Water salinity stratification control irrigation device for saline-alkali land rice-wheat intercropping

Abstract

The application relates to the technical field of saline-alkali soil improvement, in particular to a water and salt layering control irrigation device for rice-wheat intercropping in saline-alkali soil, which solves the problems of serious water resource waste caused by traditional flood irrigation, incomplete salt washing in the rice season, easy salt return in the wheat season, lack of vertical profile water and salt data support leading to lagging control, and the like; the device comprises a shallow soil layer, a deep soil layer, a ridge and a surface layer, a PLC controller is arranged on one side of the ridge, and a water collecting tank is arranged in the inside of the ridge; the device further comprises a layered double-control irrigation and drainage pipe network assembly, a multi-soil-layer in-situ water and salt sensing unit and a buried pipe salt drainage module. The device realizes directional surface layer leaching and salt removal in the rice season, deep layer precise water supply and salt return inhibition in the wheat season, and efficient salt drainage through the synergistic work of the double-control pipe network of surface layer leaching and deep layer water supply, the multi-soil-layer in-situ water and salt sensing unit and the buried pipe salt drainage module, the system intelligently controls according to the soil water and salt data, the water and salt contradiction is solved, the water resource utilization rate is improved, and high yield and stable yield of rice-wheat rotation are ensured.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land improvement technology, specifically to a water and salt stratified irrigation device for rice-wheat intercropping in saline-alkali land. Background Technology

[0002] Saline-alkali land is an important reserve of arable land in my country, and its improvement and efficient utilization are of great significance to ensuring national food security. In saline-alkali areas, the rice-wheat intercropping model has been widely promoted because it can make full use of water resources and improve land productivity. However, there is a significant contradiction between the soil water and salt environment requirements of the rice planting season and the wheat planting season: the rice season requires a large amount of water to wash away salt and reduce the salinity of the topsoil; while the wheat season requires control of groundwater level and soil moisture to prevent the salt accumulated in the bottom layer from seeping upward through capillary action, which would lead to secondary salinization of the topsoil and affect wheat emergence and growth.

[0003] In the rice-wheat intercropping model on saline-alkali land, there is a significant contradiction between the water and salt requirements of rice for salt leaching and desalination and wheat for preventing salt return; existing technologies mainly have the following core defects: 1. Traditional irrigation methods often employ flood irrigation or single-depth water supply, which cannot achieve surface leaching during the rice season while effectively blocking the capillary rise and salt return of deep groundwater during the wheat season. This "one-size-fits-all" water supply method makes it difficult to completely remove salt accumulation in the topsoil and easily leads to secondary salinization of the topsoil during the wheat season, making it difficult to meet the differentiated water and salt environment requirements within the crop rotation cycle.

[0004] 2. Existing monitoring methods are mostly manual sampling or shallow fixed-point detection, lacking in-situ synchronous perception of water and salt dynamics at different depths of soil profile (shallow soil layer and deep soil layer); due to the inability to obtain vertical water and salt distribution data in real time, irrigation decisions often rely on experience, resulting in lagging regulation and difficulty in achieving coordinated water and salt management.

[0005] 3. The irrigation and drainage systems in the existing equipment are relatively independent and lack an intelligent linkage mechanism based on water and salt data; the efficiency of salt wastewater discharge during rice washing is low and salt retention is easy to occur; during wheat season, due to the lack of precise water control measures, ineffective irrigation is often caused, resulting in low water resource utilization and the inability to effectively cut off the salt return channel.

[0006] 4. In addition, traditional methods of saline-alkali land improvement are highly dependent on natural climate conditions and are significantly constrained by ambient temperature. Whether relying on natural drying or biological improvement by planting salt-tolerant crops, the desalination cycle is relatively long and easily extended by adverse weather conditions such as low temperatures and rain. However, under the rice-wheat intercropping model, the effective agricultural window left for land improvement and rice preparation after wheat harvest is extremely short. Once the salt washing process is hindered or takes too long due to weather conditions, it is very easy to squeeze out the precious transplanting time, causing farmers to miss the optimal rice sowing period, resulting in reduced yields or even abandonment of cultivation.

[0007] In summary, existing technologies have significant shortcomings in resolving the water and salt imbalance in rice-wheat intercropping, achieving precise vertical stratification and control, and improving resource utilization efficiency. There is an urgent need for a new type of irrigation device with stratified dual control, in-situ sensing, and intelligent linkage functions. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides a water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land. It has the advantages of independent and precise regulation of surface leaching and deep water supply, in-situ real-time dynamic sensing of water and salt in multiple soil layers, and intelligent linkage and coordination of irrigation and drainage systems. It solves the problems of serious water waste caused by traditional flood irrigation, incomplete salt leaching during the rice season which easily leads to salt return during the wheat season, and lagging regulation due to lack of vertical profile water and salt data support.

[0010] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land, comprising a shallow soil layer, a deep soil layer, field ridges and a surface layer, wherein the deep soil layer is located at the bottom of the shallow soil layer, the field ridges are set on one side of the shallow soil layer and the deep soil layer, the surface layer is set on the surface of the shallow soil layer, a PLC controller is installed on one side of the field ridge, a solar panel is installed on the top of the PLC controller, and a water collection trough is set inside the field ridge; It also includes a layered dual-control irrigation and drainage network component, a multi-soil layer in-situ water and salt sensing unit, and a buried pipe salt drainage module.

[0011] Preferably, the layered dual-control irrigation and drainage network assembly includes a surface rinsing network, a deep root system water supply network, a water supply pipe, a surface control valve, a deep control valve, a filter assembly, and a pump body. The surface rinsing network is installed in the shallow soil layer and includes multiple embedded drip irrigation tapes and adapter drip irrigation tape assemblies. Both ends of the adapter drip irrigation tapes are fixedly connected to one end of the multiple embedded drip irrigation tapes via flanges. The deep root system water supply network is installed in the deep soil layer, and a water supply pipe is installed between the deep root system water supply network and one end of the surface rinsing network via a flange. The surface control valve and the deep control valve are both fixedly installed on one side of the water supply pipe. The outlet of the pump body is connected to one end of the water supply pipe, and the other end is installed with the filter assembly.

[0012] Preferably, the filtration assembly includes a centrifugal sand separator, a disc filter, and a fully automatic backwashing control system. The centrifugal sand separator, the disc filter, and the fully automatic backwashing control system are interconnected, and the inlet of the fully automatic backwashing control system extends into the interior of the water collection tank.

[0013] Preferably, the multi-soil layer in-situ water and salt sensing unit includes multiple mounting slots located between shallow and deep soil layers. Each mounting slot contains a PVC sensing rod. Four mounting blocks are fixedly mounted on the surface of each PVC sensing rod. A soil volumetric water content sensor, a soil conductivity sensor, and a temperature sensor are fixedly mounted on the outer surface of each mounting block. The gaps between the mounting slots and the PVC sensing rods are filled with fine sand. A support frame is mounted on the surface of the field ridge. A number of junction boxes, matching the number of PVC sensing rods, are mounted on the surface of the support frame. Each junction box contains a data acquisition module and a data transmission module. A rain cover is fixedly mounted on the surface of the support frame and located on top of the junction boxes.

[0014] Preferably, the underground pipe desalination module includes an underground structure located at the bottom of the deep soil layer. The underground structure includes backfill soil, a gravel filter material layer, a non-woven geotextile, a perforated corrugated pipe, and a gravel cushion layer at the bottom of the trench, arranged in sequence at the bottom of the deep soil layer. One end of the perforated corrugated pipe is fixedly installed with a water outlet pipe extending into the water collection tank via a flange.

[0015] Preferably, the surface irrigation network is buried in the shallow soil layer at a depth of 20-30cm below the surface, and multiple embedded drip irrigation tapes are laid parallel to each other along the width of the shallow soil layer, with a spacing of 40-50cm between adjacent embedded drip irrigation tapes. The deep root water supply network is buried in the deep soil layer at a depth of 60-80cm below the surface layer. The surface control valve is located at one end of the water supply pipe near the surface rinsing network, and the deep control valve is located at one end of the water supply pipe near the deep root water supply network. The horizontal distance between the surface control valve and the deep control valve on the water supply pipe is greater than 50cm.

[0016] Preferably, multiple PVC sensing rods are vertically inserted into the mounting groove, with their tops extending 5cm to 10cm above the surface of the shallow soil layer. Multiple soil volumetric moisture sensors, soil conductivity sensors, and temperature sensors are fixed on the PVC sensing rods at positions 10cm, 30cm, 60cm, and 80cm from the bottom of the rod, respectively. Multiple data acquisition modules are electrically connected to the sensors on the four mounting blocks via wires. Multiple data transmission modules are located above the data acquisition modules and are connected to the PLC controller via wireless signals or cables.

[0017] Preferably, the diameter of the perforated corrugated pipe is about 110 mm, and its outer wall is evenly distributed with circular through holes with a diameter of 3-5 mm. The non-woven geotextile is wrapped around the outer periphery of the perforated corrugated pipe, the crushed stone filter material layer is filled between the non-woven geotextile and the backfill soil, and the thickness of the crushed stone cushion layer at the bottom of the ditch is 10-15 cm. The water outlet pipe extends downward at an angle from one end of the perforated corrugated pipe to the bottom of the water collection trough.

[0018] Preferably, the output terminal of the PLC controller is electrically connected to the surface control valve, the deep control valve, the pump body, the fully automatic backwash control system, and multiple data transmission modules, respectively, and the output terminal of the solar panel is electrically connected to the battery pack inside the PLC controller through a charging controller.

[0019] (III) Beneficial Effects

[0020] Compared with the prior art, the present invention provides a water and salt stratified irrigation device for rice-wheat intercropping in saline-alkali land, which has the following beneficial effects: 1. This invention constructs a dual-control irrigation and drainage system with an independent and parallel surface rinsing pipe network and a deep root water supply network, and in conjunction with a layered control valve group, it realizes differentiated regulation of surface directional rinsing desalination in the rice season and deep precise water supply to suppress salt return in the wheat season, effectively solving the technical problems of "incomplete salt rinsing" and "severe salt return in the wheat season" caused by traditional single deep irrigation.

[0021] 2. This invention overcomes the shortcomings of existing monitoring methods, such as lagging and lack of vertical profile data, by burying multi-parameter sensing units in situ at key depths in shallow and deep soil layers, and synchronously collecting soil volumetric water content, electrical conductivity and temperature data in real time and transmitting them to the PLC controller. This provides accurate real-time decision-making basis for water and salt synergistic management.

[0022] 3. This invention intelligently links the underground pipe salt drainage module with the water collection tank, and utilizes the efficient drainage structure of the perforated corrugated pipe and the crushed stone filter material layer to quickly discharge the leaching saline wastewater during the rice season and accurately control the groundwater level during the wheat season, thus solving the problems of salt retention and water waste caused by the independent operation of traditional irrigation and drainage systems.

[0023] 4. This invention abandons the traditional model of relying on natural evaporation or long-term biological improvement. Through the active hydraulic linkage between the pump and the underground pipe salt discharge system, it can complete high-intensity salt washing operations in a short time (such as several days). This process completely eliminates the dependence on continuous sunny and hot weather. Even under unfavorable climatic conditions such as low temperature and rain, the salt washing efficiency can be guaranteed to remain unaffected. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural view of the water and salt stratification regulation irrigation device for rice-wheat intercropping in saline-alkali land according to the present invention. Figure 2 This is a three-dimensional view of the layered dual-control irrigation and drainage pipe network component structure of the present invention; Figure 3 This is a schematic diagram of the installation of the multi-soil layer in-situ water and salt sensing unit structure of the present invention; Figure 4 This is a top view of the perforated corrugated pipe structure of the present invention. Figure 5This is a perspective view of the installation structure of the PVC sensing rod, mounting block, soil volumetric moisture sensor, soil conductivity sensor, and temperature sensor of the present invention. Figure 6 For the present invention Figure 1 Enlarged view of the structure at point A in the middle.

[0025] In the diagram: 1. Shallow soil layer; 2. Deep soil layer; 3. Field ridge; 4. Water collection trough; 5. PLC controller; 6. Solar panel; 7. Layered dual-control irrigation and drainage network assembly; 71. Surface washing network; 711. Embedded drip irrigation tape; 712. Adaptor drip irrigation tape; 72. Deep root water supply network; 73. Water supply pipe; 74. Surface control valve; 75. Deep control valve; 76. Filter assembly; 761. Centrifugal sand separator; 762. Disc filter; 763. Fully automatic backwash control system; 77. Pump body; 8. Multi-layer in-situ water and salt sensing unit; 81. Mounting groove; 82. PVC sensing rod; 83. Mounting block; 84. Soil volumetric water content sensor; 85. Soil conductivity sensor; 86. Temperature sensor; 87. Fine sand; 88. Bracket; 89. Junction box; 891. Data acquisition module; 892. Data transmission module; 80. Rain cover; 9. Concealed pipe salt drainage module; 91. Underground; 92. Backfill soil; 93. Crushed stone filter layer; 94. Non-woven geotextile; 95. Perforated corrugated pipe; 96. Crushed stone cushion layer at the bottom of the trench; 97. Drainage pipe; 10. Surface layer. Detailed Implementation

[0026] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figures 1-6 As shown, the water and salt stratified regulation irrigation device for rice and wheat intercropping in saline-alkali land includes a shallow soil layer 1, a deep soil layer 2, field ridges 3, and a surface layer 10. The deep soil layer 2 is located at the bottom of the shallow soil layer 1. The field ridges 3 are set on one side of the shallow soil layer 1 and the deep soil layer 2. The surface layer 10 is set on the surface of the shallow soil layer 1. A PLC controller 5 is installed on one side of the field ridges 3. A solar panel 6 is installed on the top of the PLC controller 5. A water collection tank 4 is set inside the field ridges 3. It also includes a stratified dual-control irrigation and drainage network assembly 7, a multi-soil layer in-situ water and salt sensing unit 8, and a hidden pipe salt drainage module 9.

[0028] like Figure 1 , Figure 2As shown, the layered dual-control irrigation and drainage network assembly 7 uses the pump body 77 as its power core, and its outlet end is connected in series with the filter assembly 76. Among them, the centrifugal sand remover 761 is used to initially remove silt and impurities in the water, the disc filter 762 performs fine filtration to ensure the smooth flow of the drip irrigation system, and the fully automatic backwash control system 763 uses the saline wastewater collected in the water collection tank 4 as the backwash water source to realize the automatic regeneration and cleaning of the filter media. The filtered clean water flows through the water supply pipe 73 to the branch node, and is controlled by the surface control valve 74 and the deep control valve 763. The independent opening and closing logic of valve 75 accurately distributes water flow to the surface irrigation network 71 buried in the shallow soil layer 1 and the deep root water supply network 72 buried in the deep soil layer 2. The surface irrigation network 71 is composed of multiple embedded drip irrigation tapes 711, which are tightly connected by flanges through adapter drip irrigation tapes 712 to form a mesh covering structure, ensuring that water penetrates evenly to the surface of the cultivated layer. The deep root water supply network 72 is independently arranged in the main distribution area of ​​the crop roots. The two are completely isolated in physical space, and hydraulic switching is only achieved at the water supply pipe 73 through a valve.

[0029] It should be noted that the fully automatic backwashing control system 763 is a mature existing technology. Its core lies in monitoring the pressure changes before and after the disc filter 762 in real time through a built-in differential pressure sensor or timer counter. Once the differential pressure exceeds the preset threshold or reaches the set time, the system will automatically trigger the switching logic.

[0030] In this embodiment, the PLC controller intelligently schedules the surface control valve 74 and the deep control valve 75 based on soil water and salt monitoring data: During the rice season salt leaching stage, the surface control valve 74 is opened and the deep control valve 75 is closed, allowing a large amount of fresh water to perform high-intensity rinsing only on the shallow soil layer 1, while the salt drainage module 9 in the underground pipe promptly discharges saline wastewater; During the wheat season anti-salt return stage, the operation is reversed, the surface control valve 74 is closed and the deep control valve 75 is opened, providing only a suitable amount of water to the deep soil layer 2 to maintain crop growth, while cutting off the shallow capillary water channels to prevent the upward movement of bottom salts; The advantage of this layered independent water supply is that it completely solves the problem of incomplete salt leaching or severe salt return caused by the traditional "one-size-fits-all" irrigation, significantly improves water resource utilization, avoids secondary salinization caused by ineffective evaporation of deep groundwater, and the fully automatic backwashing function effectively extends the service life of the filter component 76, ensuring the stable operation of the system in a long-term high-salinity, high-silt environment.

[0031] like Figure 1 , Figure 3 and Figure 5As shown, the multi-layer in-situ water and salt sensing unit 8 adopts a vertical profile layered monitoring architecture. Multiple mounting slots 81 are pre-set in the area where the shallow soil layer 1 and the deep soil layer 2 meet, and PVC sensing rods 82 are vertically embedded in them. Fine sand 87 is used to fill the gap between the rod and the slot wall to optimize heat conduction and prevent soil compaction from affecting contact. Four mounting blocks 83 are fixed at intervals along the depth direction on the surface of each PVC sensing rod 82, on which soil volumetric water content sensor 84, soil conductivity sensor 85, and temperature sensor 86 are integrated respectively. The sensor probes are precisely positioned... Located at key depth nodes 10cm, 30cm, 60cm, and 80cm from the bottom of the pole, a three-dimensional sensing network of "shallow-medium-shallow-deep soil-deep" is formed. The sensor data is collected through wires to the junction box 89 on the support 88 of the field ridge 3. The data acquisition module 891 performs analog-to-digital conversion and preliminary processing, and then transmits the data back to the PLC controller 5 in real time via wireless or wired means through the data transmission module 892 located above. The entire sensing system is covered with a rain cover 80 to resist the harsh outdoor environment and ensure the stability of long-term operation.

[0032] like Figure 1 , Figure 4 and Figure 6 As shown, the underground drainage module 9 is constructed at the bottom of the deep soil layer 2. Its core structure, the "underground drainage ditch 91," adopts a multi-layer composite filtration and diversion design: a 10-15cm thick gravel cushion layer 96 is first laid at the bottom of the ditch as a foundation support and initial water collection layer. Then, non-woven geotextile 94, gravel filter material layer 93, and backfill soil 92 are sequentially installed upwards. The perforated corrugated pipe 95 serves as the main drainage channel and is horizontally buried in the center of the gravel filter material layer 93. Its outer perimeter is tightly wrapped with non-woven geotextile 94 to prevent soil particles from entering. At the same time, it prevents fine sand 87 from clogging; the diameter of the perforated corrugated pipe 95 is set at 110mm, and the pipe wall is evenly distributed with 3-5mm circular through holes to ensure that deep groundwater and the saline water after leaching can efficiently seep into the pipe; the module fixes the outlet pipe 97 to one end of the perforated corrugated pipe 95 through the flange connection, and makes it extend downward through the field ridge 3, and finally into the bottom of the water collection trough 4, forming a complete gravity flow drainage path from the deep part of the field to the surface water collection, and the materials of each layer are tightly bonded and there are no gaps or leaks.

[0033] In this embodiment, the underground pipe salt drainage module 9 utilizes the pressure difference and gravity at the bottom of the deep soil layer 2. When surface leaching is carried out during the rice season or groundwater level needs to be controlled during the wheat season, the salt-rich groundwater is collected through the gravel cushion layer 96 at the bottom of the ditch. After preliminary filtration by the gravel filter material layer 93, it enters the pipe through the circular through-hole of the perforated corrugated pipe 95. Then, the non-woven geotextile 94 acts as a barrier to intercept sediment. Finally, it flows by gravity along the outlet pipe 97 to the collection tank 4 for centralized treatment or discharge. By constructing an efficient "deep salt interception" barrier, the groundwater level can be effectively lowered, the capillary water rise channel can be cut off, and the path of deep salt migration to the cultivated layer can be completely blocked, solving the problem of salt return during the wheat season. At the same time, the multi-level filtration structure (gravel cushion layer + non-woven geotextile + gravel filter material) greatly extends the service life of the underground pipe, prevents blockage, and ensures the smoothness and stability of the long-term salt drainage system, realizing the high efficiency and long-term effectiveness of the "salt drainage" link in saline-alkali land improvement.

[0034] In this embodiment, the PLC controller 5 serves as the core control unit. Its output terminals are electrically connected to the surface control valve 74 and the deep control valve 75 to precisely regulate the water flow path, drive the pump 77 to start and stop, adjust irrigation parameters, and link with the fully automatic backwash control system 763 to automatically perform filtration and cleaning. At the same time, it receives monitoring data from multiple data transmission modules 892 to achieve closed-loop decision-making. The solar panel 6 supplies power to the system battery pack via the charging controller, ensuring that the PLC controller 5 and all execution and sensing components operate stably around the clock even when there is no mains power.

[0035] It should be noted that the saline wastewater in the water collection tank 4 adopts the strategy of "ecological utilization / discharge during the day and deep discharge at night": during the day, the wastewater is transported to the salt-tolerant plant area for purification or discharged into the ditch; at night, it automatically switches to the underground pipe salt discharge module 9, which directly injects the wastewater below the deep groundwater level, using the high water conductivity at night to accelerate salt discharge and prevent surface evaporation and salt return.

[0036] The working process of this water and salt stratification control irrigation device for rice-wheat intercropping in saline-alkali land begins with the multi-layer in-situ water and salt sensing unit 8 collecting data in real time from soil volumetric water content sensors 84, soil conductivity sensors 85, and temperature sensors 86 at different depths (10cm, 30cm, 60cm, and 80cm) in the shallow soil layer 1 and deep soil layer 2. This data is then processed by the data acquisition module 891 in the junction box 89 and transmitted to the PLC controller 5. The controller makes intelligent decisions based on preset strategies or real-time monitoring results: during the rice season salt leaching stage, the pump 77 is activated to drive water flow through the filtration assembly 76, which includes a centrifugal sand remover 761, a disc filter 762, and a fully automatic... After purification by the backwash control system 763, the surface control valve 74 is opened and the deep control valve 75 is closed through the water supply pipe 73, so that fresh water can be used to perform high-intensity rinsing on the shallow soil layer 1 only through the surface rinsing pipe network 71. At the same time, the perforated corrugated pipe 95 in the underground pipe salt discharge module 9 is used to collect the salt water and then gravity-guide the salt water to the collection tank 4 through the outlet pipe 97 for discharge. During the wheat season salt prevention stage, the operation is reversed, the surface control valve 74 is closed and the deep control valve 75 is opened, and water is supplied only to the deep root water supply network 72 to maintain crop growth and cut off the shallow capillary water channel, thus forming a closed-loop automated control system of "sensing-decision-layered irrigation-directional salt discharge".

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water and salt stratified irrigation device for rice-wheat intercropping in saline-alkali land, comprising a shallow soil layer (1), a deep soil layer (2), field ridges (3), and a surface layer (10), characterized in that: The deep soil layer (2) is located at the bottom of the shallow soil layer (1), the field ridge (3) is set on one side of the shallow soil layer and the deep soil layer (2), the surface layer (10) is set on the surface of the shallow soil layer (1), a PLC controller (5) is installed on one side of the field ridge (3), a solar panel (6) is installed on the top of the PLC controller (5), and a water collection trough (4) is set inside the field ridge (3). It also includes a layered dual-control irrigation and drainage network component (7), a multi-soil layer in-situ water and salt sensing unit (8), and a hidden pipe salt drainage module (9).

2. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 1, characterized in that: The layered dual-control irrigation and drainage network assembly (7) includes a surface rinsing network (71), a deep root water supply network (72), a water supply pipe (73), a surface control valve (74), a deep control valve (75), a filter assembly (76), and a pump body (77). The surface rinsing network (71) is installed in the shallow soil layer (1), and the surface rinsing network (71) includes multiple embedded drip irrigation tapes (711) and adapter drip irrigation tapes (712) assemblies. Both ends of the adapter drip irrigation tapes (712) are connected to the multiple embedded drip irrigation tapes (711) via flanges. One end of the embedded drip irrigation tape (711) is fixedly connected. The deep root water supply network (72) is installed in the deep soil layer (2). A water supply pipe (73) is installed between the deep root water supply network (72) and one end of the surface rinsing pipe network (71) via a flange. The surface control valve (74) and the deep control valve (75) are both fixedly installed on one side of the water supply pipe (73). The outlet of the pump body (77) is connected to one end of the water supply pipe (73), and the other end is installed with the filter assembly (76).

3. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 2, characterized in that: The filter assembly (76) includes a centrifugal sand remover (761), a disc filter (762), and a fully automatic backwash control system (763). The centrifugal sand remover (761), the disc filter (762), and the fully automatic backwash control system (763) are interconnected, and the inlet of the fully automatic backwash control system (763) extends into the interior of the water collection tank (4).

4. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 1, characterized in that: The multi-soil layer in-situ water and salt sensing unit (8) includes multiple mounting slots (81) located between the shallow soil layer (1) and the deep soil layer (2). Each mounting slot (81) has a PVC sensing rod (82) installed inside it. Four mounting blocks (83) are fixedly mounted on the surface of each PVC sensing rod (82). Each mounting block (83) has a soil volumetric water content sensor (84), a soil conductivity sensor (85), and a temperature sensor (86) fixedly mounted on its outer surface. The gap between the groove (81) and the PVC sensor rod (82) is filled with fine sand (87). A bracket (88) is installed on the surface of the field ridge (3). A junction box (89) with the same number as the multiple PVC sensor rods (82) is installed on the surface of the bracket (88). A data acquisition module (891) and a data transmission module (892) are installed inside each junction box (89). A rain cover (80) is fixedly installed on the surface of the bracket (88) and located on top of the multiple junction boxes (89).

5. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 1, characterized in that: The underground pipe salt drainage module (9) includes an underground (91) located at the bottom of the deep soil layer (2). The underground (91) includes backfill soil (92), crushed stone filter material layer (93), non-woven geotextile (94), perforated corrugated pipe (95) and crushed stone cushion layer (96) arranged sequentially at the bottom of the deep soil layer (2). One end of the perforated corrugated pipe (95) is fixedly installed with a water outlet pipe (97) extending into the water collection tank (4) via a flange.

6. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 2, characterized in that: The surface rinsing network (71) is buried in the shallow soil layer (1) at a depth of 20-30cm below the surface layer (10), and multiple embedded drip irrigation tapes (711) are laid parallel to each other along the width direction of the shallow soil layer (1), with a spacing of 40-50cm between two adjacent embedded drip irrigation tapes (711). The deep root water supply network (72) is buried in the deep soil layer (2) at a depth of 60-80cm below the surface layer (10). The surface control valve (74) is located at one end of the water supply pipe (73) near the surface rinsing network (71). The deep control valve (75) is located at one end of the water supply pipe (73) near the deep root water supply network (72). The horizontal distance between the surface control valve (74) and the deep control valve (75) on the water supply pipe (73) is greater than 50cm.

7. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 4, characterized in that: Multiple PVC sensing rods (82) are vertically inserted into the mounting groove (81), with their tops extending 5cm to 10cm above the surface of the shallow soil layer (1). Multiple soil volumetric water content sensors (84), soil conductivity sensors (85), and temperature sensors (86) are fixed on the PVC sensing rods (82) at positions 10cm, 30cm, 60cm, and 80cm from the bottom of the rod, respectively. Multiple data acquisition modules (891) are electrically connected to the sensors on the four mounting blocks (83) via wires. Multiple data transmission modules (892) are located above the data acquisition modules (891) and connected to the PLC controller (5) via wireless signals or cables.

8. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claim 5, characterized in that: The diameter of the perforated corrugated pipe (95) is about 110 mm, and its outer wall is evenly distributed with circular through holes with a diameter of 3-5 mm. The non-woven geotextile (94) is wrapped around the outer periphery of the perforated corrugated pipe (95). The crushed stone filter layer (93) is filled between the non-woven geotextile (94) and the backfill soil (92). The thickness of the crushed stone cushion layer (96) at the bottom of the ditch is 10-15 cm. The water outlet pipe (97) is led out from one end of the perforated corrugated pipe (95) and extends downward at an angle to the bottom of the water collection trough (4).

9. The water and salt stratified regulation irrigation device for rice-wheat intercropping in saline-alkali land according to claims 2 and 3, characterized in that: The output of the PLC controller (5) is electrically connected to the surface control valve (74), the deep control valve (75), the pump body (77), the fully automatic backwash control system (763), and multiple data transmission modules (892), respectively. The output of the solar panel (6) is electrically connected to the battery pack inside the PLC controller (5) through the charging controller.

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