Automatic sampling system for leaching solutions at different soil depths in farmland

Abstract

The present invention proposes an automatic sampling system for leaching solutions at different soil depths in farmland, comprising a soil leaching solution sampling unit, a soil leaching solution delivery unit, and a soil leaching solution sampling controller. The soil leaching solution sampling unit and the soil leaching solution delivery unit are both connected to the soil leaching solution sampling controller, and the soil leaching solution sampling unit is connected to the soil leaching solution delivery unit. The soil leaching solution sampling controller monitors the soil moisture content of the leaching solution sampling unit in real time, automatically activates the automatic sampling system for leaching solutions at different soil depths under set soil moisture parameters, delivers the soil leaching solution to a designated location via the soil leaching solution delivery unit, and monitors the chemical composition of the soil leaching solution in real time. The present invention can automatically extract leaching solutions from different soil profiles in real time based on soil moisture content, and automatically completes leaching solution sampling and delivery, laying the foundation for obtaining nitrate nitrogen, ammonium nitrogen, and other chemical components in leaching solutions at different soil depths.

Description

Technical Field

[0001] The invention relates to the technical field of soil leaching solution sampling, in particular to an automatic sampling system for leaching solutions at different soil depths in farmland. Background Art

[0002] According to incomplete statistics, 40% of fertilizer applied to the soil enters groundwater through soil leaching solutions during irrigation and heavy rain. Accurately assessing agricultural non-point source pollution requires accurate knowledge of the pollutant content in soil leaching solutions. Currently, regular soil leaching solution extraction and subsequent pollutant measurement are used to determine pollutant content, providing baseline data for the prevention and control of agricultural non-point source pollution. However, traditional soil leaching solution sampling methods either destroy the soil and alter its structure, or employ buried methods using suction cups and clay heads to obtain soil leaching solutions. This makes it difficult to accurately extract soil leaching solutions from different soil profiles, making it impossible to obtain accurate data on agricultural non-point source pollution, let alone the migration and transformation of pollutants under the influence of soil moisture, and thus, impossible to establish an accurate model of nitrogen migration and transformation in farmland soils. Summary of the Invention

[0003] In response to the technical problem that nitrate nitrogen and ammonium nitrogen cannot be accurately detected in real time in the study of soil nitrogen transformation and migration, the present invention proposes an automatic sampling system for leaching solutions at different soil depths in farmland. The system can be implanted below the soil tillage layer without affecting the mechanized tillage of farmland, and is suitable for long-term monitoring of changes in chemical elements in leaching solutions at different soil depths in farmland.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is implemented as follows: an automatic sampling system for leaching solutions at different soil depths in farmland, comprising a soil leaching solution sampling unit, a soil leaching solution delivery unit and a soil leaching solution sampling controller, wherein the soil leaching solution sampling unit and the soil leaching solution delivery unit are both connected to the soil leaching solution sampling controller, and the soil leaching solution sampling unit is connected to the soil leaching solution delivery unit; the soil leaching solution sampling controller monitors the soil moisture content collected by the leaching solution sampling unit in real time, automatically starts the soil leaching solution delivery units at different soil depths under the set soil moisture content parameters, and delivers the soil leaching solution to a designated location through the soil leaching solution delivery unit to monitor the content of specific chemical elements in the soil leaching solution in real time.

[0005] Preferably, the soil leaching solution sampling controller is connected to the sampling well environmental adjustment unit, and the sampling well environmental adjustment unit is arranged in the sampling well. The soil leaching solution sampling controller monitors the air temperature and humidity signals of the sampling well where the sampling well environmental adjustment unit is located in real time through the sampling well environmental adjustment unit, starts the fresh air unit in time, updates the humid air in the sampling well with external dry air, and adjusts the temperature and humidity parameters in the sampling well; the soil leaching solution sampling controller monitors the water level signal of the sampling well where the sampling well environmental adjustment unit is located in real time through the sampling well environmental adjustment unit, automatically starts the submersible pump to drain water, and avoids flooding and damage to equipment in the well.

[0006] Preferably, the soil leachate sampling unit includes a leachate sampling probe, a leachate accumulator, a negative pressure generating device, a soil moisture sensor, a soil salinity sensor, a soil temperature sensor, a pipeline pressure sensor, a first leachate level sensor and a second leachate level sensor. The leachate sampling probe, the leachate accumulator, the soil moisture sensor, the soil salinity sensor and the soil temperature sensor are all arranged in the soil; the leachate accumulator is connected to the leachate sampling probe through a first connecting pipe, the first connecting pipe is provided with the second leachate level sensor, the leachate accumulator is provided with the first leachate level sensor, and the leachate sampling probe is provided with The second connecting pipe, the third connecting pipe and the fourth connecting pipe are provided on the leaching solution accumulator, the fourth connecting pipe is connected to the negative pressure generating device, and the fourth connecting pipe is provided with a pipeline pressure sensor. The leaching solution sampling probe, the negative pressure generating device, the soil moisture sensor, the soil salinity sensor, the soil temperature sensor, the pipeline pressure sensor, the first leaching solution level sensor and the second leaching solution level sensor are all connected to the soil leaching solution sampling controller; the second connecting pipe, the third connecting pipe and the fourth connecting pipe are all connected to the soil leaching solution sampling controller; the leaching solution accumulator is connected to the soil leaching solution conveying unit through the third connecting pipe.

[0007] Preferably, the leachate sampling probes are placed horizontally in layers at different depths in the soil.

[0008] Preferably, the soil leaching solution delivery unit includes a first delivery pipe, one end of the first delivery pipe is connected to the leaching solution accumulator of the soil leaching solution sampling unit through a third connecting pipe, and the first delivery pipe is provided with a soil leaching solution delivery pump and a soil leaching solution delivery solenoid valve, and the soil leaching solution delivery pump and the soil leaching solution delivery solenoid valve are both connected to the soil leaching solution sampling controller.

[0009] Preferably, the other end of the first delivery pipe is connected to a container containing cleaning liquid, a forward and reverse rotating motor is provided in the soil leaching solution delivery pump, and the soil leaching solution delivery solenoid valve is connected to the waste liquid barrel through the second delivery pipe.

[0010] Preferably, the soil leaching solution sampling controller includes a control circuit board and a driving circuit board, and the control circuit board is respectively connected to the driving circuit board and the leaching solution sampling probe, negative pressure generating device, soil moisture sensor, soil salinity sensor, soil temperature sensor, pipeline pressure sensor, first leaching solution level sensor and second leaching solution level sensor of the soil leaching solution sampling unit; the second connecting pipe is provided with a first solenoid valve, the second connecting pipe is connected to the positive pressure pump, the third connecting pipe is provided with a second solenoid valve, and the fourth connecting pipe is provided with a third solenoid valve, the positive pressure pump, the first solenoid valve, the second solenoid valve, the third solenoid valve, the soil leaching solution delivery pump and the soil leaching solution delivery solenoid valve of the soil leaching solution delivery unit, and the negative pressure generating device are all connected to the driving circuit board.

[0011] Preferably, a liquid level sensor is provided on the rear side of the soil leaching solution delivery pump of the first delivery pipeline, and the liquid level sensor is connected to the control circuit board.

[0012] Preferably, the sampling well environmental conditioning unit includes an air temperature and humidity sensor, a fresh air duct, a cable pipe, a liquid level gauge and a submersible pump. The fresh air duct connects the fresh air at the bottom of the sampling well and the ground. The liquid level gauge is arranged at the bottom of the sampling well and is used to monitor the water level signal of the sampling well in real time. The submersible pump is arranged below the liquid level of the sampling well. The air temperature and humidity sensor and the liquid level gauge are connected to the control circuit board of the soil leaching solution sampling controller through the cable pipe, and the submersible pump is connected to the drive circuit board of the soil leaching solution sampling controller.

[0013] Compared with the prior art, the present invention has the following beneficial effects: since the soil leaching solution sampling units are placed at different soil depths without changing the soil structure, the soil leaching solution sampling units automatically complete soil leaching solution sampling at different depths according to information such as soil moisture content under the action of the soil leaching solution sampling controller, thereby providing technical support for effectively monitoring the changing patterns of pollutants in the original soil at different depths during transfer, improving the monitoring accuracy of agricultural non-point source pollution in farmland soil, and having important significance for the risk assessment of agricultural non-point source pollution.

[0014] The present invention can automatically extract leaching solutions from different soil profiles in real time based on soil moisture content. The soil leaching solution sampling controller automatically completes leaching solution sampling and transportation, laying the foundation for obtaining nitrate nitrogen, ammonium nitrogen, and other chemical components in leaching solutions at different soil depths. The present invention is fully automated, operates automatically, and significantly reduces manual sampling costs. It also solves the problem of real-time nitrate nitrogen and ammonium nitrogen detection in soil nitrogen transformation and migration studies, improves the output accuracy of farmland non-point source pollution models, and provides accurate data support for the prevention and control of agricultural non-point source pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a principle block diagram of the present invention.

[0017] Figure 2 for Figure 1 The principle block diagram of the soil leachate sampling unit is shown.

[0018] Figure 3 for Figure 1 The principle block diagram of the soil leaching solution delivery unit shown

[0019] Figure 4 for Figure 1 The principle block diagram of the soil leaching solution sampling controller is shown in the figure

[0020] Figure 5 for Figure 1 The functional block diagram of the sampling well environmental conditioning unit is shown.

[0021] In the figure, 1 is a soil leaching solution sampling unit, 11 is a leaching solution sampling probe, 12 is a leaching solution accumulator, 13 is a negative pressure generating device, 14 is a soil moisture sensor, 15 is a soil salinity sensor, 16 is a soil temperature sensor, 17 is a pipeline pressure sensor, 18 is a first leaching solution level sensor, 19 is a second leaching solution level sensor, 111 is a first connecting pipeline, 112 is a second connecting pipeline, 113 is a third connecting pipeline, 114 is a fourth connecting pipeline, 2 is a soil leaching solution delivery unit, 21 is a soil The leaching solution delivery pump, 22 is the soil leaching solution delivery solenoid valve, 23 is the waste liquid barrel, 211 is the first delivery pipeline, 212, 221, and 223 are all leaching solution delivery pipelines, 3 is the soil leaching solution sampling controller, 31 is the control circuit board, 32 is the drive circuit board, 33 is the positive pressure pump, 34 is the first solenoid valve, 35 is the second solenoid valve, 36 is the third solenoid valve, 4 is the sampling well environment adjustment unit, 41 is the air temperature and humidity sensor, 42 is the fresh air pipeline, 43 is the cable pipeline, 44 is the liquid level meter, and 45 is the submersible pump. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, an automatic sampling system for leachate at different soil depths in farmland includes a soil leachate sampling unit 1, a soil leachate delivery unit 2, and a soil leachate sampling controller 3. Both the soil leachate sampling unit 1 and the soil leachate delivery unit 2 are connected to the soil leachate sampling controller 3, and the soil leachate sampling unit 1 is connected to the soil leachate delivery unit 2. The soil leachate sampling unit is located below 30 cm in the cultivated layer of the farmland, without affecting large-scale mechanized agricultural tillage. The soil leachate sampling controller 3 monitors the soil moisture content collected by the leachate sampling unit 1 in real time, automatically activates the soil leachate sampling unit under set soil moisture parameters, and delivers the soil leachate to a designated location for testing via the soil leachate delivery unit 2 to monitor the content of specific chemical elements in the soil leachate in real time. Multiple soil leachate sampling units 1 and soil leachate delivery units 2 can be provided.

[0024] The soil leaching solution sampling controller 3 is connected to several sampling well environmental adjustment units 4, and the sampling well environmental adjustment units 4 are arranged in the sampling wells. The soil leaching solution sampling controller 3 monitors the air temperature and humidity signals of the sampling wells where the sampling well environmental adjustment units 4 are located in real time through the sampling well environmental adjustment units 4, starts the fresh air unit in time, updates the humid air in the sampling wells with external dry air, and adjusts the temperature and humidity parameters in the sampling wells; the soil leaching solution sampling controller 3 monitors the water level signals of the sampling wells where the sampling well environmental adjustment units 4 are located in real time through the sampling well environmental adjustment units 4, monitors the water level of the sampling wells where accidental liquid leakage due to rainfall and irrigation in real time, and automatically starts the submersible pump to drain water to avoid flooding and damage to equipment in the well. The sampling well environmental adjustment unit 4 can obtain the temperature, temperature and other gas information in the sampling well in real time, providing basic data to solve the problem of water accumulation in the sampling well due to liquid leakage, thereby corroding the sensors in the soil leaching solution sampling unit 1 and the electrical components of the soil leaching solution delivery unit 2, ensuring the continuous and stable operation of the automatic sampling system for leaching solutions at different soil depths in farmland.

[0025] like Figure 2As shown, the soil leachate sampling unit 1 includes a leachate sampling probe 11, a leachate accumulator 12, a negative pressure generating device 13, a soil moisture sensor 14, a soil salinity sensor 15, a soil temperature sensor 16, a pipeline pressure sensor 17, a first leachate level sensor 18 and a second leachate level sensor 19. The leachate sampling probe 11 is used to collect leachate from the soil, the leachate accumulator 12 is used to collect the leachate in the leachate sampling probe 11 and transport it to the soil leachate transport unit 2, the negative pressure generating device 13 is used to provide a negative pressure environment, the soil moisture sensor 14 is used to detect moisture in the soil, the soil salinity sensor 15 is used to detect salinity in the soil, the soil temperature sensor 16 is used to detect temperature in the soil, the pipeline pressure sensor 17 is used to detect pressure in the pipeline, the first leachate level sensor 18 is used to detect the liquid level of the leachate accumulator 12, and the second leachate level sensor 19 is used to detect the liquid level on the first connecting pipeline 111. The leachate sampling probe 11, the leachate accumulator 12, the soil moisture sensor 14, the soil salinity sensor 15 and the soil temperature sensor 16 are all arranged in the soil; the leachate accumulator 12 is connected to the leachate sampling probe 11 through a first connecting pipe 111, the first connecting pipe 111 is provided with a second leachate level sensor 19, the leachate accumulator 12 is provided with a first leachate level sensor 18, the leachate sampling probe 11 is provided with a second connecting pipe 112, the leachate accumulator 12 is provided with a third connecting pipe 113 and a fourth connecting pipe 114, the fourth connecting pipe 114 is connected to the negative pressure generating device 13, and the fourth connecting pipe 114 is provided with a pipe pressure sensor 17 The leachate sampling probe 11, the negative pressure generating device 13, the soil moisture sensor 14, the soil salinity sensor 15, the soil temperature sensor 16, the pipeline pressure sensor 17, the first leachate level sensor 18 and the second leachate level sensor 19 are all connected to the soil leachate sampling controller 3; the second connecting pipe 112, the third connecting pipe 113 and the fourth connecting pipe 114 are all connected to the soil leachate sampling controller 3, and the soil leachate sampling controller 3 is used to control whether the second connecting pipe 112, the third connecting pipe 113 and the fourth connecting pipe 114 are conductive; the leachate accumulator 12 is connected to the soil leachate delivery unit 2 through the third connecting pipe 113.

[0026] The soil leaching solution sampling unit 1 operates as follows: the soil leaching solution sampling controller 3 monitors the soil moisture signal collected by the soil moisture sensor 14 in real time. When the soil moisture content reaches a specified value (e.g., 30% by volume, set via software), the controller activates the negative pressure generating device 13, which provides a pressure differential for extracting the soil leaching solution. Simultaneously, the controller monitors the pressure value collected by the pipeline pressure sensor 17. Once the pressure value reaches a specified range (set via software within the controller 3), the controller deactivates the negative pressure generating device 13, completing a soil leaching solution sampling cycle. Data collected by the soil salinity sensor 15, soil temperature sensor 16, first leaching solution level sensor 18, and second leaching solution level sensor 19 are then transmitted to the soil leaching solution sampling controller 3. When the negative pressure value reaches a specified range (set via software within the controller 3), the controller connects the fourth connecting pipe 114, providing negative pressure. Under this negative pressure, the leaching solution sampling probe 11 draws leaching solution from the soil. The soil leachate sampling controller 3 monitors the second leachate level sensor 19 to determine whether the liquid has reached the designated position in the first connecting pipe 111, confirming that the leachate liquid has been extracted. The leachate enters the leachate accumulator 12, and the soil leachate sampling controller 3 monitors the signal changes from the first leachate level sensor 18 to calculate the amount of soil leachate collected (using software within the soil leachate sampling controller 3). When the volume reaches a designated value (configured within the software within the soil leachate sampling controller 3), the first connecting pipe 114 is switched to a zero pressure state (consistent pressure within the pipe, i.e., zero pressure differential). The leachate sampling probe 11 is depressurized, and no further soil solution is extracted. The soil leachate sampling controller 3 then switches the second connecting pipe 112 to a positive pressure state, pushing all the solution in the first connecting pipe 111 into the leachate accumulator 12. The soil leachate sampling controller 3 then disconnects the second connecting pipe 112.

[0027] Furthermore, the leachate sampling probes 11 are placed horizontally in layers at different depths of the soil, which is suitable for sampling leachate with a small volume under low soil moisture content and when long-distance transmission is required.

[0028] like Figure 3As shown, the soil leaching solution delivery unit 2 includes a first delivery pipe 211, one end of which is connected to the leaching solution accumulator 12 of the soil leaching solution sampling unit 1 via a third connecting pipe 113. A soil leaching solution delivery pump 21 and a soil leaching solution delivery solenoid valve 22 are sequentially provided on the first delivery pipe 211. Both the soil leaching solution delivery pump 21 and the soil leaching solution delivery solenoid valve 22 are connected to the soil leaching solution sampling controller 3. The soil leaching solution delivery pump 21 controls whether the first delivery pipe 211 delivers leaching solution, while the soil leaching solution delivery solenoid valve 22 controls whether the first delivery pipe 211 is connected. A leaching solution connecting pipe I 212 is provided between the soil leaching solution delivery pump 21 and the soil leaching solution delivery solenoid valve 22, and a leaching solution connecting pipe II 221 is provided between the soil leaching solution delivery solenoid valve 22 and a designated location.

[0029] Furthermore, the other end of the first delivery pipe 211 is connected to a container containing cleaning liquid. A forward and reverse motor is provided within the soil leaching solution delivery pump 21. The soil leaching solution delivery solenoid valve 22 is connected to a waste liquid tank 23 via a second delivery pipe 223. The leaching solution delivery solenoid valve 22 is a three-way valve that controls the connection between the leaching solution connection pipe I 212, the leaching solution connection pipe II 221, and the second delivery pipe 223.

[0030] The working process of the soil leaching solution delivery unit 2 is as follows: the soil leaching solution sampling controller 3 drives the soil leaching solution delivery solenoid valve 22 to connect the leaching solution connecting pipe II 212 and the first delivery pipe 221; the soil leaching solution sampling controller 3 connects the third connecting pipe 113 and the first delivery pipe 211, and then starts the soil leaching solution delivery pump 21 to extract the leaching solution from the leaching solution accumulator 12 and deliver it to the designated location through the leaching solution connecting pipe II 221, thereby performing leaching solution testing.

[0031] After the leachate solution is delivered, in order to avoid the influence of the residual liquid film on the pipe wall on the delivery of other samples, the soil leachate solution delivery pump 21 is reversed, and a certain amount of cleaning liquid (distilled water or deionized water) is extracted from the far end and injected into the leachate solution accumulator 12 to clean the leachate solution delivery pipeline and the leachate solution accumulator 12; then, the soil leachate solution sampling controller 3 drives the leachate solution delivery solenoid valve 22, connects the leachate solution connecting pipeline II 212 and the second delivery pipeline 223, and the soil leachate solution delivery pump 21 rotates forward to inject the cleaning liquid into the waste liquid bucket 23 through the second delivery pipeline 223.

[0032] like Figure 4As shown, the soil leaching solution sampling controller 3 includes a control circuit board 31 and a driver circuit board 32. The control circuit board 31 is used to collect sensor measurement data and send control instructions to the driver circuit board 32 based on the measured data. The driver circuit board 32 is used to activate and deactivate the actuator components, namely the solenoid valve and the pump. The control circuit board 31 is connected to the driver circuit board 32, as well as the leaching solution sampling probe 11, negative pressure generating device 13, soil moisture sensor 14, soil salinity sensor 15, soil temperature sensor 16, pipeline pressure sensor 17, first leaching solution level sensor 18, and second leaching solution level sensor 19 of the soil leaching solution sampling unit 1. A first solenoid valve 34 is provided in the second connecting pipeline 112 to control whether the second connecting pipeline 112 is open. The second connecting pipeline 112 is connected to a positive pressure pump 33, which provides positive pressure for the second connecting pipeline 112. A second solenoid valve 35 is provided in the third connecting pipeline 113 to control whether the third connecting pipeline 113 is open. A third solenoid valve 36 is installed in the fourth connecting pipe 114 to control the flow of the fourth connecting pipe 114. The positive pressure pump 33, the first solenoid valve 34, the second solenoid valve 35, the third solenoid valve 36, the soil leaching solution delivery pump 21 and the soil leaching solution delivery solenoid valve 22 of the soil leaching solution delivery unit 2, and the negative pressure generating device 13 are all connected to the driver circuit board 32. The third solenoid valve 36 is a three-way solenoid valve (one end is connected to the leaching solution sampling probe 11, one end is connected to the negative pressure pipe, and the other end is connected to the soil leaching solution delivery pipe). The first solenoid valve 34 and the second solenoid valve 35 are two-way solenoid valves.

[0033] Furthermore, a liquid level sensor 37 is provided at the rear side of the soil leaching solution delivery pump 21 of the first delivery pipeline 211 , and the liquid level sensor 37 is connected to the control circuit board 31 . The liquid level sensor 37 is used to detect the liquid level of the first delivery pipeline 211 .

[0034] The soil leachate sampling controller 3 operates as follows: the control circuit board 31 receives the soil moisture signal from the soil moisture sensor 14 and activates the negative pressure generating device 13 via the driver circuit board 32, generating a pressure differential. The control circuit board 31 then receives the pressure signal from the pipeline pressure sensor 17 and activates the third solenoid valve 36 via the driver circuit board 32, connecting the fourth connecting pipeline 114 and beginning negative pressure pumping of the soil leachate into the leachate accumulator 12. After sufficient leachate has been collected, the third solenoid valve 36 closes, depressurizing the fourth connecting pipeline 114 and ceasing pumping of the soil leachate into the leachate accumulator 12. The control circuit board 31 activates the first solenoid valve 34 via the driver circuit board 32, connecting the second connecting pipeline 112 to the positive pressure pump 33. The control circuit board 31 activates the positive pressure pump 33 via the driver circuit board 32, pushing all the soil solution in the first connecting pipeline 111 into the leachate accumulator 12. The positive pressure pump 33 and the first solenoid valve 34 are then closed. The control circuit board 31 activates the second solenoid valve 35 through the drive circuit board 32, connects the third connecting pipe 113, connects the soil leachate solution delivery pump 21, and delivers the leachate solution from the leachate solution accumulator 12; the liquid level sensor 37 monitors the liquid flow in the leachate solution connecting pipe II 212. The control circuit board 31 uses the liquid level sensor 37 to indirectly determine whether the leachate solution accumulator 12 is empty, providing a decision basis for stopping solution delivery.

[0035] like Figure 5 As shown, the sampling well environmental conditioning unit 4 includes an air temperature and humidity sensor 41, a fresh air duct 42, a cable conduit 43, a liquid level gauge 44, and a submersible pump 45. The air temperature and humidity sensor 41 is located in the sampling well to measure the temperature and humidity of the air in the sampling well. The cable conduit 43 is located between the sampling well and the sampling controller, transmitting electrical parameter signals (including air temperature and humidity, soil moisture, salinity, temperature, and pipeline pressure) from the sampling well environmental conditioning unit 4 and the sampling probe to the sampling controller. The fresh air duct 42 connects the bottom of the sampling well with the fresh air at the ground level. The liquid level gauge 44 is located at the bottom of the sampling well to monitor the water level in the sampling well in real time. The submersible pump 45 is located below the liquid level in the sampling well. The air temperature and humidity sensor 41 and the liquid level gauge 44 are connected to the control circuit board 31 of the soil leaching solution sampling controller 3 via the cable conduit 43. The submersible pump 45 is connected to the driver circuit board 32 of the soil leaching solution sampling controller 3.

[0036] The sampling well environmental conditioning unit 4 operates as follows: The soil leachate sampling controller 3 monitors the temperature and humidity signals from the air temperature and humidity sensor 41 in real time. If the temperature and humidity exceed the set range, fresh air from the ground (driven by a fresh air blower) is injected into the bottom of the sampling well via the fresh air duct 42 and then returned to the ground via the cable duct 43. This flowing air regulates the temperature and humidity within the enclosed space of the sampling well. The soil leachate sampling controller 3 also monitors the water level signal from the liquid level gauge 44 in real time and activates the submersible pump 45 when appropriate to drain the accumulated water to the ground.

[0037] The present invention comprises a soil leaching solution sampling unit, a soil leaching solution delivery unit, and a soil leaching solution sampling controller. The soil leaching solution sampling unit can be placed at different soil depths without changing the soil structure. The soil leaching solution sampling unit includes a soil leaching solution sampling probe, a soil moisture sensor, a soil salinity sensor, and a soil temperature sensor. Under the control of the soil leaching solution sampling controller, the soil leaching solution sampling unit automatically completes different soil leaching solution samplings according to the soil moisture content, thereby effectively monitoring the changes in the transfer process of pollutants in the original soil at different depths, improving the monitoring accuracy of agricultural non-point source pollution in farmland soil, and having important significance for the risk assessment of agricultural non-point source pollution.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An automatic sampling system for leaching solutions at different soil depths in farmland, characterized in that: The invention comprises a soil leaching solution sampling unit (1), a soil leaching solution delivery unit (2) and a soil leaching solution sampling controller (3), wherein the soil leaching solution sampling unit (1) and the soil leaching solution delivery unit (2) are both connected to the soil leaching solution sampling controller (3), and the soil leaching solution sampling unit (1) is connected to the soil leaching solution delivery unit (2); the soil leaching solution sampling controller (3) monitors the soil moisture content collected by the leaching solution sampling unit (1) in real time, automatically starts the soil leaching solution delivery units (2) at different soil depths under the set soil moisture content parameter, and delivers the soil leaching solution to a designated location through the soil leaching solution delivery unit (2), so as to monitor the content of specific chemical elements in the soil leaching solution in real time; The soil leachate sampling unit (1) comprises a leachate sampling probe (11), a leachate accumulator (12), a negative pressure generating device (13), a soil moisture sensor (14), a soil salinity sensor (15), a soil temperature sensor (16), a pipeline pressure sensor (17), a first leachate level sensor (18), and a second leachate level sensor (19). The leachate sampling probe (11), the leachate accumulator (12), the soil moisture sensor (14), the soil salinity sensor (15), and the soil temperature sensor (16) are all arranged in the soil. The leachate accumulator (12) is connected to the leachate sampling probe (11) via a first connecting pipe (111). The first connecting pipe (111) is provided with the second leachate level sensor (19). The leachate accumulator (12) is provided with the first leachate level sensor (18). The leachate sampling probe (11) is provided with the second connecting pipe ( 112), a third connecting pipe (113) and a fourth connecting pipe (114) are provided on the leachate accumulator (12), the fourth connecting pipe (114) is connected to the negative pressure generating device (13), and a pipe pressure sensor (17) is provided on the fourth connecting pipe (114). The leachate sampling probe (11), the negative pressure generating device (13), the soil moisture sensor (14), the soil salinity sensor (15), the soil temperature sensor (16), the pipe pressure sensor (17), the first leachate level sensor (18) and the second leachate level sensor (19) are all connected to the soil leachate sampling controller (3); the second connecting pipe (112), the third connecting pipe (113) and the fourth connecting pipe (114) are all connected to the soil leachate sampling controller (3); the leachate accumulator (12) is connected to the soil leachate delivery unit (2) via the third connecting pipe (113).

2. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 1 is characterized in that: The soil leaching solution sampling controller (3) is connected to the sampling well environment regulating unit (4), and the sampling well environment regulating unit (4) is arranged in the sampling well. The soil leaching solution sampling controller (3) monitors the air temperature and humidity signals of the sampling well where the sampling well environment regulating unit (4) is located in real time through the sampling well environment regulating unit (4), starts the fresh air unit in a timely manner, updates the humid air in the sampling well with external dry air, and adjusts the temperature and humidity parameters in the sampling well; the soil leaching solution sampling controller (3) monitors the water level signal of the sampling well where the sampling well environment regulating unit (4) is located in real time through the sampling well environment regulating unit (4), and automatically starts the submersible pump to drain water, thereby preventing the equipment in the well from being flooded and damaged.

3. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 1 is characterized in that: The leachate sampling probes (11) are placed horizontally in layers at different depths in the soil.

4. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 1 is characterized in that: The soil leaching solution delivery unit (2) comprises a first delivery pipe (211), one end of which is connected to the leaching solution accumulator (12) of the soil leaching solution sampling unit (1) via a third connecting pipe (113), and a soil leaching solution delivery pump (21) and a soil leaching solution delivery electromagnetic valve (22) are provided on the first delivery pipe (211), and both the soil leaching solution delivery pump (21) and the soil leaching solution delivery electromagnetic valve (22) are connected to the soil leaching solution sampling controller (3).

5. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 4 is characterized in that: The other end of the first delivery pipe (211) is connected to a container containing cleaning liquid. A forward and reverse rotating motor is provided in the soil leaching solution delivery pump (21). The soil leaching solution delivery solenoid valve (22) is connected to the waste liquid barrel (23) via the second delivery pipe (223).

6. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 4 or 5, characterized in that: The soil leaching solution sampling controller (3) comprises a control circuit board (31) and a drive circuit board (32), wherein the control circuit board (31) is respectively connected to the drive circuit board (32) and the leaching solution sampling probe (11), the negative pressure generating device (13), the soil moisture sensor (14), the soil salinity sensor (15), the soil temperature sensor (16), the pipeline pressure sensor (17), the first leaching solution level sensor (18), and the second leaching solution level sensor (19) of the soil leaching solution sampling unit (1); the second connecting pipe (112) is connected to the first leaching solution level sensor (18) and the second leaching solution level sensor (19). A first solenoid valve (34) is provided, a second connecting pipe (112) is connected to a positive pressure pump (33), a second solenoid valve (35) is provided on the third connecting pipe (113), a third solenoid valve (36) is provided on the fourth connecting pipe (114), and the positive pressure pump (33), the first solenoid valve (34), the second solenoid valve (35), the third solenoid valve (36), the soil leaching solution delivery pump (21) and the soil leaching solution delivery solenoid valve (22) of the soil leaching solution delivery unit (2), and the negative pressure generating device (13) are all connected to the driving circuit board (32).

7. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 6 is characterized in that: A liquid level sensor (37) is provided on the rear side of the soil leaching solution delivery pump (21) of the first delivery pipeline (211), and the liquid level sensor (37) is connected to the control circuit board (31).

8. The automatic sampling system for leaching solution at different soil depths in farmland according to claim 2, characterized in that: The sampling well environment conditioning unit (4) comprises an air temperature and humidity sensor (41), a fresh air duct (42), a cable duct (43), a liquid level meter (44) and a submersible pump (45). The fresh air duct (42) connects the fresh air at the bottom of the sampling well with the ground. The liquid level meter (44) is arranged at the bottom of the sampling well and is used to monitor the liquid level signal of the water in the sampling well in real time. The submersible pump (45) is arranged below the liquid level of the sampling well. The air temperature and humidity sensor (41) and the liquid level meter (44) are connected to the control circuit board (31) of the soil leaching solution sampling controller (3) through the cable duct (43). The submersible pump (45) is connected to the drive circuit board (32) of the soil leaching solution sampling controller (3).

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