bacillus amyloliquefaciens to Bacillus subtilis is (1-2):(0.5-1).

[0014] Preferably, the mass ratio of pigeon droppings to chicken droppings is 1:(2-3).

[0015] This invention uses pigeon manure and chicken manure as raw materials, which are more suitable for acid soil improvement. After decomposition, pigeon manure is slightly alkaline and rich in pectin and other easily humifiable components, which complement the high nitrogen content of chicken manure. This provides a special nutrient substrate for specific microorganisms, resulting in a high humification coefficient and more alkaline groups in the generated humus. When applied to acid soil, it not only neutralizes active acids through the humus buffer system, but also works with bentonite to bind sand particles, reducing soil compaction and significantly enhancing the improvement effect on the physical and chemical properties of acid soil.

[0016] It should be noted that the microbial strains used in this invention are only used for fermentation. Sterilization is performed after fermentation. The effective components in the improver do not contain the microbial strains, and the microbial strains do not participate in the improvement process. The microbial strains used in fermentation serve only as humification catalysts. There are no live bacteria residues after sterilization. The improvement effect is achieved through the synergistic effect of humus, gasification slag, and bentonite.

[0017] Preferably, the gasification slag has a particle size of 4750-10000 μm and a bulk density of 0.86-0.89 g. cm - ³, saturated water content is 63-66%, and cation exchange capacity is 7.80-7.82 cmol·kg⁻¹. - ¹, the loss on ignition rate is 16-17%.

[0018] Preferably, the gasification slag has a particle size of <1000μm and a bulk density of 0.35-0.37g·cm³. - ³, saturated water content 224-225%, cation exchange capacity 3.87-3.89 cmol·kg⁻¹ - ¹, the loss on ignition rate is 28-30%.

[0019] Preferably, the bentonite comprises the following components by mass percentage: SiO2 content of 60%-75wt%, Al2O3 content of 12%-20%; total content of CaO, MgO, Na2O and K2O of 3%-8%, with the remainder being impurities.

[0020] The method for preparing the acid soil conditioner based on coal-water slurry gasification slag includes the following steps: mixing all raw materials evenly to obtain the acid soil conditioner based on coal-water slurry gasification slag.

[0021] The method for improving acidic soil based on coal-water slurry gasification slag includes the following steps: (1) Mix 10-30 parts by weight of the amendment and 70-90 parts by weight of the acid soil to obtain a mixture; (2) After the soil thaws in spring, spread the mixture evenly on the surface of the acidic soil. The amount of mixture used is 9000-13000 kg·hm. - ², after plowing, rotary tillage to a depth of 20-30cm, and then sowing.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention uses gasification slag, a solid waste product from coal chemical industry, as the core improving raw material, solving the problems of long-term land occupation and environmental pollution caused by the stockpiling of gasification slag. It achieves the resource-based recycling of industrial waste, aligning with the concept of green development. Compared to traditional chemical improvers, this invention utilizes industrial waste, reducing costs by more than 40%, and requires no complex processing techniques. Field application only requires spreading and rotary tillage, making it suitable for large-scale promotion and application. Furthermore, the heavy metal content in the gasification slag meets the GB / T23349-2009 fertilizer ecological index standard. Leaching tests show that when gasification slag is applied to a thickness of less than 10 cm, the heavy metal content in the leachate meets the GB / T14848-93 groundwater quality Class II standard, and will not cause harm to the soil environment or human health.

[0023] 2. The improved method of this invention addresses the defects of acidic soil, such as compaction, poor drainage, and strong capillary action. The large-particle sand component of the gasification coarse slag can increase the proportion of large pores and weaken capillary action; the adsorption characteristics of the gasification fine slag can fill soil gaps, and together with humus and bentonite, the synergistic effect significantly reduces the bulk density of acidic soil, optimizes the pore structure, and gradually transforms the soil texture from silty loam to sandy loam, greatly improving drainage and aeration; the essential plant nutrients such as Fe, Ca, and Mg contained in the gasification slag can supplement the nutrients of acidic soil; its high organic carbon content (high loss on ignition) can increase the soil organic matter level, and the cation exchange capacity characteristics enhance the soil's fertilizer retention capacity, effectively reducing nutrient loss. Attached Figure Description

[0024] Figure 1 The images show the scanning electron microscope (SEM) analysis of the gasification slag. a and b represent the coarse gasification slag; a is a 10 μm scale bar, and b is a 100 μm scale bar. Figure 2 The results show the particle size composition of acid soil with different gasification slag mixes in Examples 1-8; Figure 3 The results show the porosity of different gasification slags and acid soils in Examples 1-8, where a is CK and PF-1-8 are formulations 1-8. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The raw materials used in the following embodiments of the present invention are commercially available products: Bacillus subtilis, catalog number Delf-28596, Hefei Wanwu Biotechnology Co., Ltd., live bacteria content: 100 billion CFU / g.

[0027] Bacillus amyloliquefaciens, catalog number Delf-27787, manufactured by Hefei Wanwu Biotechnology Co., Ltd., with a live bacteria content of 100 billion CFU / g.

[0028] The solid waste gasification coarse slag and gasification fine slag from coal chemical production are collected. The gasification slag comes from Ordos Uxin Banner Boda Fertilizer Co., Ltd., and its preparation process is as follows: after adding water-coal slurry additives to the raw coal, it enters the coal mill and mixes with water to make water-coal slurry. The water-coal slurry and oxygen are injected into the combustion chamber of the gasifier and burned at a high temperature of 1300℃. The combustion residue is cooled and solidified in the quench chamber, crushed by the slag crusher, and then collected and processed to form gasification slag.

[0029] The gasification slag has a particle size of 4750-10000 μm and a bulk density of 0.88 g. cm - ³, saturated water content is 65%, cation exchange capacity is 7.81 cmol·kg⁻¹ - ¹, the loss on ignition rate is 16%.

[0030] The gasification slag has a particle size of <1000μm and a bulk density of 0.36g·cm³. - ³, saturated water content is 224%, cation exchange capacity is 3.88 cmol·kg⁻¹ - ¹, the loss on ignition rate is 29%.

[0031] The bentonite comprises the following components by mass percentage: 65% SiO2, 18% Al2O3, 1.2% CaO, 1.6% MgO, 0.7% Na2O, and 1.5% K2O, with the remainder being impurities; the bentonite particle size is less than 200 mesh.

[0032] Example 1 This embodiment provides an acid soil conditioner based on coal-water slurry gasification slag, comprising the following components in parts by weight: 10 parts coarse gasification slag, 0 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0033] The method for preparing the humic substance includes the following steps: (1) Mix pigeon manure and chicken manure at a mass ratio of 1:2, add water, and obtain fermentation raw material with a water content of 52wt%; (2) Add 1% of Bacillus amyloliquefaciens by weight of fermentation raw materials to the fermentation raw materials, mix evenly, and carry out the first aerobic fermentation. The first aerobic fermentation time is 6 days. When the internal temperature of the pile exceeds 50℃, turn it over immediately; if the threshold is not reached, turn it over once every 3 days.

[0034] (3) Continue to add Bacillus subtilis at a mass of 0.5% of the fermentation raw materials, mix evenly, and carry out the second aerobic fermentation. The second aerobic fermentation time is 12 days. When the internal temperature of the pile exceeds 50℃, turn it over immediately; if the threshold is not reached, turn it over once every 3 days. (4) Spread the fermented material evenly to a thickness of 6cm, heat it to sterilize at 70℃, maintain a relative humidity of 65%, and sterilize for 30 minutes. After sterilization, cool it to room temperature to obtain humus.

[0035] The method for preparing the acid soil conditioner based on coal-water slurry gasification slag includes the following steps: mixing all raw materials evenly to obtain the acid soil conditioner based on coal-water slurry gasification slag.

[0036] The method for improving acidic soil based on coal-water slurry gasification slag includes the following steps: (1) Mix 20 parts of amendment and 80 parts of acid soil to obtain a mixture; (2) After the soil thaws in spring, spread the mixture evenly on the surface of the acidic soil. The amount of mixture used is 10,000 kg·hm². - ², after plowing, rotary tillage to a depth of 25cm, and then sowing.

[0037] Example 2 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 20 parts coarse gasification slag, 10 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0038] Example 3 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 30 parts coarse gasification slag, 10 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0039] Example 4 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 40 parts coarse gasification slag, 10 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0040] Example 5 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 50 parts coarse gasification slag, 10 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0041] Example 6 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 60 parts coarse gasification slag, 10 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0042] Example 7 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 20 parts coarse gasification slag, 20 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0043] Example 8 The difference between this embodiment and Embodiment 1 is that: an acid soil conditioner based on coal-water slurry gasification slag includes the following components in parts by mass: 40 parts coarse gasification slag, 20 parts fine gasification slag, 3 parts bentonite, and 8 parts humus.

[0044] Comparative Example 1 The difference between this comparative example and Example 8 is that the fermentation method is different.

[0045] The method for preparing the humic substance includes the following steps: (1) Mix pigeon manure and chicken manure at a mass ratio of 1:2, add water, and obtain fermentation raw material with a water content of 52wt%; (2) Add 1% of Bacillus amyloliquefaciens and 0.5% of Bacillus subtilis by weight of the fermentation raw materials to the fermentation raw materials, mix them evenly, and carry out aerobic fermentation. The aerobic fermentation time is 18 days. When the internal temperature of the pile exceeds 50°C, turn it over immediately; if the threshold is not reached, turn it over once every 3 days. (3) Spread the fermented material to a thickness of 6cm, heat it to sterilize at 70℃, maintain a relative humidity of 65%, and sterilize for 30 minutes. After sterilization, cool it to room temperature to obtain humus.

[0046] Comparative Example 2 The difference between this comparative example and Example 8 is that the order of adding the microbial agents is different.

[0047] The method for preparing the humic substance includes the following steps: (1) Mix pigeon manure and chicken manure at a mass ratio of 1:2, add water, and obtain fermentation raw material with a water content of 52wt%; (2) Add 0.5% of Bacillus subtilis by weight to the fermentation raw material, mix evenly, and carry out the first aerobic fermentation. The first aerobic fermentation takes 6 days. When the internal temperature of the pile exceeds 50°C, turn it over immediately; if the threshold is not reached, turn it over once every 3 days.

[0048] (3) Continue to add 1% of Bacillus amyloliquefaciens by weight of fermentation raw materials, mix evenly, and carry out the second aerobic fermentation. The second aerobic fermentation time is 12 days. When the internal temperature of the pile exceeds 50℃, turn it over immediately; if the threshold is not reached, turn it over once every 3 days. (4) Spread the fermented material evenly to a thickness of 6cm, heat it to sterilize at 70℃, maintain a relative humidity of 65%, and sterilize for 30 minutes. After sterilization, cool it to room temperature to obtain humus.

[0049] Comparative Example 3 The difference between this comparative example and Example 8 is the amount of bacterial agent used.

[0050] The method for preparing the humic substance includes the following steps: (1) Mix pigeon manure and chicken manure at a mass ratio of 1:2, add water, and obtain fermentation raw material with a water content of 52wt%; (2) Add 0.5% of Bacillus amyloliquefaciens by weight to the fermentation raw material, mix evenly, and carry out the first aerobic fermentation. The first aerobic fermentation takes 6 days. When the internal temperature of the pile exceeds 50°C, turn it over immediately; if the threshold is not reached, turn it over once every 3 days.

[0051] (3) Continue to add 1% of Bacillus subtilis by weight of fermentation raw materials, mix evenly, and carry out the second aerobic fermentation. The second aerobic fermentation time is 12 days. When the internal temperature of the pile exceeds 50℃, turn it over immediately; if the threshold is not reached, turn it over once every 3 days. (4) Spread the fermented material evenly to a thickness of 6cm, heat it to sterilize at 70℃, maintain a relative humidity of 65%, and sterilize for 30 minutes. After sterilization, cool it to room temperature to obtain humus.

[0052] Comparative Example 4 The difference between this comparative example and Example 8 is that the type of bacterial agent is different.

[0053] Bacillus subtilis, catalog number Delf-28596, Hefei Wanwu Biotechnology Co., Ltd., live bacteria content: 100 billion CFU / g. Replaced with: Bacillus subtilis, catalog number: BNCC109047, live bacteria content: 100 billion CFU / g, Beina Chuanglian Biotechnology Co., Ltd.

[0054] Bacillus amyloliquefaciens, catalog number Delf-27787, Hefei Wanwu Biotechnology Co., Ltd., live bacteria content: 100 billion CFU / g, replaced by: Bacillus amyloliquefaciens, catalog number: BNCC336388, live bacteria content: 100 billion CFU / g, Beina Chuanglian Biotechnology Co., Ltd.

[0055] Comparative Example 5 The difference between this comparative example and Example 8 is that pigeon droppings are replaced with sheep droppings.

[0056] Comparative Example 6 This comparative example is the product of Example 1 of Chinese Patent CN118956409B, which describes an acidic soil conditioner, its preparation method, and its application.

[0057] Performance testing Experiments were conducted on typical acidic soil (0-50cm soil layer) in Heishan District, Yiyang City, Hunan Province. Soil conditioners from Examples 1-8 and Comparative Examples 1-6 were used for soil amendment, while the control group received no conditioner. Soil samples were collected after 50 days for analysis. The basic physicochemical properties of coal-water slurry gasification residue (obtained from Ordos Wushen Banner Boda Fertilizer Co., Ltd.) and the effects of the soil conditioners from Examples 1-8 on the physicochemical properties of acidic soil were analyzed. Experimental equipment included a laser particle size analyzer, a spatula, a wooden roller, and a 1mm sieve. The acidic soil conditioner experiment employed a three-factor, multi-level, nine-treatment orthogonal experimental design, with three replicates for each treatment.

[0058] Test methods (1) Soil particle size distribution was determined using a laser particle size analyzer: After the soil and gasification slag were air-dried, they were rolled through a 1mm sieve using a wooden roller. The sieved samples were then placed in a laser particle size analyzer for measurement. The data were processed using the Talwin particle size analysis software to determine the particle size distribution and soil texture. At the same time, physical parameters such as soil bulk density and porosity were measured. The results are shown in […]. Figure 1 .

[0059] pass Figure 1 It is evident that the addition of gasification slag is beneficial for improving soil structure and increasing soil nutrients. Electron microscopy revealed some spherical particles on the surface of the gasification slag, and its loose surface allows for a large specific surface area, resulting in good water permeability and retention capacity, as well as high potential adsorption capacity. This also helps improve soil pore structure, increase porosity and soil water holding capacity, thus improving soil structure. Therefore, solid waste significantly accelerates soil moisture transport, improves soil permeability, and is suitable for acid soil improvement.

[0060] (2) Test results of the physicochemical properties of acid soil Soil bulk density: The mass of a unit volume of undisturbed soil (including pores) after drying. The formula is as follows: ρb=Mdry soil÷Vundant soil, where: ρb: soil bulk density; Mdry soil: the mass of soil dried to constant weight at 105℃; Vundant soil: the volume of soil (including pores) that retains its natural structure at the time of sampling.

[0061] Particle size composition: Sand particles range from 2.0 to 0.05 mm (inclusive); powder particles range from 0.05 to 0.002 mm (inclusive); clay particles range from <0.002 mm.

[0062] Porosity: Total porosity Pt (%) = (1 - ρb ÷ ρp) × 100%. ρb: Soil bulk density, determined by the ring sampler method; ρp: Soil particle density, determined by the hydrostatic bottle method.

[0063] The results are shown in Table 1 and... Figure 2-3 .

[0064] Table 1. Test results of improved acidic soil properties

[0065] From Table 1 and Figure 2-3 It can be seen that, compared with the unmodified control group (CK), the physical structure of acidic soil was significantly improved after treatment with the modifier of the present invention.

[0066] Furthermore, it was found that Examples 6 and 8 exhibited superior overall performance, with Example 8 demonstrating the best overall performance. This is because the ratio of 40 parts coarse gasification slag to 20 parts fine gasification slag balances both pore size enhancement and adsorption / filling effects. Combined with 3 parts bentonite and 8 parts humus, the sand particle agglomeration, acid-base buffering, and fertilizer retention capacity achieve synergistic effects, making it more suitable for improving the structure of acidic soils than other ratios. This indicates that mixing two types of gasification slag with specific parameters in specific ratios with two other components results in a more significant synergistic effect, primarily manifested in a significant reduction in bulk density: as the proportion of gasification slag increases, the soil bulk density decreases systematically (P<0.05), effectively improving the compaction problem of acidic soils. Optimized particle size distribution: the sand content significantly increased (P<0.05), while the clay and silt content significantly decreased (P<0.05), gradually transforming the soil texture from the original silty loam to sandy loam, effectively reducing capillary action. Improved pore structure: Total porosity increased in a stepwise manner; both capillary porosity and non-capillary porosity were significantly improved (P<0.05), soil permeability was enhanced, and drainage capacity was greatly improved.

[0067] In Comparative Example 1, the mixed fermentation of microorganisms resulted in a decreased effectiveness of the soil conditioner. Analysis showed that Example 8 involved phased inoculation, first introducing *Bacillus amyloliquefaciens* to decompose easily degradable organic matter and establish a dominant microbial community, followed by the inoculation of *Bacillus subtilis* to degrade recalcitrant lignin / cellulose. In contrast, Comparative Example 1 involved a single-stage mixed fermentation, leading to substrate competition between the two microorganisms. This inhibited the early proliferation of *Bacillus amyloliquefaciens*, resulting in insufficient temperature rise in the compost pile, incomplete decomposition of manure by miscellaneous bacteria, a decrease in humic acid conversion rate, a significant reduction in the ability of humic material to bind sand particles, and the inability of low-quality humic material to effectively coat gasification slag particles. This hindered the release of alkaline components from the gasification slag, resulting in insufficient pH increase in the soil, and sand particle dispersion leading to increased bulk density and decreased porosity.

[0068] In Comparative Example 2, the altered fermentation sequence of the inoculant resulted in a decreased improvement in soil physicochemical properties. Analysis revealed a substrate mismatch during the fermentation initiation stage. The core function of Bacillus subtilis is to degrade recalcitrant organic matter, while the initial fermentation stage of manure primarily consists of easily degradable proteins and polysaccharides. Inoculating with Bacillus subtilis first leads to insufficient initial fermentation momentum, slow temperature rise in the compost pile, and ineffective suppression of other microorganisms. Later, when Bacillus amyloliquefaciens was introduced, most of the substrate had already been consumed, limiting its colonization and metabolic activity. The humic acid content and basic groups in the humic material were lower than in Example 8, resulting in reduced cross-linking and adsorption capacity between the prepared humic material and bentonite, hindering effective sand particle aggregation. Simultaneously, the slow-release synergistic effect on the alkaline components of the gasification slag was weakened, leading to a deterioration in soil pH and porosity.

[0069] In Comparative Example 3, the reduced dosage of Bacillus amyloliquefaciens prevented the rapid decomposition of easily degradable substrates, resulting in a large amount of residual miscellaneous bacteria, localized putrefaction of the fermentation material, and a significant decrease in the purity and activity of humic substances. While the dosage of Bacillus subtilis was increased, the amount of difficult-to-degrade substrates remained limited in the later stages. Excessive inoculum resulted in the death of many bacteria due to insufficient nutrients, and the production of metabolic organic acids lowered the pH of the humic substances. Simultaneously, the putrefied humic substances could not form a stable improvement system with bentonite and gasification slag, resulting in the worst sand agglomeration effect, the most significant increase in bulk density, and a small increase in soil pH.

[0070] Example 8 uses a bacterial agent with a specific strain number, which has a high colonization rate in pigeon manure and chicken manure substrates and a higher cellulase / protease activity ratio; in Comparative Example 4, the bacterial improvement index of strains with strain numbers from other manufacturers deteriorates.

[0071] In Comparative Example 5, replacing pigeon manure with sheep manure resulted in a decrease in the improvement performance. Analysis revealed that pigeon manure, being high in nitrogen and phosphorus, becomes slightly alkaline after composting; while sheep manure has a higher proportion of fiber, a slower composting rate, a lower humification coefficient than pigeon manure, and a slightly acidic pH after composting, indicating insufficient alkaline groups. Furthermore, the humic acid molecules in sheep manure-based humic materials are smaller, resulting in weaker cross-linking ability with bentonite compared to pigeon / chicken manure-based humic materials, leading to reduced sand particle aggregation. Additionally, its acid-base buffering capacity is insufficient, failing to fully synergize with the alkaline components of the gasification slag.

[0072] The acid soil conditioner provided by this invention can specifically solve the core problems of acid soil such as compact structure and poor drainage, improve extremely poor acid soil towards ideal loam, and realize the resource utilization of industrial waste, which has significant economic, ecological and social benefits.

[0073] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A soil conditioner based on coal-water slurry gasification slag, characterized in that, The components include the following parts by weight: 10-60 parts of coarse gasification slag, 0-20 parts of fine gasification slag, 1-10 parts of bentonite, and 1-15 parts of humus; the humus is obtained by first fermenting pigeon manure and chicken manure with Bacillus amyloliquefaciens, then adding Bacillus subtilis for fermentation, and sterilizing.

2. The acid soil conditioner based on coal-water slurry gasification slag according to claim 1, characterized in that, The components include the following parts by weight: 40-60 parts of coarse gasification slag, 10-20 parts of fine gasification slag, 1-5 parts of bentonite, and 5-10 parts of humus.

3. The acid soil conditioner based on coal-water slurry gasification slag according to claim 1, characterized in that, The method for preparing the humic substance includes the following steps: (1) Mix pigeon manure and chicken manure at a mass ratio of 1:(2-3), add water, and obtain fermentation raw materials; (2) Add Bacillus amyloliquefaciens to the fermentation raw materials, mix well, and carry out the first aerobic fermentation; (3) Continue to add Bacillus subtilis, mix well, and carry out the second aerobic fermentation; (4) After the fermented material is sterilized, it is cooled to room temperature to obtain humus.

4. The acid soil conditioner based on coal-water slurry gasification slag according to claim 3, characterized in that, The strain number of Bacillus subtilis is Delf-28596, and the strain number of Bacillus amyloliquefaciens is Delf-27787.

5. The acid soil conditioner based on coal-water slurry gasification slag according to claim 3, characterized in that, The mass ratio of Bacillus amyloliquefaciens to Bacillus subtilis is (1-2):(0.5-1).

6. The acid soil conditioner based on coal-water slurry gasification slag according to claim 1, characterized in that, The gasification coarse slag has a particle size of 4750-10000 μm and a bulk density of 0.86-0.89 g. cm - ³, saturated water content is 63-66%, and cation exchange capacity is 7.80-7.82 cmol·kg⁻¹. - ¹, the loss on ignition rate is 16-17%.

7. The acid soil conditioner based on coal-water slurry gasification slag according to claim 1, characterized in that, The gasification slag has a particle size <1000μm and a bulk density of 0.35-0.37g·cm³. - ³, saturated water content 224-225%, cation exchange capacity 3.87-3.89 cmol·kg⁻¹ - ¹, the loss on ignition rate is 28-30%.

8. The acid soil conditioner based on coal-water slurry gasification slag according to claim 1, characterized in that, The bentonite comprises the following components by mass percentage: 60%-75% SiO2, 12%-20% Al2O3, 3%-8% total CaO, MgO, Na2O and K2O, with the remainder being impurities.

9. A method for preparing an acid soil conditioner based on coal-water slurry gasification slag as described in any one of claims 1-8, characterized in that, The process includes the following steps: mixing all raw materials evenly to obtain an acid soil conditioner based on coal-water slurry gasification residue.

10. A method for improving acidic soil conditioner based on coal-water slurry gasification slag as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix 10-30 parts by weight of the amendment and 70-90 parts by weight of the acid soil to obtain a mixture; (2) Spread the mixture evenly on the surface of the acidic soil, plow and rotary till, and then sow.

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