JP2017023058A - Culture medium supplying apparatus and culture medium preparing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a culture medium supplying apparatus and a culture medium preparing method, which can accurately correct the mixing amount of a liquid fertilizer and improve the accuracy of adjusting the characteristics of the culture medium.SOLUTION: The culture fluid supply device 1 of the present invention comprises: a solenoid valve 43 in a liquid fertilizer supply pipe 42; a liquid fertilizer supply pipe 44 disposed between the solenoid valve 43 and a liquid fertilizer tank 41; and a liquid fertilizing return pipe 45 that connects the liquid fertilizing tank 41 to a middle pipe portion 42a located between the solenoid valve 43 and the liquid fertilizer supply pump 44. During the fertilization time of the culture medium to a plant, therefore, driving of the liquid fertilizer supply pump 44 can be continued at either timing of opening and closing the electromagnetic valve. Immediately after the solenoid valve 43 switches from the closed state to the open state, the liquid fertilizer flows toward the culture solution tank 10. There is no time lag in supplying liquid fertilizer toward the culture solution tank 10. Thus, the amount of liquid fertilizer can be precisely controlled.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a culture solution supply apparatus and a culture solution preparation method for supplying a plant grown in a greenhouse or the like as a culture solution prepared by mixing liquid fertilizer and water to have predetermined characteristics.

  As a culture solution supply apparatus that mixes liquid fertilizer with water to make a culture solution and supplies it to a plant cultivation area, those disclosed in Patent Documents 1 and 2 are known. In Patent Document 1, water supplied from a raw water supply system and liquid fertilizer supplied from a liquid fertilizer supply system are mixed in a liquid supply tank (culture liquid tank) to prepare a culture solution having a predetermined concentration in the culture liquid tank. The structure which supplies this culture solution to the cultivation area | region of a plant is disclosed. Here, the concentration of the culture solution is determined so that a predetermined concentration is obtained according to the flow rate of the water in the raw water supply system by disposing a metering pump between the stock solution tank holding the stock solution of liquid fertilizer and the culture solution tank. This is done by controlling the pump drive. For example, when the metering pump is a DC motor pump, the mixing amount of the liquid fertilizer stock solution is controlled to be a predetermined amount corresponding to the amount of water by the number of rotations.

  In Patent Document 2, an electromagnetic valve is provided in a liquid fertilizer supply pipe connecting the stock solution tank and the culture solution tank, and a circulation pipe and a circulation pump are provided in the culture solution tank in order to perform a function of mixing and stirring the culture solution. The liquid fertilizer supply pipe is connected to this circulation pipe. The culture fluid circulates through the circulation pipe by the operation of the circulation pump. However, when the electromagnetic valve of the liquid manure supply pipe is opened, the liquid fertilizer is sucked from the stock tank to the circulation pipe side by negative pressure.

JP 2007-228801 A Japanese Patent Publication No. 3-1937

  In the case of the device disclosed in Patent Document 1, the amount of liquid fertilizer to be mixed is adjusted by drive control of a metering pump. However, when liquid fertilizer is mixed, since the metering pump is driven from a stopped state, a time lag corresponding to the rising time of the metering pump occurs. Therefore, there is a problem in terms of adjustment accuracy of the concentration of the culture solution. Since the apparatus disclosed in Patent Document 2 is also configured to suck liquid manure by negative pressure, the suction amount is not stable, and it is difficult to accurately adjust the concentration. In Patent Document 2, a circulation pipe and a circulation pump are provided as stirring means for uniformizing the concentration distribution of the culture solution in the culture solution tank. However, the structure is complicated and the cost is increased.

  The present invention has been made in view of the above, and can adjust the characteristics including the concentration of the culture solution with higher accuracy than before, and can further promote stirring in the culture solution tank while having a simple structure. It is an object to provide a culture solution supply apparatus and a culture solution preparation method.

  In order to solve the above-described problems, the culture solution supply device of the present invention is a culture solution supply device including a culture solution tank in which a culture solution obtained by mixing water and liquid fertilizer for fertilizing a plant is stored. The liquid fertilizer supply mechanism that supplies the liquid fertilizer to the culture liquid tank is stored in the liquid fertilizer tank that stores the liquid fertilizer, a liquid fertilizer supply pipe that connects the liquid fertilizer tank and the culture liquid tank, and the culture liquid tank An electromagnetic valve provided in the liquid fertilizer supply pipe that is controlled to be opened and closed based on data relating to characteristics including the concentration of the culture liquid, and provided between the liquid fertilizer tank and the electromagnetic valve in the liquid fertilizer supply pipe. A liquid fertilizer supply pump that continues to be driven at the timing of opening and closing of the solenoid valve during fertilization time, and a midway pipe section in the liquid fertilizer supply pipe between the solenoid valve and the liquid fertilizer supply pump; Characterized by comprising a pipe returning a liquid fertilizer connecting said liquid fertilizer tank.

The liquid fertilizer supply pipe further includes a feed adjustment valve provided between the electromagnetic valve and the culture liquid tank, and a return adjustment valve provided in the liquid fertilizer return pipe, and the liquid fertilizer when the electromagnetic valve is opened. It is preferable to control the supply amount of the liquid manure supplied from the supply pipe to the culture medium tank by adjusting both the feed adjustment valve and the return adjustment valve.
The water supply pipe for supplying the water to the culture medium tank has a water supply port disposed in a direction substantially along the peripheral wall part of the culture medium tank, and is substantially along the peripheral wall part of the culture medium tank by water supply. It is preferable that the swirl flow is generated in the direction.

A culture solution delivery mechanism for delivering the culture solution from the culture solution tank to the culture solution fertilizer, a culture solution delivery pipe connecting the culture solution tank and the culture solution fertilizer, and a culture solution delivery tube; The culture solution delivery pump for delivering the culture solution from the culture solution tank, a midway pipe portion in the culture solution delivery tube and the culture solution tank are connected, and a return port is provided in the culture solution tank. A culture solution return pipe that is arranged in a direction substantially along the peripheral wall portion and that causes a swirling flow in a direction substantially along the peripheral wall portion of the culture solution tank by the culture solution returned from the return port. Preferably there is.
A suction portion provided at one end of the culture medium delivery tube and disposed in the culture medium tank for sucking the culture medium has a predetermined length along a substantially radial direction of the culture medium tank, and the suction It is preferable that a plurality of suction ports are provided in the portion along the substantially radial direction, or a long and long suction port is provided along the substantially radial direction.

  Moreover, the culture solution preparation method of the present invention is a culture solution preparation method in which the liquid fertilizer is diluted with water in a culture solution tank and the culture solution to be supplied to the plant is prepared to have a predetermined property. As a liquid fertilizer supply mechanism for supplying to the tank, an electromagnetic valve provided in a liquid fertilizer supply pipe connecting the liquid fertilizer tank for storing the liquid fertilizer and the culture liquid tank, and a liquid fertilizer supply pump provided between the liquid fertilizer tank and the electromagnetic valve And the liquid fertilizer supply pipe connecting the intermediate portion of the liquid fertilizer supply pipe between the solenoid valve and the liquid fertilizer supply pump and the liquid fertilizer tank, and during the fertilization time of the culture solution, the liquid fertilizer The supply pump is continuously driven. When the electromagnetic valve is opened, the liquid fertilizer is supplied to the culture tank through the liquid fertilizer supply pipe. When the electromagnetic valve is closed, the liquid fertilizer is supplied to the liquid tank through the liquid fertilizer return pipe. By returning the serial liquid fertilizer, which comprises preparing a culture of said predetermined characteristic by opening and closing control of the solenoid valve.

  The culture solution supply apparatus of the present invention includes an electromagnetic valve in the liquid fertilizer supply pipe, a liquid fertilizer supply pump between the electromagnetic valve and the liquid fertilizer tank, and further, a midway pipe portion between the electromagnetic valve and the liquid fertilizer supply pump and the liquid fertilizer tank Liquid fertilizer return pipe connecting Therefore, during the fertilization time of the culture solution to the plant, the driving of the liquid fertilizer supply pump can be continued at any timing when the electromagnetic valve is opened and closed. That is, liquid fertilizer is naturally supplied to the culture tank when the solenoid valve is opened, but liquid fertilizer sucked by the liquid fertilizer supply pump is returned to the liquid fertilizer tank when the solenoid valve is closed. Therefore, as soon as the solenoid valve is switched from the closed state to the open state, liquid fertilizer flows to the culture tank side, there is no time lag when supplying liquid fertilizer to the culture tank side, It is not necessary to turn the liquid fertilizer supply pump on and off as in Patent Document 1 for adjustment. Since it can be adjusted only by switching control of the solenoid valve, the amount of liquid fertilizer mixed can be accurately controlled, and the adjustment accuracy of the characteristics (concentration, pH, etc.) of the culture solution is improved.

  Moreover, it is preferable that the culture solution supply apparatus of this invention arrange | positions the water supply port of a water supply pipe | tube toward the direction which substantially follows the surrounding wall part in a culture solution tank. Furthermore, it is preferable that the return port of the culture solution return pipe connected to the culture solution delivery pipe is similarly arranged in a direction substantially along the peripheral wall portion in the culture solution tank. As a result, the swirling flow can be generated in the culture solution stored in the culture solution tank at the time of water supply or at the time of fertilization of the culture solution, and the culture solution can be easily and at low cost without providing a dedicated stirring means. Can be stirred. Further, the culture medium suction section provided in the culture medium delivery pipe has a predetermined length along the substantially radial direction of the culture medium tank, and a plurality of suction ports are provided in the suction section along the substantially radial direction. Alternatively, it is preferable that a long slot-like suction port is provided along the substantially radial direction. Thereby, the culture solution can be sucked from a wide range, and it is effective for suppressing unevenness of characteristics (concentration, pH, etc.) of the culture solution to be fertilized.

FIG. 1 is a diagram showing an overall configuration of a culture solution supply apparatus according to an embodiment of the present invention. FIG. 2 is a plan view showing main parts of the culture solution tank, the water supply mechanism, and the culture solution delivery mechanism of the culture solution supply apparatus according to the embodiment. FIG. 3 is a perspective view showing essential parts of a culture solution tank, a water supply mechanism, and a culture solution delivery mechanism of the culture solution supply apparatus according to the embodiment.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. FIG. 1 is a diagram illustrating an overall configuration of a culture solution supply apparatus 1 according to the present embodiment. As shown in this figure, the culture solution supply apparatus 1 of this embodiment includes a culture solution tank 10, a water supply mechanism 20, a culture solution delivery mechanism 30, a liquid fertilizer supply mechanism 40, and a controller 50.

  The culture medium tank 10 has, for example, a substantially cylindrical shape, and stores a predetermined amount of culture medium inside. The volume of the culture medium tank 10 is not limited, but it is preferable to use a relatively small capacity type of about 100 to 500 liters. As this type of culture medium tank, a tank of 1000 liters or more is often used. However, in addition to a large installation space, it takes a long time to prepare the culture medium. On the other hand, in the case of a small-capacity type, the installation space can be made narrower and the preparation time of the culture solution is short. Therefore, for example, by making fertilizer while preparing the culture solution in the culture solution tank 10, Necessary fertilizer can be secured without placing. However, in the case where the preparation of the culture solution and the fertilization are simultaneously performed in this way, it is difficult to adjust characteristics such as the concentration and pH of the culture solution in the culture solution tank 10, but according to the present embodiment, even in such a case, As described later, the characteristics of the culture solution can be adjusted with high accuracy.

  The water supply mechanism 20 has a water supply pipe 21 having one end connected to a water supply source and a water supply port 21a at the other end facing the culture medium tank 10, and a water supply pump 22 for supplying water from the water supply source to the water supply pipe 21. Configured. In this embodiment, as shown in FIGS. 2 and 3, the water supply port 21a of the water supply pipe 21 is preferably located as close to the bottom wall 10a as possible in the culture solution tank 10, and the opening direction thereof is cultured. In this embodiment, since the culture solution tank 10 has a substantially cylindrical shape so as to be in a direction substantially along the peripheral wall portion 10b of the solution tank 10, it is arranged toward one side along the substantially circumferential direction. As a result, when the water in the culture solution tank 10 is discharged from the water supply port 21a, a swirl flow is formed in the direction of the arrow in FIG. 2, and the culture solution tank 10 is not provided with a dedicated stirring means. Agitation of the stored culture solution can be promoted.

  The culture solution delivery mechanism 30 includes a culture solution delivery pipe 31, a culture solution delivery pump 32, and a culture solution return pipe 33. The culture solution delivery tube 31 has one end connected to the culture solution tank 10 and the other end connected to the culture solution fertilizer. The culture liquid fertilizer is a watering nozzle, a drip tube, a watering tube (Everflow, etc.) provided in the plant cultivation area, and the culture liquid that has passed through the culture liquid delivery pipe 31 passes through these culture liquid fertilizers to the cultivation area. Fertilized.

  As shown in FIGS. 2 and 3, a culture solution suction part 31 a is provided at one end of the culture solution delivery pipe 31. In the present embodiment, the culture solution delivery tube 31 is disposed through the portion of the peripheral wall portion 10b of the culture solution tank 10 near the bottom wall portion 10a, and the suction portion 31a is provided at the end thereof. Normally, the opening at one end of the culture solution delivery tube 31 is allowed to function as a suction port as it is, but in this embodiment, a suction part 31 a having a predetermined length is connected to one end of the culture solution delivery tube 31. A range of a predetermined length of the tube wall near one end of the culture solution delivery tube 31 may be used as the suction part 31a. In any case, the suction part 31a has a predetermined length along the substantially radial direction of the culture medium tank 10, and the suction part 31a through which the culture medium is sucked is provided in the suction part 31a.

  In the present embodiment, a plurality of suction ports 31b having an arbitrary shape such as a circular shape, a polygonal shape, and a long hole shape are formed along the substantially radial direction of the culture medium tank 10 that is the longitudinal direction of the suction portion 31a. It consists of holes. Due to the suction from the plurality of suction ports 31b, the culture solution can be taken in from the predetermined range in which the suction ports 31b are formed in the culture solution tank 10 without being concentrated from one specific place, and stored. Even when the agitation of the culture medium is insufficient and the characteristics such as concentration and pH are not uniform, the culture medium fertilized from the culture liquid fertilizer through the culture liquid delivery tube 31 by taking the culture liquid from a wider range Unevenness of liquid characteristics can be suppressed. The suction port 31b that performs such a function may be composed of one or more elongated holes having a predetermined length in the substantially radial direction, in addition to a structure in which a plurality of suction ports 31b are provided along the substantially radial direction of the culture medium tank 10. It is.

  The culture solution delivery pump 32 is interposed in the culture solution delivery tube 31 and is activated, for example, when a predetermined set time is reached. The culture solution is sent from the culture solution tank 10 to the culture solution delivery tube 31 and supplied from the culture solution fertilizer. Let The culture solution return pipe 33 is connected to the culture solution tank 31 so as to connect the midway pipe portion 31 c located in front of the culture solution delivery pump 32 in the culture solution delivery pipe 31 to the culture solution tank 10. I do. When the pressure on the side of the culture solution fertilizer relative to the culture solution delivery pump 32 is equal to or higher than a predetermined value, the culture solution is refluxed through the culture solution return pipe 33. As shown in FIGS. 2 and 3, the culture solution return pipe 33 passes through the upper end of the culture solution tank 10 and is located near the bottom wall portion 10 a in the peripheral wall portion 10 b and has a return opening 33 a that is an end opening thereof. Is disposed so as to be positioned. At this time, the return port 33a is preferably arranged in a direction substantially along the peripheral wall portion 10b of the culture medium tank 10. A swirling flow in a direction substantially along the peripheral wall portion of the culture medium tank can be generated by the culture medium returned from the return port 33a, and agitation of the culture medium stored in the culture medium tank 10 can be promoted.

  However, considering that the discharge of water from the water supply port 21a of the water supply pipe 21 and the discharge of the culture solution from the return port 33a of the return pipe 33 for culture solution may be performed at the same timing, FIG. As shown, the water supply port 21a and the return port 33a are preferably directed in the same direction, so that the generated swirl flow becomes clearer and larger, and stirring of the culture solution can be promoted.

  In addition, when the storage amount of the culture solution in the culture solution tank 10 is full, either the culture solution discharged from the return port 33a of the culture solution return pipe 33 or the water discharged from the water supply port 21a of the supply water pipe 21 is used. Although the above swirl flow is less likely to occur, the suction port 31b of the culture solution delivery tube 31 of the present embodiment has a structure that can take in the culture solution from a wide range as described above. Even in a state where it is difficult to occur, it is effective in suppressing unevenness in the characteristics of the culture solution to be fertilized.

  The liquid fertilizer supply mechanism 40 includes a liquid fertilizer tank 41, a liquid fertilizer supply pipe 42, an electromagnetic valve 43, a liquid fertilizer supply pump 44, and a liquid fertilizer return pipe 45. As shown in FIG. 1, in this embodiment, there are three sets of components such as the liquid fertilizer tank 41 and the like, and the three types of liquid fertilizer are mixed with water. However, the present invention is not limited to this. Each component may be composed of one set or four or more sets, and one type or four or more types of liquid fertilizer may be mixed.

  Each liquid fertilizer tank 41 stores a stock solution of an arbitrary liquid fertilizer. In the present embodiment, one of these liquid fertilizer tanks 41 stores liquid fertilizer (medicine) for pH adjustment, but the type of liquid fertilizer to be stored is arbitrary. One end of a liquid fertilizer supply pipe 42 is connected to each liquid fertilizer tank 41, and the other end of each liquid fertilizer supply pipe 42 is connected to the culture liquid tank 10. The electromagnetic valve 43 is provided for each liquid fertilizer supply pipe 42 and controls the distribution of liquid fertilizer. A liquid fertilizer supply pump 44 is provided in each intermediate pipe portion 42 a between the liquid fertilizer tank 41 and the solenoid valve 43 in each liquid fertilizer supply pipe 42, and a liquid fertilizer return pipe 45 is provided between the intermediate pipe portion 42 a and the liquid fertilizer tank 41. Is arranged. In addition, the code | symbol 46 is a flowmeter provided before the solenoid valve 43 in the midway pipe part 42a.

  Here, each solenoid valve 43 receives a signal from a sensor (conductivity meter, pH sensor, etc.) 11 that measures characteristics such as the concentration (electric conductivity (EC)) and pH of the culture solution in the culture solution tank 10. The signals are supplied to a controller 50 including a computer and are individually controlled based on signals sent from the controller 50. The controller 50 receives information from the sensor and also manages the timing of fertilizing the plant cultivation area. That is, the controller 50 previously inputs characteristic values such as the timing of fertilizing the culture medium within a day, the target concentration of the culture medium to be prepared, pH, and the like, according to the type and season of the crop. Has been.

  Moreover, each liquid manure supply pump 44 drives according to the time which fertilizes a culture solution to a cultivation area | region based on the signal from the controller 50. FIG. In the present embodiment, each liquid fertilizer supply pump 44 is controlled so as to be always driven in this fertilization time zone regardless of whether each electromagnetic valve 43 is opened or closed. Therefore, when each electromagnetic valve 43 is closed, the liquid manure sucked by the liquid manure supply pump 44 is returned to the liquid manure tank 41 via the liquid manure return pipe 45, and an overload to the liquid manure supply pump 44 is prevented. The On the other hand, even when each solenoid valve 43 is opened, all of the liquid fertilizer in each liquid fertilizer tank 41 sucked by each liquid fertilizer supply pump 44 is cultivated from the culture liquid fertilizer through the liquid fertilizer supply pipe 42. A predetermined amount of liquid fertilizer is not applied to the area, and is returned to the liquid fertilizer tank 41 through the liquid fertilizer return pipe 45. Although it may be possible to prepare a culture solution that provides the desired characteristics only by driving each liquid fertilizer supply pump 44 and controlling the opening and closing of each solenoid valve 43, each liquid fertilizer supply pump 44 also has individual differences, and usually it alone. Characteristic control is difficult. Therefore, it is preferable that a feed adjustment valve 47 is provided between each electromagnetic valve 43 and the culture liquid tank 10 in each liquid manure supply pipe 42, and a return adjustment valve 48 is provided in each liquid manure return pipe 45. By setting the opening / closing amounts of the feed adjustment valve 47 and the return adjustment valve 48, the supply amount of liquid fertilizer when each electromagnetic valve 43 is opened can be controlled more accurately.

  According to the present embodiment, when a predetermined fertilization time is reached by a command from the controller 50, the culture solution delivery pump 32 is driven and adjusted to predetermined characteristics (concentration, pH, etc.) in the culture solution tank 10. The existing culture solution is supplied from the culture solution fertilizer to the cultivation area via the culture solution delivery pipe 31. The culture solution that has not been supplied to the culture solution fertilizer due to the pressure of the culture solution delivery pump 32 or the like is returned from the return port 33a to the culture solution tank 10 through the culture solution return pipe 33. Since the opening direction is the direction along the peripheral wall portion 10b of the culture solution tank 10, a swirling flow is generated in the same direction, and the culture solution stored in the culture solution tank 10 is agitated.

  However, it is preferable that the culture medium in the culture medium tank 10 is usually set so that it does not remain so much when the previous fertilization is completed. Therefore, the feed water pump 22 is almost at the same time as the culture medium delivery pump 32 starts to operate. Is driven, and water is supplied from the water supply port 21 a of the water supply pipe 21. Since the water supply port 21a faces in the direction along the peripheral wall portion 10b of the culture solution tank 10, a swirling flow is generated in the culture solution in the culture solution tank 10 by water supply, and further agitation is promoted.

  On the other hand, when the predetermined fertilization time is reached and the culture solution delivery pump 32 is driven, the liquid fertilizer supply pumps 44 are also driven at substantially the same timing. When each electromagnetic valve 43 is closed, the liquid manure sucked from each liquid fertilizer tank 41 by each liquid fertilizer supply pump 44 is returned to each liquid fertilizer tank 41 through each liquid fertilizer return pipe 45. In this state, when water is supplied from the water supply pipe 21 as described above, and data related to characteristics such as the concentration and pH of the culture solution in the culture solution tank 10 is sent from the sensor 11 to the controller 50, a predetermined electromagnetic wave is generated accordingly. The valve 43 is opened. When the predetermined electromagnetic valve 43 opens, the liquid fertilizer sucked by the liquid fertilizer supply pump 44 corresponding to the electromagnetic valve 43 is supplied to the culture liquid tank 10 through the liquid fertilizer supply pipe 42. As described above, since the flow rate of the liquid fertilizer passing through the liquid fertilizer supply pipe 42 is determined by the setting of the opening / closing amounts of the feed adjustment valve 47 and the return adjustment valve 48, the time during which the electromagnetic valve 43 is kept open is determined. If controlled by the controller 50, it is possible to accurately supply the amount of liquid fertilizer necessary to obtain a culture solution having desired characteristics. Further, since the liquid fertilizer supply pump 44 is operated before the electromagnetic valve 43 is opened, the liquid fertilizer is fed into the liquid fertilizer supply pipe 42 simultaneously with the valve opening, and there is no time lag and an accurate amount can be supplied.

DESCRIPTION OF SYMBOLS 1 Culture liquid supply apparatus 10 Culture liquid tank 11 Sensor 20 Water supply mechanism 21 Water supply pipe 21a Water supply port 22 Water supply pump 30 Culture liquid delivery mechanism 31 Culture liquid delivery pipe 31a Suction part 31b Suction port 31c Midway pipe part 32 Culture liquid delivery pump 33 Culture Liquid return pipe 33a Return port 40 Liquid fertilizer supply mechanism 41 Liquid fertilizer tank 42 Liquid fertilizer supply pipe 42a Intermediate pipe portion 43 Solenoid valve 44 Liquid fertilizer supply pump 45 Liquid fertilizer return pipe 50 Controller

Claims (6)

A culture solution supply apparatus including a culture solution tank in which a culture solution formed by mixing water and liquid fertilizer for fertilizing a plant is stored,
A liquid fertilizer supply mechanism for supplying the liquid fertilizer to the culture liquid tank,
A liquid fertilizer tank for storing the liquid fertilizer;
A liquid fertilizer supply pipe connecting the liquid fertilizer tank and the culture liquid tank;
An electromagnetic valve provided in the liquid fertilizer supply pipe that is controlled to open and close based on data relating to characteristics including the concentration of the culture solution stored in the culture solution tank;
Liquid fertilizer supply pump provided between the liquid fertilizer tank and the electromagnetic valve in the liquid fertilizer supply pipe, and continues to be driven at any time when the electromagnetic valve is opened or closed during the fertilization time of the culture solution When,
A culture liquid supply apparatus comprising: a liquid fertilizer return pipe that connects an intermediate pipe portion of the liquid fertilizer supply pipe between the electromagnetic valve and the liquid fertilizer supply pump and the liquid fertilizer tank. A feed adjustment valve provided between the electromagnetic valve and the culture medium tank in the liquid fertilizer supply pipe;
A return adjustment valve provided in the liquid fertilizer return pipe,
The culture according to claim 1, wherein the supply amount of the liquid fertilizer supplied from the liquid fertilizer supply pipe to the culture liquid tank when the electromagnetic valve is opened is controlled by adjusting both the feed adjustment valve and the return adjustment valve. Liquid supply device.   The water supply pipe for supplying the water to the culture medium tank has a water supply port disposed in a direction substantially along the peripheral wall part of the culture medium tank, and is substantially along the peripheral wall part of the culture medium tank by water supply. The culture solution supply apparatus according to claim 1, wherein the culture solution supply device is configured to generate a swirling flow in a direction. A culture solution delivery mechanism for delivering the culture solution from the culture solution tank to the culture solution fertilizer,
A culture solution delivery pipe connecting the culture solution tank and the culture solution fertilizer;
A culture medium delivery pump that is provided in the culture medium delivery pipe and delivers the culture medium from the culture medium tank;
The medium pipe portion of the culture medium delivery pipe is connected to the culture medium tank, and the return port is disposed in a direction substantially along the peripheral wall of the culture medium tank. The culture solution supply apparatus according to any one of claims 1 to 3, wherein the culture solution supply apparatus has a culture solution return pipe that generates a swirling flow in a direction substantially along the peripheral wall portion of the culture solution tank by the returned culture solution. .   A suction portion provided at one end of the culture medium delivery tube and disposed in the culture medium tank for sucking the culture medium has a predetermined length along a substantially radial direction of the culture medium tank, and the suction The culture solution supply apparatus according to claim 4, wherein the part is provided with a plurality of suction ports along a substantially radial direction, or with a long and long suction port along a substantially radial direction. A culture liquid preparation method for preparing a culture liquid to be supplied to a plant by diluting liquid fertilizer with water in a culture liquid tank,
As a liquid fertilizer supply mechanism for supplying the liquid fertilizer to the culture liquid tank, an electromagnetic valve provided in a liquid fertilizer supply pipe connecting the liquid fertilizer tank storing the liquid fertilizer and the culture liquid tank, and between the liquid fertilizer tank and the electromagnetic valve A liquid fertilizer supply pump provided in the liquid fertilizer supply pipe, and a liquid fertilizer return pipe connecting the liquid fertilizer tank and the intermediate portion of the liquid fertilizer supply pipe between the solenoid valve and the liquid fertilizer supply pump,
During the fertilization time of the culture liquid, the liquid fertilizer supply pump is continuously driven, and when the electromagnetic valve is opened, the liquid fertilizer is supplied to the culture liquid tank through the liquid fertilizer supply pipe, and when the electromagnetic valve is closed, the liquid fertilizer is supplied. A culture liquid preparation method, wherein the liquid fertilizer is returned to the liquid tank through a return pipe to prepare the culture liquid having the predetermined characteristics by opening / closing control of the electromagnetic valve.

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