A salt-draining planting structure for improving saline-alkali soil

Abstract

The application relates to a salt-draining planting structure for improving saline-alkali soil, which comprises, from top to bottom, a planting layer, a filter layer, a dehydration layer, an isolation layer and a saline-alkali layer. The filter layer comprises a sandstone layer at the lower part and an AM fungus layer at the upper part. The sandstone layer is formed by wrapping sandstone with geotextile. The dehydration layer comprises a first-stage drainage layer, a second-stage drainage layer, a third-stage drainage layer and a fourth-stage drainage layer. The bottom of the first-stage drainage layer, the second-stage drainage layer and the third-stage drainage layer is respectively provided with a first-stage water guide pipe layer, a second-stage water guide pipe layer and a third-stage water guide pipe layer. The four-stage drainage system, the three-stage water guide system and the relatively closed saline-alkali soil improvement space are utilized to realize the maximum recovery of the saline-alkali infiltration water. The long-term salt-draining function can not only realize the long-term improvement of the saline-alkali soil and the transformation of the productivity, but also is environment-friendly. Through the periodic long-term salt-draining, the saline-alkali soil can be gradually changed into good farmland.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive treatment of saline-alkali soil, and particularly relates to a salt-draining planting structure for improving saline-alkali soil. BACKGROUND

[0002] Saline-alkali soil is formed under certain natural conditions, and the essence of the formation is that soluble salt ions continuously accumulate on the surface of soil, thereby changing the physical and chemical properties of soil, leading to undesirable changes in basic characteristics of soil and decline in quality. At present, there are 3690 million hm 2 Saline soil accounts for 5.01% of the total available land area in China, and is mainly distributed in the northeast, north China, northwest, middle and lower reaches of the Yangtze River and coastal areas.

[0003] Saline-alkali soil is one of the most important low-yield soil types in China, and its causes are complex. The stubbornness and repeatability of saline-alkali soil are the main obstacle factors for treatment. The early research on saline soil treatment mainly focuses on water regulation, deep ploughing and other aspects, and a single measure for treating saline soil is proposed according to the characteristics of different saline soils. Subsequently, many researchers propose to use multiple comprehensive treatments such as applying soil conditioners, planting halophytes and using microbial fertilizers. The treatment of saline soil not only can alleviate the problem of shortage of available land resources in China, but also has an important role in the development of agricultural productivity and regional ecological quality in the areas where saline soil is distributed.

[0004] However, there are still some problems in the treatment of saline soil at present, such as serious pollution of soil and groundwater caused by large-scale application of soil conditioners, incomplete recovery of subsurface drainage water, risk of reverse salt, poor sustainability of saline-alkali improvement, easy repetition, and so on. SUMMARY

[0005] The purpose of the present application is to solve the above-mentioned problems in the treatment of saline-alkali soil, and a salt-draining planting structure for improving saline-alkali soil is proposed. By combining biological measures with engineering measures, a periodic planting system in the basic year and the planting year is proposed in the aspect of biological improvement, so as to achieve the purpose of long-term salt control.

[0006] In order to achieve the above object, the application provides a salt-removing planting structure for improving saline-alkali soil, which comprises a planting layer, a filter layer, a dehydration layer, an isolation layer and a saline-alkali layer arranged in sequence from top to bottom.

[0007] Preferably, the thickness of the planting layer is 0.4-1.0 m, the thickness of the filter layer is 15-20 cm, and the thickness of the dehydration layer is 0.8-1.0 m.

[0008] Preferably, the thickness of the AM fungus layer is 10-20 mm.

[0009] Preferably, the pebble particle size of the first-stage drainage layer is 4-8 mm, the pebble particle size of the second-stage drainage layer is 8-16 mm, the pebble particle size of the third-stage drainage layer is 16-24 mm, and the pebble particle size of the fourth-stage drainage layer is 24-32 mm.

[0010] Preferably, the vertical distance between the first-stage water guide pipe layer, the second-stage water guide pipe layer and the third-stage water guide pipe layer is 10-15 cm.

[0011] Preferably, the radius of the pipe of the first-stage water guide pipe layer is 5-10 cm, and the spacing of the pipes in the layer is 15-60 m according to the different burial depths and soil qualities; the radius of the pipe of the second-stage water guide pipe layer is 8-12 cm, and the pipes are arranged below the pipes of the first-stage water guide pipe layer and adjacent to the pipes of the first-stage water guide pipe layer; the pipes in the third-stage water guide pipe layer are cylindrical pipes with a diameter of 12-18 cm, and the spacing of the pipes in the layer is 20-80 m.

[0012] Preferably, the ventilation pipe and the exhaust pipe are respectively provided with a ventilation valve and an exhaust port.

[0013] Preferably, the isolation layer is formed by laying a sodium-based bentonite in the upper layer and a geomembrane in the lower layer.

[0014] The application also provides a method for improving saline-alkali soil by using the salt-draining planting structure, which comprises the following steps: in the first year, planting leguminous green manure in the planting layer, and simultaneously, inoculating AM fungi, and returning the mature leguminous green manure and AM fungi to the field; in the second year, interplanting leguminous green manure and salt-tolerant plants; in the third year, planting and returning leguminous green manure to the field; in the fourth year, interplanting leguminous green manure and salt-tolerant plants; and the above steps are repeated every two years, and the first year is the base year, the second year is the planting year, and the normal plants are planted, and the four years are the first stage; after two cycles, the interplanting of leguminous green manure and salt-tolerant plants is restored, and the second stage is formed.

[0015] Based on the above technical solution, the application has the following advantages:

[0016] In the aspect of engineering measures, the four-stage drainage system, the three-stage water guide system and the relatively closed saline-alkali soil improvement space are used to realize the maximum recovery of the percolation water under the saline-alkali soil, and the recovery rate of the percolation water can be significantly improved, and the reverse salt can be avoided compared with the prior art. The salt-draining planting structure can not only realize long-term improvement of the saline-alkali soil and transformation of the productivity, but also is environmentally friendly.

[0017] The application uses biological measures to improve the soil quality of the planting layer, reduces the evaporation of the plough layer, improves the soil structure and improves the soil fertility; and uses engineering measures to drain water and remove salt, and blocks the capillary reverse salt. The biological measures and the engineering measures complement each other and play a role together, and the effect of one plus one is greater than two. Through periodic long-term salt removal, the saline-alkali soil can be completely treated, and the goal of gradually changing the saline-alkali soil into good farmland can be finally achieved. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the application, and form a part of the application. The schematic embodiments of the application and the descriptions thereof are used to explain the application, and do not constitute an improper limitation on the application. In the drawings:

[0019] Figure 1 The figure is a cross-sectional view of the salt-draining planting structure for improving the saline-alkali soil;

[0020] Figure 2 The figure is a structure schematic view of the four-stage drainage system of the dehydration layer;

[0021] Figure 3 The figure is a top view schematic view of the pipe network of the dehydration layer;

[0022] Figure 4 The figure is a top view structure schematic view of the third-stage water guide pipe. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] This invention provides an improved salt-draining planting structure for saline-alkali land, comprising, from top to bottom, a planting layer, a filter layer, a dehydration layer, an isolation layer, and a saline-alkali layer. Figures 1-4 As shown, a preferred embodiment of the present invention is illustrated.

[0025] like Figure 1 As shown, the salt-draining planting structure for improving saline-alkali land includes, from top to bottom, a planting layer 1, a filter layer 2, a dehydration layer 3, an isolation layer 4, and a saline-alkali layer 5. The filter layer 2 comprises a lower sand and gravel layer 22 and an upper AM fungus layer 21. The sand and gravel layer 21 is formed by wrapping sand and gravel with geotextile. Preferably, the thickness of the planting layer 1 is 0.4–1.0 m, the thickness of the filter layer 2 is 15–20 cm, and the thickness of the dehydration layer 3 is 0.8–1.0 m.

[0026] The filter layer 2 consists of two layers: an AM fungal layer 21 and a sand and gravel layer 22, which together form the filter layer 2 of the system. This facilitates biological improvement, enhances the filtration effect, and cuts off capillary channels. The AM fungal layer 21 is 10-20 mm thick. When the roots of the planted layer come into contact with it, it can increase the infection of the plant roots and enhance the biological improvement effect. Furthermore, because it is a solid fungal agent, including vermiculite, zeolite, etc., it has similar physical properties to sand and gravel, which reduces the amount of sand and gravel used to a certain extent.

[0027] The sand and gravel layer 22 is formed by wrapping sand and gravel with geotextile. The sand and gravel have been washed beforehand. The two layers of geotextile on the top and bottom of the sand and gravel layer serve a dual purpose: better filtering of soil, preventing clogging of the permeable pores, and the upper geotextile also provides some support for the bacterial agent. The sand and gravel layer 22 in filter layer 2 is wrapped with two layers of non-woven fabric, which can significantly reduce the risk of clogging of the permeable pores and increase the infiltration rate during long-term salt removal.

[0028] like Figure 2 As shown, the dehydration layer 3 comprises a first-level drainage layer 17, a second-level drainage layer 18, a third-level drainage layer 19, and a fourth-level drainage layer 20, formed by pebbles with gradually increasing particle size from top to bottom. Preferably, the pebble particle size of the first-level drainage layer 17 is 4-8 mm, the pebble particle size of the second-level drainage layer 18 is 8-16 mm, the pebble particle size of the third-level drainage layer 19 is 16-24 mm, and the pebble particle size of the fourth-level drainage layer 20 is 24-32 mm.

[0029] The first three drainage layers have different gravel particle sizes and different gap sizes, so that the water infiltration rate is different (the smaller the particle size, the smaller the infiltration rate), which is more conducive to the step-by-step filtration of water and salt, and finally collects and discharges, thereby increasing the water collection rate. The fourth drainage layer has the largest gravel particle size, and the pores between the gravels are relatively large, which is more conducive to the water absorption rope collecting all the residual saline-alkali water in the pores.

[0030] According to the different filling gravel particle sizes, different porosities, and different water infiltration rates, a four-stage drainage system is set up. The first-stage drainage layer has the smallest gravel particle size, and the water infiltrates relatively slowly, which can ensure that as much water as possible is collected and discharged by the first-stage water guide pipe, and can also filter out some impurities to reduce the blockage of the water guide pipe. The porosities of the following stages gradually increase, and the infiltration rate gradually increases, so that although the water gradually decreases, it can also ensure that the saline-alkali water is successfully infiltrated or absorbed into the water guide pipe, and finally discharged from the system, so that the recovery rate of saline-alkali water reaches the maximum.

[0031] As shown in Figure 3 , the four-stage drainage system is provided with a three-stage water guide system, the first and second stages of the water guide pipe layer along the direction of the field ridge, and the third stage of the water guide pipe layer perpendicular to the direction of the field ridge, forming a "three-dimensional composite field-shaped" pipe network.

[0032] The present application proposes a "three-dimensional composite field-shaped" dehydration pipe network, which uses a three-stage water guide system to significantly improve the collection rate of infiltrated water. In particular, the setting of the third stage of the water guide pipe plays a necessary recycling role for the part of the saline-alkali water that still infiltrates after being discharged by the first and second stages of the water guide pipe, and solves the problem of incomplete water recovery in the traditional saline-alkali soil system.

[0033] Specifically, the bottom of the first-stage drainage layer 17, the second-stage drainage layer 18, and the third-stage drainage layer 19 is respectively provided with the first-stage water guide pipe layer 6, the second-stage water guide pipe layer 8, and the third-stage water guide pipe layer 10. The first-stage water guide pipe layer 6 and the second-stage water guide pipe layer 8 are provided with a plurality of water guide pipes along the direction of the field ridge, and the third-stage water guide pipe layer 10 is provided with a plurality of water guide pipes perpendicular to the direction of the field ridge. The pipeline of the first-stage water guide pipe layer 6 and the second-stage water guide pipe layer 8 is a half-cylindrical shape with the plane upward. A plurality of water-permeable holes are distributed in an S shape on the pipeline of the first-stage water guide pipe layer 6 and the second-stage water guide pipe layer 8 to increase the water-permeable area. This design can not only improve the water collection rate, but also save the amount of water guide pipe to some extent.

[0034] Preferably, the vertical distance between the first, second and third water guide pipe layers 6, 8 and 10 is 10-15 cm. The first and second water guide pipe layers differ from the conventional cylindrical pipes in that they use semi-cylindrical water guide pipes. Preferably, the pipe radius of the first water guide pipe layer 6 is 5-10 cm, and the spacing between the pipes in the layer is 15-60 m, depending on the depth of burial and the soil quality; the pipe radius of the second water guide pipe layer 8 is 8-12 cm, and the pipes are arranged below the pipes of the first water guide pipe layer and spaced apart from the pipes of the first water guide pipe layer, i.e. the second water guide pipe layer 8 and the pipes of the first water guide pipe layer are arranged in a spaced-apart manner in the projection direction of the pipes on the top view, as shown in Figure 3

[0035] Compared with the conventional cylindrical water guide pipes, the semi-cylindrical water guide pipes of the first and second water guide systems have a larger water-permeable area directly contacted by the upper layer, which is more conducive to the collection and discharge of saline-alkali water, and can also save the raw materials for the drainage pipes.

[0036] The first and second water guide pipe layers 6 and 8 are connected to the first and second drainage pipes 7 and 9, respectively, to discharge the saline-alkali water, which is recycled after treatment. After dehydration by the first and second water guide pipe layers, some saline-alkali water still infiltrates and is not discharged by the drainage pipes. The conventional technology ignores this part of the infiltrating water, resulting in incomplete salt discharge and the risk of salt rebound. The third water guide pipe layer 10 is added on this basis, and the pipes in the third water guide pipe layer 10 are cylindrical pipes with a diameter of 12-18 cm and a spacing of 20-80 m.

[0037] Further, the lower half of the third water guide pipe layer 10 is connected to the upper ends of a plurality of water absorption ropes 15, the lower ends of the water absorption ropes 15 are located in the fourth drainage layer 20, and the two ends of the third water guide pipe layer 10 are respectively connected to the air inlet pipe 12 and the air outlet pipe 13 extending to the ground, and the third water guide pipe layer 10 is filled with a desulfurized gypsum layer 16. Preferably, the air inlet pipe 12 and the air outlet pipe 13 are respectively provided with an air inlet valve 11 and an air outlet 14.

[0038] One end of the third water guide pipe layer 10 is connected to the air inlet pipe 12, which extends upward to the ground, and the air inlet valve 11 controls the air inlet time and air inlet amount; the other end is connected to the air outlet pipe 13, which extends upward to the ground at both ends, and the air outlet 14 is subjected to air inlet and waterproof treatment. By continuously supplying flowing air to the dehydration pipe, the evaporation of water in the third water guide pipe is facilitated, and the capillary action is ensured to continue.

[0039] ​Meanwhile, a proper amount of desulfurization gypsum is added into the third level water guide pipe layer 10 to form a desulfurization gypsum layer 16 to treat the residual saline-alkali water absorbed by the water absorption rope, replace sodium ions with calcium ions, eliminate salinity, and avoid salt accumulation in the third level water guide pipe layer 10 and around the water absorption rope 15. Compared with directly treating saline-alkali water with a large amount of desulfurization gypsum, the method has less harm to the environment and can be almost ignored.

[0040] Further, the isolation layer 4 is formed by laying sodium-based bentonite on the upper layer and a geomembrane on the lower layer, which double guarantees the blocking of the capillary action of the soil and prevents the upward movement of groundwater. The sodium-based bentonite can form a high-density transverse diaphragm when it comes into contact with water, has extremely low water permeability, and has strong water retention performance. The sodium-based bentonite is a natural material and will not pollute the surrounding environment and is not prone to aging or corrosion, so it has long-lasting waterproof performance. The geomembrane is a kind of anti-seepage material formed by the compounding of a high-density plastic film and a non-woven fabric, and has good corrosion resistance, stability, hydraulic characteristics, and isolation and sealing characteristics.

[0041] The isolation layer separates the saline-alkali layer from the dehydration layer, the filtering layer, and the planting layer to form a relatively closed saline-alkali land improvement space, ensures that the saline-alkali layer is not disturbed during the improvement process, and realizes the goal of changing saline-alkali land into good farmland. The isolation layer not only prevents the upward movement of water and salt in the saline-alkali layer, but also has water absorption function in case that the saline-alkali water is not completely collected and discharged by the dehydration layer.

[0042] In the aspect of engineering measures, the four-level drainage system, the three-level water guide system, and the relatively closed saline-alkali land improvement space are used to realize the maximum recovery of the saline-alkali infiltration water, which can significantly improve the recovery rate of the infiltration water and avoid reverse salt compared with the previous technology. The salt-removing planting structure can realize long-term improvement of saline-alkali land and conversion of productivity. The salt-removing planting structure has little impact on the environment, which can be ignored, can maximize the improvement of saline-alkali land, and can meet the environmental protection requirements without polluting the soil and groundwater.

[0043] The salt-removing planting structure uses biological measures to improve the soil quality of the planting layer, reduces evaporation of the plough layer, improves the soil structure, and improves the soil fertility; and uses engineering measures to drain and remove salt and block capillary reverse salt. The biological measures and the engineering measures complement each other and jointly play a role to achieve the effect of one plus one greater than two. Through periodic long-term salt removal, the saline-alkali land is completely treated, and the goal of gradually changing the saline-alkali land into good farmland can be finally realized.

[0044] Based on the above salt-removing planting structure, the application also provides a method for improving saline-alkali soil by using the salt-removing planting structure, which comprises the following steps: in the first year, planting leguminous green manure, and at the same time, inoculating AM fungi to infect the leguminous green manure, and after maturing, returning the leguminous green manure to the field; in the second year, interplanting leguminous green manure and salt-tolerant plants; in the third year, planting leguminous green manure and returning the leguminous green manure to the field (the same as in the first year); in the fourth year, interplanting leguminous green manure and salt-tolerant plants (the same as in the second year); every two years is a cycle, the first year is the base year, the saline-alkali soil is improved, the second year is the planting year, plants are normally planted, and the above four years are referred to as the first stage. After two cycles, the interplanting of leguminous green manure and salt-tolerant plants is resumed, that is, the planting year, which is the second stage.

[0045] Planting green manure plants can avoid the exposure of the soil surface layer to the air, increase the water locking capacity of the soil surface layer, and at the same time, prevent the phenomenon of salt return of the soil surface layer caused by the upward penetration of surface water due to the insufficient water content of the soil surface layer. In the growth process of the green manure plants, water in the soil can be continuously absorbed, and the soil water level can be lowered, thereby reducing the probability of salt return. In the process of improving soil fertility, the metabolism of the green manure falls into the soil, can be converted into organic fertilizer, and increases the soil fertility. At the same time, the amount of biological nitrogen fixation can be increased, and K + , which is beneficial to the accumulation of soil organic phosphorus content and the increase of soil available potassium and slow-release potassium content, and improves the degree of saline-alkali soil.

[0046] Compared with single planting, this two-stage two-cycle planting method increases a biological improvement step in the base year, improves the fertility and improves the saline-alkali soil, thereby providing a basis guarantee for planting plants in the planting year, and continuously returning the plants to the field can improve the soil organic matter and porosity, and relieve the blockage problem of the dehydration layer water guide pipe.

[0047] The AM fungi inoculated in the planting layer are mixed strains of various AM fungi, which improve the biodiversity of saline-alkali soil. Under the stress of saline-alkali, AM fungi can improve the rhizosphere soil environment of plant growth, regulate the absorption of water and nutrients by plants, thereby effectively relieving the physiological drought under the stress of saline-alkali, promoting the growth and production of plants, and improving the salt-tolerance of plants. The mycelium network formed by the mycelium of AM fungi can expand the absorption area of roots, increase the water absorption capacity of plants, regulate the absorption of P, Zn and Cu by plants, and even the absorption of N, K, Mn, B and S elements, and relieve the physiological drought of plants.

[0048] The application proposes a periodic planting system of base years and planting years. Legume green manure is planted in each base year, and a small amount of AM fungi is inoculated in the legume green manure and is applied to the field. Not only is the biological improvement process increased by one year, but also the in-situ large-scale propagation of AM fungi is achieved with the least amount of application, which greatly reduces the use amount of AM fungi in the subsequent planting year biological improvement. The AM fungi layer on the filter layer surface plays a dual role, improves the physical and chemical properties of the soil, and improves the plant growth conditions. At the same time, the perennial application to the field can also play the role of loosening the soil, increasing the soil porosity, and improving the saline-alkali soil.

[0049] The biological improvement method of "green manure + AM fungi + organic fertilizer + periodic intercropping" is commonly used. Compared with the previous single biological improvement, a relatively suitable soil environment can be provided for plant planting in the base year, the degree of salinity and alkalinity can be significantly reduced in the planting year, the plant survival rate can be improved, and the plant can grow normally.

[0050] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application.

Claims

1. A salt-draining planting structure for improving saline-alkali land, characterized in that: The application relates to a salt-alkali soil improvement device, which comprises, from top to bottom, a planting layer (1), a filtering layer (2), a dehydration layer (3), an isolation layer (4) and a salt-alkali layer (5), wherein the filtering layer (2) comprises a sandstone layer (22) at the bottom and an AM fungus layer (21) at the top; the sandstone layer (22) is formed by wrapping sandstone with geotextile; the dehydration layer (3) comprises a first-stage drainage layer (17), a second-stage drainage layer (18), a third-stage drainage layer (19) and a fourth-stage drainage layer (20) which are formed by filling and laying pebbles with gradually increasing particle sizes from top to bottom; the bottom of the first-stage drainage layer (17), the second-stage drainage layer (18) and the third-stage drainage layer (19) is respectively provided with a first-stage water guide pipe layer (6), a second-stage water guide pipe layer (8) and a third-stage water guide pipe layer (10); a plurality of water guide pipes in the first-stage water guide pipe layer (6) and the second-stage water guide pipe layer (8) are arranged along the direction of the field ridge; a plurality of water guide pipes in the third-stage water guide pipe layer (10) are arranged perpendicular to the direction of the field ridge; the pipes in the first-stage water guide pipe layer (6) and the second-stage water guide pipe layer (8) are half-cylindrical pipes with the plane upward; a plurality of water-permeable holes are distributed in an S shape on the pipes in the first-stage water guide pipe layer (6) and the second-stage water guide pipe layer (8); the first-stage water guide pipe layer (6) and the second-stage water guide pipe layer (8) are respectively connected with a first-stage drainage pipe (7) and a second-stage drainage pipe (9); the lower half of the third-stage water guide pipe layer (10) is connected with the upper ends of a plurality of water absorption ropes (15); the lower ends of the water absorption ropes (15) are located in the fourth-stage drainage layer (20); the two ends of the third-stage water guide pipe layer (10) are respectively connected with an air inlet pipe (12) and an air outlet pipe (13) which extend to the ground; and the third-stage water guide pipe layer (10) is filled with a desulfurized gypsum layer (16); the thickness of the planting layer (1) is 0.4-1.0 m; the thickness of the filtering layer (2) is 15-20 cm; and the thickness of the dehydration layer (3) is 0.8-1.0 m; and the thickness of the AM fungus layer (21) is 10-20 mm.

2. The salt rejecting planting structure according to claim 1, wherein: The particle size of the pebbles in the first-stage drainage layer (17) is 4-8 mm; the particle size of the pebbles in the second-stage drainage layer (18) is 8-16 mm; the particle size of the pebbles in the third-stage drainage layer (19) is 16-24 mm; and the particle size of the pebbles in the fourth-stage drainage layer (20) is 24-32 mm.

3. The salt rejecting planting structure according to claim 1, wherein: The vertical distance between the first-stage water guide pipe layer (6), the second-stage water guide pipe layer (8) and the third-stage water guide pipe layer (10) is 10-15 cm.

4. The salt rejecting planting structure according to claim 3, wherein: The radius of the pipes in the first-stage water guide pipe layer (6) is 5-10 cm, and the interval of the pipes in the layer is 15-60 m; the radius of the pipes in the second-stage water guide pipe layer (8) is 8-12 cm, and the pipes are arranged below and adjacent to the pipes in the first-stage water guide pipe layer (6); the pipes in the third-stage water guide pipe layer (10) are cylindrical pipes with a diameter of 12-18 cm, and the interval of the pipes in the layer is 20-80 m.

5. The salt rejecting planting structure as claimed in claim 1, wherein: The ventilation pipe (12) and the exhaust pipe (13) are respectively provided with a ventilation valve (11) and an exhaust port (14).

6. The salt rejecting planting structure according to claim 1, wherein: The isolation layer (4) is formed by laying sodium bentonite on the upper layer and a geomembrane on the lower layer.

7. A method for improving saline-alkali soil using the salt-removing planting structure according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: planting leguminous green manure in the planting layer (1) in the first year, and simultaneously inoculating AM fungi, and returning the mature leguminous green manure to the soil, planting leguminous green manure and salt-tolerant plants in the second year, planting leguminous green manure and returning the leguminous green manure to the soil in the third year, and planting leguminous green manure and salt-tolerant plants in the fourth year, and every two years is a cycle, the first year is a base year, the second year is a planting year, normal plants are planted, and four years are a first stage; after two cycles, the leguminous green manure and the salt-tolerant plants are planted in a two-way mode, and a second stage is formed.

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