JPH02308731A - Nutritive solution culture device - Google Patents

Abstract

PURPOSE:To obtain the title device capable of accurately controlling the composition of components in a nutritive solution by repeatedly measuring ionic concentration of the components in the nutritive solution plural times at every measuring period and using coincident measured values as an accurate ionic concentration. CONSTITUTION:In the above-mentioned nutritive solution culture device, ionic concentration of a nutritive solution 3 at every fixed period is repeatedly measured plural times. A checking means of measured value finds out approximately coincident measured values among repeatedly measured values of ionic concentration as the measured value of ionic concentration in every measuring period. The measured value is as an accurate ionic concentration in the measuring period is sent to a controller 23. Then, in the controller 23, the accurate measured value of ionic concentration is compared with a given reference value and when a deficient component is found, a supply order of the component is outputted to a component regulator 28. Then, in the device 28, a necessary component is supplied to the nutritive solution 3 based on the component supply order from the controller 23 and various nutritive components of the nutritive solution are always maintained in a composition suitable for plants 7 during culture.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a hydroponic cultivation device for plants.

(Conventional technology) In order to produce large quantities of vegetables and fruits with almost constant quality, in recent years, nutritional components suitable for plant growth, such as N, have been developed.
2. Description of the Related Art Hydroponic cultivation techniques for cultivating plants using a nutrient solution in which , Ca, P, Mg, etc. are dissolved have been attracting attention.

In this type of hydroponic cultivation, various nutritional components such as N, Ca, P, and Mg are added to the nutrient solution according to the plant growth process, as well as conditions such as sunlight, temperature, concentration, and time of day. In addition to the need to change the composition, it is also necessary to manage the components to maintain the composition suitable for each growth process, but in order to control the various components in the nutrient solution, it is necessary to control the actual ions of the various components in the nutrient solution. The concentration must be measured and understood.

In order to meet these demands, recently, ion meters using ion-selective electrodes have been used, and various components of the nutrient solution, such as K", Ca", NO3, etc., are measured using an online system.
A hydroponic cultivation device that measures ion concentrations such as - on-line has been proposed.

Figure 5 shows an example of such a hydroponic system, in which a plant bed 2 is placed in a house 1, and three nutrients suitable for plant growth, such as nitrogen, N, phosphate, P, O, and potassium, are added. Magnesium Mg1 Manganese Mn,
A pump 5 supplies the nutrient solution 3 from the nutrient solution tank 4, which stores the nutrient solution 3 containing calcium, Ca, etc. dissolved in water, to the plant bed 2 through a pipe 6, and the flowers and other plants planted in large numbers in the plant bed 2 are supplied to the plant bed 2 through a pipe 6. It is equipped to grow plants 7 such as vegetables.

The ideal component composition of the nutrient solution 3 varies depending on the type of plant to be grown, the growth stage of the plant, sunlight, temperature, loading level, time of day, etc. If you do not constantly monitor the composition and replenish the missing ingredients without fail, growth may be slow, beautiful flowers may not be produced, and fine fruit may not be produced. In some cases, the nutrients in the nutrient solution have been completely replaced by waste products excreted by the plants, without even realizing it, and the nutrients are only consumed when the plants wither. It is possible that this could result in significant damage being incurred.

Therefore, in the device shown in Fig. 5, the nutrient solution tank 4 has a pH meter 8,
A conductivity meter 9 and a liquid thermometer 10 are installed to manage the components of the nutrient solution 3, and an ion meter 11 using an ion selection electrode is also installed, and each component of the nutrient solution is measured in terms of ion concentration. The status of the component composition is monitored online.

The ion meter 11 used here is capable of measuring, for example, potassium ions K + , calcium ions Ca'', nitrate ions N
The ion concentrations of the three components 01- are measured simultaneously, the measured values are displayed on the display windows 11a to 11c, and the printer 1
2) The components of the nutrient solution 3 are continuously measured intermittently at regular intervals, and when the ion concentration of a certain component drops below a predetermined value, the ion component is replenished. The stock solution is replenished from the stock solution tank (not shown) to the nutrient solution tank 4 to prevent ingredient shortages.

When measuring the ion concentration in each cycle of the ion meter 11, a high-concentration calibration solution in which each component ion to be ill-defined is present at a predetermined high concentration, and a calibration solution in which each component ion is present at a predetermined low concentration are used. Concentration calibration solutions are taken in from the high concentration calibration solution tank 13 and the low concentration constituent solution tank 14, respectively, and the voltage values indicated by the ion selective electrodes for each of these ion components are measured to obtain a calibration curve for each component ion, Next, the sampled nutrient solution taken out from the nutrient solution tank 4 is taken into the sampling tank 16 by the sampling pump 15 into the ion meter 11, and the voltage value of each component ion dissolved in the nutrient solution is selected as an ion. The ion concentration of each component in the nutrient solution is determined by reading the output voltage of the electrostatic electrode and referring to the calibration curve, which is displayed as a measured value on the display windows 118 to 11c and printed out by the printer 12. Note that 17 is a drain tank for the calibration solution and sampling nutrient solution that have been measured.

In this way, by constantly monitoring each component in the nutrient solution 3 by measuring ion concentration, it is possible to replenish nutrients immediately if they become insufficient, and to accurately manage the components. Therefore, plants can be grown effectively.

(Problem to be Solved by the Invention) However, in the above-mentioned hydroponic cultivation apparatus, although the components can be managed using an ion meter that can accurately measure ion concentration, the ion meter is a precision device. Even if a small amount of foreign matter enters the JPJ constant part, there is a risk that an abnormal measured value will be output, and if component management is performed based on such an abnormal ΔIII constant value, appropriate component management may not be possible. It is possible that

In addition, during hydroponic cultivation, plants may expel waste products and nutrients from their roots into the nutrient solution, making it difficult to accurately determine the composition of the nutrient solution with a single ion concentration measurement. ,
If component management is performed based on such a one-time ion concentration Δp1 constant, there is a risk that the appropriate component composition may be disrupted.

On the other hand, fluctuations in the composition of nutrients in the nutrient solution are gradual;
There is no need to adjust the nutrient solution components in accordance with moment-to-moment fluctuations, and it is possible to adequately respond by adjusting the components according to component fluctuations over a long period of time, such as 1 hour to 3 hours. .

This invention was made based on such consideration,
It is an object of the present invention to provide a hydroponic cultivation device that can accurately manage the composition of each component in a nutrient solution.

[Structure of the Invention] (Means for Solving the Problems) A hydroponic cultivation apparatus according to claim 1 of the present invention includes: an ion meter that measures the ion concentration of various components contained in a plant cultivation nutrient solution; a control means for causing the meter to repeatedly determine the ion concentration of the nutrient solution a plurality of times at regular measurement intervals and outputting a replenishment command for necessary components according to the measured ion concentrations of various components; δ−
Compare multiple ion concentration measurements in one regular period,
When a substantially consistent 1111 constant value is found, the measured value checking means determines that the 1111 constant value is the correct ion concentration measurement value of the nutrient solution, and provides the control means with the ion concentration δP1 constant value; and component adjusting means for replenishing the necessary components into the nutrient solution according to a replenishment command from the control means.

The hydroponic cultivation apparatus according to claim 2 of the present invention includes an ion meter that measures the ion concentration of various components contained in the plant cultivation nutrient solution, and the ion meter measures the ion concentration of the nutrient solution at regular intervals, a control means for outputting a replenishment command for necessary components in accordance with measured values of ion concentrations of various components; ion concentration average value calculation means for calculating a moving average over the measurement period and providing the results to the control means as regular ion concentration measurement values of various components; and a component adjusting means for replenishing the nutrient solution.

The hydroponic cultivation apparatus according to claim 3 of the present invention includes: an ion meter that measures the ion concentration of various components contained in a plant cultivation nutrient solution; A control means for controlling the ion concentration of +1.11 constant and outputting a replenishment command for necessary components according to the measured ion concentration values of various components, and comparing the ion concentration measurement values of multiple times at each +111 constant period from the ion meter. and a measured value checking means that determines and outputs the measured value as a correct ion concentration measurement value of the nutrient solution when a nearly coincident measured value is found, and each measurement period from the lIp + constant value checking means. Each time we receive correct ion concentration measurements for various components,
A-1 Calculate the moving average over multiple AN regular cycles going back to the regular cycle ° period, and use the results as the normal ion concentration f of various components.
The ion concentration average value calculation means is provided as an ill constant value to the control means, and the component adjustment means is configured to replenish the necessary components into the nutrient solution according to a replenishment command from the control means.

(Function) In the hydroponic cultivation apparatus according to claim 1 of the present invention, the ion meter, which is a precision device, may exhibit an abnormal value in the ion concentration δP1 constant value of various components of the nutrient solution due to the contamination of a small amount of dirt or air bubbles. Therefore, when measuring ion concentration at regular intervals, ion concentration measurements are repeated multiple times.

Then, the measurement value checking means checks the ion concentration measurement values that are repeatedly performed as the ion concentration measurement values in each JPJ regular cycle, and checks the measurement values that almost match, and controls the measurement values as the correct ion concentration measurement values in the measurement cycle. Give to the means.

The control means compares the correct ion concentration measurement value from the measurement value checking means with a predetermined comparison value, and when a deficient component is found, outputs a replenishment command for that component to the component adjustment means.

The component adjusting means replenishes the necessary components into the nutrient solution based on the component replenishment command from the control means, and constantly maintains the various nutritional components of the nutrient solution at a composition suitable for the plants being cultivated.

In the hydroponic cultivation apparatus according to claim 2 of the present invention, the ion concentration of various components in the nutrient solution is intermittently and continuously determined at regular intervals using an ion meter, and the average value of the ion concentration is calculated for the measured values. The means goes back for a predetermined period from the 7111 regular time, calculates a moving average of the ion concentration measurement values for each cycle during that period, and provides this to the control means as a regular ion concentration measurement value.

The control means compares the regular ion concentration measurement value from the ion concentration average value calculation means with the comparison value for each predetermined ion, determines the excess or deficiency of various components, and determines the excess or deficiency of various components. A replenishment command is given to the component adjusting means to replenish the component.

Therefore, the component adjusting means replenishes the necessary components into the nutrient solution based on the replenishment command from the control means, and constantly maintains the various component compositions of the nutrient solution to be optimal for the plants being cultivated.

In the hydroponic cultivation apparatus according to claim 3 of the present invention, among the ion concentration measurement values that are repeatedly measured as ion concentration δ-1 constant values of various components in each cycle as in the hydroponic cultivation apparatus according to claim 1, the The measured value obtained is used as the correct ion concentration measurement value for that period.

Then, as in the hydroponic cultivation apparatus of claim 2, for each cycle, a moving average of the ion concentration measurement values for a certain period of time dating back to that cycle is calculated, and this is used as the regular ion concentration measurement value to the control means. The control means determines the excess or deficiency of various components in the nutrient solution based on this ion concentration measurement value, and determines whether there is a deficiency in the various components in the nutrient solution. and gives the supply command to the component adjustment means.

Therefore, the component adjusting means replenishes the necessary components into the IL solution based on the replenishment command from the control means, and always maintains the component composition of the nutrient solution to be optimal for the plants being cultivated.

(Example) Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

Fig. 1 is an F/I diagram of a general hydroponic plant applied to the hydroponic cultivation apparatus according to claims 1 to 3 of the present invention, and shows the same parts as the system shown in Fig. 5. The same reference numerals are used to indicate the structure. Although not shown in FIG. 5, the nutrient solution 3 containing the nutrients necessary for the growth of the plants 7 is fed from a concentrated stock solution tank 18, 19 installed in the house 1 at a flow rate adjusted. valve 2
A predetermined amount of 01i is added to the nutrient solution tank 4 through 0゜21.
They are now being paid.

The nutrient solution 3 stored in the nutrient solution tank 4 should be adjusted to have various nutrient compositions that vary depending on the type of plant 7, its growth stage, sunlight, temperature, humidity, time of day, etc., as will be described later. This component composition adjustment is performed through control.

The nutrient solution 3 from the nutrient solution tank 4 is supplied to the plant bed 2 by a pump 5, where nutrients are supplied to the cultivated plants 7, and the excess nutrient solution 3 is returned to the nutrient solution tank 4.

Reference numeral 22 denotes an ion meter system, which includes the ion meter 11, calibration liquid tanks 13, 14, sampling tank 16, drain tank 17, and printer 12 in FIG.

The controller 23 is connected to the ion meter system 22, and performs ion concentration measurement control for the ion meter system 22, data collection of ion concentration measurement values, and valve opening/closing control of the flow rate adjustment valves 20 and 21 as component adjustment devices. be.

FIG. 2 shows a detailed configuration of the controller 23 of the hydroponic cultivation apparatus according to claim 1 of the present invention, which gives an ion concentration measurement command to the ion meter system 22 and measures the ion concentration of the nutrient solution components, for example. A measurement control unit 24 that performs repeated measurements periodically every hour, and multiple times (usually twice, and once more when an abnormal value is detected) in each cycle, and a measurement control unit 24 that repeatedly measures the measurement every hour, and each cycle repeatedly (usually twice, and once more when an abnormal value is detected), and the ion meter system 22. The measurement value memory 25 stores ion measurement value data.

Further, there is also a comparison calculation section 26a that matches the measured values of multiple times in each cycle and uses the A-1 constant value as the correct ion concentration measurement value when a nearly matching measurement value is obtained, and this comparison calculation section 26a. Based on the ion concentration measurement value determined by the ion concentration measurement value, determine the excess or deficiency of various components by comparing it with the nutrient solution component composition required by the plant 7, calculate the missing component from this ion concentration measurement value, and replenish it. It also includes a concentration control section 27 that outputs commands.

This replenishment command from the concentration control section 27 is sent to the component adjustment device 28.
Flow m adjustment valve 2 which is given to
This controls the opening and closing of a valve of 0.21.

The stock solution tank 18 stores a fertilizer solution containing a large amount of, for example, K4°NO,-, and the other stock solution tank 19 stores a fertilizer solution containing a large amount of, for example, Ca'' and NO,-. Make sure the solution is pooled.

Next, the operation of the hydroponic cultivation apparatus having the above configuration will be explained.

The ion meter system 22 is given a measurement command from the measurement control unit 24 of the controller 23 at regular intervals, for example every hour, and the ion meter system 22 determines the concentration of various ions in the nutrient solution 3 based on this δ-1 constant command. When performing the measurement, it is repeated several times at a time, and the n1 constant value is given to the measured value memory 25, where the measured value is stored.

The comparison calculation section 26g matches the ion concentration measurement values obtained multiple times in each measurement cycle, and if the measurement values are approximately constant, the concentration control section 26g determines that constant value as the correct measurement value.
Give to 7. In addition, if a consistent Δ-1 constant value cannot be obtained after two measurements, an additional one-time ion concentration measurement command is given to the measurement control unit 24, and the ion meter system 22 performs the ion concentration measurement again. and compare that ion concentration measurement value with the previous ion concentration measurement value,
The 111 constant value that matches is given to the concentration control section 27 as the correct measurement value.

In addition, here, it is set to repeat the Al1 constant 2 times in each cycle (7), but it is set to repeat the measurement 3 times from the beginning, and the positive L2 and 1llll constant values are approximately equal to 1. A value measured twice or more may be adopted as a correct measurement value.

Based on the obtained correct ion concentration measurement value, the concentration control unit 27 compares the component composition of the currently required nutrient solution with the ion concentration measurement result according to the growth stage of the currently cultivated plant 7. The flow rate adjustment valve 20. determines whether any component is lacking and, if any component is lacking, can replenish the missing component according to the degree of the shortage.
The appropriate valve 21 is opened for a certain period of time so that the required amount of the stock solution is replenished into the nutrient solution tank 4.

In this way, the ion meter system 22 is made to repeatedly measure the ion concentration multiple times at a predetermined period, find a consistent n1 constant value, and adopt it as the correct ll11 constant value for the period, By adjusting the components of the nutrient solution based on this, even if the ion meter is a precision device and outputs error measurement values due to dirt or air bubbles, accurate ion concentration δP1 constant of various components can be obtained. It can be used to adjust ingredients.

FIG. 3 shows a detailed configuration of the controller 23 used in an embodiment of the hydroponic cultivation apparatus according to claim 2 of the present invention.

In this embodiment, the controller 23 controls the ion concentration level for the ion meter system 22. ! -1 A measurement control unit 24 that controls the constant operation, a measurement value memory 25 that sequentially stores the ion concentration measurement values from the ion meter system 22, and a measurement value memory 25 that sequentially stores the ion concentration measurement values from the ion meter system 22, and the ion concentration Moving average calculation unit 26b that calculates a moving average
and a concentration control section 27 that performs component adjustment control of the nutrient solution based on the measured ion concentration values of each component obtained by the moving average calculation section 26b.

In addition, in the case of this embodiment, the ion meter system 2
2 is not limited to the one using the ion-selective 7Ii electrode shown in Fig. 5, but the ion concentration of each nutrient solution component is δ-! There is no particular limitation as long as it is a device that can be used. Furthermore, the nutrient solution components are not limited to the three types mentioned above, and more components may be used. A measuring device will be used.

Next, this! The operation of the I-liquid cultivation apparatus will be explained.

The lung 1 constant control unit 24 of the controller 23 instructs the ion meter system 22 to measure the ion concentration of each component in the nutrient solution 3 at regular intervals.
are K” and Ca” in the nutrient solution.

The concentration of ions such as NO3- is individually determined 1111. The localization is stored in the measurement value memory 25.

In addition, each time a new measurement value is input to the measurement value memory 25 in each cycle, the moving average calculation unit 26b calculates ions for three times for a certain period of time, for example, 3 hours, from the measurement cycle. A moving average is calculated for the measured concentration values, and this is output to the concentration control section 27 as the regular ion concentration of the nutrient solution.

The concentration control unit 27 compares each ion concentration measurement value with ion concentration comparison values corresponding to various component compositions necessary for the plant based on the calculation results from the moving average calculation unit 26b to determine whether any components are missing. judge whether

When a shortage is found in any component, the concentration control unit 27 opens either or both of the flow rate regulating valves 20 and 21 as the component adjusting device 28 for a necessary time in order to replenish that component. A command is output to supply the required amount of stock solution 18 or 19 to the nutrient solution tank 4.

The reason why the nutrient solution components are adjusted using the moving average of the measured ion concentration values is as follows.

In other words, plants require different nutrients depending on their growth stage, and the nutrients they absorb during the day are different depending on whether there is sunlight or at night, and once absorbed, they may be expelled into the nutrient solution. Therefore, the various components in the nutrient solution fluctuate around the clock, and if you judge the excess or deficiency of various components based on a single ion concentration measurement value, you may not be able to grasp the correct component composition. It is. Moreover, since the target is plants, the reduction of specific components in the nutrient solution does not occur suddenly, and even gradual control can be sufficiently followed.

Therefore, at the ion concentration 71P1 fixed time for each period, by going back for a certain period from the δP1 fixed period and taking the moving average of the ion concentration + 1! By doing so, it becomes possible to manage ingredients more realistically.

FIG. 4 shows an embodiment of the hydroponic cultivation apparatus according to claim 3 of the present invention, and in this embodiment, the ion meter system 22
An apparatus using an ion-selective electrode is used as a device, and the controller 23 includes a comparison calculation section 26a shown in the embodiment of claim 1 and a moving average calculation section 26b shown in the embodiment of claim 2. We are preparing together.

In this hydroponic cultivation device, the A? of the controller 23? The constant control unit 24 issues a measurement command to the ion meter system 22 to repeatedly perform two measurements in each cycle at a constant cycle. Then, the δ-1 constant value memory 25 sequentially stores the ion concentration measurement values from the ion meter system 2'2.

First, the comparison calculation unit 26a operates the al constant value memory 25
Based on the data, it is determined whether or not the two measurement data in each period are substantially the same, and when they match, the ion measurement value is stored in the measurement value memory 25 as the correct ion measurement value in that period.

When the two measurement results do not match, the measurement control unit 23 is made to perform one more ion concentration measurement, and the measurement result is compared with the previous two measurement results,
The "j" constant value that almost matches is stored in the measured value memory 25 as the correct measured value.

In the moving average calculation unit 26b, the comparison calculation unit 26a
Regarding the correct ion concentration -1 constant value found by , each ion concentration measurement value is retrieved from the measurement value memory 25 from the current measurement period to, for example, the three previous 11? The average is calculated and the obtained result is given to the ion concentration control section 27 as a regular ion concentration measurement value for the period.

The concentration control unit 27 compares the obtained ion concentration 'A-1 constant value with a predetermined comparison value in the same manner as in claims 1 and 2 to find out the missing component, and then controls the component adjustment device. The component adjustment command is given to 28.

In this way, multiple N? Find the measured value that agrees with the I constant value as the correct measured value, and calculate the normal value for each cycle by taking the moving average of the measured values going back for a certain period of time based on the obtained correct 4-[constant value. Since the measured value of ion concentration is used for component adjustment, it is possible to extremely accurately control component adjustment based on the ion concentration Δ-1 constant in the nutrient solution.

In this embodiment, the measurement control unit 24 repeats the ion concentration measurement three times in each measurement period, and
A measurement value that matches more than once may be determined to be a correct measurement value. Further, the period to be traced back for each cycle is not particularly limited, and can be changed as appropriate depending on the type of plant to be cultivated, the length of the measurement cycle, the scale of the entire plant, etc.

Furthermore, in the embodiments of each of the claims above, the flow rate adjustment valves 20 and 21 for adjusting the flow rate of the stock solution were used as the component adjustment device 28 for adjusting the nutrient solution components, but
There is no particular limitation on the means as long as it is possible to control the supply amount of the stock solution, and a metering pump may also be used.

Furthermore, the stock solution is not limited to two types, and control using more types is also possible.

[Effects of the Invention] As described above, according to the hydroponic cultivation apparatus of claim 1 of the present invention, when adjusting the components by determining the ion concentration and IN of various components in the nutrient solution, The ion concentration measurements are repeated multiple times, and the measured values that are consistent with each other are used as the correct ion concentration measurement values, so even if a precision ion meter is contaminated with dust or air bubbles that may cause false detection, Component control can be performed by accurately measuring ion concentration.

Further, according to the hydroponic cultivation apparatus of claim 2, the ion concentration of the nutrient solution is periodically measured using an ion meter, and a moving average is taken of the ion concentration measurement values for a certain period going back to that cycle for each cycle. It is used to adjust the nutrient solution components as a measured value of ion concentration during a cycle, so the components absorbed by the plant at a certain time are expelled at the next time, so that the component composition in the nutrient solution increases or decreases over time. Even in such cases, the components can be adjusted based on the average component composition, and more appropriate component adjustments can be made.

Furthermore, in the hydroponic cultivation apparatus according to claim 3 of the present invention, measurements are repeated multiple times for each measurement cycle, and the measurement values that are consistent are regarded as the correct measurement values for the measurement cycle, and the n1 constant value for each measurement cycle is The moving average of multiple correct measurements obtained during a certain period of time back from the cycle is taken, and this is used as the regular ion concentration measurement value for the measurement cycle for component control, so ion concentration measurement for each measurement cycle is performed. In addition to obtaining an accurate value of 1q, it is possible to adjust the components based on the average component composition even for component compositions that vary over time, and it is possible to perform accurate and appropriate component adjustments in accordance with reality.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the hydroponic cultivation apparatus according to claim 1 of the present invention, FIG. 2 is a block diagram showing the detailed configuration of the controller in the embodiment of claim 1, and FIG. FIG. 4 is a block diagram showing the detailed configuration of the controller of the hydroponic cultivation apparatus according to claim 2 of the invention, FIG. 4 is a block diagram showing the detailed configuration of the controller of the hydroponic cultivation apparatus according to claim 3 of the invention, and FIG. It is a plant explanatory diagram of a typical hydroponic cultivation device. 2... Hydroponic bed 3... Nutrient solution 4...
Nutrient solution tank 5... Pump 7... Plant 15... Sampling pump 18.19... Stock solution tank 0, 21... Flow rate adjustment valve 22... Ion meter system 23... Controller 24. ...Δ-1 constant control section 25... Measured value memory 26a... Comparison calculation section 2
6b...Moving average calculation section

Claims (3)

[Claims] (1) An ion meter that measures the ion concentration of various components contained in a plant cultivation nutrient solution, and the ion meter repeatedly measures the ion concentration of the nutrient solution multiple times at a fixed measurement cycle, a control means that outputs a replenishment command for necessary components according to the measured ion concentration of the ion meter, and a plurality of ion concentration measurements from the ion meter in each measurement period are compared, and measurement values that are almost in agreement are found. a measured value checking means for determining that the measured value is a correct ion concentration measurement value of the nutrient solution and supplying the ion concentration measurement value to the control means; A hydroponic cultivation device comprising a component adjusting means for replenishing a nutrient solution. (2) An ion meter that measures the ion concentration of various components contained in the plant cultivation nutrient solution; The ion meter measures the ion concentration of the nutrient solution at regular intervals, and determines the necessary components according to the measured ion concentrations of the various components. a control means for outputting a replenishment command for the ion meter; and a control means for calculating a moving average over a plurality of measurement cycles going back to the measurement cycle each time the ion concentration measurement values of various components are input from the ion meter for each measurement cycle. , an ion concentration average value calculation means that provides the results as regular ion concentration measurement values of various components to the control means, and a component adjustment means that replenishes the necessary components into the nutrient solution according to a replenishment command from the control means. A hydroponic cultivation device comprising: (3) An ion meter that measures the ion concentration of various components contained in a plant cultivation nutrient solution; The ion meter repeatedly measures the ion concentration of the nutrient solution multiple times at a fixed measurement cycle, and a control means that outputs a replenishment command for necessary components according to the measured ion concentration of the ion meter, and a plurality of ion concentration measurements from the ion meter in each measurement period are compared, and measurement values that are almost in agreement are found. a measured value checking means that determines and outputs the measured value as a correct ion concentration measurement value of the nutrient solution; , ion concentration average value calculation means for calculating a moving average over a plurality of measurement periods dating back to the measurement period and providing the results to the control means as regular ion concentration measurement values of various components; A hydroponic cultivation apparatus comprising a component adjusting means for replenishing the nutrient solution with the necessary components according to a replenishment command.