A method for constructing a system for remediating nitrogen and phosphorus pollution in drawdown zones through intercropping of paddy and dryland crops.

Abstract

This invention discloses a method for constructing a system to remediate nitrogen and phosphorus pollution in drawdown zones through intercropping, relating to the field of drawdown zone ecological restoration technology. The method includes the following steps: S1, dividing the drawdown zone from top to bottom into a dryland seedbed area, a first aquatic seedbed area, and a second aquatic seedbed area. Fast-growing leafy vegetables capable of absorbing and utilizing nitrogen and phosphorus nutrients are planted on the surface of all three areas using seedling trays; S2, crisscrossing ecological grass ditches are constructed in both the dryland and aquatic seedbed areas; S3, aquatic plants that reduce water wave disturbance to the drawdown zone soil surface are planted within the ecological grass ditches. This invention utilizes seedling trays for planting fast-growing leafy vegetables on the drawdown zone surface, minimizing human disturbance and significantly reducing soil erosion. It also enables the absorption and utilization of nitrogen and phosphorus nutrients, thereby reducing pollution in the drawdown zone and lowering the risk of eutrophication.

Description

Technical Field

[0001] This invention relates to the field of ecological restoration technology for drawdown zones, and more specifically to the technical field of a method for constructing a system for remediating nitrogen and phosphorus pollution in drawdown zone soils through intercropping of water and dryland crops. Background Technology

[0002] The drawdown zone is a special area formed by the periodic rise and fall of water levels in rivers, lakes, and reservoirs. As the last ecological barrier between the water and land systems, plants in the drawdown zone can intercept sediment and purify agricultural non-point source pollutants such as nitrogen and phosphorus. The root systems of these plants can also stabilize reservoir banks, prevent soil erosion, provide habitats for organisms, beautify the landscape, and maintain the dynamic balance of the water-land interface ecosystem. Due to the periodic flooding and exposure of the drawdown zone, its ecological environment undergoes significant changes. Native plants will die out and be replaced, the landscape will be fragmented, the ecosystem will be damaged, the pollutant interception and filtration function of the reservoir banks will be lost, and non-point source pollutants will accumulate, exacerbating pollution in the drawdown zone area and eutrophication of the reservoir water.

[0003] Currently, there are many ecological restoration technologies for drawdown zones. However, excessive engineering measures can damage the original landscape of the drawdown zone and reduce the growth space for green plants. Therefore, restoring vegetation in the drawdown zone to restore its ecological environment is a widely accepted approach. However, the plant species suitable for survival in drawdown zones are relatively limited. Due to varying site conditions, there is insufficient optimization of plant types, and planting methods lack standardized and efficient management. Various organisms do not form a well-structured and highly efficient integrated system, making widespread adoption difficult. Regarding the remediation of nitrogen and phosphorus pollution in drawdown zone soils, ecological treatments are rarely used; most methods combine physical and chemical techniques, resulting in high costs.

[0004] Currently, most methods used to restore nitrogen and phosphorus pollution in wetlands and lakes involve technologies such as ecological floating beds. These technologies are low-cost and environmentally friendly. However, ecological floating beds are not very suitable for drawdown zones with significant water level changes, especially during the dry season when they severely restrict plant growth. As a result, ecological floating beds are rarely used for the protection of drawdown zone slopes. It is difficult to absorb and utilize the nutrient-rich substances in the drawdown zone through the efficient absorption of nitrogen and phosphorus elements by aquatic plants. Furthermore, the effect of ecological floating beds on ecological slope protection and soil and water conservation in drawdown zones is not obvious. Summary of the Invention

[0005] The purpose of this invention is to address the technical problems of severe soil erosion, water loss, and poor nitrogen and phosphorus pollution remediation in existing drawdown zones. This invention provides a method for constructing a system for remediating nitrogen and phosphorus pollution in drawdown zones through intercropping of paddy and dryland crops. It employs a combination of various plant configurations and a simplified engineering composite ecological revetment structure to improve the system and overcome the aforementioned deficiencies.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] This invention provides a method for constructing a system to remediate nitrogen and phosphorus pollution in drawdown zones through intercropping, comprising the following steps:

[0008] S1. Divide the drawdown zone into sections. From top to bottom, the drawdown zone is divided into a dryland seedbed area, a first aquatic seedbed area, and a second aquatic seedbed area. On the surface of the dryland seedbed area, the first aquatic seedbed area, and the second aquatic seedbed area, fast-growing leafy vegetables that can absorb and utilize nitrogen and phosphorus nutrients are planted in seedling trays.

[0009] S2. The dryland seedbed area and the second aquatic seedbed area are sloping areas, while the first aquatic seedbed area is a horizontal area. Both the dryland seedbed area and the second aquatic seedbed area are equipped with crisscrossing ecological grass ditches. The ecological grass ditches divide the dryland seedbed area and the second aquatic seedbed area into several seedling tray placement areas. The fast-growing leafy vegetables in the dryland seedbed area and the second aquatic seedbed area are planted in the corresponding seedling tray placement areas.

[0010] S3. Plant aquatic plants in the ecological grass ditch to reduce the disturbance of water waves on the soil surface of the drawdown zone.

[0011] Specifically, fast-growing leafy vegetables are planted in seedling trays on the surface of the drawdown zone to minimize human disturbance to the surface of the drawdown zone and significantly reduce soil erosion.

[0012] In addition, the selected fast-growing leafy vegetables can absorb and utilize the eutrophic elements such as nitrogen and phosphorus in the drawdown zone system, thereby reducing pollution in the drawdown zone and lowering the risk of eutrophication of the water body.

[0013] In addition, the accompanying ecological grass ditch measures can prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus playing a role in soil stabilization and slope protection, reducing soil erosion and water loss. At the same time, it is beneficial to the growth and development of fast-growing leafy vegetables and the improvement of the vegetation landscape structure in the drawdown zone.

[0014] In one embodiment, in step S1, an overflow embankment, a drainage channel, and a series of embankments are sequentially arranged between the dryland seedbed area and the first aquatic seedbed area, and the overflow embankment, drainage channel, and series of embankments are all arranged horizontally.

[0015] Specifically, overflow embankments, drainage channels, and interconnected embankments are all horizontally designed to prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus stabilizing the soil and protecting the slopes, reducing soil erosion and water loss. This also benefits the growth and development of fast-growing leafy vegetables and improves the vegetation landscape structure of the drawdown zone.

[0016] In addition, the overflow embankments on the series of embankments regulate the water distribution between the two land use types; drainage channels are provided on the series of embankments to facilitate the rapid discharge of water during receding water, reduce the soaking of plants in the water, and reduce the damage to the bank slope caused by the sudden drop in water level in the drawdown zone.

[0017] In one embodiment, in step S1, an ecological slope, an overflow embankment, and a series of embankments are sequentially arranged between the first aquatic seedbed area and the second aquatic seedbed area. The ecological slope, the overflow embankment, and the series of embankments are all arranged horizontally.

[0018] Specifically, supporting measures such as ecological slope protection, overflow embankments, and interconnected embankments can prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus playing a role in soil stabilization and slope protection, reducing soil erosion and water loss. At the same time, it is beneficial to the growth and development of fast-growing leafy vegetables and the improvement of the vegetation landscape structure in the drawdown zone.

[0019] In one embodiment, the series of embankments are all sloping areas, and bermudagrass is planted on the series of embankments to block water flow and waves from eroding the ground surface.

[0020] Specifically, the series embankment is a series embankment made of bermudagrass. The root system of bermudagrass can coil around and consolidate the surface soil of the series embankment. The above-ground part of bermudagrass covers the series embankment, which can block the erosion of the surface by water flow and waves, increase the erosion resistance of the soil in the drawdown zone, and play an ecological slope protection role.

[0021] In one embodiment, in step S1, an energy-dissipating sedimentation tank is provided in the first aquatic seedbed area.

[0022] Specifically, energy dissipation sedimentation basins are mainly used for sediment deposition when the drawdown zone is flooded.

[0023] In one embodiment, in step S1, a protective cover with ventilation and water permeability holes is fitted onto the seedling tray, and the seedling tray is fixed to the drawdown zone by anchor rods. The seedling tray is provided with anchoring holes that allow the anchor rods to pass through.

[0024] Specifically, the seedling trays are equipped with protective covers and anchor bolts. These not only secure the trays for repeated use but also protect them from rising water levels and reduce soil erosion. The anchor bolts ensure stability during water level changes, and the protective covers minimize disturbance to the seedbed and corresponding drawdown zone soil during flooding. Multiple ventilation and drainage holes allow crops in the seedbed to breathe normally and support the growth of soil organisms in the drawdown zone.

[0025] In addition, the method of ecological floating beds can be combined when setting up seedling trays.

[0026] In one embodiment, several growing pots are evenly distributed on the seedling tray, and each growing pot is provided with a root penetration hole.

[0027] Specifically, the function of the growing pot is to hold the substrate that can support the survival of water spinach. The function of the root penetration hole is to facilitate the growth of water spinach roots into the drawdown zone soil through the gaps to absorb and utilize nutrients, thereby reducing nitrogen and phosphorus pollution.

[0028] In one implementation, in step S1, the fast-growing leafy vegetable is *Gnaphalium affine*.

[0029] Specifically, the target species for ecological restoration of the drawdown zone is the Chinese water spinach, which is easy to grow, can be used in both aquatic and terrestrial crops, and has a good absorption capacity for nutrients such as nitrogen and phosphorus. The Chinese water spinach has the advantages of high nutritional value, multiple harvests, and low planting conditions. When the Chinese water spinach plants are growing well, they should be harvested in time. The Chinese water spinach can not only efficiently absorb nitrogen and phosphorus elements, but also generate economic benefits through sales.

[0030] When planting, water spinach is planted on seedling trays. The seedling beds are arranged according to the characteristics of the dryland seedbed area, the first aquatic seedbed area, and the second aquatic seedbed area. The roots of water spinach absorb nitrogen and phosphorus elements from the drawdown zone.

[0031] In one implementation, when harvesting the first shoots of the Chinese cabbage, leave 2-3 nodes at the base and remove the tender shoots. When harvesting the lateral branches, leave 1-2 nodes at the base to encourage the growth of secondary lateral branches. Harvest every 7-10 days until the end of the harvest season.

[0032] Specifically, if the vines of *Ipomoea aquatica* are found to be growing too densely or are thin and weak during harvesting, some dense and weak branches can be thinned out to improve ventilation and light penetration. Later, some old roots can also be thinned to promote regeneration, ensuring strong new shoots and increasing economic benefits. This combination of *Ipomoea aquatica* and suitable herbaceous plants for the drawdown zone significantly reduces nitrogen and phosphorus pollutants in the drawdown zone, effectively improving its ecological environment, increasing vegetation cover, and reducing the risk of eutrophication.

[0033] In one implementation, in step S3, the aquatic plants in the ecological grass ditch are one or more of Bermuda grass, sweet flag, and bullwhip.

[0034] Specifically, the ecological swamp mainly planted with plants suitable for the drawdown zone, such as Bermuda grass, sweet flag, and bullwhip. Its function is to utilize the natural ecosystem of plants and soil to naturally filter, purify, store, and utilize water, intercept agricultural non-point source pollutants, improve the water resource utilization efficiency of the drawdown zone, purify water bodies, and the planted plants have well-developed root systems, which are conducive to soil consolidation, reducing soil erosion, minimizing water wave disturbance to the surface of the drawdown zone soil, and reducing the loosening of the topsoil layer.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. The method of this invention is simple to operate. It can repair nitrogen and phosphorus pollution in the drawdown zone and achieve the effect of ecological slope protection and bank protection by intercropping fast-growing leafy vegetables with dry land. The seedling tray planting mode adopted can reduce damage to the drawdown zone and also has certain economic benefits while efficiently reducing pollution and discharging pollutants.

[0037] 2. Combined with ecological grass gullies, ecological slope protection, overflow embankments, and interconnected embankments and other restoration measures, soil erosion is reduced, reservoir bank stability is improved, and the vegetation ecosystem of the drawdown zone is restored, thereby enabling the stable and sustainable development of the drawdown zone ecosystem.

[0038] 3. This invention can effectively intercept and purify nutrients such as nitrogen and phosphorus in the drawdown zone, and can significantly reduce the disturbance to the soil during the ecological restoration process of the drawdown zone while effectively restoring vegetation in the drawdown zone. It has certain economic value while preventing soil erosion and reducing eutrophication of reservoirs.

[0039] 4. Fast-growing leafy vegetables that can be grown in both paddy and dryland areas can absorb and utilize nutrients such as nitrogen and phosphorus in the drawdown zone, reducing the entry of non-point source pollutants into the reservoir and lowering the eutrophication level of the water body. Furthermore, water spinach has a high survival rate, strong self-renewal ability, and requires no special management throughout its growth process. It requires little investment, consumes little energy, is easy to manage, has good ecological effects, and can be harvested multiple times a year, thus having certain economic benefits.

[0040] 5. A variety of plant species are combined to not only maintain biodiversity and restore and preserve the naturalness of the plant landscape, but also to intercept and retain sediment, reduce reservoir siltation and pollution, and improve soil erosion in the reservoir drawdown zone. The integration of various ecological engineering projects further reduces the scouring effect of water bodies, effectively preventing soil erosion and water loss.

[0041] 6. The use of seedling trays for planting, secured with anchor bolts, offers advantages such as simpler structure, easier and faster construction, and better stability and reliability of anchoring. Furthermore, seedling tray planting minimizes disturbance to the drawdown zone ground, eliminating the need for tilling. The selected seedling trays are made of environmentally friendly materials and will not pollute the drawdown zone ecosystem. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a method for constructing a system to remediate nitrogen and phosphorus pollution in drawdown zone soils through intercropping of water and dryland crops.

[0043] Figure 2 yes Figure 1 Top view.

[0044] Figure 3 This is an overhead view of the dryland seedbed area or the first aquatic seedbed area.

[0045] Figure 4 It is a cross-sectional view of the dryland seedbed area or the first aquatic seedbed area.

[0046] Figure 5 This is a schematic diagram of the protective cover.

[0047] Attached labels: 1-Dryland seedbed area, 2-Ecological grass ditch, 3-First aquatic seedbed area, 4-Ecological slope protection, 5-Overflow embankment, 6-Series embankment, 7-Drainage channel, 8-Energy dissipation sedimentation pond, 9-Anchor hole, 10-Growing pot, 11-Root penetration hole, 12-Anchor rod, 13-Protective cover, 14-Ventilation and water permeability hole. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0052] Example 1

[0053] like Figures 1 to 2 As shown in the figure, this embodiment provides a method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zone soils through intercropping, including the following steps:

[0054] S1. Divide the drawdown zone into sections. From top to bottom, the drawdown zone is divided into dryland seedbed area 1, first aquatic seedbed area 3, and second aquatic seedbed area. On the surface of dryland seedbed area 1, first aquatic seedbed area 3, and second aquatic seedbed area, fast-growing leafy vegetables that can absorb and utilize nitrogen and phosphorus nutrients are planted in seedling trays.

[0055] S2. Dryland seedbed area 1 and the second aquatic seedbed area are sloping areas, while the first aquatic seedbed area 3 is a horizontal area. Both dryland seedbed area 1 and the second aquatic seedbed area are equipped with crisscrossing ecological grass ditches 2. The ecological grass ditches 2 divide the dryland seedbed area 1 and the second aquatic seedbed area into several seedling tray placement areas. The fast-growing leafy vegetables in the dryland seedbed area 1 and the second aquatic seedbed area are planted in the corresponding seedling tray placement areas.

[0056] S3. Plant aquatic plants in the ecological grass ditch 2 to reduce the disturbance of water waves on the soil surface of the drawdown zone.

[0057] Specifically, fast-growing leafy vegetables are planted in seedling trays on the surface of the drawdown zone to minimize human disturbance to the surface of the drawdown zone and significantly reduce soil erosion.

[0058] In addition, the selected fast-growing leafy vegetables can absorb and utilize the eutrophic elements such as nitrogen and phosphorus in the drawdown zone system, thereby reducing pollution in the drawdown zone and lowering the risk of eutrophication of the water body.

[0059] In addition, the accompanying ecological grass ditch measures can prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus playing a role in soil stabilization and slope protection, reducing soil erosion and water loss. At the same time, it is beneficial to the growth and development of fast-growing leafy vegetables and the improvement of the vegetation landscape structure in the drawdown zone.

[0060] Example 2

[0061] This embodiment is a further optimization based on Embodiment 1, specifically:

[0062] In step S1, an overflow embankment 5, a drainage channel 7, and a series of embankments 6 are sequentially arranged between the dryland seedbed area 1 and the first aquatic seedbed area 3. The overflow embankment 5, the drainage channel 7, and the series of embankments 6 are all arranged horizontally.

[0063] Specifically, measures such as overflow embankments 5, drainage channels 7, and interconnected embankments 6 are all horizontally arranged, which can prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus playing a role in soil stabilization and slope protection, reducing soil erosion and water loss. At the same time, it is conducive to the growth and development of fast-growing leafy vegetables and the improvement of the vegetation landscape structure in the drawdown zone.

[0064] In addition, the overflow embankment 5 on the series embankment 6 regulates the water distribution between the two land use types; drainage channels 7 are provided on the series embankment 6 to facilitate the rapid discharge of water during receding water, reduce the soaking of plants in water, and reduce the damage to the bank slope caused by the sudden drop in water level in the drawdown zone.

[0065] Example 3

[0066] This embodiment is a further optimization based on embodiment 1 or 2, specifically:

[0067] In step S1, an ecological slope protection 4, an overflow embankment 5, and a series of embankments 6 are sequentially arranged between the first aquatic seedbed area 3 and the second aquatic seedbed area. The ecological slope protection 4, the overflow embankment 5, and the series of embankments 6 are all arranged horizontally.

[0068] Specifically, the supporting measures such as ecological slope protection 4, overflow embankments 5, and interconnected embankments 6 can prevent surface runoff and waves from directly eroding the soil in the drawdown zone, thus playing a role in soil stabilization and slope protection, reducing soil erosion and water loss. At the same time, it is beneficial to the growth and development of fast-growing leafy vegetables and the improvement of the vegetation landscape structure in the drawdown zone.

[0069] Example 4

[0070] This embodiment is a further optimization based on any one of embodiments 1 to 3, specifically:

[0071] All six embankments are sloping areas, and bermudagrass is planted on them to prevent water flow and waves from eroding the ground.

[0072] Specifically, the series embankment 6 is a bermudagrass series embankment 6. The root system of bermudagrass can coil around and consolidate the surface soil of the series embankment 6. The above-ground part of bermudagrass covers the series embankment 6, which can block the erosion of the ground surface by water flow and waves, increase the erosion resistance of the soil in the drawdown zone, and play the role of ecological slope protection 4.

[0073] Example 5

[0074] This embodiment is a further optimization based on any one of embodiments 1 to 4, specifically:

[0075] In step S1, an energy-dissipating sedimentation tank 8 is provided in the first aquatic seedbed area 3.

[0076] Specifically, the energy dissipation sedimentation pond 8 is mainly used for sediment deposition when the drawdown zone is flooded.

[0077] Example 6

[0078] like Figures 3 to 5 As shown, this embodiment is a further optimization based on any one of embodiments 1 to 5, specifically:

[0079] In step S1, a protective cover 13 with ventilation and water permeability holes 14 is fitted onto the seedling tray. The seedling tray is fixed to the drawdown zone by anchor rods 12. Anchoring holes 9 are provided on the seedling tray to allow the anchor rods 12 to pass through.

[0080] Specifically, the seedling trays are equipped with protective covers 13 and anchor rods 12. These not only secure the trays for repeated use but also protect them from rising water levels and reduce soil erosion. The anchor rods 12 ensure stability during water level changes, allowing for multiple uses. The protective covers 13 minimize disturbance to the seedbed and corresponding drawdown zone soil during flooding. Multiple ventilation and drainage holes 14 facilitate normal respiration of crops in the seedbed and promote the growth of soil organisms in the drawdown zone.

[0081] In addition, the method of ecological floating beds can be combined when setting up seedling trays.

[0082] Several growing pots 10 are evenly distributed on the seedling tray, and each growing pot 10 is provided with a root penetration hole 11.

[0083] Specifically, the function of the growing pot 10 is to hold the substrate that can support the survival of water spinach. The function of the root penetration hole 11 is to facilitate the growth of water spinach roots into the drawdown zone soil through the gap to absorb and utilize nutrients, thereby reducing nitrogen and phosphorus pollution.

[0084] Example 7

[0085] This embodiment is a further optimization based on any one of embodiments 1 to 6, specifically:

[0086] In step S1, the fast-growing leafy vegetable is water spinach.

[0087] Specifically, the target species for ecological restoration of the drawdown zone is the Chinese water spinach, which is easy to grow, can be used in both aquatic and terrestrial crops, and has a good absorption capacity for nutrients such as nitrogen and phosphorus. The Chinese water spinach has the advantages of high nutritional value, multiple harvests, and low planting conditions. When the Chinese water spinach plants are growing well, they should be harvested in time. The Chinese water spinach can not only efficiently absorb nitrogen and phosphorus elements, but also generate economic benefits through sales.

[0088] When planting, water spinach is planted on seedling trays. The seedling beds are arranged according to the characteristics of dryland seedbed area 1, first aquatic seedbed area 3 and second aquatic seedbed area. The roots of water spinach absorb nitrogen and phosphorus elements from the drawdown zone.

[0089] When harvesting water spinach for the first time, leave 2-3 nodes at the base and pick off the tender shoots. When harvesting lateral branches, leave 1-2 nodes at the base to encourage the growth of secondary lateral branches. Harvest every 7-10 days until the end of the harvest season.

[0090] Specifically, if the vines of *Ipomoea aquatica* are found to be growing too densely or are thin and weak during harvesting, some dense and weak branches can be thinned out to improve ventilation and light penetration. Later, some old roots can also be thinned to promote regeneration, ensuring strong new shoots and increasing economic benefits. This combination of *Ipomoea aquatica* and suitable herbaceous plants for the drawdown zone significantly reduces nitrogen and phosphorus pollutants in the drawdown zone, effectively improving its ecological environment, increasing vegetation cover, and reducing the risk of eutrophication.

[0091] Example 8

[0092] This embodiment is a further optimization based on any one of embodiments 1 to 7, specifically:

[0093] In step S3, the aquatic plants in the ecological grass ditch 2 are one or more of Bermuda grass, sweet flag, and bullflower.

[0094] Specifically, the ecological grass ditch 2 mainly planted Bermuda grass, sweet flag, and bullwhip, which are suitable plants for the drawdown zone. Its function is to use the natural ecosystem of plants and soil to naturally filter, purify, store and utilize water, intercept agricultural non-point source pollutants, improve the water resource utilization efficiency of the drawdown zone, purify water bodies, and the planted plants have well-developed root systems, which are conducive to soil consolidation, reduce soil loss, minimize water wave disturbance to the surface of the drawdown zone soil, and reduce the loosening of the topsoil layer.

Claims

1. A method for constructing a system for remediating nitrogen and phosphorus pollution in drawdown zones through intercropping, characterized in that, Includes the following steps: S1. The drawdown zone is divided into three sections from top to bottom: dryland seedbed area (1), first aquatic seedbed area (3), and second aquatic seedbed area. Fast-growing leafy vegetables that can absorb and utilize nitrogen and phosphorus nutrients are planted on the surface of the dryland seedbed area (1), first aquatic seedbed area (3), and second aquatic seedbed area through seedling trays. Between the dryland seedbed area (1) and the first aquatic seedbed area (3), there are overflow embankments (5), drainage channels (7), and connecting embankments (6) in sequence. Between the first aquatic seedbed area (3) and the second aquatic seedbed area, there are ecological slope protection (4), overflow embankments (5), and connecting embankments (6) in sequence. The connecting embankments (6) are all sloping areas. Bermuda grass is planted on the connecting embankments (6) to block water flow and waves from eroding the surface. The seedling tray is fitted with a protective cover (13) with ventilation and water permeability holes (14). The seedling tray is fixed to the drawdown zone by anchor rods (12). The seedling tray is provided with anchoring holes (9) that allow the anchor rods (12) to pass through. Several growing pots (10) are evenly distributed on the seedling tray. Each growing pot (10) is provided with root penetration holes (11). S2. The dryland seedbed area (1) and the second aquatic seedbed area are sloping areas, and the first aquatic seedbed area (3) is a horizontal area. The dryland seedbed area (1) and the second aquatic seedbed area are both equipped with crisscrossing ecological grass ditches (2). The ecological grass ditches (2) divide the dryland seedbed area (1) and the second aquatic seedbed area into several seedling tray placement areas. The fast-growing leafy vegetables in the dryland seedbed area (1) and the second aquatic seedbed are planted in the corresponding seedling tray placement areas. S3. Plant aquatic plants in the ecological grass ditch (2) to reduce the disturbance of water waves on the soil surface of the drawdown zone.

2. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zones using intercropping as described in claim 1, characterized in that, In step S1, the overflow embankment (5), drainage channel (7) and series embankment (6) are all set horizontally.

3. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zones using intercropping as described in claim 1, characterized in that, In step S1, the ecological slope protection (4), the overflow embankment (5), and the series embankment (6) are all set horizontally.

4. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zones using intercropping as described in claim 1, characterized in that, In step S1, an energy dissipation sedimentation tank (8) is provided in the first aquatic seedbed area (3).

5. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zones using intercropping as described in claim 1, characterized in that, In step S1, the fast-growing leafy vegetable is water spinach.

6. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zone soils according to claim 5, characterized in that, When harvesting water spinach for the first time, leave 2-3 nodes at the base and pick off the tender shoots. When harvesting lateral branches, leave 1-2 nodes at the base to encourage the growth of secondary lateral branches. Harvest every 7-10 days until the end of the harvest season.

7. The method for constructing a soil nitrogen and phosphorus pollution remediation method for drawdown zones using intercropping as described in claim 1, characterized in that, In step S3, the aquatic plants in the ecological grass ditch (2) are one or more of Bermuda grass, sweet flag, and bullwhip.

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