JP2017221150A - Plant cultivation device and irrigation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fundamentally prevent the formation of a root mat and achieve optimal irrigation by bottom side irrigation.SOLUTION: A plant cultivation device 1 carries out bottom side irrigation of soil 12 with water from a water storage tank (water storage vessel) 13 by capillary action from a sheet-like irrigation cloth 11 laid on the bottom side of a plant cultivation vessel 10 with an inclined bottom part. Depending on the irrigation, a float switch 14 acting as a water level sensor detects a decrease in the water level of the water storage tank 13 and on the basis thereof an auxiliary irrigation device 15 performs auxiliary irrigation on the soil 12 from above the plant cultivation vessel 10. Accordingly, a water retaining region R is formed in the vicinity of the roots of a cultivated plant P, and excess water not used in the formation thereof flows down the incline of the plant cultivation vessel 10 into the water storage tank 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a plant cultivation apparatus that performs bottom surface irrigation by capillary action of an irrigation sheet and an irrigation control method using the same.

  When cultivating plants in a plant cultivation container such as a planter, the bottom irrigation draws water from the water storage tank located several centimeters below the soil in the container by the capillarity of a strong irrigation cloth and irrigates the soil. (Water supply) is known (see, for example, Patent Documents 1 and 2). This method is an excellent irrigation method because water can be supplied in an amount corresponding to the amount of water absorbed by the plant while maintaining the air permeability of the soil surface.

JP-A-10-127177 JP 2012-170350 A

  However, in the bottom irrigation as described in Patent Documents 1 and 2, water absorption is achieved by forming a root mat where the roots are concentrated on the irrigation cloth surface due to an increase in the amount of water absorption accompanying plant growth (see FIG. 4). There was a problem that the ability was significantly reduced. As a result, wilting may occur under hot weather, and in the worst case, there was a risk of death. This has been a problem for many years in the bottom irrigation and has been a major factor of lack of reliability.

  Here, in principle, there are a method of obtaining the evapotranspiration from a change in the weight of the soil-plant system, a method of obtaining from the ventilation amount and absolute humidity of the inlet and outlet in the plant space isolated in the chamber, and the like.

  However, each method is not practical because it requires precise equipment, etc. In normal facility cultivation, for example, timer control, solar radiation control, soil moisture sensor control, etc. Has been done.

  Among them, in the timer control, even if the weather and the state of the plant are different, a certain amount of irrigation is periodically performed. In the solar radiation control, only the weather condition is considered, and it cannot cope with the size of the plant body or its growth state. In the control by the soil moisture sensor, the soil moisture changes spatially, and the measured value cannot be a value representative of the whole. In fact, there is a finding that more than 10 points of measurement data are required to grasp soil moisture at the 1% level (1951 paper by Aitchison et al.).

  On the other hand, measures to prevent the formation of the root mat include, for example, a method of preventing root invasion by partially opening the irrigation cloth into the atmosphere, and suppressing root concentration by injecting chemicals into the winding cloth. Various attempts have been made, such as a method for automatically compensating for the deficient soil moisture by changing the water absorption mutation by a program. However, all of these attempts are coping therapy workarounds, and could not be a solution for fundamentally solving the formation of root mats related to plant physiology.

  An object of the present invention is to fundamentally prevent the formation of a root mat and realize optimum irrigation by bottom surface irrigation.

  <1> A plant cultivation container having an inclined bottom, an irrigation sheet laid on the bottom surface of the container, soil in which the plant to be cultivated and planted is planted, and an inclined lower end side of the cultivation container A water storage container in which the irrigation sheet is inserted to perform bottom irrigation of the soil through the capillary action of the irrigation sheet, a water level sensor provided in the water storage container, and the water level sensor A plant cultivation device comprising: an auxiliary irrigation device for further irrigating the soil from above the plant cultivation vessel based on a decrease in the water level of the water storage vessel.

  <2> The plant cultivation apparatus according to <1>, wherein a root-proof permeable sheet is laid on the irrigation sheet.

  <3> The irrigation by the auxiliary irrigation device is performed through a irrigation tube, and a tip region of the irrigation tube is inserted in the vicinity of a root of the plant in which the soil is planted. <1> or <2> Plant cultivation equipment.

  <4> The plant according to any one of <1> to <3>, wherein the irrigation amount is adjusted according to a set value of a water level change amount detected by the water level sensor and a depth of the soil into which the auxiliary irrigation device is inserted. It is a cultivation device.

  <5> An irrigation control method using the plant cultivation apparatus according to any one of <1> to <4>, wherein (a) the irrigation sheet performs irrigation on the bottom surface, and (b) the water level by the irrigation. A step in which a sensor detects a decrease in the water level of the water storage container; and (c) based on the detected decrease in the water level of the water storage container, the auxiliary irrigation device further irrigates the soil, and the soil is planted. A irrigation control method comprising the steps of: forming a water retention region around the root of the plant; and (d) a step of surplus water not used for forming the water retention region flowing into the water storage container. is there.

  <6> (e) a step in which the water level sensor detects an increase in the water level of the water storage container due to the inflow of the surplus water; and (f) the auxiliary irrigation device is irrigated based on the detected increase in the water level of the water storage container. The irrigation control method according to <5>, further comprising:

  <7> The irrigation control method according to <6>, wherein the irrigation of the auxiliary irrigation device is based on the fact that the water level sensor detects the rise of the water storage container to the initial water level.

  In the plant cultivation device of the present invention, a water retention area is formed in the soil where the plant to be cultivated is planted from the bottom irrigation through the capillary phenomenon of the irrigation sheet and the auxiliary irrigation from above the auxiliary irrigation device. The roots that can absorb water greatly expand, and the formation of the root mat is fundamentally prevented. Thereby, optimal irrigation is realizable by bottom surface irrigation.

  Since the irrigation control method of the present invention performs irrigation control using the plant cultivation apparatus of the present invention, formation of the root mat is fundamentally prevented, and optimal irrigation can be realized by bottom surface irrigation.

FIG. 1 is a schematic configuration diagram of a plant cultivation apparatus according to the present invention. FIG. 2 is a graph showing changes over time in measured water absorption and atmospheric water potential (physical model) when the plant cultivation apparatus of the present invention is used. FIG. 3A is a graph showing measured data of solar radiation intensity, temperature, and soil moisture content when the plant cultivation apparatus of the present invention is used, and FIG. 3B is a graph showing the accumulated irrigation amount. . FIG. 4 is a photograph of an example of the formed route mat.

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a plant cultivation apparatus according to the present invention. As shown in FIG. 1, a plant cultivation apparatus 1 according to the present invention includes a plant cultivation container 10, a sheet-like irrigation cloth 11, soil 12, and A water storage tank (water storage container) 13, a float switch 14 as a water level sensor, and an auxiliary irrigation device 15 are mainly configured. The auxiliary irrigation device 15 includes an irrigation tank 20, a pump 21, and a tubular irrigation pipe 22.

  The plant cultivation container 10 is a container-like planter in the illustrated example, and the bottom is formed in an inclined shape. In addition, this plant cultivation container 10 may use a pot etc. according to the objectives, such as the scale of the plant to grow.

  The irrigation cloth 11 is laid along the bottom surface of the plant cultivation container 10 and the side surface on the inclined upper end side. On the upper surface of the irrigation cloth 11, a root-permeable permeable cloth 25 is laid to prevent the root of the plant to be cultivated from entering the irrigation cloth 11. In the illustrated example, the root-proof permeable cloth 25 is also laid on the side surface on the inclined lower end side of the plant cultivation container 10 where the irrigation cloth 11 is not laid.

  The soil 12 is put in a cultivation container 10 in which the irrigation cloth 11 and the root-permeable permeable cloth 25 are laid, and a plant P to be cultivated on the soil 12 is planted.

  The water storage tank 13 is provided on the inclined lower end side of the plant cultivation container 10, and the lower end of the irrigation cloth 11 is inserted and immersed in the water in the tank. A float switch 14 is provided in the water storage tank 13.

  A irrigation pipe 22 is connected to the irrigation tank 20 constituting the auxiliary irrigation apparatus 15, and the tip region of the irrigation pipe 22 is cultivated from the upper side of the plant cultivation container 10, preferably as shown in FIG. It is inserted in the vicinity of the root of the plant P to be made to a depth t set appropriately. In addition, the vicinity of a root should just be a position where the grower who uses this apparatus judges visually close to a root, and a specific dimension range is not ask | required.

  The water in the irrigation tank 20 is supplied to the irrigation pipe 22 by the pump 21. The pump 21 is electrically connected to the float switch 14 by wire or wireless.

  The plant cultivation apparatus 1 acts as in the following (a) to (f) by the above-described configuration, and irrigation is controlled.

  (A) When a negative pressure is generated in the soil 12, the bottom irrigation of the water in the water storage tank 13 is performed on the soil 12 due to the capillary action of the irrigation cloth 11.

  (B) Although the water level of the tank 13 falls by this irrigation, the float switch 14 detects when the water level change exceeds the set value s.

  (C) Using the detection of the water level change by the float switch 14 as an operation signal, the pump 21 of the auxiliary irrigation device 15 is operated, and the irrigation pipe 22 irrigates the soil 12, thereby surrounding the root of the plant P to be cultivated. A water retention region R is formed.

  (D) If this irrigation is continued, the water retention area | region R will be fully formed and the surplus water which is not used for the formation will arise. This excess water flows on the irrigation cloth 11 due to the inclination of the bottom of the plant cultivation container 10 and flows into the water storage tank 13.

  (E) When the water level rise due to this inflow returns to the set value s, that is, the initial water level, the float switch 14 detects the change in the water level.

  (F) The pump 21 of the auxiliary irrigation device 15 stops using the detection of the water level change by the float switch 14 as a stop signal, and the irrigation to the soil 12 by the irrigation pipe 22 is terminated.

  By the action of the plant cultivation container 1 of the present invention, the water retention region R formed around the root of the plant P to be cultivated is the cultivation container 10 by the capillary water supplied by the bottom irrigation from the irrigation cloth 11 and the irrigation pipe 22. It becomes the area | region which makes the three-dimensional structure by gravity water irrigated auxiliary from above. Therefore, the range in which the plant P to be cultivated can drastically increase, so that the formation of the root mat is suppressed and the structural problem that the root mat is formed in the bottom irrigation is solved.

  The root mat formation is due to the positive hydrotropism of the roots. That is, since the root has the ability to sense the amount of water, it exhibits positive water tropism. The degree of water tropism is generally proportional to the soil water gradient (“Root Dictionary” Asakura Shoten 1998, pp. 65-66). Therefore, as in the present invention, an arbitrary water retention area is formed in the soil space, a three-dimensional water gradient is generated, and the roots of the plant are induced and dispersed spatially there, thereby allowing roots to be placed on the irrigation cloth. It is possible to prevent the formation of a root mat that is densely packed two-dimensionally.

  Further, the water remaining in the formation of the water retention region R flows on the irrigation cloth 11 on the bottom surface of the plant cultivation container 10 and flows into the water storage tank 13 to restore its water level. The water retention amount of the soil 12 can be constantly maintained while taking advantage of the ability to irrigate a suitable amount of water, and optimum irrigation without excess or deficiency is realized for the plant P to be cultivated.

  Further, the irrigation amount by the auxiliary irrigation device 15 can be appropriately adjusted by changing the set value s of the water level change detected by the float switch 14 and the depth t of the irrigation pipe 22 inserted into the soil 12. That is, the amount of irrigation from the auxiliary irrigation device 15 can be adjusted by changing the set value s, and the way in which the water from the irrigation pipe 22 spreads to the soil 12 can be adjusted by changing the depth t. The amount of surplus water recirculated to 13 can be varied. Thereby, it becomes possible to adjust the amount of irrigation according to the type of plant P to be cultivated, its growth stage, the amount of evapotranspiration, etc., and irrigation suitable for the yield and sugar content of the crop obtained from the plant P to be cultivated can be performed. . In addition, adjustment of this irrigation amount can also be adjusted by changing the length of the distance from the root of the plant P to grow about the insertion position to the soil 12 of the irrigation pipe | tube 22, for example.

  Further, the water supply amount per operation of the pump 21 of the auxiliary irrigation device 15 depends on the sensitivity of the float switch 14 and the water retention amount of the water retention region R, and the irrigation pipe inserted into the cross-sectional area of the water storage tank 13 and the soil 12. It is directly related to the depth t of 22. Based on this relationship, if the amount of water supply per pump 21 is reduced as much as possible, it is possible to supply water with an evapotranspiration amount close to real time for the plant P to be cultivated, and it can also be used as a device for measuring the evapotranspiration amount. .

  Here, irrigation control can be understood as soil-plant-atmosphere as one continuous system (Kramer, “Water Environment and Plants” 1986, pp. 195-198). Therefore, the water absorption flow rate flowing through this control system is an amount adapted to the environment where the continuum is placed. In general, the amount of evaporation from the soil surface is very small compared to the amount of transpiration of the plant, so that the amount of water absorption may be generally regarded as the amount of transpiration of the plant.

[Measurement of water absorption over time]
The amount of water absorbed in the plant cultivation apparatus of the present invention is considered to be a necessary amount of water that the plant adapts to changes in microclimate and optimally maintains itself because the soil water retention amount is kept substantially constant.

  In order to demonstrate that, in the plant cultivation container 1 of the present invention, when the tomato is cultivated as the plant P, the water absorption potential of the atmosphere, which is the measured water absorption amount and the negative pressure value seen from the atmosphere side at that time The time course of (physical model) was compared. The results are shown in the graph of FIG. In the graph, the measured absorption is mL / min, the value of the atmospheric water potential is −MPa on the vertical axis, and the measurement date is shown on the horizontal axis.

  In the measurement, the measured water absorption is a value calculated based on the number of changes in the water level exceeding the set value s detected by the float switch 14 within a certain time, and the atmospheric water potential is the temperature and relative humidity at that time. The values calculated from the above were adopted.

  From the results shown in FIG. 2, it can be seen that the increase / decrease pattern of the atmospheric water potential, which is a numerical value based on the theory, is in good agreement with the increase / decrease pattern of the measured water absorption.

  Thereby, according to this invention, the amount of evapotranspiration according to a crop kind, a growth stage, and a cultivation environment can be measured in real time, and optimal irrigation without excess and shortage and a time lag is realizable.

  As a result, irrigation management is forced to trial and error based on intuition and experience, as it is said to be “3 years of watering”, but it is freed from the labor and can reduce the amount of soil to less than half of the conventional amount. .

  Actually, if the amount of soil to be used is tomato cultivation as in this example, it was about 30 L in the past, but 4.5 to 5 L, and 1/6 or less, could be saved.

  In addition, compared to standard soil cultivation, the fertilization amount can be reduced to about 30% and the irrigation amount can be reduced to about 80%. For this reason, the translocation of carbohydrates to fruits is promoted under low nitrogen conditions, and high quality crops can be obtained.

[Measurement of water retention amount]
Furthermore, in order to demonstrate that when the water supply by the plant cultivation apparatus 1 of the present invention is performed, the water retention amount of the soil 12 is kept substantially constant, the solar radiation strength when spinach is cultivated as a plant P in a house.・ The change over time in temperature and soil moisture content and the cumulative water supply over time were measured. The results of changes over time in solar radiation intensity, temperature, and soil moisture content are shown in the graph of FIG. 3A, and the integrated water supply is shown in the graph of FIG.

  The soil moisture content is measured using a soil moisture meter (manufactured by Delta-t, SM200) by the so-called ADR method, and the solar radiation intensity is measured using a solar radiation meter (manufactured by Eihiro Seiki Co., Ltd., Ms-802). I went. Moreover, the numerical value of the integrated water supply amount was obtained by integrating the numerical values obtained based on the same calculation method as the water absorption amount in FIG.

  From the results of FIG. 3, it can be seen that the soil moisture content is maintained at a substantially constant value of 33 to 35% with respect to the solar radiation intensity and temperature that change from moment to moment.

  As mentioned above, although embodiment of this invention was described in detail, the plant cultivation apparatus and irrigation control method of this invention are not limited to the said embodiment, Even if all the technical thoughts considered within the range are included. Good.

1 Plant cultivation equipment 10 Plant cultivation container 11 Irrigation cloth (irrigation sheet)
12 Soil 13 Water storage tank (water storage container)
14 Float switch (water level sensor)
15 Auxiliary irrigation device 20 Irrigation tank 21 Pump 22 Irrigation pipe 25 Root permeation cloth P Growing plant R Water retention area s Float switch setting t Depth of irrigation pipe inserted into soil

Claims (7)

A plant cultivation container having an inclined bottom;
A irrigation sheet laid on the bottom of the container;
Soil that is housed and planted in the plant cultivation container; and
A water storage container that is provided on the inclined lower end side of the cultivation container, and the irrigation sheet is inserted to perform bottom irrigation on the soil via the capillary phenomenon of the irrigation sheet;
A water level sensor provided in the water storage container;
A plant cultivation device comprising: an auxiliary irrigation device that further irrigates the soil from above the plant cultivation vessel based on a decrease in the water level of the water storage vessel detected by the water level sensor.   The plant cultivation apparatus according to claim 1, wherein a root-permeable permeable sheet is laid on the irrigation sheet.   The plant cultivation device according to claim 1 or 2, wherein irrigation by the auxiliary irrigation device is performed through a irrigation tube, and a tip region of the irrigation tube is inserted near a root of the plant in which the soil is planted.   The plant cultivation device according to any one of claims 1 to 3, wherein the irrigation amount is adjusted by a set value of a water level change amount detected by the water level sensor and a depth of the soil into which the auxiliary irrigation device is inserted. An irrigation control method using the plant cultivation apparatus according to any one of claims 1 to 4,
(A) the irrigation sheet performs bottom irrigation;
(B) the water level sensor detecting a drop in the water level of the water storage container by this irrigation;
(C) based on the detected decrease in the water level of the reservoir, the auxiliary irrigation device further irrigates the soil to form a water retention area around the root of the plant in which the soil is planted;
(D) A method of controlling irrigation, comprising a step of surplus water that has not been used for forming the water retention region flows into the water storage container. (E) a step in which the water level sensor detects an increase in the water level of the water storage container by the inflow of the excess water;
The irrigation control method according to claim 5, further comprising: (f) the step of stopping the irrigation by the auxiliary irrigation device based on the detected rise in the water level of the water storage container.   The irrigation control method according to claim 6, wherein the irrigation of the auxiliary irrigation device is based on the fact that the water level sensor detects the rise of the water storage container to the initial water level.