Drainage management device, irrigation management system, and drainage management method for hydroponic cultivation

Abstract

The purpose of the present invention is to easily manage drainage in hydroponics.　A drainage temperature sensor 12 capable of measuring the temperature of drainage is provided in a discharge path of the drainage, and when the drainage temperature sensor 12 detects a temperature change of a prescribed amount or more, the sensor indicates that the drainage has reached the discharge path. If the temperature change can be measured by the drainage temperature sensor 12, the presence or absence of drainage can be determined, making it easy to know when drainage has occurred throughout the day. A drainage temperature sensor capable of being brought into contact with the drainage is only required to be installed in the discharge path, the structure is extremely simple, and the attaching work is extremely easy.

Description

Technical Field

[0001] The present invention relates to a technique for managing drainage and irrigation in hydroponic culture. Background Art

[0002] As an irrigation apparatus for supplying a culture solution in hydroponic culture, for example, the one disclosed in Patent Document 1 is known. This apparatus stores optimal irrigation time and optimal irrigation intervals for each type of plant, and can automatically perform appropriate irrigation suited to the target plant to be cultivated when the type of the plant to be cultivated is selected. In addition to the type of plant, the apparatus is also provided with a correction means for further optimizing the irrigation interval. As the correction means, it performs detection of soil compaction degree, detection of soil specific gravity, detection of soil particle size, detection of soil water retention degree using the amount of water detected by a water quantity sensor disposed at a drainage outlet, detection of water permeation time from water supply until moisture is detected by a water sensor disposed directly under the drain hole of a flower pot, detection of ambient temperature around the plant by a temperature sensor installed around the plant, detection of ambient humidity around the plant by a humidity sensor installed around the plant, detection of air volume around the plant, and detection of solar radiation around the plant, and it is described that the irrigation interval is corrected using various data obtained from the above detections.

[0003] Patent Document 2 discloses a technique that detects the temperature of a water supply path and the ground temperature, and controls the irrigation amount based on the relationship between the temperature of the water supply path and the ground temperature.

[0004] Patent Document 3 discloses an apparatus in which the same number of irrigation tubes branched from a liquid supply pipe are used to irrigate each of hydroponic culture media placed on a cultivation bench, a medium weight measuring device is installed between part of the hydroponic culture media and the cultivation bench, the medium weight is measured together with time information, thereby the change in the cumulative liquid supply amount depending on irrigation conditions is graphed in time series for monitoring.

[0005] Non-patent document 1 discloses a device that stores wastewater in a wastewater tank, stops the supply of liquid when the amount of wastewater exceeds a predetermined level, drains the wastewater from the wastewater tank until it returns to a predetermined level, and then resumes supplying liquid as set, repeating this process. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-70653 [Patent Document 2] Japanese Patent Publication No. 2024-135 [Patent Document 3] Japanese Patent Publication No. 2018-14902 [Non-patent literature]

[0007] [Non-Patent Document 1] Toyotane Co., Ltd., Homepage, Product Information, Description of the Water Supply and Drainage Measurement Device "Haieki Toban" (Product Name) URL: https: / / www.toyotane.co.jp / products / 001903.html [Non-Patent Document 2] Inochio Holdings Co., Ltd., Homepage, Product corresponding to Patent Document 3: Description of Slab sight (registered trademark) URL: https: / / inochio.co.jp / products / cultivation-systems / slabsight [Non-Patent Document 3] Priva's manual for Priva Groscale: URL: https: / / www.manualslib.com / manual / 1742601 / Priva-Compass.html?page=103#manual [Overview of the project] [Problems that the invention aims to solve]

[0008] The technologies disclosed in Patent Documents 1 and 2 use various sensors to understand soil conditions, as well as the temperature and humidity around plants, the temperature of the water supply path, and the soil temperature, in order to optimize the amount and interval of irrigation. However, it is necessary to know various conditions from irrigation to drainage, which requires the use of specialized equipment. Furthermore, when managing multiple greenhouses, introducing many such devices is extremely costly.

[0009] On the other hand, the apparatus disclosed in Non-Patent Document 1 utilizes a method to simplify irrigation management by measuring the amount of irrigation solution supplied and the amount of drained solution, and determining the daily drainage rate based on the ratio of the two. When the drainage rate shows a favorable value, it means that the moisture content in the growing medium is appropriate and irrigation management is being carried out well. This favorable drainage rate varies depending on the type of plant, the type of growing medium, and the season, but is generally considered to be in the range of 8-40%, for example, around 30% is considered favorable for tomatoes. This method can be introduced at a relatively low cost because it only requires measuring the amount of irrigation solution supplied and the amount of drained solution.

[0010] However, drainage may be low during the day and high in the morning and evening. This is because there is sufficient sunlight during the day, and the plants have a high water requirement. On the other hand, it is necessary to supply sufficient air to the growing medium at night, so irrigation in the evening should be avoided. However, in the case of the apparatus described in Non-Patent Document 1, the drainage rate is calculated only once a day. Therefore, even if the daily drainage rate is a target value, for example, around 30%, it is possible that the control is not appropriate to the changes in the plants' water requirement over time throughout the day.

[0011] In contrast, Patent Document 3 describes a method for measuring the weight of a growing medium by installing a growing medium weight measuring device and measuring the weight of the growing medium along with time information, thus enabling time-series management of the irrigation status over a day. However, in order to know the irrigation status with higher accuracy, the growing medium weight measuring device of Patent Document 3 is installed on a cultivation bench that supports multiple hydroponic growing media, and captures the weight changes of multiple hydroponic growing media. Therefore, as shown in Non-Patent Document 2, which describes a product corresponding to Patent Document 3, the growing medium weight measuring device must be large enough to measure a growing bench that supports multiple hydroponic growing media, and must be installed to firmly support the cultivation bench and not be easily removed. Consequently, the growing medium weight measuring devices of Patent Document 3 and Non-Patent Document 2 are complicated to install, and if they need to be moved after being installed, the removal and reinstallation work becomes even more complicated, increasing the labor costs. The device disclosed in Non-Patent Document 3 also measures the weight of the growing medium in the same way as the device disclosed in Non-Patent Document 2, but the installation work is large-scale and has the same problems as Non-Patent Document 2.

[0012] The present invention has been made in view of the above, and aims to provide a technology that does not require extensive installation work, is easy to attach and detach, is compact, can easily accommodate the relocation of culture media, and can reliably manage drainage. [Means for solving the problem]

[0013] To solve the above problems, the present invention provides: A drainage temperature sensor is installed in the drainage path of the drainage liquid discharged from the growing medium in which the plants to be cultivated are planted, and is capable of measuring the temperature of the drainage liquid. A drainage determination unit receives measurement data from the drainage temperature sensor and determines the timing at which a temperature change exceeding a predetermined level is detected as the drainage timing at which the drainage occurred. Drainage management device for hydroponic cultivation To provide.

[0014] It is preferable to comprise a medium support frame that supports the medium, wherein the discharge path is provided on the medium support frame, a retention part for temporarily retaining the discharged liquid is provided in the discharge path, and a temperature sensing part of the drainage temperature sensor is provided so as to be capable of contacting the discharged liquid in the retention part. It is also preferable that the discharge path is configured to include a drainage pipe, the drainage temperature sensor is provided such that the temperature sensing part is positioned inside the drainage pipe, and a guide member that guides the discharged liquid to contact the temperature sensing part is provided in the drainage pipe on an upstream side of a position where the temperature sensing part is provided. Furthermore, it is preferable that a heating member for heating the drainage temperature sensor is provided.

[0015] Further, in the present invention, the above-described drainage management device, a liquid supply part that supplies a culture solution to a plant to be cultivated, a liquid supply temperature sensor capable of measuring a supply temperature of the culture solution, a liquid supply determination unit that receives measurement data from the liquid supply temperature sensor and determines a timing at which a temperature change of a predetermined magnitude or more is detected as a liquid supply timing at which the liquid supply is performed, and an irrigation management system for nutrient solution cultivation comprising is provided. It is preferable that a heating member for heating the liquid supply temperature sensor is provided. It is also preferable that the liquid supply temperature sensor is configured such that a temperature sensing part is provided near a discharge port of the liquid supply part, and measures a temperature of the culture solution discharged from the discharge port as the liquid supply temperature. It is also preferable that the liquid supply temperature sensor is configured such that a temperature sensing part is positioned inside a liquid supply pipe constituting the liquid supply part, and measures a temperature of the culture solution passing through the liquid supply pipe as the liquid supply temperature.

[0016] Further, in the present invention, when a drainage temperature sensor, which is provided in a discharge path of drainage discharged from a medium where a plant to be cultivated is planted so as to be capable of measuring a temperature of the drainage, exhibits a temperature change of a predetermined magnitude or more, the presence or absence of drainage is managed with this timing as the drainage timing at which the drainage is generated Drainage management method for nutrient solution cultivation is provided. In this case, it is preferable to pre-heat the drainage temperature sensor and measure the temperature of the drainage. Effects of the Invention

[0017] According to the present invention, a drainage temperature sensor provided to be capable of measuring the temperature of drainage is disposed in a drainage discharge path, and when the drainage temperature sensor detects a temperature change equal to or greater than a predetermined value, it indicates that drainage has reached the discharge path. That is, it indicates that the culture solution has spread throughout the culture medium, and the water retention amount in the culture medium has reached a full state. If a temperature change can be measured by the drainage temperature sensor, the presence or absence of drainage can be determined, so the timing at which drainage occurs in one day can be easily known. In the present invention, it is only necessary to provide a drainage temperature sensor that can contact drainage in the discharge path, so the structure is extremely simple and the installation work is also extremely easy. Installation work only requires fixing the sensor at a predetermined position on the discharge path, so removal is also easy, and it can easily cope with the relocation of the culture medium. Brief Description of the Drawings

[0018] [Figure 1] Fig. 1(a) is a diagram showing a schematic configuration of a drainage management device according to one embodiment of the present invention, and Fig. 1(b) is an enlarged view of a portion where the drainage temperature sensor is disposed. [Figure 2] Fig. 2 is a diagram for explaining the flow direction of drainage. [Figure 3] Fig. 3(a) is a diagram showing a schematic configuration of an irrigation management system including the above drainage management device, and Fig. 3(b) is an enlarged view of a portion where a liquid supply temperature sensor is disposed. [Figure 4] Fig. 4 is a diagram showing the above irrigation management system and a culture medium supported by a culture medium support frame. [Figure 5] Fig. 5 is a diagram showing the overall configuration of the above irrigation management system in a state where the culture medium is set on the culture medium support frame. [Figure 6] Fig. 6 is a diagram showing the measurement results of Experimental Example 1. [Figure 7] Figure 7 shows the measurement results for Experimental Example 2. [Figure 8] Figure 8 shows an example of the measurement results from Experimental Example 3. [Figure 9] Figure 9 shows another example of the measurement results from Experimental Example 3. [Figure 10] Figure 10 is a diagram showing a schematic configuration of an irrigation management system according to another embodiment of the present invention. [Figure 11] Figure 11(a) is an enlarged view of the area where the liquid supply temperature sensor is located, Figure 11(b) is a perspective view showing the configuration of the drainage regulating member, and Figure 11(c) is a diagram illustrating the placement of the drainage regulating member and the drainage temperature sensor. [Figure 12] Figure 12 is a side view of the irrigation management system shown in Figure 10. [Figure 13] Figure 13 shows the measurement results of Experiment Example 4, in which both the liquid supply temperature sensor and the drainage temperature sensor were not heated. [Figure 14] Figure 14 shows the measurement results of Experiment Example 4, in which both the liquid supply temperature sensor and the drainage temperature sensor were heated. [Figure 15] Figure 15 is a side view diagram illustrating yet another embodiment of an irrigation management system according to another embodiment of the present invention. [Figure 16] Figure 16 illustrates an embodiment in which a liquid supply passage is formed in a sensor support frame for arranging a liquid supply temperature sensor. [Figure 17] Figure 17 is a perspective view illustrating an irrigation management system according to yet another embodiment of the present invention. [Figure 18] Figure 18 is a perspective view illustrating the fluid supply unit used in the embodiment shown in Figure 17. [Figure 19]Figure 19(a) is a perspective view showing the drainage regulating member used in the embodiment of Figure 17; Figure 19(b) is a cross-sectional view of the drainage regulating member with a drainage temperature sensor attached to it; and Figure 19(c) is an external perspective view showing the drainage regulating member and drainage temperature sensor attached to the drainage pipe. [Modes for carrying out the invention]

[0019] The present invention will be described in more detail below based on embodiments shown in the drawings. Figure 1 is a schematic diagram showing the configuration of a drainage management device 1 according to one embodiment of the present invention. The drainage management device 1 includes a culture medium support frame 11, a drainage temperature sensor 12, and a drainage determination unit 13.

[0020] The culture medium support frame 11 is formed in the shape of a roughly rectangular box having a predetermined width and length, and has a bottom portion 11a and side portions 11b, 11b along the longitudinal direction. A synthetic resin plate 11c is placed on the bottom portion 11a, and the culture medium 2 is placed on this plate 11c (see Figures 4 and 5). The plate 11c has the function of suppressing the temperature rise of the culture medium 2. The culture medium 2 is composed of, for example, a planting medium 2a and a seedling medium 2b. In this case, the plants to be cultivated are raised as seedlings in the seedling medium 2b and then placed directly on the planting medium 2a for growth. The culture medium 2 is composed of rock wool, peat moss, coconut husks, etc. It should be noted that the form and materials of the culture medium 2 are not limited to these.

[0021] The culture medium support frame 11 is positioned with a slight incline to one side along its longitudinal direction, and as shown in Figure 2, the drainage is designed to flow to the lower side. A retention section 11d is provided at the longitudinal end located on the lower side where the drainage temporarily accumulates. A drainage hole 11e is also provided in the retention section 11d (see Figure 2), and a partition plate 11f is positioned diagonally so that the drainage flows toward this retention section 11d and the drainage hole 11e. The drainage of the culture medium discharged from the culture medium 2 flows toward the lower side in the longitudinal direction on the flat plate 11c surrounded by the side sections 11b, 11b, and is restricted by the partition plate 11f before flowing toward the retention section 11d and the drainage hole 11e. Therefore, the inside of the culture medium support frame 11, surrounded by the bottom section 11a, side sections 11b, 11b, etc., becomes the drainage path for the drainage.

[0022] The drainage temperature sensor 12 uses a glass thermometer, a metal thermometer, a thermocouple, a thermistor, etc., and is installed via a sensor support frame 12c at any point in the drainage path described above, preferably with the temperature sensing element 12a located in the stagnant section 11d. At the start of the day, before new drainage passes through the drainage path, the temperature sensing element 12a is not in contact with the new drainage, so a temperature approximately the same as the room temperature (house temperature) inside the greenhouse where the drainage management device 1 is installed is detected. On the other hand, when the supply of liquor is started and new drainage comes into contact with the temperature sensing element 12a, the detected temperature changes. The temperature change associated with contact with the drainage usually appears as a decrease in the detected temperature because the drainage temperature is lower than the house temperature, but depending on the season, the drainage temperature may be higher than the house temperature, and this may appear as an increase in detection sensitivity.

[0023] The drainage determination unit 13 receives measurement data from the drainage temperature sensor 12 and determines the timing at which a temperature drop or rise (temperature change exceeding a predetermined level) is detected as the timing at which drainage has occurred. The drainage determination unit 13 consists of a control panel including an electrical circuit that can receive measurement data and output the timing at which drainage has occurred, or it consists of a computer (personal computer, portable information terminal, etc.) with a computer program installed that receives measurement data from the drainage temperature sensor 12, compares it with previously received data to determine whether a temperature change exceeding a predetermined level has occurred, and outputs the timing at which drainage has occurred if a temperature change exceeding a predetermined level has occurred.

[0024] According to this embodiment, after the culture medium is supplied and spreads throughout the culture medium 2, when the culture medium is discharged from the culture medium 2 as drainage, the drainage flows through the discharge path of the culture medium support frame 11. When the drainage reaches the retention section 11d and comes into contact with the temperature sensing section 12a of the drainage temperature sensor 12, the temperature indicated by the drainage temperature sensor 12, which is sent to the drainage determination unit 13, becomes lower or higher than the temperature close to the ambient temperature inside the greenhouse at that time. If the drainage determination unit 13 determines that the decreased or increased temperature is above a predetermined threshold, it outputs that drainage has occurred. According to this embodiment, whether or not drainage has occurred can be detected solely by the change in temperature. Therefore, the timing of drainage during the day can be determined with an extremely inexpensive device.

[0025] Furthermore, since the occurrence of drainage can be detected by capturing temperature changes, even without a device configuration like the drainage management device 1 of this embodiment, the timing of drainage can be determined by placing the temperature sensing element 12a of the drainage temperature sensor 12 in the discharge path such as the retention section 11d, and having an operator visually check the temperature change. If it is confirmed that drainage has occurred, it means that the irrigation has been sufficiently carried out to reach the culture medium 2, thus preventing irrigation shortages even during the daytime when the plants have high water requirements. If the drainage temperature sensor 12 detects a temperature change above a predetermined level at a time when irrigation is not required, it means that unnecessary irrigation has been performed, and in that case, the irrigation operation should be stopped immediately. As a result, appropriate irrigation management, including irrigation operations, can be performed simply by managing the temperature of the drainage.

[0026] In this embodiment, drainage is determined when a temperature change exceeding a predetermined level is detected by the drainage temperature sensor 12. If the temperature of the drainage is not significantly different from the ambient temperature inside the greenhouse, which was detected by the drainage temperature sensor 12 before contact with the drainage, it becomes difficult to detect a temperature change exceeding the predetermined level. Therefore, it is preferable to preheat the drainage temperature sensor 12 to a predetermined level or higher. More preferably, it is heated to a temperature equal to or higher than the highest of the drainage temperature, supply liquid temperature, and ambient temperature inside the greenhouse. As a result, when the drainage comes into contact with the temperature sensing part 12a of the drainage temperature sensor 12, a significant temperature drop will occur, allowing for accurate detection of the timing of drainage even under conditions of high ambient temperatures inside the greenhouse during the day.

[0027] To heat the drainage temperature sensor 12 to a predetermined level, it is preferable to provide a heating member 14 connected to a heating power supply adjacent to the temperature sensing part 12a of the drainage temperature sensor 12, as shown in Figures 1(a) and (b). The heating member 14 can be any device capable of raising the temperature of the drainage temperature sensor 12; for example, a heater utilizing resistance heating can be used. It is preferable to pre-assemble the heating member 14 using a sensor support frame 12c so that it is positioned at a certain distance from the temperature sensing part 12a of the drainage temperature sensor 12, and to configure it so that the temperature, which decreases due to contact with the drainage, is quickly raised to a predetermined temperature.

[0028] As shown in Figures 3 to 5, the drainage management device 1 is combined with a liquid supply unit 21, a liquid supply temperature sensor 22, and a liquid supply determination unit 23 to constitute the irrigation management system 100. The liquid supply unit 21 can be any device that supplies liquid to the culture medium in which the plants to be cultivated are planted, and is configured to have a liquid supply tube 21a made of synthetic resin, rubber, or metal, etc., connected to a liquid supply source (not shown). The type of liquid supply is not limited and can be any known type, such as drip type or sprinkler type. The liquid supply temperature sensor 22 measures the temperature of the culture solution supplied from the liquid supply unit 21 and is supported by a sensor support frame 22c, as shown in Figures 3(a) and (b). The sensor support frame 22c is formed in a substantially box shape with a sensor placement hole 22d and has legs 22e that protrude downward. The sensor support frame 22c also has a cylindrical tube tip support part 22f that supports the area near the discharge port 21b located at the tip of the liquid supply tube 21a that constitutes the liquid supply unit 21. The tube tip support portion 22f is provided adjacent to the sensor placement hole 22d, and when the area near the discharge port 21b is inserted into the tube tip support portion 22f, the culture medium discharged from the discharge port 21b can come into contact with the temperature sensing portion 22a of the liquid supply temperature sensor 22 located in the sensor placement hole 22d.

[0029] The sensor support frame 22c is positioned, for example, by inserting its legs 22e into the seedling culture medium 2b. This allows the temperature of the culture solution to be measured when it is supplied to the seedling culture medium 2b from the supply unit 21. The supply temperature sensor 22 can be a thermocouple, thermistor, or the like, similar to the drainage temperature sensor 12 described above.

[0030] The liquid supply determination unit 23 receives measurement data from the liquid supply temperature sensor 22 and determines the timing at which a temperature change exceeding a predetermined level is detected as the liquid supply timing. Similar to the drainage temperature sensor 12, the detection of a temperature change exceeding a predetermined level by the liquid supply temperature sensor 22 may be detected as a temperature decrease or temperature increase depending on the season. Similar to the drainage determination unit 13 described above, the liquid supply determination unit 23 can be composed of a control panel including an electrical circuit that can receive measurement data from the liquid supply temperature sensor 22 and determine a temperature change exceeding a predetermined level in said measurement data, or a computer on which a computer program that performs such a function is installed. Note that the liquid supply determination unit 23 and the drainage determination unit 13 may be separate, or they may be set up on the same control panel or computer as shown in Figure 5. Figure 5 schematically shows the product name "ProFinder (registered trademark)" 50 manufactured by Seiwa Co., Ltd., which is a device that measures greenhouse environmental factors such as temperature, humidity, solar radiation, and carbon dioxide, but the liquid supply determination unit 23 and the drainage determination unit 13 can be incorporated into this ProFinder 50.

[0031] According to the irrigation management system 100 of this embodiment, when the culture solution (supplied solution) supplied from the discharge port 21b of the liquid supply unit 21 comes into contact with the temperature sensing element 22a of the liquid supply temperature sensor 22, the detected temperature of the liquid supply temperature sensor 22, which had been showing a temperature close to the ambient temperature inside the greenhouse, changes. The liquid supply determination unit 23 detects the timing of liquid supply based on this information. The supplied culture solution spreads throughout the culture medium, is discharged from the culture medium 2, and reaches the retention area 11d of the culture medium support frame 11 as drainage. The drainage temperature sensor 12, whose temperature sensing element 12a is located in the retention area 11d, changes its detected temperature upon contact with the drainage. This confirms that drainage occurred after a predetermined time had elapsed since liquid supply, that is, that the culture solution had spread throughout the culture medium 2. Therefore, according to this irrigation management system 100, it is possible to know situations where drainage is not detected despite liquid supply, or the time interval between the timing of liquid supply and the timing of drainage detection. As a result, it becomes possible to know the state of irrigation and drainage over time, enabling more detailed irrigation management.

[0032] Furthermore, as shown in Figures 3(a) and 3(b), it is preferable to provide a heating member 24 near the temperature sensing part 22a of the liquid supply temperature sensor 22, which is connected to a heating power supply via a sensor support frame 22c, similar to the drainage temperature sensor 12. More preferably, the heating member is set to a temperature equal to or higher than the highest of the drainage temperature, liquid supply temperature, and ambient temperature inside the greenhouse. As a result, when the drainage liquid comes into contact with the temperature sensing part 22a of the liquid supply temperature sensor 22, a significant temperature drop will occur, similar to the case of the drainage temperature sensor 12.

[0033] (Experimental Example 1) As shown in Figure 5, the liquid supply unit 21 (drip tube) was placed in the seedling culture medium 2b of culture medium 2, and the temperature sensing part 22a of the liquid supply temperature sensor 22 was positioned near the outlet of the liquid supply unit 21 to measure the liquid supply temperature. The liquid supply conditions were as follows. The cultivated plant was a tomato.

[0034] a) Between 1 hour 30 minutes and 5 hours 30 minutes after sunrise: Solar radiation 60 J / cm² 2 One injection each time b) Between 5 hours 30 minutes and 9 hours after sunrise: Solar radiation of 100 J / cm² 2 One injection each time c) Between 9 hours after sunrise and 1 hour and 45 minutes before sunset: Solar radiation 110 J / cm 2 One injection each time (However, regardless of the cumulative solar radiation, the minimum waiting time for liquid supply is 23 minutes.)

[0035] Furthermore, a drainage temperature sensor 12 was provided so that its temperature sensing element 12a could come into contact with the drainage passing through the stagnant portion 11d of the drainage support frame 10. In this experimental example, neither the supply temperature sensor 22 nor the drainage temperature sensor 12 were equipped with heating members 24 and 14. The results are shown in Figure 6.

[0036] Figure 6 shows the measurement data from the drainage temperature sensor 12 and the supply temperature sensor 22. As shown in this figure, the drainage temperature and supply temperature show a daily trend that follows the change in the indoor temperature of the greenhouse.

[0037] However, when comparing the temperature before and after irrigation, the irrigation temperature remained almost constant after each of the first, second, third, and fourth irrigations, showing a different trend from the rising ambient temperature inside the greenhouse. The drainage temperature showed no change after the first irrigation. A temperature drop occurred after the third irrigation, and a temperature drop occurred with each subsequent irrigation. From this, we can see that no drainage occurred after the first fluid infusion, drainage occurred after the third fluid infusion, and drainage has occurred after every subsequent fluid infusion. In general, the ideal irrigation management involves ensuring no drainage occurs after the first application, some drainage occurs after the second application, and sufficient drainage occurs after the third application. According to the measurement data in Figure 4, drainage occurs from the third application onward, confirming that irrigation management was performed in a manner close to ideal. Furthermore, it is recommended to irrigate in a way that drainage occurs during the time when the instantaneous solar radiation reaches approximately 500W. In the greenhouse where Experiment Example 1 was conducted, the instantaneous solar radiation reached 500W at 7:50 AM on July 2, 2024, and it was also observed that drainage occurred before that time.

[0038] Thus, as shown in Experimental Example 1, by detecting changes in drainage temperature, it is possible to easily grasp the daily changes in whether appropriate fluid supply management is being carried out. Based on these experimental results, the drainage detection unit 13 sets a threshold for the level of decrease in drainage temperature, and by detecting the measurement data from the drainage temperature sensor 12, it can automatically determine when drainage has occurred and output a corresponding message. The same applies to the supply detection unit 23; by setting a threshold for the level of decrease in supply temperature, it can automatically determine the timing of supply from the measurement data from the supply temperature sensor 22. By detecting the timing of supply and drainage, the supply detection unit 23 and the drainage detection unit 13 can determine, based solely on temperature changes, which supply cycle of the day caused the drainage, making it easy to determine whether proper irrigation management is being carried out.

[0039] (Experimental Example 2) In Figure 6, which shows the measurement data for Experimental Example 1, the change in the supply liquid temperature is small around 8-11 am and 12-6 pm. Similarly, the change in the drained liquid temperature is small around 12-6 pm. When the change is small in both the drained liquid determination unit 13 and the supply liquid determination unit 23, it becomes difficult to determine the timing of both drainage and supply.

[0040] Therefore, in Experiment Example 2, the experiment was conducted with a configuration in which resistance-type heaters were installed as heating elements 14 and 24 near the temperature sensing parts 12a and 22a of the drainage temperature sensor 12 and the supply temperature sensor 22, respectively. The heating elements 14 and 24 were used to adjust the temperature of the drainage temperature sensor 12 and the supply temperature sensor 22 to be constantly 20 to 40°C, preferably 25 to 35°C, higher than the ambient temperature inside the greenhouse, and irrigation was carried out. Note that Experiment Example 2 was conducted on the same day as Experiment Example 1, but in a different cultivation bed (a culture medium support frame 11 supporting the culture medium 2 was used as one cultivation bed).

[0041] Figure 7 shows the measurement data from the drainage temperature sensor 12 and the supply temperature sensor 22 in Experimental Example 2, along with the ambient temperature inside the greenhouse. Figure 7 shows that the supply fluid temperature decreased significantly at 5:57, 6:40, 7:10, 7:35, etc., clearly indicating that fluid supply was performed at these times. The drain fluid temperature first decreased after 7:15, indicating that drainage occurred immediately after the third fluid supply. Subsequently, drainage occurred with each fluid supply. Even after 8:00, when the change was small in the data from Experimental Example 1, significant temperature changes occurred in both the supply fluid temperature and the drain fluid temperature. Therefore, according to Experimental Example 2, it is possible to clearly detect the occurrence of drainage even during periods when the temperature inside the greenhouse is rising.

[0042] Furthermore, because the temperature change is large, it is easy to set a threshold for the temperature change level in both cases where drainage occurs and when liquid is supplied, improving the accuracy of the drainage timing and liquid supply timing determination by the drainage determination unit 13 and the liquid supply determination unit 23.

[0043] (Experimental Example 3) Similar to Experimental Example 2, an irrigation experiment was conducted using an irrigation management system 100 equipped with heating elements 14 and 24 attached to the drainage temperature sensor 12 and the supply temperature sensor 22. Supply of liquid was performed simultaneously not only on the culture medium supported by the culture medium support frame 11 in Experimental Example 3, but also on several other culture media. A weight sensor, Priva Groscale, was also installed on two of the other culture media to sequentially measure their weight, and the weight change per culture medium was determined and used as a comparative example. The irrigation management system 100 is designed to output a liquid supply signal when supplying liquid. The results are shown in Figures 8 and 9.

[0044] Figure 8 shows the measurement results on July 6, 2024. First, the timing of the liquid supply signal and the temperature drop detected by the liquid supply temperature sensor 22 are almost synchronized, indicating that the liquid supply temperature sensor 22 in this embodiment accurately detects the liquid supply timing. The drainage temperature sensor 12 detects a decrease in drainage temperature for the first time after detecting that the third liquid supply has been performed. Subsequently, a decrease in drainage temperature is detected each time liquid is supplied, indicating that the culture medium 2 is constantly supplied with culture solution throughout the day.

[0045] Weight Sensor: Weight detection using Priva Groscale shows that the weight increases until the third liquid supply, but remains almost constant thereafter until the liquid supply is stopped. Therefore, it can be inferred that drainage occurs after the third liquid supply, and thereafter drainage occurs with each liquid supply. The detection of drainage by the weight sensor and the detection of drainage using the drainage temperature sensor 12 of this embodiment are consistent, indicating that the means of detecting temperature changes of the drainage in this embodiment is effective in detecting the timing of drainage. On the other hand, the weight sensor shows an almost constant detection value after the initial drainage, leading to the determination that drainage occurs with each liquid supply. However, because the detection value is constant or fluctuates very little, it can be difficult to reliably determine whether drainage is occurring with each liquid supply. In contrast, according to this embodiment, in particular, by configuring the drainage temperature sensor 12 to be heated by the heating member 14, a significant temperature change is obtained during drainage, and it is possible to reliably detect whether drainage is occurring with each liquid supply.

[0046] Figure 9 shows the measurement results from July 8, 2024. In this case, the results are almost the same as in Figure 8, but with the weight sensor, the weight remains almost constant after the fourth liquid supply, allowing it to be determined that drainage occurred on the fourth supply. In contrast, with the measurement data from the drainage temperature sensor 12, it can be determined that the first drainage occurred after the third liquid supply. This is because the amount of drainage that occurred after the third liquid supply was small. With the weight sensor, it is difficult to detect a change in weight when the amount of drainage is below a predetermined amount, whereas with the drainage temperature sensor 12, a temperature change occurs when the drainage comes into contact with the temperature sensing part 12a, so even a smaller amount of drainage can be detected. This demonstrates that despite its simple configuration, it has high accuracy in detecting the timing of drainage.

[0047] Next, an irrigation management system 100 of another embodiment of the present invention will be described based on Figures 10 to 12. Depending on factors such as the type of plant to be cultivated, the cultivation method, or the scale of cultivation, a long cultivation bed (a culture medium support frame 11 supporting the culture medium 2) is used, for example, one that is 5 m to several tens of m long. In such cases, an irrigation tube 211 with a length approximately equal to the length of the cultivation bed is laid on the culture medium 2, and one end of the tube 211 is connected via a pipe joint 210a to a liquid supply pipe 210 made of metal or hard plastic that is connected to a liquid supply source (a culture medium tank, etc. (not shown)). In this embodiment, the liquid supply section 21 includes the liquid supply pipe 210 and the irrigation tube 211, but in this case, the cost would increase if a liquid supply temperature sensor 22 were placed at each discharge port opened at predetermined intervals in the irrigation tube 211. Therefore, in this embodiment, the liquid supply temperature sensor 22 is attached to the liquid supply pipe 210, simplifying the overall configuration. In this embodiment, the culture medium support frame 11 is installed at a predetermined height by leg members 11h, and the liquid supply pipe 210 is piped to rise upward so as to reach the height of the irrigation tube 211 located at a predetermined height from the liquid supply source.

[0048] As shown in Figures 10 and 11(a), the liquid supply temperature sensor 22 is fixed to the pipe joint 210a, which is part of the liquid supply pipe 210, via a sensor support frame 22c in this embodiment. Specifically, a through hole is formed in the pipe joint 210a into which the temperature sensing element 22a can be inserted, and the temperature sensing element 22a is positioned to face the inside of the pipe joint 210a through this through hole. In this state, the sensor support frame 22c is fixed to the outer surface of the pipe joint 210a. The temperature sensing element 22a is inserted to a position where it can come into contact with the culture medium passing through the inside of the pipe joint 210a.

[0049] Regarding drainage, a drainage hole 11e is provided at one longitudinal end of the culture medium support frame 11, which is positioned at a predetermined height to support the culture medium 2. A drainage pipe 11g, made of metal or hard plastic, is connected to this drainage hole 11e so as to extend downward from the culture medium support frame 11 (see Figures 10 and 12). In this embodiment, the drainage path includes the inner region of the support frame 11 through which the drainage discharged from the culture medium 2 passes, as well as the drainage hole 11e and the drainage pipe 11g. When the cultivation bed, consisting of the culture medium 2 and the culture medium support frame 11, is several tens of meters long as described above, the cultivation bed is arranged with a predetermined incline so that the drainage collects in the drainage hole 11e formed at one longitudinal end.

[0050] As shown in Figure 11(c), the drainage temperature sensor 12 is installed by inserting a predetermined amount of the temperature sensing element 11a into the drainage pipe 11g through a through-hole formed in the middle of the drainage pipe 11g. However, if the drainage pipe 11g is installed vertically, the drainage passing through the drainage pipe 11g does not flow unevenly to any particular area of ​​the inner circumference. Therefore, in this embodiment, a drainage restricting member 110 is provided inside the drainage pipe 11g to restrict the flow of drainage.

[0051] As shown in Figures 11(b) and (c), the drainage regulating member 110 is configured with a receiving tray portion 111 comprising an annular bottom surface 111a, an outer cylindrical portion 111b rising from the outer circumference of the annular bottom surface 111a, and an inner cylindrical portion 111c rising from the inner circumference of the annular bottom surface 111a. A support rod 112 is erected at the upper end opening of the inner cylindrical portion 111c, and a baffle plate 113 is supported at the upper end of this support rod 112. The diameter of the baffle plate 113 shown in the figure is approximately the same as that of the inner cylindrical portion 111c, but any size can be used as long as it is greater than or equal to the diameter of the inner cylindrical portion 111c and less than the diameter of the outer cylindrical portion 111b. In addition, a drain port 111d is opened at one location on the annular bottom surface 111a.

[0052] The drainage temperature sensor 12 is inserted through a through-hole formed in the peripheral wall of the drainage pipe 11g so that the temperature sensing part 12a is located directly below the drain outlet 111d, and the sensor support frame 12c is fixed to the outer surface of the drainage pipe 11g.

[0053] The drainage liquid flowing from the drainage hole 11e of the culture medium support frame 11 through the drainage pipe 11g is restricted by the baffle plate 113 within the drainage pipe 11g and accumulates between the outer cylindrical portion 111b and the inner cylindrical portion 111c of the receiving tray 111. As a result, the drainage liquid falls towards the temperature sensing portion 12a of the drainage temperature sensor 12 via the drain port 111d, allowing the temperature of the drainage liquid to be measured. When the amount of drainage liquid accumulated between the outer cylindrical portion 111b and the inner cylindrical portion 111c exceeds the height of the inner cylindrical portion 111c, the overflowing drainage liquid flows downstream of the drainage regulating member 110 via the inside of the inner cylindrical portion 111c.

[0054] According to this embodiment, even when the cultivation bed is long and the length of the irrigation tube 211 is also long, by measuring the supply temperature in the supply pipe 210 that supplies culture solution to the tube 211 and measuring the drainage temperature in the drainage pipe 11g through which the drainage solution passes, the equipment required to measure the supply temperature and drainage temperature (supply temperature sensor 22, drainage temperature sensor 12, etc.) can be minimized, contributing to equipment simplification and cost reduction.

[0055] (Experimental Example 4) As shown in Figures 10 to 12, a liquid supply temperature sensor 22 was installed at the pipe joint 210a of the liquid supply pipe 210, and a drainage temperature sensor 12 was installed at the drainage pipe 11g, and the liquid supply temperature and drainage temperature were measured. The results are shown in Figure 13. The supply liquid temperature changes in sync with the supply liquid signal, and the timing of the supply liquid is determined by the change in the supply liquid temperature. The drain liquid temperature sensor 12 also shows a decrease in the drain liquid temperature due to contact with the drain liquid, but the amount of change is small.

[0056] On the other hand, Figure 14 shows data when both the liquid supply temperature sensor 22 and the drainage temperature sensor 12 are heated to approximately 20 degrees Celsius above the ambient temperature inside the greenhouse. As shown in Figure 14, a significant temperature drop is detected each time liquid is supplied, and a significant temperature drop is detected each time drainage occurs, slightly later than the liquid supply. The timing of the temperature drop is synchronized with the timing of the liquid supply signal, and in this embodiment as well, by detecting the temperature drop, it is possible to accurately detect when liquid supply and drainage have occurred.

[0057] As mentioned above, this embodiment is effective when the cultivation bed is long, such as several tens of meters or more. However, even in short cultivation beds of about 1 to 4 meters, as shown in Figures 3 to 5, by using a configuration with the same liquid supply pipe 210 and drainage pipe 11g as in this embodiment, it is possible to measure the temperature of the culture solution passing through them and the temperature of the drainage to detect the timing of liquid supply and drainage.

[0058] Furthermore, as shown in Figure 15, even when multiple short cultivation beds of about 1 to 4 m are installed in a continuous manner along their longitudinal direction, a liquid supply unit 21 with a configuration similar to that shown in Figure 10 may be adopted, in which an irrigation tube 211 is laid so as to straddle each cultivation bed, and one end of the tube 211 is connected to a single liquid supply pipe 210. In this case as well, one liquid supply temperature sensor 22 is sufficient, provided on the liquid supply pipe 210. On the other hand, a drain pipe 11g is provided for each cultivation bed. Therefore, it is preferable to provide a drain temperature sensor 22 for each drain pipe 11g, as shown in Figure 15. With such a configuration, the equipment for measuring the liquid supply temperature can be minimized, while a signal indicating a temperature drop can be detected by the drain temperature sensor 22 for each cultivation bed, allowing for detailed management of each cultivation bed.

[0059] However, in order to simplify the configuration and reduce costs, it is also possible to install a drainage temperature sensor 22 only in the drainage pipe 11g of one cultivation bed, and to determine the presence or absence of drainage based on the temperature change.

[0060] In the above embodiment, a method of heating the drainage temperature sensor 12 and the supply temperature sensor 22 is described in order to measure temperature changes more clearly. However, as described above, temperature changes detected by the drainage temperature sensor 12 and the supply temperature sensor 22 may be detected as a temperature rise depending on the season, etc. In such cases, it is also possible to replace the heating members 14 and 24 that preheat the drainage temperature sensor 12 and the supply temperature sensor 22 with a known cooling member (not shown) and pre-cool them to a predetermined temperature to clearly capture temperature rise changes.

[0061] Furthermore, in the above embodiment, the legs 22e of the sensor support frame 22c are inserted into the seedling growing medium 2b. However, as shown in Figure 16, a liquid supply passage 22g can be provided in the sensor support frame 22c, and the temperature sensing part 22a of the liquid supply temperature sensor 22 can be positioned to face this liquid supply passage 22g. In this case, the liquid supply tube 21a is divided, one divided liquid supply tube 21a1 is connected to the inlet side of the liquid supply passage, and the other divided liquid supply tube 21a2 is connected to the outlet side of the liquid supply passage 22g. The end of the other liquid supply tube 21a2 is then placed on the seedling growing medium 2b or the growing medium 2. With this configuration, the sensor support frame 22c with the liquid supply passage 22g and the liquid supply temperature sensor 22 can be attached to, for example, the growing medium support frame 11, without any restrictions on the mounting position, making it convenient.

[0062] Figure 17 shows an overview of yet another embodiment of the present invention, and Figures 18 and 19(a) to (c) show the configuration of its main parts. This embodiment is similar to the embodiments shown in Figures 10 to 12 and 15 in that the liquid supply section 21 has a liquid supply pipe 210 made of metal or hard plastic, but as shown in Figures 17 and 18, the mechanism for measuring the temperature of the culture medium passing through the liquid supply pipe 210 is separated from the liquid supply pipe 210. That is, a branch pipe 210b is provided at an arbitrary part of the liquid supply pipe 210, for example, at a pipe joint 210a. The branch pipe 210b can be made of a flexible tube or the like, and a liquid supply temperature sensor 22 supported by a sensor support frame 22c is placed at the outlet located at the end of the branch pipe 210b.

[0063] When liquid supply is started, a portion of the liquid flows into the branch pipe 210b, so the temperature detected by the liquid supply temperature sensor 22 is the temperature of the culture medium passing through the liquid supply pipe 210. Because the branch pipe 210b is provided and the liquid supply temperature sensor 22 is installed in the branch pipe 210b, the constraints on the placement of the liquid supply temperature sensor 22 are reduced compared to the embodiments shown in Figures 10-12 and 15.

[0064] Furthermore, in the embodiments shown in Figures 10-12 and 15, a drainage regulating member 110 having a baffle plate 113 and a receiving tray portion 111 is provided inside the drainage pipe 11g as a mechanism for measuring the temperature of the drainage liquid inside the drainage pipe 11g, and the temperature sensing part 12a of the drainage temperature sensor 12 is positioned below the drain port 111d of the receiving tray portion 111. For this reason, the drainage temperature sensor 12 must be positioned inside the drainage pipe 11g in a position approximately perpendicular to the drainage pipe 11g, and the temperature sensing part 12a must be in contact with the drainage liquid flowing down from the drain port 111d of the receiving tray portion 111, making adjustment of the mounting position troublesome.

[0065] In contrast, in this embodiment, instead of the drainage restricting member 110 described above, the drainage restricting member 1100 shown in Figures 17 and 19(a) to (c) is used. The drainage restricting member 1100 of this embodiment is positioned in the middle of the drainage pipe 11g and has a large diameter receiving tray portion 1110 that is larger in diameter than the drainage pipe 11g and protrudes outward. A baffle plate 1113 is provided near the center of the large diameter receiving tray portion 1110, and an inner circumferential cylindrical portion 1111c is provided below the baffle plate 1113. A partition wall portion 1111e is provided between the inner circumferential cylindrical portion 1111c and the outer circumferential cylindrical portion 1111d of the large diameter receiving tray portion 1110. A notch portion 1111f is formed in the partition wall portion 1111e, and a drain port 1111g is provided between the notch portion 111f and the outer circumferential cylindrical portion 1111d. The baffle plate 1113 is positioned inside the drain pipe 11g, and the portion from the partition wall 1111e to the outer cylindrical portion 1111d is positioned to protrude outward from the drain pipe 11g.

[0066] The drainage flowing through the drain pipe 11g hits the baffle plate 1113 and flows outwards, but once a predetermined amount has flowed, it goes over the upper end of the inner circumferential cylindrical portion 1111c and enters the inner circumferential cylindrical portion 1111e, and continues to flow through the drain pipe 11g, while a portion flows towards the outer circumferential cylindrical portion 1111d through the notch portion 1111f, and in between flows into the drain port 1111g and flows downward through the drain pipe 11g.

[0067] When the drainage flows from the notch 1111f to the drain port 1111g, the drainage moves in a substantially horizontal direction, so the temperature sensing part 12a of the drainage temperature sensor 12 is positioned so that it is in contact with the drainage flowing between them. In this case, the drainage temperature sensor 12 can be positioned in a substantially vertical position outside the drainage pipe 11g, so the sensor support frame 12c shown in Figure 1, on which the drainage temperature sensor 12 is supported in a substantially vertical position, can be used as is. Since the temperature sensing part 12a of the drainage temperature sensor 12 only needs to be positioned so that it is in contact with the drainage flowing outside the drainage pipe 11g, the installation work of the drainage temperature sensor 12 is easier compared to the embodiments in Figures 10-12 and 15. [Explanation of Symbols]

[0068] 1. Drainage management device 11. Culture medium support frame 11d Retention part 12. Drainage temperature sensor 12a Temperature sensing element (of the drainage temperature sensor) 13. Drainage detection unit 14 (For drainage temperature sensor) Heating component 21 Liquid supply section 22. Temperature sensor for liquid supply 22a Temperature sensing element (of the liquid supply temperature sensor) 23 Liquid supply judgment section 24 (For liquid supply temperature sensor) Heating member 100 Irrigation Management Systems

Claims

1. A drainage temperature sensor is installed in the drainage path of the drainage liquid discharged from the growing medium in which the plants to be cultivated are planted, and is capable of measuring the temperature of the drainage liquid. A drainage determination unit receives measurement data from the drainage temperature sensor and determines the timing at which a temperature change exceeding a predetermined level is detected as the drainage timing at which the drainage occurred. A drainage management device for hydroponic cultivation.

2. The medium has a medium support frame for supporting the medium, and the medium support frame is provided with the discharge path. In the aforementioned discharge path, a retention section is provided where the drained liquid temporarily remains. The temperature-sensing portion of the drainage temperature sensor is provided in the retention portion so as to be in contact with the drainage. A drainage management device for hydroponic cultivation according to claim 1.

3. The aforementioned discharge path is configured to include a drain pipe, The drainage temperature sensor is provided such that the temperature sensing element is located inside the drainage pipe. An guiding member is provided in the drain pipe upstream of the location where the temperature-sensing part is located, to guide the drain liquid to come into contact with the temperature-sensing part. A drainage management device for hydroponic cultivation according to claim 1.

4. A heating member is provided to heat the drainage temperature sensor. A drainage management device for hydroponic cultivation according to claim 1.

5. A drainage management device according to any one of claims 1 to 4, A supply unit that provides nutrient solution to the plants to be cultivated, A temperature sensor for supplying the culture medium, capable of measuring the supplying temperature of the culture medium, A liquid supply determination unit receives measurement data from the liquid supply temperature sensor and determines the timing at which a temperature change exceeding a predetermined level is detected as the liquid supply timing when the liquid was supplied. An irrigation management system for hydroponic cultivation.

6. A heating member is provided to heat the aforementioned liquid supply temperature sensor. The irrigation management system for hydroponic cultivation according to claim 5.

7. The aforementioned liquid supply temperature sensor has a temperature sensing element located near the discharge port of the liquid supply unit, and measures the temperature of the culture medium discharged from the discharge port as the liquid supply temperature. The irrigation management system according to claim 5.

8. The temperature sensor for supplying the culture medium has a temperature sensing element located inside the supplying pipe that constitutes the supplying section, and measures the temperature of the culture medium passing through the supplying pipe as the supplying temperature. The irrigation management system according to claim 5.

9. A drainage temperature sensor, installed in the drainage path of the growing medium in which the target plants are planted, is capable of measuring the temperature of the drainage liquid. When the sensor detects a temperature change exceeding a predetermined level, it manages whether or not drainage has occurred, indicating the timing of the drainage. Methods for managing drainage in hydroponic cultivation.

10. The drainage temperature sensor is preheated, and the temperature of the drainage is measured. A method for managing drainage in hydroponic cultivation according to claim 9.

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