Potamogeton crispus-based soil improvement composition and preparation method thereof

Abstract

The invention relates to the field of soil improvement agents, in particular to a potamogeton crispus-based soil improvement composition and a preparation method thereof. The potamogeton crispus-based soil improvement composition comprises the following raw materials: a potamogeton crispus treatment composition, a composite functional material, a water retention and nutrient slow release agent, a passivating agent and the like. According to the method, the potamogeton crispus is effectively pretreated and converted, on the basis of simplifying existing treatment steps, the application effect of the potamogeton crispus in the soil improvement composition is greatly improved, the actual improvement effect of the potamogeton crispus-based soil improvement composition can be effectively improved through formula combination, and the phenomena of corrosion and phase separation during storage are avoided; therefore, cyclic utilization of aquatic plant waste is achieved, the existing environmental protection requirement is met, and meanwhile a good comprehensive application function is provided.

Description

Technical Field

[0001] This application relates to the field of soil conditioners, and more specifically, to a Potamogeton crispus-based soil improvement composition and a preparation method thereof. Background Art

[0002] Potamogeton crispus, also known as shrimp algae and shrimp grass, is a submerged plant widely distributed in freshwater lakes and ponds. It plays an important role in the ecosystem. It is not only one of the primary producers but also has a positive effect on water purification. Potamogeton crispus can absorb nutrients such as nitrogen and phosphorus in water bodies, helping to reduce the phenomenon of water eutrophication. In addition, due to its characteristics of rapid growth and easy harvesting, Potamogeton crispus shows potential in bioremediation and resource recovery.

[0003] In recent years, with the enhancement of environmental awareness and the development of technology, people have begun to explore the possibility of using aquatic plants such as Potamogeton crispus for soil improvement. Research shows that Potamogeton crispus contains rich organic matter, minerals and other beneficial components, which can improve soil structure, increase soil fertility and promote microbial activity. Specifically, after appropriate treatment, Potamogeton crispus can be transformed into an effective soil conditioner for improving soil water retention capacity, enhancing soil aeration and optimizing soil pH value, etc.

[0004] Currently, several studies and practices have attempted to use aquatic plant waste to make soil conditioners, including the application of Potamogeton crispus. However, there are still some limitations in the existing technology. For example, due to the large differences in nutrient content of Potamogeton crispus from different sources, the quality of the prepared soil conditioners is uneven, affecting the actual application effect; it is easy to rot and phase-separate during storage, and the previous methods often require complex processing steps to transform Potamogeton crispus into a soil conditioner, which increases costs and limits large-scale application. Finally, most Potamogeton crispus improvement compositions focus on single functions (such as only adjusting pH or providing organic matter), lacking the ability to synergistically regulate soil structure, microbial activity and pollution remediation. Summary of the Invention

[0005] Therefore, in order to effectively solve the above existing problems, this application provides a Potamogeton crispus-based soil improvement composition and a preparation method thereof. Through effective pretreatment and transformation of Potamogeton crispus, on the basis of simplifying the existing treatment steps, the application effect of Potamogeton crispus in the soil improvement composition is greatly improved, and the actual improvement effect of the Potamogeton crispus-based soil improvement composition can be effectively improved through formula combination, and the rotting and phase-separation phenomena during storage can be avoided, thus realizing the recycling of aquatic plant waste, meeting the existing environmental protection requirements, and also providing good comprehensive application functions.

[0006] A Potamogeton crispus-based soil improvement composition, by mass, the raw materials are composed of the following components: 40-60 parts of Potamogeton crispus treatment composition, 20-30 parts of composite functional material, 4-6 parts of water retaining agent, 5-8 parts of nutrient slow release agent, 3-5 parts of passivator, 3-4 parts of microbial activator, 2-10 parts of solid powder, and 2-3 parts of regulator.

[0007] As a preferred embodiment, the mass ratio of the Potamogeton crispus treatment composition, the composite functional material and the solid powder is (45-55):(22-26):(5-10).

[0008] As a preferred embodiment, the mass ratio of the Potamogeton crispus treatment composition, the composite functional material and the solid powder is (48-52):(24-25):(8-9).

[0009] As a preferred embodiment, the preparation method of the Potamogeton crispus treatment composition specifically includes the following steps: S1: Wash Potamogeton crispus, cut it into sections and crush it to a particle size, then mix it with cellulase and add deionized water, and keep it warm for 3-4 h; S2: After completion, mix the product of S1 with a composite bacterial agent, adjust the pH and ferment for 7-8 days, turning it over every day; S3: Add a mixture of brown sugar and fish meal, maintain the humidity and let it stand and ferment for 5-6 days; S4: After hot air drying, crush it to and mix it with nano-silica, heat up and activate it, and it is obtained after completion.

[0010] As a preferred embodiment, the preparation method of the Potamogeton crispus treatment composition specifically includes the following steps: S1: Wash Potamogeton crispus with a high-pressure water gun, cut it into sections ≤5 cm, crush it to a particle size ≤2 mm, then mix the crushed Potamogeton crispus with cellulase, add deionized water and keep it warm at 50-55 °C for 3-4 h; S2: After completion, mix the product of S1 with a composite bacterial agent, adjust the pH to 6.5-7, ferment at 45 °C for 7-8 days, turning it over every day; S3: Add a mixture of brown sugar and fish meal, maintain the humidity at 60-65%, let it stand and ferment at 50-55 °C for 5-6 days; S4: Hot air dry at 80-85 °C until the moisture content ≤3%, crush it to 200-300 mesh and mix it with nano-silica, activate it at 60-65 °C for 2-3 h, and it is obtained after completion.

[0011] As a preferred embodiment, the dosage of the cellulase is 0.3-0.5 wt% of the dosage of Potamogeton crispus, the enzyme activity ≥5000 U / g, and the mass ratio of Potamogeton crispus and deionized water is 1:(2-3).

[0012] As a preferred embodiment, the mass ratio of the product of S1 and the composite bacterial agent is 100:(5-6).

[0013] As a preferred embodiment, the compound microbial agent is a combination of Bacillus subtilis, actinomycetes and Trichoderma viride, and the mass ratio is (2-3):(1-1.5):(1-1.5). The total bacterial count of the compound microbial agent is (1-2)×10 8 CFU / g.

[0014] As a preferred embodiment, in the mixture of brown sugar and fish meal, the mass ratio of brown sugar to fish meal is (3-4):1.

[0015] As a preferred embodiment, the addition amount of the nano-silica is 0.4-0.5 wt%.

[0016] By preparing and adding the Potamogeton crispus treatment composition into the improved composition, the various properties of the improved composition can be greatly improved. The Potamogeton crispus treatment composition releases cellulose and hemicellulose through enzymatic hydrolysis and cell wall breaking. After fermentation, the humic acid content is greatly increased, which can directly improve the soil fertility. Moreover, it can form stable complexes with heavy metals through its abundant carboxyl and phenolic hydroxyl groups, reducing the harmful effects. On the other hand, in this application, the "enzymatic hydrolysis + compound microbial agent + directional fermentation" process greatly improves the humic acid generation efficiency in the composition, and the lower activation temperature can ensure a significant increase in the retention rates of flavonoids and polysaccharides. Finally, through the addition of nano-silica, hydrogen bonds are formed between the surface hydroxyl groups and humic acid molecules to prevent their aggregation, thereby effectively reducing the probability of decay and phase separation of the modifier during storage and use, and greatly improving the component dispersibility and stability.

[0017] As a preferred embodiment, the composite functional material is a starch grafted acrylic acid-bentonite composite.

[0018] As a preferred embodiment, the preparation method of the starch grafted acrylic acid-bentonite composite specifically includes the following steps: S1: Stir corn starch and deionized water to form a transparent paste to obtain gelatinized starch; S2: After the gelatinized starch cools down, add acrylic acid and sodium-based bentonite, and slowly drop ammonium persulfate solution during the stirring process, heat up and keep warm for reaction for 2-3 h, and then add 0.1 wt% hydroquinone solution to terminate the reaction and stir evenly; S3: After the stirring is completed, wash with ethanol 2-3 times to remove unreacted monomers, hot air dry until the moisture content ≤2%, and the dried material is pulverized by a pulverizer and sieved and sealed to obtain.

[0019] As a preferred embodiment, the preparation method of the starch grafted acrylic acid-bentonite composite specifically includes the following steps: S1: Stir corn starch and deionized water at 85-90 °C for 30-40 min to form a transparent paste, obtaining gelatinized starch; S2: Cool the gelatinized starch to 70-75 °C, add acrylic acid and sodium-based bentonite, with a stirring speed of 200-300 rpm, slowly dropwise add ammonium persulfate solution, maintain the reaction at 70-75 °C for 2-3 h, and then add 0.1 wt% hydroquinone solution to terminate the reaction, and stir for 10-15 min; S3: After stirring is completed, wash with ethanol 2-3 times to remove unreacted monomers, dry at 70-75 °C with hot air until the moisture content ≤ 2%, crush the dried material with a pulverizer, and pass through a 200-250 mesh sieve, and seal to obtain.

[0020] As a preferred embodiment, the mass ratio of the corn starch, acrylic acid and sodium-based bentonite is (16-20):(4-6):(8-14).

[0021] As a preferred embodiment, the mass ratio of the corn starch and deionized water is 1:(4-5).

[0022] On the other hand, in this application, the addition of the starch grafted acrylic acid-bentonite composite effectively improves the slow release effect of the improved composition, and has a good water retention effect during use, stabilizes the soil structure, enhances soil stability, and endows the improved composition with good comprehensive performance. The composite synergistically acts through the hydrophilic group (-COOH) of the grafted acrylic acid and the layered structure of bentonite to form a three-dimensional network structure, adsorb and lock water, and further combines by enhancing the cation exchange capacity of bentonite and the adhesiveness of the grafted polymer to promote soil aggregate formation. The finally formed porous structure can load fertilizers or trace elements used together and slowly release them into the soil, and still maintain a stable structure in the soil. The modified high water absorption effect maintains soil humidity and greatly enhances its disintegration resistance in a high humidity environment.

[0023] As a preferred embodiment, the water retaining agent is a composition of potassium humate and sodium alginate.

[0024] As a preferred embodiment, the mass ratio of the potassium humate and sodium alginate is (7-9):(2-3).

[0025] As a preferred embodiment, the mass ratio of the potassium humate and sodium alginate is (8-8.5):(2.2-2.5).

[0026] As a preferred embodiment, the nutrient corrosion inhibitor is at least one of sulfur-coated urea, humic acid chelated zinc, calcium lignosulfonate and potassium dihydrogen phosphate.

[0027] As a preferred embodiment, the nutrient corrosion inhibitor is a composition of zinc humate and calcium lignosulfonate.

[0028] As a preferred embodiment, the mass ratio of zinc humate to calcium lignosulfonate is (5 - 6):(0.8 - 1.5).

[0029] As a preferred embodiment, the mass ratio of zinc humate to calcium lignosulfonate is (5 - 5.5):(0.8 - 1.2).

[0030] As a preferred embodiment, the passivator is at least one of nano-hydroxyapatite, attapulgite, montmorillonite, and sodium sulfide-modified biochar.

[0031] As a preferred embodiment, the passivator is nano-hydroxyapatite.

[0032] As a preferred embodiment, the microbial activator is at least one of yeast extract powder, EM bacteria, and amino acid powder.

[0033] As a preferred embodiment, the microbial activator is EM bacteria.

[0034] As a preferred embodiment, the solid powder is at least one of perlite powder, vermiculite powder, rice husk charcoal powder, sulfur powder, dolomite powder, and gypsum powder.

[0035] As a preferred embodiment, the solid powder is rice husk charcoal powder or perlite powder.

[0036] As a preferred embodiment, the regulator is at least one of potassium bicarbonate, ferrous sulfate, plant ash, and citric acid.

[0037] As a preferred embodiment, the regulator is potassium bicarbonate or ferrous sulfate.

[0038] The preparation method of the Potamogeton-based soil improvement composition specifically includes the following steps: S1: Add the Potamogeton treatment composition, the composite functional material, and all other raw materials into a double-screw mixer in sequence, with a rotation speed of 60 - 80 rpm, and mix for 30 - 40 min; S2: Add the product of S1 into a disk granulator, spray deionized water with a dosage of 3 - 5 wt% of the total material, control the particle size of granulation to be 2 - 4 mm, and after granulation, dry in a hot air drying oven at 60 - 70 °C until the moisture content ≤ 2%; S3: After drying, sieve the particles through a vibrating screen with a sieve aperture of 2 - 4 mm, and then package to obtain the product.

[0039] The beneficial effects of this application are:

[0040] 1. A Potamogeton crispus-based soil improvement composition provided in the present application significantly improves the application effect of Potamogeton crispus in the soil improvement composition on the basis of simplifying the existing treatment steps. Moreover, it can effectively improve the actual improvement effect of the Potamogeton crispus-based soil improvement composition and avoid the phenomena of corruption and phase separation during storage through formula combination, thereby realizing the recycling of aquatic plant waste, meeting the existing environmental protection requirements, and also providing good comprehensive application functions.

[0041] 2. A Potamogeton crispus-based soil improvement composition provided in the present application can significantly improve the various properties of the improvement composition by adding the treatment of the Potamogeton crispus treatment composition. After the Potamogeton crispus treatment composition is enzymatically hydrolyzed to break the cell wall and release cellulose and hemicellulose, the content of humic acid is greatly increased after fermentation, which can directly improve soil fertility, and can form stable complexes with heavy metals through its rich carboxyl and phenolic hydroxyl groups to reduce harmful effects. On the other hand, in the present application, the "enzymatic hydrolysis + compound microbial agent + directional fermentation" process significantly improves the humic acid generation efficiency in the composition, and the lower activation temperature can ensure a significant increase in the retention rates of flavonoids and polysaccharides. Finally, the addition of nano-silica forms hydrogen bonds with humic acid molecules through surface hydroxyl groups to prevent their aggregation.

[0042] 3. A Potamogeton crispus-based soil improvement composition provided in the present application effectively improves the slow-release effect of the improvement composition by adding starch-grafted acrylic acid-bentonite composites, and has a good water retention effect during use, stabilizes the soil structure, enhances soil stability, and endows the improvement composition with good comprehensive properties. The composite synergistically acts through the hydrophilic groups (-COOH) of grafted acrylic acid and the layered structure of bentonite to form a three-dimensional network structure, adsorb and lock water, and further combines with the cation exchange capacity of bentonite and the adhesiveness of the grafted polymer to promote soil aggregate formation. The finally formed porous structure can load fertilizers or trace elements used together and slowly release them into the soil, and maintain soil humidity through the modified high water absorption effect, and significantly enhance its disintegration resistance in a high humidity environment. Detailed implementation manners

[0043] In the detailed implementation manners, specific implementation cases will be used to more intuitively display and illustrate the content in the invention content of the present application.

[0044] Example 1

[0045] The Potamogeton crispus-based soil improvement composition, calculated by mass, consists of the following components: 51.5 parts of Potamogeton crispus treatment composition, 24.2 parts of composite functional material, 4.5 parts of water retaining agent, 6.2 parts of nutrient slow-release agent, 4.1 parts of passivator, 3.4 parts of microbial activator, 8.8 parts of solid powder, and 2.8 parts of regulator.

[0046] Preparation method of Potamogeton crispus treatment composition, by mass, specifically includes the following steps: S1: Wash 100 parts of Potamogeton crispus with a high-pressure water gun, cut it into sections of 4.5 cm, and crush it to a particle size of 1.2 mm. Then mix the crushed Potamogeton crispus with 0.5 part of cellulase (enzyme activity ≥ 5000 U / g), add 200 parts of deionized water, and keep it at 50 °C for 3 h; S2: After completion, mix 100 parts of the product of S1 with 5 parts of compound bacterial agent (Bacillus subtilis: Actinomycetes: Trichoderma viride = 2:1:1, total bacterial amount is 1.6×10 8 CFU / g), adjust the pH to 6.8, ferment at 45 °C for 7 days, and turn and push it every day; S3: Add a mixture of 3.5 parts of brown sugar and fish meal (brown sugar: fish meal = 3:1), maintain the humidity at 60%, and stand and ferment at 50 °C for 5 days; S4: Dry it with hot air at 80 °C until the moisture content is 1.8%, crush it to 250 mesh and mix it with 0.5 part of nano-silica, activate it at 60 °C for 3 h, and it is obtained after completion.

[0047] The composite functional material is a starch grafted acrylic acid-bentonite composite. By mass, its preparation method specifically includes the following steps: S1: Stir 20 parts of corn starch and 100 parts of deionized water at 85 °C for 40 min to form a transparent paste to obtain gelatinized starch; S2: Cool the gelatinized starch to 70 °C, add 5 parts of acrylic acid and 10 parts of sodium-based bentonite, stir at a speed of 240 rpm, slowly drop the ammonium persulfate solution, keep reacting at 70 °C for 2 h, and then add 0.2 part of 0.1 wt% hydroquinone solution to terminate the reaction, and stir for 12 min; S3: After stirring is completed, wash it with ethanol 3 times to remove unreacted monomers, dry it with hot air at 70 °C until the moisture content is 0.8%, crush the dried material with a pulverizer, pass through a 250-mesh sieve, and seal it to obtain.

[0048] The water retaining agent is a composition of potassium humate and sodium alginate, and the mass ratio is 8.1:2.4.

[0049] The nutrient corrosion inhibitor is a composition of humic acid chelated zinc and calcium lignosulfonate, and the mass ratio is 5.5:1. The humic acid chelated zinc is purchased from the agricultural grade product sold by Quanjia You Modern Agriculture Co., Ltd., Shandong, China.

[0050] The passivator is nano-hydroxyapatite, purchased from the 100-nm grade product sold by Beijing Decodaojin Co., Ltd., China.

[0051] The microbial activator is EM bacteria, purchased from the high-quality product sold by Jinan Guofeng Chemical Co., Ltd., China.

[0052] The solid powder is rice husk carbon powder, purchased from the soil standard grade product sold by Guangyuan Chemical Co., Ltd., Shandong, China; the regulator is potassium bicarbonate.

[0053] Preparation method of potamogeton crispus-based soil improvement composition, specifically including the following steps: S1: Add the potamogeton crispus treatment composition, composite functional material and all other raw materials into a double-screw mixer in sequence, with a rotation speed of 60 rpm and mix for 40 min; S2: Add the product of S1 into a disk granulator, spray deionized water, with the dosage being 4.5 wt% of the total material, control the particle size of granulation to be 2.5 mm, and after granulation, dry in a hot air dryer at 70 °C until the moisture content is 1.1%; S3: After drying, the particles are screened by vibration, the screening aperture is 2.5 mm, and they are obtained after packaging.

[0054] Example 2

[0055] This example only differs from Example 1 in the following aspects: For the potamogeton crispus-based soil improvement composition, calculated by mass, the raw materials are composed of the following components: 45 parts of potamogeton crispus treatment composition, 26 parts of composite functional material, 4.4 parts of water retaining agent, 5.5 parts of nutrient slow-release agent, 3.8 parts of passivator, 3.2 parts of microbial activator, 5.5 parts of solid powder, and 2.6 parts of regulator.

[0056] Example 3

[0057] This example only differs from Example 1 in the following aspects: For the potamogeton crispus-based soil improvement composition, calculated by mass, the raw materials are composed of the following components: 55 parts of potamogeton crispus treatment composition, 22 parts of composite functional material, 4.3 parts of water retaining agent, 6.2 parts of nutrient slow-release agent, 4.6 parts of passivator, 3.1 parts of microbial activator, 9.6 parts of solid powder, and 2.5 parts of regulator.

[0058] Comparative Example 1

[0059] This comparative example only differs from Example 1 in the following aspects: For the potamogeton crispus-based soil improvement composition, calculated by mass, the raw materials are composed of the following components: 75 parts of potamogeton crispus treatment composition, 10.5 parts of composite functional material, 4.5 parts of water retaining agent, 6.2 parts of nutrient slow-release agent, 4.1 parts of passivator, 3.4 parts of microbial activator, 8.8 parts of solid powder, and 2.8 parts of regulator.

[0060] Comparative Example 2

[0061] This comparative example only differs from Example 1 in the following aspects: The preparation method of the potamogeton crispus treatment composition, calculated by mass, specifically includes the following steps: S1: Wash 100 parts of potamogeton crispus with a high-pressure water gun, cut it into sections of 4.5 cm, crush it to a particle size of 1.2 mm, and then mix the crushed potamogeton crispus with 0.5 part of cellulase (enzyme activity ≥ 5000 U / g), add 200 parts of deionized water and keep it warm at 50 °C for 3 h; S2: After completion, mix 100 parts of the product of S1 with 2 parts of composite microbial agents (Bacillus subtilis: Actinomycetes: Trichoderma viride = 2:1:1, total bacterial amount is 1.6×10 8Mix with (CFU / g), adjust the pH to 6.8, ferment at 45 °C for 7 days, and turn and push every day; S3: Add a mixture of 3.5 parts of brown sugar and fish meal (brown sugar: fish meal = 1:3), maintain the humidity at 60%, and let it stand and ferment at 50 °C for 5 days; S4: Dry with hot air at 80 °C until the moisture content is 1.8%, crush to 250 mesh and mix with 0.5 part of nano-silica, and activate at 60 °C for 3 h. After completion, it is obtained.

[0062] Comparative Example 3

[0063] This comparative example is only different from Example 1 in the following aspects: The preparation method of the Potamogeton crispus treatment composition, in parts by mass, specifically includes the following steps: S1: Wash 100 parts of Potamogeton crispus with a high-pressure water gun, cut it into sections of 4.5 cm, crush it to a particle size of 1.2 mm, and then mix the crushed Potamogeton crispus with 0.5 part of cellulase (enzyme activity ≥ 5000 U / g), add 200 parts of deionized water, and keep it warm at 50 °C for 3 h; S2: After completion, mix 100 parts of the S1 product with 5 parts of a compound microbial agent (Bacillus subtilis: Trichoderma viride = 4:1, total bacterial count is 1×10 8 CFU / g), adjust the pH to 6.8, ferment at 45 °C for 7 days, and turn and push every day; S3: Add a mixture of 3.5 parts of brown sugar and fish meal (brown sugar: fish meal = 3:1), maintain the humidity at 60%, and let it stand and ferment at 50 °C for 5 days; S4: Dry with hot air at 80 °C until the moisture content is 1.8%, crush to 250 mesh and mix with 0.5 part of nano-silica, and activate at 60 °C for 3 h. After completion, it is obtained.

[0064] Comparative Example 4

[0065] This comparative example is only different from Example 1 in the following aspects: The composite functional material is a starch-grafted acrylic acid-bentonite composite. In parts by mass, its preparation method specifically includes the following steps: S1: Stir 20 parts of corn starch and 100 parts of deionized water at 85 °C for 40 min to form a transparent paste to obtain gelatinized starch; S2: Cool the gelatinized starch to 70 °C, add 10 parts of acrylic acid and 2 parts of sodium-based bentonite, stir at a speed of 240 rpm, slowly drop the ammonium persulfate solution, keep the reaction at 70 °C for 2 h, and then add 0.2 part of 0.1 wt% hydroquinone solution to terminate the reaction, and stir for 12 min; S3: After stirring is completed, wash with ethanol 3 times to remove unreacted monomers, dry with hot air at 70 °C until the moisture content is 0.8%, crush the dried material with a pulverizer, pass through a 250-mesh sieve, and seal to obtain.

[0066] Comparative Example 5

[0067] This comparative example is only different from Example 1 in the following aspects: The composite functional material is a starch-grafted acrylic acid-bentonite composite. In parts by mass, its preparation method specifically includes the following steps: S1: Stir 12 parts of corn starch and 60 parts of deionized water at 85°C for 40 min to form a transparent paste, obtaining gelatinized starch; S2: Cool the gelatinized starch to 70°C, add 0.5 part of acrylic acid and 18.5 parts of sodium-based bentonite, with a stirring speed of 240 rpm, slowly dropwise add ammonium persulfate solution, maintain the reaction at 70°C for 2 h, then add 0.2 part of 0.1 wt% hydroquinone solution to terminate the reaction, and stir for 12 min; S3: After the stirring is completed, wash with ethanol 3 times to remove unreacted monomers, dry at 70°C with hot air until the moisture content is 0.8%, crush the dried material with a pulverizer, pass through a 250-mesh sieve, and seal to obtain the product.

[0068] Comparative Example 6

[0069] This comparative example is only different from Example 1 in the following aspects: The preparation method of the Potamogeton crispus treatment composition. In parts by mass, it specifically includes the following steps: S1: Wash 100 parts of Potamogeton crispus with a high-pressure water gun, cut it into sections of 4.5 cm, crush it to a particle size of 1.2 mm, then mix the crushed Potamogeton crispus with 0.5 part of cellulase (enzyme activity ≥ 5000 U / g), add 200 parts of deionized water, and keep it at 50°C for 3 h; S2: After completion, mix 100 parts of the product of S1 with 5 parts of a composite microbial agent (Bacillus subtilis: Actinomycetes: Trichoderma viride = 2:1:1, total bacterial count is 1.6×10 8 CFU / g), adjust the pH to 6.8, ferment at 45°C for 7 days, and turn and push it every day; S3: Add a mixture of 3.5 parts of brown sugar and fish meal (brown sugar: fish meal = 3:1), maintain the humidity at 60%, and statically ferment at 50°C for 5 days; S4: Dry with hot air at 80°C until the moisture content is 1.8%, crush it to 250 meshes, and obtain the product after completion.

[0070] Performance Evaluation

[0071] 1. Conduct a water-holding capacity test on the improved compositions prepared in the examples and comparative examples. Referring to the standard NY / T1121.22 - 2010, mix the modifier with soil at a mass ratio of 1:5, dry it to a constant weight, soak it for 24 hours, centrifuge to remove free water, and calculate the water-holding rate % = (wet weight - dry weight) / dry weight × 100%. The results of 10 tests are averaged and recorded in Table 1.

[0072] 2. Conduct a soil structure improvement test on the improved compositions prepared in the examples and comparative examples. Mix the modifier with soil at a mass ratio of 1:10, and measure the pore ratio occupied by air in the soil through a pressure membrane apparatus. The results of 10 tests are averaged and recorded in Table 1.

[0073] 3. The improved compositions prepared in the examples and comparative examples were subjected to soil heavy metal improvement tests. For soil with an initial Cd concentration of 2.2 mg / kg, 5 wt% of the modifier was added, and after standing for 60 days, the content of available heavy metals was measured by ICP-MS. The average value of the content reduction rate obtained from 10 tests was calculated and recorded in Table 1.

[0074] Table 1 Performance evaluation results

[0075]

[0076] From the final performance test results of the examples and comparative examples, Comparative Examples 1-6 achieved worse performance results compared to the examples. The examples obtained more excellent Potamogeton crispus treatment compositions and composite functional materials because they adopted the better technical solutions defined in the present application. Through the combined action of the two, they maintained a good water retention effect, stabilized the soil structure, enhanced soil stability, and endowed the improved compositions with good comprehensive performance.

Claims

1. A soil improvement composition based on Potamogeton crispus, characterized in that: The raw materials are composed of the following components by weight: 40-60 parts of the water chestnut treatment composition, 20-30 parts of the composite functional material, 4-6 parts of the water retaining agent, 5-8 parts of the nutrient slow-release agent, 3-5 parts of the passivating agent, 3-4 parts of the microbial activator, 2-10 parts of the solid powder, and 2-3 parts of the regulator; The preparation method of the water chestnut treatment composition comprises: S1: mixing water chestnut and cellulase, adding deionized water, and keeping warm; S2: mixing the product of S1 with a composite bacterial agent, adjusting the pH, fermenting for 7-8 days, and turning over every day; S3: adding a mixture of brown sugar and fish meal, maintaining humidity, and standing and fermenting for 5-6 days; S4: hot air drying, crushing, mixing with nano-silicon dioxide, heating and activating, and obtaining the product after completion; The composite bacterial agent is a combination of Bacillus subtilis, actinomycetes and Trichoderma, with a mass ratio of (2-3): (1-1.5): (1-1.5), and the total bacterial amount of the composite bacterial agent is (1-2)×10 8 CFU / g.

2. The soil improvement composition based on Potamogeton crispus according to claim 1, characterized in that: The added amount of the nano silicon dioxide is 0.4-0.5wt%.

3. The soil improvement composition based on Potamogeton crispus according to claim 2, characterized in that: The composite functional material is a starch-grafted acrylic acid-bentonite composite, and the preparation method comprises: S1: stirring corn starch and deionized water to form a transparent paste to obtain gelatinized starch; S2: adding acrylic acid and sodium bentonite after cooling the gelatinized starch, dripping ammonium persulfate solution, heating and keeping the temperature to react, adding hydroquinone solution to terminate the reaction, and stirring; S3: washing after stirring to remove unreacted monomers, crushing after drying, sieving and sealing to obtain the composite functional material.

4. The soil improvement composition based on Potamogeton crispus according to claim 3, characterized in that: The mass ratio of the corn starch, acrylic acid and sodium bentonite is (16-20): (4-6): (8-14).

5. The soil improving composition based on Potamogeton crispus according to claim 4, characterized in that: The mass ratio of the corn starch to deionized water is 1:(4-5).

6. The soil improvement composition based on Potamogeton crispus according to claim 5, characterized in that: In the composition for treating water chestnuts, the mass ratio of the composite functional material and the solid powder particles is (45-55): (22-26): (5-10).

7. The soil improving composition based on Potamogeton crispus according to claim 6, characterized in that: The water retaining agent is a composition of potassium humate and sodium alginate, with a mass ratio of (7-9): (2-3).

8. The water chestnut-based soil improvement composition according to claim 7, characterized in that: The nutrient corrosion inhibitor is at least one of sulfur-coated urea, humic acid chelated zinc, calcium lignin sulfonate and potassium dihydrogen phosphate.

9. The soil improving composition based on Potamogeton crispus according to claim 8, characterized in that: The passivating agent is at least one of nano-hydroxyapatite, attapulgite, montmorillonite and sodium sulfide modified biochar.

10. A method for preparing the water chestnut-based soil improvement composition according to any one of claims 1 to 9, characterized in that: The specific steps include: S1: Add the water chestnut treatment composition, composite functional material and all other raw materials into a double-screw mixer in sequence, with a rotation speed of 60-80rpm and mix for 30-40min; S2: Add the product of S1 into a disc granulator and spray deionized water in an amount of 3-5wt% of the total material. The particle size of the granules is controlled to be 2-4mm. After granulation, dry in a hot air drying oven at 60-70℃ to a moisture content of ≤2%; S3: After drying, the particles are vibrated and sieved with a sieve aperture of 2-4mm, and then packaged.

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