A method for improving soil acidification of Northeast black soil

Abstract

The present invention relates to the field of agricultural planting technology, specifically a method for improving soil acidification in Northeast China's black soil. The method achieves efficient and long-lasting soil remediation through the synergistic effects of targeted application of humic acid-calcium complexes, activation of microbial agents, and green manure planting. The technical solution includes: soil zoning, dividing the first acidification zone and the second acidification zone according to pH value, differentially applying humic acid-calcium complexes, and utilizing pH-responsive release of #imgabs0# to neutralize #imgabs1# and passivate #imgabs2#. Strip application of fungal agents to transport #imgabs3# to the root system through the mycelial network to improve calcium utilization. Soybean sowing, combined with citric acid spraying, activates mineral calcium through root secretions and increases organic matter input. Humic acid-calcium complexes are preferentially precipitated in the acidification zone. Mycelium-root systems synergistically construct an acidification-resistant microecology to increase crop yields. The method is suitable for the rapid remediation and sustainable management of moderately to severely acidified soils in Northeast China's black soil region.

Description

Technical Field

[0001] The present invention relates to the field of agricultural planting technology, and in particular to a method for improving the acidification of black soil in Northeast China. Background Art

[0002] As a key commercial grain base in my country, the Northeast Black Soil Region, with its fertile soil, nurtures a rich crop resource, playing an irreplaceable role in ensuring national food security. However, in recent years, this region has been facing the problem of acidification. Long-standing irrational agricultural production practices, such as excessive use of chemical fertilizers and a monoculture pattern, have disrupted the soil's acid-base balance and gradually increased soil acidity. Acidified black soil undergoes significant changes in its physical, chemical, and biological properties, resulting in a decline in soil fertility, a breakdown in aggregate structure, and a weakening of its ability to retain water and fertilizer, severely impacting the growth and development of crops.

[0003] In the past, traditional amelioration methods, such as the application of alkaline substances like lime, were primarily used to address soil acidification. While these methods can neutralize soil acidity and increase soil pH to a certain extent, they suffer from numerous drawbacks. For one thing, substances like lime have a relatively limited function, simply adjusting soil pH and failing to fundamentally improve the soil's ecological environment and fertility. Furthermore, traditional methods lack precision, making it difficult to effectively target hotspots of soil acidification. These methods are often applied blindly over large areas, resulting in a waste of resources and potentially negatively impacting soil ecosystems. Furthermore, the effects of traditional methods are short-lived; over time and with continued agricultural production, soil acidity can easily rise again, making long-term control of soil acidification difficult. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] The present invention aims to solve the technical problem in existing technologies of how to effectively treat hotspots of soil acidification on the basis of improving the ecological environment and fertility of the soil, and to ensure that the treatment results are long-term and effective.

[0006] (2) Technical solution

[0007] To this end, the present invention relates to a method for improving soil acidification of Northeast China black soil, comprising:

[0008] Dividing the target soil into the first acidification zone and the second acidification zone according to the parameters of the target soil;

[0009] Differential application of humic acid-calcium complex in target soils;

[0010] Apply the microbial inoculant strips to the target soil;

[0011] Sow soybean seeds into target soil.

[0012] Furthermore, the improved method includes: measuring parameters of the target soil, classifying a region of the target soil with a pH < 5.0 as a first acidification zone, and classifying a region with a pH of 5.0-5.5 as a second acidification zone;

[0013] Apply humic acid-calcium complex at 2-3 tons / ha in the first acidification zone of the target soil and 1.5-2 tons / ha in the second acidification zone;

[0014] Apply microbial inoculant strips to the target soil at a rate of 150-250 kg / ha;

[0015] Sow soybean seeds at a rate of 25-35 kg / ha into the target soil.

[0016] Furthermore, the preparation steps of the humic acid-calcium complex include:

[0017] Mix humic acid and calcium gluconate at a molar ratio of 1: (1.5-2.5) and dissolve in deionized water at a solid-liquid mass ratio of 1: (6-8);

[0018] Perform ultrasonic chelation on deionized water, control the temperature at 40-50°C, the power at 250-35W, the frequency at 30-40kHz, control the pH at 5.5-6.0, and perform ultrasonic chelation for 25-35 minutes to obtain a chelate solution;

[0019] The chelating liquid and biochar were mixed and shaken in a volume ratio of (3-5):1 and then vacuum dried to obtain a humic acid-calcium complex.

[0020] Furthermore, the preparation steps of the microbial agent include:

[0021] Add malic acid to a humic acid solution with a concentration of 0.08%-0.1% and a pH of 6-6.5;

[0022] The spores are mixed and cultured with a humic acid solution to obtain an activated spore solution;

[0023] After incubation, the activated spore solution is mixed with sterilized bentonite at a volume ratio of 1:(3-4) to obtain a spore suspension;

[0024] Add 2%-3% sodium alginate to the spore suspension and drop 2%-3% The solution is solidified, embedded in microcapsules and then dried to obtain the microbial agent.

[0025] Furthermore, after the soybeans grow, a citric acid solution is sprayed on the leaves.

[0026] Furthermore, after sowing the soybean seeds, auxiliary watering is performed and trehalose is added to the water to enhance the metabolic activity of the mycelium.

[0027] Furthermore, the target soil parameters include: pH, exchangeability , organic matter content.

[0028] Furthermore, the size of the biochar mesopores is 2-50 nm.

[0029] Furthermore, before applying the microbial agent, the soil parameters are measured. If the pH of the first acidified zone is less than 4.8, lime is applied at a rate of 0.3-0.5 tons / hectare to raise the pH to 4.8-5.0. After 6-8 days, the microbial agent is applied.

[0030] (3) Beneficial effects

[0031] The beneficial effects of the present invention are: the present invention mentions a method for improving the acidification of black soil in Northeast China, comprising: dividing the target soil into a first acidification zone and a second acidification zone according to the parameters of the target soil; differentially applying a humic acid-calcium complex to the target soil; applying microbial agent strips to the target soil; and sowing soybean seeds to the target soil.

[0032] The present invention achieves efficient repair of the acidification problem of Northeast China black soil by constructing an intelligent improvement system with humic acid as an ion transport promoter. By establishing a targeted migration mechanism, the humic acid-calcium complex accurately locates the acidification hotspot through the dual effects of carboxyl protonation precipitation in the low pH zone and soil micro-domain electric field guidance. Citric acid is used to activate the complex to release The mycelial network builds a "biological ion channel" to form a three-dimensional synergy of roots, mycelium and humic acid. The slow release increases the pH by 1.5 units, with a fluctuation of less than ±0.2. This application combines rapid response with sustained stability. In the black soil region of Jilin Province, it has achieved a 37% increase in corn yield and a 91% aluminum toxicity elimination rate, providing a new approach to soil acidification management. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a method for acidification and improvement of Northeast black soil mentioned in this application. DETAILED DESCRIPTION

[0034] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0035] refer to Figure 1 This application mentions a method for improving the acidification of black soil in Northeast China, comprising:

[0036] Step S100: Classify the target soil into a first acidification zone and a second acidification zone.

[0037] First, the parameters of the target soil were measured, and the area with a pH value less than 5.0 in the target soil was classified as the first acidification zone, and the area with a pH value of 5.0-5.5 was classified as the second acidification zone.

[0038] Among them, the parameters of the target soil include: pH, exchangeability , organic matter content.

[0039] For example, in the first acidification zone (pH < 5.0), the exchange >2cmol / kg, organic matter <2.5%, crop root development is hindered. The key to its improvement is to quickly neutralize active acid ions, such as 、 , and then rebuild the calcium store.

[0040] In the second acidification zone (pH: 5.0-5.5), there is a potential risk of acidification and a decrease in buffering capacity. The key improvement is to stabilize the pH value and enhance microbial activity.

[0041] Step S200: applying humic acid-calcium complex at 2-3 tons / hectare in the first acidification zone of the target soil, and applying humic acid-calcium complex at 1.5-2 tons / hectare in the second acidification zone.

[0042] In the low pH region, i.e. the first acidification region, carboxyl protonation and selective precipitation occur. The concentration is high. The carboxyl groups in the humic acid-calcium complex It has strong nucleophilicity and will react with the Protonation reaction occurs, destroying Chelate bond, i.e. Combine The carboxyl group is converted to -COOH. The protonation of the carboxyl group changes the polarity of the humic acid-calcium complex, and the intermolecular interactions also change accordingly. The complex, which originally had good water solubility due to the ionization of the carboxyl group, has a reduced solubility after protonation.

[0043] Selective precipitation allows the humic acid-calcium complex to be preferentially enriched in the acidified area. When the complex is precipitated in the acidified area, the dissociated humic acid (-COOH) is re-adsorbed. , forming HA-Al complexes, passivating aluminum toxicity, thereby improving soil acidification. At the same time, the precipitated complexes can also improve the physical structure of the soil, increase soil aggregation and porosity, and promote soil ventilation and water infiltration.

[0044] In a low pH environment, the quinone group (C=O) in humic acid has strong oxidizing properties and will accept electrons to be reduced to hydroquinone (-OH). The quinone group takes electrons from the surrounding environment and consumes the solution. The chemical reaction can be simply expressed as: The reduction of quinone groups results in electron transfer, which creates an electron gradient, manifesting as a redox potential difference. Microorganisms can use this electron gradient to respire and obtain energy.

[0045] In the second acidification zone (pH: 5.0-5.5), the The concentration is relatively low. The carboxyl group (-COOH) in the humic acid-calcium complex will dissociate and release , transforming into . As the pH increases, the degree of dissociation of the carboxyl group increases. After the carboxyl group dissociates, the humic acid-calcium complex carries more negative charges, which enhances its solubility in water. At this time, the complex can diffuse with the movement of water in the soil. Because the pH in the acidified zone is low, a pH gradient is formed. Driven by this gradient, the humic acid-calcium complex in a dissolved state will diffuse from the weakly acidic zone with a higher pH to the acidified zone with a lower pH, thereby achieving targeted migration and continuous improvement of the acidified zone, automatically guiding the complex to be enriched in the acidified zone, and avoiding ineffective dispersion.

[0046] In this technical solution, the preparation steps of the humic acid-calcium complex include:

[0047] Mix the humic acid and calcium gluconate at a molar ratio of 1: (1.5-2.5) and dissolve them in deionized water at a solid-liquid mass ratio of 1: (6-8) to ensure that the humic acid and calcium gluconate react fully and avoid free This can cause local pH fluctuations. Humic acid contains a large number of active functional groups, such as carboxyl and phenolic hydroxyl groups, which can chelate with calcium ions to form a humic acid-calcium complex, reducing electrostatic repulsion with soil colloids. This complex has a stable structure and provides a foundation for subsequent ion transport and migration.

[0048] Deionized water is subjected to ultrasonic chelation, the temperature is controlled at 40-50° C., the power is 250-35 W, the frequency is 30-40 kHz, the pH is controlled at 5.5-6.0, and the ultrasonic chelation is performed for 25-35 minutes to obtain a chelated liquid.

[0049] During the ultrasonic chelation process, the temperature is controlled at 40-50℃, the power is 250-350W, the frequency is 30-40kHz, the pH is 5.5-6.0, and the ultrasonic chelation is 25-35min. This can fully chelate humic acid and calcium gluconate to form a stable humic acid-calcium complex, which can better play the role of neutralizing acidic substances and improving soil structure.

[0050] The chelating liquid and biochar are mixed and shaken in a volume ratio of (3-5):1 and then vacuum dried. Biochar has a large specific surface area and pore structure. The humic acid-calcium complex is achieved through a multi-stage slow release mechanism. The sustained release of calcium can not only quickly neutralize soil acidity, but also avoid calcium waste or local alkalinization caused by short-term excessive release.

[0051] Biochar has certain alkalinity and buffering properties. Working together with the humic acid-calcium complex, it can mitigate drastic fluctuations in soil pH. When soil is exposed to external acidic substances, the biochar and the complex can partially neutralize the acid, maintaining a relatively stable soil pH. The combination of biochar and the humic acid-calcium complex improves the soil microenvironment and promotes the growth and activity of beneficial microorganisms. Microbial metabolic activity can further regulate soil pH and accelerate the decomposition and conversion of acidic substances in the soil, thereby achieving long-term improvement of acidic soils.

[0052] The obtained humic acid-calcium complex was subjected to a sustained release test in a buffer solution with a pH of 4.5. Release half-life hours. The diffusion of HA-Ca is restricted by the biochar mesopores, extending Release half-life, HA-Ca gradually dissociates in the mesopores and interacts with the soil Consumption rate synchronization, maintenance Continuous supply, Slowly and continuously releasing it into the soil will gradually increase the soil pH value and keep it within a relatively stable range, which is beneficial to maintaining the soil acid-base balance and microbial ecological environment.

[0053] In the first acidification zone, apply 2-3 tons / hectare of humic acid-calcium complex, and in the second acidification zone, apply 1.5-2 tons / hectare. The calcium in the humic acid-calcium complex neutralizes active acid in the soil, rebuilding the soil calcium reservoir. The first acidification zone has a high degree of soil acidification, requiring more calcium to neutralize acidic substances, so a larger application rate is required. In the second acidification zone, soil acidity is relatively low, so a smaller application rate can achieve a stable pH.

[0054] Step S300: Apply microbial agent strips to the target soil at a rate of 150-250 kg / ha. The concentration can drop to the safe threshold for spore germination after 6-8 days. Applying humic acid-calcium complex in advance provides a stable environment for subsequent microorganisms. and humic acid carbon sources, avoid high concentrations Directly inhibit spore germination.

[0055] The preparation steps of the microbial agent include: adding malic acid to a humic acid solution with a concentration of 0.08-0.1% and a pH of 6-6.5; mixing spores with the humic acid solution and culturing them to obtain an activated spore liquid; and after culturing, mixing the activated spore liquid with sterilized bentonite in a volume ratio of 1:(3-4) to obtain a spore suspension.

[0056] Low concentration of humic acid (80-100 mg / L) as a slow-release carbon source for microorganisms promotes spore germination and avoids high concentration inhibition. , reducing the damage of metal toxicity to spores.

[0057] Adding malic acid to induce hyphal branching, malic acid can simulate plant root secretions, activate the AM fungus's strigolactone receptor signaling pathway, and increase the hyphal branching frequency by 3 times. In addition, malic acid competes for the chelation of humic acid-calcium complex. , which can accelerate its targeted release, among which AM fungi are arbuscular mycorrhizal fungi (Arbuscular Mycorrhizal Fungi).

[0058] The spores in the activated spore solution are usually in a dormant state. By mixing them with a humic acid solution containing nutrients, the metabolic activity of the spores can be activated, causing them to change from a dormant state to an active growth state. Induce the expression of acid-resistant genes in spores in advance to pre-adapt to the acidified environment.

[0059] After incubation, the activated spore solution is mixed with sterilized bentonite at a volume ratio of 1:3-4 to obtain a spore suspension. Sterilized bentonite can serve as a carrier for microbial spores. Mixing the activated spore solution with bentonite allows the spores to adhere to the surface of the bentonite particles, providing protection. Bentonite protects the spores from external environmental factors, extending their survival.

[0060] The water holding rate of bentonite is >150%, which can provide a stable and slightly moist environment for spore germination. In addition, bentonite gradually releases , which can support the early growth of mycelium.

[0061] In this technical solution, strip application is performed 5 cm below the seed side to ensure efficient connection between the mycelium network and the root system. Compared with broadcast application, strip application improves the utilization rate of the fungus agent.

[0062] It should be noted that the present application enhances calcium transport and organic matter conversion by establishing a mycelial network.

[0063] Humic acid contains easily degradable components that provide a carbon source for fungal spores. It provides the necessary energy and material basis for spore germination, promoting the spore germination rate by more than 50%, allowing the spores to enter the growth stage faster. It can activate microbial calmodulin and increase the frequency of hyphal branching.

[0064] It should be noted that humic acid precipitates in the acidified area to form a chemical gradient field. Since mycelium has a chemotactic response, it will be induced to move towards high The hyphae grow along the surface of the humic acid-calcium complex, increasing the contact area. This directional growth helps the hyphae expand more purposefully in the soil, gradually forming a network structure.

[0065] Mycelial diameter (2-10 μm) is much smaller than soil pores, enabling them to transport humic acid-calcium complexes to micro-domains inaccessible to roots. During this process, mycelium continuously extends and branches in the soil, interacting with the surrounding humic acid-calcium complexes and further promoting the formation and expansion of the mycelial network.

[0066] Humic acid-calcium complex can quickly neutralize active acid in the soil and release it in response to pH , and the soil Exchange reactions occur, reducing soil acidity and improving the soil's acid-base environment.

[0067] After the mycelial network is formed, it can It is transported to the plant roots, providing the plants with necessary calcium nutrition and promoting plant growth and development.

[0068] Apply the microbial inoculant to the target soil using a strip application at a rate of 150-250 kg / hectare. Wait 6-8 days to allow the humic acid-calcium complex to fully react with the soil and improve its chemical properties. The beneficial microorganisms in the inoculant break down organic matter in the soil, releasing nutrients, enhancing soil microbial activity, and promoting the balance and stability of the soil ecosystem. Strip application allows the microbial inoculant to be more concentrated in the soil, enhancing its effectiveness.

[0069] In the first acidified zone (pH < 4.5), a small amount of lime (0.5 t / ha) should be applied one week in advance to raise the pH to 4.8-5.0, and then the above sequence should be followed to avoid direct inoculation which may inactivate the fungus.

[0070] Step S400: Sowing soybean seeds in the target soil at a rate of 25-35 kg / hectare.

[0071] After soybeans grow, spray the leaves with a citric acid solution.

[0072] Activate mineral calcium through root exudates and increase organic input. For example, sow soybean seeds and cover them with 2cm of soil. Spray 0.05% humic acid solution during the sowing to promote germination. Sow seeds after the complex and microbial agent are initially positioned to avoid seed competition. The root system of the green seedlings develops synchronously with the mycelial network, forming a symbiotic system with the complex and bacterial agents in the soil, ultimately achieving the goals of activating mineral calcium, increasing organic input, and improving the soil.

[0073] Sow seeds after 6-8 days to avoid sowing seeds too early to compete with the complex and fungus in the soil. Nutrients such as citric acid and citric acid are needed to ensure a good germination and growth environment for the seeds. After the soybeans have grown, spray the leaves with a citric acid solution. Citric acid has a certain acidity and can be absorbed into the plant through the leaves, affecting the plant's physiological metabolism. On the one hand, citric acid helps regulate the pH value of the plant and enhance the plant's resistance to stress. On the other hand, it promotes the production of plant root secretions. These root secretions can activate mineral calcium in the soil, increase the effectiveness of calcium, and thus provide more calcium nutrition for plant growth.

[0074] Furthermore, the natural water-holding properties of Northeast China's black soil allow the humic acid-calcium complex to reach acidification hotspots within the soil. At the same time, an appropriate moisture content helps maintain the stability of the humic acid-calcium complex, preventing it from settling or agglomerating due to insufficient moisture, which would affect its function.

[0075] The natural water-holding properties of Northeast China's black soil provide a suitable environment for the survival and function of humic acid-calcium complexes and microorganisms. Under suitable moisture conditions, the humic acid-calcium complex can efficiently and effectively target acidification hotspots, precisely locating them and improving the soil. Microorganisms thrive in this moisture environment, forming a dynamic synergistic system with the humic acid-calcium complex. Within this system, microbial activity promotes the decomposition and transformation of the humic acid-calcium complex, releasing more calcium ions and further improving the soil's pH. Simultaneously, the humic acid-calcium complex provides microorganisms with nutrients and a living space, promoting their growth and reproduction. The water-holding properties of Northeast China's black soil are highly compatible with the needs of the humic acid-calcium complex and microorganisms, providing a strong foundation for the efficient remediation of the acidification problem in Northeast China's black soil.

[0076] Furthermore, a 0.05% humic acid solution is sprayed during this period to promote germination. Humic acid contains a variety of nutrients and active substances, such as easily degradable uronic acid. It can provide soybean seeds with a carbon source and other nutrients, promoting seed germination and early growth. Humic acid also improves soil structure and enhances its ability to retain water and fertilizer, further optimizing the soybean growth environment.

[0077] The calcium humate complex and inoculant applied to the soil have formed a mycelial network. During their growth, the roots of the soybean seedlings interact with this network, forming a symbiotic relationship. This symbiosis allows for resource sharing and functional complementarity. The mycelial network helps the soybean roots better absorb nutrients and water from the soil, while soybean root secretions provide the mycelium with carbon sources and other substances, promoting mycelial growth and metabolism, thereby jointly promoting soil improvement and plant growth.

[0078] The present invention achieves efficient repair of the acidification problem of Northeast China black soil by constructing an intelligent improvement system with humic acid as an ion transport promoter. Its core advantage lies in: establishing a targeted migration mechanism, the humic acid-calcium complex accurately locates the acidification hotspot through the dual effects of pH-responsive chemical chemotaxis and soil micro-domain electric field guidance, so that The enrichment efficiency in the pH < 5.0 region is 85%, which is three times higher than that of traditional methods. The AM fungus hyphae network constructs a "biological ion channel" to form a three-dimensional synergy of roots, hyphae and humic acid. Slow release, combined with Northeast black soil, it can increase the pH by 1.5 units and the fluctuation is less than ±0.2.

[0079] This solution combines the characteristics of rapid response and sustained stability. In its application in the black soil area of Jilin Province, it achieved a 37% increase in corn yield and a 91% aluminum toxicity elimination rate, providing an innovative solution for acidified soil management.

[0080] The present invention proposes to construct an improved system using humic acid as an ion transport promoter, which can achieve efficient repair of the acidification problem of Northeast China black soil by establishing a targeted migration mechanism and exerting a dynamic synergistic system. It can not only accurately locate the acidification hotspot area, but also improve The enrichment efficiency can also be improved by forming a three-dimensional synergy of roots, hyphae and humic acid, thus improving the soil ecological environment and achieving The slow release of the pollutants and the stable increase in soil pH value provide new ideas and methods for the acidification control of black soil in Northeast China, and are expected to play an important role in ensuring the sustainable development of agriculture in the black soil region of Northeast China.

[0081] To better understand the technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0082] Soil acidification improvement verification experiment.

[0083] The test site was set up in an experimental field in Jilin. The climatic characteristics of the test site are shown in Table 1, and the physical and chemical properties of the test soil are shown in Table 2.

[0084] ;

[0085] ;

[0086] This experiment used a plot experiment with four experimental cases. The fertilizer application rate for each treatment was consistent with local fertilization practices. The experiment started from April 2022 to October 2023, and the materials were applied in mid-to-late April each spring. Each plot contained six ridges, each ridge was 6 meters long, and the intervals between the plots were 2 meters. The nutrient application rate for each plot was: phosphorus: Potassium: ,nitrogen: Each embodiment / comparative example was repeated 3 times. Example 1

[0087] Treatment method: After spring snowmelt (early May): Apply 2.8 tons / hectare of humic acid-calcium complex after deep plowing 20 cm in the first acidified area.

[0088] Apply thermal insulation with a thickness of 0.01mm to increase the ground temperature by 2-3℃.

[0089] Before the rainy season (June): Inoculate with cold-resistant AM fungi (220 kg / hectare), sow soybeans (25 kg / hectare), and spray with 0.05% citric acid + 0.02% humic acid after sowing and emergence.

[0090] Management during the growing season: Spray 0.05% citric acid on the leaves (3 times with an interval of 15 days). Example 2

[0091] Treatment method: After spring snowmelt (early May): Apply humic acid-calcium complex (1.8 tons / hectare) after deep plowing 20 cm in the second acidification zone.

[0092] Apply thermal insulation with a thickness of 0.01mm to increase the ground temperature by 2-3℃.

[0093] Before the rainy season (June): Inoculate with cold-resistant AM fungi (150 kg / hectare), sow soybeans (25 kg / hectare), and spray with 0.05% citric acid + 0.02% humic acid after sowing and emergence.

[0094] Management during the growing season: Spray 0.05% citric acid on the leaves (3 times with an interval of 15 days). Comparative Example 1

[0095] Treatment method: After the spring snow melt (early May): apply base amendment, apply decomposed cow dung (4 tons / ha, organic matter content 35%), mixed with agricultural lime (2 tons / ha, fineness 80 mesh).

[0096] Apply thermal insulation with a thickness of 0.01mm to increase the ground temperature by 2-3℃.

[0097] Sowing management: Planting corn (variety: Xianyu 335).

[0098] Field management: Conventional irrigation (total irrigation volume 300mm) was applied throughout the entire growth period, and urea was applied (150kg / ha, twice). Comparative Example 2

[0099] Treatment: After spring snowmelt (early May): apply biochar (2.5 t / ha, uncompounded humic acid-Ca).

[0100] Apply thermal insulation with a thickness of 0.01mm to increase the ground temperature by 2-3℃.

[0101] Sowing management: Planting corn (variety: Xianyu 335).

[0102] Field management: Apply urea (150 kg / ha, twice).

[0103] Based on comparative analysis of soil active acid and buffering performance improvement effects.

[0104] ;

[0105] Refer to Table 3, which shows the active acid Neutralization efficiency. Example 1 has the strongest sustained neutralization ability, and the humic acid-calcium complex selectively dissociates in the acidified area (pH < 5.0). Comparative Example 1 is highly efficient at the beginning but rebounds severely due to the depletion of lime. , hydrolysis regeneration .

[0106] ;

[0107] Referring to Table 4, Example 1 has the best buffering capacity in the pH range of 5.0-6.0 (β=48.3), while the buffering capacity of Comparative Example 1 decays rapidly with the dissolution of lime, and the β value decreases by 60% after 12 months.

[0108] ;

[0109] Referring to Table 5, Example 1 significantly reduced the activity, while reducing Regeneration. Redissolution at pH < 5.5 will result in unstable improvement effect.

[0110] ;

[0111] Referring to Table 6, soybean root exudates in Example 1 promoted humic acid formation, with their carboxyl density (4.5 mmol / g) providing the primary buffering site. The cow dung in Comparative Example 1, however, was primarily composed of fulvic acid (H / F = 1.3), resulting in limited buffering capacity.

[0112] Example 1 showed the best performance in active acid neutralization and buffering performance due to its pH-responsive release and the humic acid-calcium complex targeting the acidified area. Humic acid and biochar double buffering. Further AM fungal transport , root secretions activate organic matter to achieve biological synergy.

[0113] The above describes the basic principles, main features, and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any person skilled in the art without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

[0114] In the description of the present invention, each embodiment focuses on the differences from other embodiments, and reference can be made to the same or similar parts between the embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

Claims

1. A method for improving soil acidification in Northeast China, characterized in that: include: Dividing the target soil into the first acidification zone and the second acidification zone according to the parameters of the target soil; Differential application of humic acid-calcium complex in target soils; Apply the microbial inoculant strips to the target soil; Sow soybean seeds into target soil; Measure the parameters of the target soil, and classify the area with pH < 5.0 in the target soil as the first acidification zone, and the area with pH 5.0-5.5 as the second acidification zone; Apply humic acid-calcium complex at 2-3 tons / ha in the first acidification zone of the target soil and 1.5-2 tons / ha in the second acidification zone; Apply microbial inoculant strips to the target soil at a rate of 150-250 kg / ha; Sow soybean seeds at a rate of 25-35 kg / ha into the target soil; The preparation steps of humic acid-calcium complex include: Mix humic acid and calcium gluconate at a molar ratio of 1: (1.5-2.5) and dissolve in deionized water at a solid-liquid mass ratio of 1: (6-8); Perform ultrasonic chelation on deionized water, control the temperature at 40-50°C, the power at 250-35W, the frequency at 30-40kHz, control the pH at 5.5-6.0, and perform ultrasonic chelation for 25-35 minutes to obtain a chelate solution; The chelating liquid and biochar were mixed and shaken in a volume ratio of (3-5):1 and then vacuum dried to obtain a humic acid-calcium complex; The preparation steps of the microbial agent include: Adding malic acid to a humic acid solution having a concentration of 0.08%-0.1% and a pH of 6-6.5; mixing and culturing the spores with the humic acid solution to obtain an activated spore solution; After incubation, the activated spore solution is mixed with sterilized bentonite at a volume ratio of 1:(3-4) to obtain a spore suspension; Add 2%-3% sodium alginate to the spore suspension and drop 2%-3% The solution is solidified, embedded in microcapsules and then dried to obtain the microbial agent.

2. The method for improving soil acidification of Northeast China black soil according to claim 1, characterized in that: After soybeans grow, spray the leaves with a citric acid solution.

3. The method for improving soil acidification of Northeast China black soil according to claim 1, characterized in that: After sowing the soybean seeds, watering is performed and trehalose is added to the water to enhance the metabolic activity of the mycelium.

4. The method for improving soil acidification of Northeast China black soil according to claim 1, characterized in that: Target soil parameters include: pH, exchangeability , organic matter content.

5. The method for improving soil acidification of Northeast China black soil according to claim 1, characterized in that: The size of biochar mesopores is 2-50 nm.

6. The method for improving soil acidification of Northeast China black soil according to claim 1, characterized in that: Before applying microbial agents, measure soil parameters. If the pH of the first acidified zone is less than 4.8, apply lime at a rate of 0.3-0.5 tons / hectare to raise the pH to 4.8-5.

0. Apply microbial agents after 6-8 days.

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