Acidified soil conditioner and preparation method thereof

Abstract

The invention discloses an acidified soil conditioner and a preparation method thereof, the acidified soil conditioner provided by the invention comprises an alkaline material and a complex microbial inoculant, and the alkaline material is selected from at least one of a humic acid material, lobster shell powder and escargot shell powder. The acidified soil conditioner is prepared by mixing the alkaline material and the complex microbial inoculant. Compared with the prior art, the acidified soil conditioner provided by the invention can achieve a relatively good effect of increasing the pH value of acidified soil by adding a relatively small amount of the acidified soil conditioner, can increase the pH value of the acidified soil within a relatively short time, and also has relatively good soil water retention capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and particularly relates to an acidified soil conditioner and a preparation method thereof. Background Art

[0002] Soil acidification refers to the phenomenon that the soil pH decreases and the acidity increases. Both natural processes and human impacts may cause soil acidification. For example, plant roots secrete organic acids, acidic substances are produced during the decomposition of plant residues or litter, and the anions remaining after the application of physiologically acidic fertilizers combine with hydrogen ions in the soil to form strong acids. Soil acidification is one of the main manifestations of soil degradation, which will cause the decrease of soil nutrient availability and soil fertility, the increase of heavy metal activity, and in addition, it will also affect the soil microbial structure and enzyme activity, thereby hindering the growth and development of plants.

[0003] Acidified soil conditioners can be used to repair acidified soil and increase the soil pH. Commonly used acidified soil conditioners include two categories: chemical conditioners and microbial conditioners. Among them: Chemical conditioners (such as mineral lime) improve the acidity of the subsoil slowly, and the excessive use of them will cause the decrease of the bioavailability of micronutrients in the soil; In contrast, microbial conditioners use the metabolic activities of microorganisms to repair acidified soil and have less adverse effects on the environment, so they have received more attention in recent years. At present, due to factors such as the reproduction speed of microorganisms in the soil, microbial conditioners increase the soil pH slowly and are difficult to quickly increase the available phosphorus content in acidified soil.

[0004] CN115404082A discloses an acid soil conditioner and its preparation method and application, which includes the following components: slaked lime, biochar, amphoteric indicator particles, montmorillonite powder and water-retaining particles. However, the amount of acid soil conditioner used is very large, and it is necessary to repeatedly apply the conditioner to the soil for a long time to completely modify the soil.

[0005] CN119432393A discloses a soil conditioner and its preparation method. The soil conditioner provided by this invention is composed of dolomite and urea, and its preparation method is also provided: (1) Weigh dolomite and urea; (2) Grind dolomite and urea respectively and then mix them evenly; (3) Calcinate in a muffle furnace, grind and pass through a pore sieve. This invention combines low-cost raw materials dolomite and urea in a specific ratio, and the preparation method is simple. It can not only improve the acidification of the soil and increase the soil pH, but also increase the permeability of the soil and improve the physical and chemical properties of the soil. However, this soil conditioner has a poor effect on increasing the soil pH and an unsatisfactory effect on improving the soil water retention capacity. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides an acidified soil conditioner and a preparation method thereof. The acidified soil conditioner provided by the present invention can achieve a good effect of increasing the pH of acidified soil with a small amount of addition, can increase the pH of acidified soil in a relatively short time, and also has good soil water retention ability.

[0007] To achieve the above object, the present invention provides an acidified soil conditioner, which is composed of alkaline materials, wherein the alkaline materials are selected from at least one of humic acid materials, lobster shell powder, and snail shell powder.

[0008] Preferably, the humic acid material is humic acid or a humic acid sustained-release hydrogel; the humic acid sustained-release hydrogel is prepared by loading humic acid on a composite hydrogel prepared by mixing modified hyaluronic acid and montmorillonite.

[0009] Preferably, the alkaline materials are mixed by a humic acid material and lobster shell powder or snail shell powder in a weight ratio of 3-7:3-7.

[0010] Preferably, the acidified soil conditioner further comprises a composite microbial agent.

[0011] Preferably, the composite microbial agent is composed of Bacillus megaterium and Bacillus subtilis mixed in a weight ratio of 1:1.2-1.5.

[0012] Preferably, the mass of the composite microbial agent in the acidified soil conditioner is 1-3% of the total weight of the alkaline materials.

[0013] Preferably, the preparation method of the humic acid sustained-release hydrogel comprises the following steps, by weight:

[0014] S1. Add 0.4-0.6 parts of hyaluronic acid to 90-110 parts of water, mix and stir until the hyaluronic acid is dissolved, add 0.9-1 part of triethylamine, mix and stir for 8-12 min, add 0.38-0.41 parts of chloroethyl chloroformate, continue to mix and stir for 1-2 h to obtain a mixed solution A; dissolve 0.18-0.22 parts of cystine in 4-6 parts of PBS solution to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 8-12 min, let stand for 1-3 h, and then dialyze and purify and place it in a ventilated drying oven, and dry at a low temperature of 40-60 °C for 12-24 h to obtain a hyaluronic acid complex;

[0015] S2. Dissolve 0.9 - 1.1 parts of hyaluronic acid complex in 4 - 6 parts of water to form a hyaluronic acid complex solution; add 0.045 - 0.055 parts of montmorillonite to 1 - 3 parts of water, mix and stir for 8 - 12 min, add 0.0016 - 0.0018 parts of sodium polyacrylate, mix and stir for 8 - 12 min to obtain a montmorillonite suspension, then add the above hyaluronic acid complex solution, mix and stir until the mixture loses fluidity to obtain a hydrogel, then after dialysis purification, break the hydrogel into small particles and sieve, and quickly dry for 1 - 2 h through a fluidized bed dryer for standby;

[0016] S3. Immerse 0.4 - 0.6 parts of the hydrogel dried by the fluidized bed in 45 - 55 parts of an aqueous humic acid solution with a concentration of 28 - 32 mg / mL, mix and stir at 28 - 32 °C and 100 - 300 rpm for 25 - 35 min, filter and lay flat on a breathable tray, and dry with hot air circulation at 40 - 50 °C for 6 - 8 h to obtain a humic acid sustained - release hydrogel.

[0017] For further description of the present invention, hyaluronic acid is a linear polysaccharide with a large number of carboxyl and hydroxyl groups on the molecular chain. In the present invention, hyaluronic acid reacts with chloroethyl chloroformate under the catalysis of triethylamine, and the carboxyl group in hyaluronic acid reacts with chloroethyl chloroformate to generate an active ester intermediate; then cystine is added for a mixed reaction, and the active ester intermediate reacts with the amino group in cystine to form an amide bond, grafting cystine onto the hyaluronic acid chain to prepare a hyaluronic acid complex. Montmorillonite is a layered silicate clay mineral with good dispersibility and adsorption properties, and has a large number of negative charges on its surface. Mix the montmorillonite solution with sodium polyacrylate to form a montmorillonite suspension. Montmorillonite is uniformly dispersed in water, and the negative charges on its surface can combine with the negatively charged carboxyl groups of the water - soluble polymer sodium polyacrylate through electrostatic interaction, thereby preventing the aggregation of montmorillonite particles and improving the stability of the suspension. Then, mix and react the prepared hyaluronic acid complex with the montmorillonite suspension. The amino group in the hyaluronic acid complex undergoes electrostatic interaction with the negative charges on the surface of montmorillonite to form a stable three - dimensional network structure, and finally form a hydrogel. Immerse the hydrogel in an aqueous humic acid solution. The hydrogel has a porous three - dimensional network structure, which provides a large number of adsorption sites for humic acid. Humic acid is fixed in the hydrogel by adsorption or by interacting with the components in the hydrogel through functional groups, thereby achieving loading and forming a humic acid sustained - release hydrogel.

[0018] Further preferably, step S1 can also be, by weight parts:

[0019] Add 0.4 - 0.6 parts of hyaluronic acid to 90 - 110 parts of water, mix and stir until the hyaluronic acid dissolves, add 0.9 - 1 part of triethylamine, mix and stir for 8 - 12 min, add 0.38 - 0.41 parts of chloroethyl chloroformate, continue to mix and stir for 1 - 2 h to obtain a mixed solution A; dissolve 0.18 - 0.22 parts of cystine in 4 - 6 parts of PBS solution to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 8 - 12 min, let it stand for 1 - 3 h, then dialyze and purify and place it in a ventilated drying oven, dry at a low temperature of 40 - 60 °C for 12 - 24 h to obtain a mixture; dissolve 1.8 - 2.2 parts of the mixture in 90 - 110 parts of water, then add 0.18 - 0.22 parts of chlorella powder, continuously stir at 100 - 300 rpm for 2 - 5 h, let it stand for 8 - 12 h, then dialyze and purify and freeze-dry to obtain a hyaluronic acid complex.

[0020] For further description of the present invention, the present invention reacts hyaluronic acid with chloroethyl chloroformate under the catalysis of triethylamine, then adds a cystine solution to mix and react to obtain a reaction mixture, and introduces chlorella powder for mixing and reaction. The surface of chlorella cells is rich in various functional groups such as hydroxyl, carboxyl, amino, etc. These functional groups can form hydrogen bonds with the reaction mixture of hyaluronic acid and cystine containing amino and hydroxyl groups, enhancing the interaction between the two, thereby preparing a hyaluronic acid complex. The present invention finds that the introduction of cystine further optimizes the three-dimensional network structure of hyaluronic acid, making the network more compact and stable. This optimized network structure provides more binding sites and space for chlorella powder, enabling the chlorella powder to be better embedded in the network of hyaluronic acid, which is beneficial to enhancing the mechanical stability and water absorption performance of the hydrogel.

[0021] The present invention also provides a preparation method of the above acidified soil conditioner, comprising the following steps:

[0022] Pass the alkaline material through a 100 - 200 mesh sieve, and collect to obtain the acidified soil conditioner;

[0023] Or, pass the alkaline material through a 100 - 200 mesh sieve, then add a composite microbial agent and mix, and collect to obtain the acidified soil conditioner.

[0024] The beneficial effects of the present invention:

[0025] Compared with the prior art, the present invention provides an acidified soil conditioner, which is prepared by mixing a humic acid slow-release hydrogel with lobster shell powder and a composite microbial agent; The acidified soil conditioner provided by the present invention can achieve a good effect of increasing the pH of acidified soil with less dosage, can increase the pH of acidified soil in a relatively short time, and also has good soil water retention ability. Description of the Drawings

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a diagram showing the effects of different alkaline materials on the biomass of corn in high-fertility and low-fertility red soil in Example 1;

[0028] Figure 2 It is a diagram showing the effects of different alkaline materials on the pH of high-fertility and low-fertility red soil in Example 1;

[0029] Figure 3 It is a diagram showing the effects of different alkaline materials on the organic carbon content of high-fertility and low-fertility soil in Example 1;

[0030] Figure 4 It is a diagram showing the effects of different compounded alkaline materials on the soil aggregates of high-fertility and low-fertility soil in Example 1;

[0031] Figure 5 It is a diagram showing the effects of different compounded alkaline materials on the average weight diameter of soil aggregates of high-fertility and low-fertility soil in Example 1. Specific embodiments

[0032] The following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0033] Parameters and sources of specific chemical substances are used.

[0034] Humic acid, commercially available;

[0035] Lobster shell powder, commercially available;

[0036] Snail shell powder, commercially available;

[0037] Montmorillonite, mesh number: 325 mesh;

[0038] Chlorella powder, mesh number: 120 mesh;

[0039] Sodium polyacrylate, CAS number: 9003-04-7;

[0040] Bacillus megaterium, Latin name: Bacillus megaterium, ACCC11011, sourced from Beijing Bio-win Biotechnology Co., Ltd., platform number: bio-52771;

[0041] Bacillus subtilis, Latin name: Bacillus subtilis, ATCC 6051, sourced from Beijing Bio-win Biotechnology Co., Ltd., platform number: bio-72808.

[0042] Example 1

[0043] Pot experiment

[0044] Collect soil samples of two acidification degrees, and pass the soil samples through a 2mm sieve before the experiment to measure the soil pH. The pH of the severely acidified soil is 4.7, and the pH of the moderately acidified soil is 5.3. Divide the above two soils into two groups of experimental groups for pot experiments, namely the high-fertility (moderately acidified soil) group and the low-fertility (severely acidified soil) group. Each group has 11 experimental examples, with 4 pots in each experimental example, and each pot contains 5 kg of soil. Before filling the soil, soil improvement treatment is carried out on each group of pots (mix the soil with alkaline materials and then add fertilizers for mixing). The specific treatment methods of each experimental example are shown in Table 1 below:

[0045] Table 1

[0046]

[0047] Explanation of Table 1 above: Calculate the pot fertilization amount according to the field conversion:

[0048] Weight of 1 hectare of plough layer soil: 1.2 g / cm 3 ×20 cm × 10000 × 10 4 cm 2 =24 × 10 5 kg;

[0049] Fertilizer requirement (g) for 1 kg of soil sample = field application rate / 24 × 10 -5 × 10 3 =0.6 g / kg;

[0050] Considering that the application rate of pot experiments is generally 3 times that of field experiments, 5 kg of soil is 0.6 g / kg × 3 × 5 = 9 g of alkaline materials, that is, the amount of alkaline materials added to the pot is 9 g, equivalent to an addition amount of 0.2%.

[0051] For fertilization, refer to the conventional fertilization rate and application method: The application amounts of N, P2O5, and K2O are 135, 80, and 135 kg / hm 2; and all of them are applied as base fertilizers before sowing maize (i.e., mixing the fertilizers with the soil before planting); the types of nitrogen, phosphorus, and potassium fertilizers applied are urea (containing 46% N), calcium magnesium phosphate fertilizer (containing 12% P2O5), and potassium chloride (containing 60% K2O) respectively. The specific fertilization amount is calculated according to the soil weight as 1.8 g of urea; 4 g of calcium magnesium phosphate fertilizer; 1.4 g of potassium chloride.

[0052] In Table 1 above, the preparation method of the alkaline material for each test example is: passing the alkaline material through a 200-mesh sieve to obtain it.

[0053] Pot experiment: Crops are planted in the 11 test example pots in the above-mentioned high-fertility (generally acidified soil) group and low-fertility (severely acidified soil) group respectively. Maize seeds (maize variety is Zhengdan 958) are sown at the beginning of May, and 2 seeds are sown in each pot. After emergence, only one seedling needs to be retained. During the growth period of maize crops, watering, weeding, and pest control are carried out according to the conventional planting method until the maize is mature.

[0054] At the maize maturity stage, biomass and yield are investigated and test data are recorded. At the same time, the plants are dried and the maize grains and straws are respectively crushed for determining the carbon, nitrogen, phosphorus, and potassium contents of the grains and straws; for soil samples, after the crops are harvested, soil samples are collected, passed through a 2-mm sieve, and the soil pH, exchangeable hydrogen aluminum content, soil organic carbon, available nitrogen, available phosphorus, and available potassium contents are measured and test data are recorded; for better distinction, in the test result data, the data result of test example 1 is correspondingly recorded as blank soil, the data result of test example 2 is correspondingly recorded as fertilized soil, the data result of test example 3 is correspondingly recorded as humic acid; the data result of test example 4 is correspondingly recorded as lobster shell powder, the data result of test example 5 is correspondingly recorded as snail shell powder, the data result of test example 6 is correspondingly recorded as humic acid + lobster shell powder (5-5), the data result of test example 7 is correspondingly recorded as humic acid + snail shell powder (5-5), the data result of test example 8 is correspondingly recorded as humic acid + lobster shell powder (3-7), the data result of test example 9 is correspondingly recorded as humic acid + lobster shell powder (7-3), the data result of test example 10 is correspondingly recorded as humic acid + snail shell powder (7-3), and the data result of test example 11 is correspondingly recorded as humic acid + snail shell powder (3-7).

[0055] The test results of maize yield are shown in Figure 1 ; the test results of soil pH are shown in Figure 2 ; the test results of soil organic carbon content are shown in Figure 3 ; the test results of soil aggregate components are shown in Figure 4 ; the test results of the average weight diameter of soil aggregates are shown in Figure 5 .

[0056] Result analysis:

[0057] According to Figure 1From the pot experiment data, it can be seen that compared with the blank soil and the fertilized soil, applying alkaline materials to the soil, such as applying humic acid, lobster shell powder, snail shell powder alone or in a binary combination, can increase the crop biomass, and the binary combination has a better effect than the single application. Due to different soil fertilities, the optimal mixing ratio between products is also different. For high-fertility soil, Test Example 9 (humic acid and lobster shell powder mixed at a weight ratio of 7:3) has the best effect; for low-fertility soil, the crop biomass in Test Example 8 (humic acid and lobster shell powder mixed at a weight ratio of 3:7) did not increase, while the crop biomass increased under other mixing methods, and Test Example 10 (humic acid and snail shell powder mixed at a weight ratio of 7:3) had the best increasing effect. Therefore, the appropriate proportion of the mixed product can be selected according to the soil fertility.

[0058] According to Figure 2 From the soil pH test data, it can be seen that compared with the blank soil and the fertilized soil, applying alkaline materials to the soil, such as applying humic acid, lobster shell powder, snail shell powder alone or in a binary combination, can significantly increase the soil pH, but the effect of applying the mixed product on increasing the pH is lower than that of applying humic acid alone, especially for high-fertility red soil. In high-fertility red soil, Test Example 3 (humic acid) has the best effect on increasing the soil pH, followed by Test Example 9 (humic acid and lobster shell powder mixed at a weight ratio of 7:3), and then Test Example 10 (humic acid and snail shell powder mixed at a weight ratio of 7:3); in low-fertility red soil, Test Example 9 (humic acid and lobster shell powder mixed at a weight ratio of 7:3) has the best effect on increasing the pH, followed by humic acid, and then Test Example 10 (humic acid and snail shell powder mixed at a weight ratio of 7:3).

[0059] According to Figure 3 From the pot test experiment data, it can be seen that compared with the blank soil, the organic carbon in both high-fertility and low-fertility soils shows a decreasing trend after adding alkaline materials. The reason may be that after adding alkaline materials, the soil is more suitable for crop growth, and the better growth of crops requires a greater amount of organic carbon, resulting in a lack of organic carbon in the soil. Therefore, it is recommended to apply some high-carbon fertilizers in combination in actual production to jointly improve the soil fertility and soil quality.

[0060] From Figure 4It can be seen from the potting test data that the single application of alkaline materials or their binary combinations will reduce the proportion of large soil aggregates and increase the proportion of small soil aggregates, which is more obvious in low-fertility soils. In high-fertility soils, only in Test Example 8 (humic acid and lobster shell powder mixed at a weight ratio of 3:7) with the binary combination of alkaline materials, the proportion of aggregates >2mm is higher than that of the blank soil and the single application of alkaline materials. For other compound treatments, there is a decreasing trend compared with the blank soil and the single application of alkaline materials. Under the action of the binary combination of alkaline materials, the proportions of 0.25-2mm and <0.053mm aggregates show a decreasing trend. In low-fertility soils, the binary combination of alkaline materials significantly reduces the proportion of 0.25-2mm aggregates and increases the proportions of 0.053-0.25mm and <0.053mm aggregates.

[0061] From Figure 5 It can be seen from the potting test data that different compounding methods of alkaline materials have different effects on the mean weight diameter (MWD) of aggregates. For high-fertility soils, in Test Example 9 (humic acid and lobster shell powder mixed at a weight ratio of 7:3) and Test Example 10 (humic acid and snail shell powder mixed at a weight ratio of 7:3) with the binary combination of alkaline materials, the MWD values are the highest, and in Test Example 6 (humic acid and lobster shell powder mixed at a weight ratio of 5:5), the MWD value is the lowest. For low-fertility soils, in Test Example 11 (humic acid and snail shell powder mixed at a weight ratio of 3:7) with the binary combination of alkaline materials, the MWD value is the highest, followed by Test Example 7 (humic acid and snail shell powder mixed at a weight ratio of 5:5) and Test Example 10 (humic acid and snail shell powder mixed at a weight ratio of 7:3). \

[0062] It can be known from the test results of this example that choosing the mixture of humic acid and lobster shell powder at a weight ratio of 7:3 as the alkaline material for soil improvement has the best comprehensive improvement effect compared with other test examples.

[0063] Example 2

[0064] A preparation method of an acidified soil conditioner includes the following steps:

[0065] Pass 40 parts by weight of alkaline materials through a 200-mesh sieve, and collect to obtain the acidified soil conditioner.

[0066] The alkaline material is composed of a humic acid slow-release hydrogel and snail shell powder mixed at a weight ratio of 7:3.

[0067] The preparation method of the humic acid slow-release hydrogel includes the following steps:

[0068] S1. Add 0.5 parts by weight of hyaluronic acid to 100 parts by weight of water, mix and stir until the hyaluronic acid is dissolved, add 0.92 parts by weight of triethylamine, mix and stir for 10 min, add 0.4 parts by weight of chloroethyl chloroformate, continue to mix and stir for 1 h to obtain a mixed solution A; dissolve 0.2 parts by weight of cystine in 5 parts by weight of 1 mol / L PBS solution (pH 7.2) to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 10 min, let it stand for 1 h, then dialyze and purify it, and place it in a ventilated drying oven, and dry it at a low temperature of 45 °C for 24 h to obtain a hyaluronic acid complex;

[0069] S2. Dissolve 1 part by weight of the hyaluronic acid complex in 5 parts by weight of water to form a hyaluronic acid complex solution; add 0.05 parts by weight of montmorillonite to 2 parts by weight of water, mix and stir for 10 min, add 0.0017 parts by weight of sodium polyacrylate, mix and stir for 10 min to obtain a montmorillonite suspension, then add the above-mentioned hyaluronic acid complex solution, mix and stir until the mixture loses fluidity to obtain a hydrogel, then dialyze and purify it, crush the hydrogel into small particles, pass through a 20-mesh sieve, and quickly dry it for 2 h by a fluidized bed dryer (inlet temperature 65 °C, wind speed 4 m / s) for standby;

[0070] S3. Immerse 0.5 part by weight of the fluidized bed-dried hydrogel in 50 parts by weight of an aqueous solution of humic acid with a concentration of 30 mg / mL, mix and stir at 30 °C and 200 rpm for 30 min, filter, spread it on a breathable tray, and dry it by hot air circulation at 50 °C for 7 h to obtain a humic acid slow-release hydrogel.

[0071] Example 3

[0072] A preparation method of an acidified soil conditioner, comprising the following steps:

[0073] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, and collect to obtain the acidified soil conditioner.

[0074] The alkaline material is composed of a humic acid slow-release hydrogel and lobster shell powder mixed in a weight ratio of 7:3.

[0075] The preparation method of the humic acid slow-release hydrogel is the same as that in Example 2.

[0076] Example 4

[0077] A preparation method of an acidified soil conditioner, comprising the following steps:

[0078] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, and collect to obtain the acidified soil conditioner.

[0079] The alkaline material is composed of a humic acid slow-release hydrogel and lobster shell powder mixed in a weight ratio of 7:3.

[0080] The preparation method of the humic acid sustained-release hydrogel comprises the following steps:

[0081] S1. Add 0.5 part by weight of hyaluronic acid to 100 parts by weight of water, mix and stir until the hyaluronic acid is dissolved, add 0.92 part by weight of triethylamine, mix and stir for 10 min, add 0.4 part by weight of chloroethyl chloroformate, continue to mix and stir for 1 h to obtain a mixed solution A; dissolve 0.2 part by weight of cystine in 5 parts by weight of 1 mol / L PBS solution (pH 7.2) to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 10 min, let stand for 1 h, then dialyze and purify, and place it in a ventilated drying oven, dry at a low temperature of 45 °C for 24 h to obtain a mixture; dissolve 2 parts by weight of the mixture in 100 parts by weight of water, then add 0.2 part by weight of chlorella powder, continuously stir at 200 rpm for 3 h, let stand for 10 h, then dialyze and purify and freeze-dry to obtain a hyaluronic acid complex;

[0082] S2. Dissolve 1 part by weight of the hyaluronic acid complex in 5 parts by weight of water to form a hyaluronic acid complex solution; add 0.05 part by weight of montmorillonite to 2 parts by weight of water, mix and stir for 10 min, add 0.0017 part by weight of sodium polyacrylate, mix and stir for 10 min to obtain a montmorillonite suspension, then add the above hyaluronic acid complex solution, mix and stir until the mixture loses fluidity to obtain a hydrogel, then dialyze and purify, break the hydrogel into small particles, pass through a 20-mesh sieve, and quickly dry for 2 h by a fluidized bed dryer (inlet temperature 65 °C, wind speed 4 m / s) for standby;

[0083] S3. Immerse 0.5 part by weight of the hydrogel dried by the fluidized bed in 50 parts by weight of an aqueous humic acid solution with a concentration of 30 mg / mL, mix and stir at 30 °C and 200 rpm for 30 min, filter, spread it on a breathable tray, and dry by hot air circulation at 50 °C for 7 h to obtain the humic acid sustained-release hydrogel.

[0084] Example 5

[0085] A preparation method of an acidified soil conditioner comprises the following steps:

[0086] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, then add 0.6 part by weight of the compound microbial agent and mix to collect the acidified soil conditioner.

[0087] The alkaline material is composed of a humic acid sustained-release hydrogel and lobster shell powder mixed in a weight ratio of 7:3.

[0088] The compound microbial agent is composed of Bacillus megaterium and Bacillus subtilis mixed in a weight ratio of 1:1.3.

[0089] The preparation method of the humic acid sustained-release hydrogel is the same as that in Example 4.

[0090] Comparative Example 1

[0091] A preparation method of an acidified soil conditioner, comprising the following steps:

[0092] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, then add 0.6 part by weight of the compound bacterial agent and mix, and collect to obtain the acidified soil conditioner.

[0093] The alkaline material is composed of humic acid slow-release hydrogel and lobster shell powder mixed in a weight ratio of 7:3.

[0094] The compound bacterial agent is composed of Bacillus megaterium and Bacillus subtilis mixed in a weight ratio of 1:1.3.

[0095] The preparation method of the humic acid slow-release hydrogel comprises the following steps:

[0096] S1. Add 2 parts by weight of hyaluronic acid to 100 parts by weight of water, mix and stir until the hyaluronic acid is dissolved, then add 0.2 part by weight of chlorella powder, continuously stir at 200 rpm for 3 h, let stand for 10 h, then dialyze and purify and freeze-dry to obtain a hyaluronic acid complex;

[0097] S2. Dissolve 1 part by weight of the hyaluronic acid complex in 5 parts by weight of water to form a hyaluronic acid complex solution; add 0.05 part by weight of montmorillonite to 2 parts by weight of water, mix and stir for 10 min, add 0.0017 part by weight of sodium polyacrylate, mix and stir for 10 min to obtain a montmorillonite suspension, then add the above hyaluronic acid complex solution, mix and stir until the mixture loses fluidity to obtain a hydrogel, then dialyze and purify and crush the hydrogel into small particles, pass through a 20-mesh sieve, and quickly dry for 2 h by a fluidized bed dryer (inlet temperature 65 °C, wind speed 4 m / s) for standby;

[0098] S3. Immerse 0.5 part by weight of the fluidized bed-dried hydrogel in 50 parts by weight of a humic acid aqueous solution with a concentration of 30 mg / mL, mix and stir at 30 °C and 200 rpm for 30 min, filter and spread it on a breathable tray, and dry by hot air circulation at 50 °C for 7 h to obtain the humic acid slow-release hydrogel.

[0099] Comparative Example 2

[0100] A preparation method of an acidified soil conditioner, comprising the following steps:

[0101] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, then add 0.6 part by weight of the compound bacterial agent and mix, and collect to obtain the acidified soil conditioner.

[0102] The alkaline material is composed of humic acid and lobster shell powder mixed in a weight ratio of 7:3.

[0103] The composite bacterial agent is composed of Bacillus megaterium and Bacillus subtilis, which are mixed according to a weight ratio of 1:1.3.

[0104] Comparative Example 3

[0105] A preparation method of an acidified soil conditioner includes the following steps:

[0106] Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, then add 0.6 parts by weight of the composite bacterial agent and mix, and collect to obtain the acidified soil conditioner.

[0107] The alkaline material is composed of humic acid and snail shell powder, which are mixed according to a weight ratio of 7:3.

[0108] The composite bacterial agent is composed of Bacillus megaterium and Bacillus subtilis, which are mixed according to a weight ratio of 1:1.3.

[0109] Test Example 1

[0110] Humic acid is a kind of high-molecular organic compound formed during the microbial decomposition and chemical synthesis processes of animal and plant residues. It is widely present in soil, peat, lignite and weathered coal, and is a natural organic substance. Humic acid is rich in elements such as carbon, hydrogen, oxygen and nitrogen, and can significantly improve the physical and chemical properties of soil, increase soil fertility and water retention. In addition, humic acid can also undergo a complexation reaction with soil minerals to form stable complexes, enhance soil stability, and play an important role in promoting the healthy growth of plants.

[0111] The humic acid loading rate test can determine the content of humic acid in the slow-release hydrogel. A higher loading rate means more humic acid is fixed in the hydrogel, thus playing a more lasting improvement role in the soil; the slow-release rate test is used to evaluate the release speed and cycle of humic acid from the hydrogel. A hydrogel with good slow-release performance can slowly release humic acid over a long period of time, which helps the humic acid to be evenly and stably distributed in the soil, fully play its improvement role, thereby continuously regulating the soil environment and reducing the impact on the environment.

[0112] In the preparation process of the acidified soil conditioners in Examples 2-5 and Comparative Example 1 of the present invention, a humic acid slow-release hydrogel is added. Considering that the preparation methods of the humic acid slow-release hydrogels in Example 2 and Example 3 are the same, and the preparation methods of the humic acid slow-release hydrogels in Example 4 and Example 5 are the same, therefore, in this test example, the humic acid slow-release hydrogels prepared in Example 3 and Example 5 are selected for the humic acid loading rate and slow-release rate tests.

[0113] Humic acid loading rate test

[0114] The total mass of humic acid added during the preparation of the humic acid slow-release hydrogel is W 总, the hydrogel prepared after freeze-drying. This test example tests the humic acid loading of the humic acid slow-release hydrogel. By placing the hydrogels prepared in Example 3, Example 5 and Comparative Example 1 in 60 mL of ammonia-ammonium chloride buffer with a pH of 10, and then using a cell crusher to break for 1 h, the content of humic acid free in the solution is W HA , and the humic acid loading rate of the hydrogel beads is calculated by the following formula:

[0115] Loading rate = (W HA / W 总 ) × 100%

[0116] The test results are averaged, and the specific test data are shown in Table 2.

[0117] Test of humic acid slow-release rate

[0118] Put 0.1 g of the hydrogels prepared in Example 3, Example 5 and Comparative Example 1 into 100 mL of acetic acid-sodium acetate buffer (pH = 6), and then place them at room temperature for 30 h, 80 h, 160 h, 240 h respectively. Then, extract 10 mL of the supernatant, and add 10 mL of buffer solution with the same pH to the corresponding system. Then, centrifuge the extracted supernatant, take the centrifuged solution, detect the humic acid concentration with a UV spectrophotometer at 271 nm, conduct 5 parallel detections, collect the detection data, and calculate the cumulative release amount of humic acid by the following formula:

[0119]

[0120] In the formula: C t is the mass concentration of the solution at time t, mg / mL; V t is the volume of the solution at time t, mL; V 总 is the total volume of the solution, mL; m0 is the total weight of humic acid in the hydrogel, mg.

[0121] The test results are averaged, and the specific test data are shown in Table 2.

[0122] Table 2 Humic acid loading and release conditions

[0123]

[0124] By analyzing the data in Table 2 and comparing Example 3, Example 5 and Comparative Example 1, it can be seen that the humic acid loading rates of Example 3 and Example 5 are significantly better than that of Comparative Example 1, indicating that the humic acid sustained-release hydrogel prepared in the examples of the present invention has a good humic acid loading effect. The reason may be that the prepared humic acid sustained-release hydrogel is composed of components such as hyaluronic acid complex and montmorillonite. The hyaluronic acid complex contains a large number of functional groups such as carboxyl, hydroxyl and amino groups. These functional groups can form stable chemical bonds with the carboxyl, phenolic hydroxyl and other functional groups in humic acid through electrostatic interaction, hydrogen bond, etc., so as to firmly adsorb humic acid in the network structure of the hydrogel; and after adding montmorillonite during the preparation of the hydrogel, the negative charge of montmorillonite can have an electrostatic interaction with the positive charge in humic acid, thereby further enhancing the adsorption capacity of the hydrogel for humic acid.

[0125] By comparing Example 3 and Example 5, it is found that the loading rate of Example 5 is higher than that of Example 3. The reason may be that compared with Example 3, Chlorella powder is introduced during the preparation of the hydrogel in Example 5. The functional groups in Chlorella powder form hydrogen bonds and electrostatic interactions with the amino and hydroxyl groups in the hyaluronic acid complex, enhancing the stability of the hyaluronic acid complex. This enhanced stability makes the hydrogel network more compact and can better adsorb and fix humic acid; and the introduction of Chlorella powder further enhances the three-dimensional network structure of the hydrogel, increases the specific surface area and adsorption sites of the hydrogel, so that more humic acid can be adsorbed into the network of the hydrogel, and thus has better loading capacity.

[0126] By comparing Example 3, Example 5 and Comparative Example 1, it can be seen that the humic acid release amount of Comparative Example 1 within 30 h is significantly higher than that of Example 3 and Example 5, and the humic acid release amount within 240 h is also significantly higher than that of Example 3 and Example 5, and the sustained-release effect is poor, while the sustained-release effects of Example 3 and Example 5 are better; by comparing the humic acid sustained-release rates of Example 3 and Example 5 within 240 h, the sustained-release effect of Example 5 is better than that of Example 3. The reason may be that humic acid is adsorbed in the three-dimensional network of the hydrogel and fixed through physical adsorption and chemical bonding. In the soil environment, the hydrogel network gradually degrades and humic acid is gradually released to provide continuous fertility. Chlorella powder is introduced during the preparation of the humic acid sustained-release hydrogel. The functional groups in Chlorella powder not only enhance the adsorption capacity, but also make the release of humic acid in the hydrogel network slower and more uniform through the formation of dynamic hydrogen bonds and electrostatic interactions. This dynamic interaction makes the release of humic acid in the soil more persistent and avoids the waste of fertility caused by rapid release. In addition, the introduction of Chlorella powder enhances the mechanical stability of the hydrogel, enabling the hydrogel to better maintain its structure in the soil environment and reducing the rapid release of humic acid caused by mechanical damage, thereby further optimizing the sustained-release effect of humic acid.

[0127] Test Example 2

[0128] Soil Water Retention Capacity Test

[0129] Soil water retention capacity refers to the ability of soil to retain and store water for plant uptake and utilization after rainfall or irrigation. The water retention capacity of soil can promote the growth and development of plant roots by regulating soil temperature and help plants maintain growth under drought conditions. The strength of soil water retention capacity is crucial for crop growth and agricultural production, and can have an intuitive impact on crop yield, drought resistance, root growth, and growth cycle. The soil water loss rate can reflect the strength of soil water retention capacity because it directly reflects the amount of water lost by the soil within a specific time, which is an important indicator for measuring soil water retention capacity.

[0130] Determination of soil water loss rate: Place fresh soil in an oven at 60 °C and dry it for 48 h to obtain dry soil; then, put 100 g of dry soil into plastic containers respectively, and then add 0.2 g of the soil conditioners prepared in Examples 1-5 and Comparative Examples 1-3 and mix them completely to obtain the mixed soils of Examples 1-5 and Comparative Examples 1-3. The preparation method of the acidified soil conditioner selected in Example 1 is: pass 40 parts by weight of alkaline material through a 200-mesh sieve, and collect the acidified soil conditioner. The alkaline material is composed of humic acid and lobster shell powder mixed in a weight ratio of 7:3; in addition, to form a control effect, take 100 g of dry soil as the control group; spread the obtained mixed soils of each group and the control group soil in containers, and then water the mixed soils with 100 mL of distilled water and weigh (W0); each group of containers is stored under natural light conditions and weighed for up to 30 days (W n ). We measured the soil water loss rate (SWL) in the soil on the 5th, 10th, 15th, and 30th days within 30 days, and calculated the soil water loss rate (%) using the following formula:

[0131] SWL(%) = (W0 - W n ) / W0 × 100%

[0132] The test results are averaged, and the specific test data are shown in Table 3.

[0133] Table 3 Soil Water Retention Capacity Test of Each Group

[0134]

[0135]

[0136] As can be seen from Table 3, compared with the control group, the soil water loss rates of Examples 1-5 and Comparative Examples 1-3 are significantly lower than those of the control group, indicating that the acidified soil conditioner prepared by the present invention has a good effect of improving the water retention capacity of the soil. By comparing Examples 1-5 and Comparative Examples 1-3, it is found that the soil water loss rates of Examples 2-5 and Comparative Example 1 are significantly lower than those of Example 1 and Comparative Examples 2-3, indicating that compared with the soil conditioner added with humic acid, the soil conditioner added with humic acid slow-release hydrogel has a better effect of improving the water retention capacity of the soil. The reason may be that firstly, humic acid itself has strong water absorption and water retention capacities, and its porous structure can adsorb several times its own weight of water, thus improving the water retention capacity of the soil; secondly, the humic acid slow-release hydrogel prepared by the present invention is composed of components such as hyaluronic acid complex and montmorillonite, forming a three-dimensional cross-linked hydrophilic polymer network. The cross-linking points between polymer chains connect different polymer chains together to form tiny pores, which can accommodate a large amount of water molecules. Therefore, this network structure has high hydrophilicity and porosity, can absorb a large amount of water and maintain a stable gel state, so that a large amount of water can be stored in the soil, reducing water evaporation and loss. When humic acid combines with the hydrogel, the two act synergistically, significantly enhancing the overall water retention capacity.

[0137] By comparing Examples 2-5 and Comparative Example 1, it is found that the soil water loss rates of Examples 4-5 and Comparative Example 1 are significantly lower than those of Examples 2-3, and the soil water loss rate of Example 5 is the lowest, having a good effect of improving the water retention capacity of the soil. The reason may be that compared with Examples 2-3, Chlorella powder is introduced in the preparation process of the humic acid slow-release hydrogel in Examples 4-5 and Comparative Example 1. The functional groups in Chlorella powder form hydrogen bonds and electrostatic interactions with the hyaluronic acid complex, increasing the specific surface area and adsorption sites of the hydrogel and improving the adsorption capacity of the hydrogel; and the introduction of Chlorella powder further optimizes the three-dimensional network structure of the hydrogel, making the network more compact and stable, and capable of better retaining water; in addition, the functional groups in Chlorella powder can form dynamic hydrogen bonds with water molecules in the soil environment, enabling the hydrogel to continuously adsorb and retain water, reducing water evaporation and loss, thereby further enhancing the soil water retention capacity.

[0138] Comparing Example 5 with Comparative Example 1, it was found that in the preparation of the humic acid sustained-release hydrogel, introducing hyaluronic acid and chlorella powder to prepare a hyaluronic acid complex in Comparative Example 1, while in Example 5 of the present invention, introducing hyaluronic acid, cystine and chlorella powder to prepare a hyaluronic acid complex during the preparation of the humic acid sustained-release hydrogel was more conducive to further improving the soil water retention capacity. The reason for the analysis might be that the introduction of cystine and chlorella powder further optimized the three-dimensional network structure of hyaluronic acid, making the network more compact and stable. This optimized network structure can not only better retain water but also reduce water loss and improve the water absorption performance of the hydrogel.

[0139] Test Example 3

[0140] Test for the effect of improving soil pH

[0141] Carry out a pot experiment according to the method provided in Reference Example 1, and respectively test the effect of the acidified soil improvers prepared in Examples 1-5 and Comparative Examples 1-3 on improving soil pH.

[0142] To improve the experimental efficiency, simplify the pot experiment and conduct the test in the following way:

[0143] Respectively take 9 g of the acidified soil improvers prepared in Examples 1-5 and Comparative Examples 1-3 for standby. The preparation method of the acidified soil improver selected in Example 1 is as follows: Pass 40 parts by weight of the alkaline material through a 200-mesh sieve, and collect the acidified soil improver. The alkaline material is composed of humic acid and lobster shell powder mixed in a weight ratio of 7:3. Collect severely acidified soil as the soil sample, and pass the soil sample through a 2-mm sieve before the experiment implementation, and measure the soil pH to be 4.7; conduct a pot experiment on the above soil, set 8 experimental examples, with 4 pots in each group, and each pot contains 5 kg of soil; before filling the soil in each group of pots, conduct soil improvement. The specific improvement method is: Mix 5 kg of soil with 9 g of the acidified soil improver, and then add 1.8 g of urea, 4 g of calcium magnesium phosphate fertilizer, and 1.4 g of potassium chloride for mixing.

[0144] Pot experiment: Plant crops in the above 8 example pots respectively. Sow corn seeds (the corn variety is Zhengdan 958) at the beginning of May. Sow 2 seeds in each pot, and keep only one seedling after emergence. During the growth of the corn crop until it matures, collect soil samples through a 2-mm sieve at the same time every day to measure the soil pH until the collection stops when the detected soil is raised from the initial pH = 4.7 to pH = 6.5. Record the time required for the soil pH in different experimental examples to be raised to 6.5. Put the collected soil back into the corresponding pots; and after the corn crop is harvested, collect soil samples, pass them through a 2-mm sieve, measure the soil pH after the corn crop is harvested and record the test data; the specific test data are shown in Table 4 below.

[0145] Table 4

[0146]

[0147] As can be seen from Table 4, from the test results of the soil pH value after harvesting corn crops, compared with the initially severely acidified soil, the soil pH value has been significantly increased after using the acidified soil conditioner, indicating that it has a good improvement effect. By comparing Examples 1-5 and Comparative Examples 1-3, it can be seen that the time required for the pH of Example 5 and Comparative Examples 1-3 to increase to 6.5 is less than that of Examples 1-4, indicating that the acidified soil conditioner added with the compound microbial agent has a better improvement effect; the reason may be that during the growth and reproduction of Bacillus megaterium and Bacillus subtilis in the compound microbial agent in the soil, Bacillus megaterium helps to dissolve the fixed phosphorus in the soil and increase the available phosphorus content, while Bacillus subtilis will metabolize and produce some alkaline substances, such as ammonia, etc. These alkaline substances can neutralize the acidic components in the soil, thereby increasing the soil pH value, and the compound microbial agent can accelerate the decomposition of organic matter (such as lobster shell powder) in the soil, convert it into nutrients more easily absorbed by plants, and release alkaline substances at the same time, further increasing the soil pH value.

[0148] By comparing Example 5 and Comparative Examples 1-3, it is found that the time required for the pH of Example 5 and Comparative Example 1 to increase to 6.5 is less than that of Comparative Examples 2-3, indicating that compared with the soil conditioner added with humic acid, the soil conditioner added with humic acid slow-release hydrogel has a better soil pH increase effect. The reason may be that the humic acid slow-release hydrogel has better water retention than humic acid and also has a slow-release property. The water retention and slow-release properties of the humic acid slow-release hydrogel provide more suitable survival conditions for the microorganisms in the compound microbial agent, promote the growth and metabolism of the microorganisms, increase the reproduction rate of the microorganisms in the soil, enable the microorganisms to decompose organic substances more effectively, release alkaline substances, and thus quickly increase the soil pH value; at the same time, the metabolites of the microorganisms further enhance the buffering capacity of the humic acid slow-release hydrogel, and the two work together to significantly increase the soil pH value. In addition, lobster shell powder itself contains rich calcium and other minerals, and these components can directly neutralize the acidic substances in the soil and increase the soil pH value. In the system of the humic acid slow-release hydrogel, the role of lobster shell powder can be better exerted because the water retention and slow-release properties of the hydrogel help to maintain the moist state of the soil and promote the dissolution and neutralization of lobster shell powder.

[0149] Comparing Example 5 with Comparative Example 1, it is found that the effect of improving soil pH in Example 5 is better than that in Comparative Example 1. This shows that compared with Comparative Example 1, in the preparation process of the humic acid slow-release hydrogel, introducing hyaluronic acid and chlorella powder to prepare the hyaluronic acid complex, in Example 5 of the present invention, introducing hyaluronic acid, cystine and chlorella powder to prepare the hyaluronic acid complex is more conducive to further improving the soil water retention capacity. The reason may be that the introduction of cystine and chlorella powder further optimizes the three-dimensional network structure of hyaluronic acid, making the network more compact and stable, thereby enhancing the structural stability of the hyaluronic acid complex. This stable structure enables the hydrogel to better load and slowly release effective components such as humic acid, so as to more effectively regulate the soil acid-base balance and increase the soil pH value. And the combination of hyaluronic acid, cystine and chlorella powder can provide richer nutrients and a more suitable living environment for the microorganisms in the composite microbial agent used for soil improvement together. The microorganisms can more effectively decompose organic substances and release alkaline substances in a suitable environment, thereby further increasing the soil pH value.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An acidified soil conditioner, characterized in that, The acidified soil conditioner is composed of alkaline materials, wherein the alkaline materials are selected from at least one of humic acid materials, lobster shell powder, and snail shell powder; the humic acid material is humic acid or a humic acid slow-release hydrogel; the humic acid slow-release hydrogel is prepared by loading humic acid on a composite hydrogel prepared by mixing modified hyaluronic acid and montmorillonite.

2. The acidified soil conditioner according to claim 1, characterized in that: The alkaline materials are mixed by a humic acid material and lobster shell powder or snail shell powder at a weight ratio of 3-7:3-7.

3. The acidified soil conditioner according to claim 1 or 2, characterized in that: The acidified soil conditioner further includes a compound microbial agent.

4. The acidified soil conditioner according to claim 3, characterized in that: The compound microbial agent is composed of Bacillus megaterium and Bacillus subtilis mixed at a weight ratio of 1:1.2-1.

5.

5. The acidified soil conditioner according to claim 3, wherein: The mass of the compound microbial agent in the acidified soil conditioner is 1-3% of the total weight of the alkaline materials.

6. The acidified soil conditioner according to claim 1, wherein: The preparation method of the humic acid slow-release hydrogel includes the following steps, by weight: S1. Add 0.4-0.6 parts of hyaluronic acid to 90-110 parts of water, mix and stir until the hyaluronic acid is dissolved, add 0.9-1 part of triethylamine, mix and stir for 8-12 min, add 0.38-0.41 parts of chloroethyl chloroformate, continue to mix and stir for 1-2 h to obtain a mixed solution A; dissolve 0.18-0.22 parts of cystine in 4-6 parts of PBS solution to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 8-12 min, let it stand for 1-3 h, then dialyze and purify it, and place it in a ventilated drying oven, and dry it at a low temperature of 40-60 °C for 12-24 h to obtain a hyaluronic acid complex; S2. Dissolve 0.9-1.1 parts of the hyaluronic acid complex in 4-6 parts of water to form a hyaluronic acid complex solution; Add 0.045-0.055 parts of montmorillonite to 1-3 parts of water, mix and stir for 8-12 min, add 0.0016-0.0018 parts of sodium polyacrylate, mix and stir for 8-12 min to obtain a montmorillonite suspension, then add the above hyaluronic acid complex solution, mix and stir until the mixture loses fluidity to obtain a hydrogel, then dialyze and purify it, crush the hydrogel into small particles and screen them, and quickly dry them for 1-2 h by a fluidized bed dryer for standby; S3. Immerse 0.4-0.6 parts of the hydrogel dried by the fluidized bed in 45-55 parts of a humic acid aqueous solution with a concentration of 28-32 mg / mL, mix and stir at 28-32 °C and 100-300 rpm for 25-35 min, filter and spread it on a breathable tray, and dry it by hot air circulation at 40-50 °C for 6-8 h to obtain a humic acid slow-release hydrogel.

7. The acidified soil conditioner according to claim 6, characterized in that: Step S1 can also be, by weight: Add 0.4 - 0.6 parts of hyaluronic acid to 90 - 110 parts of water, mix and stir until the hyaluronic acid is dissolved, add 0.9 - 1 part of triethylamine, mix and stir for 8 - 12 min, add 0.38 - 0.41 parts of chloroethyl chloroformate, continue to mix and stir for 1 - 2 h to obtain a mixed solution A; dissolve 0.18 - 0.22 parts of cystine in 4 - 6 parts of PBS solution to obtain a cystine solution, then add it to the mixed solution A, mix and stir for 8 - 12 min, let it stand for 1 - 3 h, then dialyze and purify it, and place it in a ventilated drying oven, dry at a low temperature of 40 - 60 °C for 12 - 24 h to obtain a mixture; dissolve 1.8 - 2.2 parts of the mixture in 90 - 110 parts of water, then add 0.18 - 0.22 parts of chlorella powder, continuously stir at 100 - 300 rpm for 2 - 5 h, let it stand for 8 - 12 h, then dialyze and purify it and freeze-dry to obtain a hyaluronic acid complex.

8. A method for preparing the acidified soil conditioner according to any one of claims 1-7, characterized in that, Comprising the following steps: Pass the alkaline material through a 100 - 200 mesh sieve, and collect to obtain an acidified soil conditioner; Or, pass the alkaline material through a 100 - 200 mesh sieve, then add a compound microbial agent and mix, and collect to obtain an acidified soil conditioner.

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