Saline-alkali soil improvement condition detection device and method

Abstract

The invention relates to the technical field of soil detection, and provides a saline-alkali soil improvement condition detection device and method, and the device comprises a protection and guide assembly, a water content detector and a detachable soil component detection system. The protection and guide assembly is internally provided with a guide rail and is placed in a soil pit of a to-be-detected point; the water content detector realizes water content detection of a soil profile through array probe distribution; the soil component detection system is used for carrying out layered detection on soil with the depth of 5-100cm by driving a lifter through a servo motor. After laser is focused on a detection surface to generate plasma, a spectrograph collects an atomic emission spectrum, a matrix effect compensation model is established in combination with the water content, a characteristic spectral line is corrected, detection of soil elements and salt thereof at different depths is achieved through a built-in component quantitative analysis algorithm, and the defects that traditional sampling is large in workload and high in sampling precision are overcome. The modular structure of the soil salinization monitoring device is convenient to disassemble, assemble and maintain in the field, and supports are provided for long-term monitoring and treatment of soil salinization.

Description

Technical Field

[0001] The present invention relates to the technical field of soil detection, and particularly to a detection device and method for the improvement status of saline-alkali land. Background Art

[0002] Saline-alkali land refers to land where the soil salt content affects crop growth. The salts accumulated in saline-alkali soil not only affect the normal growth and development of crops, but also lead to the deterioration of soil structure and the decline of productivity, posing a serious threat to agricultural production and the ecological environment. Due to the dynamic migration characteristics of salts in the soil profile, traditional detection methods relying on surface samples are difficult to accurately reflect the spatial heterogeneity of salts. Therefore, it is crucial to timely and accurately monitor the soil salt and element composition at different depths for formulating effective saline-alkali land improvement measures.

[0003] The existing salt monitoring technology system faces multiple technical bottlenecks: The traditional profile sampling method relies on manual excavation of test pits for stratified sampling, and its destructiveness lies in: (1) The sampling process irreversibly damages the original pore structure of the soil, resulting in the loss of long-term observation value of the monitoring point; (2) The capillary fracture and solution redistribution during the excavation of different soil layers cause secondary migration pollution of salts between layers.

[0004] In detection technologies, methods such as the conductivity method (EC) and colorimetric method, although having high detection efficiency, are difficult to obtain multi-element quantitative data. Although laboratory analysis can use technologies such as ICP-OES and XRF to determine the total element composition, it has limitations such as sample pretreatment, long detection cycle, high detection cost, and limited field operations, which restrict the in-situ detection and real-time tracking of key processes such as seasonal salt return and irrigation leaching.

[0005] Therefore, in order to realize the detection of the status of saline-alkali land in terms of depth and breadth, it is particularly important to develop a detection device that can quickly, accurately, and at low cost detect different depths of soil in the field environment and can be quickly deployed for the targeted improvement of saline-alkali land. Summary of the Invention

[0006] The present invention provides a detection device and method for the improvement status of saline-alkali land, realizing the detection of the status of saline-alkali land in terms of depth and breadth, so as to solve the defects in the prior art that the detection device cannot meet the targeted improvement of large areas of saline-alkali land, and has low detection efficiency and high cost. In addition, the detection method using this device can reduce the influence caused by the soil matrix effect in detection and improve the detection accuracy of soil salinization in the vertical depth.

[0007] The present invention provides a detection device for the improvement status of saline-alkali land, comprising: A protection and guiding component, which is placed in the soil deep pit at the point to be detected; Multiple moisture content detectors are installed on the outer sidewall of the protection and guiding assembly for detecting the moisture content of the soil at different depths of the point to be detected; A soil composition detection system is detachably connected to the protection and guiding assembly, which is used to emit laser to generate plasma in the soil at different depths of the point to be detected, measure the atomic emission spectrum, and detect the composition of the soil at different depths based on the atomic emission spectrum and the moisture content; A control system is respectively connected to the protection and guiding assembly, the soil composition detection system, and the moisture content detector, and is used to control the protection and guiding assembly to drive the soil composition detection system to move in the vertical direction of the ground. The control system is also used to receive the measurement data of the moisture content detector.

[0008] According to the saline-alkali land improvement condition detection device provided by the present invention, the protection and guiding assembly includes: A guide rail, on which the soil composition detection system is installed, and the control system controls the up and down movement of the guide rail; Detection windows corresponding to different depths respectively. When the soil composition detection system reaches the current depth, the control system controls the current detection window to open for detecting the composition of the soil at the current depth, and closes the current detection window after the detection is completed.

[0009] According to the saline-alkali land improvement condition detection device provided by the present invention, the protection and guiding assembly includes a protection shell and a waterproof coating, and further includes: A baffle plate installed on the top of the protection and guiding assembly; A protective cover and a waterproof cover installed outside the detection window; A base connected to the guide rail for fixing the guide rail.

[0010] According to the saline-alkali land improvement condition detection device provided by the present invention, the soil composition detection system includes: A laser for emitting pulsed laser to the soil at different depths to form laser plasma; A spectrometer for receiving the atomic emission spectrum emitted by the laser plasma; An optical path module for processing the optical paths of the laser and the spectrometer; A three-dimensional moving platform for carrying the laser, the spectrometer and the optical path module; A spectral data processing module for detecting the composition of the soil at different depths based on the atomic emission spectrum and the moisture content.

[0011] According to the saline-alkali land improvement condition detection device provided by the present invention, the spectral data processing module includes: A spectral line screening unit, configured to screen spectral lines of the atomic emission spectra of the soils at different depths based on the wavelengths of elements related to soil salinity, so as to obtain the measured spectral intensity of the element to be measured in the atomic emission spectra; A spectral correction unit, configured to correct the measured spectral intensity based on the water content of the soil corresponding to the depth of the atomic emission spectra, so as to obtain the corrected spectral intensity of the related element; A component detection unit, configured to perform component detection on the soils at different depths based on the corrected spectral intensity of the related element.

[0012] According to the saline-alkali land improvement condition detection device provided by the present invention, the spectral correction unit is specifically configured to: Correct the measured spectral intensity based on the following formula: ; where is the finally corrected spectral intensity, is the measured spectral intensity, is the exponential decay factor, is a constant representing the influence of moisture on spectral intensity, is the water content of the soil, is the water content of the soil corresponding to the measured spectral intensity , are polynomial coefficients reflecting the non-linear influence of water content on spectral intensity.

[0013] According to the saline-alkali land improvement condition detection device provided by the present invention, the component detection unit includes an element content detection sub-unit, configured to: Obtain the standard spectral intensity of different elements in a standard soil sample based on laser-induced breakdown spectroscopy; Fit the element content of different elements with the standard spectral intensity to obtain standard curves of different elements; Match the corrected spectral intensity of the related element with the standard curves of different elements, and obtain the element content of the soils at different depths based on the matching result.

[0014] According to the saline-alkali land improvement condition detection device provided by the present invention, the component detection unit includes a water-soluble total salt content detection sub-unit, configured to: Detect the water-soluble total salt content of the soils at different depths based on the corrected spectral intensity and a trained water-soluble total salt content detection model, where the water-soluble total salt content detection model is trained based on sample spectral intensity and its corresponding water-soluble total salt content label.

[0015] According to the saline-alkali land improvement condition detection device provided by the present invention, the spectral data processing module further includes a preprocessing unit for: Before screening the spectral lines of the atomic emission spectra of the soils at different depths, preprocess the atomic emission spectra of the soils at different depths; The preprocessing includes background removal of the atomic emission spectra based on wavelet transform background subtraction, elimination of abnormal spectra, and averaging of the spectral intensities of consecutive multiple atomic emission spectra.

[0016] The present invention also provides a detection method, which is applied to the saline-alkali land improvement condition detection device, and the method includes: Obtain the water contents of the soils at different depths of the point to be detected through multiple water content detectors, where the multiple water content detectors are installed on the outer side wall of the protection and guiding component, and the protection and guiding component is placed in the soil deep pit of the point to be detected; Control the protection and guiding component to drive the soil component detection system to move in the vertical direction on the ground; The soil component detection system emits laser to the soils at different depths of the point to be detected to generate plasma, measures the atomic emission spectra, corrects the atomic emission spectra based on the water content, and performs component detection on the soils at different depths based on the corrected atomic emission spectra.

[0017] The saline-alkali land improvement condition detection device and method provided by the present invention provide soil component detection conditions at different depths through the protection and guiding component. The soil component detection system is detachably connected to the protection and guiding component. Each time detection is performed, only the soil component detection system needs to be fixed on the protection and guiding component to achieve rapid detection of the element changes and physical and chemical quantities in soil salinization. This device is suitable for detecting the improvement conditions of saline-alkali land in field operation at the front line, and can improve the detection efficiency and reduce the detection cost.

[0018] In addition, by detecting the water contents of the soils at different depths of the point to be detected, the water condition of the soil can be accurately grasped, the dynamic change of the soil water can be understood, and the corresponding relationship between the water content and the salt content of the soil can be known, providing a scientific basis for formulating a comprehensive improvement plan. At the same time, component detection of the soils at different depths based on the atomic emission spectra and the water content can take into account the influence of the water content on the atomic emission spectra, reduce the influence caused by the soil matrix effect in detection, and thus improve the detection accuracy of soil salinization in the vertical direction. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is one of the structural schematic diagrams of the saline-alkali land improvement condition detection device provided by the present invention.

[0021] Figure 2 It is the second structural schematic diagram of the saline-alkali land improvement condition detection device provided by the present invention.

[0022] Figure 3 It is one of the structural schematic diagrams of the soil component detection system provided by the present invention.

[0023] Figure 4 It is the second structural schematic diagram of the soil component detection system provided by the present invention.

[0024] Figure 5 It is the structural schematic diagram of the control system provided by the present invention.

[0025] Figure 6 It is the flow schematic diagram of the detection method provided by the present invention.

[0026] Figure 7 It is the schematic diagram of the experimental verification results provided by the present invention.

[0027] Reference numerals: 110: Protection and guiding component; 120: Soil component detection system; 130: Water content detector; 140: Control system; 141: Control center; 142: Component detection system center; 143: Water detection system center; 144: Detection window switch; 145: Power supply; 146: Motor; 111: Guide rail; 112: Detection window; 113: Protection shell; 114: Waterproof coating; 115: Baffle; 116: Protective cover; 117: Waterproof cover; 118: Base; 119: Fixed buckle; 121: Laser; 122: Spectrometer; 123: Optical path module; 1231: Reflecting mirror; 1232: Dichroic mirror; 1233: Main mirror; 1234: Focusing lens; 124: Three-dimensional moving platform; 125: Spectral data processing module; 126: Control screen; 127: Built-in computer; 128: Handle; 129: USB interface; 150: Ground; 160: Topsoil layer; 170: Subsoil layer. Detailed implementation manners

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0029] In view of the problems in the prior art that the detection method cannot meet the targeted improvement of saline-alkali land, and the detection efficiency is low, the cost is high, and the detection accuracy is not high, an embodiment of the present invention proposes a detection device for the improvement status of saline-alkali land. Figure 1 It is one of the structural schematic diagrams of the detection device for the improvement status of saline-alkali land provided by the present invention. As Figure 1 shown, the device includes: A protection and guiding component 110, which is placed in the soil deep pit at the detection point.

[0030] A soil component detection system 120, which is detachably connected to the protection and guiding component, is used to emit laser to generate plasma in the soil at different depths of the detection point, measure the atomic emission spectrum, and perform component detection on the soil at different depths based on the atomic emission spectrum and water content.

[0031] A plurality of water content detectors 130, which are installed on the outer side wall of the protection and guiding component, are used to detect the water content of the soil at different depths of the detection point.

[0032] A control system 140, which is respectively connected to the protection and guiding component, the soil component detection system, and the water content detector, is used to control the protection and guiding component to drive the soil component detection system to move in the vertical direction on the ground. The control system is also used to receive the measurement data of the water content detector.

[0033] Specifically, the causes of soil salinization are complex and diverse, and the soil salts continuously move horizontally and vertically during the improvement process. Considering that there is little research on the influence of the vertical movement of soil salts on salinization in the related art, this embodiment detects the components of the soil at different depths of the detection point, aiming to deeply understand the distribution characteristics and dynamic change laws of soil salinization in the vertical direction, and provide a scientific basis for formulating precise and effective improvement measures.

[0034] At the same time, in order to adapt to field operation in the front line and complete soil component detection quickly and at low cost, the detection device for the improvement status of saline-alkali land provided by this embodiment includes a protection and guiding component, a soil component detection system, a plurality of water content detectors, and a control system.

[0035] Among them, the protection and guiding component can be, for example, a cylindrical structure, which is used to provide detection conditions for the soil component detection system. Different typical areas in the saline-alkali land are selected as the points to be detected, and circular deep pits with a radius of 0.4 meters and a depth of 1 meter are dug at each point to be detected. The protection and guiding component is placed in the deep pit and filled with soil at the edge part.

[0036] Figure 2 It is the second structural schematic diagram of the saline-alkali land improvement condition detection device provided by the present invention. As Figure 2 shown, the circular deep pit from top to bottom is the ground 150, the surface soil layer 160 and the subsoil layer 170 in sequence. The ground 150, the surface soil layer 160 and the subsoil layer 170 belong to soil layers at different depths.

[0037] Referring to Figure 2 , 0 in the figure represents the zero position of the X and Y coordinates, and R is the radius of the circular pit where the saline-alkali land improvement condition detection device is placed. 15 cm represents 15 cm above the ground, 0 cm represents the ground position, -20 cm represents 20 cm underground.

[0038] After the protection and guiding component is placed for 1-2 months, due to the water-salt movement of the soil, the soil outside the edge of the detection device gradually shows characteristics similar to those of the detection area. Driven by natural forces such as gravity, capillary action, and osmotic pressure, the water and salt in the soil will migrate in horizontal and vertical directions. Through long-term placement and observation, these natural processes can be verified and understood how they affect the distribution and change of soil salinity, so as to more deeply understand the dynamic mechanism of salinization.

[0039] At the same time, during this process, the water content of the soil at different depths of the detection point is detected in real time by a water content detector, and the detected water content data is stored. There can be multiple water content detectors, which are respectively installed at different depths on the outer side wall of the protection and guiding component.

[0040] After the protection and guiding component is placed in the deep pit for a period of time, the soil component detection system can be installed to detect the soil components. The soil component detection system is detachably connected to the protection and guiding component, for example, it can be connected by a buckle. The soil component detection system can move up and down in the space of the protection and guiding component, so as to detect the components of the soil at different depths.

[0041] The soil composition detection system obtains the atomic emission spectra of soils at different depths of the point to be detected through laser-induced breakdown spectroscopy, and detects the composition of soils at different depths based on the atomic emission spectra. The laser in the soil composition detection system emits laser to the soils at different depths to generate plasma, and the spectrometer receives the plasma and measures the atomic emission spectra. Both the water content and the atomic emission spectra correspond to the soils at different depths. By combining the water content to process the atomic emission spectra, the composition detection results of soils at different depths are obtained. Considering that the water content may affect the atomic emission spectra, the atomic emission spectra at a certain depth can be corrected based on the water content of the soil at that depth, so as to improve the detection accuracy of the soil at that depth.

[0042] Here, detecting the composition of soils at different depths can specifically be detecting the element categories, element contents, and water-soluble total salt contents of the soils.

[0043] The saline-alkali land improvement condition detection device further includes a control system, which is respectively connected to the protection and guiding component, the soil composition detection system, and the water content detector.

[0044] The control system includes a control center 141, which is used to issue motion instructions for the devices to be controlled (such as the protection and guiding component, the soil composition detection system, and the water content detector), as well as the transmission and processing of information. The control system also includes a composition detection system center 142, which is used to control the switch of the soil composition detection system. The control system also includes a water detection system center 143, which is used to receive information from the water content detector, convert it into the water content, and transmit it to the control center.

[0045] The saline-alkali land improvement condition detection device provided by the embodiment of the present invention can deeply understand the distribution characteristics and dynamic change laws of soil salinization in the vertical direction by detecting the composition of soils at different depths of the point to be detected, and provide a scientific basis for formulating accurate and effective improvement measures.

[0046] The saline-alkali land improvement condition detection device provides the detection conditions for the soil composition at different depths through the protection and guiding component. The soil composition detection system is detachably connected to the protection and guiding component. Each time of detection, only by fixing the soil composition detection system on the protection and guiding component, the rapid detection of the element changes and physical and chemical quantities in the soil salinization can be realized. This device is suitable for the detection of the improvement conditions of saline-alkali land in the field operation at the front line, and can improve the detection efficiency and reduce the detection cost.

[0047] In addition, by detecting the water content of soils at different depths at the point to be detected, the water condition of the soil can be accurately grasped, the dynamic changes of soil moisture can be understood, as well as the corresponding relationship between the water content and salinity of the soil, providing a scientific basis for formulating a comprehensive improvement plan. At the same time, by detecting the composition of soils at different depths based on atomic emission spectroscopy and water content, the detection accuracy of soil salinization in the vertical direction can be improved.

[0048] Based on any of the above embodiments, the protection and guiding component 110 specifically includes: A guide rail 111, on which the soil composition detection system is installed, and the control system controls the up and down movement of the guide rail; Detection windows 112 corresponding to different depths respectively. When the soil composition detection system reaches the current depth, the control system controls the current detection window to open for detecting the composition of the soil at the current depth, and closes the current detection window after the detection is completed. In order to detect the composition of the soil in the vertical direction, detection windows need to be set at different depths in the vertical direction.

[0049] Specifically, in order to realize the detection of the composition of soils at different depths, the vertical movement of the soil composition detection system can be achieved through the guide rail. The soil composition detection system is installed on the guide rail through a fixing buckle 119. The control system controls the up and down movement of the guide rail through a motor, thereby driving the up and down movement of the soil composition detection system.

[0050] The protection and guiding component further includes a plurality of detection windows, and the detection windows respectively correspond to different depths. Correspondingly, the control system further includes a detection window switch 144, which is used to receive the instruction from the control center, control the current detection window to open for detecting the composition of the soil at the current depth, and close the current detection window after the detection is completed. Rubber is used at the interface of the detection window to improve the interface sealing performance and prevent water from flowing into the interior of the device.

[0051] Preferably, the protection and guiding component includes a protection shell 113 and a waterproof coating 114. The protection shell prevents the internal detection environment from being affected by external forces (such as soil extrusion, animal activities, etc.). The waterproof coating is used to improve the overall waterproof performance of the device and prevent water from flowing into the interior of the device in all directions. The waterproof coating 114 belongs to the external structure part, and its main purpose is to prevent the water in the soil from seeping into the interior of the device and forming accumulated water when it is placed in the soil for a long time. The protection and guiding component further includes: A baffle 115, installed at the top of the protection and guiding component, used to protect the top of the device and prevent damage to the instrument itself due to weather reasons.

[0052] A protective cover 116 and a waterproof cover 117 installed outside the detection window. The protective cover protects the detection window and prevents damage to the detection window by external forces. The waterproof cover improves the sealing performance of the device and prevents the water in the soil from flowing into the interior of the device through the detection window.

[0053] The base 118 is connected to the guide rail and is used to fix the guide rail.

[0054] Figure 3 and Figure 4 is a schematic structural diagram of the soil component detection system provided by the present invention. As Figure 3 shown, the soil component detection system includes: A laser 121, which is used to emit pulsed laser to soils at different depths, so as to form laser plasma; A spectrometer 122, which is used to receive the atomic emission spectrum emitted by the laser plasma; An optical path module 123, which is used to process the optical paths of the laser and the spectrometer; A three-dimensional moving platform 124, which is used to carry the laser, the spectrometer and the optical path module, and control the laser, the spectrometer and the optical path module to move in the x, y, and z directions; A spectral data processing module 125, which is used to detect the components of soils at different depths based on the atomic emission spectrum.

[0055] Specifically, during the operation of the soil component detection system, the laser reflects the laser to the soil plane at the detection window to generate plasma; the spectrometer receives the atomic emission spectrum emitted by the plasma; through the spectral data processing module contained in the built-in computer, the components of soils at different depths are detected based on the atomic emission spectrum.

[0056] Furthermore, the soil component detection system further includes a control screen 126, which is used to display the state of the soil component detection system and control the entire system.

[0057] A built-in computer 127, which contains a spectral data processing module and is used for spectral data processing and controlling the laser and the spectrometer.

[0058] A handle 128, which is used to facilitate the carrying of the soil component detection system.

[0059] A USB interface 129, which is used for data transmission and keyboard and mouse interface (used when the control screen has poor contact).

[0060] Among them, the optical path module 123 specifically includes: a reflecting mirror 1231, which reflects the pulsed laser emitted by the laser; a dichroic mirror 1232, which is used to reflect the pulsed laser and allow the light emitted by the plasma to pass through; a main mirror 1233, which is used to focus the pulsed laser; a focusing lens 1234, which is used to converge the light emitted by the plasma.

[0061] When detecting this area, the soil component detection system is installed on the guide rail through its fixing buckle and connected to the control system. The schematic structural diagram of the control system is referred to Figure 5, first, turn on the power supply 145. The control center in the control system controls the motor to lift the soil component detection system. After the motor 146 reaches the specified depth, the motor stops moving. The control center issues an instruction to the detection window switch to sequentially open the waterproof cover and the protective cover of the detection window at this depth. After being fully opened, the control center transmits the instruction to the detection system center, and this center transmits the instruction to the soil component detection system.

[0062] After the soil component detection system receives the instruction, the laser generates pulsed laser with a wavelength of 1064 nm. After changing the path of the laser through the reflecting mirror and the dichroic mirror, it is focused on the soil plane at the edge of the device shell through the main mirror, thus forming a laser plasma. The atomic and ionic energy levels of different elements in the plasma continuously transition and emit light outward. This light passes through the main mirror and the dichroic mirror to reach the focusing lens, and is converged on the spectrometer through the focusing lens, thereby obtaining the atomic emission spectrum of the elements in the soil.

[0063] After completion, the three-dimensional moving platform moves in the Y-axis direction with a step size of 1 mm. After reaching the position, sampling is performed again. It moves a total of 10 mm in the y-axis direction, and then moves 1 mm in the z-axis direction, moving 10 times in total. And after each movement, it moves in the -y or y direction again. The step size of this movement process is 1 mm, thereby forming a detection range of 10 mm × 10 mm.

[0064] After the detection is completed, the soil component detection system feeds back to the detection system center, and the detection system center feeds back to the control center. The control center controls the motor to lift the soil component detection system again. After the motor reaches the specified depth, the motor stops moving. The control center issues an instruction to the detection window switch to sequentially open the waterproof cover and the protective cover of the detection window at this depth. After being fully opened, the control center transmits the instruction to the detection system center, and this center transmits the instruction to the soil component detection system, thereby completing the detection of the soil components at different depths at this point.

[0065] After obtaining the atomic emission spectra of the soil at different depths at this point, the control center controls the motor to lift the soil component detection system to the ground position, removes the soil component detection system, and connects the soil component detection system to the water content detector through the usb interface. Read the water content of the soil at different depths through the control screen and match it with the spectra at different depths. After completing the measurement at this point, install the soil component detection system at other points and continue the above operations.

[0066] Based on any of the above embodiments, the spectral data processing module includes: A spectral line screening unit for screening the spectral lines of the atomic emission spectra of the soil at different depths based on the wavelengths of the elements related to soil salinity to obtain the measured spectral intensity of the elements to be measured in the atomic emission spectrum; A spectral correction unit for correcting the measured spectral intensity based on the water content of the soil at the depth corresponding to the atomic emission spectrum to obtain the corrected spectral intensity of the relevant elements; A composition detection unit for detecting the composition of soils at different depths based on the corrected spectral intensity of the relevant elements.

[0067] Specifically, considering that the water content of the soil affects the spectral intensity, in order to further reduce the influence of the water content on the spectral intensity, the measured spectral intensity is corrected in this embodiment.

[0068] Common elements related to soil salinity include sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chlorine (Cl), and sulfur (S). By comparing the central wavelengths of these elements through the NIST database, the wavelengths of these elements in the spectrum are screened out, that is, the measured spectral intensity of the elements to be measured in the atomic emission spectrum is obtained. The elements to be measured may include sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chlorine (Cl), and sulfur (S).

[0069] Subsequently, the measured spectral intensity of the element is corrected according to the water content of the soil at different depths. The intensity correction formula is: ; Where is the finally corrected spectral intensity, is the measured spectral intensity. is the exponential decay factor, is a constant representing the influence of moisture on the spectral intensity, is the soil water content, is the soil water content corresponding to the measured spectral intensity , and the exponential decay factor mainly corrects the influence of the water content on reducing the spectral intensity. is the polynomial coefficient obtained by fitting experimental data, reflecting the non-linear influence of the moisture content on the spectral intensity.

[0070] After obtaining the corrected spectral intensity, the composition of the soil at different depths is detected based on the corrected spectral intensity of the relevant elements.

[0071] The device provided by the embodiment of the present invention can correct the measured spectral intensity through the water content of the soil at the depth corresponding to the atomic emission spectrum, reduce the influence of the moisture content on the spectral intensity, and thus improve the accuracy of composition detection.

[0072] Based on any of the above embodiments, the composition detection unit includes an element content detection subunit for: Obtaining the standard spectral intensity of different elements in the standard soil sample based on the laser-induced breakdown spectroscopy technology; The elemental contents of different elements are fitted with the standard spectral intensities to obtain the standard curves of different elements; The corrected spectral intensities of relevant elements are matched with the standard curves of different elements, and the elemental contents of soils at different depths are obtained based on the matching results.

[0073] Specifically, in addition to obtaining the elemental categories of soils at different depths, it is also necessary to detect the contents of various elements. For the detection of elemental contents, it can be achieved by matching with the standard curves.

[0074] In the laboratory, according to the basic components of the soil in the field area to be measured, a series of standard soil samples with known concentrations are selected or prepared. These standard soil samples should be similar to the samples to be measured in the field in terms of matrix components.

[0075] Use a laser-induced breakdown spectroscopy (LIBS) instrument to measure the spectral signals of each standard soil sample in the laboratory. Record the spectral intensity I of the element to be measured target Plot the standard curve, with the element concentration C target and the spectral intensity I target fitted to obtain the standard curves of different elements in the soil. Conduct LIBS measurement on the soil sample to be measured in the field, record the spectral intensity of the element to be measured, and correct it to obtain the corrected spectral intensity of the relevant element.

[0076] According to the spectral responses of the standard soil samples with different matrix components in the laboratory, compare the corrected spectral intensity of the soil to be measured with the laboratory standard curves, and select the standard curve closest to the soil to be measured to reduce the matrix effect. Substitute the corrected spectral intensity I target,field of the relevant element into the corresponding matrix-matched standard curve to calculate the concentration of the relevant element to be measured.

[0077] The device provided by the embodiment of the present invention realizes rapid and low-cost detection of elemental contents by matching the corrected spectral intensities of relevant elements with the standard curves of different elements and obtaining the elemental contents of soils at different depths based on the matching results.

[0078] Based on any of the above embodiments, the composition detection unit includes a water-soluble total salt content detection subunit for: Detecting the water-soluble total salt content of soils at different depths based on the corrected spectral intensity and a trained water-soluble total salt content detection model, where the water-soluble total salt content detection model is trained based on the sample spectral intensity and its corresponding water-soluble total salt content label.

[0079] Specifically, for the composition detection of soils at different depths, in addition to detecting the elemental contents, the water-soluble total salt content in the soil can also be detected.

[0080] After correcting the obtained atomic emission spectrum to obtain the corrected spectral intensity, the water-soluble total salt content of soils at different depths is detected by a pre-trained water-soluble total salt content detection model. The corrected spectral intensity is input into the water-soluble total salt content detection model to obtain the water-soluble total salt content output by the water-soluble total salt content detection model. Among them, the water-soluble total salt content detection model can be an artificial neural network model.

[0081] Before that, a large number of sample spectral intensities and their corresponding water-soluble total salt content label data can be collected to train the initial model, and the trained model is the water-soluble total salt content detection model.

[0082] The sample spectral intensity is the intensity of the electromagnetic wave emitted or absorbed by the sample, which reflects the radiation or absorption ability of the soil sample at a specific wavelength and can be obtained by performing spectral measurement on the soil sample with a spectrometer.

[0083] Taking the sample spectral intensity data as the input feature and the water-soluble total salt content label data as the output target. Using the selected algorithm and model structure, the input data is trained. During the training process, the model will continuously adjust its parameters to minimize the error between the predicted value and the actual value. During the training process, methods such as cross-validation can be used to evaluate the performance of the model. By calculating the error between the predicted value and the actual value (such as mean square error, root mean square error, etc.), the prediction ability of the model is evaluated.

[0084] The device provided by the embodiment of the present invention can quickly detect the water-soluble total salt content of soils at different depths based on the corrected spectral intensity and the trained water-soluble total salt content detection model.

[0085] Based on any of the above embodiments, the spectral data processing module further includes a preprocessing unit for: Before screening the spectral lines of the atomic emission spectra of soils at different depths, preprocess the atomic emission spectra of soils at different depths; The preprocessing includes background removal of the atomic emission spectrum based on wavelet transform background subtraction, rejection of abnormal spectra, and averaging of the spectral intensities of consecutive multiple atomic emission spectra.

[0086] Specifically, in order to further improve the accuracy of soil component detection, before screening the spectral lines of the atomic emission spectra of soils at different depths, the atomic emission spectra of soils at different depths can also be preprocessed.

[0087] Among them, the process of background removal of the atomic emission spectrum based on wavelet transform background subtraction is as follows: For an atomic emission spectrum signal , it can be decomposed into low-frequency (approximate) and high-frequency (detail) components using the discrete wavelet transform (DWT). The wavelet decomposition can be expressed as: ; where are the coefficients of the low-frequency approximate component, reflecting the low-frequency background information of the signal, are the coefficients of the high-frequency detail component, reflecting the details and spectral line information of the signal, is the low-frequency part (approximate function) of the wavelet basis function, is the high-frequency part (detail function) of the wavelet basis function, represents the number of layers of wavelet decomposition, and k represents the position of the wavelet basis function.

[0088] The background information is usually mainly concentrated in the low-frequency approximate component . Therefore, the background can be removed by extracting the low-frequency component. The specific steps include: Select the decomposition layer: Select an appropriate number of wavelet decomposition layers , determined through experiments, so that the background and spectral lines can be effectively separated. Retain the low-frequency component: In the -layer wavelet decomposition, the low-frequency approximate component mainly contains background information. It can be removed from the signal or directly processed separately.

[0089] After removing the low-frequency component, the remaining signal consists of the high-frequency detail component . These components contain the main spectral line information. Therefore, the signal after removing the background can be expressed as: ; Optionally, abnormal spectra can be removed based on the cosine similarity. The process is as follows: Suppose there are m spectra, and each spectrum is represented as (where i = 1, 2, 3......, m). Calculate the cosine similarity between each pair of spectra to construct an m×m similarity matrix S, where the element represents the similarity between spectra and , and is expressed by the formula: ; where n is the number of wavelengths in the spectrum, is the light intensity of the -th wavelength in the -rd spectrum. Since the similarity between different spectra needs to be calculated, is the light intensity of the k-th wavelength in the -th spectrum.

[0090] To quantify the similarity of each spectrum to all other spectra, the average similarity of each spectrum to the other spectra can be calculated : ; Here, denotes the average similarity of spectrum relative to the other spectra, m is the number of spectra. A lower value means that the spectrum is abnormal. Calculate the mean μ and standard deviation σ of the average similarity of all spectra . Set the threshold to (p is a constant, usually 1 or 2), and consider the spectra with an average similarity lower than this threshold as abnormal spectra, which can be expressed by the formula: ; ; where T is the set threshold. The spectra that meet this condition are abnormal spectra and should be excluded.

[0091] Optionally, based on the median averaging method, the spectral intensities of multiple consecutive atomic emission spectra are averaged as follows: For the atomic emission spectra collected multiple times at the same position, set them as a (where i = 1, 2,......, M; a = 1, 2,......, n) spectral matrix. For the wavelength position a, extract the intensity values of all spectra at this position at this detection point . Calculate the median of each position to obtain the value of the median-averaged spectrum , which can be expressed by the formula: ; where, represents the set of light intensity values of all spectra at wavelength a. represents the light intensity value of the m-th spectrum at wavelength a.

[0092] The device provided by the embodiments of the present invention can further improve the accuracy of detecting the element content and water-soluble total salt content by preprocessing the atomic emission spectra of soils with different depths.

[0093] Based on any of the above embodiments, Figure 6 is a schematic flow chart of the detection method provided by the present invention. As Figure 6 shown, the detection method includes: S1. Preprocess the atomic emission spectra of the soil at different depths; the preprocessing includes background removal from the atomic emission spectra based on wavelet transform background subtraction, rejection of abnormal spectra, and averaging of the spectral intensities of consecutive multiple atomic emission spectra.

[0094] S2. Based on the wavelengths of the elements related to soil salinity, screen the spectral lines of the atomic emission spectra of the soil at different depths to obtain the measured spectral intensities of the elements to be measured in the atomic emission spectra; based on the water content of the soil corresponding to the depth of the atomic emission spectra, correct the measured spectral intensities to obtain the corrected spectral intensities of the relevant elements.

[0095] S3. Based on the laser-induced breakdown spectroscopy technology, obtain the standard spectral intensities of different elements in the standard soil samples; fit the element contents of different elements with the standard spectral intensities to obtain the standard curves of different elements; match the corrected spectral intensities of the relevant elements with the standard curves of different elements, and obtain the element contents of the soil at different depths based on the matching results.

[0096] S4. Based on the corrected spectral intensities and the trained water-soluble total salt content detection model, detect the water-soluble total salt content of the soil at different depths, and the water-soluble total salt content detection model is trained based on the sample spectral intensities and their corresponding water-soluble total salt content labels.

[0097] Figure 7 is a schematic diagram of the experimental verification results provided by the present invention. As Figure 7 shown, the abscissa is the actual value of the soil salinity content (g / kg), and the ordinate is the detected value of the soil salinity content (g / kg) detected by the water-soluble total salt content detection model. The blue is the training set data for constructing and training the model; the red is the test set data for evaluating the generalization ability of the model.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for detecting the improvement status of saline-alkali land, characterized in that: include: A protection and guidance component, which is placed in a deep soil pit at a point to be detected; A plurality of moisture content detectors are installed on the outer side wall of the protection and guide assembly, and are used to detect the moisture content of the soil at different depths of the point to be detected; A soil composition detection system is detachably connected to the protection and guide assembly, and is used to emit laser to the soil at different depths of the detection point to generate plasma, measure the atomic emission spectrum, and perform composition detection on the soil at different depths based on the atomic emission spectrum and the water content; A control system, connected to the protection and guidance component, the soil composition detection system, and the water content detector, respectively, for controlling the protection and guidance component to drive the soil composition detection system to move in a vertical direction on the ground, and the control system is also used to receive measurement data from the water content detector; The soil component detection system comprises a spectral data processing module, and the spectral data processing module is used to detect the components of the soil at different depths based on the atomic emission spectrum and the water content; The spectral data processing module comprises: A spectral line screening unit, used to screen the spectral lines of the atomic emission spectra of the soils at different depths based on the wavelengths of elements related to soil salinity, to obtain the measured spectral intensity of the elements to be measured in the atomic emission spectra; A spectrum correction unit, used to correct the measured spectrum intensity based on the water content of the soil at the depth corresponding to the atomic emission spectrum, so as to obtain the corrected spectrum intensity of the relevant element; The component detection unit is used to detect the components of the soil at different depths based on the corrected spectral intensity of the relevant elements.

2. The saline-alkali land improvement condition detection device according to claim 1, characterized in that: The protection and guidance component comprises: A guide rail, the soil composition detection system is installed on the guide rail, and the control system controls the guide rail to move up and down; There are detection windows corresponding to different depths. When the soil composition detection system reaches the current depth, the control system controls the current detection window to open to detect the composition of the soil at the current depth, and closes the current detection window after the detection is completed.

3. The saline-alkali land improvement condition detection device according to claim 2, characterized in that: The protection and guidance assembly includes a protective shell and a waterproof coating, and also includes: a baffle, mounted on the top of the protection and guide assembly; A protective cover and a waterproof cover installed outside the detection window; A base is connected to the guide rail and is used to fix the guide rail.

4. The saline-alkali land improvement condition detection device according to any one of claims 1 to 3, characterized in that: The soil component detection system comprises: A laser, used for emitting pulsed laser to the soil at different depths, thereby forming laser plasma; A spectrometer, used for receiving the atomic emission spectrum emitted by the laser plasma; An optical path module, used for processing the optical paths of the laser and the spectrometer; A three-dimensional mobile platform is used to carry the laser, the spectrometer and the optical path module.

5. The saline-alkali land improvement condition detection device according to claim 1, characterized in that: The spectrum correction unit is specifically used for: The measured spectral intensity is corrected based on the following formula: ； in is the final corrected spectral intensity, is the measured spectral intensity, is the exponential decay factor, is a constant, which indicates the effect of moisture on the spectral intensity. is the water content of the soil, To measure the spectral intensity The corresponding soil moisture content, is the polynomial coefficient, reflecting the nonlinear effect of water content on spectral intensity.

6. The device for detecting the improvement status of saline-alkali land according to claim 1, characterized in that: The component detection unit includes an element content detection subunit, which is used to: Based on the laser-induced breakdown spectroscopy technique, the standard spectral intensity of different elements in the standard soil sample is obtained; Fitting the element contents of different elements with the standard spectrum intensity to obtain standard curves of different elements; The corrected spectral intensity of the relevant elements is matched with the standard curves of the different elements, and the element content of the soil at different depths is obtained based on the matching results.

7. The device for detecting the improvement status of saline-alkali land according to claim 1, characterized in that: The component detection unit includes a water-soluble total salt content detection subunit, which is used for: Based on the corrected spectral intensity and the trained water-soluble total salt content detection model, the water-soluble total salt content of soil at different depths is detected. The water-soluble total salt content detection model is trained based on the sample spectral intensity and its corresponding water-soluble total salt content label.

8. The device for detecting the improvement status of saline-alkali land according to claim 1, characterized in that: The spectral data processing module also includes a preprocessing unit, which is used to: Before screening the spectral lines of the atomic emission spectra of the soils at different depths, preprocessing the atomic emission spectra of the soils at different depths; The preprocessing includes removing the background of the atomic emission spectrum based on the background subtraction of wavelet transform, eliminating abnormal spectra, and averaging the spectral intensities of multiple consecutive atomic emission spectra.

9. A detection method, applied to the saline-alkali land improvement condition detection device according to any one of claims 1 to 8, characterized in that: The method comprises: The moisture content of the soil at different depths at the point to be detected is obtained by using multiple moisture content detectors, wherein the multiple moisture content detectors are installed on the outer side wall of the protection and guide assembly, and the protection and guide assembly is placed in a deep soil pit at the point to be detected; Controlling the protection and guide assembly to drive the soil composition detection system to move in a vertical direction on the ground; The soil composition detection system emits laser to the soil at different depths of the detection point to generate plasma, measures the atomic emission spectrum, corrects the atomic emission spectrum based on the water content, and detects the composition of the soil at different depths based on the corrected atomic emission spectrum; The correcting the atomic emission spectrum based on the water content and detecting the components of the soil at different depths based on the corrected atomic emission spectrum comprises: Based on the wavelength of the elements related to soil salinity, the spectral lines of the atomic emission spectra of the soils at different depths are screened to obtain the measured spectral intensity of the elements to be measured in the atomic emission spectra; Based on the water content of the soil at the depth corresponding to the atomic emission spectrum, the measured spectrum intensity is corrected to obtain the corrected spectrum intensity of the relevant element; Based on the corrected spectral intensity of the relevant elements, the components of the soil at different depths are detected.

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