Method for measuring thickness of black soil layer under straw returning condition by using ground penetrating radar technology
By burying markers on the ground penetrating radar survey line and using ground penetrating radar technology to measure the thickness of the black soil layer under the conditions of straw return to the field, the problem of accurate measurement of the soil thickness after straw return to the field is solved, and efficient and low-cost continuous detection of the black soil layer thickness is achieved, providing support for technological improvement and sustainable agricultural development.
Patent Information
- Application Number
- CN202510939618.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-08
- Publication Date
- 2025-09-12
AI Technical Summary
Existing ground-penetrating radar technology is difficult to accurately measure the thickness of the black soil layer under the condition of straw return to the field. The reason is that the heterogeneous composite structure formed by straw and soil causes electromagnetic wave reflection and signal attenuation. The signal energy decays rapidly, making it difficult to obtain continuous spatial variation information of the soil layer thickness.
By burying markers on the survey line, the dielectric constant of the markers is significantly different from that of the soil. The ground penetrating radar is used to scan and process the image, and the soil thickness is accurately measured based on the position of the markers. The markers are buried at the boundary between the black soil layer and the loess parent material layer to ensure accurate scanning by the radar antenna.
Continuous detection of the thickness of the black soil layer under the condition of straw return to the field was achieved, with an error range of 6.2%-13.5%, providing a scientific basis for technological improvement and sustainable agricultural development, and reducing data collection costs and labeling difficulty.
Smart Images
Figure CN120627977A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of soil layer thickness detection, and in particular relates to a method for measuring the thickness of a black soil layer under straw return conditions by using ground penetrating radar technology. Background Art
[0002] At present: Black soil is an important carbon pool in terrestrial ecosystems and a core carrier of food security. Its thickness changes directly affect soil productivity and carbon sequestration function. However, long-term high-intensity tillage has led to the loss of soil organic matter and increased erosion in the black soil area, a significant decline in yields, and a serious threat to regional agricultural sustainability. Conservation tillage is a modern farming technology system with crop straw mulching and no-till (or minimum tillage) sowing as its main content. It can effectively reduce soil wind and water erosion, increase soil fertility and moisture conservation and drought resistance, and improve agricultural ecology and economic benefits. At present, the Northeast region mainly adopts two types of straw return modes, one is surface mulching with different fragment lengths, and the other is soil mixing with different crushing degrees and burial depths.
[0003] Accurately assessing soil thickness and its spatial distribution under conservation tillage practices in Northeast China's black soil regions is crucial for protecting these resources. Ground-penetrating radar (GPR) currently demonstrates its advantages in probing homogeneous soil profiles. However, the heterogeneous composite structure of soil layers formed under straw incorporation can induce multiple reflections and attenuation of electromagnetic waves, making it difficult to obtain continuous spatial variations in soil thickness under these conditions.
[0004] Through the above analysis, the problems and defects of the existing technology are as follows:
[0005] After straw is returned to the field, it mixes with the soil, forming a "soil-straw" heterogeneous composite structure. The significant difference in dielectric constant between straw and soil causes electromagnetic waves to reflect, refract, and scatter at the interface between the two media, resulting in rapid attenuation of signal energy. Within this heterogeneous structure, the distribution of straw fragments is highly random, and the strong reflection signals they generate can mask echoes from the actual soil interface, blurring soil layer boundaries in radar images and making it difficult to accurately interpret soil thickness.
[0006] The difficulty in addressing these issues and deficiencies lies in the complex coupling between straw's physical properties (moisture content, fragment size) and soil properties, making it difficult to establish a universal electromagnetic propagation model. Intelligent recognition algorithms for the soil-straw interface (such as machine learning-driven image segmentation) need to be developed, but the training data would need to cover radar images of different landfill patterns and soil types, making data acquisition expensive and labeling difficult. To address these issues, soil markers can be deployed to identify soil layer characteristics, enabling accurate, efficient, and cost-effective acquisition of soil thickness information.
[0007] The significance of addressing these issues and deficiencies is that it will clarify the applicability and accuracy of GPR for measuring black soil thickness under straw return conditions, thereby providing data support for improving GPR technology for black soil thickness monitoring. Furthermore, it will promote the precise application of GPR in complex farmland environments and provide important scientific evidence and technical reference for the implementation of sustainable agricultural development policies. Summary of the Invention
[0008] In view of the problems existing in the prior art, the present invention provides a method for measuring the thickness of the black soil layer under the condition of returning straw to the field by using ground penetrating radar technology.
[0009] The present invention is achieved by using ground penetrating radar technology to measure the thickness of the black soil layer under the condition of returning straw to the field, comprising:
[0010] Step 1: determine the area to be detected on the land with different straw return methods;
[0011] Specifically, the selectable straw return methods include but are not limited to straw mulching and straw mixing. Before proceeding to the next step, the area of the selected detection area should be preliminarily measured.
[0012] Step 2: Multiple survey lines can be set up according to the size of the detection area. The length of the survey lines is measured and an appropriate number of soil profiles are laid out along the survey lines to record the thickness of the black soil layer. The ground penetrating radar antenna is selected based on the observed black soil layer thickness.
[0013] According to the detection area measured in the previous step, set an appropriate number of survey lines to cover the entire detection area. The survey lines can be appropriately increased in areas with sudden changes in terrain, and all survey lines are distributed in the same direction.
[0014] Step 3: bury a marker in the above profile at the boundary between the black soil layer and the loess parent material layer, and record the actual buried depth of the marker and mark the corresponding survey line position;
[0015] The dielectric constant of the marker should be significantly different from the dielectric constant of the soil. The length of the marker should be greater than or equal to the width of the radar antenna, and the burial direction should be perpendicular to the survey line direction to ensure that the radar antenna can accurately scan the laid marker.
[0016] Step 4: Level the land on both sides of the survey line and remove any large clods of soil or rocks.
[0017] The land is leveled according to the conditions of the selected detection area, mainly to remove larger obstacles on the survey line to reduce the bumpiness of the ground penetrating radar wheels, ensure the clarity of the radar image, and ensure that there is no deviation between the measured distance and the actual distance of the survey line.
[0018] Step 5: Use the ground penetrating radar to scan along the survey line and mark the location of the marker in the ground penetrating radar.
[0019] Step 6: Process and read the radar image after scanning is completed.
[0020] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows:
[0021] The present invention provides a method for measuring the thickness of black soil layers under straw-returning conditions using ground-penetrating radar technology. Ground-penetrating radar can be used to continuously detect the thickness of black soil layers under protective tillage practices in Northeast China's black soil region, obtaining continuous spatial distribution characteristics of the black soil layer thickness. Field experiments show that the error of ground-penetrating radar in detecting soil layer thickness under straw-returning conditions is within a range of 6.2%-13.5%. The present invention is simple and fast to operate, with minimal soil disturbance, and can be used for continuous detection of soil layer thickness under heterogeneous structures. It can clarify the applicability and accuracy of ground-penetrating radar in measuring black soil layer thickness under straw-returning conditions, thereby providing data support for technical improvements in ground-penetrating radar monitoring of black soil thickness. Furthermore, it can provide important scientific basis and technical reference for the implementation of agricultural sustainable development policies. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0023] Figure 1 This is a flow chart of a method for measuring the thickness of the black soil layer under the condition of returning straw to the field using ground penetrating radar technology provided by an embodiment of the present invention.
[0024] Figure 2 Result diagram of a specific embodiment of the present invention: thickness variation of black soil layer on slope (A) is bare soil slope (B) is straw covered slope (C) is straw chopped mixed slope. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0026] In view of the problems existing in the prior art, the present invention provides a method for measuring the thickness of the black soil layer under the condition of straw return to the field by using ground penetrating radar technology. The present invention is described in detail below with reference to the accompanying drawings.
[0027] like Figure 1 As shown, the method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology provided by the embodiment of the present invention includes:
[0028] S101, determining the area to be detected on the land with different straw return methods;
[0029] S102, setting a plurality of survey lines according to the size of the detection area, measuring the length of the survey lines, laying out an appropriate number of soil profiles along the survey lines, and recording the thickness of the black soil layer. Based on the observed black soil layer thickness, a ground penetrating radar antenna is selected;
[0030] S103, burying a marker in the above profile at the boundary between the black soil layer and the loess parent material layer, and recording the actual buried depth of the marker and marking the corresponding survey line position;
[0031] S104, appropriately leveling the land on both sides of the survey line to remove large soil and rocks;
[0032] S105, scanning along the survey line using a ground penetrating radar, and marking the position of the marker in the ground penetrating radar;
[0033] S106, after the scanning is completed, the radar image is processed and read.
[0034] In step S101 in the embodiment of the present invention, the straw returning method mainly includes straw covering and straw mixing.
[0035] In step S101 in the embodiment of the present invention, the area of the region to be detected can be selected based on the area required for actual research.
[0036] In step S102 in the embodiment of the present invention, the survey lines are all distributed along the same direction, and the survey lines may be denser in areas where the terrain changes suddenly.
[0037] In step S103 in the embodiment of the present invention, the dielectric constant of the marker should be significantly different from the dielectric constant of the soil.
[0038] In step S103 in the embodiment of the present invention, the length of the marker is greater than or equal to the width of the radar antenna.
[0039] In step S103 in the embodiment of the present invention, the burying direction of the marker is perpendicular to the survey line direction.
[0040] In step S104 in the embodiment of the present invention, the land on both sides of the survey line is the land passed by the ground penetrating radar ranging wheels, and is leveled to ensure that the measured distance has no deviation from the actual distance of the survey line.
[0041] In step S105 in the embodiment of the present invention, before using the ground penetrating radar to scan the selected area, it is ensured that the radar antenna is at the center of the marker.
[0042] GPR image processing generally involves the following steps: time zero, background removal, gain adjustment, and other operations, ultimately resulting in a time / depth profile image. After processing the radar image, the actual buried depth of the marker, typically represented as a parabola in the radar image, is compared and analyzed based on the marker's position recorded in step S103. The ground-penetrating radar's detection accuracy can be determined by comparing the actual depth of the marker with the reading in the radar image. Field experiments conducted by the present invention have shown that the error range of the ground-penetrating radar in detecting soil thickness under straw-covered and straw-mixed conditions is 6.2%-13.5%. Furthermore, the electromagnetic wave variation characteristics are analyzed based on the marker's position in the radar image, and the soil thickness can be extracted based on these electromagnetic wave variation characteristics.
[0043] The present invention will be further described below in conjunction with specific experiments.
[0044] Three sloping fields with different conservation tillage practices were selected within the study area: a straw-free slope, 180 m long and 70 m wide; a straw-covered slope, 170 m long and 70 m wide; and a straw-mixed slope, 140 m long and 60 m wide. All three sloping fields were tilled along the ridge and planted with corn. Three survey lines were evenly spaced across the study area, measuring the depth using a 400 MHz antenna combined with a profiling method, with verification performed using a traditional excavation-profiling method. Excavation was performed at a point along each survey line to measure the depth of the black soil layer. Markers (iron pipes) were placed perpendicular to the survey lines to verify measurement accuracy. The iron pipes were 60 cm long and 5 cm in diameter and were placed at the interface between the black soil and loess parent material. Due to the significant difference in dielectric properties between the iron pipes and the soil, significant jumps appear in the radar image, allowing for correction of soil thickness measurements.
[0045] The soil depth can be directly read from the processed radar image. The accuracy of the soil thickness detected by the ground-penetrating radar can be obtained from the actual field iron pipe installation depth and the iron pipe burial depth obtained from the radar image, as shown in Table 1 below. After calculation and analysis, it was found that there was no significant difference between the actual burial depth of the iron pipe and the iron pipe depth detected by the ground-penetrating radar.
[0046] Table 1 Actual buried depths of different slope markers and depths measured by ground penetrating radar
[0047]
[0048] Note: P>0.05 indicates no significant difference.
[0049] The thickness distribution characteristics of the black soil layer on the three slopes were obtained based on the slope radar images, such as Figure 2As shown in the figure, the average black soil thicknesses for bare soil sloping farmland, straw-mulched sloping farmland, and straw-shredded mixed sloping farmland were 29.12 cm, 28.59 cm, and 34.63 cm, respectively. Overall, the black soil thickness for bare soil sloping farmland increased from the top to the bottom of the slope, ranging from 16.44 to 48.68 cm. The black soil thickness on straw-mulched slopes was unevenly distributed, ranging from 20.02 to 46.55 cm. The soil layer was relatively thick on one side of the slope, while the thickness remained relatively stable elsewhere. However, the soil layer was relatively thin in the middle of the slope. The overall black soil thickness on straw-shredded mixed slopes ranged from 19.34 to 48.61 cm. The soil layer was thinner at the top of the slope, then increased, decreased, and then increased along the slope, with a slight increase near the bottom.
[0050] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.
Claims
1. A method for measuring the thickness of black soil layer under straw return conditions using ground penetrating radar technology, characterized in that: The method for detecting the thickness of the black soil layer in the Northeast black soil region under the condition of returning straw to the field by using ground penetrating radar technology comprises: Step 1: determine the area to be detected on the land with different straw return methods; Step 2: Set up multiple survey lines according to the size of the detection area, measure the length of the survey lines, lay out an appropriate number of soil profiles along the survey lines, and record the thickness of the black soil layer. Select the ground penetrating radar antenna based on the observed black soil layer thickness; Step 3: bury a marker in the above profile at the boundary between the black soil layer and the loess parent material layer, and record the actual buried depth of the marker and mark the corresponding survey line position; Step 4: Level the land on both sides of the survey line and remove any large clods of soil or rocks. Step 5: Use ground penetrating radar to scan along the survey line and mark the position of the marker in the ground penetrating radar; Step 6: Process and read the radar image after scanning is completed.
2. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step one, the straw returning method mainly includes straw covering and straw mixing.
3. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step 1, the area of the region to be detected can be selected based on the area required for actual research.
4. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step 2, the survey lines are all distributed in the same direction, and the survey lines can be denser in areas with sudden changes in terrain.
5. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step three, the dielectric constant of the marker should be significantly different from the dielectric constant of the soil, and the length of the marker should be greater than or equal to the width of the radar antenna.
6. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step three, the marker is buried perpendicular to the survey line direction.
7. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step 4, the land on both sides of the survey line is the land passed by the ground penetrating radar ranging wheels, and it is leveled to ensure that there is no deviation between the measured distance and the actual distance of the survey line.
8. The method for measuring the thickness of the black soil layer under the straw return condition using ground penetrating radar technology according to claim 1, characterized in that: In step five, before scanning the selected area with the ground penetrating radar, ensure that the radar antenna is centered over the marker.