Modified marine facies sludge-based planting soil and preparation method thereof

Abstract

The invention relates to the field of planting soil, and discloses modified marine facies sludge-based planting soil and a preparation method thereof.The modified marine facies sludge-based planting soil is prepared by compounding marine facies sludge and a modifier according to the mass ratio of 5: 0.4-1; the modifier comprises an adsorption additive, modified polyvinyl alcohol fiber, fly ash, potassium fulvate, desulfurized gypsum and an organic fertilizer; the adsorption additive is prepared by taking straw cellulose and sodium alginate as a network framework and taking expanded vermiculite as an adsorption function unit through a metal ion cross-linking method; the modified polyvinyl alcohol fiber is prepared by oxidizing polyvinyl alcohol fiber with potassium persulfate and silver nitrate, reacting with triethylene tetramine and hydrochloric acid to generate ammonium salinized polyvinyl alcohol fiber, and further reacting with calcium bentonite acidified by hydrochloric acid. Wherein the adsorption additive and the modified polyvinyl alcohol fiber are added, so that the adsorption performance of the planting soil and the stability of soil aggregate are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of planting soil, and in particular relates to a modified marine silt-based planting soil and a preparation method thereof. Background Art

[0002] Marine silt is widely distributed in my country, almost all along the coast, in the middle and lower reaches of rivers, and near lakes. Marine silt is a structural soil composed mainly of very fine clay colloidal substances, which is deposited in still water or very slow-flowing water environments and accompanied by the action of microorganisms. The construction of engineering facilities in coastal areas will produce a large amount of waste marine silt, and the "continuously regenerated" marine silt has brought great difficulties and hidden dangers to the construction and maintenance of offshore environments and engineering facilities, and has wasted the potential application value of marine silt.

[0003] Because marine silt has high salt content, sticky texture, poor structure, low fertility indicators such as organic matter and quick-acting nutrients, after plants absorb water from the silty soil, the salt density inside and outside the plant roots is different, and the increased osmotic pressure of the soil solution can easily cause the plants to lose water and physiological drought. In addition, due to the small porosity and permeability coefficient of marine silt, its adsorption performance is poor, which makes plants easily lose water. At the same time, the increase in salt in the soil will cause the soil structure to become sticky and compacted, and the microbial activity is poor, which cannot provide favorable conditions for plant growth. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above-mentioned background technology, the purpose of the present invention is to provide a modified marine silt-based planting soil and a preparation method thereof, and to prepare a marine silt modifier using adsorption additives, modified polyvinyl alcohol fibers, fly ash, potassium humate, desulfurized gypsum and organic fertilizer as raw materials, wherein the addition of adsorption additives and modified polyvinyl alcohol fibers improves the adsorption performance of the planting soil and the stability of soil aggregates.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A modified marine sludge-based planting soil is prepared by compounding marine sludge and a modifier in a mass ratio of 5:0.4-1; the modifier comprises the following raw materials in parts by weight: 10-20 parts of an adsorption additive, 5-10 parts of modified polyvinyl alcohol fiber, 1-3 parts of fly ash, 0.5-2 parts of potassium humate, 0.5-2 parts of desulfurized gypsum, and 5-12 parts of organic fertilizer;

[0007] The adsorption additive uses straw cellulose and sodium alginate as a network framework, expanded vermiculite as an adsorption functional unit, and is made by a metal ion cross-linking method; the modified polyvinyl alcohol fiber is made by oxidizing polyvinyl alcohol fiber with potassium persulfate and silver nitrate, reacting with triethylenetetramine and hydrochloric acid to generate ammonium salt polyvinyl alcohol fiber, and then further reacting with calcium-based bentonite acidified with hydrochloric acid to make it.

[0008] Preferably, the preparation method of the adsorption additive comprises the following steps:

[0009] (1) washing, drying and crushing the straw to obtain straw powder, then adding a sodium hydroxide solution to mix, heating at 80 to 95° C. for 2 to 3 hours, cooling and filtering, washing and drying to obtain a filter residue, then adding a nitric acid solution, heating at 80 to 90° C. for 1.5 to 2 hours, cooling and filtering, washing and drying to prepare straw cellulose;

[0010] (2) Mixing sodium hydroxide solution and urea solution, cooling to -14 to -10°C to form a mixed solution, dissolving straw cellulose and sodium alginate in the mixed solution respectively, and then freezing at -14 to -10°C for 10 to 12 hours and then naturally thawing at room temperature to obtain straw solution and sodium alginate solution, then mixing the two solutions, adding expanded vermiculite and stirring thoroughly, ultrasonically degassing, and then adding anhydrous calcium chloride hydrochloric acid solution, solidifying for 42 to 48 hours, filtering, washing, and freeze-drying to prepare an adsorption additive.

[0011] Preferably, the mass concentration of the sodium hydroxide solution is 5-10%; the mass concentration of the urea solution is 10-15%; and the mass concentration of the anhydrous calcium chloride hydrochloric acid solution is 10-15%.

[0012] Preferably, the mass concentration of the straw cellulose solution and the sodium alginate solution is 2-5%.

[0013] Preferably, the method for preparing the modified polyvinyl alcohol fiber comprises the following steps:

[0014] A. Take potassium persulfate and add silver nitrate aqueous solution to mix evenly, then add polyvinyl alcohol fiber, place at 60-80° C. and stir to react for 2-5 hours. After the reaction is completed, wash and dry to prepare carboxylated polyvinyl alcohol fiber;

[0015] B. Carboxylated polyvinyl alcohol fiber, N,N'-diisopropylcarbodiimide and 1-hydroxybenzotriazole were added to N,N-dimethylformamide, and ultrasonically dispersed uniformly. Then triethylenetetramine was added, and stirred and mixed for 20 to 24 hours. After filtering and washing, the mixture was ultrasonically dispersed in deionized water, and hydrochloric acid was added dropwise under stirring and mixed for 20 to 30 minutes to prepare ammonium salt polyvinyl alcohol fiber.

[0016] C. Add 1-3 mol / L hydrochloric acid solution to calcium-based bentonite, place at 80-95° C. for reaction for 2-4 hours, cool to room temperature, centrifuge, wash, and dry to prepare acidified calcium-based bentonite;

[0017] D. Take the acidified calcium-based bentonite and ultrasonically disperse it in deionized water, stir it at 70-85°C for 0.5-1h, then add the ammonium salt polyvinyl alcohol fiber, continue to stir at constant temperature for 18-24h, and finally filter, wash and freeze-dry to prepare the modified polyvinyl alcohol fiber.

[0018] Preferably, in step B, the mass ratio of carboxylated polyvinyl alcohol fiber, N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole and triethylenetetramine is 1: 0.01-0.03: 0.01-0.03: 0.4-0.7.

[0019] Preferably, in step D, the mass ratio of the acidified calcium-based bentonite to the ammonium salted polyvinyl alcohol fiber is 1:1-2.

[0020] Preferably, the particle size of the calcium-based bentonite is 40-100 meshes; the specification of the polyvinyl alcohol fiber is 7-10 mm.

[0021] The method for preparing the modified marine silt-based planting soil as described above comprises the following steps:

[0022] S1, taking parts by weight of adsorption additive, modified polyvinyl alcohol fiber, fly ash, potassium humate, desulfurized gypsum, and organic fertilizer, stirring and mixing them evenly to obtain a modifier;

[0023] S2. Pre-treating the marine silt by turning it over and drying it until the soil is loose, and then adding a modifier and stirring and dispersing it to prepare a modified marine silt-based planting soil.

[0024] Beneficial effects of the present invention:

[0025] The present invention adopts adsorption additives, modified polyvinyl alcohol fiber, fly ash, potassium humate, desulfurized gypsum and organic fertilizer as raw materials to prepare a modifier for marine sludge, so as to change the pore structure and soil texture of modified marine sludge-based planting soil, improve the organic matter content, etc., so as to meet the relevant requirements of qualified greening planting soil. Among them, fly ash and desulfurized gypsum can effectively promote the leaching of sodium ions in the soil, reduce the content of bicarbonate ions, and increase the content of calcium ions, magnesium ions, sulfate ions and potassium ions. Potassium humate is a pure natural active potassium fertilizer, which can effectively provide nutrients for plants, maintain soil looseness and water holding capacity, adjust pH value, and can adsorb certain salt ions, which is beneficial to the growth and development of crops.

[0026] The invention uses sodium hydroxide solution and nitric acid solution to extract cellulose from straw, then uses straw cellulose and sodium alginate as a network framework, expands vermiculite as an adsorption functional unit, and adopts a metal ion cross-linking method to prepare a porous microsphere adsorption additive. Among them, straw cellulose has good toughness and porosity, which can improve soil texture. Sodium alginate is derived from brown algae kelp or seaweed. It is a biocompatible, biodegradable anionic natural polysaccharide with hydroxyl and carboxyl groups in the molecular chain. It serves as a membrane layer together with straw cellulose. The porous structure and swelling properties of expanded vermiculite give it good adsorption, water absorption and moisture retention, and air permeability. It can adsorb soluble salts and reduce the content of soluble salts in the soil. Expanded vermiculite has high sustained release and ion exchange capacity. The potassium, calcium, magnesium and other mineral nutrients it contains can be released in appropriate amounts for plants to absorb and utilize. The expanded vermiculite is loaded on the surface and inside of the adsorption additive, which produces synergistic and complementary effects with the straw cellulose and calcium alginate membrane layer, increases soil porosity, increases the adsorption sites of the adsorption additive, improves its adsorption performance, and improves plant absorption of nutrients.

[0027] The invention uses potassium persulfate as an oxidant and silver nitrate as a catalyst to perform oxidation treatment on polyvinyl alcohol fiber to prepare carboxylated polyvinyl alcohol fiber, and then reacts with triethylenetetramine and hydrochloric acid under the action of N, N'-diisopropylcarbodiimide and 1-hydroxybenzotriazole to generate ammonium salt polyvinyl alcohol fiber, and then further reacts the ammonium salt polyvinyl alcohol fiber with acidified calcium-based bentonite, wherein the calcium-based bentonite has the advantages of huge specific surface area, excellent adsorption performance, water absorption and swelling, etc., and ammonium salt cations on the surface of the polyvinyl alcohol fiber are exchanged with calcium ions and magnesium ions in the acidified calcium-based bentonite to make them enter the crystal structure of the acidified calcium-based bentonite, thereby realizing the combination of the acidified calcium-based bentonite and the polyvinyl alcohol fiber in the form of ionic bonds, and the presence of nanoparticles increases the roughness of the surface of the polyvinyl alcohol fiber, improves the connection ability of the polyvinyl alcohol fiber, is more conducive to the connection of the polyvinyl alcohol fiber with soil single particles to form large aggregates, and improves the soil structure. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1 A method for preparing an adsorption additive comprises the following steps:

[0030] (1) 100 g corn stalks were washed, dried, and crushed to obtain stalk powder, and then a 2.5 mol / L sodium hydroxide solution was added and mixed, and the mixture was heated at 90° C. for 2 h, cooled and filtered, washed and dried to obtain a filter residue, and then a 4 mol / L nitric acid solution was added, and the mixture was heated at 80° C. for 2 h, cooled and filtered, washed and dried to obtain stalk cellulose;

[0031] (2) A sodium hydroxide solution with a mass concentration of 7% and a urea solution with a mass concentration of 12% were mixed, cooled to -12°C to form a mixed solution, 10 g of straw cellulose and 10 g of sodium alginate were dissolved in 500 mL of the mixed solution respectively, and then frozen at -12°C for 12 hours and naturally thawed at room temperature to obtain a straw solution and a sodium alginate solution, and then the two solutions were mixed, 5 g of expanded vermiculite was added and stirred thoroughly, ultrasonically degassed, and then a hydrochloric acid solution of anhydrous calcium chloride with a mass concentration of 12% was added, and the mixture was solidified for 48 hours. After filtering, washing, and freeze-drying, an adsorption additive was prepared.

[0032] Embodiment 2 A method for preparing a modified polyvinyl alcohol fiber comprises the following steps:

[0033] A. Take 3.5 g of potassium persulfate and add 0.002 g / mL of silver nitrate aqueous solution to mix evenly, then add polyvinyl alcohol fiber, place at 75 ° C. and stir to react for 5 hours. After the reaction is completed, wash and dry to prepare carboxylated polyvinyl alcohol fiber;

[0034] B. Take 5g of carboxylated polyvinyl alcohol fiber, 0.1g of N, N'-diisopropylcarbodiimide and 0.1g of 1-hydroxybenzotriazole, add 250mL of N, N-dimethylformamide, and disperse them evenly by ultrasonication. Then add 2.5g of triethylenetetramine, stir and mix for 24h, filter and wash, and then disperse them by ultrasonication in 250mL of deionized water. Then, add 14mL of hydrochloric acid dropwise and mix for 30min under stirring to prepare ammonium salt polyvinyl alcohol fiber.

[0035] C. Take 5 g of calcium-based bentonite and add 50 mL of 1 mol / L hydrochloric acid solution, place at 85° C. for 4 h, cool to room temperature, centrifuge, wash, and dry to prepare acidified calcium-based bentonite;

[0036] D. Take 5 g of acidified calcium-based bentonite and ultrasonically disperse it in 100 mL of deionized water, stir it at 85°C for 0.5 h, then add 5 g of ammonium salted polyvinyl alcohol fiber, continue to stir at constant temperature for 24 h, and finally filter, wash, and freeze-dry to prepare modified polyvinyl alcohol fiber.

[0037] Example 3 A modified marine silt-based planting soil is prepared by compounding marine silt and a modifier in a mass ratio of 5:1; the modifier includes the following raw materials in parts by weight: 10 parts of the adsorption additive prepared in Example 1, 5 parts of modified polyvinyl alcohol fiber prepared in Example 2, 1.5 parts of fly ash, 0.5 parts of potassium humate, 0.7 parts of desulfurized gypsum, and 8 parts of decomposed chicken manure as an organic fertilizer.

[0038] The method for preparing the modified marine silt-based planting soil comprises the following steps:

[0039] S1, taking parts by weight of adsorption additive, modified polyvinyl alcohol fiber, fly ash, potassium humate, desulfurized gypsum, and organic fertilizer, stirring and mixing them evenly to obtain a modifier;

[0040] S2. Pre-treating the marine silt by turning it over and drying it until the soil is loose, and then adding a modifier and stirring and dispersing it to prepare a modified marine silt-based planting soil.

[0041] Example 4 A modified marine silt-based planting soil is prepared by compounding marine silt and a modifier in a mass ratio of 5:0.7; the modifier includes the following raw materials in parts by weight: 15 parts of the adsorption additive prepared in Example 1, 7 parts of modified polyvinyl alcohol fiber prepared in Example 2, 2 parts of fly ash, 1 part of potassium humate, 1.2 parts of desulfurized gypsum, and 10 parts of decomposed chicken manure as an organic fertilizer.

[0042] The preparation method of the above-mentioned modified marine silt-based planting soil is the same as that in Example 3.

[0043] Example 5 A modified marine silt-based planting soil is prepared by compounding marine silt and a modifier in a mass ratio of 1:0.1; the modifier includes the following raw materials in parts by weight: 18 parts of the adsorption additive prepared in Example 1, 10 parts of modified polyvinyl alcohol fiber prepared in Example 2, 3 parts of fly ash, 2 parts of potassium humate, 2 parts of desulfurized gypsum, and 11 parts of decomposed chicken manure as an organic fertilizer.

[0044] The preparation method of the above-mentioned modified marine silt-based planting soil is the same as that in Example 3.

[0045] Comparative Example 1 A modified marine silt-based planting soil is prepared by compounding marine silt and a modifier in a mass ratio of 1:0.1; the modifier includes the following raw materials in parts by weight: 12 parts of corn stalks, 6 parts of expanded vermiculite, 10 parts of modified polyvinyl alcohol fibers prepared in Example 2, 3 parts of fly ash, 2 parts of potassium humate, 2 parts of desulfurized gypsum, and 11 parts of decomposed chicken manure as an organic fertilizer.

[0046] The preparation method of the above-mentioned modified marine silt-based planting soil is the same as that in Example 3.

[0047] Comparative Example 2: A modified marine silt-based planting soil, which is prepared by compounding marine silt and a modifier in a mass ratio of 1:0.1; the modifier includes the following raw materials in parts by weight: 18 parts of the adsorption additive prepared in Example 1, 10 parts of polyvinyl alcohol fiber, 3 parts of fly ash, 2 parts of potassium humate, 2 parts of desulfurized gypsum, and 11 parts of decomposed chicken manure as an organic fertilizer.

[0048] The preparation method of the above-mentioned modified marine silt-based planting soil is the same as that in Example 3.

[0049] Performance Testing

[0050] (1) The modified marine silt-based planting soil prepared in Examples 3-5 was subjected to heavy metal toxicity leaching detection, the leaching solution was acetic acid solution (pH value was 4.93±0.05), and the leaching solution was Class I to III water (Surface Water Environmental Quality Standards), and the data results were shown in Table 1; a variable head permeability test was conducted at room temperature of 20°C to test the permeability coefficients of the modified marine silt-based planting soil prepared in Examples 3-5 and Comparative Examples 1-2, and the average weight diameter and 0.25 mm particle size aggregate content were detected. The number of soil aggregates can represent the stability of the soil aggregate structure to a certain extent. The larger the number, the more stable the soil aggregate structure. The data results are shown in Table 2.

[0051] Table 1 Heavy metal toxicity leaching test results of samples

[0052]

[0053] It can be seen from the data in Table 1 that the leaching concentrations of heavy metals in the modified marine silt-based planting soils prepared in Examples 3-5 of the present invention are reduced to varying degrees, and the stability of heavy metals is improved.

[0054] Table 2 Test results of sample performance

[0055]

[0056] From the data results in Table 2, it can be seen that the modified marine silt-based planting soil prepared in Examples 3-5 of the present invention has an increased permeability coefficient and total porosity compared with Comparative Examples 1-2, and the average weight diameter and 0.25 mm particle size aggregate content are both improved, thereby enhancing the stability of soil aggregates. In Comparative Example 1, the adsorption additive is replaced with a simple mixture of corn stalks and expanded vermiculite, and the measured permeability coefficient and total porosity are lower than those of Examples 3-5, indicating that the addition of the adsorption additive can improve the adsorption effect of the planting soil. In Comparative Example 2, the polyvinyl alcohol fiber is not modified, and the measured permeability coefficient, average weight diameter, 0.25 mm particle size aggregate content and total porosity are lower than those of Examples 3-5, indicating that the modification of the polyvinyl alcohol fiber can improve the connection ability of the polyvinyl alcohol fiber and improve the stability of the soil aggregates.

[0057] (2) Cold-resistant kale seedlings with a short growth cycle were selected as the research object of plant performance. The modified marine silt-based planting soil prepared in Examples 3-5 and Comparative Examples 1-2 were used to plant 2 pots, for a total of 10 pots, with 1 kale plant in each pot. In order to ensure sufficient sunlight and stable day and night temperatures, the planting was carried out in a 2m×2m transparent flower shed. The data results obtained after 60 days of planting are shown in Table 3.

[0058] Table 3 Specimen planting test results

[0059]

[0060] It can be seen from the data results in Table 3 that the average plant height, stem and leaf weight and root length of the plants cultivated in the modified marine silt-based planting soil prepared in Examples 3-5 of the present invention are better than those in Comparative Examples 1-2.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0062] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A modified marine silt-based planting soil, characterized in that: The invention is prepared by compounding marine sludge and a modifier in a mass ratio of 5:0.4-1; the modifier comprises the following raw materials in parts by weight: 10-20 parts of adsorption additive, 5-10 parts of modified polyvinyl alcohol fiber, 1-3 parts of fly ash, 0.5-2 parts of potassium humate, 0.5-2 parts of desulfurized gypsum, and 5-12 parts of organic fertilizer; The adsorption additive uses straw cellulose and sodium alginate as a network framework, expanded vermiculite as an adsorption functional unit, and is made by a metal ion cross-linking method; the modified polyvinyl alcohol fiber is made by oxidizing polyvinyl alcohol fiber with potassium persulfate and silver nitrate, reacting with triethylenetetramine and hydrochloric acid to generate ammonium salt polyvinyl alcohol fiber, and then further reacting with calcium-based bentonite acidified with hydrochloric acid to make it.

2. The modified marine silt-based planting soil according to claim 1, characterized in that: The preparation method of the adsorption additive comprises the following steps: (1) washing, drying and crushing the straw to obtain straw powder, then adding a sodium hydroxide solution to mix, heating at 80 to 95° C. for 2 to 3 hours, cooling and filtering, washing and drying to obtain a filter residue, then adding a nitric acid solution, heating at 80 to 90° C. for 1.5 to 2 hours, cooling and filtering, washing and drying to prepare straw cellulose; (2) Mixing sodium hydroxide solution and urea solution, cooling to -14 to -10°C to form a mixed solution, dissolving straw cellulose and sodium alginate in the mixed solution respectively, and then freezing at -14 to -10°C for 10 to 12 hours and then naturally thawing at room temperature to obtain straw solution and sodium alginate solution, then mixing the two solutions, adding expanded vermiculite and stirring thoroughly, ultrasonically degassing, and then adding anhydrous calcium chloride hydrochloric acid solution, solidifying for 42 to 48 hours, filtering, washing, and freeze-drying to prepare an adsorption additive.

3. The modified marine silt-based planting soil according to claim 2, characterized in that: The mass concentration of the sodium hydroxide solution is 5-10%; the mass concentration of the urea solution is 10-15%; and the mass concentration of the anhydrous calcium chloride hydrochloric acid solution is 10-15%.

4. The modified marine silt-based planting soil according to claim 2, characterized in that: The mass concentration of the straw cellulose solution and the sodium alginate solution is 2-5%.

5. The modified marine silt-based planting soil according to claim 1, characterized in that: The preparation method of the modified polyvinyl alcohol fiber comprises the following steps: A. Take potassium persulfate and add silver nitrate aqueous solution to mix evenly, then add polyvinyl alcohol fiber, place at 60-80° C. and stir to react for 2-5 hours. After the reaction is completed, wash and dry to prepare carboxylated polyvinyl alcohol fiber; B. Carboxylated polyvinyl alcohol fiber, N,N'-diisopropylcarbodiimide and 1-hydroxybenzotriazole were added to N,N-dimethylformamide, and ultrasonically dispersed uniformly. Then triethylenetetramine was added, and stirred and mixed for 20 to 24 hours. After filtering and washing, the mixture was ultrasonically dispersed in deionized water, and hydrochloric acid was added dropwise under stirring and mixed for 20 to 30 minutes to prepare ammonium salt polyvinyl alcohol fiber. C. Add 1-3 mol / L hydrochloric acid solution to calcium-based bentonite, place at 80-95° C. for reaction for 2-4 hours, cool to room temperature, centrifuge, wash, and dry to prepare acidified calcium-based bentonite; D. Take the acidified calcium-based bentonite and ultrasonically disperse it in deionized water, stir it at 70-85°C for 0.5-1h, then add the ammonium salt polyvinyl alcohol fiber, continue to stir at constant temperature for 18-24h, and finally filter, wash and freeze-dry to prepare the modified polyvinyl alcohol fiber.

6. The modified marine silt-based planting soil according to claim 5, characterized in that: In the step B, the mass ratio of the carboxylated polyvinyl alcohol fiber, N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole and triethylenetetramine is 1:0.01-0.03:0.01-0.03:0.4-0.

7.

7. The modified marine silt-based planting soil according to claim 5, characterized in that: In the step D, the mass ratio of the acidified calcium-based bentonite to the ammonium salted polyvinyl alcohol fiber is 1:1-2.

8. The modified marine silt-based planting soil according to claim 5, characterized in that: The particle size of the calcium-based bentonite is 40-100 meshes; the specification of the polyvinyl alcohol fiber is 7-10 mm.

9. A method for preparing modified marine silt-based planting soil according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, taking parts by weight of adsorption additive, modified polyvinyl alcohol fiber, fly ash, potassium humate, desulfurized gypsum, and organic fertilizer, stirring and mixing them evenly to obtain a modifier; S2. Pre-treating the marine silt by turning it over and drying it until the soil is loose, and then adding a modifier and stirring and dispersing it to prepare a modified marine silt-based planting soil.

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