Method for analyzing components of soil

Abstract

To provide a soil component analysis method capable of performing work in a field or the like.SOLUTION: The component analysis method of the soil includes a process for exposing a soil cross section by excavating the soil, a process for photographing the soil surface of the soil cross section by using the portable terminal having a camera function, and a process for determining a color on the basis of the photographed image to specify the soil component.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for analyzing soil components to evaluate the productivity and quality of agricultural soil. [Background technology]

[0002] In recent years, the introduction of field crops from paddy fields has led to the widespread adoption of vegetable crops such as onions and cabbage, raising the importance of soil fertility and fertilization management. Meanwhile, recent heavy rains have caused damage to agricultural production and the collapse of farmland foundations in highly erodible fields. While restoration work has been widely carried out, the current situation of inadequate management of soil chemistry in restored farmland has become apparent. Understanding soil physicochemical properties is essential for cultivation and soil management in these fields, and soil diagnostics have advanced. While advanced regions utilize soil analysis in agricultural planning, many regions only conduct it after problems have occurred, and the implementation rate remains low. In addition, while soil analysis techniques have traditionally been performed by experts, in recent years, regional extension centers and other training institutions have been unable to perform soil analysis. Therefore, there is a need for an inexpensive, simple, and rapid analytical method for determining soil physicochemical properties that can be used by agricultural instructors and technicians with no prior experience, as well as by farmers themselves, even without the necessary facilities and equipment.

[0003] Specific examples of such soil and water analysis methods are given in Patent Documents 1 and 2 and Non-Patent Documents 1 and 2. Conventional techniques include the general soil analysis method described in Non-Patent Document 1 and the simple soil analysis method described in Non-Patent Document 2, but both require the following procedure. 1) After preparing the test soil and measuring a certain weight, 2) prepare a test solution by extracting the components with a certain volume of extraction solution or by decomposing them with acid and dissolving them, 3) dilute or concentrate the test solution with a solvent such as water to the appropriate component concentration, and prepare a test solution that has been given a specific color so that the component concentration can be detected. 4) The components in the test solution are detected using an analytical device such as a spectrophotometer, and the concentration is measured. 5) The amount of the component per unit weight of soil (hereinafter referred to as the component amount) is calculated from the concentration, the volume of test solution, the volume of test solution, the dilution or concentration ratio of the solvent, and the volume of test soil. Using this component amount, the amount of the component present in agricultural soil is evaluated, taking into account the approximate specific gravity and depth of general soil. Patent Document 1 proposes a system that converts the color information of a measured object into RGB numerical information and compares it with a calibration curve created based on the RGB numerical information of samples with known concentrations to measure the concentration as chemical information correlated with the color information of the measured object, but it does not propose a method that targets soil itself or carbon. Furthermore, it is necessary to set a calibration curve that corresponds to the transmittance of the spectral wavelength of the color-developing solution of the measured component, the luminous intensity level of the transmitted light, and the concentration, each time, which requires a measurement method that requires a dedicated laboratory. In Patent Document 2, a measurement method is used in which the volume is measured by the increase caused by putting a lump of soil into water in a measuring cylinder. However, since the gas phase, which is the part of the soil volume where air exists, is not measured, the true specific gravity of the soil can be measured, but it is corrected by multiplying it by a correction coefficient. Furthermore, the method for calculating the correction coefficient is unknown, and the volume is evaluated as being small, making it impossible to accurately evaluate the provisional specific gravity.

[0004] Below are listed the main problems in the process of analyzing soil components. <Sample weighing> When measuring the mass, raw soil is often adjusted to air-dried soil, but this makes it difficult to work in fields, etc. <When calculating> The amount of fertilizer to be applied is calculated based on analytical values ​​as well as empirical dry density and plowed soil thickness, so the accuracy of the final results is not as high as that of soil analysis. <When applying fertilizer> The accuracy of the fertilizer amount adjustment on the agricultural machinery side cannot be guaranteed to be as high as the analysis results. <During analysis> The process of extracting components from soil and turning them into test liquid is mostly done in laboratories. Most analytical methods use liquids, which are difficult to handle and dispose of. - There are few proposals for direct soil analysis methods that can provide stable measurement values. <Analysis based on soil color> Patent Document 3 discloses a soil organic component measuring device that calculates the amount of organic components in soil based on soil color components. The device includes a container for storing a predetermined amount of soil, an imaging unit for capturing an image of the soil surface stored in the container, and a calculation unit for detecting the brightness of the soil surface based on the image captured by the imaging unit and calculating the amount of organic components in the soil based on the detected brightness. While the device requires sufficient wetting of air-dried soil to capture the image, adding water alone is insufficient to suppress light scattering or stabilize the color development on the sample surface. A preliminary step involves air-drying the collected soil, but this step is difficult to perform in the field. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-80990 A (Concentration measurement system) [Patent Document 2] Patent No. 5343163 (Soil analysis system and soil analysis program) [Patent Document 3] JP 2005-017115 A (Soil organic component estimation device) [Non-patent literature]

[0006] [Non-Patent Document 1] Analytical methods for soil, water quality and plant tissue for soil function monitoring surveys, edited by the Japan Soil Association, March 2001, pp. 33-99. [Non-patent document 2] Analytical Methods for Soil and Crop Nutrition Diagnosis 2012, compiled by the Hokkaido Research Organization, Agricultural Research Headquarters, August 2012, https: / / www.hro.or.jp / list / agricultural / center / bunseki2012 / index.html, full text, "Nitrate Nitrogen (Simple Method Using RQ Flex)" https: / / www.hro.or.jp / list / agricultural / center / bunseki2012 / 4.pdf. Summary of the Invention [Problem to be solved by the invention]

[0007] The challenge with soil component analysis methods is that they are primarily performed indoors, requiring time-consuming and laborious work by specialists with scientific knowledge. Components are extracted, adjusted, and colored using reagents, etc., from a fixed weight of dried soil sample, and the amount of each component per weight is then measured using a spectrophotometer, atomic absorption photometer, or various other measuring devices. As a result, they are not suitable for on-site analysis in fields, etc. On the other hand, the accuracy of soil component analysis, which is time-consuming and laborious, is not balanced with the precision of mechanical methods used to adjust fertilizer amounts. While technical proposals for on-site analysis methods have been made, they are not adequately applicable to many components.

[0008] In view of the above-mentioned current situation, an object of the present invention is to provide a method for analyzing soil components that can be used in fields or the like and that can solve the problems of the prior art. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, one embodiment of the present invention has the following configuration. The method for analyzing soil components includes the steps of excavating the soil to expose a soil cross-section, photographing the soil surface of the soil cross-section using the mobile terminal having a camera function, and determining the color and identifying the soil components based on the photographed image. [Effects of the Invention]

[0010] The method and equipment for extracting soil components and analyzing component concentrations of the present invention for evaluating the productivity and quality of agricultural soil is an analytical technique that can be used by farmers themselves to grasp the physical and chemical properties of the soil on-site at low cost, simply, and quickly.It is a field evaluation technology that can easily grasp the productivity of a field, its unevenness, and the results of improvement when farmers are unsure of what to do, such as whether or not to apply top dressing due to poor growth that could not be addressed by prior soil analysis, changing planting or cultivated land, and confirming the need for soil improvement and the effects of that improvement, and it will enable the development of technology that can contribute to strengthening the production of high-quality agricultural crops. [Brief explanation of the drawings]

[0011] [Figure 1] Figure 1 is a diagram explaining a method for analyzing soil components and a method for obtaining soil sample collection information, such as location information of the collection site, soil type, dry density, and other physicochemical information, when using an apparatus that realizes part of the method. [Figure 2] FIG. 2 is a diagram illustrating a method for adjusting the amount of soil sample and the extract using soil physicochemical information when a method for analyzing soil components and an apparatus that partially implements the method are used. [Figure 3] This figure explains a method for adjusting soil, i.e., a method for stabilizing soil color, in which the soil color is kept constant while suppressing light scattering from the soil sample when photographing the soil sample, when using a method for analyzing soil components and an instrument that realizes part of the method. [Figure 4] FIG. 4 is a diagram illustrating a method for photographing a soil sample when using a method for analyzing soil components and an apparatus that partially implements the method. [Figure 5] Figure 5 is a diagram explaining an adjustment method for suppressing light scattering in the soil of a cross section and an imaging method for directly photographing and analyzing soil without collecting soil samples outdoors when using a method for analyzing soil components and an instrument that realizes part of the method. [Figure 6]Figure 6 is a diagram illustrating a method for analyzing soil components and an apparatus that realizes part of the method, in which soil is analyzed without collecting soil samples outdoors. The method involves using an alkaline solution to dissolve the humus in the soil, coloring it onto filter paper, and then using this as a sample to photograph the color of the humus in the soil. [Figure 7] FIG. 7 is a diagram illustrating a method for analyzing soil components and a method for measuring the components by extracting components from a soil sample using an extracting liquid, diluting the components, and coloring the components, when using an apparatus that realizes part of the method. [Figure 8] FIG. 8 is a diagram illustrating a measurement method by acquiring images of a prepared soil sample or an extract when a method for analyzing soil components and an apparatus for implementing a part of the method are used. [Figure 9] FIG. 9 is a diagram illustrating a method for measuring component concentrations by acquiring images of prepared soil samples or extracts and comparing them with sample colors when using a method for analyzing soil components and an apparatus that partially implements the method. [Figure 10] FIG. 10 is a diagram illustrating a method for measuring component concentrations by acquiring images of prepared soil samples or extracts and comparing them with sample colors when using a method for analyzing soil components and an apparatus that implements part of the method. [Figure 11] FIG. 11 is a diagram for explaining a method for creating a standard concentration table showing component concentrations corresponding to sample colors when using a method for analyzing soil components and an apparatus that partially implements the method. [Figure 12] Figure 12 is a diagram illustrating an example of a method for stabilizing soil color by measuring the reflectance at each wavelength of a soil sample that has been compressed and then adjusted to saturated or dry conditions, when using a method for analyzing soil components and an instrument that implements part of the method. [Figure 13] FIG. 13 shows an example in which carbon, a component of soil, was measured using an image of an extracting and coloring solution for the soil component when a method for analyzing soil components and an apparatus for implementing a part of the method were used. [Figure 14]FIG. 14 shows an example of measuring the components of soil by image measurement of an extracting and coloring solution for the components, when a method for analyzing the components of soil and an apparatus for implementing a part of the method are used. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] Referring to FIG. 1, the following describes a method for collecting soil samples and a method for acquiring physicochemical information about the soil, such as the type of soil and dry density, in addition to location information about the collection site, when using a method for analyzing soil components according to the present invention and an apparatus that realizes part of the method. The device in question may be a mobile terminal A such as a smartphone or tablet that has a camera function, a location information acquisition function, and a code reading function. The location information acquisition function is realized using a satellite positioning system such as GPS. When a soil sample S is collected from farmland into a bag, case, or other sample container 20 bearing a two-dimensional code, particularly a QR code (registered trademark) Q, which contains at least an identification number as information, location information P of the collection point can also be obtained by photographing the sample container 20 bearing the QR code (registered trademark) Q with a camera C attached to a mobile terminal A. The sample container 20 containing the collected soil may also be referred to as a soil sample container 20. The one-dimensional or two-dimensional code contains at least an identification number, which is expected to be assigned to each sample to be analyzed. "Assignment" refers to a one-to-one correspondence. In practice, this can be achieved by attaching the code to a bag or container when the soil sample is collected, by including the code in photographs of an excavated soil profile, or by attaching the code to a container containing the extracted liquid. The identification number is read from the image of the code displayed by the mobile device's camera using the code reader function. This allows the location information of the soil to be analyzed, the type of soil, the soil's physicochemical information, the sample to be analyzed, and the analysis results to be managed under a single identification number. "Analysis results" here refer to physicochemical information obtained during the analysis process, such as soil mass, concentration estimates, and the amounts or components contained in the soil. Using the location information P, it is possible to obtain information on the soil type and its corresponding physicochemical properties, such as the dry density ρd, from a database of soil map data available on the Web. Based on this information, it is possible to estimate the mass SW of the soil particles when a soil sample S of a certain soil volume SV is taken out of the soil sample container 20 using a measuring device and subjected to component analysis. Mass of soil particle (SW) = Dry density (ρd) × Soil volume (SV) The code may include operator information, which may be combined with other information. When using mobile terminal A, the terminal-specific information of the mobile terminal may be used as operator information. The above series of steps can be carried out on-site in the field.

[0014] Referring to FIG. 2, a method for adjusting the amount of soil sample and the extract using soil physicochemical information when using the method for analyzing soil components according to the present invention and an apparatus that realizes part of the method will be described. The left side of Figure 2 illustrates a mode in which a soil sample S collected on-site is directly analyzed, while the right side of Figure 2 illustrates a mode in which a soil sample S is removed from a stored soil sample container 20 and analyzed. In either mode, as in Figure 1, a mobile device or other device is used to capture a photograph of the soil sample and a code containing at least an identification number, resulting in a soil sample identified by the identification number and with location information. By referencing soil map data, the location information can be used to determine the type of soil and its dry density. Based on this information, the mass SW of the soil particles in a soil sample S with a given soil volume SV removed from the soil sample container 20 using a weighing device can also be estimated. The soil sample S is placed in a sample preparation container 21 containing water or solution O to produce a soil sample G for measurement, which is then subjected to component analysis.At this time, the ratio of solution to soil and the extraction ratio by the extractant (the ratio of the amount extracted by the extractant to the amount of the extractant) can be calculated from the above values, and the state of the soil sample G for measurement can be grasped, making it possible to adjust the amount of soil sample S and the amount of water or extractant O.

[0015] Referring to Figure 3, we will explain a soil adjustment method, i.e., a soil color stabilization method, for photographing a soil sample while suppressing light scattering from the soil sample and maintaining a constant soil color when using the soil component analysis method of the present invention and an instrument that realizes part of the method. [A] is a method for adjusting soil sample S, and the soil sample S is subjected to 0.2 kgf / cm 2The figure shows a case in which the soil sample is kneaded again to homogenize it, and then hydrated to saturate it, producing soil sample G for measurement. In addition to hydration, compression and kneading can reduce light scattering in soil sample S. Hydration refers to the injection of a solution containing a substance that suppresses light scattering, such as water or glycerin. Possible methods for applying pressure include pressing a flat cylinder with a diameter smaller than the inner diameter of the sample preparation container 21 against the soil sample, as shown in the figure, or applying pressure with a rubber stopper with a gas vent tube fitted into the sample preparation container 21. [B] is a method for adjusting soil sample S, in which water is added to the soil sample S to saturate it, and then the soil sample is kneaded and kneaded to a concentration of 0.2 kgf / cm 2 The above force is applied to compress the soil, reducing the air gap that causes light scattering, and the soil is then used as a measurement soil sample G. The order of the processes of adding water, compressing, and re-kneading is not limited to either (a) or (b), and the processes may be performed before or after or repeated.

[0016] Figure 4 illustrates an example of a method for photographing a soil sample using the soil component analysis method according to the present invention and an apparatus that realizes part of the method. [A], [B], [C], and [D] in Figure 4 illustrate methods for photographing a measurement soil sample G under conditions where light hits the sample from all directions, such as sunlight or indoor lighting L2. [E], [F], [G], [H], [I], [J], [J], and [K] in Figure 4 illustrate methods for photographing a measurement soil sample G under conditions where light is irradiated by a specific light source. The specific light source can be an artificial light source L1, such as a white LED. Under conditions where light hits the measurement soil sample G from all directions, the photographed surfaces of the measurement soil sample G are the top surface [A], bottom surface [B], side surface [C], and bottom surface [D] reflected by a mirror or other mirror surface. Under the condition that a specific light source illuminates the top surface of the measurement soil sample G, the photographed surfaces of the measurement soil sample G are the top surface [E], bottom surface [F], side surface [G], and bottom surface [H] reflected on a mirror or other surface. Also, under the condition that a specific light source illuminates a mirror surface from above, the photographed surface is the bottom surface [Ri] reflected on a mirror surface. The photographed surface when the specific light source illuminates the side of the measurement soil sample G is the side [N]. The photographed surface when the specific light source illuminates the bottom surface of the measurement soil sample G is the bottom [L].

[0017] Referring to Figure 5, we will explain an adjustment method for suppressing light scattering in the soil of the cross-section and an imaging method for directly photographing and analyzing the soil without collecting soil samples outdoors when using the soil component analysis method of the present invention and an apparatus that realizes part of the method. [I] shows the process of excavating to expose a soil profile, then spraying a solution of water or glycerin or other substances that suppress light scattering onto the soil surface to saturate it and keep it in a state of suppressed light scattering. An image of the soil profile under this saturated condition is then taken. This allows the soil's inherent, stable color to be measured. From the image taken under these conditions, a portion to be measured is selected, and the color of that portion of the soil is determined. The soil components are identified from the soil color. [B] shows the process of spraying a solution of water or glycerin, a substance that suppresses light scattering, onto the soil surface to saturate the soil surface and keep it in a state where light scattering is suppressed. An image of the soil surface under this saturated condition is then taken. This allows the soil's inherent, stable color to be measured. From the image taken under these conditions, a portion to be measured is selected, and the color of the soil in that area is determined. The soil components are identified from the soil color.

[0018] Referring to Figure 6, we will explain a method for analyzing soil without collecting soil samples outdoors, using the soil component analysis method of the present invention and an apparatus that realizes part of the method.The method involves using an alkaline solution to dissolve the humus in the soil, coloring it onto filter paper, and using this as a sample to photograph the color of the humus in the soil. [A] is excavated to expose the soil cross section, and an alkaline solution is sprayed there to dissolve soluble components such as humus in the soil. The eluted components are collected on filter paper 26, and the color of the filter paper 26 is photographed as an image. Photographing the filter paper 26 can be done not only on the side on which the eluted components were photographed, but also on the back side. In other words, when photographing the color of the filter paper 26, turning the filter paper 26 upside down photographs the color of the part 27 where the solution has permeated and does not contain soil particles. By photographing the filter paper, the color of the humus and other components in the soil can be measured. From the images photographed under these conditions, the area to be measured is selected, and the color of the soil in that area is determined. [B] An alkaline solution is sprayed on the soil surface to dissolve soluble components such as humus in the soil. The dissolved components are collected on filter paper 26, and the color of the filter paper 26 is photographed as an image. When photographing the color of the filter paper 26, the filter paper 26 can also be turned over and the color of the part 27 where the solution has permeated and does not contain soil particles can be photographed. This allows the color of the humus and other components in the soil to be measured. From the images photographed under these conditions, the part to be measured is selected, and the color of the soil in that area is determined. It should be noted that a water supply sheet or the like can be used instead of the above-mentioned filter paper 26. Also, instead of using filter paper, an alkaline solution can be sprayed to collect the eluate in a container, and a reflected light image or a transmitted light image of the eluate can be taken to determine the color of the eluate.

[0019] Referring to Figure 7, we will explain a method for extracting components from a soil sample using an extracting liquid, diluting and coloring the components, and measuring the components when using the soil component analysis method of the present invention and an apparatus that realizes part of the method. As a method for extracting components for soil analysis, a soil sample S of a certain soil volume SV is collected directly in the field, or the collected soil sample S is taken out at any location while still in the same wet, raw soil state as when it was collected, using a constant volume sample collector 22 to extract only a certain soil volume SV, and then placed in an extraction sample preparation container 30. Since the soil sample S has a certain soil volume SV, an estimate of the soil particle mass SW can be calculated using the dry density. An extract is placed in an extraction sample preparation container 30, and the supernatant is collected using a supernatant collection dropper 31 and poured into a dilution sample preparation container 32, which serves as the test liquid. If the concentration of the extracted component is high, the extract is dispensed into the dilution sample preparation container 32, and the test liquid is diluted with a diluent such as water. The extraction liquid used to extract components has a fixed volume, and the soil sample also has a fixed volume, so the ratio of soil to extraction liquid can be estimated.Even if the extraction liquid is dispensed or the test liquid is diluted, the ratio of soil to extraction liquid can be estimated because the amount of extraction liquid and the amount of dilution liquid used when dispensing are specified. In the process of extracting soil components, the extract or dilution solution contains soil particles, so the supernatant liquid is drawn up into a syringe with a dropper 33, and the soil particles are filtered using a filter tip or the like to obtain a clean extract or dilution solution, which is then placed in a coloring container 34, to which a coloring solution or coloring agent is added to color the components for component analysis, and this becomes the colored sample for measurement 35. The container containing the colored sample for measurement 35 can be any shape as long as it is a transparent container that does not interfere with photographing.

[0020] Referring to FIG. 8, a photographing method for acquiring an image of the measurement extract sample 28 or the measurement color sample 35 when using the soil component analysis method according to the present invention and an apparatus that realizes part of the method will be described. The measurement extract sample 28 is an extract containing components extracted from soil, and the measurement color-developing sample 35 is a sample in which the components extracted from soil have been colored. One method for capturing images of the measurement extract sample 28 or the measurement color sample 35 is to place the sample in a container over a light source and capture an image transmitted through the light [i]. Another possible method for capturing images of the measurement extract sample 28 or the measurement color-developing sample 35 is to capture an image of the reflected light from the sample under sunlight or indoor lighting conditions [b]. There is also a method [c] in which, in a cavity that fits a specified container such as a test tube, the container is fitted into the cavity to a position where light other than that from a specific light source will not illuminate the sample, and a light source is located on the side of the cavity in a position that illuminates the sample, and an image sensor or light receiving sensor with a light receiving unit is located opposite the light source across the test tube, and images or light reception are taken in this environment.

[0021] Referring to Figure 9, we will explain a method for measuring component concentrations by comparing the color of an image acquired from the above-mentioned measurement soil sample G or measurement extract sample 28 with the sample color when using the soil component analysis method of the present invention and an apparatus that realizes part of the method. In the captured image, the measurement points to be used for measuring the component concentrations are determined. Figure 9 shows the case where there are two measurement points. Note that it is possible to perform the measurement with only one measurement point, but the greater the variation in sample color, the more measurement points are preferred. Also, a portion without test solution (sample) where the component concentration is zero can be used as a (a) blank. Since it is normal for the measurement point to not have a single color, as in the (b) and (c) samples, the variation in the dots in the measurement point image is averaged, and the averaged color is determined as the color of the measurement point. Averaging is also effective when there are white gaps in the image. The sample color corresponding to that color is selected from a sample color table that corresponds to the component and soil type being analyzed. By preparing a standard concentration table that sets the component concentrations in the soil of the target component corresponding to the sample color table, the component concentration at each measurement point can be selected using this. Each value in the standard concentration table is set as a representative value or range of values ​​based on chemical analysis of the component concentration in the soil. The average sample concentration can be calculated by calculating the average value according to the number of measurement points and subtracting the blank value equivalent to zero. Once the component concentration is estimated, the amount of soil component can be calculated by multiplying it by the mass of the soil particle. The table in the figure has lightness in the columns and saturation in the rows, and the elements are organized at the granularity of the Munsell color system (JIS). In the above-described method for measuring component concentrations, the same process can be performed on points adjacent to the measurement point, and the component concentration can be estimated by averaging the calculated measurement values ​​for the adjacent points and the measurement value at the measurement point.

[0022] Referring to Figure 10, we will explain another method for measuring component concentrations by comparing the color of an image obtained from the above-mentioned measurement soil sample G, measurement extract sample 28, or measurement color sample 35 with the sample color when using the soil component analysis method of the present invention and an apparatus that realizes part of the method. FIG. 10 shows an exemplary embodiment in which, since there is also mechanical variation in the measurement of component concentration, multiple measurements are taken for one measurement point and the measured values ​​are averaged. In the captured image, the measurement points to be used for measuring the component concentrations are determined. A blank can also be determined as in Figure 9. The average sample concentration can be calculated by calculating the average value of each measurement value from multiple measurements, and subtracting the blank value as necessary. Once the component concentration has been estimated, the amount of soil component can be calculated by multiplying it by the mass of the soil particle. By taking multiple measurements at one measurement point, mechanical variations can be identified. The method in Figure 10 can be used in combination with the method in Figure 9. In the above-described method for measuring component concentrations, the same process can be performed on points adjacent to the measurement point, and the component concentration can be estimated by averaging the calculated measurement values ​​for the adjacent points and the measurement value at the measurement point.

[0023] A method for creating a standard concentration table in which component concentrations corresponding to a sample color table are shown will be described with reference to FIG. In measuring the concentration of target components using images of samples obtained by various soil treatments, it is necessary to create a table of sample colors and their corresponding concentrations in the soil. Since the color of the soil measurement sample and the color of the coloring liquid differ for each component, a corresponding sample color chart is created. To set up a table of component concentrations corresponding to the sample color table, an arbitrary number of soil component concentration samples are prepared and measured, and the soil component concentrations are assigned to the sample color table, as shown in Figure 11. Sample colors that are not filled in are handled by taking into account the adjacent component concentrations and assigning the average values ​​of the upper, lower, left, and right. When measurements are taken in practice and the sample color of the target is applied, standard component analysis, as would be done in a laboratory, can be performed and the component concentrations corresponding to the sample color can be corrected to improve accuracy. Not only do sample colors differ depending on the component being analyzed, but the sample colors also differ depending on the type of soil (alluvial, diluvial, black soil, etc.) Therefore, when performing component analysis using a sample color chart or standard concentration chart, a sample color chart for each component and soil type is required.

[0024] Here, we will further explain the method for analyzing the concentration of soil components using a sample color chart and a standard concentration chart. In this method, in addition to the above-mentioned samples such as images of the soil itself, images of soil in a state where the soil surface has been saturated and light scattering has been suppressed by spraying a solution in which water or a substance that suppresses light scattering, such as glycerin, the reflected or transmitted light of the leachate produced by adding an extract to the soil, and filter paper on which the leachate has been imaged, images whose color can be determined and whose color correlates with the components, from which the component concentration can be estimated, can also be used as samples. By preparing a sample color chart corresponding to the components to be analyzed and the type of soil, and a standard concentration table corresponding to the sample color chart and containing representative values ​​or ranges of values ​​determined by chemical analysis of the concentrations of soil components, it is possible to handle a wide variety of component analyses. The component concentration analysis method of the present invention, which uses a sample color chart and a standard concentration chart, uses images and can be performed on a mobile terminal, which is a prerequisite for making it a component analysis method that can be easily performed in the field.

[0025] An exemplary embodiment of the present invention implemented by an apparatus is described below. The device referred to here is a mobile terminal such as a smartphone or tablet equipped with a camera or GPS function, with the necessary software installed. By photographing the sample in the field along with a 2D code containing the identification number, the sample and the identification number can be linked. If the field location is also acquired using the GPS function, the location information of the soil being analyzed can also be linked. Once this information is acquired, a function of the software that realizes the physicochemical information communication unit acquires the soil type and dry density of the soil from the soil's location information via a communication network. A function of the software that realizes the physical condition estimation unit calculates an estimate of the mass of the soil particles from the dry density and the volume of the soil sample. Samples can be of various types, such as the soil itself, an excavated soil profile, the infiltrate obtained by immersing the soil in an extract, or a copy of the extract on filter paper. After capturing an image of the sample using the camera on the mobile device, any point in the image can be selected as a measurement point, and the color can be determined from the color information. The sample color table corresponding to the soil type and component, and the standard concentration table containing information on the soil component concentrations corresponding to each sample color on the sample color table and set with representative values ​​or numerical ranges obtained by chemical analysis, can be stored in the memory of the mobile device or in a database on a server connectable via a communications network. Software implementing the sample color table acquisition unit and standard concentration table acquisition unit acquires the information from either of these locations, and the software implementing the concentration estimation unit determines the color of the image, selects the sample color corresponding to that color from the sample color table, and selects the corresponding concentration from the standard concentration table. Alternatively, the image and selected measurement points can be sent to a server, where the server calculates the concentration estimates, and only the values ​​are received by the mobile device. The standard concentration table contains information on the concentrations of soil components, which correspond to the respective sample colors in the sample color table and have representative values ​​or ranges of values ​​determined by chemical analysis. Regardless of whether the analysis results are calculated using software on the mobile device or on the server side, the component analysis results, including physicochemical information such as dry density, soil type, components, component concentrations, and soil particle mass, can be exchanged between the mobile device and the server. Averaging of images at a measurement point to deal with white spots in the image, averaging of multiple measurement points to improve the reliability of the analysis, or averaging of multiple analysis results at a single measurement point can be configured to be achieved using software on a mobile device, but can also be performed on a server located on a communications network.

[0026] According to the present invention, it is possible to realize soil component analysis that can be carried out easily and with a high degree of freedom, whereas conventionally, chemical analysis of soil could not be carried out easily on site.

[0027] Although several embodiments of the present invention have been described above with reference to the drawings, embodiments that combine the characteristic features of each embodiment are also included in the present invention. Furthermore, various modifications are possible as long as they are in line with the gist of the present invention, and the present invention is not limited to the above-described embodiments.

[0028] Examples of the present invention and comparative examples are shown below. For the sake of convenience, the reference numerals used in the drawings may be used.

[0029] [Example 1] In the method of analyzing soil components, the color of the soil changes due to drying, so we demonstrate the effectiveness of a method of stabilizing the soil color by saturating the soil. Figure 12 shows the results of measuring the reflectance of each wavelength of light for soil samples under each soil moisture condition, using a soil sample from a paddy field on Oshima Island in Hokkaido. The soil was uniformly compressed and packed into a 50cc metal container by tamping, and then the soil was brought to (a) saturated conditions, and the soil moisture was adjusted by pressure to (b) pF 1.8 conditions (equivalent to one day after rainfall), and then further adjusted to (c) pF 3.0 conditions (the onset of drying for plants). Samples from 138 locations were used in this test, but only a representative sample is shown here.

[0030] As shown in Figure 12, the reflectance decreases as the soil dries. This shows that the apparent color changes depending on the change in soil moisture. Since soil moisture changes over time due to drying and wetting caused by rainfall, the conditions under which soil moisture can be artificially maintained at a constant level are saturated conditions. Therefore, saturated conditions are considered to be able to compare soil characteristics without being affected by soil moisture. This feature can be used to evaluate soil color using samples in saturated conditions where the soil surface has been homogenized by compression or other methods, making it possible to measure carbon, which is deeply involved in color, a basic soil characteristic. Furthermore, if the soil is uneven and the surface is rough and not homogeneous, light scattering will occur, so the soil surface must be homogenized by compacting (tamping), compressing, or kneading.

[0031] [Example 2] Referring to FIG. 13, an example is shown in which carbon concentration was measured from an image of an extract of an alkaline solution when using the soil component analysis method according to the present invention and an apparatus that partially realizes the method. In this example, a table of sample colors and their corresponding component concentrations was created based on a color image of the alkaline solution, and the digital image was used.

[0032] Test soil samples: Standard soil samples of alluvial soil (including peat soil), diluvial soil, and andosol from 110 locations nationwide were used by the Rural Engineering Research Division of the National Agriculture and Food Research Organization. Standard component analysis method for comparison: Total carbon concentration (%) by combustion method Extract: Alkaline solution Measurement items: Concentration conversion (%) based on transmitted light data using the method in Figure 8 In the laboratory of the Rural Engineering Research Department, an analysis of soil carbon concentration was attempted using the method of the present invention shown in Figure 8, using a plastic bottle containing an alkaline solution extract in advance and a plastic bottle containing distilled water for dilution. As a result, as shown in Figure 13, if the carbon concentration of the soil is up to 20%, it is possible to analyze the components by transmitting light through an alkaline solution extract, and it is practical to measure the component concentrations of the sample using a table.

[0033] [Example 3] Figure 14 shows how the components are measured by image measurement of the soil component extract and coloring solution when using the soil component analysis method of the present invention and an apparatus that realizes part of the method (left side of Figure 14). In this invention, the phosphate in the soil was extracted using an extractant of dilute hydrochloric acid, and a sample color chart and a table of the corresponding component concentrations were created in advance using the target standard concentration solutions and color images of several phosphate component concentrations and the purple color of the coloring solution, and these digital images were used.

[0034] Test soil sample: The Rural Engineering Research Division of the National Agriculture and Food Research Organization used the cultivated soil from a field converted from gray lowland soil to paddy in Tobetsu Town, Hokkaido, as a standard concentration sample of alluvial soil. Standard analytical method for comparison: Bray No. 2 method for assessing available phosphate Standard concentration: 52.1mg / 100g Measurement items: Concentration conversion based on the concentration change of the purple sample color chart (0-100mg / 100g) In the laboratory of the Rural Engineering Research Department, an analysis of available phosphate was attempted using the Bray No. 2 method, using the method shown in Figure 7 of the present invention, with a plastic bottle containing a diluted hydrochloric acid extract in advance, a plastic bottle for dilution containing distilled water, and a coloring container containing a coloring solution made from molybdenum sulfate. As a result, as shown in the right figure of Figure 15, it was possible to analyze the phosphate components of the soil, and the measured values ​​fell within the measurement category of the component concentration table of the sample color chart, which corresponds to the range of 40 to 50 mg / 100 g, making it practical.

[0035] The present invention has realized an inexpensive, simple, and rapid analytical method for determining soil physicochemical properties using a familiar device such as a camera-equipped smartphone. Soil analysis, which previously required specialized processing steps in a laboratory, can now be easily performed in the field by farmers and technicians. This means that an evaluation technology has been developed that can be easily implemented in the field to grasp the productivity of the field, its unevenness, and the results of improvement in cases where it is difficult to decide whether to apply top dressing due to poor growth that could not be addressed through prior soil analysis, whether to change planting or cultivated land, or whether soil improvement is necessary and how effective it is.This will not only strengthen the production of high-quality agricultural products, but will also contribute to reducing the use of fertilizer resources, which are becoming increasingly expensive. [Explanation of symbols]

[0036] A. Mobile device B. Sample container C Camera D Shooting direction L Light direction of the light source L1 artificial light source L2 sunlight and indoor lighting G Soil sample for measurement I Photographed image K mirror, mirror surface M station O Water or solution P Sampling position Q QR Code (registered trademark) S soil sample SV soil volume SW soil mass ρd dry density 10. Farmland 11 Soil profile 12. Range of saturated soil 20 Soil sample container 21 Sample preparation container 22 Sample fixed volume collection tool 23 Sample compression tool 24 Water and solution adding equipment 25 Spatula 26 filter paper 27 Extract infiltration area 28 Extract sample for measurement 30 Extraction sample preparation container 31 Supernatant collection dropper 32 Sample preparation container for dilution 33 Dropper 34 Coloring container 35 Color sample for measurement

Claims

1. excavating the soil to expose a soil profile; Photographing the soil surface of the soil profile using the mobile terminal having a camera function; and a step of determining the color and identifying the soil components based on the captured image.

2. The method for analyzing soil components according to claim 1, further comprising the step of treating or adjusting the surface of the soil profile for photographing.

3. 3. The method for analyzing soil components according to claim 2, wherein the step of treating or adjusting includes a step of spraying water or a solution containing a substance that suppresses light scattering onto the soil surface.

4. The treating or adjusting step includes a step of spraying an alkaline solution on the soil surface and transferring the leachate eluted on the soil surface onto filter paper; 3. The method for analyzing soil components according to claim 2, wherein in the photographing step, an image of reflected light from the filter paper is photographed instead of the soil surface.

5. The treating or adjusting step includes a step of spraying an alkaline solution on the soil surface and collecting the leachate eluted on the soil surface in a container; 3. The method for analyzing soil components according to claim 2, wherein in the photographing step, a reflected light image or a transmitted light image of the leachate is photographed instead of the soil surface.

6. a step of assigning a one-dimensional or two-dimensional code containing at least an identification number as information to an analysis object; reading the identification number from the assigned code using a mobile terminal having a code reading function; 6. The method for analyzing soil components according to claim 1, further comprising a step of linking location information of the soil to be analyzed, the results of the soil component analysis, and the identification number as information.

7. a sample color chart consisting of sample colors corresponding to the components and types of soil to be analyzed, for determining the color of the object to be photographed; a standard concentration table containing information on the concentrations of soil components corresponding to each sample color and having representative values ​​or ranges of values ​​determined by chemical analysis; determining a color of the image captured at the measurement point from color information of the image; selecting a sample color from the sample color table that corresponds to the color; 7. The method for analyzing soil components according to claim 1, further comprising the step of selecting, from the standard concentration table, a soil component concentration corresponding to the selected sample color, and setting the selected soil component concentration as an estimated value of the component concentration.

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