JPH0463655B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for applying liquid fertilizer water to plants grown in artificial soil using liquid fertilizer in an amount commensurate with the amount of transpiration. The present invention relates to a liquid fertilizer irrigation control device for hydroponic cultivation that continues irrigation until the amount is discharged.

<Conventional technology> When performing hydroponic cultivation in an artificial medium such as Rotsukwool pine, the amount of culture solution absorbed by each plant is measured, and a culture solution commensurate with that amount is supplied to each plant. Although it would be ideal if it were possible to do so, in reality it is difficult to implement for technical and economic reasons. Therefore, it is customary to measure the amount of transpiration at a specific location under the same growth conditions to represent a large bed area where many plants are grown, and to manage overall irrigation based on the measurement results.

An example of a device in this case is that a recess is formed in the lower central part of the rock wool bed to serve as a reservoir for excess culture solution, and two electrodes for water level detection are attached to the recess to allow the cultivation of crops. As the liquid evaporates, the liquid in the liquid pool is sucked up in the capillary tube of the bed, and when the lower electrode detects that the level has dropped to a predetermined level, an irrigation start signal is issued, and irrigation begins, and the liquid pool is drawn up again. When excess culture solution accumulates in the tank, an electrode at a high position senses that the water has reached a predetermined level and issues a signal to stop irrigation.

The above-mentioned recesses may cause problems such as not necessarily being representative of the whole depending on how well they are formed, so a stainless steel tray with a liquid pool formed therein is installed horizontally, and a capillary mat is placed on the inner surface of the tray. It is also known that a bed made of rock wool is formed on the bed. The capillary mat is used to make it possible to suck up excess culture solution accumulated in the liquid pool of the metal tray into the bed.

Furthermore, the present applicant has set up an irrigation stop signal in order to prevent waste products from the roots from accumulating in the medium and to wash them out each time with irrigation, and to continue the irrigation filtration until a predetermined amount of liquid has been discharged. A separate application has been filed for a device that uses a timer in place of the emitting electrode, which allows the duration of irrigation to be set arbitrarily.

<Problems to be Solved by the Invention> As mentioned above, using a timer to control the amount of liquid to be discharged based on the irrigation duration increases equipment costs compared to electrodes, and also causes problems such as power outages. In addition to the above-mentioned timer, this is a safety device that once returns the water level in the liquid pool to normal when the original control operation resumes after the accident has been resolved and the control operation continues to be uncontrollable. This requires sub-timers, control circuits, etc., and tends to make the device complex and sophisticated.

<Means for Solving the Problems> In order to eliminate such drawbacks, this invention cultivates plants hydroponically in an artificial medium laid on the inner surface, so that excess water is collected in a pool formed in the longitudinal direction. An electrode and a receiver are installed in series to receive the overflow liquid from the overflow pipe attached to the side of the liquid pool, and an electrode and a receiver are installed to issue an irrigation start signal when contact with the liquid in the liquid pool is cut off. By providing a means for arbitrarily setting the amount of accumulated liquid in the tank and allowing it to be discharged all at once when the amount of accumulated liquid is reached, and an electrode that comes into contact with the drained liquid from the receiving tank and issues an irrigation stop signal, Irrigation control based on liquid volume can be performed easily and inexpensively, and irrigation can be performed in small amounts and many times, which is desirable for plant growth.

<Example> The present invention will be described below using an example shown in the drawings.

In FIG. 1, reference numeral 1 denotes a tray made of stainless steel, and a liquid reservoir 2 having a V-shaped cross section is formed in the center portion of the bottom surface over the entire length in the longitudinal direction. A capillary mat 3 is laid on the inner surface of the tray 1, including the liquid reservoir 2, and a rock wool mat serving as an artificial medium 4 is placed on top of the capillary mat 3, and plants 5 are grown in accordance with a conventional method.
hydroponic. Although not shown in the drawings, if necessary, a root cutting sheet is placed on top of the capillary mat 3. A liquid reservoir 2 in which excess irrigation water accumulates passes through one side plate of the tray 1 to form an outwardly projecting portion 6 and terminates in an end plate 7 provided with an overflow pipe 8. The upper limit of the water level of the liquid reservoir 2 is determined by the installation position of the overflow pipe 8. The upper part of the outwardly protruding part 6 is opened, and an electrode 9 for water level measurement, which is shown in FIG. 2 and has a threaded structure and can be raised and lowered, is mounted thereon. The electrode 9 works in cooperation with the ground electrode 15 to amplify the electrical change that occurs when the tip of the electrode 9 leaves the liquid surface using an amplifier circuit, and uses this as an irrigation start signal. The structure is such that the terminal plate 9a does not loosen even when the electrodes are moved up and down. Overflow liquid from the overflow pipe 8 is collected in a receiving tank 10. One feature of the present invention is that the receiving tank 10 is equipped with a means 11 that allows the amount of liquid stored in the tank to be arbitrarily set and allows the liquid to be discharged all at once when the amount of stored liquid is reached. As a specific example of such means 11, the first
In the illustrated example, a siphon tube 11a is used in which the height of the siphon can be changed. Receiving tank 10
In this example, the liquid discharged all at once receives a discharge tank 12, and its discharge from the discharge tank 12 is restricted by a small-diameter discharge pipe 13 provided in this discharge tank 12. Therefore, the discharge tank 12, which was initially empty,
At the initial stage of receiving the liquid discharged from the receiving tank 10 at once, the water level temporarily rises rapidly, then the water level gradually decreases, and eventually becomes empty again. Using this discharge tank 12, an electrode 14 having the same structure as the electrode 9 is attached.

Next, we will move on to an explanation of the operation when the above configuration is adopted. It is now assumed that the liquid reservoir 2 is filled with excess culture liquid at a level determined by the overflow pipe 8. Since the liquid in the liquid pool 2 is sucked up as the plants 5 transpire, a time will come when the liquid level will separate from the tip of the electrode 9. The electrical signal at this time is amplified and sent to a control circuit to start irrigation. In this way, although not shown in the drawings, the culture solution is supplied all at once from the irrigation tubes provided for each cultivation location of each plant 5. As the supply continues, overflow from the overflow pipe 8 begins, and the overflow liquid accumulates in the receiving tank 10, gradually raising the water level. When the water level exceeds the height of the siphon, the liquid is discharged all at once from the siphon pipe 11a to the discharge tank 12. Since the discharge pipe 13 of the discharge tank 12 that receives this has a small diameter as described above,
The liquid accumulates in the discharge tank 12 without being drained. Therefore, if the electrode 14 is deeply inserted to near the bottom of the discharge tank 12, the liquid surface will come into contact with the electrode 14 almost at the same time as discharge is performed by the movement of the siphon tube 11a. The electrical signal obtained at this time is amplified and sent to a control circuit to stop irrigation. In this way, irrigation control based on liquid volume is achieved.

In the above-mentioned siphon tube 11a, the water level can be set to A by stretching it high as shown by the dashed line in FIG.
Alternatively, the amount to be discharged all at once can be set arbitrarily by lowering the water level to B as shown by the solid line, but such means 11 is not limited to the siphon tube 11a, and is based on the principle of shishiodoshi shown in FIG. It may be based on That is, if the receiving tank 10 is rotatably provided on one side of the pivot point 11b, the weight 11c is provided on the opposite side so that it can be set at any desired position. Even in this case, if the equilibrium state with the weight 11c is disrupted due to the liquid accumulated in the receiving tank 10, the liquid will fall and be discharged all at once, and after discharge, the weight 11c will return to the original state. Further, the amount of liquid discharged can be increased or decreased depending on the set position of the weight 11c.

Furthermore, although the discharge tank 12 is provided in the embodiment described above, the installation of the discharge tank 12 is not essential, and may be omitted as long as the discharge from the receiving tank 10 can be reliably detected with the electrode 14. .

<Effects of the Invention> According to the above configuration, even if all the liquid in the liquid reservoir 2 is consumed as a result of an uncontrollable state due to an accident during a power outage, as soon as the accident is corrected, the air and Irrigation is started by the action of the electrode 9 that is touching, the surplus irrigation amount is accumulated up to the upper limit water level determined by the installation position of the overflow pipe 8, and the irrigation is finished when the predetermined amount of overflow liquid is released. state, and there is no need to get help from a conventional sub-timer.

Moreover, since the means 11 is provided which allows the amount of accumulated liquid in the receiving tank 10 to be arbitrarily set and which allows the liquid to be discharged all at once when the amount of accumulated liquid is reached, the amount to be discharged outside the system each time irrigation can be changed as desired. By applying excess water, waste products from the roots can be washed away, and together with the action of the electrode 12, preparations for the next cycle can be quickly completed. Therefore, by setting the electrode 9 to be slightly lower than the upper limit water level determined by the set position of the overflow pipe 8, it is possible to prevent changes in moisture and concentration within the culture medium 4, and thus stress in the rhizosphere area. Irrigation of small amounts and multiple times can be achieved with a simple and inexpensive device.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of the liquid fertilizer irrigation control device for hydroponic cultivation according to the present invention, FIG. 2 is a sectional view showing the structure of the electrode, and FIG. 3 is a sectional view of the siphon tube shown in FIG. 1. FIG. 4 is a diagram showing another example in place of the siphon tube. 1...Tray, 2...Liquid pool, 3...Capillary pine, 4...Artificial medium, 5...Plant, 8...
... Overflow pipe, 9, 14 ... Electrode, 10 ... Receiving tank, 1
1...Means for making it possible to arbitrarily set the amount of accumulated liquid in the receiving tank and to discharge it all at once when the amount of accumulated liquid is reached.

Claims (1)

[Scope of Claims] 1. Plants 5 are cultivated hydroponically in an artificial medium 4 laid on the inner surface, and excess water is collected in a liquid pool 2 formed in the longitudinal direction.
When a tray 1 that collects liquid in the liquid pool 2 and a receiving tank 10 that receives the overflow liquid from the overflow pipe 8 attached to the side of the liquid pool 2 are installed in series, and the contact with the liquid in the liquid pool 2 is cut off. Electrode 9 that emits an irrigation start signal, receiver tank 1
means 11 that can arbitrarily set the amount of accumulated liquid in 0 and discharge the liquid all at once when the amount of accumulated liquid is reached; and an electrode 14 that comes into contact with the drained liquid from the receiving tank 10 and issues an irrigation stop signal. A liquid fertilizer irrigation control device for hydroponic cultivation. 2. The means 11 which can arbitrarily set the amount of accumulated liquid in the receiving tank 10 and discharge it all at once when the amount of accumulated liquid is reached is a siphon pipe 11a that is attached to the bottom of the receiving tank 10 and whose height is variable. A liquid fertilizer irrigation control device for hydroponic cultivation according to claim 1.