Compound agent for improving acid soil as well as preparation method and application of compound agent

Abstract

The invention provides a compound agent for improving acid soil, a preparation method and application. The compound agent for improving the acid soil comprises calcium-magnesium-silicon-based mineral powder and silicate bacterial liquid, the solid-to-liquid ratio of the calcium-magnesium-silicon-based mineral powder to the silicate bacterial liquid is (0.5-1.0) g: (80-120) mL. The calcium-magnesium-silicon-based mineral powder and the silicate bacterial liquid can efficiently and enduringly neutralize the acidity of the soil through a synergistic mechanism of mineral slow release and biological activation, significantly increase the pH value of the soil, promote slow release and enrichment of nutrient elements such as calcium, magnesium, potassium and silicon, and effectively improve the physical and chemical properties of the soil. Moreover, the preparation method disclosed by the invention is simple, convenient to operate, low in cost and easy for large-scale production and application, and has important significance for realizing green and sustainable improvement of acid soil and safe production of vegetables.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, and particularly relates to compound agents, preparation methods and applications for improving acidic soils. Background Technology

[0002] In red soil regions, long-term cultivation and overuse of chemical fertilizers have led to increasingly serious soil acidification problems. Soil acidification not only lowers the soil pH value but also triggers a series of ecological chain reactions, such as increased aluminum toxicity, loss of basic ions, and fertility decline, severely restricting sustainable agricultural development. Soil acidification reduces the availability of nutrients, decreases land productivity, and seriously affects crop yield and quality. To improve arable land soil fertility and achieve sustainable agricultural development, it is essential to improve and restore acidic soils. In agricultural production, the application of soil conditioners is the most effective improvement measure.

[0003] Currently, the most common methods for improving acidic soils in agricultural production include adding lime-based amendments, organic materials, and calcium, magnesium, and silicon minerals. However, all of these methods have certain limitations. For example, while existing traditional lime-based amendments can raise soil pH, their effect is short-lived, leading to a decrease in calcium content. 2+ / Mg 2+ Imbalance affects soil structure and fertility. For example, while organic materials are effective in improving soil by increasing organic matter content and structure, the process of improving soil pH is lengthy. Calcium, magnesium, and silicon minerals primarily affect the soil surface layer, with limited effectiveness in improving acidity in the subsurface, resulting in persistent soil acidification in deeper layers and impacting crop root growth. Therefore, this invention provides a compound agent for improving acidic soils, its preparation method, and its application. Summary of the Invention

[0004] The main objective of this invention is to provide a compound agent for improving acidic soil, including the preparation method and application, aiming to solve the technical problem of poor soil improvement effect in the prior art.

[0005] To achieve the above objectives, the present invention provides a compound agent for improving acidic soil, the compound agent comprising calcium-magnesium-silica-based mineral powder and silicate bacterial solution.

[0006] The solid-liquid ratio of the calcium-magnesium-silica-based mineral powder and the silicate bacterial solution is (0.5~1.0)g:(80~120)mL.

[0007] According to embodiments of this application, the calcium-magnesium-silicon-based mineral powder includes two or more of metamorphic dolomite, black talc, and sandstone.

[0008] According to embodiments of this application, the silicate bacteria in the silicate bacterial solution include one or more of Bacillus colloidis, Bacillus bromide, and Bacillus sphaeroides.

[0009] According to an embodiment of this application, the optical density of the silicate bacterial solution at a wavelength of 600 nm is 0.6 to 1.0.

[0010] The present invention also provides a method for preparing the above-mentioned compound agent for improving acidic soil, comprising: The calcium-magnesium-silica-based mineral powder is mixed evenly with the silicate bacterial solution to obtain the compound agent for improving acidic soil.

[0011] According to an embodiment of this application, the method for obtaining the silicate bacterial solution includes: inoculating silicate bacteria into a liquid culture medium, shaking and culturing at 25-35°C and 150-200 r / min for 20-28 h, and stopping the culture when the optical density of the culture medium at a wavelength of 600 nm is 0.6-1.0, thereby obtaining the silicate bacterial solution.

[0012] Application of the compound agent for improving acidic soil as described above or the compound agent prepared by the above preparation method in improving acidic soil.

[0013] According to an embodiment of this application, the compound agent for improving acidic soil is applied to acidic soil with a pH value below 5.0.

[0014] The volume of the compound agent added to each kilogram of acidic soil is 200-1000 mL.

[0015] According to the embodiments of this application, the compound agent for improving acidic soil is applied 5 to 10 days before sowing or during the crop fallow period.

[0016] When the compound agent for improving acidic soil is applied, the soil moisture content is 40-60% of field capacity.

[0017] Application of the compound agent for improving acidic soil as described above, or the compound agent prepared by the above preparation method, in crop cultivation in acidic soil.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The aforementioned compound agent, preparation method, and application for improving acidic soils involve mixing calcium-magnesium-silica-based mineral powder and silicate bacterial solution in a defined ratio to obtain a compound agent capable of simultaneously and efficiently reducing acidity and replenishing nutrients. Specifically, the calcium-magnesium-silica-based mineral powder rapidly neutralizes soil acidity and increases soil pH. The microorganisms in the silicate bacterial solution, through bioactivation, decompose silicate minerals in the soil to continuously release nutrients, not only improving the improvement effect but also enhancing the soil's self-repair capacity. Through a synergistic mechanism of mineral slow release and bioactivation, the calcium-magnesium-silica-based mineral powder and silicate bacterial solution efficiently and persistently neutralize soil acidity, significantly increase soil pH, and promote the slow release and enrichment of nutrients such as calcium, magnesium, potassium, and silicon, effectively improving soil physicochemical properties. This ensures rapid improvement and long-term stability of soil acidity, achieving highly efficient improvement of acidic soils.

[0019] Moreover, the preparation method of the present invention is simple, easy to operate, low in cost, and easy to scale up for production and application, which is of great significance for realizing the green and sustainable improvement of acidic soil and the safe production of vegetables. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 The figures show the soil pH and exchangeable acidity of each experimental group in Example 1; where (a) is the pH figure and (b) is the exchangeable acidity figure. Figure 2 The graph shows the exchangeable calcium and exchangeable magnesium content in the soil of each experimental group in Example 1; where (a) represents exchangeable calcium and (b) represents exchangeable magnesium. Figure 3 The figures show the soil pH and exchangeable acidity of each experimental group in Example 2; where (a) is the pH figure and (b) is the exchangeable acidity figure. Figure 4 The graph shows the exchangeable calcium and exchangeable magnesium content in the soil of each experimental group in Example 2; where (a) represents exchangeable calcium and (b) represents exchangeable magnesium. Figure 5 The graph shows the contents of available potassium, available phosphorus, available silicon and organic matter in the soil of each experimental group in Example 3; where (a) is available potassium, (b) is available phosphorus, (c) is available silicon and (d) is organic matter. Figure 6The diagram shows the seed germination rate of each experimental group in Example 3; Figure 7 The plant height and root length of the seedlings obtained from the seeds of each experimental group in Example 3 are shown; where (a) is the root length and (b) is the plant height.

[0022] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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.

[0024] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] To achieve the above objectives, the present invention provides a compound agent for improving acidic soil, the compound agent comprising calcium-magnesium-silica-based mineral powder and silicate bacterial solution.

[0026] The solid-liquid ratio of the calcium-magnesium-silica-based mineral powder and the silicate bacterial solution is (0.5~1.0)g:(80~120)mL.

[0027] In some embodiments, calcium-magnesium-silica-based minerals serve as natural carriers of alkaline ions, while silicate bacteria are probiotics with potassium- and silicon-solubilizing functions. If the solid-liquid ratio of the calcium-magnesium-silica-based mineral powder to the silicate bacteria solution is too low, it is difficult to effectively activate sufficient mineral nutrients; if the solid-liquid ratio is too high, excessive bacterial count per unit area may lead to nutrient competition or accumulation of metabolites, thus inhibiting mineral dissolution efficiency. Therefore, the solid-liquid ratio of the calcium-magnesium-silica-based mineral powder to the silicate bacteria solution determined in this invention is (0.5~1.0) g : (80~120) mL, within which the microbial-mineral interface reaction achieves optimal efficiency.

[0028] In some embodiments, the calcium-magnesium-silicon-based mineral powder is rich in alkaline elements such as calcium (Ca), magnesium (Mg), and silicon (Si), which can quickly neutralize acidic substances in the soil and increase the soil pH. The microorganisms in the silicate bacterial solution can continuously decompose silicate minerals in the soil, releasing soluble nutrients such as potassium and phosphorus, providing a long-lasting buffering capacity and extending the duration of the soil amendment effect. The calcium-magnesium-silicon-based mineral powder gradually dissolves in the soil, releasing calcium... 2+ and Mg 2+ Ions can enhance soil particle aggregation, improve soil physical properties, prevent soil compaction, and increase soil aeration. Through the synergistic effect of calcium-magnesium-silicon-based mineral powders and silicate bacterial solutions, essential nutrients such as calcium, magnesium, silicon, potassium, and phosphorus can be replenished in the soil, improving soil fertility. Simultaneously, calcium and magnesium are essential micronutrients for plant growth, enhancing plant resistance to stress and improving crop quality. Silicon can enhance plant disease resistance and lodging resistance.

[0029] In some embodiments, the microorganisms in the silicate bacterial solution form a biofilm in the soil, which can continuously decompose calcium, magnesium, and silicon-based minerals and slowly release alkaline substances such as calcium, magnesium, silicon, and potassium to rapidly improve soil acidity and maintain the soil's acid-base balance for a relatively long period. It should be noted that silicate bacteria, through the secretion of metabolic products such as organic acids and extracellular polysaccharides, can disrupt the crystal structure of calcium, magnesium, and silicon minerals, accelerating the decomposition of calcium and magnesium-based minerals. 2+ Mg 2+ K + The release of plasma. These ions can neutralize H+ in the soil. + It can also provide essential nutrients for crops. At the same time, the silicon released from the dissolution of minerals can strengthen plant cell walls and improve stress resistance. This synergistic effect between microorganisms and minerals constitutes a virtuous cycle of "bio-minerals," which is the core mechanism of this invention for achieving simultaneous soil improvement and fertilization.

[0030] In some embodiments, calcium-magnesium-silica-based mineral powder is a high-quality secondary resource. Utilizing it for soil improvement can reduce industrial waste emissions and achieve resource recycling. This reduces environmental pollution and improves resource utilization efficiency. Silicate bacterial solution continuously releases nutrients through bioactivation, ensuring the stability of the improvement effect. It also reduces dependence on chemical fertilizers and lowers the risk of soil and water pollution. Through a synergistic mechanism based on "mineral slow release-bioactivation," the combination of calcium-magnesium-silica-based mineral powder and silicate bacterial solution can efficiently reduce acidity and replenish nutrients, exhibiting significant environmental friendliness and economic efficiency. It overcomes the shortcomings of single soil conditioners. The compound agent for improving acidic soils described in this invention can significantly improve soil pH balance and fertility, promote healthy plant growth, and has broad application prospects.

[0031] The aforementioned compound agent for improving acidic soils is obtained by mixing calcium-magnesium-silica-based mineral powder and silicate bacterial solution in a defined ratio. This compound agent can simultaneously and efficiently reduce acidity and replenish nutrients in acidic soils. The calcium-magnesium-silica-based mineral powder can rapidly neutralize soil acidity and increase soil pH. The microorganisms in the silicate bacterial solution, through bioactivation, decompose silicate minerals in the soil to continuously release nutrients, not only improving the improvement effect but also enhancing the soil's self-repair capacity. Through a synergistic mechanism of mineral slow release and bioactivation, the calcium-magnesium-silica-based mineral powder and silicate bacterial solution can efficiently and persistently neutralize soil acidity, significantly increase soil pH, and promote the slow release and enrichment of nutrients such as calcium, magnesium, potassium, and silicon, effectively improving soil physicochemical properties. This ensures rapid improvement and long-term stability of soil acidity, achieving highly efficient improvement of acidic soils.

[0032] In some embodiments, the calcium-magnesium-silicon-based mineral powder includes two or more of metamorphic dolomite, black talc, and sandstone.

[0033] In some embodiments, the main component of metamorphic dolomite is dolomite (CaMg(CO3)2), which contains high levels of calcium (Ca) and magnesium (Mg). The calcium and magnesium ions in metamorphic dolomite can rapidly neutralize acidic substances in the soil, raising the soil pH. Furthermore, calcium and magnesium ions can promote soil particle aggregation, improve soil physical properties, and increase soil aeration and water retention capacity. Metamorphic dolomite gradually dissolves in the soil, providing a lasting acid neutralization effect and reducing the rebound of soil acidification.

[0034] In some embodiments, the main component of black talc is talc (Mg3Si4O). 10 (OH)2 contains high levels of magnesium (Mg) and silicon (Si), which help neutralize soil acidity and provide nutrients. Among these, magnesium is an important secondary element required for plant growth, while silicon can enhance the plant's disease resistance and lodging resistance.

[0035] In some embodiments, the main components of sandstone are quartz (SiO2) and feldspar (KAlSi3O8), with high silicon (Si) and potassium (K) content. The silicate minerals in sandstone can neutralize acidic substances in the soil, increase the soil pH, and replenish silicon and potassium, thereby improving crop yield and quality.

[0036] In some embodiments, the calcium-magnesium-silicon-based mineral powder is metamorphic dolomite and sandstone. The mass ratio of the metamorphic dolomite to sandstone is 1:1 to 1:2. Excessive metamorphic dolomite content can lead to over-alkalization.

[0037] In some embodiments, the silicate bacteria in the silicate bacterial solution include one or more of Bacillus colloidis, Bacillus bromide, and Bacillus sphaeroides.

[0038] In some embodiments, Bacillus subtilis, Bacillus bromide, and Bacillus spp. can decompose silicates and aluminosilicates, releasing nutrients such as potassium and phosphorus. These strains also improve soil fertility by secreting organic acids and enzymes to convert insoluble silicate minerals into forms that can be absorbed by plants.

[0039] In some other embodiments, the viable bacterial count concentration of the silicate bacterial solution is 1 × 10⁻⁶. 8 ~5×10 9 CFU / mL. Controlling the viable bacteria concentration in silicate bacterial solutions ensures sufficient biological activity in the soil for the continuous and effective decomposition of silicate minerals, providing a sustained nutrient supply and reducing plant growth limitations caused by nutrient deficiency. Furthermore, high concentrations of viable bacteria can secrete large amounts of plant growth hormones, promoting seed germination and root development, thereby increasing crop yield and quality.

[0040] The present invention also provides a method for preparing a compound agent for improving acidic soil as described above, comprising: mixing calcium magnesium silicate mineral powder with silicate bacterial solution evenly to obtain the compound agent for improving acidic soil.

[0041] In some embodiments, by mixing two or more of metamorphic dolomite, black talc, and sandstone, mechanically pulverizing the mixture, and then passing it through a 100-mesh sieve, the resulting small-particle-size powder is the calcium-magnesium-silicon-based mineral powder.

[0042] In some implementations, mixing calcium-magnesium-silica-based mineral powder with silicate bacterial solution in a specific ratio can effectively neutralize acidic substances in the soil, gradually raising the pH value of acidic soil to near neutral or a range suitable for plant growth. This creates a more suitable growth environment for plant roots, preventing problems such as stunted growth and poor nutrient absorption caused by excessively acidic soil. The calcium-magnesium-silica-based mineral powder continuously releases alkaline components such as calcium, magnesium, and silicon into the soil. Its synergistic effect with the silicate bacterial solution helps maintain the relative stability of soil pH, thus preserving the soil's good physical and chemical properties for a longer period and ensuring long-term plant growth.

[0043] In some embodiments, the addition of calcium-magnesium-silica-based mineral powder can increase the connection and aggregation between soil particles, resulting in a well-structured aggregate structure. This improves soil aeration, permeability, and water retention, making the soil looser, reducing soil compaction, and promoting root extension and growth. It also provides favorable spatial conditions for soil microbial activity. During their reproduction and metabolism in the soil, the microorganisms in the silicate bacterial solution can decompose organic matter and minerals, converting some insoluble nutrients into forms that plants can absorb and utilize. For example, they release elements such as phosphorus and potassium from insoluble phosphates and potassium feldspar, increasing nutrient availability and further promoting nutrient absorption and utilization by plants, thus achieving a virtuous cycle of soil nutrients.

[0044] The raw materials for preparing the compound agent described in this invention are mainly inexpensive natural calcium, magnesium, and silicon-based minerals and beneficial microorganisms, which aligns with the concepts of green agriculture and sustainable development. Furthermore, it can be prepared in batches and has strong applicability.

[0045] In some embodiments, the silicate bacterial solution is obtained by inoculating silicate bacteria into a liquid culture medium and culturing it with shaking at 25-35°C and 150-200 r / min. When the optical density of the culture medium at a wavelength of 600 nm is 0.6-1.0, the culture is stopped.

[0046] In some embodiments, controlling the temperature of silicate bacteria inoculated into the liquid culture medium helps maintain the activity and stability of the bacteria, avoiding bacterial mutations or death that may occur due to high temperatures, thereby ensuring the quality and effectiveness of the silicate bacterial solution. Furthermore, silicate bacteria cultured under low-temperature conditions exhibit stronger environmental adaptability. When these bacteria are applied to soil, they can survive and function under different soil temperature and humidity conditions, especially in soils with low temperatures or harsh environmental conditions, where they maintain good activity, thus making them more widely applicable to the improvement of various acidic soils. Optical density values ​​reflect the concentration and growth status of the bacteria in the culture medium. Quantitative detection ensures that each prepared silicate bacterial solution has a stable viable cell concentration, thereby guaranteeing the consistency of the compound's quality and effectiveness. Strict control of culture conditions and detection indicators ensures that the bacteria in the silicate bacterial solution have high activity and metabolic capacity. After these active bacteria enter the soil, they can more effectively decompose minerals and organic matter in the soil, releasing more nutrients and further improving soil fertility and improvement effects.

[0047] In some embodiments, the duration of the oscillation culture is 20-28 hours.

[0048] In some embodiments, adjusting the duration of shaking culture provides sufficient time for silicate bacteria to grow and reproduce, allowing them to reach a suitable growth state and ensuring optimal metabolic activity.

[0049] Application of the compound agent for improving acidic soil as described above or the compound agent prepared by the above preparation method in improving acidic soil.

[0050] In some embodiments, the compound agent for improving acidic soil is applied in agricultural planting. It is suitable for various crop planting areas, especially farmland where soil acidification has occurred due to long-term use of chemical fertilizers or natural factors. By using the compound agent described in this invention, soil pH can be effectively improved, soil fertility enhanced, healthy crop growth promoted, yield increased, and quality improved.

[0051] In some embodiments, the compound agent for improving acidic soil is used in Chinese cabbage cultivation and acidic soil improvement.

[0052] In some embodiments, the compound agent for improving acidic soil is applied to acidic soil with a pH value below 5.0.

[0053] The volume of the compound agent added to each kilogram of acidic soil is 200-1000 mL.

[0054] In some embodiments, the compound agent for improving acidic soil is applied to acidic soil with a pH of 4.0 to 5.0.

[0055] In some embodiments, the compound agent for improving acidic soil is applied to acidic soil with a pH of 4.5. By using the compound agent, the soil pH can be effectively improved, making it closer to neutral, thereby creating a suitable environment for plant growth.

[0056] In some embodiments, the volume of the compound agent for acidic soil added per kilogram of acidic soil can be appropriately adjusted according to the degree of soil acidification and the growth needs of plants, as long as it can ensure that the compound agent is evenly distributed in the soil and achieves the best effect.

[0057] In some embodiments, the compound agent is added to the tilled acidic soil. The volume of the compound agent added is 1000 mL per kilogram of acidic soil, followed by further tilling to obtain planting soil. Finally, the selected and disinfected cabbage seeds are evenly sown into the planting soil. Alternatively, base fertilizer is added to the planting soil, mixed thoroughly to obtain compound soil, and the selected and disinfected cabbage seeds are evenly sown into the compound soil. The base fertilizer is an inorganic compound fertilizer containing two or more major nutrients (nitrogen, phosphorus, and potassium). Tilling before planting helps improve soil structure and increase soil aeration, providing a physical channel for the penetration of the compound agent. Tilling after applying the compound agent helps to evenly mix the fertilizer spread on the surface into the entire cultivated layer, ensuring the uniformity of the applied compound agent. This application method is simple, easy to operate, saves a lot of manpower and resources, and is low in cost.

[0058] In some embodiments, the co-cultivation time after the compound agent is added to acidic soil is 5 to 20 days.

[0059] In some embodiments, the co-cultivation time after the compound agent is added to acidic soil is 7 to 15 days.

[0060] In some embodiments, the co-cultivation time after the compound agent is added to acidic soil is 15 to 20 days.

[0061] In some embodiments, the compound agent for improving acidic soil is applied 5 to 10 days before sowing or during the crop fallow period.

[0062] When the compound agent for improving acidic soil is applied, the soil moisture content is 40-60% of field capacity.

[0063] In some embodiments, applying the compound agent before sowing can provide sufficient time for microbial and mineral reactions, establishing a suitable rhizosphere microenvironment for crop (such as cabbage) growth.

[0064] In some embodiments, appropriate soil moisture needs to be maintained after the application of the compound agent. Specifically, soil moisture below 40% of field capacity will inhibit microbial activity and affect mineral dissolution efficiency; above 60% may lead to poor aeration and affect root development. Therefore, after applying the compound agent for improving acidic soil, the soil moisture should be controlled at 40-60% of field capacity.

[0065] Application of the compound agent for improving acidic soil as described above, or the compound agent prepared by the above preparation method, in crop cultivation in acidic soil.

[0066] To further illustrate the present invention, the following examples are provided: The silicate bacteria used in the examples were *Paenibacillus mucilaginosus*, purchased from the China General Microbiological Culture Collection Center (culture number: BNCC335819). The calcium-magnesium-silica-based minerals were metamorphic dolomite and sandstone. The main components of the metamorphic dolomite were CaO and MgO, and the sandstone was collected from Yunan County, Yunfu City, Guangdong Province, with the main components being SiO2, Al2O3, CaO, and K2O. The pH measurement data in the examples followed the national standard method for soil pH determination.

[0067] Example 1 Shake-flask experiments were conducted using acidic farmland soil from Yunan County, Guangdong Province. 50g of naturally dried soil was placed in a 250ml conical flask with an initial pH of 4.5.

[0068] A compound agent for improving acidic soil, prepared from calcium, magnesium, and silicon minerals and silicate bacterial solution, was mixed with soil and placed in an Erlenmeyer flask. The mixture was then incubated in a constant-temperature shaker for 15 days. After incubation, soil samples were taken to measure soil acidity. The optical density of the silicate bacterial solution at 600 nm was 0.8.

[0069] In Example 1, a total of 8 groups of experiments were conducted. The amount of substances added to each group is shown in Table 1, and the groups are numbered CK, B, S, B+J, S+J, B1S2+J, B1S1+J, and B2S1+J. Each group was repeated 3 times, and the average value of the experimental results was taken. The CK group served as the control group, with 0 added minerals and silicate bacterial solution. Except for the different amounts of silicate bacterial solution and minerals added, the other experimental conditions during the cultivation process were kept the same for each group.

[0070] Table 1. Amounts of substances added to each experimental group in Example 1 in, Figure 1 The diagram shows the soil pH and exchangeable acidity of each experimental group in Example 1; where, Figure 1 (a) is a pH graph. Figure 1 (b) is the exchangeable acidity diagram. From Figure 1The results show that adding sandstone alone (Group S) and the control group (CK) had similar effects on improving the pH of acidic soil. Even with the addition of silicate bacteria solution (Group S+J), the pH improvement effect was still poor. Adding metamorphic dolomite alone (Group B) and adding both metamorphic dolomite and silicate bacteria solution (Group B+J) significantly increased soil pH, but raised it to 7.58 and 7.79 respectively, posing a risk of soil over-alkalization. Generally, a pH exceeding 7.5 can lead to soil over-alkalization. In contrast, adding the same silicate bacteria solution but different masses of metamorphic dolomite and sandstone (Groups B1S2+J and B1S1+J) stabilized the soil pH to 6.58 and 7.26 respectively, improving the acidic soil to a range suitable for crop growth and effectively avoiding excessive alkalization.

[0071] Combined with the data on exchangeable acidity, it can be seen that the addition of metamorphic dolomite, metamorphic dolomite and silicate bacteria solution, sandstone and silicate bacteria solution, and metamorphic dolomite, sandstone and silicate bacteria solution can all significantly reduce soil exchangeable acidity. This reduces the number of free hydrogen ions in the soil, weakens soil acidity, increases pH value, and provides a stable soil pH for plant growth.

[0072] Exchangeable calcium and exchangeable magnesium are the core components that constitute soil "base saturation". The higher the content of these two ions, the stronger the soil's ability to buffer acid and the more stable the pH value. Figure 2 The graph shows the soil exchangeable calcium and exchangeable magnesium contents of each experimental group in Example 1; where, Figure 2 (a) is exchangeable calcium. Figure 2 (b) is exchangeable magnesium. From Figure 2 The results show that the exchangeable calcium and magnesium contents of group B+J are higher than those of group B, and the exchangeable calcium and magnesium contents of group S+J are higher than those of group S. This indicates a synergistic effect between silicate bacteria and minerals, which can promote the dissolution of calcium and magnesium ions from the minerals.

[0073] Example 2 A pot experiment was conducted using acidic farmland soil from Yunan County, Guangdong Province. 1 kg of naturally dried soil was used in each pot, with an initial soil pH of 4.5.

[0074] A compound agent for improving acidic soil, prepared from calcium, magnesium, and silicon minerals and silicate bacterial solution, was mixed with soil and placed in a container. An appropriate amount of deionized water was added, and the soil moisture was maintained at 40%–50% field capacity. The mixture was incubated at room temperature for 15 days. After incubation, soil acidity and nutrient indicators were measured. The optical density of the silicate bacterial solution at a wavelength of 600 nm was 0.8.

[0075] In Example 2, a total of 5 groups of experiments were conducted. The amount of substances added to each group is shown in Table 2, and the groups are numbered CK, B, B1S2+J, B1S1+J, and B2S1+J. Each group was repeated 3 times, and the average value of the experimental results was taken. The CK group served as the control group, and the amount of minerals and silicate bacterial solution added was 0. Except for the difference in the amount of silicate bacterial solution and minerals added, the other experimental conditions during the cultivation process were kept the same for each group.

[0076] Table 2. Amounts of substances added to each experimental group in Example 2 Figure 3 The diagram shows the soil pH and exchangeable acidity of each experimental group in Example 2; where, Figure 3 (a) is a pH graph. Figure 3 (b) is the exchangeable acidity diagram. From Figure 3 As can be seen, the soil pH of the control group (4.66) was strongly acidic. The addition of metamorphic dolomite alone (Group B), and the addition of metamorphic dolomite, sandstone, and silicate bacterial solution all showed significant improvement effects. Specifically, the soil pH of Groups B, B1S2+J, B1S1+J, and B2S1+J steadily increased to 6.95, 6.50, 6.74, and 6.85, respectively, thus improving the acidic soil to a range suitable for crop growth. Furthermore, the exchangeable acidity diagram shows that Groups B1S2+J, B1S1+J, and B2S1+J also significantly reduced the soil exchangeable acidity, lowering it to 0.121 cmol. + / kg, 0.417 cmol + / kg and 0.438 cmol + / kg. Figure 4 The graph shows the soil exchangeable calcium and exchangeable magnesium contents of each experimental group in Example 2; where, Figure 4 (a) is exchangeable calcium. Figure 4 (b) is exchangeable magnesium. From Figure 4 As can be seen, compared with the control group, the exchangeable calcium and magnesium contents of groups B, B1S2+J, B1S1+J and B2S1+J were significantly increased, indicating that the addition of minerals and silicate bacteria can effectively promote the enrichment of soil basic ions.

[0077] Available phosphorus, available potassium, and available silicon in soil are key indicators for evaluating soil nutrient availability, and their content directly affects crop nutrient supply and growth. Figure 5 The graph shows the content of available potassium, available phosphorus, available silicon, and organic matter in the soil of each experimental group in Example 3; among them, Figure 5 (a) is fast-acting potassium. Figure 5 (b) is fast-acting phosphorus. Figure 5 (c) is effective silicon. Figure 5 (d) is organic matter. From Figure 5 As can be seen, the contents of available phosphorus, available potassium, and available silicon in the soils corresponding to groups B1S2+J, B1S1+J, and B2S1+J were all significantly higher than those in group B and the control group. This indicates that silicate bacteria can significantly improve soil nutrient availability by decomposing mineral lattices and synergistically promoting the release and activation of nutrients such as phosphorus, potassium, and silicon. Although the addition of minerals and silicate bacteria solution did not significantly increase soil organic matter content, group B1S2+J also showed some effect. This further demonstrates that adding the aforementioned compound agent to acidic soil is not only effective in reducing acidity but also effectively fertilizes the soil.

[0078] Example 3 A pot experiment was conducted using acidic farmland soil from Yunan County, Guangdong Province. 1 kg of naturally dried soil was used in each pot, with an initial soil pH of 4.5.

[0079] A compound agent for improving acidic soil, prepared from calcium, magnesium, and silicon minerals and silicate bacterial solution, was mixed with soil and placed in pots. An appropriate amount of deionized water was added, and the soil moisture was maintained at 40%–50% field capacity. The mixture was incubated at room temperature for 7 days. After incubation, 10 selected and sterilized Chinese cabbage seeds were sown in each pot. Seed germination rate, plant height, and plant length were tested and recorded. The optical density of the silicate bacterial solution at 600 nm was 0.8.

[0080] In Example 3, four groups of experiments were conducted. The amount of substances added to each group is shown in Table 3, and the groups are numbered CK, B1S2+J, B1S1+J, and B2S1+J. Each group was repeated three times, and the average value of the results was taken. The CK group served as the control group, with zero addition of minerals and silicate bacterial solution. Except for the amount of silicate bacterial solution and minerals added, all other experimental conditions during the cultivation process remained the same for each group.

[0081] Table 3. Amounts of substances added to each experimental group in Example 3 Three days after sowing, the number of seedlings in each experimental group in Example 3 was counted, and the seed germination rate was calculated by the ratio of the number of seedlings to the number of seeds sown. Figure 6 This is a graph showing the seed germination rate of each experimental group in Example 3. From... Figure 6 It can be seen that the seed germination rate of the control group was only 40%, while the seed germination rates of the B1S2+J group, B1S1+J group, and B2S1+J group were 80%, 90%, and 90%, respectively. Seven days after sowing, the plant height and root length of the cabbage seedlings in each experimental group in Example 3 were measured and statistically analyzed. Figure 7 The plant height and root length of seedlings obtained from the seeds of each experimental group in Example 3; wherein, Figure 7(a) is the root length. Figure 7 (b) is the plant height. From Figure 7 As can be seen, the average plant height in the control group was 2.87 cm, and the average root length was 2.67 cm. The soil with the added compound agent significantly promoted the growth of cabbage seedlings. Specifically, the average plant height in the B1S1+J group was 9.87 cm, and the average root length was 3.8 cm, significantly increasing plant height and root length compared to the control group, thus promoting crop growth.

[0082] The compound agent for improving acidic soil described in this invention is obtained by mixing calcium-magnesium-silica-based mineral powder and silicate bacterial solution in a defined ratio. This results in a compound agent that can simultaneously and efficiently reduce acidity and replenish nutrients in acidic soil. The calcium-magnesium-silica-based mineral powder can rapidly neutralize soil acidity and increase soil pH. Microorganisms in the silicate bacterial solution, through bioactivation, decompose silicate minerals in the soil to continuously release nutrients, not only improving the improvement effect but also enhancing the soil's self-repair capacity. Through a synergistic mechanism of mineral slow release and bioactivation, the calcium-magnesium-silica-based mineral powder and silicate bacterial solution can efficiently and persistently neutralize soil acidity, significantly increase soil pH, and promote the slow release and enrichment of nutrients such as calcium, magnesium, potassium, and silicon, effectively improving soil physicochemical properties. This ensures rapid improvement and long-term stability of soil acidity, achieving highly efficient improvement of acidic soil.

[0083] Moreover, the preparation method of the present invention is simple, easy to operate, low in cost, and easy to scale up for production and application, which is of great significance for realizing the green and sustainable improvement of acidic soil and the safe production of vegetables.

[0084] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A compound agent for improving acidic soil, characterized in that, The compound agent for improving acidic soil includes calcium-magnesium-silica-based mineral powder and silicate bacterial solution; The solid-liquid ratio of the calcium magnesium silicate mineral powder and the silicate bacterial solution is (0.5~1.0)g:(80~120)mL.

2. The compound agent for improving acidic soil according to claim 1, characterized in that, The calcium-magnesium-silicon-based mineral powder includes two or more of metamorphic dolomite, black talc, and sandstone.

3. The compound agent for improving acidic soil according to claim 1, characterized in that, The silicate bacteria in the silicate bacterial solution include one or more of Bacillus colloidis, Bacillus blocculus, and Bacillus sphaeroides.

4. The compound agent for improving acidic soil according to claim 1, characterized in that, The optical density of the silicate bacterial solution at a wavelength of 600 nm is 0.6~1.

0.

5. A method for preparing a compound agent for improving acidic soil as described in any one of claims 1 to 4, characterized in that, include: The calcium-magnesium-silica-based mineral powder is mixed evenly with the silicate bacterial solution to obtain the compound agent for improving acidic soil.

6. The method for preparing the compound agent for improving acidic soil according to claim 5, characterized in that, The method for obtaining the silicate bacterial solution includes: inoculating silicate bacteria into a liquid culture medium, shaking and culturing at 25-35℃ and 150-200 r / min for 20-28 h, and stopping the culture when the optical density of the culture medium at a wavelength of 600 nm is 0.6-1.0, thereby obtaining the silicate bacterial solution.

7. The application of a compound agent for improving acidic soil as described in any one of claims 1 to 4, or a compound agent prepared by the preparation method as described in any one of claims 5 to 6, in improving acidic soil.

8. The application of the compound agent for improving acidic soil according to claim 7, characterized in that, The compound agent for improving acidic soil is applied to acidic soil with a pH value below 5.0; The volume of the compound agent added to each kilogram of acidic soil is 200-1000 mL.

9. The application of the compound agent for improving acidic soil according to claim 7, characterized in that, The compound agent for improving acidic soil is to be applied 5-10 days before sowing or during the crop fallow period. When the compound agent for improving acidic soil is applied, the soil moisture content is 40-60% of field capacity.

10. The application of a compound agent for improving acidic soil as described in any one of claims 1 to 4, or a compound agent prepared by the preparation method as described in any one of claims 5 to 6, in crop cultivation in acidic soil.

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