JP2001215203A - Instrument for measuring electric conductivity, method of measuring electric conductivity of soil, and instrument for measuring electric conductivity of soil solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric conductivity measuring instrument enhanced in meaurement precision, and to provide a soil conductivity measuring method and an instrument for measuring an electric conductivity of a soil solution enhanced in measuring precision using the electric conductivity measuring instrument. SOLUTION: Current routes (34, the first current route 44, the second current route 46) formed by power supply side electrodes (8, 10, the first electrode 38, the second electrode 40, the third electrode 42) in a measured object (soil 2) are limited in a specified range, voltages are taken out from the current routes by detection side electrodes 12, 14, 48, 50, an influence caused by a foreign matter 36 comprising an insulator and a good conductor contained in the object is evaded to enhance the precision of the electric conductivity, and the measuring precision in the method of measuring the electric conductivity of the soil solution is enhanced by using a measured value therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric conductivity measuring device, a soil electric conductivity measuring method, and a soil solution electric conductivity measuring device used for measuring electric conductivity such as grasping dynamics of fertilizer components and salts in soil.

[0002]

2. Description of the Related Art To grasp the dynamics of fertilizer components and salts in soil,
First, the conductivity is measured by measuring the conductivity of the soil solution and calculating the content of the soil component using the measured value. That is, since the electric conductivity of the soil is the reciprocal of the resistance, the measured value of the electric conductivity is used to calculate the soil conductivity (the reciprocal of the volume resistivity).
Can be calculated. Then, the conductivity of the soil solution is calculated using the soil conductivity, and the content of components such as fertilizer in the soil can be calculated using the conductivity of the soil solution.

[0003] By the way, the method of measuring the electrical conductivity of the soil by directly contacting the electrodes with the soil is simple, but the four-electrode method using a plurality of electrodes is adopted in order to avoid the influence of contact resistance. Have been. This quadrupole method is described in, for example, the document “4.
Polar Conductivity Measurement in Soil Columns and Its Application "
(Soil Physical Properties, Vol. 70 Separate Volume, November 1994, written by Mitsuhiro Inoue and Masao Shiozawa) and the like, and their commercialization is in progress.

[0004] A conventional electric conductivity measuring apparatus includes, for example, a sensor 100 shown in FIGS. In the sensor 100, power supply side electrodes 106 and 108 and detection side electrodes 110 and 112 are attached to a peripheral surface of an insulating support cylinder 104 in which an adhesive 102 is filled. A power supply 114 and a reference resistor 116 are connected to the power supply electrodes 106 and 108.
Are connected in series, and a voltmeter 118 is connected between the terminals of the reference resistor 116. A voltmeter 120 is connected between the detection-side electrodes 110 and 112. When the electric conductivity of the soil 122 is measured using the sensor 100, when the sensor 100 is buried in the soil 122, the voltmeter 118 displays the current path 124 of the soil 122.
The voltage V ₁ generated by the current flowing through the sensor and the resistance value R ₁ of the reference resistor 116 is detected, and the voltage V ₁ generated between the detection electrodes 110 and 112 from the soil 122 in the current path 124 is displayed on the voltmeter 120. ₂ is measured.
Assuming that the electric resistance between the detection-side electrodes 110 and 112 is R ₂ , there is a relationship of R ₂ / R ₁ = V ₂ / V ₁ .

[0005]

By the way, in this electric conductivity measuring apparatus, the situation around the sensor 100 in the object to be measured, that is, non-conductors such as plant roots, stones, and reeds, and good conductors such as metal pieces and the like. Current path 1 due to foreign matter 126 composed of
24 is disturbed, even if the soil has the same true moisture content and true soil solution conductivity, the measured value of the measured electrical conductivity may be different from the true value. The soil conductivity calculated using the measured values will also be different from the true value, causing a large error in the soil solution conductivity.

[0006] In other words, the influence of the change in the current path depends on the physical positional relationship between the preliminary experiment measurement for preparing the calibration curve and the actual soil measurement, that is, the difference in the measurement environment is an error factor. It is to become. The soil that is actually measured contains stones that affect the roots and conductivity of plants,
In the laboratory, it is difficult to predict and reproduce the information, and since the measurement is not performed in a specific container, the measurement error cannot be ignored. If a measurement value containing a large amount of error is used, the correlation between the electrical conductivity and the conductivity of the soil solution greatly differs depending on the type of soil, and if the measured electrical conductivity contains a large error, it is calculated accordingly. The conductivity of the soil solution differs greatly from the conductivity of the actual soil solution, and there is a problem in its practicality.

Therefore, the present invention provides an electric conductivity measuring device with improved measurement accuracy, and a soil conductivity measuring method and a soil solution electric conductivity measuring device with improved measurement accuracy using the electric conductivity measuring device. The purpose is to provide.

[0008]

The electric conductivity measuring device, the soil electric conductivity measuring method and the soil solution electric conductivity measuring device of the present invention provide a power supply side electrode (8, 10, 1st) on an object to be measured (soil 2).
Current path (34, 53, first current path 4) formed by the first electrode 38, the second electrode 40, and the third electrode 42).
4, the second current path 46) is limited to a specific range, and a voltage is detected from the current path to the detection-side electrodes (12, 14,.
48, 50) so as to avoid the influence of a foreign substance (36) made of an insulator or a good conductor contained in an object to be measured, to improve the measurement accuracy of electric conductivity, and to use the measured value. Thereby, the measurement accuracy of the method for measuring the conductivity of the soil solution can be improved.

According to a first aspect of the present invention, there is provided an electric conductivity measuring apparatus which is supported by an insulating support (6), faces the object (soil 2) through a current path (34) generated between the opposing surfaces. And a detection-side electrode (12, 14) for extracting a voltage from the current path. That is, a current path (34) formed on the device under test by the power supply side electrode is formed between the opposing surfaces of the opposing electrodes, and is determined in a specific range to suppress unnecessary spread. Since the voltage is taken out from the sensor by the detection side electrode, disturbance of the current path due to solid foreign matter such as an insulator or a good conductor contained in the object to be measured is suppressed, so that the accuracy of measuring the electric conductivity can be improved. .

According to a second aspect of the present invention, there is provided an electric conductivity measuring apparatus, comprising: an insulating support for accommodating an object to be measured (soil 2);
The power supply side electrodes (8, 1) are arranged at regular intervals to form a current path (34) in the device under test and allow a current to flow.
0), and are disposed at regular intervals in the current path,
A detection-side electrode (12, 1, 1) for extracting a voltage from the current path
4). In other words, since the device under test is accommodated inside the insulating support and a current path is formed by the power supply side electrode, the current path is specified within the insulating support and the current path does not spread, and the current path is detected from the specified current path. Since the voltage is extracted by the side electrode, the current path is not disturbed by solid foreign substances such as an insulator and a good conductor contained in the object to be measured, and the measurement accuracy of the electric conductivity can be improved.

According to a third aspect of the present invention, there is provided an electric conductivity measuring apparatus, wherein an insulating support (6) for accommodating an object to be measured (soil 2).
A first electrode (38), a second electrode and a third electrode (40, 42) sandwiching the first electrode, and a first electrode between the first electrode and the second electrode. A current path (44), a power supply side electrode that forms a second current path (46) between the first electrode and the third electrode to flow a current through the device under test, A detection-side electrode (48, 50) for extracting a voltage from the current path or the second current path. That is, the first and second current paths are formed by accommodating the DUT inside the insulating support and using the first to third electrodes of the power supply side electrodes.
Current path is specified in the insulating support, and the current path does not spread, and the voltage is taken out from the specified first or second current path by the detection-side electrode. The current path is not disturbed by solid foreign matter such as an insulator or a good conductor, and the accuracy of measuring the electrical conductivity can be improved.

According to a fourth aspect of the present invention, there is provided an electric conductivity measuring apparatus according to the present invention, comprising: a power supply side electrode for forming a current path between opposing electrode surfaces with respect to an object to be measured accommodated in an insulating support; A detection-side electrode provided at a side portion of the current path, for extracting a voltage from the inside of the current path. That is, since a current path is formed by a power supply side electrode having a counter electrode surface and an electric current flows through an object to be measured accommodated in the insulator, the current path is limited to the insulating support, and the current path does not spread. The current path is not disturbed by solid foreign matter such as an insulator or a good conductor. Since the voltage generated in the current path is detected by the detection-side electrode, the measurement accuracy of the electric conductivity can be improved.

According to a fifth aspect of the present invention, there is provided an electric conductivity measuring device according to the present invention, comprising: a power supply side electrode arranged at a constant interval on a peripheral surface of an insulating support to form a current path and flow a current to an object to be measured; Shielding means (insulating cylinder 54) for surrounding the power supply side electrode and the device under test to shield the current path, and a detection side electrode for extracting a voltage from the current path shielded by the shielding means. It is characterized by. That is, as a result of the current path formed in the DUT by the power supply side electrode being blocked by the shielding means, the current path does not spread, and the current path is not disturbed by solid foreign matter such as an insulator or a good conductor. That is, since the voltage generated in the current path surrounded by the shielding means is detected by the detection-side electrode, the measurement accuracy of the electric conductivity can be improved.

According to a sixth aspect of the present invention, a reference resistance (26) is connected to the power supply side electrode together with a power supply (28), and a voltage (V ₁ ) generated in the reference resistance is connected.
Is measured. That is, by using the voltage generated at the reference resistor as the reference voltage, the electrical conductivity γ can be measured from the ratio to the voltage (V ₂ ) extracted from the detection-side electrode.

According to a seventh aspect of the present invention, there is provided a soil conductivity measuring method, wherein the soil conductivity is calculated by using the electric conductivity measured by using the electric conductivity measuring device. That is, the soil conductivity (the reciprocal of the volume resistivity) is calculated from the measured value of the electrical conductivity, and the conductivity of the soil solution can be calculated using the soil conductivity. Then, using the conductivity of the soil solution, the content of components such as fertilizer or salt in the soil can be calculated, which can be useful for grasping the dynamics of fertilizer components and salt in the soil.

The soil solution conductivity measuring apparatus of the present invention according to claim 8 is a water absorbing medium (6) for absorbing the soil solution (62).
0) for accommodating the soil solution in the water-absorbing medium, and a current-supply-side electrode (8) that is arranged at a predetermined interval between the insulating support and a current path to flow the current through the soil solution in the water-absorbing medium. , 10) and detection-side electrodes (12, 14) which are provided at a constant interval in the current path and take out a voltage from the current path. That is, when the soil solution is absorbed by the water-absorbing medium accommodated in the insulating support and power is supplied to the power supply side electrode, a current path is formed in the soil solution and current flows. When the voltage generated between the detection electrodes is measured, the measured voltage indicates the soil solution conductivity. In this case, the soil solution is confined in the water-absorbing medium in the insulating support, and the current path is formed within the specified range, so that the current path is not disturbed by solid foreign matter such as an insulator or a good conductor. In addition, the measurement accuracy of the conductivity of the soil solution can be improved.

According to a ninth aspect of the present invention, there is provided a soil solution conductivity measuring apparatus according to the present invention, wherein the soil solution (62) absorbs water.
0), an insulating support (6) for accommodating the same, a first electrode (38) on the insulating support, and second and third electrodes (40, 42) sandwiching the first electrode. A first current path (44) between the first electrode and the second electrode, and a second current path (4) between the first electrode and the third electrode.
6) forming a feeder electrode for flowing a current through the soil solution in the water-absorbing medium, and a detecting electrode (48, 50) for extracting a voltage from the first current path or the second current path.
And characterized in that: That is, since the soil solution is absorbed by the water absorbing medium accommodated in the insulating support, and the first and second current paths are formed by the first to third electrodes on the power supply side electrodes, the first and second current paths are formed. Since the current path is specified by the water-absorbing medium in the insulating support and the current path does not spread, and the voltage is extracted by the detection-side electrode from the specified first or second current path, the solid path such as an insulator or a good conductor The current path is not disturbed by the foreign matter, and the measurement accuracy of the conductivity of the soil solution can be improved.

According to a tenth aspect of the present invention, there is provided a soil solution conductivity measuring apparatus according to the present invention.
0), a power supply-side electrode for forming a current path in the soil solution of the water-absorbing medium in the insulating support to allow a current to flow, and installed on a side of the current path; A detection-side electrode for extracting a voltage from the current path. In other words, a current path is formed by the power supply side electrode having the counter electrode surface to allow the current to flow through the soil solution absorbed by the water-absorbing medium contained in the insulating support. As a result, the current path does not spread, and the current path is not disturbed by solid foreign matter such as an insulator or a good conductor. Since the voltage generated in the current path is detected by the detection-side electrode, it is possible to improve the measurement accuracy of the conductivity of the soil solution.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

1 to 3 show a first embodiment of the electric conductivity measuring apparatus according to the present invention. FIG. 1 is a side view and a measuring circuit of the sensor, FIG. 2 is a plan view of the sensor, and FIG. FIG. 3 shows a cross-sectional view taken along line III-III of the sensor shown in FIG. 2. The electrical conductivity measuring device includes a measuring circuit 5 together with a sensor 4 for making electrical contact with, for example, the soil 2 as an object to be measured. The sensor 4 is provided on a peripheral surface of a cylindrical insulating support 6 with a power supply side electrode. 8, 10 and the detection-side electrodes 12 and 14 are attached. The power supply-side electrodes 8 and 10 are provided with flanges 16 and 18 protruding from the end face side of the insulating support 6 at a constant width and a constant interval.
Is mounted in the form of being buried in the opposite surface side. The detection electrodes 12 and 14 are provided on the surface of the insulating support 6 sandwiched between the flanges 16 and 18.
Are provided inside the concave portions 20, 22 formed at a predetermined interval from, and the surface thereof recedes from the peripheral surface of the insulating support 6 to the inside of the concave portions 20, 22. The inside of the insulating support 6 is filled with an insulator 24 such as an adhesive. In addition, the shape of the insulating support 6 is a shape other than the cylindrical shape,
A rectangular tube may be used, and the insulating support 6 may be used instead of the internal insulator 24.
May be formed of a solid insulating material. In addition, the power supply-side electrodes 8 and 10 may be provided so as to protrude from the surface portions of the flanges 16 and 18, and the detection-side electrodes 12 and 14 may be provided so as to protrude from the peripheral surface of the insulating support 6. The electrodes 8 and 10 and the detection electrodes 12 and 14 do not need to be formed on the entire periphery of the insulating support 6, and may be partial.

A power supply 28 is connected to the power supply electrodes 8 and 10 via a reference resistor 26.
May be either an AC power supply or a DC power supply. Reference resistance 26
The first voltmeter 30 is connected as a means for measuring the reference voltage V ₁ between the terminals
14 second voltmeter 3 as a voltage measuring means of the voltage V ₂ to
2 are connected.

With this configuration, as shown in FIG. 3, the current path 3 is provided between the opposing surfaces of the power supply electrodes 8 and 10 surrounded by the flanges 16 and 18 projecting from the insulating support 6.
4 are formed. The current path 34 includes the detection-side electrode 1
2 and 14 are exposed, and a voltage V ₂ generated between the detection-side electrodes 12 and 14 through the soil 2 in the current path 34.
Is detected by the voltmeter 32. Further, the voltmeter 30 detects a voltage given by the product of the current i flowing on the power supply side and the resistance value R ₁ of the reference resistor 26, that is, the reference voltage V ₁ .

Here, the ratio between the current i flowing on the power supply electrodes 8 and 10 and the voltage V ₂ on the detection electrodes 12 and 14, that is, i / V ₂ is the ratio of the soil 2 which is the object to be measured. It is inversely proportional to resistance, and this value is electrical conductivity. In this case, almost no current flows on the detection side electrodes 12 and 14 side, so that the influence of local resistance such as contact resistance between the detection side electrodes 12 and 14 and the soil 2 can be avoided. When a measurement error due to the polarization of the electrode is a problem, a high-frequency AC may be supplied from the power supply 28.

[0024] Then, the current i flows to the reference resistor 26, the voltage by the product of the reference resistor 26 and the current i and the resistance value R ₁ V
₁ occurs. Since the voltage V ₁ is measured by the voltmeter 30, the current i is obtained from the equation (1). i = V ₁ / R ₁ (1) Then, the electric conductivity γ of the soil 2 is given by: γ = k ₁ (i / V ₂ ) = k ₁ (V ₁ / R ₁ ) / V ₂ = k ₂ V ₁ / V ₂ (2), which is obtained from the voltage ratio V ₁ / V ₂ . Note that k ₁ and k ₂ (= k ₁ / R ₁ ) are proportional constants.

The current path 34 is specified between the opposing surfaces of the power supply electrodes 8 and 10, and is not limited to a certain range without unnecessary spread. Therefore, the current path 3
4 is not disturbed by a solid foreign matter 36 such as an insulator or a good conductor, so that the measurement accuracy of the measured voltage is high,
The electrical conductivity γ of the measured object such as the soil 2 can be measured with high accuracy.

4 and 5 show a second embodiment of the electric conductivity measuring apparatus according to the present invention. FIG. 4 is a plan view of the sensor 4 and FIG. 5 is a sensor 4 shown in FIG. 2 shows a cross section taken along line VV of FIG. In this embodiment, the soil 2 as an object to be measured is accommodated in a cylindrical insulating support 6, and a current path is confined in the internal space of the insulating support 6. An insulating cylinder such as a vinyl chloride pipe is used for the insulating support 6, and first, second, and third electrodes 38, 40, and 42 are installed on the inner peripheral surface side as measurement electrodes. Each of the electrodes 38, 40, and 42 has a constant width b, and the electrode 38 is provided at the center when viewed from the end surface side of the insulating support 6, and the electrodes 40, 42 are arranged. And electrode 3
8 and the electrode 40, the first current path 44 is formed between the electrode 38 and the electrode 42, and the second current path 46 is formed between the electrode 38 and the electrode 42.
The detection side electrodes 48 and 50 are provided between 40.

The reference resistance 26 is applied to the electrodes 38 and 40.
, And the power supply 28 is connected to the electrodes 38 and 42 via an adjusting resistor 27 having the same resistance value as the resistance value R ₁ of the reference resistor 26. This power supply 28 may be either an AC power supply or a DC power supply. A first voltmeter 30 is connected between the terminals of the reference resistor 26 as a means for measuring the reference voltage V _1.
Second voltmeter 32 is connected as a voltage measuring means of the voltage V ₂ to 8,50.

As described above, the soil 2 to be measured is accommodated in the insulating support 6 and the current paths 44 and 46 are confined therein, so that there is no influence of peripheral foreign substances at all. For the soil 2 inside the support 6, the voltage V
₁ , V ₂ can be measured, and the electric conductivity of the soil 2 can be measured. Further, the electric conductivity of the soil 2 can be measured and the measurement accuracy can be improved only by filling the soil 2, which is the object to be measured, into the insulating support 6, that is, the container.

Next, FIG. 6 shows a third embodiment of the electric conductivity measuring apparatus of the present invention. That is, in this embodiment, the electrodes 40 and 42 are short-circuited and shared, and the power supply 2 is connected between the short-circuit 52 and the electrode 38 via the reference resistor 26.
By connecting 8, the common current i can flow through the reference resistor 26 to the electrodes 40 and 42, so that the adjusting resistor 27 in the measuring circuit 5 shown in FIG.

Next, FIG. 7 shows a fourth embodiment of the electric conductivity measuring apparatus according to the present invention. That is, the reference resistance 2
6 and the resistance values R ₁ and R ₂ of the adjustment resistor 27, the width b _{2 of the} electrode 42 is larger than the width b _{1 of the} electrode 40 (>).
b ₁ ) can be made large and the interval pitch h ₂ between the electrodes 38 and 42 can be set smaller than the interval pitch h ₁ between the electrodes 38 and 40. In this way, the length of the insulating support 6 can be set shorter than that of the sensor 4 shown in FIG. The electrodes 40 and 42 do not need to be provided on the inner peripheral surface of the insulating support 6, and may be provided on the opening end surface side of the insulating support 6.

Next, FIGS. 8 and 9 show a fifth embodiment of the electric conductivity measuring device of the present invention, and FIG.
FIG. 9 shows a cross section taken along line IX-IX of the sensor 4 shown in FIG. That is, in this embodiment, the insulating support 6 for accommodating the soil 2 as the object to be measured is formed in a rectangular parallelepiped, and the plate-shaped power supply side electrodes 8 and 10 are provided on the inner wall surface in the longitudinal direction. The electrodes are arranged to face each other, and the narrow detection-side electrodes 12 and 14 are provided on one of the inner wall surfaces in the width direction. The reference electrodes 2 are connected to the power supply side electrodes 8 and 10.
The power supply 28 is connected via the power supply 6 and may be either an AC power supply or a DC power supply. Further, between the reference resistor 26 terminals are first voltmeter 30 is connected as a means of measuring the reference voltage V _1, also detecting side electrode 1
Second voltmeter 32 is connected as a voltage measuring means of the voltage V ₂ to 2,14.

As described above, the soil 2 to be measured is accommodated in the rectangular parallelepiped insulating support member 6, and the current path 53 is confined in the insulating support member 6 on the surface facing the power supply electrodes 8 and 10. Since the detection electrodes 12 and 14 are provided on the side of the current path 53, the voltages V ₁ and V are applied to the soil 2 inside the insulating support 6 on the side surface without being affected by foreign substances at the periphery. ₂ can be measured, and the electric conductivity of the soil 2 can be measured. In addition, the electric conductivity of the soil 2 can be measured and the measurement accuracy can be improved only by filling the soil 2 as the object to be measured into the insulating support 6, that is, the container.

Next, FIG. 10 shows a sixth embodiment of the electric conductivity measuring apparatus of the present invention. That is, while the soil 2, which is an object to be measured, is accommodated in an insulating support 6 formed in a rectangular cylindrical shape or a cylindrical shape, a pair of power-supply-side electrodes 8, 10 are provided on the inner peripheral surface thereof at a predetermined interval. The pair of detection electrodes 12, 1 are provided within the space between the power supply electrodes 8, 10.
4 are provided, and a similar measuring circuit 5 shown in FIG. 1 is formed. When the pair of feeding electrodes 8 and 10 and the detection electrodes 12 and 14 are respectively installed in a cylindrical shape in this manner, the soil 2 that is the object to be measured is accommodated inside the insulating support 6 and the current path is formed through the inside. The voltage V ₁ , V ₂ can be measured for the soil 2 inside the insulating support 6 without being affected by foreign substances at the periphery, and the electric conductivity of the soil 2 can be obtained by using the equation (2). Can be calculated, and the measurement accuracy can be improved.

FIGS. 11 to 13 show a seventh embodiment of the electric conductivity measuring apparatus according to the present invention. FIG. 11 is a plan view of the sensor 4, FIG.
FIG. 13 shows a cross section taken along line XIII-XIII of the sensor 4 shown in FIG. This embodiment is a sensor 4 embedded in the soil 2 as an object to be measured, in which a pair of power supply side electrodes 8 and 10 are provided on a peripheral surface of a cylindrical insulating support 6 filled with an insulator 24. A pair of detection side electrodes 1 are provided at regular intervals, and within a space between the power supply side electrodes 8 and 10.
2 and 14 are provided, and the same measurement circuit 5 shown in FIG. 1 is formed. By installing an insulating tube 54 as a cylindrical shielding means on the peripheral surface of the sensor 4 with the soil 2 interposed therebetween, the current path is confined around the sensor 4 by confining the soil 2 as an object to be measured. The soil 2 surrounded by the insulating tube 54 without being affected by any foreign matter around the
, The voltages V ₁ and V ₂ can be measured, the electrical conductivity of the soil 2 can be calculated using the equation (2), and the measurement accuracy can be improved.

Next, an embodiment of a soil conductivity measuring method using the electric conductivity measuring device of the present invention will be described.

When the conductivity of the soil solution is measured using the electric conductivity measured by the electric conductivity measuring device shown in FIGS. 1 to 13, a first correlation equation is obtained as a first step. That is, the sensor 4 is buried in an object whose conductivity is known, and the electric conductivity of the object is measured. Next, the conductivity of the device under test around the sensor 4 is adjusted to a plurality of levels, and the electrical conductivity of each is measured. The measured values of the electric conductivity and the electric conductivity are plotted on a graph, and a calibration curve shown in FIG. 14 is created. This correlation is a linear function, and the function is obtained from this calibration curve.
Get. y = ax + b (3) In this case, an aqueous solution of potassium chloride or sodium chloride is used as an object to be measured, the electric conductivity is measured, and the electric conductivity is adjusted by adjusting the concentration. The measured value is defined as the conductivity.

Even if the object to be measured around the sensor 4 is the same, each electrode (8, 10, 12, 14, 3
8, 40, 42, 48, and 50), the measured values of the electrical conductivity may differ when the measured values are different from each other. It is necessary to create every four.

Then, soil is measured as an object to be measured.
The sensor 4 is buried in the soil to be measured, and the electric conductivity is measured. The value is put into the correlation equation (3), and the conductivity of the soil is calculated.

As a second step, a second correlation equation is created.
That is, the conductivity is measured under each condition using one type of soil in the first stage. Specifically, the water content of a certain soil and the conductivity of the contained water (hereinafter referred to as soil solution conductivity) are adjusted to several levels, and the conductivity at each time (hereinafter referred to as soil conductivity) is adjusted. ) Is measured, and the soil conductivity with respect to the soil solution conductivity and the soil conductivity with respect to the water content are plotted, and FIG. 15 and FIG. 16 are created. And from the correlation of soil conductivity, soil solution conductivity and water content,
The correlation equations (4) and (5) are created.

ECa = f (ECw, θ) (4) ECw = g (ECa, θ) (5)

The correlation equations (4) and (5) indicate that, for example, when the object to be measured is Tottori sand dune sand and the aqueous sodium chloride solution is used as the soil solution,
If the soil solution conductivity is constant, the correlation between them becomes a quadratic function. Also, in the case of the soil conductivity with respect to the soil solution conductivity, when the moisture content is constant, the correlation between the two becomes a linear function. From these results, the following correlation equation (6) can be derived.

ECa = a · ECw · θ ² + b · θ (6)

Here, in the correlation equation (6), ECa:
Soil conductivity [dS / m], ECw: soil solution conductivity [dS / m], θ: amount of water contained per soil volume [cm ³ / cm ³ ], a and b: obtained from experimental results Is a constant.

In the measurement of the conductivity of the soil solution, the sensor 4 is buried in the soil to be actually measured. The electric conductivity at that time is measured, the soil electric conductivity is calculated from the value, and the measured value is put into the correlation equation (6) together with the water content previously measured by another method, thereby obtaining the soil solution electric conductivity σ. Can be calculated.

In the third stage, the fertilizer component content in the soil is calculated from the soil solution conductivity obtained in the second stage using the calibration curve shown in FIG. 17, and the dynamics of the fertilizer component and salt in the soil are calculated. Can grasp. The calibration curve shown in FIG.
The horizontal axis represents soil solution conductivity ECw [S / m], and the vertical axis represents the concentration [g / m ³ ] or [mol / m ³ ] of inorganic nitrogen or salt as the concentration of a component of the soil solution. Yes,
This calibration curve is, for example, after drying soil collected from many different tea fields, adjusting the water content to a certain level by adding pure water, collecting the soil solution, measuring the conductivity, and measuring the conductivity. The horizontal axis is set, and the vertical axis is set by measuring the content of fertilizer components of the soil, for example, inorganic nitrogen or salt by chemical analysis. That is, according to this calibration curve,
The concentration of inorganic nitrogen or salt [g / g
m ³ ] or [mol / m ³ ].

Next, an embodiment of the soil solution conductivity measuring device of the present invention will be described.

FIGS. 18 to 22 show an embodiment of the soil solution conductivity measuring apparatus according to the present invention. The constructions of the sensor 4 and the measuring circuit 5 are shown in FIGS. 5, 6, 7, 8 and The electric conductivity measuring device shown in FIG. 10 is the same as the electric conductivity measuring device shown in FIG. 10 except that a porous water-absorbing medium 60 such as unglazed is installed inside the insulating support body 6 and the measurement target The point is that the soil solution 62 as a substance is absorbed.

Then, the electric conductivity of the medium is measured from the equation (2) using the voltages V ₁ and V ₂ measured through the measuring circuit 5 connected to the sensor 4, and the calibration curve shown in FIG. 14 is used. Then, the conductivity of the medium can be calculated, and the conductivity can be calculated by using the conductivity in equation (6). In this case, in the soil solution 62 held in the water absorbing medium 60, the current paths described with reference to FIGS. 5, 6, 7, 8, and 10 are confined in the insulating support 6, and the current paths spread. In addition, since there is no influence of foreign substances such as insulators and good conductors and the current path is not disturbed, the measurement accuracy of the voltages V ₁ and V ₂ is improved, and the measurement accuracy of the soil solution conductivity can be increased. . That is, although it is expected that the constant of the equation (6) differs depending on the type of soil, in order to eliminate the difference in the measured values, only the soil solution is absorbed by the water absorbing medium 60 having a specified range, and the electric conductivity is measured. Then, the soil solution conductivity σ is calculated.

From the calculated soil solution conductivity σ, as described above, the fertilizer component content in the soil can be calculated using the calibration curve shown in FIG. 17, and the dynamics of the fertilizer component and salt in the soil can be grasped. Can be performed with high accuracy.

In each of the embodiments, the soil 2 or the soil solution 62 is taken as an example of the object to be measured. However, the present invention is used for measuring the electric conductivity and the electric conductivity of the object to be measured other than the soil. The present invention is not limited to the embodiment.

[0051]

As described above, according to the present invention,
The following effects are obtained. a The current path is not disturbed by a foreign substance due to an insulator or a good conductor contained in the object to be measured, and the electric conductivity and the electric conductivity of the object to be measured such as soil can be measured with high accuracy. b By using the measured electric conductivity, it is possible to improve the measurement accuracy, for example, to improve the calculation accuracy of the soil solution conductivity as an object to be measured and to more accurately grasp the dynamics of the soil component. it can. c Since a current path is formed in the soil solution absorbed by the water absorbing medium in the insulating support, the current path is specified in the insulating support and does not spread unnecessarily, and the current path is disturbed by foreign substances such as an insulator or a good conductor. Therefore, it is possible to improve the measurement accuracy of the conductivity of the soil solution and contribute to the improvement of the reliability of grasping the dynamics of fertilizer components and salts in the soil.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an electric conductivity measuring device of the present invention.

FIG. 2 is a plan view showing the sensor shown in FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2, showing a current path formed in the soil by the sensor.

FIG. 4 is a plan view of a sensor showing a second embodiment of the electric conductivity measuring device of the present invention.

5 is a diagram showing a cross section taken along line VV of the sensor shown in FIG. 4 and a measurement circuit.

FIG. 6 is a view showing a third embodiment of the electric conductivity measuring device of the present invention.

FIG. 7 is a diagram showing a fourth embodiment of the electric conductivity measuring device of the present invention.

FIG. 8 is a view showing a fifth embodiment of the electric conductivity measuring device of the present invention.

9 is a sectional view of the sensor shown in FIG. 8, taken along line IX-IX.

FIG. 10 is a view showing a sixth embodiment of the electric conductivity measuring device of the present invention.

FIG. 11 is a plan view of a sensor showing a seventh embodiment of the electric conductivity measuring device of the present invention.

FIG. 12 is a partial sectional view of the sensor shown in FIG. 11;

13 is a diagram showing a cross section taken along line XIII-XIII of the sensor shown in FIG. 11 and a measurement circuit.

FIG. 14 is a diagram showing a calibration curve representing a correlation between electric conductivity around a sensor and electric conductivity.

FIG. 15 is a diagram showing a correlation between conductivity around a sensor and conductivity of a soil solution.

FIG. 16 is a diagram showing a correlation between conductivity around a sensor and soil moisture content.

FIG. 17 is a diagram showing a calibration curve representing a correlation between the component concentration of a soil solution and the conductivity of the soil solution.

FIG. 18 is a view showing a first embodiment of the soil solution conductivity measuring device of the present invention.

FIG. 19 is a view showing a second embodiment of the soil solution conductivity measuring device of the present invention.

FIG. 20 is a view showing a third embodiment of the soil solution conductivity measuring device of the present invention.

FIG. 21 is a view showing a fourth embodiment of the soil solution conductivity measuring device of the present invention.

FIG. 22 is a diagram showing a fifth embodiment of the soil solution conductivity measuring device of the present invention.

FIG. 23 is a plan view showing a sensor of a conventional electric conductivity measuring device.

FIG. 24 is a side view showing a sensor of a conventional electric conductivity measuring device.

FIG. 25 is a diagram showing a sensor and a measurement circuit of a conventional electric conductivity measuring device.

[Explanation of symbols]

 2 Soil (measured object) 4 Sensor 5 Measurement circuit 6 Insulating support 8, 10 Feeding electrode 12, 14 Detection side electrode 26 Reference resistance 28 Power supply 34 Current path 38 First electrode (Feeding electrode) 40 Second Electrode (feeding-side electrode) 42 Third electrode (feeding-side electrode) 44 First current path 46 Second current path 48, 50 Detection-side electrode 54 Insulating cylinder (shielding means) 60 Water-absorbing medium 62 Soil solution

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G028 AA01 BC06 CG02 DH03 DH05 DH14 FK01 HN02 HN11 HN13 LR01 2G060 AA14 AC02 AE17 AF02 AF03 AF08 AG04 AG11 CA03 HC06

Claims (10)

[Claims] 1. A power supply side electrode which is supported by an insulating support member and faces and which flows a current to a device under test through a current path generated between the opposing surfaces, and a detection side electrode which extracts a voltage from the current path. An electrical conductivity measuring device, characterized in that: 2. A power supply side electrode which is arranged at a predetermined interval on an insulating support for accommodating an object to be measured, forms a current path in the object to be measured, and allows a current to flow, and a fixed electrode in the current path. An electrical conductivity measuring device, comprising: a detection-side electrode that is installed at an interval and extracts a voltage from the current path. 3. An insulating support for accommodating an object to be measured, comprising a first electrode, and second and third electrodes sandwiching the first electrode, wherein the first electrode and the second electrode are connected to each other. A first current path between the first and third electrodes and a second current path between the first and third electrodes.
And a detection-side electrode for extracting a voltage from the first current path or the second current path. Electric conductivity measuring device. 4. A power supply-side electrode for forming a current path between opposing electrode surfaces with respect to an object to be measured housed in an insulating support and allowing a current to flow therethrough; An electrical conductivity measurement device comprising: a detection-side electrode for extracting a voltage from the inside; 5. A power supply-side electrode which is arranged at a constant interval on a peripheral surface of an insulating support and forms a current path to flow a current to a device under test, and surrounds the power supply-side electrode and the device under test. An electric conductivity measurement device, comprising: a shielding unit that shields the current path; and a detection electrode that extracts a voltage from the current path that is shielded by the shielding unit. 6. The electric conductivity measuring apparatus according to claim 1, wherein a reference resistance is connected to the power supply side electrode together with a power supply, and a voltage generated at the reference resistance is measured. . 7. An electric conductivity of soil is calculated by using an electric conductivity measured by using the electric conductivity measuring device according to claim 1, 2, 3, 4, 5, or 6. Soil conductivity measurement method. 8. An insulating support for accommodating a water-absorbing medium for absorbing a soil solution, and a current path formed in the insulating support at a predetermined interval to form a current path in the soil solution in the water-absorbing medium. A soil solution conductivity measuring device, comprising: a power supply side electrode through which a current flows, and a detection side electrode which is provided at a predetermined interval in the current path and takes out a voltage from the current path. 9. An insulating support for containing a water-absorbing medium for absorbing a soil solution, a first electrode on the insulating support, and second and third electrodes with the first electrode interposed therebetween. The first electrode and the second electrode
A current path between the first electrode and the third electrode, and a second current path between the first electrode and the third electrode to supply a current to the soil solution in the water absorbing medium. An apparatus for measuring the conductivity of a soil solution, comprising: an electrode; and a detection electrode for extracting a voltage from the first current path or the second current path. 10. An insulating support for accommodating a water-absorbing medium for absorbing a soil solution, a power-supply-side electrode for forming a current path in the soil solution of the water-absorbing medium in the insulating support and flowing a current, and the current path And a detection-side electrode that is installed on a side of the device and extracts a voltage from within the current path.