A soil conditioner for soil acidification control and its preparation method and application

Abstract

This application relates to the technical field of soil conditioners, and more particularly to a soil conditioner for soil acidification treatment, its preparation method, and its application. The soil conditioner comprises the following components, by weight: 20-35 parts red mud, 10-15 parts humic acid-sodium alginate complex, 10-15 parts zeolite, 5-8 parts silicon-calcium-magnesium fertilizer, 4-8 parts acid-resistant bacteria agent, and 10-15 parts bio-based adhesive. This application can achieve better and longer-lasting effects on acidified soil treatment.

Description

Technical Field

[0001] The present application relates to the technical field of soil conditioners, and in particular to a soil conditioner for soil acidification control, and a preparation method and application thereof. Background Art

[0002] Soil acidification refers to the process in which soil pH decreases and soil acidity increases due to an increase in hydrogen ion (H⁺) concentration or the loss of basic ions (such as Ca²⁺, Mg²⁺, and K⁺). Soil acidification poses multiple risks to agricultural ecosystems, crop growth, and environmental health, specifically:

[0003] 1. Soil structure damage

[0004] The compaction and acidification of the soil lead to the collapse of the soil aggregate structure, forming dense blocks, reducing the porosity by 30%-50%, increasing the resistance to root extension, and easily forming "old and dead seedlings"; the loss of water and fertilizer retention capacity and the acidic environment accelerate the leaching of basic ions such as calcium, magnesium, and potassium, reducing the soil water holding capacity by 20%-40%, and intensifying the loss of nutrients with water.

[0005] Second, nutrient imbalance and decreased effectiveness lead to the ineffectiveness of numerous elements. The effectiveness of nitrogen, phosphorus, and potassium decreases with decreasing pH. When pH is <5.0, phosphorus fixation increases by 40%-60%, leading to frequent crop nutrient deficiencies. Toxic elements are activated, increasing the concentrations of free ions such as aluminum, manganese, and iron, leading to root poisoning (for example, aluminum poisoning wheat roots can reduce yields by 30%-50%). Beneficial bacteria are suppressed, with the number of beneficial microorganisms such as ammonifying and nitrogen-fixing bacteria decreasing by 60%-80%, hindering nitrification and causing a 40% decrease in nitrogen fertilizer utilization efficiency.

[0006] Therefore, it is necessary to treat acidified soil to reduce the above-mentioned hazards. At present, soil conditioners are mainly used in the treatment of acidified soil. Soil conditioners for soil acidification treatment restore soil health by neutralizing acidity, replenishing base ions, and improving soil structure. Traditional acidic soil conditioners mostly directly use quicklime, slaked lime and limestone powder, which have a significant effect in raising pH, but long-term application leads to the potential risk of "sub-ashing" or re-acidification of the soil; in addition, oyster shells are also widely used due to their advantages such as easy acquisition, low price and environmental friendliness, but they have potential heavy metal risks. Therefore, there is still a lot of room for improvement in soil conditioners. Summary of the Invention

[0007] In a first aspect, the present application provides a soil conditioner for soil acidification control.

[0008] This application adopts the following technical solutions:

[0009] A soil conditioner for soil acidification control comprises the following components by weight: 20-35 parts of red mud, 10-15 parts of humic acid-sodium alginate complex, 10-15 parts of zeolite, 5-8 parts of silicon calcium magnesium fertilizer, 4-8 parts of acid-resistant bacteria agent, and 10-15 parts of bio-based adhesive.

[0010] By adopting the above technical solution, firstly, red mud is rich in Fe2O3 and CaO, which can fix heavy metals (such as Cd²⁺ and Pb²⁺) through ion exchange and precipitation, and can cooperate with zeolite to adjust the pH, thereby conditioning the acidic soil; humic acid contains a large number of carboxyl groups. In acidic soil, the protonated molecules of the carboxyl group are negatively charged, and the soil acidity is neutralized by electrostatic adsorption of H⁺. In addition, humic acid chelates heavy metals, and sodium alginate combines with heavy metals through carboxylic acid groups to form a stable chelate. The two are cross-linked to form a gel network, which enhances water and fertilizer retention, thereby promoting plant growth; acid-resistant bacteria can remain active in an acidic environment, secrete a variety of secondary metabolites, promote crop root development, and cooperate with silicon, calcium and magnesium fertilizers to condition the soil and improve the soil's acid resistance.

[0011] Optionally, the humic acid-sodium alginate complex is prepared by the following method: dissolving humic acid and sodium alginate separately, mixing the solutions thereof, adding polyethylene glycol, continuously stirring the mixture for reaction, and then drying and crushing the mixture to obtain the humic acid-sodium alginate complex.

[0012] By adopting the above technical solution, the humic acid-sodium alginate complex is cross-linked to form a network structure, which can effectively control the loss rate of humic acid, thereby improving the durability of the conditioner in conditioning acidified soil. In addition, under the action of polyethylene glycol, the cross-linking effect can be further enhanced, further improving the stability of the overall system.

[0013] Optionally, 1-3 parts of polyglutamic acid are further included by weight.

[0014] By adopting the above technical solution, polyglutamic acid acts as a water-retaining agent and heavy metal chelating agent, forming a three-dimensional network with the humic acid-sodium alginate complex, thereby improving the overall structural stability. In addition, the adsorption capacity of polyglutamic acid for Ca²⁺ and Mg²⁺ is 100 times that of natural soil. It can replace H⁺ and Al³⁺ on soil colloids, increase base saturation, and reduce soil exchangeable acidity.

[0015] Optionally, the bio-based adhesive is selected from corn starch.

[0016] By adopting the above technical solution, the corn starch molecular chain forms a coating effect with the particles through hydrogen bonds and van der Waals forces, thereby improving the durability of acid conditioning. The hydroxyl groups on the starch molecular chain form five-membered ring chelates with Ca²⁺ and Mg²⁺, which enhances the retention time of base ions in the soil and reduces the competitive adsorption of Al³⁺ and H⁺. In addition, the degradation products of corn starch can provide energy for acid-resistant bacteria agents, promoting the added value and effect of acid-resistant bacteria agents.

[0017] Optionally, the zeolite is surface-modified by an epoxy silane coupling agent.

[0018] Optionally, the zeolite is modified by the following steps: dissolving 3-glycidyloxypropyltriethoxysilane in an ethanol solution, adding zeolite particles to the ethanol solution of 3-glycidyloxypropyltriethoxysilane, stirring to react, and then filtering and drying to obtain a surface-modified zeolite.

[0019] By adopting the above technical solution, the zeolite is surface-modified by an epoxy silane coupling agent, so that the zeolite surface has epoxy groups. The epoxy groups are easily ring-opening polymerized with the hydroxyl groups in the corn starch chain segments, so that the corn starch can be better coated on the zeolite surface, thereby improving the mechanical strength of the overall structure and having better durability.

[0020] Optionally, the acid-resistant bacterial agent is selected from one or more of phosphate-solubilizing bacteria, Bacillus subtilis, Brevibacillus laterosporus and Brevibacillus laterosporus.

[0021] By adopting the above technical solution, the above acid-resistant bacterial agent has the characteristics of rapid colonization and reproduction, can inhibit the reproduction of other pathogenic microorganisms, has strong acid and alkali resistance, and can maintain activity in an acidic environment.

[0022] In a second aspect, the present application provides a method for preparing a soil conditioner for soil acidification control in the above-mentioned scheme.

[0023] A method for preparing a soil conditioner comprises the following steps:

[0024] (1) red mud, humic acid-sodium alginate complex, zeolite, silicon calcium magnesium fertilizer, acid-resistant bacteria agent, and bio-based adhesive are mixed according to a formula to obtain a mixed raw material;

[0025] (2) placing the mixed raw materials in a granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles;

[0026] (3) Drying the conditioning agent particles obtained in step (2) to obtain the conditioning agent.

[0027] By adopting the above technical solution, soil conditioner particles can be prepared, which are convenient for application.

[0028] In a third aspect, the present application provides an application of the soil conditioner in the above scheme.

[0029] The invention discloses an application of a soil conditioner, wherein the soil conditioner is applied to the treatment of acidified soil.

[0030] In summary, this application has at least one of the following beneficial effects:

[0031] 1. The solution of this application realizes the integrated treatment of acidified soil, soil structure repair and microbial ecological reconstruction through the synergy and efficiency of multiple components. The acid treatment effect is good and durable, and it is suitable for sustainable remediation of acidic soil. DETAILED DESCRIPTION

[0032] The application is described in further detail below.

[0033] Preparation Example 1: Preparation of Humic Acid-Sodium Alginate Complex

[0034] 5 parts of humic acid (the average molecular weight of humic acid is 5000Da) are added to 100 parts of deionized water and stirred at 60°C until dissolved to obtain a humic acid solution; 5 parts of sodium alginate are added to 100 parts of deionized water and stirred at 60°C until dissolved to obtain a sodium alginate solution; the humic acid solution and the sodium alginate solution are then mixed and stirred evenly, and 1 part of polyethylene glycol is added to promote cross-linking of humic acid and sodium alginate, and stirring is continued for 1 hour; then the product is filtered and placed in an oven, dried at 50°C to constant weight, and the product is crushed and ground by a grinder and sieved to obtain a humic acid-sodium alginate complex with an average particle size of 1 mm.

[0035] Preparation Example 2: Zeolite Surface Modification

[0036] Add 1 part of 3-glycidyloxypropyltriethoxysilane to 100 parts of ethanol solution and stir. After the 3-glycidyloxypropyltriethoxysilane is dissolved, add zeolite to the obtained coupling agent solution and react for 4 hours. Then take out the zeolite, rinse it with deionized water, and then dry it for later use.

[0037] Example 1

[0038] A soil conditioner for soil acidification control is prepared by the following steps:

[0039] 1. By weight, 20 parts of red mud, 15 parts of humic acid-sodium alginate complex, 15 parts of the surface-modified zeolite prepared in Preparation Example 2, 5 parts of silicon-calcium-potassium fertilizer, 4 parts of an acid-resistant bacterial agent, and 10 parts of a bio-based adhesive were mixed to obtain a mixed raw material; wherein the acid-resistant bacterial agent was selected from phosphate-solubilizing bacteria and Bacillus subtilis, and the mass ratio of the two was 1:1, and the bio-based adhesive was selected from corn starch;

[0040] (2) placing the mixed raw material obtained in the above step in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles, wherein the mass ratio of deionized water to the mixed raw material is 1:5;

[0041] (3) The conditioner particles obtained in step (2) are placed in a forced air drying oven and dried at 60° C. for 2 h. After drying, the soil conditioner is obtained.

[0042] Example 2

[0043] A soil conditioner for soil acidification control is prepared by the following steps:

[0044] 2. By weight, 35 parts of red mud, 10 parts of humic acid-sodium alginate complex, 10 parts of the surface-modified zeolite prepared in Preparation Example 2, 8 parts of silicon-calcium-potassium fertilizer, 8 parts of an acid-resistant bacterial agent, and 15 parts of a bio-based adhesive were mixed to obtain a mixed raw material; wherein the acid-resistant bacterial agent was selected from phosphate-solubilizing bacteria and Bacillus subtilis, and the mass ratio of the two was 1:1, and the bio-based adhesive was selected from corn starch;

[0045] (2) placing the mixed raw material obtained in the above step in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles, wherein the mass ratio of deionized water to the mixed raw material is 1:5;

[0046] (3) The conditioner particles obtained in step (2) are placed in a forced air drying oven and dried at 60° C. for 2 h. After drying, the soil conditioner is obtained.

[0047] Example 3

[0048] A soil conditioner for soil acidification control is prepared by the following steps:

[0049] 3. By weight, 25 parts of red mud, 12 parts of humic acid-sodium alginate complex, 10 parts of the surface-modified zeolite prepared in Preparation Example 2, 8 parts of silicon-calcium-potassium fertilizer, 4 parts of an acid-resistant bacterial agent, 12 parts of a bio-based adhesive, and 1 part of polyglutamic acid were mixed to obtain a mixed raw material; wherein the acid-resistant bacterial agent was selected from phosphate-solubilizing bacteria and Bacillus subtilis, and the mass ratio of the two was 1:1, and the bio-based adhesive was selected from corn starch;

[0050] (2) placing the mixed raw material obtained in the above step in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles, wherein the mass ratio of deionized water to the mixed raw material is 1:5;

[0051] (3) The conditioner particles obtained in step (2) are placed in a forced air drying oven and dried at 60° C. for 2 h. After drying, the soil conditioner is obtained.

[0052] Example 4

[0053] A soil conditioner for soil acidification control is prepared by the following steps:

[0054] 4. By weight, 30 parts of red mud, 15 parts of humic acid-sodium alginate complex, 15 parts of the surface-modified zeolite prepared in Preparation Example 2, 5 parts of silicon-calcium-potassium fertilizer, 6 parts of an acid-resistant bacterial agent, 15 parts of a bio-based adhesive, and 3 parts of polyglutamic acid were mixed to obtain a mixed raw material; wherein the acid-resistant bacterial agent was selected from phosphate-solubilizing bacteria and Bacillus subtilis, and the mass ratio of the two was 1:1, and the bio-based adhesive was selected from corn starch;

[0055] (2) placing the mixed raw material obtained in the above step in a disc granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles, wherein the mass ratio of deionized water to the mixed raw material is 1:5;

[0056] (3) The conditioner particles obtained in step (2) are placed in a forced air drying oven and dried at 60° C. for 2 h. After drying, the soil conditioner is obtained.

[0057] Example 5

[0058] Compared with Example 1, this example has the same process steps and components, except that an equal amount of unmodified zeolite is used to replace the surface-modified zeolite in Example 1.

[0059] Comparative Example 1

[0060] This comparative example has the same process steps and components as Example 1, except that no zeolite is added.

[0061] Comparative Example 2

[0062] Compared with Example 1, this comparative example has the same process steps and components, except that an equal amount of humic acid is used to replace the humic acid-sodium alginate complex.

[0063] A flat outdoor site with a soil pH of 5.01 was selected and divided into multiple equal-sized areas, each isolated to prevent interference with other components, such as moisture. Each area was fertilized at a rate of 120 kg / mu, and the conditioner and soil were mixed evenly. The soil pH was then tested every three months. The soil pH values ​​after application of the conditioners of Examples 1-5 and Comparative Examples 1-2 are shown in the following table.

[0064] Table 1 pH value of soil after fertilization with the conditioners of Examples 1-5 and Comparative Examples 1-2

[0065] March (pH) June (pH) September (pH) December (pH) Example 1 6.31 6.29 6.27 6.23 Example 2 6.36 6.33 6.27 6.22 Example 3 6.45 6.41 6.40 6.38 Example 4 6.51 6.50 6.48 6.44 Example 5 6.30 6.27 6.20 6.01 Comparative Example 1 5.91 5.81 5.60 5.31 Comparative Example 2 6.45 6.01 5.92 5.31

[0066] It can be seen from the comparison of Example 1 and Example 5 that, after surface modification, zeolite can form a certain force between the surface of corn starch, can make the system more stable, and then make acid resistance more lasting. In addition, it can also be seen from the comparison of Comparison 1 and Example 2 that the humic acid-sodium alginate complex can form a cross-linked network structure in the system, can also make the release of acid-resistant components slow, thereby achieving the persistence of soil acidification management. Therefore, the soil conditioner in this application can be applied to the management of acidified soils.

[0067] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A soil conditioner for soil acidification control, characterized by: The invention comprises the following components in parts by weight: 20-35 parts of red mud, 10-15 parts of humic acid-sodium alginate complex, 10-15 parts of zeolite, 5-8 parts of silicon calcium magnesium fertilizer, 4-8 parts of acid-resistant bacteria agent, and 10-15 parts of bio-based adhesive; the humic acid-sodium alginate complex is prepared by the following method: humic acid and sodium alginate are dissolved separately, the solutions of the two are mixed, polyethylene glycol is added, the mixture is stirred continuously for reaction, and then the mixture is dried and crushed to obtain the humic acid-sodium alginate complex; the zeolite is surface-modified by an epoxy silane coupling agent; the acid-resistant bacteria agent is selected from one or more of phosphate-solubilizing bacteria, Bacillus subtilis, and Brevibacillus laterosporus.

2. A soil conditioner for soil acidification control according to claim 1, characterized in that: Calculated by weight, it also includes 1-3 parts of polyglutamic acid.

3. The soil conditioner for soil acidification control according to claim 1, characterized in that: The bio-based binder is selected from corn starch.

4. The soil conditioner for soil acidification control according to claim 1, characterized in that: The zeolite is modified by the following steps: dissolving 3-glycidyloxypropyltriethoxysilane in an ethanol solution, adding zeolite particles into the ethanol solution of 3-glycidyloxypropyltriethoxysilane, stirring for reaction, and then filtering and drying to obtain the surface-modified zeolite.

5. The method for preparing a soil conditioner for soil acidification control according to any one of claims 1 to 4, characterized in that: The following steps are included: (1) red mud, humic acid-sodium alginate complex, zeolite, silicon calcium magnesium fertilizer, acid-resistant bacteria agent, and bio-based adhesive are mixed according to a formula to obtain a mixed raw material; (2) placing the mixed raw materials in a granulator for granulation, spraying deionized water through a sprayer during the granulation process to obtain conditioning agent particles; (3) Drying the conditioning agent particles obtained in step (2) to obtain the conditioning agent.

6. Use of a soil conditioner for soil acidification control according to any one of claims 1 to 4, characterized in that: The soil conditioner is used in the treatment of acidified soil.