A sea asparagus planting method and a modified composite-based planting soil

Abstract

The application discloses a sea flower planting method and a modified composite planting soil, and belongs to the technical field of aquatic plant planting and water ecological restoration. The method adopts a functional planting soil which is composed of humus soil, perlite, zeolite powder and calcium carbonate in a certain proportion, and the planting soil is pretreated by low-temperature plasma, then the planting soil is wrapped around the rhizome of sea flower seedlings, and is coated with degradable non-woven fabric, and after being made into an independent planting unit, is thrown into a target water body. By constructing a rhizosphere "ecological island" with an active repair function, the low-temperature plasma pretreatment constructs an "active library" in the matrix, can continuously release active substances, actively oxidizes and degrades rhizosphere organic pollutants, and converts part of nitrogen elements into a form that can be directly absorbed by plants, so that the active improvement of the rhizosphere microenvironment is realized.

Description

Technical Field

[0001] This invention belongs to the field of aquatic plant cultivation and aquatic ecological restoration technology, specifically involving a method for cultivating *Ottelia acuminata* based on modified composite planting soil combined with low-temperature plasma pretreatment. Background Technology

[0002] Water hyacinth is a rare and endangered submerged plant endemic to my country, mainly distributed in plateau lakes in Yunnan, Guangxi, and Guizhou provinces. It plays an important indicative role and ecological function in aquatic environments. Water hyacinth has high requirements for water quality, and its survival status is often used as an important reference for judging whether a water body is polluted.

[0003] Currently, the main methods for cultivating *Ottelia acuminata* fall into the following categories: First, seed storage and cultivation methods. For example, Chinese patent CN101702967A discloses a method for improving the germination rate of *Ottelia acuminata* seeds during winter storage and spring cultivation. The method involves keeping the seeds moist, burying them in a pot filled with loose, breathable mud and sand, and immersing the pot in water at a temperature not lower than 5°C for overwintering. The following spring, the *Ottelia acuminata* seeds are soaked in water at an ambient temperature of 20-25°C for about half a month. Linear leaves and roots will emerge successively. When the roots are about 3 cm long, the seedlings are transplanted into planting pots and placed in water. Later, they are transplanted into ponds with a depth of 1-1.5 meters. The above-mentioned existing technologies mainly focus on the seedling propagation stage of *Ottelia acuminata*, solving the problem of obtaining seedlings from seeds or tissue culture materials, but they cover less of the planting techniques in harsh aquatic environments.

[0004] In terms of technologies related to the cultivation of submerged plants and water body remediation, some improved solutions have been developed. For example, patent CN110946069A discloses a method for growing submerged plants in black and odorous sediment water. This method involves preparing a growth carrier for submerged plants using zeolite, shale ceramsite, and unpolluted sediment in a specific mass fraction. The growth carrier is then placed in a non-woven fabric bag, and the roots of the submerged plants are planted into the carrier before the bag is sealed. The plants are then introduced into the black and odorous sediment water at a specific planting density. In this invention, the zeolite and shale ceramsite that make up the growth carrier provide a favorable growth environment for the submerged plants and have a certain purifying effect on the water, thus improving the growth conditions for submerged plants and solving the problem of their difficulty in surviving in black and odorous sediment water.

[0005] The aforementioned existing technologies still have the following shortcomings: (1) Lacking the ability to actively regulate the rhizosphere microenvironment, existing technologies mostly adopt simple physical isolation or passive adsorption methods, relying on the physical adsorption of natural materials in the matrix (such as zeolite and ceramsite). Although it can improve the surrounding environment to a certain extent, the adsorption rate is limited and it cannot actively degrade organic pollutants accumulated around the rhizosphere.

[0006] (2) Difficult to cope with multiple environmental stresses. In eutrophic water bodies (such as Class IV water bodies), water hyacinth faces multiple stress factors such as the release of pollutants from bottom sediments, high concentration of suspended solids in the water, low transparency leading to insufficient light, and proliferation of pathogens. A single approach is not enough to comprehensively solve the above problems.

[0007] (3) For the reasons mentioned above, the survival rate of *Ottelia acuminata* in relatively harsh aquatic environments is generally low, making it difficult to support large-scale planting and ecological restoration projects. Summary of the Invention

[0008] The purpose of this invention is to provide a method for planting *Ottelia acuminata* and a modified composite planting soil. By constructing a rhizosphere "ecological island" with active repair function, the method significantly improves the success rate and growth vitality of *Ottelia acuminata* in relatively harsh water bodies (Class IV water bodies). The method is simple to operate and cost-controllable, providing an efficient and reliable technical solution for the large-scale planting of *Ottelia acuminata* and the ecological restoration of damaged water bodies.

[0009] The objective of this invention is achieved as follows: a method for cultivating *Ottelia acuminata*, comprising the following steps: (1) Mix the basic nutrient components, structural improvement components, functional adsorption components and mineral conditioning components in proportion to obtain composite planting soil; wherein, the basic nutrient components are humus, the structural improvement components are perlite, the functional adsorption components are zeolite powder, and the mineral conditioning components are calcium carbonate or dolomite powder. (2) The composite planting soil obtained in step (1) is subjected to low-temperature plasma pretreatment. The treatment conditions are: air is used as the working medium, and low-temperature plasma is generated under the condition of 10KV~20KV high voltage AC power. The treatment time is 5~10 minutes, so that the substrate surface is bombarded by high-energy particles to achieve harmless sterilization. At the same time, the density of hydrophilic functional groups on the substrate surface is increased, and the active particles generated by the plasma are loaded into the porous structure of the substrate to form an "active library" with slow-release function. (3) Wrap the plasma-modified composite planting soil obtained in step (2) around the root and stem part of the water hyacinth seedlings, and cover it with a non-woven fabric that is permeable to water and air and can be naturally degraded to make an independent planting unit. (4) The planting unit completed in step (3) is thrown into the target water body.

[0010] Further optimization, the mass percentage of each component in step (1) is: humus soil 30%~50%, perlite 20%~40%, zeolite powder 15%~30%, calcium carbonate 5%~15%.

[0011] Further optimization resulted in the following mass percentages for each component: 40% humus, 30% perlite, 20% zeolite powder, and 10% calcium carbonate.

[0012] Further optimization: in step (2), the low-temperature plasma uses air as the working medium and generates low-temperature plasma under 15KV high-voltage AC conditions. During the treatment, the composite planting soil is evenly spread in the insulating tray, the soil layer thickness is controlled at 1cm to 2cm, the soil moisture content is kept at about 15%, the plasma nozzle is about 2cm to 4cm away from the soil surface, and the treatment is carried out for 8 minutes in a room temperature and well-ventilated environment.

[0013] Further optimization involves using polylactic acid (PLA) nonwoven fabric or starch-based biodegradable nonwoven fabric in step (3) with a pore size of 50–200 mesh.

[0014] Further optimization involves using calcium carbonate as the mineral conditioning component in step (1).

[0015] Further optimization was made, and the target water body is now classified as Class IV lake water.

[0016] Further optimization involves making the composite planting soil into granules with a diameter of 3cm to 8cm in step (3) and then wrapping the roots and stems.

[0017] Further optimization is achieved by using a modified composite planting soil for planting water hyacinth, which is prepared by pretreatment of the following components by mass percentage: 30%–50% humus, 20%–40% perlite, 15%–30% zeolite powder, and 5%–15% calcium carbonate. The low-temperature plasma pretreatment uses air as the working medium and generates low-temperature plasma under 10KV–20KV high-voltage AC conditions for 5–10 minutes.

[0018] The outstanding and beneficial technical effects of this invention compared to existing technologies are: 1. It achieves a fundamental shift from "passive protection" to "active repair." This invention constructs an "active reservoir" within the matrix through low-temperature plasma pretreatment, which can sustainably release active substances, actively oxidize and degrade rhizosphere organic pollutants, and simultaneously convert some nitrogen elements into a form that plants can directly absorb, thus achieving active improvement of the rhizosphere microenvironment.

[0019] 2. Significantly improves the planting success rate under harsh water conditions. Using the method of this invention, the planting success rate of *Ottelia acuminata* in Class IV water bodies can reach over 80%, which is superior to existing methods.

[0020] 3. While planting water hyacinth, the zeolite powder and plasma active substances in the composite planting soil work synergistically to significantly reduce the ammonia nitrogen content and turbidity in the water, realizing a virtuous cycle of "purifying water with planting and promoting planting with water", and has the dual functions of planting and water purification.

[0021] 4. Simple operation, controllable cost, and environmentally friendly. After the planting units are completed, they can be directly placed by throwing, which is suitable for large-scale construction; all raw materials used are natural or environmentally friendly, and the biodegradable non-woven fabric does not produce secondary pollution; the low-temperature plasma treatment is a physical process without the addition of chemical reagents, making it environmentally friendly. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments. A method for planting *Ottelia acuminata* includes the following steps: (1) Preparation of composite planting soil: The basic nutrient components, structural improvement components, functional adsorption components and mineral conditioning components are mixed evenly in proportion to prepare composite planting soil. Among them, the basic nutrient component is humus, the structural improvement component is perlite, the functional adsorption component is zeolite powder, and the mineral conditioning component is calcium carbonate. The preferred mass percentage of each component is: humus 30% to 50%, perlite 20% to 40%, zeolite powder 15% to 30%, and calcium carbonate 5% to 15%. The humus provides the organic matter and mineral nutrients necessary for plant growth, providing a nutrient basis for the continuous growth of *Ottelia acuminata*. The perlite is used to construct a loose and porous rhizosphere structure, ensuring the oxygen supply required for root respiration, preventing the substrate from hardening in the underwater environment, and creating favorable conditions for the normal physiological activities of *Ottelia acuminata* roots. The zeolite powder possesses highly efficient ion exchange and adsorption capabilities, effectively capturing and fixing ammonia nitrogen and heavy metal ions in water and sediment leachate. Simultaneously, it adsorbs suspended particulate matter, algal debris, and other impurities in the water, reducing turbidity and improving water transparency. The calcium carbonate is used to maintain the pH stability of the rhizosphere microenvironment and supplement the calcium element required for the growth of *Ottelia acuminata*.

[0023] (2) Low-temperature plasma pretreatment: The composite planting soil obtained in step (1) is subjected to low-temperature plasma pretreatment. The treatment conditions are: using air as the working medium, low-temperature plasma is generated under 10KV~20KV high voltage AC power, and the treatment time is 5~10 minutes. Through the bombardment of high-energy particles of plasma, the substrate is sterilized and harmlessly treated. At the same time, the physical and chemical properties of the substrate surface are changed, the density of its surface hydrophilic functional groups is increased, and the active particles generated by plasma are loaded into the porous structure of the substrate to form an "active reservoir" with slow-release function. During the treatment, the composite planting soil is evenly spread in an insulating tray, the soil layer thickness is controlled at 1cm~2cm, the soil moisture content is maintained at about 15%, the plasma nozzle is about 2cm~4cm away from the soil surface, and the treatment is carried out at room temperature and in a well-ventilated environment for 5~10 minutes. During the low-temperature plasma treatment, a large amount of active oxygen, active nitrogen and other substances can be generated, thereby achieving soil surface sterilization, promoting nutrient activation and improving soil physical and chemical properties, providing a good soil environment for subsequent plant growth.

[0024] (3) Root wrapping and fixation: The plasma-modified composite planting soil obtained in step (2) is wrapped around the rhizomes of the *Ottelia acuminata* seedlings. The wrapping material is a non-woven fabric with good water and air permeability and biodegradability. This non-woven fabric structure can effectively lock the composite planting soil under the impact of water flow, preventing its loss, while allowing the *Ottelia acuminata* roots to penetrate and grow. The non-woven fabric wrapping material is preferably a biodegradable polylactic acid (PLA) non-woven fabric or a starch-based biodegradable non-woven fabric with a pore size of 50-200 mesh, which can effectively lock the composite planting soil while allowing free exchange of roots and water.

[0025] (4) Deployment: The planting unit that has been wrapped in step (3) is deployed into the target water body by throwing. The planting unit sinks to the bottom of the water.

[0026] After the planting unit sinks to the bottom of the water, it forms an isolated, clean, and oxygen-rich "ecological island" around the roots of the *Ottelia acuminata*. This ecological island has the following functions: the functional adsorption components have highly efficient ion exchange and adsorption capabilities, effectively capturing and fixing ammonia nitrogen and heavy metal ions in the water and sediment leachate. Simultaneously, it adsorbs suspended particulate matter, algal debris, and other impurities in the water, reducing turbidity and improving water transparency, thus improving light conditions for *Ottelia acuminata* growth. Mineral conditioning components maintain the pH stability of the rhizosphere microenvironment and supplement the calcium element needed for *Ottelia acuminata* growth. The planting soil undergoes low-temperature plasma pretreatment. Through high-energy particle bombardment by plasma, not only is the substrate sterilized and rendered harmless, but more importantly, the physicochemical properties of the substrate surface are altered, increasing the density of its hydrophilic functional groups. During this process, the active particles generated by the plasma are loaded into the porous structure of the substrate, forming an "active reservoir" with slow-release function. When the rhizomes of *Ottelia acuminata* wrapped in this modified matrix sink into the water, these active substances are gradually released, oxidizing and degrading organic pollutants around the rhizosphere, inhibiting the reproduction of anaerobic pathogens, reducing the accumulation of organic debris in the water, further reducing water turbidity, increasing transparency, improving underwater light penetration, and converting some nitrogen into a form that plants can absorb, thus realizing the transformation from "passive protection" to "active repair" and providing sufficient light support for *Ottelia acuminata* photosynthesis.

[0027] Example 1

[0028] A composite planting soil was prepared by thoroughly mixing 40% humus, 30% perlite, 20% zeolite powder, and 10% calcium carbonate. This composite planting soil was then placed in a low-temperature plasma treatment device, using air as the working medium, and treated for 8 minutes under 15KV high-voltage AC current to obtain plasma-modified composite planting soil. The modified composite planting soil was then wrapped around the rhizomes of *Ottelia acuminata* seedlings, forming granules approximately 5cm in diameter. These granules were then covered with biodegradable PLA nonwoven fabric (approximately 100 mesh) to create individual planting units. These planting units were then thrown into Class IV water bodies with a depth of 1.5–2.5 meters.

[0029] Results: 30 days after the release, the water transparency increased from the initial 30cm to over 65cm, the ammonia nitrogen concentration decreased by 42%, the success rate of planting *Ottelia acuminata* reached 80%, the plants grew vigorously, the leaves were emerald green, and the root system was well developed, which was significantly better than the traditional planting method.

[0030] Example 2

[0031] A composite planting soil was prepared by thoroughly mixing 30% humus, 35% perlite, 25% zeolite powder, and 10% calcium carbonate. This composite planting soil was then placed in a low-temperature plasma treatment device, using air as the working medium, and treated for 10 minutes under 10 kV high-voltage AC current to obtain plasma-modified composite planting soil. The modified composite planting soil was then wrapped around the rhizomes of *Ottelia acuminata* seedlings and covered with biodegradable starch-based nonwoven fabric (approximately 80 mesh) to create individual planting units. These planting units were then launched into Class IV water bodies with a depth of 1.5–2.5 meters using a throwing method.

[0032] Results: 30 days after the introduction, the water transparency increased from the initial 30cm to 50cm, ammonia nitrogen decreased by 38%, and the establishment success rate reached 68%.

[0033] Example 3

[0034] Using the formula from Example 1 (40% humus, 30% perlite, 20% zeolite powder and 10% calcium carbonate), after undergoing the same plasma treatment conditions, the composite planting soil was made into granules with a diameter of about 5 cm, wrapped around the roots and stems of the water hyacinth, and then covered with biodegradable non-woven fabric before being placed in an area with a water depth of about 3 meters.

[0035] Results: 30 days after the release, the water transparency increased from the initial 30cm to 45cm, ammonia nitrogen decreased by 15%, and the establishment rate was 50%.

[0036] Example 3 shows that when the water depth increases (3 meters), the light conditions are further weakened, and the success rate of planting decreases compared to shallow water areas, but it is still better than the traditional method.

[0037] Example 4

[0038] In Example 1, calcium carbonate was replaced with an equal amount of dolomite powder, and the remaining components, proportions, and plasma treatment conditions were the same as in Example 1.

[0039] Results: 30 days after the release, the water transparency increased from the initial 30cm to over 60cm, ammonia nitrogen decreased by 35%, and the establishment rate reached 60%.

[0040] Example 4 shows that the mineral conditioning components can be adjusted to some extent, but calcium carbonate is better than dolomite powder in maintaining rhizosphere pH, so the establishment rate (60%) is lower than that in Example 1 (80%).

[0041] Example 5 (without low-temperature plasma treatment)

[0042] Take 40% humus, 30% perlite, 20% zeolite powder and 10% calcium carbonate, mix them thoroughly and evenly, without low-temperature plasma treatment, directly wrap the roots and stems of the water hyacinth, cover the outside with biodegradable non-woven fabric, and throw it into Class IV water bodies at a depth of 1.5 to 2.5 meters.

[0043] Results: 30 days after the release, the water transparency increased from the initial 30cm to 50cm, ammonia nitrogen decreased by 38%, and the establishment rate reached 70%.

[0044] Example 5 shows that, even with the same formula, although the planting soil without low-temperature plasma activation also possesses a certain adsorption and purification capacity due to components such as zeolite powder (70% establishment rate), low-temperature plasma pretreatment further increases the establishment success rate by 10%, water transparency by more than 15 cm, and ammonia nitrogen removal rate by 4%. This indicates that the "active reservoir" constructed by plasma plays a significant synergistic role in the continuous degradation of pollutants and the improvement of underwater light.

[0045] Comparison of effects between Example 1 and Example 5 Example 1 (with plasma treatment) 30cm → 65cm and above 42% 80% Example 5 (Plasma-free treatment) 30cm → 50cm 38% 70% This demonstrates that low-temperature plasma pretreatment plays a crucial role in improving the final result.

[0046] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for cultivating *Ottelia acuminata*, characterized in that, Includes the following steps: (1) Mix the basic nutrient components, structural improvement components, functional adsorption components and mineral conditioning components in proportion to obtain composite planting soil; wherein, the basic nutrient components are humus, the structural improvement components are perlite, the functional adsorption components are zeolite powder, and the mineral conditioning components are calcium carbonate or dolomite powder. (2) The composite planting soil obtained in step (1) is subjected to low-temperature plasma pretreatment. The treatment conditions are: air is used as the working medium, and low-temperature plasma is generated under the condition of 10KV~20KV high voltage AC power. The treatment time is 5~10 minutes, so that the substrate surface is bombarded by high-energy particles to achieve harmless sterilization. At the same time, the density of hydrophilic functional groups on the substrate surface is increased, and the active particles generated by the plasma are loaded into the porous structure of the substrate to form an "active library" with slow-release function. (3) Wrap the plasma-modified composite planting soil obtained in step (2) around the rhizome of the water hyacinth seedlings, and cover it with biodegradable non-woven fabric to make an independent planting unit; (4) The planting unit completed in step (3) is thrown into the target water body.

2. The method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, The mass percentages of each component in step (1) are: humus 30%–50%, perlite 20%–40%, zeolite powder 15%–30%, and calcium carbonate 5%–15%.

3. The method for cultivating *Ottelia acuminata* according to claim 2, characterized in that, The mass percentages of each component are: humus 40%, perlite 30%, zeolite powder 20%, and calcium carbonate 10%.

4. The method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, In step (2), the low-temperature plasma uses air as the working medium and generates low-temperature plasma under 15KV high-voltage AC power. During the treatment, the composite planting soil is evenly spread in the insulating tray, the soil layer thickness is controlled at 1cm to 2cm, the soil moisture content is kept at about 15%, the plasma nozzle is about 2cm to 4cm away from the soil surface, and the treatment is carried out for 8 minutes in a room temperature and well-ventilated environment.

5. A method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, The biodegradable nonwoven fabric in step (3) is polylactic acid (PLA) nonwoven fabric or starch-based biodegradable nonwoven fabric with a pore size of 50-200 mesh.

6. The method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, The mineral conditioning component in step (1) is calcium carbonate.

7. A method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, The target water body is a Class IV lake.

8. The method for cultivating *Ottelia acuminata* according to claim 1, characterized in that, In step (3), the composite planting soil is made into granules with a diameter of 3cm to 8cm and then wrapped around the rhizomes.

9. A modified composite planting soil for planting *Ottelia acuminata* according to any one of claims 1-8, characterized in that, It is prepared by pretreatment of the following components by mass percentage: 30%–50% humus, 20%–40% perlite, 15%–30% zeolite powder, and 5%–15% calcium carbonate. The low-temperature plasma pretreatment uses air as the working medium and generates low-temperature plasma under 10KV–20KV high-voltage AC conditions for 5–10 minutes.