Composite repairing agent suitable for saline-alkali soil

Abstract

A composite restoration agent suitable for saline-alkali soil belongs to the technical field of saline-alkali soil restoration, and comprises, by mass, 55-60% of phosphogypsum, 2-3% of furfural residue, 6-10% of coal granular activated carbon, 3-5% of basalt nanofiber, 8-12% of mineral potassium fulvate, 13-15% of humic acid, 3-5% of oligosaccharide, 1-1.5% of gamma-polyglutamic acid, and 1-1.5% of a microbial agent. By applying the composite repairing agent, the pH value and the conductivity of the soil can be reduced, and the crop yield can be increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of saline-alkali soil remediation, and relates to a composite remediation agent suitable for saline-alkali soil. BACKGROUND

[0002] The saline-alkali soil in China has the characteristics of high soil bulk density, low porosity, poor water permeability, pH 8.5-10.5, high alkalization degree, and high content of Na2CO3 and NaHCO3. +

[0003] At present, the saline-alkali soil treatment includes the following aspects: 1. Deep ploughing improvement: the saline-alkali soil is ploughed to about 30-40 cm, so as to improve the soil structure.

[0004] 2. Water washing improvement: the salt is removed by irrigation and drainage.

[0005] 3. Chemical improvement: inorganic improvement agents (such as desulfurized gypsum, aluminum sulfate, etc.) and / or organic improvement agents (such as polyacrylamide, furfural residue, etc.) are applied to the soil, so as to improve the soil.

[0006] 4. Microbial improvement: functional microbial agents (such as photosynthetic bacteria, nitrogen-fixing bacteria, rhizobium, streptomyces, etc.) are applied to the soil, so as to improve the soil environment and maintain the soil microbial balance.

[0007] At present, most of the saline-alkali soil improvement methods choose a single improvement method, and the saline-alkali soil improvement is concentrated on the surface treatment, so it is necessary to further study the saline-alkali soil improvement and remediation. SUMMARY

[0008] The application aims to provide a composite remediation agent suitable for saline-alkali soil, which can remediate the saline-alkali soil, reduce the soil pH value and conductivity, and improve the crop yield.

[0009] The application adopts the following technical scheme to achieve the above-mentioned purpose: The composite remediation agent suitable for saline-alkali soil includes, by mass percentage, 55-60% of phosphogypsum, 2-3% of furfural residue, 6-10% of coal-based granular activated carbon, 3-5% of basalt nanofiber, 8-12% of mineral-derived potassium fulvic acid, 13-15% of humic acid, 3-5% of oligosaccharide, 1-1.5% of gamma-polyglutamic acid, and 1-1.5% of microbial agent.

[0010] ​A further technical solution involves the oligosaccharide comprising fructooligosaccharides, xylooligosaccharides, and sodium alginate oligosaccharides in a mass ratio of 1:1:2. Fructooligosaccharides specifically stimulate the growth of beneficial bacteria in the soil, improving the soil microenvironment through a quorum effect. Xylooligosaccharides, as a high-quality carbon source for beneficial bacteria such as Bacillus and lactic acid bacteria, can be rapidly utilized, thereby promoting the proliferation of beneficial bacteria, facilitating the analysis of organic acids, neutralizing soil alkalinity, and improving the soil environment. Sodium alginate oligosaccharides can stimulate microorganisms to secrete extracellular polysaccharides (EPS), thereby promoting soil aggregate formation and improving soil porosity. The combined use of these three components achieves the effect of improving the soil microenvironment and regulating soil structure.

[0011] A further technical solution involves the microbial agent comprising Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus mucilaginosus in a mass ratio of 3:1:1. Bacillus amyloliquefaciens and Bacillus mucilaginosus are responsible for phosphorus and potassium solubilization and secretion of organic acids; Bacillus subtilis can improve the soil microecology, and its produced antibiotics can inhibit or eliminate harmful bacteria. The large dosage of Bacillus subtilis is used to first improve the soil microenvironment, providing a favorable working environment for Bacillus amyloliquefaciens and Bacillus mucilaginosus, which is conducive to their better performance, promoting nitrogen fixation by Bacillus mucilaginosus, and forming a healthy soil ecological environment.

[0012] In a further technical solution, the coal-based granular activated carbon is first acid-washed and then loaded in a calcium chloride solution.

[0013] A further technical solution is that the composite repair agent is a granule, and the preparation method is as follows: S1. The coal-based granular activated carbon is first acid washed, then soaked in calcium chloride solution for more than 12 hours, and then mixed with phosphogypsum, furfural residue, basalt nanofiber, mineral potassium humate and humic acid to obtain a mixture. S2. Add oligosaccharides, γ-polyglutamic acid, and microbial agents to water to form a mixture; S3. Add the mixture, liquid, and binder to a granulator for granulation to obtain a composite repair agent.

[0014] A further technical solution involves step S1, where the coal-based granular activated carbon is soaked in a 1 mol / L hydrochloric acid solution for 2-4 hours, then washed until neutral, mixed in an 8-12% calcium chloride solution, and placed in a vacuum dryer under vacuum (e.g., -0.1 MPa) for 15-30 minutes. By soaking the coal-based granular activated carbon in hydrochloric acid for acid modification, oxygen-containing functional groups can be introduced onto the surface of the activated carbon, thereby effectively adsorbing sodium ions from the soil through electrostatic interactions. Furthermore, by loading calcium ions into the activated carbon, calcium ions can be continuously exchanged for sodium ions in the soil, thus improving the sodium ion content in the soil over a long period.

[0015] In a further technical solution, in step S2, the amount of water added is 3 to 5 times the total amount of oligosaccharides, γ-polyglutamic acid, and microbial agents.

[0016] In a further technical solution, in step S3, the adhesive is sodium carboxymethyl cellulose.

[0017] The beneficial effects of this invention are: This invention utilizes phosphogypsum and furfural residue as the main components for chemical improvement. The calcium ions in the phosphogypsum displace sodium ions from the soil, while the strong acidity of the furfural residue neutralizes the soil's alkalinity. The addition of basalt nanofibers enhances the soil's skeletal structure, reducing soil erosion and compaction, and promoting the sequestration of soil organic carbon (SOC). Coal-based granular activated carbon adsorbs salt ions and harmful substances from the soil and serves as a habitat for microorganisms, providing long-term improvement. The combined use of these two components constructs water-air channels, improving soil permeability. The combined use of mineral-derived potassium humate and humic acid achieves both rapid and long-lasting effects, adding organic matter to the soil, promoting soil aggregate formation, and nourishing the soil ecosystem. Oligosaccharides, γ-polyglutamic acid, and microbial agents act as bioactivators, providing long-term repair and nutrient conversion, jointly promoting the secretion of organic acids and EPS, creating healthy soil. Attached Figure Description

[0018] Figure 1 This is a graph showing the changes in soil pH.

[0019] Figure 2 This is a graph showing the change in soil electrical conductivity. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] Example 1 The composite remediation agent suitable for saline-alkali land, by weight percentage, includes 57% phosphogypsum, 2% furfural residue, 7% coal-based granular activated carbon (acid-treated and calcium-loaded), 5% basalt nanofibers, 10% mineral-derived potassium humate, 13% humic acid, 0.75% fructooligosaccharides, 0.75% xylooligosaccharides, 1.5% sodium alginate oligosaccharides, 1.5% γ-polyglutamic acid, 0.9% Bacillus subtilis, 0.3% Bacillus amyloliquefaciens, and 0.3% Bacillus mucilaginosus.

[0022] Example 2 The composite remediation agent suitable for saline-alkali land, by weight percentage, includes 57% phosphogypsum, 3% furfural residue, 9% coal-based granular activated carbon (acid-treated and calcium-loaded), 3% basalt nanofibers, 8% mineral-derived potassium humate, 14% humic acid, 1% fructooligosaccharides, 1% xylooligosaccharides, 2% sodium alginate oligosaccharides, 1% γ-polyglutamic acid, 0.6% Bacillus subtilis, 0.2% Bacillus amyloliquefaciens, and 0.2% Bacillus mucilaginosus.

[0023] Example 3 The composite remediation agent suitable for saline-alkali land, by weight percentage, includes 58% phosphogypsum, 2% furfural residue, 7% coal-based granular activated carbon (acid-treated and calcium-loaded), 4% basalt nanofibers, 11% mineral-derived potassium humate, 13% humic acid, 0.75% fructooligosaccharides, 0.75% xylooligosaccharides, 1.5% sodium alginate oligosaccharides, 1% γ-polyglutamic acid, 0.6% Bacillus subtilis, 0.2% Bacillus amyloliquefaciens, and 0.2% Bacillus mucilaginosus.

[0024] Example 4 The composite remediation agent suitable for saline-alkali land, by weight percentage, includes 56% phosphogypsum, 2% furfural residue, 10% coal-based granular activated carbon (acid-treated and calcium-loaded), 3% basalt nanofibers, 9% mineral-derived potassium humate, 13% humic acid, 1% fructooligosaccharides, 1% xylooligosaccharides, 2% sodium alginate oligosaccharides, 1.5% γ-polyglutamic acid, 0.9% Bacillus subtilis, 0.3% Bacillus amyloliquefaciens, and 0.3% Bacillus mucilaginosus.

[0025] Example 5 The composite repair agent described in Examples 1-4 is a granule form, and its preparation method is as follows: S1. Soak coal-based granular activated carbon in a 1 mol / L hydrochloric acid solution for 3 hours, then wash until neutral, mix in a 10% calcium chloride solution, place in a vacuum dryer and evacuate (-0.1 MPa) for 20 minutes, then mix with phosphogypsum, furfural residue, basalt nanofibers, mineral-derived potassium humate, and humic acid to obtain a mixture. S2. Add oligosaccharides, γ-polyglutamic acid, and microbial agents to 4 times the amount of water to form a mixture (to act as a wetting agent, fine-tune the amount of water by ensuring it clumps together when squeezed but crumbles easily when touched). S3. The mixture, along with the liquid and the binder sodium carboxymethyl cellulose, is added to a granulator for granulation and then dried at low temperature to obtain a composite repair agent.

[0026] Comparative Example 1 By weight percentage, it includes 57% phosphogypsum, 3% furfural residue, 9% coal-based granular activated carbon (commercially available, untreated and unloaded with calcium), 3% basalt nanofibers, 8% mineral-derived potassium humate, 14% humic acid, 1% fructooligosaccharides, 1% xylooligosaccharides, 2% sodium alginate oligosaccharides, 1% γ-polyglutamic acid, 0.6% Bacillus subtilis, 0.2% Bacillus amyloliquefaciens, and 0.2% Bacillus jellyii.

[0027] Comparative Example 2 By weight percentage, it includes 57% phosphogypsum, 3% furfural residue, 9% coal-based granular activated carbon (acid-treated and calcium-loaded), 3% basalt nanofibers, 8% mineral-derived potassium humate, 14% humic acid, 4% glucose, 1% γ-polyglutamic acid, 0.6% Bacillus subtilis, 0.2% Bacillus amyloliquefaciens, and 0.2% Bacillus jellyii.

[0028] Experimental Example 1: Laboratory Experimental Design 1.1 Soil Testing 30 kg of saline-alkali soil was taken and its pH was measured to be 9.1, electrical conductivity 4.4 mS / cm, alkalinity 34.9%, and bulk density 1.58 g / cm³. 3 .

[0029] 1.2 Experimental Design Six treatment groups were set up, namely, adding the composite repair agent of Example 1 (treatment 1), adding the composite repair agent of Example 2 (treatment 2), adding the composite repair agent of Example 3 (treatment 3), adding the composite repair agent of Example 4 (treatment 4), adding the composite repair agent of Comparative Example 1 (treatment 5), and adding the composite repair agent of Comparative Example 2 (treatment 6).

[0030] Each group of soil was placed in a flowerpot with a thickness of 20cm. The amount of compound repair agent added was 6g. The pots were placed in a well-ventilated outdoor area for 30 days. During this period, there was no rain, but the soil was kept moist without water accumulation (maintaining the soil's maximum water holding capacity of 60%~70%). The soil was turned over every 5 days, and soil samples from each group were taken for testing every 10 days.

[0031] 1.3 Experimental Results and Analysis See Figure 1The graph shows the changes in soil pH. As can be seen from the graph, the pH of the soils treated with the compound remediation agent decreased to varying degrees. After 30 days of treatment, treatments 1-4 reduced the soil pH from 9.1 to approximately 7.4.

[0032] See Figure 2 The graph shows the changes in soil electrical conductivity. As can be seen from the graph, the electrical conductivity decreases to varying degrees over time, dropping to approximately 2.9 mS / cm after about 30 days. It is expected that combining irrigation, salt removal, and deep plowing can further reduce the electrical conductivity.

[0033] Experimental Example 2: Field Experiment An experiment was conducted on saline-alkali land in Hohhot, Inner Mongolia Autonomous Region. Five plots were established: a control group and a group treated with the composite remediation agents described in Examples 1-4. The soil was deep-plowned, and 150 kg / mu of the composite remediation agent was applied. One month after remediation, silage corn was planted, with the composite remediation agent applied as a base fertilizer. Irrigation was used to suppress salt deposits. Field management, including sowing and fertilization, followed standard field management practices. After harvest, yield was recorded, and soil samples were collected. A 60 cm deep soil profile was excavated in each plot, and undisturbed soil samples from the 0-10 cm, 10-20 cm, 20-40 cm, and 40-60 cm layers were brought back to the laboratory, with approximately 700 g collected from each layer. After air-drying at room temperature, the soil was broken into small clods of about 1 cm along natural cracks. Stones and roots were removed, and the soil was sieved through an 8 mm sieve for aggregate separation (particle sizes >0.25 mm, 0.25-0.053 mm, and <0.053 mm).

[0034] As shown in Table 1, the application of compound remediation agent can increase the yield of silage corn, indicating that the compound remediation agent has achieved a certain degree of soil remediation and improvement, making it more suitable for crop growth and development.

[0035] Note: The experimental group is the average of Examples 1-4.

[0036] Table 2 shows that large aggregates (>0.25mm) accounted for a large proportion in the 0-10cm and 10-20cm soil layers. The proportion of large aggregates further increased in the soil treated with the remediation agent. Overall, the proportion of large aggregates decreased with increasing soil depth, but the proportion of large aggregates in the soil treated with the remediation agent was still higher than that in the control group. This indicates that the composite remediation agent of the present invention can improve soil aggregation and increase porosity.

[0037] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A composite remediation agent suitable for saline-alkali land, characterized in that, By mass percentage, it includes 55-60% phosphogypsum, 2-3% furfural residue, 6-10% coal-based granular activated carbon, 3-5% basalt nanofibers, 8-12% mineral-derived potassium humate, 13-15% humic acid, 3-5% oligosaccharides, 1-1.5% γ-polyglutamic acid, and 1-1.5% microbial inoculant.

2. The composite remediation agent suitable for saline-alkali land according to claim 1, characterized in that, The oligosaccharides include fructooligosaccharides, xylooligosaccharides, and sodium alginate oligosaccharides in a mass ratio of 1:1:

2.

3. The composite remediation agent suitable for saline-alkali land according to claim 1, characterized in that, The microbial agent includes Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus colloidis in a mass ratio of 3:1:

1.

4. The composite remediation agent suitable for saline-alkali land according to claim 1, characterized in that, The coal-based granular activated carbon is first acid-washed and then loaded in a calcium chloride solution.

5. The composite remediation agent suitable for saline-alkali land according to claim 1, characterized in that, The composite repair agent is in granule form, and its preparation method is as follows: S1. The coal-based granular activated carbon is first acid washed, then soaked in calcium chloride solution for more than 12 hours, and then mixed with phosphogypsum, furfural residue, basalt nanofiber, mineral potassium humate and humic acid to obtain a mixture. S2. Add oligosaccharides, γ-polyglutamic acid, and microbial agents to water to form a mixture; S3. Add the mixture, liquid, and binder to a granulator for granulation to obtain a composite repair agent.

6. The composite remediation agent suitable for saline-alkali land according to claim 5, characterized in that, In step S1, the coal-based granular activated carbon is treated by soaking it in a 1 mol / L hydrochloric acid solution for 2-4 hours, then washing it until neutral, mixing it in an 8-12% calcium chloride solution, and then placing it in a vacuum dryer to be vacuumed and kept there for 15-30 minutes.

7. The composite remediation agent suitable for saline-alkali land according to claim 5, characterized in that, In step S2, the amount of water added is 3 to 5 times the total amount of oligosaccharides, γ-polyglutamic acid, and microbial agents.

8. The composite remediation agent suitable for saline-alkali land according to claim 5, characterized in that, In step S3, the binder is sodium carboxymethyl cellulose.

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