CN103185708B - Online detection apparatus and method for soil elements - Google Patents
Online detection apparatus and method for soil elements Download PDFInfo
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- CN103185708B CN103185708B CN201110458289.8A CN201110458289A CN103185708B CN 103185708 B CN103185708 B CN 103185708B CN 201110458289 A CN201110458289 A CN 201110458289A CN 103185708 B CN103185708 B CN 103185708B
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- 239000002689 soil Substances 0.000 title claims abstract description 230
- 238000001514 detection method Methods 0.000 title claims abstract description 131
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 44
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- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 17
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- 239000011574 phosphorus Substances 0.000 claims description 17
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Abstract
The invention relates to an online detection apparatus and method for soil elements. The apparatus comprises a soil-penetrating detection component and a laser irradiation and detection system, wherein the soil-penetrating detection component is connected with the laser irradiation and detection system through optical fibers; the soil-penetrating detection component comprises a housing and focusing lenses disposed in the housing; the laser irradiation and detection system comprises a laser irradiation system, a laser acquisition system and a control system; the laser irradiation system is connected with a focusing lens and the control system respectively; and the laser acquisition system is connected with the other focusing lens and the control system respectively. The method comprises the following steps of soil-penetrating detection, acquisition of attenuation spectrum information of soil plasma, formation of a laser plasma spectrum of to-be-detected soil and calculation of element components of the to-be-detected soil. The apparatus and the method can realize on-line and in-situ detection of the soil in a field environment.
Description
Technical Field
The invention relates to a soil fertilizer detection method and a device, in particular to a soil element (especially nitrogen phosphorus potassium element) online detection device and a method for carrying out real-time online rapid detection and analysis on soil nutrients in a field.
Background
The soil nutrient detection is a basic link of soil testing and formulated fertilization, is an important prerequisite and guarantee for fine fertilization management, and determines scientific and reasonable fertilization types, quantity and time by detecting important information such as nitrogen, phosphorus, potassium, organic matters, moisture, conductivity, pH value and the like in soil and coordinately analyzing the relationship among soil fertility, crop fertilizer demand and fertilizer nutrient contentAnd a method. At present, a large number of large (medium) type detecting instruments such as a high-efficiency gas chromatograph, an ion chromatograph, a continuous flow injection analyzer, a spectrophotometer and the like are adopted for analysis in soil nutrient laboratory detection, although the simultaneous measurement of multiple chemical components can be realized, the detection result is stable, and the precision is higher. However, in the practical application process, the existing method also has the following disadvantages: first, the detection price is high. Limited by detection instruments, personnel training and chemical reagent cost, the test cost of a single sample in the current soil detection laboratory is about 100-200 yuan, and most farmers are difficult to actively carry out farmland nutrient detection under the condition of unobvious output and input profit conditions. Second, the detection results are poor in representativeness. The per capita area of China is less than 0.1hm2The production management is dispersed, and the difference of the fertility of the cultivated land is large. However, the field sampling unit proposed by technical Specification (trial) for soil testing, formulation and fertilization is 5-15 hm2. The soil sample collection method is applicable to large-scale farms in the north of China, but not to small-scale farmlands ubiquitous in China. Thirdly, the soil testing timeliness is poor. The period from collecting soil samples, sending the soil samples to a laboratory above the county level, measuring the soil samples by the laboratory, feeding back soil measurement information, and finally giving a fertilization guidance suggestion is at least 5-10 days. In practical application, farmers often obtain the analysis result of a laboratory and miss the optimal time for crop fertilization. Therefore, the method becomes a bottleneck problem for realizing cost-saving efficiency-increasing and fine variable fertilization in fine agriculture practice. Compared with a conventional laboratory analysis method, the soil online rapid test technology has the advantages of better timeliness, lower cost, simpler test equipment and higher test precision, and only needs to meet the application requirement, so the technology is a research hotspot in the field of agricultural soil nutrient measurement, and the rapid and reliable soil fertilizer online test method needs to be promoted and researched along with popularization and application of soil testing formula fertilization in the national range.
The soil is a complex and multi-phase polymer, and the on-line rapid detection technology of soil nutrients influenced by multiple factors is always a technical bottleneck that accurate agricultural front-end information acquisition is difficult to break through, so that a rapid on-line real-time detection method for nitrogen, phosphorus and potassium in farmland field soil is explored, and special detection instrument equipment is developed, so that the method has important practical significance for efficiently and accurately knowing the spatial distribution condition of farmland soil nutrients, reducing the application of soil fertilizers, reducing environmental pollution, improving the quality of agricultural products, ensuring the rapid and sustainable development of modern agriculture and promoting the progress of agricultural science and technology.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method and a device for detecting elements such as nitrogen, phosphorus and potassium in soil in a field environment, so as to solve the technical bottleneck of on-line rapid detection of soil and fertilizer and realize on-line and in-situ detection of soil.
In order to achieve the aim, the invention provides an on-line soil element detection device, which comprises an embedded detection part and a laser emission and detection system, the soil-entering detection part is connected with the laser emission and detection system through an optical fiber and comprises a shell and a focusing lens arranged in the shell, the laser emitting and detecting system comprises a laser emitting system, a laser collecting system and a control system, the laser emission system is respectively connected with the focusing lens and the control system, the laser collection system is respectively connected with the focusing lens and the control system, the laser acquisition system is used for acquiring atomic spectrum signals generated in the soil to be detected in the plasma attenuation process and transmitting the atomic spectrum signals to the control system, and the control system processes and analyzes the atomic spectrum signal and compares the atomic spectrum signal with a soil component quantitative analysis model to calculate the content of the element components in the soil to be detected.
The soil element on-line detection device comprises a soil-breaking mechanism, wherein the soil-breaking mechanism is arranged at the front end of the shell and used for reducing the working resistance of the shell advancing in soil, the soil-breaking mechanism comprises a plow-shaped opener, and the plow-shaped opener is arranged at the bottom of the front end of the shell.
The soil element on-line detection device is characterized in that the soil breaking mechanism further comprises a soil breaking blade, and the soil breaking blade is arranged above the plow-shaped furrow opener and is installed on the shell.
In the soil element online detection device, the soil penetration detection component further comprises a scraper for leveling the detection surface of the soil to be detected, and the scraper is arranged behind the plow-shaped furrow opener and mounted at the bottom end of the shell.
In the above online soil element detection device, the soil penetration detection component further includes a light shielding plate for shielding interference of external stray light, and the light shielding plate is installed at the bottom of the housing and is arranged opposite to the scraper.
In the soil element on-line detection device, the laser collection system includes a monochromator, a direct frequency synthesizer, a detection controller and a delay generator, the monochromator is connected with the focusing lens through an optical fiber, the direct frequency synthesizer is connected with the monochromator, the detection controller is respectively connected with the monochromator and the control system, and the delay generator is respectively connected with the detection controller and the control system.
The soil element on-line detection device comprises a casing, a soil element detection component, a distance measurement sensor and a control system, wherein the soil element detection component further comprises the distance measurement sensor for detecting the soil penetration depth of the casing in real time, and the distance measurement sensor is installed at the upper end of the casing through a support and connected with the control system.
In order to better achieve the above object, the present invention further provides an online soil element detection method, which adopts the online soil element detection device, wherein the online soil element detection method comprises the following steps:
a. detecting the soil penetration, so that the soil penetration detection part reaches the specified depth of the soil to be detected;
b. collecting soil plasma attenuation spectrum information, starting a laser emission and detection system by a control system, emitting laser by the laser emission system, transmitting the laser into a focusing lens through an optical fiber, converging light rays by the focusing lens, and then directly irradiating the light rays on a soil surface to be detected to obtain an atomic spectrum signal generated in the soil plasma attenuation process to be detected, transmitting the atomic spectrum signal to a laser collection system through the optical fiber, collecting the atomic spectrum signal by the laser collection system, and transmitting the atomic spectrum signal to the control system after AD conversion;
c. forming a laser plasma spectrum of the soil to be detected, and processing and analyzing the atomic spectrum signal by the control system to obtain the laser plasma spectrum of the soil to be detected;
d. and calculating the content of the element components in the soil to be detected, and calculating to obtain the content of the element components in the soil to be detected by utilizing the laser plasma spectrum of the soil to be detected and a soil component quantitative analysis model.
The soil element online detection method comprises the following steps of:
s1, obtaining the laser plasma spectrum of the soil to be detected by adopting the steps a-c;
s2, establishing a spectrum data sample set, preprocessing the laser plasma spectrum, deleting data abnormal sample points of the laser plasma spectrum, and establishing the deleted data sample set of the laser plasma spectrum;
s3, establishing a soil component quantitative analysis model, adopting an internal standard method to correct and analyze the data sample set of the laser plasma spectrum according to the soil nutrient element characteristic plasma spectral line with the determined wavelength, and establishing the soil component quantitative analysis model.
In the above online detection method for soil elements, in step s3, the ratio of the spectral emission intensity at the wavelengths of 744.23nm and 746.83nm for soil nitrogen elements, 255.32nm and 253.56nm for soil phosphorus elements, and 766.49nm and 769.90nm for soil potassium elements to the emission intensity of internal standard elements is determined, and the quantitative analysis model for soil components is established by using a binary linear regression method.
The invention has the technical effects that: the method overcomes the defects of high price, low representativeness and poor timeliness of the traditional farmland soil fertilizer detection technology, solves the technical bottleneck of online rapid detection of the soil fertilizer, and realizes the online detection and the in-situ detection of the soil. The device can be directly hung on a tractor, realizes large-scale online detection of elements such as nitrogen, phosphorus and potassium in soil, generates a soil nutrient space distribution map in a short time, and effectively guides subsequent accurate agricultural quantitative change operation.
The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.
Drawings
FIG. 1 is a schematic structural diagram of a detection apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an inground detection element according to an embodiment of the present invention;
FIG. 3 is a plasma spectral characteristic line of nitrogen element in soil;
FIG. 4 is a plasma spectral characteristic line of phosphorus element in soil;
FIG. 5 is a soil potassium element plasma spectral characteristic line;
FIG. 6 is a flowchart of a detection method according to an embodiment of the present invention;
fig. 7 is a flowchart of establishing a soil composition quantitative analysis model according to an embodiment of the present invention.
Wherein the reference numerals
1 buried detecting member
11 casing
12 focusing lens
13 mechanism breaks ground
131 furrow opener
132 ground breaking edge
14 scraping board
15 light shading plate
16 distance measuring sensor
17 support
18 lens mounting base
2 laser emission and detection system
21 laser emission system
22 laser acquisition system
221 monochromator
222 direct frequency synthesizer
223 detection controller
224 time delay generator
23 control system
3 optical fiber
31 incident optical fiber
32 acquisition optical fiber
A detection point
B soil layer surface
C soil surface to be measured
a to d, s1 to s3
Detailed Description
The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:
referring to fig. 1, fig. 1 is a schematic structural diagram of a detection apparatus according to an embodiment of the present invention. The soil element online detection device comprises an underground detection part 1 and a laser emission and detection system 2, wherein the underground detection part 1 is connected with the laser emission and detection system 2 through an optical fiber 3, the underground detection part 1 comprises a shell 11 and a focusing lens 12 arranged in the shell 11, the shell is preferably made of steel, the laser emission and detection system 2 comprises a laser emission system 21, a laser acquisition system 22 and a control system 23, the laser emission system 21 is respectively connected with the focusing lens 12 and the control system 23, the laser acquisition system 22 is used for acquiring atomic spectrum signals generated in the plasma attenuation process of soil to be detected and transmitting the atomic spectrum signals to the control system 23, and the control system 23 processes and analyzes the atomic spectrum signals and compares and calculates the atomic spectrum signals with a soil component quantitative analysis model to obtain the atomic spectrum signals in the soil to be detected The content of the element component. In this embodiment, the optical fiber 3 includes an incident optical fiber 31 and a collecting optical fiber 32, preferably two focusing lenses 12 are provided, the two focusing lenses 12 are respectively positioned in the cavity of the housing 11 through the lens mounting seat 18, and the lens mounting seat 18 is adjusted to enable the focal points of the two focusing lenses 12 to be located on the soil surface to be measured C and to converge on the same detection point a. The upper end of the lens mounting seat 18 is respectively connected with an incident optical fiber 31 and a collecting optical fiber 32, and the positions of the incident optical fiber 31 and the collecting optical fiber 32 are adjusted and respectively fixed, so that the ports of the incident optical fiber 31 and the collecting optical fiber 32 are respectively positioned at the other focal point of the two focusing lenses 12.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an inground detection element according to an embodiment of the present invention. In this embodiment, the penetration detection component 1 further includes a soil breaking mechanism 13, the soil breaking mechanism 13 is disposed at the front end of the housing 11 and is configured to reduce the working resistance of the housing 11 advancing in the soil, the soil breaking mechanism 13 includes a furrow opener 131, preferably a furrow opener of a plow type structure, and the furrow opener 131 of the plow type structure is disposed at the bottom of the front end of the housing 11. The soil breaking mechanism 13 further includes a soil breaking blade 132, the soil breaking blade 132 is disposed above the furrow opener 131 and is mounted on the housing 11, or a rib is disposed between the furrow opener 131 and the housing 11, and the soil breaking blade 132 is disposed at a front end of the rib, or may be integrated with the rib. In this embodiment, the soil penetration detecting component 1 may further include a scraper 14 for leveling a surface C to be detected of the soil to be detected, and the scraper 14 is disposed behind the furrow opener 131 and installed at the bottom end of the housing 11. The soil penetration detecting component 1 may further include a light shielding plate 15 for shielding the interference of external stray light, so as to further improve the detection accuracy, wherein the light shielding plate 15 is installed at the bottom of the housing 11 and is disposed opposite to the scraper 14.
In this embodiment, the laser collecting system 22 includes a monochromator 221, a direct frequency synthesizer 222, a detection controller 223, and a delay generator 224, the monochromator 221 is connected to the focusing lens 12 through an optical fiber 3, the direct frequency synthesizer 222 is connected to the monochromator 221, the detection controller 223 is respectively connected to the monochromator 221 and the control system 23, and the delay generator 224 is respectively connected to the detection controller 223 and the control system 23. In order to realize the 'in-situ' detection of soil nutrients in the same soil depth, the soil penetration detection part 1 may further include a distance measuring sensor 16 for detecting the soil penetration depth of the housing 11 in real time, and the uniform depth of soil nutrient detection may be maintained by driving the corresponding electric control mechanical unit, and the distance measuring sensor 16 may be installed at the upper end of the housing 11 through a bracket 17 and connected to the control system 23.
Referring to fig. 6, fig. 6 is a flowchart of a detection method according to an embodiment of the invention. The invention discloses an online detection method of soil elements, which comprises the following steps:
step a, detecting the soil penetration, so that the soil penetration detection part 1 reaches the specified depth of the soil to be detected;
b, collecting soil plasma attenuation spectrum information, starting a laser emission and detection system 2 by a control system 23, emitting laser by a laser emission system 21, transmitting the laser into a focusing lens 12 through an optical fiber 3, converging light rays by the focusing lens 12, and then directly irradiating a soil surface C to be detected to obtain an atomic spectrum signal generated in the soil plasma attenuation process to be detected, transmitting the atomic spectrum signal to a laser collection system 22 through the optical fiber 3, and collecting the atomic spectrum signal by the laser collection system 22, performing AD conversion on the atomic spectrum signal and transmitting the atomic spectrum signal to the control system 23;
c, forming a laser plasma spectrum of the soil to be detected, and processing and analyzing the atomic spectrum signal by the control system 23 to obtain the laser plasma spectrum of the soil to be detected;
and d, calculating the content of the element components in the soil to be detected, and calculating to obtain the content of the element components in the soil to be detected by utilizing the laser plasma spectrum of the soil to be detected and a soil component quantitative analysis model.
Referring to fig. 7, fig. 7 is a flowchart of establishing a soil composition quantitative analysis model according to an embodiment of the present invention. The soil component quantitative analysis model can be obtained by adopting the following steps:
step s1, obtaining the laser plasma spectrum of the soil to be detected by adopting the steps of the steps a to c;
step s2, establishing a spectrum data sample set, preprocessing the laser plasma spectrum, deleting data abnormal sample points of the laser plasma spectrum, and establishing the deleted data sample set of the laser plasma spectrum;
and step s3, establishing a soil component quantitative analysis model, correcting and analyzing the data sample set of the laser plasma spectrum by adopting an internal standard method according to the soil nutrient element characteristic plasma spectral line with the determined wavelength, and establishing the soil component quantitative analysis model.
The method comprises the steps of determining the ratio of the spectral emission intensity of the soil at the wavelength of 744.23nm and 746.83nm, the soil phosphorus at the wavelength of 255.32nm and 253.56nm, the soil potassium at the wavelength of 766.49nm and 769.90nm to the emission intensity of an internal standard element, and establishing a soil component quantitative analysis model by using a binary linear regression method.
The laser spectrum analysis adopts high-energy laser pulses to directly hit the surface of a soil sample, high-intensity laser spots (plasma) are formed on the surface of an analysis material, elements to be detected in the sample are excited to a high-energy state, when the elements return to a ground state, respective characteristic spectra are emitted, and the spectra are detected to obtain the information of the types and the contents of all the elements in the soil. The method adopts laser beam to directly excite, can perform high-flux analysis on few soil samples, can realize the on-line detection and the in-situ detection of the soil, can realize the real-time detection and the rapid detection because the method can complete one-time measurement within several seconds, and has obvious advantages compared with other soil and fertilizer analysis technologies.
The specific working process of one embodiment of the invention can be completed as follows:
1. the soil element online detection device is hung at the rear part of a tractor, the current soil penetration depth (namely the distance from a soil surface C to be detected to a soil layer surface B) of the device is detected through an ultrasonic ranging sensor 16, then an embedded detection part 1 reaches the specified depth of the soil to be detected, an electric control mechanical device can be adopted to drive the embedded detection part 1 to penetrate the soil, and a smooth soil section to be detected is formed through the combined action of plow-shaped ditching and a scraper 14 in the advancing operation process of a farmland;
2. utilizing a laser emission and detection system to carry out laser emission and soil plasma attenuation spectrum data acquisition;
YAG laser is started, the emission laser wavelength is 1064nm, the pulse width is 8ns, the repetition frequency is 10Hz, and the maximum pulse energy is 200 mJ. The laser is transmitted into the optical path system in the shell 11 through the incident optical fiber 31, the laser is directly irradiated on the soil profile to be measured after being converged by the focusing lens 12, the soil to be measured reaches the breakdown threshold value under the irradiation of the instant high-energy laser beam, plasma is generated through local induction, after atomic spectrum signals generated in the plasma attenuation process are converged by the focusing lens 12, signal light spots are completely incident into the port of the collecting optical fiber 32, and the collecting optical fiber 32 is connected with the AOTF monochromator 221. Electrically tuned incident light wavelength scanning is achieved through acousto-optic interaction by controlling the frequency output of the direct frequency synthesizer 222. The upper computer sets the optimal sampling delay time and sampling gate width of the delay generator 224, the Nd-YAG laser triggers the delay generator 224 to work after emitting pulse laser, the detection controller 223 is driven to realize the acquisition and detection of spectral signals after sampling delay, the electric signals are sent to the upper computer after AD conversion, and the laser plasma spectrum of the soil to be detected is obtained through the processing and analysis of the upper computer. The speed of the tractor in field operation is set to be 5 kilometers per hour, the time for laser emission and soil plasma signal acquisition is 2 seconds, and therefore the sampling interval of nitrogen, phosphorus and potassium of soil is 2 meters, and the actual requirement of field soil fertilizer detection is completely met. (ii) a
3. The method comprises the steps of preprocessing the spectral data, deleting abnormal sample points, establishing a sample set, then correcting and analyzing the spectral data of the sample set by adopting an internal standard method, and establishing a mathematical model for quantitative analysis of nitrogen, phosphorus and potassium components of the soil.
According to the steps of the detection method, the collected soil plasma spectrum data is preprocessed, abnormal sample points are deleted, and a soil conventional nutrient prediction analysis model is established through binary linear regression according to the ratio of the spectrum emission intensity of the soil nitrogen element plasma spectrum characteristic spectral line at 744.23nm and 746.83nm, the soil phosphorus element at 255.32nm and 253.56nm, the soil potassium element at 766.49nm and 769.90nm to the emission intensity of the internal standard element;
4. and (3) collecting the attenuation spectrum data of the soil plasma for the unknown nutrient content sample of the soil, and then calculating the content of nutrient components in the soil by using the quantitative analysis model established in the step 3, thereby realizing the quantitative analysis of the nutrient content of the soil to be detected.
The laser plasma spectrum preprocessing method is mainly used for deleting abnormal sample points of spectrum data. Due to the fact that the spectral intensity fluctuates greatly and the reproducibility is poor due to factors such as laser energy fluctuation and sample nonuniformity, the prediction capability of the model is greatly reduced. Therefore, the sample spectrum intensity is deleted by a T test method with the confidence coefficient of 95%, and a sample set is established by the deleted spectrum data.
The internal standard method is a spectrum internal standard correction method: in this embodiment, the detection of nitrogen, phosphorus and potassium elements contained in soil is taken as an example for explanation. Preferably, the soil nitrogen element plasma characteristic spectral lines are at 744.23nm and 746.83nm (see figure 3), the soil phosphorus element plasma characteristic spectral lines are at 255.32nm and 253.56nm (see figure 4), and the soil potassium element plasma characteristic spectral lines are at 766.49nm and 769.90nm (see figure 5). In order to eliminate the serious matrix effect of spectral detection of soil nutrients, an element with an approximately unchanged content in soil is selected as an internal standard element, and internal standard processing is performed on the plasma spectral line intensity of the soil nutrient elements, for example, the plasma spectral line intensity at 255.32nm of the soil nitrogen elements is processed as follows:
wherein,is the spectral intensity internal standard value of the soil nitrogen element at 255.32nm,is the original intensity value of the spectrum at 255.32nm of soil nitrogen element, IrAnd obtaining the original intensity value of the characteristic spectral line of the soil internal standard element.
The soil component quantitative analysis model provided by the invention adopts a binary linear regression method to respectively establish a prediction analysis model of the nitrogen, phosphorus and potassium element content of the soil, so as to realize quantitative analysis of the nutrient content of the soil to be detected. Taking a soil nitrogen element content quantitative analysis model as an example:
wherein, YNIs the content of nitrogen element in the soil,andrespectively the spectral intensity internal standard values of soil nitrogen at 255.32nm and 253.56nm, a1、a2And b is a model calibration coefficient.
In this embodiment, the laser emission and detection system 2 may be composed of, for example, a Nd: YAG laser, an AOTF monochromator, a direct frequency synthesizer (DDS), a detection controller 223, a delay generator 224, and an upper computer. The Nd: YAG laser and AOTF monochromator 221 achieve laser delivery and collection of soil plasma spectra using an incident fiber 31 and a collection fiber 32, respectively. The direct frequency synthesizer 222(DDS) is directly connected to the AOTF monochromator 221, and the waveform output at the specified frequency through the DDS is radio-frequency driven to control the optical splitter of the AOTF monochromator 221 to change the wavelength of the monochromatic diffraction light. In order to effectively improve the signal-to-noise ratio and spectral line resolution of the soil plasma signal, the upper computer sends a command to control the delay generator 224, and selects proper sampling delay time to drive the spectrum detection controller 223, so that the detection of the discrete atomic spectrum of the soil to be detected is realized.
According to the invention, a complete laser emission and spectrum detection optical path system is integrated in the shell 11 of the soil-entering detection component 1, the soil-breaking edge 132 greatly reduces the soil-entering resistance of the device, and the plow-shaped furrow opener 131, the scraper 14 and the light screen 15 are designed to create a good working environment for efficiently and accurately completing the online detection of soil nutrients. The device simple structure installs and can gather field soil information on line fast behind agricultural machine, provides reliable data guarantee for field soil nutrient spatial distribution. The method is suitable for detecting nitrogen, phosphorus and potassium elements in the soil in a large range, can generate a soil nutrient space distribution map in a short time, and effectively guides subsequent accurate agricultural variable quantitative operation.
The invention provides a method and a device special for online detection of nitrogen, phosphorus and potassium elements in soil, aiming at the defects of high price, low representativeness and poor timeliness of farmland soil fertilizer detection technologies in the prior art, so as to solve the technical bottleneck of online rapid detection of soil fertilizers and realize online detection and in-situ detection of soil. In the method, the characteristic spectrum wavelength point of the nitrogen, phosphorus and potassium elements of the soil, which is suitable for realizing on-line rapid detection under the field working condition environment, is found, a systematic and scientific spectrum data processing method is provided, and reliable guarantee is provided for establishing an accurate quantitative analysis and prediction model of the content of the soil nutrients.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. The soil element on-line detection device is characterized by comprising an in-soil detection part and a laser emission and detection system, wherein the in-soil detection part is connected with the laser emission and detection system through an optical fiber, the in-soil detection part comprises a shell and a focusing lens arranged in the shell, the laser emission and detection system comprises a laser emission system, a laser acquisition system and a control system, the laser emission system is respectively connected with the focusing lens and the control system, the laser acquisition system is used for acquiring atomic spectrum signals generated in the plasma attenuation process of soil to be detected and transmitting the atomic spectrum signals to the control system, the control system processes and analyzes the atomic spectrum signals and compares and calculates the atomic spectrum signals with a soil component quantitative analysis model to obtain the content of element components in the soil to be detected, the soil-entering detection component further comprises a soil breaking mechanism, the soil breaking mechanism is arranged at the front end of the shell and used for reducing the working resistance of the shell advancing in soil, the soil breaking mechanism comprises a furrow opener, and the furrow opener is arranged at the bottom of the front end of the shell.
2. The soil element on-line detection device of claim 1, wherein the breaking mechanism further comprises a breaking edge disposed above the furrow opener and mounted on the housing.
3. The soil element on-line measuring device of claim 2, wherein the soil penetration measuring unit further comprises a scraper for leveling the measuring surface of the soil to be measured, the scraper being disposed behind the furrow opener and mounted at the bottom end of the housing.
4. The on-line soil element detection device as claimed in claim 3, wherein said penetration detection unit further comprises a light shielding plate for shielding the interference of extraneous light, said light shielding plate being installed at the bottom of said housing and disposed opposite to said scraper.
5. The soil element on-line detection device of claim 1, wherein the laser collection system comprises a monochromator connected to the focusing lens by an optical fiber, a direct frequency synthesizer connected to the monochromator, a detection controller connected to the monochromator and the control system, respectively, and a delay generator connected to the detection controller and the control system, respectively.
6. The soil element on-line detecting device as claimed in claim 5, wherein the penetration detecting unit further comprises a distance measuring sensor for detecting the penetration depth of the housing in real time, the distance measuring sensor being mounted on the upper end of the housing through a bracket and connected to the control system.
7. An on-line soil element detection method, which adopts the on-line soil element detection device as claimed in any one of claims 1 to 6, and is characterized by comprising the following steps:
a. detecting the soil penetration, so that the soil penetration detection part reaches the specified depth of the soil to be detected;
b. collecting soil plasma attenuation spectrum information, starting a laser emission and detection system by a control system, emitting laser by the laser emission system, transmitting the laser into a focusing lens through an optical fiber, converging light rays by the focusing lens, and then directly irradiating the light rays on a soil surface to be detected to obtain an atomic spectrum signal generated in the soil plasma attenuation process to be detected, transmitting the atomic spectrum signal to a laser collection system through the optical fiber, collecting the atomic spectrum signal by the laser collection system, and transmitting the atomic spectrum signal to the control system after AD conversion;
c. forming a laser plasma spectrum of the soil to be detected, and processing and analyzing the atomic spectrum signal by the control system to obtain the laser plasma spectrum of the soil to be detected;
d. and calculating the content of the element components in the soil to be detected, and calculating to obtain the content of the element components in the soil to be detected by utilizing the laser plasma spectrum of the soil to be detected and a soil component quantitative analysis model.
8. The method for on-line detection of soil elements as claimed in claim 7, wherein said soil composition quantitative analysis model is obtained by the steps of:
s1, obtaining the laser plasma spectrum of the soil to be detected by adopting the steps a-c;
s2, establishing a spectrum data sample set, preprocessing the laser plasma spectrum, deleting data abnormal sample points of the laser plasma spectrum, and establishing the deleted data sample set of the laser plasma spectrum;
s3, establishing a soil component quantitative analysis model, adopting an internal standard method to correct and analyze the data sample set of the laser plasma spectrum according to the soil nutrient element characteristic plasma spectral line with the determined wavelength, and establishing the soil component quantitative analysis model.
9. The method for on-line detection of soil elements according to claim 8, wherein in step s3, the ratio of the spectral emission intensity at the wavelengths of 744.23nm and 746.83nm for nitrogen elements in soil, 255.32nm and 253.56nm for phosphorus elements in soil, and 766.49nm and 769.90nm for potassium elements in soil to the emission intensity of internal standard elements is determined, and the soil composition quantitative analysis model is established by using a binary linear regression method.
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| CN104977181B (en) * | 2015-06-29 | 2017-12-01 | 中国科学院合肥物质科学研究院 | A kind of soil pattern collection pretreatment unit for soil constituent detection |
| CN106290309A (en) * | 2016-09-16 | 2017-01-04 | 天津大学 | Device is detected based on LIBS portable variable depth heavy metal content in soil |
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| CN109917107A (en) * | 2019-03-26 | 2019-06-21 | 中国农业科学院农业资源与农业区划研究所 | A kind of method of situ Rapid Determination Upland Red Soil potassium biological effectiveness |
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