JPH056977B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to hydroponic cultivation technology implemented as greenhouse horticulture, and in particular to the hydroponic cultivation technology using isolated media. This invention relates to an automatic irrigation control device that automatically controls changes in composition concentration due to accumulation.

[Conventional technology]

In recent years, hydroponic cultivation has become popular in the field of greenhouse horticulture, and recently, hydroponic cultivation using a culture medium has been increasing in particular. In hydroponic culture using a culture medium, it is essential to control the moisture in the culture medium, and if the nutrient solution circulation method is not used, use a moisture sensor or
Irrigation control is performed by estimating the amount of irrigation required using the amount of solar radiation as a guide. Various moisture sensors have been proposed for the purpose of controlling this type of culture medium moisture, but some have insufficient accuracy, are unsuitable for long-term use in culture media, and are not highly accurate. It has disadvantages such as being expensive.

Furthermore, as this type of hydroponic cultivation method, cultivation using rock wool is rapidly becoming popular in recent years.
In this Rockwool cultivation, methods have been proposed, such as indirectly estimating the amount of evapotranspiration based on the amount of solar radiation, or directly measuring the weight of the Rockwool culture medium to control the irrigation of the medium, but each method has its advantages and disadvantages. .

However, among the above methods, the method of controlling irrigation by measuring the amount of evapotranspiration itself is gaining recognition as a relatively superior method. The reason for this is that during crop cultivation, the consumption of medium water is mostly due to transpiration from the crop and evaporation from the medium, and these are dependent on the degree of crop growth and the environment surrounding the crop, such as temperature, humidity, radiant heat, etc. This is because, compared to the above-mentioned indirect measurement and management of medium moisture, it is possible to manage it more easily and accurately since it is influenced by complicated factors.

[Problem to be solved by the invention]

To date, the following two methods have been proposed as methods for directly measuring the amount of evapotranspiration of medium water.

The first method is to lay a capillary mat in a tray of the required size, place a rock wool mat as an artificial culture medium on top of it, and transfer the water held in the tray by the capillary action of the capillary mat. The water is evenly supplied to the Rockwool culture medium by using the tray, and the excess water in the culture medium is collected at the bottom of the tray and then appropriately discharged to the outside. In this case, two electrodes are installed in the water pool of the tray as a water level sensor, and the amount of evapotranspiration of the medium water is detected as a change in the water level in the tray, and this is converted into the amount of water to control the irrigation. conduct.

However, in this method, when setting up a large number of Rockwool culture media, the above configuration is adopted for some of the media, so only the representative culture medium of all the media is constantly trayed for the purpose of detecting evapotranspiration. Because they are supplied with water within the culture medium, they are placed in an environment that is quite different from other culture media, and they have the disadvantage that they are not managed based on representative values for the entire culture medium.

In addition, the second method replaces the tray and capillary mat used in the first method with an independent container and capillary reach tube, and uses the capillary force of the capillary reach tube to transfer the water in the container to rock wool. It is constructed and implemented so that the total amount of irrigation water in the culture medium is collected into a container while supplying it to the culture medium. In this case, the water level in the container is detected by a level sensor, and the displacement is converted into the amount of irrigation as evapotranspiration, and irrigation control is performed.

This method can be implemented at a lower cost than the first method, but since the total amount of water in the container is also exchanged with the culture medium, the amount of evapotranspiration per unit time and the capillary reach tube are If the balance with the capacity is disrupted, there will be problems such as a delay in issuing an irrigation start command, resulting in insufficient water in the culture medium, or a delay in issuing an irrigation stop command, resulting in excess water in the culture medium.

The two methods described above have in common that they both use a mechanism that converts the total amount of evapotranspiration in the culture medium into water level, and uses a level sensor to output ON/OFF signals for irrigation control. However, although these methods directly measure the total amount of evapotranspiration, the total amount of evapotranspiration is exchanged between the sensor and the culture medium. When the water is turned on, the liquid flows into a separate reservoir, and this state is then detected by a level sensor and an OFF signal for irrigation control is output. For this reason, the culture medium used as the sensor mentioned above and the other culture media are in a considerably different environment, and there is a problem in converting the appropriate amount of water to the entire rock wool culture medium. Many issues remain to be resolved in order to realize this.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optional method that can properly and quickly detect changes in the moisture content in a culture medium as changes in water level, and also eliminates the accumulation of fertilizer components caused by repeated fertilization and watering of the culture medium. To provide an automatic irrigation control device that can perform over-irrigation.

[Means to solve the problem]

The automatic irrigation control device according to the present invention is a hydroponic cultivation system that uses a culture medium configured to measure the moisture content of the culture medium and control the irrigation device to maintain the moisture content of the culture medium within a set range. An automatic irrigation system comprising water level detection cylinders that communicate with each other, an electrode for detecting the water level in the water level detection cylinder, and a controller that is controlled by the electrode to control the start and stop of irrigation of the irrigation device. In the control device, a water collector 1 is provided inside the bottom of the culture medium 14 or at the bottom of the culture medium.
6 is provided, and this water collector 16 is connected via a conduit 18 to a water level detection tube 20 whose position can be adjusted to the same level as the bottom of the culture medium or to a lower level than the bottom of the culture medium, Electrodes 22 and 24 are provided to detect the lower limit level and upper limit level of the water level in the cylinder 20, respectively.
is connected to the controller 26 and set to output an irrigation start command and an irrigation stop command of the irrigation device respectively within the range where the moisture content in the culture medium is arbitrarily set, and furthermore, the excess water from the culture medium is supplied to the outside of the culture medium 14. A metering cylinder 32 capable of collecting and metering water and having drainage means is provided, and an electrode 36 for detecting the water level in the metering cylinder 32 is provided, and the electrode 36 detects the water level set in the metering cylinder 32 and controls the same. The controller 26 is set to output an irrigation stop command to the irrigation system, and the electrode 36 provided on the metering cylinder 32 and the water level detection tube 2
A changeover switch 38 for selectively using the electrode 24 for detecting the upper limit level set at 0 and the irrigation stop command detected by the controller 2
6.

In the above-mentioned automatic irrigation control device, the selection between the irrigation stop command from the metering cylinder 32 and the irrigation stop command from the water level detection tube 20 is sent from a regulator that can set an arbitrary number of irrigations or from a fertilizer concentration meter in the medium. It is preferable that the changeover switch 38 provided in the controller 26 be configured to be automatically switched and selected based on the signal.

Preferably, the controller 26 is provided with a timer 30 that can be set to delay the output of the irrigation stop command beyond the operating time between the start of irrigation and the stop of irrigation by the water level detection tube 20.

[Effect]

According to the automatic irrigation control device of the present invention, in a culture medium such as rock wool, the water supplied into the culture medium is divided into capillary water that is dispersed and moved by capillary action, and gravity water that is distributed at the bottom of the culture medium under the influence of gravity. Water can be retained in the form of water, and the moisture content at this time can be determined by connecting the water column inside the bottom of the medium and a water level detecting tube installed outside with a conduit. It has been confirmed that the difference in water level in the detection cylinder (hcm) has a correlation with the pF value (=log h) of the culture medium based on the measurement principle known as the so-called "sand column method" or "earth column method." Therefore, it is possible to properly adjust the moisture content of the culture medium by detecting the lower and upper limits of the water level of the water level detection tube corresponding to the moisture content of the culture medium, and outputting commands to start and stop irrigation to the irrigation device, respectively. can.

〔Example〕

Next, embodiments of the automatic irrigation control device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a hydroponic cultivation system using a culture medium showing the basic configuration of an automatic irrigation control device according to the present invention. In FIG. 1, reference numeral 10 indicates a pedestal, on which a water receiving member 12 made of a required container or isolation sheet is provided, and a culture medium 14 made of rock wool or the like is placed thereon. However, a water collector 16 is buried in the bottom of the culture medium 14, and a water level detection cylinder 20 is provided outside the culture medium 14 at a lower level than this. Then, the water collector 16 and the water level detection cylinder 20 are connected to the conduit 1.
8 to communicate with each other. In addition, the water level detection tube 20 has level detection electrodes 22 for detecting water levels that command the start and stop of irrigation, respectively.
(e ₂ ), 24 (e ₁ ) are provided, and these electrodes 22, 24
The controller 26 detects the energization state of the water level detecting cylinder 20 which also serves as an electrode (e ₃ ), and controls the watering device 28 as appropriate to properly water the culture medium 14.

Next, details of the automatic irrigation control device configured as described above will be explained along with its operation. First, medium 1
As for 4, rock wool is most suitable, but
Other sand, gravel, smoked charcoal, peat moss, perlite,
Conventionally known culture medium materials such as vermiculite can be used. A watering device 28 that supplies required water to the culture medium 14 is connected to the controller 2.
It is configured to operate in response to an irrigation start command signal from 6 to perform irrigation, and to stop irrigation in response to an irrigation stop command signal. However, the irrigation device 28
The water supplied to the medium 14 by irrigation from the medium 14 diffuses and permeates into the medium in the form of capillary water and gravity water. In this way, when the water content in the medium increases, the medium 14 is affected by gravity.
The moisture distribution in the lower part increases, and a moisture distribution unique to the culture medium 14 is formed in a state where the gravitational water subjected to the gravitational action and the capillary water diffused by capillary action are in equilibrium. At this time, the water distributed within the culture medium 14 is collected by a water collector 16 placed in the bottom of the culture medium 14 and stored in the water level detection tube 20 via the conduit 18. Therefore, for example, when the moisture content at the bottom of the culture medium 14 reaches 100%, the water level detection tube 20
The water level is approximately the same level as the bottom of the culture medium 14. Additionally, if the moisture content in the culture medium 14 decreases due to evapotranspiration, the moisture content in the bottom of the culture medium 14 will also gradually decrease, and the water level in the water level detection tube 20 will also decrease accordingly to maintain an equilibrium state. do. This relationship is based on the “PF-containing moisture (volume %) characteristics” of medium 14.
As mentioned above, it is defined based on , and has reproducibility.

In the above configuration, the water collector 16 may be constructed of a porous hollow body made of cotton-like woven fabric, ceramics, bisque-like material, etc. with good water permeability, and the conduit 18 may be connected to this porous hollow body. . In this case, it is preferable to apply a root cutting sheet to prevent roots from entering the pores. Also, water collector 1
6 can also be constructed by attaching a water collection pad made of cotton-like woven fabric or the like with low porosity to the open end of the conduit 18. Note that the water collectors 16 having the above-described configuration are all in communication with the conduit 18 even when the moisture content in the bottom of the culture medium is at its lowest. By selecting a member that has PF-containing water properties that do not suck air from inside the water collector 16 through the wall surface, water column connection is maintained between the inside of the culture medium bottom and the water level detection tube 20 via the conduit 18, An appropriate equilibrium relationship can always be maintained between the water content in the bottom of the culture medium and the water level in the water level detection cylinder 20.
Furthermore, as described above, in order for the water level detection tube 20 to detect a water level that is appropriately proportional to the moisture content in the bottom of the medium, the amount of water flowing between the culture medium 14 and the water level detection tube 20 must be minimized. is important, and in this case, the diameter of the water level detection tube 20 should be made as fine as possible (approximately 15 mm).
It was confirmed that it is effective if set to φ or less. Furthermore, in hydroponic cultivation using rock wool as a medium, the moisture content of the medium is set in an extremely high range (for example, the moisture content in the bottom of the medium is 70 to 97%). In such a case, it is sufficient to eliminate the water collector 16 as described above and to directly enclose the open end of the conduit 18 with a piece of rock wool.

As mentioned above, if the moisture content in the bottom of the culture medium and the water level in the water level detection tube 20 can be set to be appropriately proportional, the water level in the water level detection tube 20 will change depending on the setting range of the moisture content in the bottom of the culture medium. can be set. Therefore, the electrode 24 is positioned at the upper limit water level in the water level detecting tube 20 that corresponds to the maximum moisture content to be applied to the culture medium and at which a water stop command is issued. In addition, the level detection electrode 22 is positioned at the lower limit water level at which a preset evapotranspiration occurs and an irrigation start command is generated at the lower limit water level in the water level detection tube 20 when the water content in the culture medium decreases. In this way,
The water level in the water level detection tube 20 is detected by the electrodes 22 and 24, and when the water level falls below the set level of the electrode 22, the water irrigation device 28 is activated by the controller 26.
automatic irrigation capable of maintaining the moisture content of the culture medium 14 within a set range by outputting an irrigation start command to the water level, and similarly outputting an irrigation stop command when the water level reaches the set level of the electrode 24. Control can be easily achieved.

In addition, in the currently commercialized culture medium using Rotsukwool, etc., as fertilizers are repeatedly applied, the composition concentration of the fertilizer in the medium changes, and if it exceeds a certain limit, it may cause problems in crop growth. .
For this reason, it is necessary to apply extra fertilizing water to the culture medium and discharge the excess water equivalent to the outside of the culture medium in order to optimize the composition concentration of the fertilizer. In this case, the amount of surplus water is generally approximately 5 to 20% more than the amount of evapotranspiration in the culture medium each time irrigation is performed.
A method has been adopted in which it flows out of the culture medium. It is a fact that such discharge of surplus water results in wasted use of liquid fertilizer, etc., and depending on the management of the amount of fertilizer applied, it is possible to detect the concentration of fertilizer in the culture medium and calculate the concentration value without draining surplus water every time after irrigation. The optimal method is to drain excess water once when a predetermined value is reached or every time irrigation is performed an arbitrary number of times. However, in the device of this embodiment described above, the water level detection tube 20 can manage the fertilization and irrigation in an amount equal to the amount of evapotranspiration in the culture medium. Due to the current situation, it is difficult to use the surplus water needed to adjust the fertilizer components for fertilization.

Therefore, in the above configuration, the water level detection tube 20 is used to manage the application of fertilizer in an amount equal to the amount of evapotranspiration in the culture medium, and after the irrigation stop command is output from the electrode 24, the following means are used to control The system is configured to supply the necessary surplus water. That is, when the controller 26 detects that the water level has reached the electrode 24 provided in the water level detection tube 20 and outputs a command to stop irrigation to the irrigation device 28, the irrigation is stopped from the time when the irrigation device 28 starts irrigation. The time required up to this point is measured, this measured time is converted into the amount of evapotranspiration, the necessary amount of surplus water is determined, and the output signal of the irrigation stop command is delayed. For this reason, a timer (delay timer) 30 is built into the controller 26, and for example,
If 10% surplus water is required, set the timer 30 to the time required from the start of irrigation to the stop of irrigation.
By setting the time multiplied by 0.1, the irrigation stop command can be delayed by the time set by the timer 30, and the above-mentioned surplus water can be supplied during this time. At this time, a hole is provided in the lower part of the water receiving member 12 so that excess water can be drained. As mentioned above, surplus water is used for the purpose of optimizing the fertilizer components in the culture medium, so depending on the introduction of absolute amount control of the amount of fertilizer applied or depending on the culture medium, it may be necessary to use this water every time when applying fertilizer. Even if it is not carried out, it may be sufficient to carry out the treatment, for example, once or twice a day or every time you perform irrigation. Therefore, in such a case, the controller 26 may be equipped with an adjustment function that allows the timing of the timer 30 to be arbitrarily set every one to several times of irrigation in conjunction with a 24-hour timer, irrigation frequency meter, etc. By using the device and setting reservations, it is possible to eliminate waste of fertilizer and irrigation water and achieve economical automatic irrigation control.

FIG. 2 is a configuration diagram of a hydroponic cultivation system showing a typical embodiment of the automatic irrigation control device according to the present invention. That is, in the embodiment shown in FIG. 2, the culture medium 14 provided with the water collector 16 and the water level detection cylinder 20 as shown in FIG. The system includes a measuring cylinder 32 that collects and measures excess water. Therefore, in FIG. 2, the same components as those shown in FIG. 1 are given the same reference numerals, and detailed explanations will be omitted. In FIG. 2, the measuring cylinder 32 is attached to a part of the pedestal 10 on which the water receiving member 12 is placed. In this case, the metering cylinder 32
is located outside the water receiving member 12, that is, outside the culture medium 14, and is separated from the inside of the culture medium 14 by a water passage 34 as appropriate.
is configured to collect excess water from the culture medium 14 via the medium 14 . Further, the metering cylinder 32 is provided with a level detection electrode 36 (e ₁ ) for detecting the water level at which a command to stop irrigation is provided, and the controller 26 detects the energization state of the electrode 36 to control the irrigation device 28 as appropriate ( (output of irrigation stop command). In this case, the controller 26 is provided with a changeover switch 38 to switch the water level detection signal from the electrode 36 provided on the measuring cylinder 32 and the water level detection signal from the electrode 24 provided on the water level detection cylinder 20 for detecting the upper limit level. The configuration is configured to allow selective input.
Further, a drain pipe 40 is led out from the bottom of the measuring cylinder 32, and an automatic opening/closing valve 42 is provided in the drain pipe 40. However, the automatic on-off valve 4
The valve 2 is closed during irrigation, and is set to open as appropriate when irrigation is stopped by a signal based on the stop command or a signal based on a change in water pressure in the irrigation supply line.

Next, the operation of the automatic irrigation control device according to this embodiment configured as described above will be explained. First, when the changeover switch 38 is connected to the electrode 24 of the water level detection tube 20 in the controller 26, the water level detection tube 20 performs evapotranspiration equivalent irrigation control. In addition, when the changeover switch 38 is connected to the electrode 36 of the measuring cylinder 32, surplus water from the culture medium 14 is collected through the water passage 34 communicating with the measuring cylinder 32, and when this surplus water reaches a predetermined amount. Irrigation is stopped by issuing an irrigation stop command. Measuring cylinder 3
The surplus water collected in 2 can be drained manually or automatically as appropriate. This makes it possible to appropriately control the fertilizer components in the medium as described above.
In this case, the switching control from the electrode 24 side to the electrode 36 side of the changeover switch 38 is performed using a 24-hour timer that can reserve and set the switching time to generate the switching signal described above, and a 24-hour timer that counts the number of times of irrigation. Automatically using a regulator that can be set arbitrarily to generate a switching signal every time, or a measuring device that measures the concentration of fertilizer components in the culture medium and generates a switching signal when the measured value reaches a predetermined value. It can be done in a specific manner.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention, changes in moisture content in a culture medium such as rock wool due to evaporation and irrigation are detected as changes in the moisture distribution within the culture medium, and this is detected by a water level detection tube provided externally. By configuring the system to detect the change in water level, it is possible to realize appropriate and low-cost fertilization and irrigation control with a relatively simple structure.
Adjustment of water content in the medium can be achieved quickly and with high precision.

In particular, according to the present invention, by providing a measuring cylinder outside the culture medium to collect surplus water from the culture medium, it is possible to appropriately adjust the water content in the culture medium according to the amount of this surplus water.

Therefore, according to the present invention, in order to optimize the fertilizer components when fertilization and irrigation are repeated many times,
In addition to the irrigation amount relative to evapotranspiration,
Irrigation of surplus water equivalent to ~20% can be achieved simply and in a timely manner by using the controller's timer, the number of irrigations, the fertilizer concentration in the culture medium, etc.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a hydroponic culture system using a medium showing the basic structure of an automatic irrigation control device according to the present invention, and Fig. 2 is a hydroponic cultivation system using a medium showing an embodiment of the automatic irrigation control device according to the present invention. FIG. 1 is a configuration diagram of a system. DESCRIPTION OF SYMBOLS 10... Frame, 12... Water receiving member, 14... Culture medium, 1
6... Water collector, 18... Conduit, 20... Water level detection tube, 2
2, 24... Electrode, 26... Controller, 28... Irrigation device, 30... Timer, 32... Measuring cylinder, 3
4... Water passage, 36... Electrode, 38... Changeover switch,
40...Drain pipe, 42...Automatic opening/closing valve.

Claims (1)

[Scope of Claims] 1. A hydroponic cultivation system that uses a culture medium configured to measure the moisture content of the culture medium and control the irrigation device to maintain the moisture content of the culture medium within a set range, and that communicates with the culture medium. In an automatic irrigation control device, the automatic irrigation control device is provided with a water level detection cylinder, an electrode is provided for detecting the water level in the water level detection cylinder, and the controller is controlled by the electrode to control the start and stop of irrigation of the irrigation device. , a water collector 1 inside the bottom of the culture medium 14 or at the bottom of the culture medium
6 is provided, and this water collector 16 is connected via a conduit 18 to a water level detection tube 20 whose position can be adjusted to the same level as the bottom of the culture medium or to a lower level than the bottom of the culture medium, Electrodes 22 and 24 are provided to detect the lower limit level and upper limit level of the water level in the cylinder 20, respectively.
is connected to the controller 26 and set to output an irrigation start command and an irrigation stop command of the irrigation device respectively within the range where the moisture content in the culture medium is arbitrarily set, and furthermore, the excess water from the culture medium is supplied to the outside of the culture medium 14. A metering cylinder 32 capable of collecting and metering water and having drainage means is provided, and an electrode 36 for detecting the water level in the metering cylinder 32 is provided, and the electrode 36 detects the water level set in the metering cylinder 32 and controls the same. The controller 26 is set to output an irrigation stop command to the irrigation system, and the electrode 36 provided on the metering cylinder 32 and the water level detection tube 2
A changeover switch 38 for selectively using the electrode 24 for detecting the upper limit level set at 0 and the irrigation stop command detected by the controller 2
An automatic irrigation control device characterized by being provided at 6. 2. Selection between the water stop command from the metering cylinder 32 and the water level detection cylinder 20 can be made using a signal sent from a regulator that can set the number of irrigations or a fertilizer concentration meter in the medium provided in the controller 26. 2. The automatic irrigation control device according to claim 1, wherein the changeover switch 38 is configured to automatically select the changeover. 3 The controller 26 exceeds the operating time from the start of irrigation to the stop of irrigation by the water level detection tube 20,
2. The automatic irrigation control device according to claim 1, further comprising a timer 30 which can be set to delay the output of the irrigation stop command.