A root zone salt removal system based on vacuum negative pressure porous infiltration pipes and a method thereof

Abstract

The application discloses a root layer salt discharge system based on a vacuum negative pressure porous infiltration pipe and a method thereof. The irrigation and drainage system (1) comprises a shallow ditch (11), a water distribution pit (12), a water storage tank (13), a plurality of infiltration pipes (14), a pipeline (15) and a first electromagnetic valve (23), and the field control system (2) comprises an instrument storage pile (21), a central processing unit (22), a data transmission line (24) and a soil water and salt sensor (25). According to the needs of field irrigation and salt discharge automation, specific soil moisture and salt thresholds are set in combination with the field control system, so that dynamic and accurate regulation and control of farmland water and salt are realized. The application can effectively reduce the vertical deep seepage amount of water and solute, improve the desalination amount under the unit leaching water amount, realize the effects of water saving and salt control, and avoid the secondary pollution caused by leaching water.

Description

Technical Field

[0001] This invention relates to a root zone salt removal system and method based on a vacuum negative pressure porous infiltration pipe, belonging to the field of farmland irrigation and drainage technology. Background Technology

[0002] Subsurface drip irrigation is a micro-irrigation technology for farmland. It uses porous seepage pipes buried underground to bring irrigation water to a certain depth in the soil below the ground surface. By regulating the water supply pressure in the pipes, it can achieve low-intensity and continuous irrigation of the crop root zone.

[0003] Currently, subsurface irrigation is widely used in greenhouse cultivation due to its advantages of low material cost, good water-saving effect, and small land area. However, compared with open fields, greenhouses lack natural rainwater leaching, and the frequent application of chemical fertilizers and pesticides makes it easy for soil salt to accumulate in the root zone, which will harm crop growth in the long run.

[0004] Irrigation leaching is a common method of soil desalination, primarily involving injecting excessive amounts of fresh water into the target field. The water infiltrates and carries salts from the soil to deeper layers, achieving a salt-suppressing effect. However, irrigation leaching typically covers the entire field, while the localized micro-irrigation methods commonly used in greenhouse farms lead to localized solute accumulation, ultimately reducing the desalination benefits of the leaching water. Therefore, for soil salt leaching in greenhouses, it is necessary to increase the lateral discharge of leached water to limit the accumulation and diffusion of solutes in the vertical soil profile and prevent secondary soil pollution. Furthermore, it is crucial to focus on targeted desalination of specific soil areas to avoid ineffective leaching. Based on the working mechanism of infiltration pipes, during soil leaching, it is possible to try to adjust the infiltration pipes to a negative pressure state, thereby forming suction around the pipe wall to counteract the capillary force of the soil on water retention during the seepage process. This allows for the extraction of water from the saturated or near-saturated zone of the soil during the irrigation infiltration process, achieving simultaneous vertical infiltration and lateral drainage. This reduces the amount of water and solutes that seep into the deep vertical layer, improves the desalination efficiency per unit volume of leaching water, achieves the goal of water conservation and salt control, and reduces secondary pollution caused by leaching water. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a root layer salt drainage system and method based on vacuum negative pressure porous infiltration pipes. This system can effectively reduce the amount of water and solute seepage into the deep vertical layer, increase the desalination capacity per unit volume of leaching water, and achieve the effects of water conservation, salt control and avoidance of secondary pollution caused by leaching water. Specifically, the present invention provides a root layer salt drainage system and method based on vacuum negative pressure porous infiltration pipes, including an irrigation and drainage system and a field control system.

[0006] Preferably, the present invention provides a root layer salt drainage system based on vacuum negative pressure porous infiltration pipes, including an irrigation and drainage system and a field control system, wherein the field control system is installed on the irrigation and drainage system;

[0007] The irrigation and drainage system includes shallow ditches, water distribution pits, water storage tanks, several seepage pipes, pipelines, and a first solenoid valve. The target field has water distribution pits and several shallow ditches arranged at equal intervals. Seepage pipes are laid in the shallow ditches arranged at equal intervals. The water storage tank is connected to the seepage pipes and water distribution pits through pipelines. The first solenoid valve is installed on the pipelines.

[0008] Preferably, the irrigation and drainage system includes a second pipe, a second solenoid valve, an air pump, a sedimentation tank, and a waste liquid tank. The air pump is connected to the sedimentation tank, the sedimentation tank is connected to the seepage pipe through the second pipe, the second solenoid valve is installed on the second pipe, and the sedimentation tank is connected to the waste liquid tank.

[0009] Prior to this, the field control system includes an instrument storage pile, a central processing unit, a data transmission line, and a soil water and salt sensor. The central processing unit is installed on the instrument storage pile and is connected to the soil water and salt sensor via the data transmission line.

[0010] Preferably, the field control system includes a water flow sensor, which is installed on the pipeline and connected to a central processing unit.

[0011] Preferably, the first solenoid valve and the second solenoid valve are connected to the central processing unit.

[0012] Preferably, the precipitator includes a precipitator frame, a triangular base, a turbidity sensor, a hinge, and a detachable surface. The triangular base is fixedly installed at the bottom inside the precipitator frame, the turbidity sensor is fixedly installed at the top inside the precipitator frame, and the detachable surface is installed on the precipitator frame via the hinge.

[0013] The bottom of the shallow ditch has a slope of 2° to 6° from the beginning to the end of the field, and the bottom of the ditch at the beginning of the field is higher than the bottom of the ditch at the end of the field.

[0014] Preferably, a root zone desalination method based on vacuum negative pressure porous infiltration pipes, based on any one of the root zone desalination systems based on vacuum negative pressure porous infiltration pipes, performs the following steps:

[0015] If the crops in the target field are still growing, an emergency rinsing strategy is implemented using the central processor;

[0016] If no crops are growing in the target field, a maintenance rinsing strategy is adopted using the central processor;

[0017] Emergency rinsing strategies include:

[0018] The central processing unit controls the opening of the first solenoid valve, and the water in the water storage tank is injected into the water distribution pit. The water in the water distribution pit flows into the shallow ditch at the end of the field.

[0019] If the soil water and salt sensor buried at the end of the field detects that the soil moisture data of the seepage pipe reaches the preset target soil saturation water content, the central processing unit will control the first solenoid valve to close.

[0020] When the soil moisture content fed back by the soil water and salt sensor at the same burial depth as the seepage pipe reaches the field water holding capacity of the preset target field for the first time, the central processing unit controls the air pump to start, and the negative pressure intensity in the sedimentation tank connected to the air pump gradually increases, thereby generating the same intensity of negative pressure inside the seepage pipe.

[0021] When the capillary water suction of the soil around the seepage pipe is lower than the negative pressure strength inside the seepage pipe, water around the seepage pipe enters the seepage pipe and the seepage pipe is used to extract the leached water from the soil.

[0022] The leachate extracted from the seepage pipe enters the sedimentation tank. The turbidity sensor monitors the data of particulate silt-like floating matter in the leachate in the sedimentation tank. The central processing unit controls the second solenoid valve to open, and discharges the water in the sedimentation tank into the waste liquid tank.

[0023] When the soil moisture content reported by the soil water and salt sensor is lower than the field water holding capacity of the preset target field, the central processing unit controls the air pump to shut down.

[0024] Preferred maintenance rinsing strategies include:

[0025] Calculate the total amount of water used for rinsing:

[0026]

[0027] In the formula: Q is the amount of water required for maintenance leaching; n is the number of shallow ditches; h1 is the distance between the bottom depth of the shallow ditch at the beginning of the field and the burial depth of the infiltration pipe; w1 is the width of the bottom of the shallow ditch at the beginning of the field; h2 is the distance between the bottom depth of the shallow ditch at the end of the field and the burial depth of the infiltration pipe; w2 is the width of the bottom of the shallow ditch at the end of the field; L is the length of the target field; θ s It is the volumetric saturation water content of the soil in the target field;

[0028] The central processing unit controls the opening of the first solenoid valve, and the water flow sensor accurately records the amount of water flowing through the first solenoid valve and feeds it back to the central processing unit.

[0029] When the water flow sensor detects that the water flow through the first solenoid valve has reached the set water flow threshold, the central processing unit controls the first solenoid valve to close.

[0030] The water flowing out of the storage tank is injected into the water distribution pit and then flows into each shallow ditch;

[0031] When the soil moisture content fed back by the soil water and salt sensor reaches the field water holding capacity of the preset target field for the first time, the central processing unit controls the air pump to start, and the negative pressure intensity in the sedimentation tank gradually increases, thereby generating the same intensity of negative pressure inside the seepage pipe.

[0032] When the capillary water suction of the soil around the seepage pipe is lower than the negative pressure strength inside the seepage pipe, water around the seepage pipe enters the seepage pipe and the seepage pipe is used to extract the leached water from the soil.

[0033] The leachate extracted from the seepage pipe enters the sedimentation tank through the inlet;

[0034] Using a turbidity sensor to monitor particulate silt-like floating matter in the leachate in a sedimentation tank;

[0035] Based on the data of particulate silt-like floating matter fed back by the turbidity sensor, the central processing unit controls the second solenoid valve to open and discharge the leachate in the sedimentation tank into the waste liquid tank.

[0036] When the soil moisture content reported by the soil water and salt sensor is lower than the field water holding capacity of the preset target field, the central processing unit controls the air pump to shut down.

[0037] Prior to planting, soil moisture data is collected in real time using soil water and salt sensors and fed back to the central processing unit.

[0038] If the central processing unit receives soil moisture data from the soil water and salt sensor that reaches the preset crop drought tolerance limit, it controls the first solenoid valve to open, allowing water from the storage tank to flow into each infiltration pipe. The first solenoid valve is then closed when the soil moisture data fed back by the soil water and salt sensor reaches 70% to 75% of the field capacity of the preset target field.

[0039] The beneficial effects achieved by this invention are as follows:

[0040] (1) This invention can effectively reduce the amount of water and solute seeping into the deep vertical layer, increase the desalination rate per unit volume of leaching water, and achieve the effects of water conservation, salt control, and avoidance of secondary pollution caused by leaching water. Specifically, it provides a root layer salt removal system and method based on vacuum negative pressure porous infiltration pipes, including an irrigation and drainage system and a field control system. Under the premise of meeting the desalination requirements, this invention reduces the dependence on freshwater resources and improves the desalination efficiency of farmland by utilizing the irrigation and drainage system and the field control system.

[0041] (2) There is no need to re-lay out pipelines for desalination. Only seepage pipes need to be installed below the field. This invention does not reduce the original planting area.

[0042] (3) The present invention provides real-time monitoring and regulation of soil water and salt, and high dynamic accuracy of soil water and salt management.

[0043] (4) The system of the present invention is fully automatic, saving manpower.

[0044] (5) This invention integrates the function of wastewater collection, avoiding secondary pollution caused by the extracted leachate. Attached Figure Description

[0045] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the overall system structure;

[0047] Figure 2 This is a schematic diagram of the field structure;

[0048] Figure 3 A top-down view of the field;

[0049] Figure 4 This is a schematic diagram of the cross-section AA of the field.

[0050] Figure 5 This is a schematic diagram of the longitudinal section BB of the field.

[0051] Figure 6 This is a schematic diagram of the precipitator structure;

[0052] Figure 7 This is a flowchart of the system operation process.

[0053] In the diagram: 11: Shallow ditch; 12: Water distribution pit; 13: Water storage tank; 14: Infiltration pipe; 15: Pipeline; 16: Air pump; 17: Sedimenter; 171: Inlet; 172: Outlet; 173: Vent; 174: Triangular base; 175: Turbidity sensor; 176: Hinge; 177: Detachable panel; 18: Waste liquid tank; 21: Instrument storage peg; 22: Central processing unit; 23: First solenoid valve; 24: Data transmission line; 25: Soil water and salt sensor; 26: Water flow sensor. Detailed Implementation

[0054] To facilitate the explanation of the technical solution of this application, some concepts involved in this application will be explained first below.

[0055] It should be noted that if there are directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention, they are only used to explain the relative positional relationship and movement of the components in a certain specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0056] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0057] See Figure 1 This application provides a schematic diagram of a root zone salt drainage system based on a vacuum negative pressure porous infiltration pipe. The system includes an irrigation and drainage system 1 and a field control system 2. According to the root zone salt drainage system and method based on a vacuum negative pressure porous infiltration pipe provided by this invention, the irrigation and drainage system 1 includes a shallow ditch 11, a water distribution pit 12, a water storage tank 13, an infiltration pipe 14, a rigid plastic pipe 15, a vacuum pump 16, a sedimentation tank 17, and a waste liquid tank 18.

[0058] refer to Figures 2-5 The shallow ditch 11 is a channel for the flow of irrigation water from the beginning to the end of the field. The cross-section of the shallow ditch 11 is an inverted trapezoid, with a height of 10-15 cm, an upper base width of 5-10 cm, a lower base width of 10-20 cm, and a length consistent with the length of the target field. To ensure that water flows from the beginning to the end of the field within the shallow ditch, a slope of 2°-6° is required from the beginning to the end of the field during the digging of the shallow ditch.

[0059] The water distribution pit 12 is connected to the shallow ditch 11 at the beginning of the field and is mainly used for distributing rinsing water. The depth of the water distribution pit 12 is consistent with the bottom depth of the shallow ditch 11 at the beginning of the field, the width of the water distribution pit 12 is consistent with the width of the actual planted field, and the length of the water distribution pit 12 is 1.0 to 1.2 m.

[0060] The spacing between the shallow trenches 11 is determined according to the spacing of the planted crops. The water storage tank 13 has an inlet near its top and two outlets near its bottom, designated as a first outlet and a second outlet. The first outlet is connected to a seepage pipe 14 via a rigid plastic tube, and the second outlet is connected to a water distribution pit 12 via a pipe 15. A water flow sensor 26 is installed on the second outlet, primarily used to record the total water output from the second outlet.

[0061] The seepage pipe 14 is a porous seepage pipe made of plastic or recycled rubber from waste tires. The seepage pipe 14 is buried 20-30 cm below the ground surface, with the specific burial depth determined by the root depth of the planted crop. The spacing between the seepage pipes 14 is determined by the spacing of the shallow trenches. The crop is planted directly above the seepage pipe 14, facilitating irrigation or desalination. To ensure that the buried seepage pipes are not crushed by planting equipment or human trampling, in this embodiment, a rigid material can be added to the outside of the seepage pipe 14 for fixation. To prevent the seepage pipe 14 from being blocked by soil particles during use, a layer of flexible metal mesh coated with plastic can be wrapped around the outside of the seepage pipe 14 to prevent direct contact between the seepage pipe 14 and the soil, reducing the risk of blockage of the permeable pores.

[0062] The rigid plastic pipe 15 is a plastic pipe directly connected to the seepage pipe 14. The rigid plastic pipe 15 includes a rigid plastic main pipe and a rigid plastic distribution pipe. There are two rigid plastic main pipes, which are vertically connected to the horizontally placed rigid plastic distribution pipes. The rigid plastic distribution pipes are horizontally arranged and have the same number of through holes as the seepage pipe 14. The connection between the rigid plastic main pipes and the rigid plastic distribution pipes is sealed with a sealing ring to ensure the system's airtightness. The air pump 16 is a conventional air pump that creates negative pressure inside the sealed container by extracting air from the container.

[0063] refer to Figure 6 The sedimentation tank 17 also includes an inlet 171, an outlet 172, an exhaust port 173, a triangular base 174, a turbidity sensor 175, and a hinge 176. The sedimentation tank 17 is generally rectangular, with dimensions of 1m in length, width, and height. The inlet 171 is a through-hole on the sedimentation tank, which is connected to the seepage pipe 14 via a pipe 15. When there is a working negative pressure inside the sedimentation tank, the seepage pipe 14, which is connected to the sedimentation tank via a second pipe, also experiences the same negative pressure. The second pipe can be pipe 15, allowing the rinsing waste liquid extracted from the seepage pipe 14 to enter the sedimentation tank through pipe 15.

[0064] The outlet 172 is another through-hole on the filter, mainly used to transport water from the sedimentation tank to the waste liquid tank 18 through the pipe 15. The vent 173 is a through-hole located near the top corner of the sedimentation tank, mainly connected to the air pump 16 through a rigid plastic pipe. The triangular base 174 is a wedge-shaped plastic plate, the length, width, and height of which are determined according to the length and width of the sedimentation tank, and the height is determined according to the height of the inlet. The turbidity sensor 175 is used to monitor particulate matter suspended in the water, mainly to determine whether the liquid in the sedimentation tank can be discharged into the waste liquid tank based on the feedback data. The hinge 176 is a fixing component that secures the detachable surface to the overall device. The detachable surface 177 is a side of the sedimentation tank without through-holes, which is fixed to the sedimentation tank 17 by the hinge 176, facilitating cleaning of the inside of the sedimentation tank 17 after the salt discharge system has finished operating. The detachable surfaces of the sedimentation tank are connected with sealing strips to ensure internal sealing.

[0065] The waste liquid tank 18 is a rectangular water collection tank with dimensions of 1×1×1.5m (length×width×height). According to the present invention, a root layer salt removal system and method based on a vacuum negative pressure porous infiltration pipe is provided. The field control system 2 includes: an instrument storage pile 21, a central processing unit 22, a first solenoid valve 23, a data transmission line 24, a soil water and salt sensor 25, a water flow sensor 26, and a second solenoid valve.

[0066] The instrument storage stud 21 is a storage component used to store some components. The central processing unit 22 is the core component of the control system, with functions such as inputting control thresholds, data comparison, data feedback, data signal conversion, and data storage. The first solenoid valve 23 is installed on the pipeline outlet of some components, realizing the closure and connection of the pipeline under the control of the central processing unit 22. The data transmission line 24 connects the wires of each component.

[0067] The soil water and salt sensor 25 consists of multiple time domain reflectometers buried at fixed vertical intervals. They are buried starting 5 to 10 cm below the soil surface, with the lowest time domain reflectometer buried at the same depth as the seepage pipe, and are used to measure soil water and salt data at different depths.

[0068] The central processing unit 22 controls the operation of the system based on data from the soil water and salt sensor 25. When the central processing unit 22 controls the operation of the irrigation system, it uses the average value of soil moisture data collected by all time-domain reflectometers in the soil water and salt sensor. When the central processing unit 22 controls the operation of the desalination system, it uses the average value of soil salinity data collected by all time-domain reflectometers in the soil water and salt sensor 25. The central processing unit 22 controls the opening and closing of the air pump 16 based on the soil moisture data collected by the lowest time-domain reflectometer in the soil water and salt sensor.

[0069] Multiple soil water and salt sensors 25 are buried between two infiltration pipes, with the buried positions of the multiple soil water and salt sensors 25 being in the middle of the central axis of the target field and at the end of the field. The water flow sensor 26 is installed on the pipe of the second outlet of the water storage tank, recording the amount of water flowing from the second outlet of the water storage tank 13.

[0070] The following describes the arrangement of a root zone salt drainage system and method based on a vacuum negative pressure porous infiltration pipe according to an embodiment of the present invention: First, a water distribution pit 12 is dug at the beginning of the field, with a length consistent with the width of the target field, a width of 10-20 cm, and a depth of 10-15 cm. Then, a shallow ditch 11 with a certain slope (2°-6°) is dug from the beginning to the end of the field. The length of the shallow ditch 11 is consistent with the length of the target field. The cross-section of the shallow ditch 11 is trapezoidal, with a height of 10-15 cm, an upper base width of 5-10 cm, and a lower base width of 10-20 cm. Subsequently, a freshwater source is connected to the inlet of a water storage tank 13 to replenish the water storage tank 13.

[0071] Subsequently, the infiltration pipe 14 is buried in the shallow trench 11 at a depth of 20-30 cm, depending on the root depth of the crop planted in the target field. Simultaneously, the soil water and salt sensor 25 is also buried along the central axis of the target field from the beginning to the end, specifically in the middle and end of the central axis. The soil water and salt sensor 25 is buried between two adjacent infiltration pipes 14 near the central axis of the target field, and its burial depth is consistent with that of the infiltration pipe 14.

[0072] After the infiltration pipe 14 and soil water and salt sensor 25 are installed, the control system is set up. An instrument storage stake 21 is inserted on the outermost ridge of the target field, and the central processing unit 22 is placed within it. The control program is imported into the central processing unit 22, and the data transmission lines 245 of the soil water and salt sensor 25 and the first solenoid valve are connected to the central processing unit 22. The central processing unit 22 processes the data collected by the soil water and salt sensor 25 in real time, compares and analyzes the processing results with the input control information, and then controls the first solenoid valve 23 to open and close, thereby connecting and disconnecting the pipeline.

[0073] The following describes the specific workflow of a root zone salt drainage system and method based on a vacuum negative pressure porous infiltration pipe, according to an embodiment of the present invention: After planting crops in the target field, irrigation is required. The soil moisture content at which irrigation begins is determined based on the drought tolerance limit of different crops, and irrigation is stopped when the soil moisture content reaches 70% to 75% of the field capacity of the target field. Table 1 lists the drought tolerance limits of some common crops grown in greenhouses. The relative soil moisture content in the table is the percentage of soil moisture content relative to the field capacity of the soil.

[0074] Table 1. Drought tolerance limits for some crops

[0075] Crop Name celery tomato Potato eggplant scallions Soil relative moisture content % 70～80 50～55 60～65 50～55 60～70

[0076] After crop planting, soil moisture sensors 25, buried in the target field, collect soil moisture data in real time and feed the data back to the central processing unit 22. After comparing and analyzing the data, the central processing unit 22 controls the system to irrigate. If the soil moisture data received by the central processing unit 22 from the soil moisture sensors 25 in the root zone reaches the lower limit of crop drought tolerance, the central processing unit 22 controls the first solenoid valve 23 to connect the pipeline, so that the water in the water storage tank 13 is distributed to each seepage pipe 14 through the first outlet and the pipeline. Irrigation stops when the soil moisture data fed back by the soil moisture sensors 25 in the root zone reaches between 70% and 75% of the field capacity of the target field.

[0077] The use of pesticides and fertilizers, root water absorption, and soil moisture evaporation can cause salt accumulation in shallow soil and upward migration of salt from deeper soil layers, resulting in a high-salt environment in the crop root zone. This causes salt stress on crop growth. To reduce the degree of stress, salt removal treatment needs to be implemented in the root zone. Table 2 provides the salt tolerance upper limits for some crops. When the soil salinity data fed back by the soil water and salt sensor 25 exceeds the salt tolerance upper limits provided in Table 2 for some crops, the central processing unit 22 controls the operation of the salt removal system.

[0078] Table 2 shows the upper limits of salt tolerance for some crops.

[0079] Crop Name celery tomato Potato eggplant scallions Total soluble salt content in soil (g / kg) 3.4 2.0 3.0 1.5 4.3

[0080] In this embodiment of the invention, the operation of the desalination system requires the irrigation system to be shut down beforehand. The switch between the irrigation system and the desalination system is achieved via the first solenoid valve 23. The central processing unit 22 controls the first solenoid valve 23 on the pipe connecting to the first outlet of the water storage tank to close, and the second solenoid valve on the rigid plastic main pipe connecting to the inlet 171 of the sedimentation tank to open, thus completing the system switch. If the central processing unit 22 is running the irrigation system before the system switch, after the irrigation system has finished running, the central processing unit 22 controls the first solenoid valve 23 on the first outlet of the water storage tank to close. If the irrigation system is not running before the system switch, the central processing unit 22 directly controls the first solenoid valve 23 on the rigid plastic main pipe 151 in front of the water storage tank to close, and the central processing unit 22 controls the second solenoid valve on the rigid plastic main pipe 151 connecting to the inlet 171 of the sedimentation tank to open.

[0081] In the embodiments of this invention, when the desalination system is running, if the crops in the target field are still growing, the central processing unit 22 will adopt an emergency rinsing strategy; if there are no crops growing in the target field, the central processing unit 22 will adopt a maintenance rinsing strategy.

[0082] In an embodiment of this invention, when the central processing unit 22 adopts an emergency rinsing strategy, it controls the opening of the first solenoid valve 23 in front of the second outlet of the water storage tank 13. Water from the storage tank 13 is injected into the distribution pit 12 through the second outlet, and the water in the distribution pit 12 flows to the end of the field along the slope of the shallow ditch 11. In this rinsing mode, the water flow sensor 26 is not required to monitor water volume data. When the soil moisture sensor 25 buried at the end of the field detects that the soil moisture data of the infiltration pipe 13 reaches the saturation water content of the target field soil, the central processing unit 22 controls the closing of the first solenoid valve 23 above the second outlet of the water storage tank 13. During the irrigation process of the target field, when the soil moisture content fed back by the soil moisture sensor 25 at the same burial depth as the infiltration pipe reaches the field capacity of the target field for the first time, the central processing unit 22 controls the start of the air pump 16. During the operation of the air pump, it is necessary to ensure that the negative pressure head generated is higher than 10% of the negative pressure head corresponding to the field capacity of the target field. The negative pressure intensity inside the sedimentation tank 17, connected to the air pump 16, gradually increases, thereby generating the same negative pressure intensity inside the seepage pipe 14. When the capillary suction of the soil around the seepage pipe 14 is lower than the negative pressure intensity inside the pipe, water around the pipe will enter the pipe through the pores of the seepage pipe 14, drawing the leachate out of the soil. The leachate extracted from the seepage pipe enters the sedimentation tank 17 through the inlet 171. The turbidity sensor 175 installed at the top of the sedimentation tank 17 can monitor particulate silt-like floating matter in the water. Based on the data fed back by the turbidity sensor 175, the central processing unit 22 controls the second solenoid valve at the drain outlet of the sedimentation tank to open, discharging the water in the sedimentation tank 17 into the waste liquid tank 18 for subsequent treatment. When the soil moisture content reported by the soil water and salt sensor 25 at the same burial depth as the seepage pipe 14 at the end of the field is lower than the field capacity of the target field, the central processing unit controls the air pump 16 to shut down and terminate the operation of the emergency leaching system.

[0083] In the embodiments of this invention, when the central processing unit 22 adopts a maintenance rinsing strategy, the total rinsing water volume is determined by the product of the total volume of the space directly above the bottom surface of all shallow ditches 11 and the corresponding infiltration pipes 14 and the soil saturation moisture content of the target field. The calculation formula is as follows:

[0084]

[0085] In the formula: Q is the amount of rinsing water required for maintenance rinsing, in m³. 3 n is the number of shallow ditches; h1 is the distance between the bottom depth of the shallow ditch at the beginning of the field and the burial depth of the seepage pipe, in meters; w1 is the width of the bottom of the shallow ditch at the beginning of the field, in meters; h2 is the distance between the bottom depth of the shallow ditch at the end of the field and the burial depth of the seepage pipe, in meters; w2 is the width of the bottom of the shallow ditch at the end of the field, in meters; L is the length of the target field, in meters; θ s It is the volumetric saturation water content of the soil in the target field.

[0086] The central processing unit 22 controls the opening of the first solenoid valve 23 above the second outlet of the water storage tank 13. The water flow sensor 26 above the second outlet of the water storage tank accurately records the amount of water flowing through and feeds it back to the central processing unit 22. When the water flow sensor 26 senses that the water volume has reached the set water volume threshold, it transmits a signal to close the first solenoid valve 23 to the central processing unit 22, which then controls the first solenoid valve 23 above the second outlet of the water storage tank 13 to close. The water flowing out of the second outlet of the water storage tank is directly injected into the water distribution pit 12, and the water flows into each shallow ditch 11.

[0087] During the process of watering the target field from the storage tank, when the soil moisture content, as indicated by the soil water and salt sensor 25 at the same burial depth as the seepage pipe 14, reaches the field capacity of the target field for the first time, the central processing unit 22 controls the air pump 16 to start. During the operation of the air pump, it is necessary to ensure that the negative pressure head it generates is 10% higher than the negative pressure head corresponding to the field capacity of the target field. The negative pressure intensity inside the sedimentation tank 17 connected to the air pump 16 gradually increases, thereby generating the same intensity of negative pressure inside the seepage pipe 14. When the capillary suction of the soil around the seepage pipe 14 is lower than the negative pressure intensity inside the pipe, water around the pipe will enter the pipe through the pores, drawing leachate out of the soil. The leachate extracted from the seepage pipe enters the sedimentation tank 17 through the inlet 171. A turbidity sensor 175 installed at the top of the sedimentation tank 17 can monitor particulate silt-like floating matter in the water. Based on the data fed back by the turbidity sensor 175, the central processing unit 22 controls the second solenoid valve at the drain outlet of the sedimentation tank to open, discharging the water in the sedimentation tank 17 into the waste liquid tank 18 for further treatment. When the soil moisture content fed back by the soil water and salt sensor 25 at the same burial depth as the seepage pipe 14 at the end of the field is lower than the field water holding capacity of the target field, the central processing unit 22 controls the air pump 16 to shut down and terminate the operation of the maintenance rinsing system.

[0088] After the desalination system has finished operating, the central processing unit will switch it back to the irrigation system and monitor and control the irrigation data. After the irrigation system is switched, the residual silt inside the sedimentation tank 17 needs to be cleaned. Open the hinge 176 on the removable surface 177, clean the accumulated silt inside with a tool, and then fix the hinge 176 again to prepare for the next operation of the desalination system.

[0089] The water storage tank 13, seepage pipe 14, pipeline 15, air pump 16, sedimentation tank 17, triangular base 174, turbidity sensor 175, hinge 176, detachable panel 177, waste liquid tank 18, instrument storage pile 21, central processing unit 22, first solenoid valve 23, data transmission line 24, soil water and salt sensor 25, and water flow sensor 26 are all available in the prior art. Those skilled in the art can select according to actual needs. No examples will be given in this embodiment.

[0090] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0091] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention described herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0092] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", "joining", and "fitting" should be interpreted broadly, and can refer to mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0093] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. The above specific embodiments have further described the purpose, technical solution and beneficial effects of this application in detail. It should be understood that the above are only specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solution of this application should be included within the scope of protection of this application.

Claims

1. A root zone salt removal method based on vacuum negative pressure porous permeable pipes, characterized in that, A root layer salt drainage system based on vacuum negative pressure porous infiltration pipes is used. The system includes an irrigation and drainage system (1) and a field control system (2), which is installed on the irrigation and drainage system (1). The irrigation and drainage system (1) includes shallow ditches (11), water distribution pits (12), water storage tanks (13), several seepage pipes (14), pipes (15) and a first solenoid valve (23). The target field is provided with water distribution pits (12) and several shallow ditches (11) arranged at equal intervals. Seepage pipes (14) are laid in the several shallow ditches (11) arranged at equal intervals. The water storage tank (13) is connected to the seepage pipes (14) and the water distribution pits (12) through pipes (15). The first solenoid valve (23) is installed on the pipes (15). The irrigation and drainage system (1) also includes a second pipe, a second solenoid valve, an air pump (16), a sedimentation tank (17) and a waste liquid tank (18). The air pump (16) is connected to the sedimentation tank (17). The sedimentation tank (17) is connected to the seepage pipe (14) through the second pipe. The second solenoid valve is installed on the second pipe. The sedimentation tank (17) is connected to the waste liquid tank (18). The field control system (2) includes an instrument storage pile (21), a central processing unit (22), a data transmission line (24), and a soil water and salt sensor (25). The central processing unit (22) is installed on the instrument storage pile (21), and the central processing unit (22) is connected to the soil water and salt sensor (25) through the data transmission line (24). The field control system (2) also includes a water flow sensor (26), which is installed on the pipe (15) and connected to the central processing unit (22); The first solenoid valve (23) and the second solenoid valve are connected to the central processing unit (22); The sedimentation tank (17) includes a sedimentation tank frame, an inlet (171), an outlet (172), an exhaust port (173), a triangular base (174), a turbidity sensor (175), a hinge (176), and a detachable surface (177). The triangular base (174) is fixedly installed at the bottom inside the sedimentation tank frame, the turbidity sensor (175) is fixedly installed at the top inside the sedimentation tank frame, and the detachable surface (177) is installed on the sedimentation tank frame via the hinge (176). The bottom of the shallow ditch (11) has a slope of 2°~6° from the beginning to the end of the field, and the bottom of the ditch at the beginning of the field is higher than the bottom of the ditch at the end of the field. The method performs the following steps: If the crops in the target field are still growing, an emergency rinsing strategy is adopted using the central processor (22); If no crops are growing in the target field, a maintenance rinsing strategy is adopted using the central processor (22); Maintenance rinsing strategies include: Calculate the total amount of water used for rinsing: ； In the formula: Q is the amount of water required for maintenance leaching; n is the number of shallow ditches; h1 is the distance between the bottom depth of the beginning of the shallow ditch (11) and the burial depth of the infiltration pipe (14); w1 is the width of the bottom of the beginning of the shallow ditch (11); h2 is the distance between the bottom depth of the end of the shallow ditch (11) and the burial depth of the infiltration pipe; w2 is the width of the bottom of the end of the shallow ditch (11); L is the length of the target field; θ s It is the volumetric saturation water content of the soil in the target field; The central processing unit (22) controls the opening of the first solenoid valve (23), and the water flow sensor (26) accurately records the amount of water flowing through the first solenoid valve (23) and feeds it back to the central processing unit (22); When the water flow sensor (26) senses that the water flow through the first solenoid valve (23) has reached the set water flow threshold, the central processing unit (22) controls the first solenoid valve (23) to close. The water flowing out of the storage tank (13) is injected into the water distribution pit (12) and then flows into each shallow ditch (11); When the soil moisture content fed back by the soil water and salt sensor (25) reaches the field water holding capacity of the preset target field for the first time, the central processing unit (22) controls the air pump (16) to start, and the negative pressure intensity in the sedimentation tank (17) gradually increases, thereby generating the same intensity of negative pressure inside the seepage pipe (14). When the capillary water suction of the soil around the seepage pipe (14) is lower than the negative pressure intensity inside the seepage pipe (14), the water around the seepage pipe (14) enters the seepage pipe (14), and the seepage pipe (14) is used to extract the leached water from the soil. The leachate extracted by the seepage pipe (14) enters the sedimentation tank (17) through the inlet (171); The turbidity sensor (175) was used to monitor particulate silt-like floating matter in the leachate in the precipitator (17); Based on the data of particulate silt floating matter fed back by the turbidity sensor (175), the central processing unit (22) controls the second solenoid valve to open and discharge the leachate in the sedimentation tank (17) into the waste liquid tank (18). When the soil moisture content reported by the soil water and salt sensor (25) is lower than the field water holding capacity of the preset target field, the central processing unit (22) controls the air pump (16) to shut down.

2. The root zone salt removal method based on vacuum negative pressure porous permeable pipes according to claim 1, characterized in that, Emergency rinsing strategies include: The central processing unit (22) controls the opening of the first solenoid valve (23), and the water in the water storage tank (13) is injected into the water distribution pit (12). Inside, the water in the water distribution pit (12) flows to the end of the field along the shallow ditch (11); If the soil water and salt sensor (25) buried at the end of the field detects that the soil moisture data around the seepage pipe (14) reaches the preset target field soil saturation water content, the central processing unit (22) controls the first solenoid valve (23) to close. When the soil water and salt sensor (25) at the same burial depth as the field end and the seepage pipe (14) first reaches the field water holding capacity of the preset target field, the central processing unit (22) controls the air pump (16) to start, and the negative pressure intensity in the sedimentation tank (17) connected to the air pump (16) gradually increases, thereby generating the same intensity of negative pressure inside the seepage pipe (14). When the capillary water suction of the soil around the seepage pipe (14) is lower than the negative pressure intensity inside the seepage pipe (14), the water around the seepage pipe (14) enters the seepage pipe (14), and the seepage pipe (14) is used to extract the leached water from the soil. The leachate extracted by the seepage pipe (14) enters the sedimentation tank (17). The turbidity sensor (175) monitors the data of particulate mud and sand floating matter in the leachate in the sedimentation tank (17). The central processing unit (22) controls the second solenoid valve to open and discharge the water in the sedimentation tank (17) into the waste liquid tank (18). When the soil moisture content reported by the soil water and salt sensor (25) is lower than the field water holding capacity of the preset target field, the central processing unit (22) controls the air pump (16) to shut down.

3. The root zone salt removal method based on vacuum negative pressure porous permeable pipes according to claim 1, characterized in that, After the crop is planted, soil moisture data is collected in real time using a soil water and salt sensor (25) and fed back to the central processing unit (22); If the central processing unit (22) receives soil moisture data from the soil water and salt sensor (25) that reaches the preset crop drought tolerance limit, the central processing unit (22) controls the first solenoid valve (23) to open, so that water in the water storage tank (13) flows into each seepage pipe (14) until the soil moisture data fed back by the soil water and salt sensor (25) reaches 70% to 75% of the field water holding capacity of the preset target field, at which point the first solenoid valve (23) is closed.

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