CN103185708B - Online detection apparatus and method for soil elements - Google Patents

Abstract

An online detection device and method for soil elements, the device includes a soil penetration detection component and a laser emission and detection system, the soil penetration detection component is connected to the laser emission and detection system through an optical fiber, and the soil penetration detection component includes a housing and a device The focusing lens in the housing, the laser emission and detection system includes a laser emission system, a laser collection system and a control system, the laser emission system is connected with the focus lens and the control system respectively, and the laser collection system The system is respectively connected with the focusing lens and the control system. The method includes the following steps of soil entry detection, collecting soil plasma attenuation spectrum information, forming laser plasma spectrum of the soil to be tested and calculating the content of elemental components in the soil to be tested. The invention can realize the on-line and in-situ detection of soil in the field environment.

Description

A device and method for on-line detection of soil elements

technical field

The invention relates to a soil and fertilizer detection method and device, in particular to an online detection device and method for soil elements (especially nitrogen, phosphorus and potassium elements) for real-time, on-line rapid detection and analysis of field soil nutrients.

Background technique

Soil nutrient detection is the basic link of soil testing and formula fertilization, and is an important prerequisite and guarantee for fine fertilization management. It coordinates and analyzes important information such as nitrogen, phosphorus, potassium, organic matter, moisture, electrical conductivity, and pH value in the soil. The relationship between soil fertility, crop fertilizer requirements and fertilizer nutrient content, determine the scientific and reasonable type, quantity, time and method of fertilization. At present, a large number of large (medium) detection instruments are used in soil nutrient laboratory testing, such as high-efficiency gas chromatography, ion chromatography, continuous flow injection analyzer and spectrophotometer, etc., although multiple chemical components can be simultaneously analyzed. Measurement, the detection result is stable and the precision is high. However, in the process of practical application, the current method also has the following disadvantages: first, the detection price is relatively high. Limited by the cost of testing instruments, personnel training and chemical reagents, the cost of testing a single sample in a soil testing laboratory is currently around 100 to 200 yuan. It is difficult for most farmers to take the initiative to promote farmland when the profitability of output and input is not obvious. Nutrient testing. Second, the representativeness of the test results is poor. The per capita arable land area in China is less than 0.1hm ² , the production management is scattered, and the arable land fertility varies greatly. However, the field sampling unit proposed in "Technical Specifications for Soil Testing and Formulated Fertilization (Trial)" is 5~15hm ² . This method of soil sample collection may be applicable to some large-scale farms in northern my country, but it is not applicable to small-scale farmlands that are common in my country. Third, the timeliness of soil testing is poor. It takes at least 5 to 10 days from collecting soil samples, sending them to laboratories above the county level, and feeding back soil testing information after laboratory testing, to finally giving guidance on fertilization. In practical applications, farmers often get the laboratory analysis results, but miss the best time for crop fertilization. Therefore, this has become a bottleneck problem in the practice of precision agriculture to achieve cost-saving and efficiency-enhancing, fine variable fertilization. Compared with conventional laboratory analysis methods, soil online rapid measurement technology has better timeliness, lower cost, simpler testing equipment, and the testing accuracy does not need to be too high as long as it meets the application requirements. With the popularization and application of soil testing and formula fertilization nationwide, it is urgent to promote the research on fast and reliable online testing methods for soil and fertilizer.

Soil is a complex multi-phase aggregate, which is affected by multiple factors. The online rapid detection technology of soil nutrients has always been a technical bottleneck that is difficult to break through in the acquisition of front-end information for precision agriculture. And the development of special testing equipment is of great practical significance for efficiently and accurately understanding the spatial distribution of soil nutrients in farmland, reducing the use of land chemical 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. .

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and device for detecting elements such as nitrogen, phosphorus and potassium in the field environment, so as to solve the technical bottleneck of online rapid detection of soil and fertilizer, and realize online and in-situ detection of soil.

In order to achieve the above object, the present invention provides an online detection device for soil elements, which includes a soil penetration detection component and a laser emission and detection system, the soil penetration detection component is connected to the laser emission and detection system through an optical fiber, and the soil penetration The detection component includes a housing and a focusing lens arranged in the housing, and the laser emitting and detecting system includes a laser emitting system, a laser acquisition system and a control system, and the laser emitting system is connected with the focusing lens and the control system respectively. System connection, the laser acquisition system is connected with the focusing lens and the control system respectively, the laser acquisition system is used to collect the atomic spectrum signal generated in the soil plasma decay process to be measured and transmit it to the control system, the The control system processes and analyzes the atomic spectrum signal and compares it with the soil component quantitative analysis model to calculate the content of element components in the soil to be tested.

The above-mentioned soil element online detection device, wherein, the soil penetration detection part further includes a soil breaking mechanism, the soil breaking mechanism is arranged at the front end of the casing, and is used to reduce the working resistance of the casing moving forward in the soil, so The ground-breaking mechanism includes a plow-type furrow opener, and the plow-type furrow opener is arranged at the bottom of the front end of the housing.

In the above online detection device for soil elements, the soil breaking mechanism further includes a soil breaking blade, and the soil breaking blade is arranged above the plow opener and mounted on the housing.

The above-mentioned soil element online detection device, wherein, the soil-entry detection part further includes a scraper for leveling the detection surface of the soil to be tested, and the scraper is arranged behind the plow opener and installed on the bottom of the housing.

The above-mentioned soil element online detection device, wherein, the soil penetration detection part further includes a shading plate for shielding the interference of external stray light, and the shading plate is installed at the bottom of the housing and arranged relative to the scraper .

The above-mentioned online detection device for soil elements, wherein the laser acquisition system includes a monochromator, a direct frequency synthesizer, a detection controller and a delay generator, the monochromator is connected to the focusing lens through an optical fiber, and the 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 connected with the detection controller and the control system respectively .

The above-mentioned soil element online detection device, wherein, the soil penetration detection part further includes a distance measuring sensor for real-time detection of the soil penetration depth of the casing, and the distance measurement sensor is installed on the upper end of the casing through a bracket And connected with the control system.

In order to better achieve the above object, the present invention also provides a method for online detection of soil elements, using the above-mentioned online detection device for soil elements, which includes the following steps:

a. Soil penetration detection, so that the soil penetration detection component reaches the specified depth of the soil to be tested;

b. Collect soil plasma attenuation spectrum information, the control system starts the laser emission and detection system, the laser emission system emits laser light and transmits it to the focusing lens through the optical fiber, and directly irradiates it after the light is converged by the focusing lens On the surface of the soil to be measured, the atomic spectrum signal generated during the plasma attenuation process of the soil to be measured is obtained and transmitted to the laser collection system through the optical fiber, and the laser collection system collects the atomic spectrum signal and transmits it after AD conversion to said control system;

c. Forming the laser plasma spectrum of the soil to be measured, the control system processes and analyzes the atomic spectrum signal to obtain the laser plasma spectrum of the soil to be measured;

d. Calculate the content of elemental components in the soil to be tested, and use the laser plasma spectrum of the soil to be tested and the quantitative analysis model of soil components to calculate the content of elemental components in the soil to be tested.

The above-mentioned method for online detection of soil elements, wherein the quantitative analysis model of the soil components is obtained by the following steps:

s1. Obtain the laser plasma spectrum of the soil to be tested by using the steps described in a to c;

s2. Establishing a spectral data sample set, preprocessing the laser plasma spectrum, deleting abnormal data sample points of the laser plasma spectrum, and establishing a deleted data sample set of the laser plasma spectrum;

s3. Establishing a soil component quantitative analysis model, using the internal standard method to correct and analyze the data sample set of the laser plasma spectrum according to the characteristic plasma spectral line of the soil nutrient elements at a determined wavelength, and establishing the soil component quantitative analysis model.

The above-mentioned soil element online detection method, wherein, in step s3, it is determined that the soil nitrogen element is 744.23nm and 746.83nm, the soil phosphorus element is 255.32nm and 253.56nm, and the soil potassium element is the spectral emission at the wavelength of 766.49nm and 769.90nm Intensity and internal standard element emission intensity ratio, using binary linear regression method to establish the quantitative analysis model of the soil components.

The technical effect of the present invention is: the present invention overcomes the shortcomings of traditional farmland soil and fertilizer detection technology such as high price, low representativeness, and poor timeliness, solves the technical bottleneck of online rapid detection of soil and fertilizer, and realizes "online" and "in situ" of soil detection. The device of the present invention can be directly hung behind a tractor to realize large-scale online detection of elements such as soil nitrogen, phosphorus, and potassium, and generate a spatial distribution map of soil nutrients in a relatively short period of time, effectively guiding subsequent precision agricultural variable operations.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 is a schematic structural diagram of a detection device according to an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a soil penetration detection component according to an embodiment of the present invention;

Fig. 3 is soil nitrogen element plasma spectrum characteristic line;

Fig. 4 is soil phosphorus element plasma spectrum characteristic line;

Fig. 5 is soil potassium element plasma spectrum characteristic line;

6 is a flow chart of a detection method according to an embodiment of the present invention;

Fig. 7 is a flowchart of establishing a quantitative analysis model of soil components according to an embodiment of the present invention.

Among them, reference signs

1 Soil entry detection parts

11 Housing

12 focus lens

13 Ground-breaking institutions

131 Openers

132 Earth Breaker

14 scraper

15 visor

16 distance sensor

17 bracket

18 lens mount

2 Laser emission and detection system

21 Laser emission system

22 Laser acquisition system

221 Monochromator

222 direct frequency synthesizer

223 detection controller

224 delay generator

23 control system

3 optical fiber

31 incident fiber

32 collection fiber

A detection point

B Soil layer surface

C Soil surface to be tested

a~d, s1~s3 steps

Detailed ways

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

Referring to FIG. 1 , FIG. 1 is a schematic structural diagram of a detection device according to an embodiment of the present invention. The soil element on-line detection device of the present invention comprises a soil penetration detection component 1 and a laser emission and detection system 2, the soil penetration detection component 1 is connected to the laser emission and detection system 2 through an optical fiber 3, and the soil penetration detection component 1 includes a shell body 11 and the focusing lens 12 arranged in the housing 11, the housing is preferably made of steel, the laser emission and detection system 2 includes a laser emission system 21, a laser acquisition system 22 and a control system 23, the laser emission system 21 are respectively connected with the focus lens 12 and the control system 23, the laser collection system 22 is connected with the focus lens 12 and the control system 23 respectively, and the laser collection system 22 is used to collect the soil plasma to be measured The atomic spectrum signal generated during the attenuation process is transmitted to the control system 23, and the control system 23 processes and analyzes the atomic spectrum signal and compares it with the soil component quantitative analysis model to calculate the content of element components in the soil to be tested. In this embodiment, the optical fiber 3 includes an incident optical fiber 31 and a collection optical fiber 32, preferably two focusing lenses 12, and 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 The focal points of the two focusing lenses 12 are located on the surface C of the soil to be measured and converge on the same detection point A. The upper end of the lens mount 18 is connected with incident optical fiber 31 and collecting optical fiber 32 respectively, adjust the positions of incident optical fiber 31 and collecting optical fiber 32 and fix them respectively, so that the ports of incident optical fiber 31 and collecting optical fiber 32 are located at the other side of two focusing lenses 12 respectively. focus.

Referring to FIG. 2 , FIG. 2 is a schematic structural diagram of a soil penetration detection component according to an embodiment of the present invention. In this embodiment, the soil-entry detection component 1 further includes a soil-breaking mechanism 13, which is arranged at the front end of the housing 11 to reduce the working resistance of the housing 11 advancing in the soil. The ground breaking mechanism 13 includes a furrow opener 131 , preferably a plow-shaped furrow opener, and the plow-shaped furrow opener 131 is arranged at the bottom of the front end of the housing 11 . The soil breaking mechanism 13 also includes a soil breaking blade 132, and the soil breaking blade 132 is arranged above the ditch opener 131 and installed on the housing 11, or between the ditch opener 131 and the housing 11. A rib is arranged between them, and the soil-breaking blade 132 is arranged on the front end of the rib, and can also be integrated with the rib. In this embodiment, the soil penetration detection component 1 may also include a scraper 14 for leveling the surface C of the soil to be tested. The scraper 14 is arranged behind the opener 131 and installed on the The bottom end of the housing 11. The soil-entry detection part 1 can also include a shading plate 15, which is used to shield the interference of stray light from the outside, and further improves the accuracy of detection. The shading plate 15 is installed on the bottom of the housing 11 and relatively Plate 14 is provided.

In this embodiment, the laser acquisition system 22 includes a monochromator 221, a direct frequency synthesizer 222, a detection controller 223 and a delay generator 224, and the monochromator 221 is connected to the focusing lens 12 through an optical fiber 3 , the direct frequency synthesizer 222 is connected with the monochromator 221, the detection controller 223 is connected with the monochromator 221 and the control system 23 respectively, and the delay generator 224 is respectively connected with the The detection controller 223 is connected to the control system 23 . In order to realize the "in situ" detection of soil nutrients at the same soil depth, the soil penetration detection part 1 may also include a ranging sensor 16 for real-time detection of the soil penetration depth of the housing 11, which can be driven by corresponding electronically controlled The mechanical unit maintains a uniform depth of soil nutrient detection. The distance measuring sensor 16 can be installed on 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 present invention. The soil element online detection method of the present invention comprises the following steps:

Step a, soil penetration detection, making the soil penetration detection component 1 reach the specified depth of the soil to be tested;

Step b, collecting soil plasma attenuation spectrum information, the control system 23 starts the laser emission and detection system 2, the laser emission system 21 emits laser light and transmits it to the focusing lens 12 through the optical fiber 3, and the focusing The lens 12 condenses the light and directly irradiates the surface C of the soil to be measured to obtain the atomic spectrum signal generated during the plasma attenuation process of the soil to be measured, and transmits it to the laser collection system 22 through the optical fiber 3, and the laser collection system 22 collects The atomic spectrum signal is transmitted to the control system 23 after AD conversion;

Step c, forming the laser plasma spectrum of the soil to be tested, the control system 23 processes and analyzes the atomic spectrum signal to obtain the laser plasma spectrum of the soil to be tested;

Step d, calculating the content of elemental components in the soil to be tested, using the laser plasma spectrum of the soil to be tested and the quantitative analysis model of soil components to calculate the content of elemental components in the soil to be tested.

Referring to Fig. 7, Fig. 7 is a flowchart of establishing a quantitative analysis model of soil components according to an embodiment of the present invention. Described soil component quantitative analysis model can adopt following steps to obtain:

Step s1, adopting the steps described in steps a to c to obtain the laser plasma spectrum of the soil to be tested;

Step s2, establishing a spectral data sample set, performing preprocessing on the laser plasma spectrum, deleting abnormal data sample points of the laser plasma spectrum, and establishing a deleted data sample set of the laser plasma spectrum;

Step s3, establishing a soil component quantitative analysis model, and using the internal standard method to calibrate and analyze the data sample set of the laser plasma spectrum according to the characteristic plasma spectral line of the soil nutrient elements at a determined wavelength, and establish the soil component quantitative analysis model.

Wherein, it is determined that the soil nitrogen element is 744.23nm and 746.83nm, the soil phosphorus element is 255.32nm and 253.56nm, and the soil potassium element is the ratio of the spectral emission intensity at the wavelength of 766.49nm and 769.90nm and the emission intensity of the internal standard element, using two A linear regression method was used to establish the quantitative analysis model of the soil components.

Laser spectroscopy uses high-energy laser pulses to directly hit the surface of the soil sample, forming a high-intensity laser spot (plasma) on the surface of the analyzed material, which excites the elements to be measured in the sample to a high-energy state, and when they return to the ground state, they emit their respective The characteristic spectrum, the detection of this spectrum can simultaneously obtain all the element types and content information in the soil. This method uses laser beams to directly excite, and few soil samples can be used for high-throughput analysis, which can realize "on-line" and "in-situ" detection of soil, and because this method can usually complete a measurement within a few seconds, so It can realize "real-time" and "rapid" detection, and has obvious advantages over other soil and fertilizer analysis technologies.

The concrete work process of an embodiment of the present invention can be finished as follows:

1, the soil element on-line detection device of the present invention is hung on the tractor rear portion, at first by the ultrasonic ranging sensor 16 detection device current depth of penetration (i.e. the distance from the soil surface to be measured C to the surface of the soil layer B), and then the penetration detection part 1. When the specified depth of the soil to be tested is reached, the soil entry detection part 1 can be driven into the soil by an electronically controlled mechanical device. During the forward operation of the farmland, a flat soil section to be tested is formed through the joint action of the plow type ditch and the scraper 14;

2. Use the laser emission and detection system to collect laser emission and soil plasma attenuation spectrum data;

Start the Nd:YAG laser, the emission wavelength is 1064nm, the pulse width is 8ns, the repetition frequency is 10Hz, and the maximum pulse energy is 200mJ. The laser light enters the optical path system in the housing 11 through the incident optical fiber 31, and after the light is converged by the focusing lens 12, it is directly irradiated on the section of the soil to be tested. The soil to be tested reaches the breakdown threshold under the instantaneous high-energy laser beam irradiation, and locally induces the generation of plasma. After the atomic spectrum signal generated during the plasma attenuation process is converged by the focusing lens 12, the signal spot is completely incident on the port of the collection fiber 32, and the collection fiber 32 is connected to the AOTF monochromator 221. By controlling the frequency output of the direct frequency synthesizer 222, through the acousto-optic interaction, the electrical tuning of the incident light wavelength scanning is realized. The optimal sampling delay time and sampling gate width of the delay generator 224 are set by the host computer, and the delay generator 224 is triggered after the Nd:YAG laser emits pulsed laser light, and the detection controller 223 is driven to realize the spectral signal after the sampling delay. The electrical signal is sent to the host computer after AD conversion, and the laser plasma spectrum of the soil to be tested is obtained through the processing and analysis of the host computer. The speed of the tractor in the field is set to 5 km/h, and the laser emission and soil plasma signal acquisition takes 2 seconds. Therefore, the sampling distance of soil nitrogen, phosphorus and potassium is 2 meters, which fully meets the actual needs of field soil and fertilizer detection. ;

3. Through the preprocessing of the spectral data, delete abnormal sample points, establish a sample set, and then use the internal standard method to correct and analyze the spectral data of the sample set, and establish a mathematical model for the quantitative analysis of soil nitrogen, phosphorus, and potassium components.

The collected soil plasma spectrum data is in accordance with the detection method steps of the present invention, and through data preprocessing, abnormal sample points are deleted. According to the soil nitrogen element plasma spectrum characteristic line at 744.23nm and 746.83nm, soil phosphorus element 255.32nm and 253.56nm, soil The ratio of the spectral emission intensity of the potassium element at 766.49nm and 769.90nm to the emission intensity of the internal standard element is used to establish a soil conventional nutrient prediction and analysis model through binary linear regression;

4. For samples with unknown nutrient content in the soil, collect soil plasma attenuation spectrum data, and then use the quantitative analysis model established in the above 3 to calculate the content of nutrient components in the soil, and then realize the quantitative analysis of the nutrient content of the soil to be measured.

Wherein, the method for preprocessing the laser plasma spectrum is mainly used to delete abnormal sample points of the spectral data. Due to factors such as laser energy fluctuations and sample inhomogeneity, the spectral intensity fluctuates greatly and the reproducibility is poor, which greatly reduces the predictive ability of the model. For this reason, the T-test method with a confidence level of 95% was used to delete the spectral intensity of the samples, and the spectral data after deletion were used to establish a sample set.

The internal standard method is the spectral internal standard correction method: In this embodiment, the detection of nitrogen, phosphorus and potassium elements contained in soil is taken as an example for illustration. The preferred soil nitrogen element plasma spectrum characteristic line is at 744.23nm and 746.83nm (see Figure 3), the soil phosphorus element plasma spectrum characteristic line is at 255.32nm and 253.56nm (see Figure 4), and the soil potassium element plasma spectrum characteristic line at 766.49nm and 769.90nm (see Figure 5). In order to eliminate the serious matrix effect of soil nutrient spectrum detection, an element with roughly constant content in the soil is selected as an internal standard element, and the plasma line intensity of soil nutrient elements is treated as an internal standard, such as the plasma spectrum of soil nitrogen at 255.32nm Line strengths are handled as follows:

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 255.32</span>}\mathrm{<span\; class="notranslate">\; nm</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; lg</span>}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 255.32</span>}\mathrm{<span\; class="notranslate">\; nm</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; r</span>}}}$

in, is the internal standard value of the spectral intensity of soil nitrogen at 255.32nm, is the original intensity value of the soil nitrogen spectrum at 255.32nm, and ^Ir is the original intensity value of the characteristic spectral line of the soil internal standard element.

The soil component quantitative analysis model of the present invention adopts a binary linear regression method to respectively establish a predictive analysis model for the content of nitrogen, phosphorus and potassium elements in the soil, so as to realize the quantitative analysis of the nutrient content of the soil to be measured. Take the quantitative analysis model of soil nitrogen content as an example:

$\mathrm{<span\; class="notranslate">\; lg</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 255.32</span>}\mathrm{<span\; class="notranslate">\; nm</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 253.56</span>}\mathrm{<span\; class="notranslate">\; nm</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; b</span>}$

Among them, Y ^N is the content of nitrogen in the soil, and are the internal standard values of the spectral intensity of soil nitrogen at 255.32nm and 253.56nm respectively, and a ₁ , a ₂ and b are model calibration coefficients.

In this embodiment, the laser emission and detection system 2 can 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 a host computer. The Nd:YAG laser and the AOTF monochromator 221 use the incident optical fiber 31 and the collection optical fiber 32 to realize laser transmission and soil plasma spectrum collection respectively. The direct frequency synthesizer 222 (DDS) is directly connected to the AOTF monochromator 221, and the waveform output of the specified frequency through the DDS is driven by radio frequency to control the spectroscopic device of the AOTF monochromator 221 to change the wavelength of the monochromatic diffracted light. In order to effectively improve the signal-to-noise ratio and spectral line resolution of the soil plasma signal, the host computer sends commands to control the delay generator 224, selects an appropriate sampling delay time to drive the spectrum detection controller 223, and realizes the detection of the discrete atomic spectrum of the soil to be measured.

The present invention integrates a complete laser emission and spectrum detection optical path system in the casing 11 of the soil entry detection component 1, the soil breaking blade 132 greatly reduces the resistance of the device to entry into the soil, and the design of the plow opener 131, the scraper 14 and the light shield 15 Create a good working environment for efficient and accurate online soil nutrient detection. The device has a simple structure and can quickly collect field soil information online after being installed on agricultural machinery, providing reliable data guarantee for the spatial distribution of farmland soil nutrients. The invention is suitable for detecting nitrogen, phosphorus and potassium elements in a large range of soil, and can generate a spatial distribution map of soil nutrients in a short period of time to effectively guide subsequent precision agricultural variable operations.

Aiming at the deficiencies of the prior art farmland soil and fertilizer detection technology, such as high price, low representativeness, and poor timeliness, a method and device dedicated to the on-line detection of soil nitrogen, phosphorus, and potassium elements are proposed to solve the technical bottleneck of on-line rapid detection of soil and fertilizer, and realize Soil "on-line" and "in-situ" testing. In this method, the characteristic spectral wavelength points of soil nitrogen, phosphorus and potassium elements suitable for on-line rapid detection under field conditions were found, and a systematic and scientific spectral data processing method was proposed to establish an accurate quantitative analysis and prediction model for soil nutrient content. Provide reliable protection.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (9)

1. An online detection device for soil elements, characterized in that it includes a soil-entry detection component and a laser emission and detection system, the soil-entry detection component is connected with the laser emission and detection system through an optical fiber, and the soil-entry detection component includes a housing and a focusing lens arranged in the housing, the laser emitting and detecting system includes a laser emitting system, a laser collecting system and a control system, the laser emitting system is respectively connected with the focusing lens and the control system, the The laser acquisition system is respectively connected with the focusing lens and the control system. The laser acquisition system is used to collect the atomic spectrum signal generated during the plasma decay process of the soil to be measured and transmit it to the control system. The control system processes and analyzes The atomic spectrum signal is compared with the soil composition quantitative analysis model to calculate the content of the element composition in the soil to be tested, and the soil penetration detection part also includes a soil breaking mechanism, which is arranged at the front end of the housing for reducing To reduce the working resistance of the casing moving forward in the soil, the soil breaking mechanism includes a ditch opener, and the ditch opener is arranged at the bottom of the front end of the casing. 2 . The online detection device for soil elements according to claim 1 , wherein the soil-breaking mechanism further comprises a soil-breaking blade, and the soil-breaking blade is arranged above the trench opener and mounted on the housing. 3 . 3. The soil element on-line detection device according to claim 2, wherein the soil-entry detection part also includes a scraper for leveling the detection surface of the soil to be tested, and the scraper is arranged on the ditch to the rear of the device and mounted on the bottom end of the housing. 4. The soil element on-line detection device according to claim 3, wherein the soil penetration detection part also includes a shading plate for shielding the interference of external stray light, and the shading plate is installed on the side of the housing. bottom and set relative to the scraper. 5. The soil element on-line detection device as claimed in claim 1, wherein the laser acquisition system comprises a monochromator, a direct frequency synthesizer, a detection controller and a delay generator, and the monochromator passes through an optical fiber It is connected with the focusing lens, 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 The detection controller is connected with the control system. 6. The soil element on-line detection device as claimed in claim 5, wherein the soil penetration detection part further comprises a ranging sensor for real-time detection of the penetration depth of the housing, and the ranging sensor passes through a The bracket is installed on the upper end of the housing and connected with the control system. 7. A method for online detection of soil elements, using the online detection device for soil elements according to any one of claims 1 to 6, characterized in that it comprises the following steps: a. Soil penetration detection, so that the soil penetration detection component reaches the specified depth of the soil to be tested; b. Collect soil plasma attenuation spectrum information, the control system starts the laser emission and detection system, the laser emission system emits laser light and transmits it to the focusing lens through the optical fiber, and directly irradiates it after the light is converged by the focusing lens On the surface of the soil to be measured, the atomic spectrum signal generated during the plasma attenuation process of the soil to be measured is obtained and transmitted to the laser collection system through the optical fiber, and the laser collection system collects the atomic spectrum signal and transmits it after AD conversion to said control system; c. Forming the laser plasma spectrum of the soil to be measured, the control system processes and analyzes the atomic spectrum signal to obtain the laser plasma spectrum of the soil to be measured; d. Calculate the content of elemental components in the soil to be tested, and use the laser plasma spectrum of the soil to be tested and the quantitative analysis model of soil components to calculate the content of elemental components in the soil to be tested. 8. soil element online detection method as claimed in claim 7, is characterized in that, described soil composition quantitative analysis model adopts the following steps to obtain: s1. Obtain the laser plasma spectrum of the soil to be tested by using the steps described in a to c; s2. Establishing a spectral data sample set, preprocessing the laser plasma spectrum, deleting abnormal data sample points of the laser plasma spectrum, and establishing a deleted data sample set of the laser plasma spectrum; s3. Establishing a soil component quantitative analysis model, using the internal standard method to correct and analyze the data sample set of the laser plasma spectrum according to the characteristic plasma spectral line of the soil nutrient elements at a determined wavelength, and establishing the soil component quantitative analysis model. 9. The soil element online detection method as claimed in claim 8, characterized in that, in step s3, it is determined that the soil nitrogen element is 744.23nm and 746.83nm, the soil phosphorus element is 255.32nm and 253.56nm, and the soil potassium element is 766.49nm and the ratio of the spectral emission intensity at the wavelength of 769.90nm and the emission intensity of the internal standard element, and the quantitative analysis model of the soil components is established by using a binary linear regression method.