JP5999595B2 - Irrigation control device and irrigation control method - Google Patents

Description

  The present invention relates to a water control apparatus and a water control method.

In fruit tree cultivation, the moisture state of the tree from the fruit enlargement stage to the fruit maturation stage greatly affects the fruit quality. In particular, it is known that in Citrus unshiu cultivation, it is possible to produce high-quality fruits with high sugar content by appropriately managing the moisture state of the trees in summer and autumn.
The most effective method for managing the moisture status of the tree body is management by irrigation control, but in actual fruit tree production sites, irrigation control largely depends on the experience and intuition of each producer, and is inappropriate. In some cases, sufficient quality fruit may not be produced by water control.
From the production site, there is a strong demand for a rational method capable of appropriately performing watering control in order to manage the moisture state of the tree.

The following are known as indexes of conventional irrigation control.
(1) The soil moisture condition (moisture content or pF value) is used as an index (see Patent Documents 1 to 4 and 8).
(2) Using the amount of solar radiation as an index (see Patent Documents 5 and 6).
(3) Using evapotranspiration as an index (see Patent Document 7).

JP 2008-125432 A JP 2002-65086 A JP 2002-315456 A JP 2001-157522 A Japanese Patent Laid-Open No. 11-289891 JP 2011-92152 A JP 2006-345768 A JP 2002-281842 A

  Among conventional irrigation controls, the control (Patent Documents 1 to 4 and 8), which uses the soil moisture state as an index, measures soil moisture, for example, for fruit trees in a wide and deep orchard. It is impossible to match the position to be rooted with the root zone, and it is difficult to appropriately reflect the moisture state of the tree body. The control using the soil moisture state as an index is suitable for tree planting and gardening, and is not suitable for perennial crops in the orchard.

  Further, the control (Patent Documents 5 and 6) using the amount of solar radiation as an index does not directly reflect the moisture state of the tree. Furthermore, the control using the amount of evapotranspiration (Patent Document 7) is not intended to appropriately maintain the moisture state of the tree.

  All conventional irrigation controls have been used with indicators such as the amount of deficient water derived from the moisture balance of the tree and the degree of wetness of soil moisture. This is to perform sufficient watering to prevent excessive drying, and does not properly maintain the moisture state of the tree. It is difficult to say that these indirect indicators appropriately represent the moisture state of the tree.

  In the field of research, vigorous research has been conducted in consideration of biological information such as the moisture state of the tree. Generally, the water potential (moisture retention capacity) of a plant body is used as an index that directly represents the moisture state of the tree body. There are some cases where water potential is used to clarify the most suitable value of the moisture state of a tree. However, no examples have been found to bring the moisture state of the tree close to or maintain this optimum value, and no specific method has been proposed. Hereinafter, the water potential here indicates the value of the maximum water potential measured before sunrise.

  This invention is made | formed in view of such a conventional subject, and provides the irrigation control apparatus and the irrigation control method which can perform the irrigation control which maintains the moisture state of a plant appropriately, and can perform it. Objective.

  As a result of intensive studies, the present inventors have adopted the following water control apparatus and water control method in order to solve the above problems.

The brine control device of the present invention is
For a water irrigation device that irrigates a plant cultivated in an environment that is not easily affected by the weather, a preset target value of the water potential of the plant, an upper and lower allowable range centered on the target value, and a water potential A irrigation control device for controlling the irrigation device using a measured value of the water potential of the plant obtained from the measurement device,
A prediction line creating means for creating a prediction line from a plurality of the measured values;
A predicted value calculating means for calculating a predicted value from the predicted line;
In the case where the predicted value is within the allowable range, irrigation maintaining means for controlling to maintain the irrigation apparatus as it is,
And a irrigation adjusting means for controlling the irrigation device so that the predicted value falls within the allowable range when the predicted value is out of the allowable range.

  Here, when the predicted value is higher than the upper limit of the allowable range, the irrigation adjusting means preferably controls the irrigation apparatus so that the predicted value falls within the allowable range by reducing the irrigation amount.

  Moreover, when the predicted value is lower than the lower limit of the allowable range, the irrigation adjusting means preferably controls the irrigation apparatus so that the predicted value falls within the allowable range by increasing the irrigation amount. In addition, when the irrigation amount is increased, the irrigation adjustment means controls the irrigation device so that the amount of irrigation reaching the root area of the plant is the upper limit of the amount of irrigation performed at one time and the number of times of irrigation is performed multiple times. It is preferable. In this case, the total amount of irrigation carried out per day exceeds the upper limit of the amount of irrigation carried out at one time.

Moreover, the water control method of the present invention includes:
A irrigation control method for controlling irrigation using measured values of water potential of plants cultivated in an environment that is not easily affected by the weather,
Set a target value of the water potential of the plant and an upper and lower allowable range centered on this target value,
Create a prediction line from a plurality of the measured values, calculate the subsequent prediction value from this prediction line,
When the predicted value is within the allowable range, control is performed so as to maintain the brine.
When the predicted value is out of the allowable range, irrigation is controlled so that the predicted value falls within the allowable range.

  Here, when the predicted value is higher than the upper limit of the allowable range, it is preferable to control the irrigation so that the amount of irrigation is reduced and the predicted value falls within the allowable range.

  In addition, when the predicted value is lower than the lower limit of the allowable range, it is preferable to control the irrigation so that the predicted amount falls within the allowable range by increasing the irrigation amount. When increasing the irrigation amount, it is preferable to perform irrigation a plurality of times as the upper limit of the irrigation amount at which the amount of irrigation reaching the root area of the plant is performed once.

  In the irrigation control apparatus and the irrigation control method of the present invention, the predicted value of the water potential of the plant is calculated using the prediction line, and the irrigation is controlled so that the predicted value falls within the upper and lower allowable ranges centered on the target value. I did it. This makes it possible to bring the water potential closer to the target value. Therefore, it is possible to control the irrigation while appropriately maintaining the moisture state of the plant.

It is a figure which shows the irrigation management system of one embodiment of this invention. It is a flowchart which shows the irrigation control process of the embodiment. It is a graph which shows the example of the measured value and predicted value of the water potential of the embodiment. It is a graph which shows the example at the time of performing the measured value of the water potential and irrigation control processing of the embodiment. It is a graph which shows the example of the measured value and predicted value of the water potential following FIG. It is a graph which shows the fluctuation | variation of the water potential by the irrigation control processing of the embodiment, and the fluctuation | variation of the water potential by the conventional irrigation control processing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a brine management system 1 according to an embodiment of the present invention. The brine management system 1 according to the present embodiment performs precise brine management for fruit trees 6 (plants) and the like. As a method of irrigation, it is appropriate to use drip irrigation from among hand irrigation and sprinkler irrigation. Drip irrigation keeps irrigation with a small amount of water from each of a plurality of holes provided in the tube, and high irrigation efficiency is obtained. Moreover, there exists an advantage that it is easy to automate watering by using a solenoid valve etc.

  In this embodiment, it functions effectively when cultivated in an environment that is not easily affected by the weather. Examples of methods for cultivating fruit trees in an environment that is not easily affected by the weather include a method of cultivating fruit trees by covering the soil with a multi-sheet, a method of cultivating fruit trees in a house, and the like. The irrigation management system 1 of this Embodiment is used in the period which needs to control the water | moisture content of the tree body 6 by irrigation actively throughout a cultivation period. That is, for the purpose of improving fruit quality, the season used mainly by the brine management system 1 is the summer / autumn period.

  The irrigation management system 1 of the present embodiment includes a water potential measurement device 2, a irrigation control device 3 connected to the water potential measurement device 2, a irrigation device 4 connected to the irrigation control device 3, and a irrigation device 4. A connected water source 5 (a water supply device, a water supply tank, etc.) is provided. In FIG. 1, solid arrows indicate the flow of information such as control signals, and dotted arrows indicate the flow of water.

  The water potential measuring device 2 measures the water potential of the tree body 6 (water potential of leaves). There are several methods for measuring the water potential, such as the cyclometer method and the pressure chamber method. When considering the time required for the measurement and the time required for pretreatment, the water potential of a healthy leaf can be determined using the pressure chamber method. It is reasonable to select The water potential measuring device 2 is not limited to the pressure chamber method as in the present embodiment.

  The water potential used as an index is preferably before sunrise. The reason for this is that the leaves in any position on the tree body 6 are supposed to be homogeneous in moisture state before sunrise, so there is no variation depending on the position of the leaves, and it is possible to obtain a stable measurement value of the water potential. It is. The water potential measured before sunrise accurately represents the water state of the tree body 6. The smaller the value of the water potential, the stronger the dry state of the tree body 6 (water stress state). In fruit trees that are cultivated without sufficient watering, the water potential of the tree 6 gradually decreases.

  The irrigation device 4 irrigates the tree body 6. The irrigation apparatus 4 includes a plurality of electromagnetic valves 41 connected to the irrigation control apparatus 3 and a plurality of water spray pipes 42 (infusion tubes) connected to each electromagnetic valve 41. Water for irrigation is sent to the tree body 6 from the water source 5 through each electromagnetic valve 41 and the water spray pipe 42.

  In order to efficiently manage the moisture state of the tree 6, it is necessary to give the tree 6 sufficient moisture. Needless to say, the tree body 6 absorbs moisture mainly from the root region. Therefore, irrigation needs to supply sufficient water to the root area to be considered. The basic behavior of water immersed in soil by drip irrigation is settling and diffusion. Water that has flowed out of the root zone due to sedimentation or diffusion is not supplied to the tree body 6 and becomes wasted water. In order to prevent waste, the amount of water that reaches the root area of the tree body 6 is preferably set as the upper limit of the amount of water that is carried out at one time.

  The irrigation control device 3 controls the irrigation device 4 using the measured value of the water potential obtained by the water potential measurement device 2. This irrigation control device 3 controls the amount of irrigation, the number of times of irrigation, and the irrigation time by controlling the opening and closing of each electromagnetic valve 41 by connecting to each electromagnetic valve 41 of the irrigation device 4. Moreover, this irrigation control apparatus 3 is provided with each means (prediction line creation means, predicted value calculation means, irrigation maintenance means, irrigation adjustment means) of the present invention.

  In the irrigation management system 1 configured as described above, the procedure of the irrigation control process using the irrigation control device 3 will be described with reference to the flowchart of FIG. 2 and the graph of FIG. FIG. 3 shows five situations.

(Step S1)
First, the operator sets a target value X (see FIG. 3) of the water potential, and inputs this target value X to the irrigation control device 3. This target value X is a target value for manipulating the moisture state of the tree 6 artificially. If the target value is different, as a result of the watering control, the moisture state of the tree body 6 is also different, resulting in fruits with different qualities.

(Step S2)
Next, the operator sets an upper and lower allowable range ± α (see FIG. 3) around the target value X, and inputs this allowable range ± α to the irrigation control device 3. This allowable range ± α is an allowable error range with respect to the target value X, and α is set to a small value when strict control of the moisture state is intended. Conversely, in rough control, α is a large value.

(Step S3)
Next, the worker measures the water potential of the tree body 6 a plurality of times (in days), and inputs the obtained plurality of measured values to the irrigation control device 3. In this Embodiment, as shown to a1 to a6 of FIG. 3, the water potential is measured twice (elapsed days b1, b2). Here, the water potential at the time of the first measurement (elapsed days b1) is set as the initial value a1.

(Step S4)
The irrigation control device 3 uses a plurality of measured values a2 to a6 including a target value X of the water potential, an upper and lower allowable range ± α centered on the target value X, and an initial value a1 (see FIG. 3). Browse). The prediction lines L1 to L5 are examples in each situation. Since the water potential reflects the moisture state of the tree 6, it is a value that decreases monotonously if there is no rainfall or irrigation. Therefore, the prediction line for water potential is usually a decreasing line with a negative slope. Note that the prediction line L1 is an increasing line with a positive slope. This is because, for example, the influence of the weather due to rain is taken into account.

(Step S5)
Next, the irrigation control device 3 calculates predicted values a7 to a11 of the water potential thereafter (elapsed days b3) from the prediction lines L1 to L5. The predicted values a7 to a11 are values when the control is not changed in each situation.

(Step S6)
Next, the irrigation control device 3 determines whether the predicted values a7 to a11 are within the allowable range ± α.

(Step S7 → Step S9)
The irrigation control device 3 determines that the predicted value a9 is within the allowable range ± α (YES in step S6), and controls the irrigation device 4 to maintain the irrigation amount. The irrigation device 4 performs the first irrigation based on this control content. This watering time is the day when the predicted value a9 is determined to be within the allowable range ± α (elapsed days b2).

  The reason for maintaining the irrigation amount is to keep the predicted value at the elapsed days b3 within the allowable range ± α. Specifically, the irrigation amount is set as usual so that the inclination of the prediction line L3 is maintained (so that the prediction line L3 becomes L8 as a result of the irrigation control process of FIG. 4). As a result, as shown in FIG. 4, after the measurement value a4 is measured, the measurement value a14 measured by the elapsed days b3 is maintained within the allowable range ± α. Here, the normal irrigation amount is the amount of irrigation reaching the root zone.

(Step S8 → Step S9)
The irrigation control device 3 determines that the predicted values a7, a8, a10, and a11 are outside the allowable range ± α (NO in step S6), and controls the irrigation device 4 to adjust the irrigation amount. The irrigation device 4 performs the first irrigation based on this control content. This watering time is the day when the predicted values a7, a8, a10, a11 are determined to be outside the allowable range ± α (elapsed days b2).

  The reason for adjusting the irrigation amount is to put the predicted value at the elapsed days b3 within the allowable range ± α or close to the allowable range ± α.

  In the case of the prediction value a7, the inclination of the prediction line L1 is lowered so that the prediction line L1 becomes L6 in FIG. In the case of the prediction value a8, the inclination of the prediction line L2 is lowered so that the prediction line L2 becomes L7 in FIG. In order to lower the slopes of the prediction lines L1 and L2, the amount of irrigation is reduced more than usual. In addition, the normal watering amount is the amount of watering to reach the root zone as described above.

  As a result, as shown in FIG. 4, after the measurement value a2 is measured, the measurement value a12 measured with the elapsed days b3 approaches the upper limit + of the allowable range ± α, and after the measurement value a3 is measured, the measurement is performed with the elapsed days b3. The value a13 falls within the allowable range ± α.

  When the predicted value is higher than the upper limit + α of the allowable range ± α and the slope is positive as in L1, that is, when the predicted line moves away from the upper limit + α, the amount by which the irrigation amount decreases as the slope increases. When the slope is negative as in L2, that is, when the prediction line approaches the upper limit + α, the amount of water reduction is increased as the slope is smaller.

  In the case of the prediction value a10, the inclination of the prediction line L4 is increased so that the prediction line L4 becomes L9 in FIG. In the case of the predicted value a11, the inclination is increased so that the predicted line L5 becomes L10 in FIG. In order to increase the slopes of the prediction lines L4 and L5, the watering amount is increased more than usual. Specifically, irrigation is carried out several times as the upper limit of the irrigation amount that reaches the root zone at one time, and the total irrigation amount to be carried out on one day is increased.

  As a result, as shown in FIG. 4, after the measurement value a5 is measured, the measurement value a15 measured by the elapsed days b3 is maintained within the allowable range ± α, and after the measurement value a6 is measured, the measurement values measured by the elapsed days b3. a16 approaches the lower limit −α of the allowable range ± α.

  In the prediction line where the predicted value is lower than the lower limit −α of the allowable range ± α, when the slope is negative as in L4 or L5, that is, when the predicted line moves away from the lower limit −α, the irrigation amount increases as the slope increases. Increase the amount of increase. Although not shown, when the slope is positive, that is, when the prediction line approaches the lower limit −α, the amount of watering to be increased is increased as the slope is smaller.

  In this way, in the first irrigation, the irrigation amount is controlled based on the prediction value, the magnitude of the inclination of the prediction line, and the normal irrigation amount so that the prediction value falls within the allowable range ± α.

The contents of the first watering control are summarized below.
(1) Predicted value is within an allowable range ± α.
(2) The predicted value is higher than the allowable range ± α upper limit + α.
The slope of the prediction line is positive ... The greater the slope, the greater the amount of water reduction.
The slope of the prediction line is negative… The smaller the slope, the greater the amount of water reduction.
(3) The predicted value is lower than the lower limit −α of the allowable range ± α. (Implement water multiple times as the upper limit of the amount of irrigation that reaches the root zone at one time, and increase the total amount of irrigation per day.)
The slope of the prediction line is positive ... The smaller the slope, the greater the amount of watering.
The slope of the prediction line is negative ... The greater the slope, the greater the amount of watering.

(Step S10)
When the first irrigation is completed, the operator determines whether or not the irrigation control device 3 should continue the irrigation control process depending on whether or not the moisture of the tree body 6 needs to be actively controlled by the irrigation. If irrigation is necessary, the process of steps S4 to S10 is repeated to bring the predicted value closer to the allowable range ± α, or the irrigation control process is performed so as to be within the allowable range ± α. This will be described with reference to FIG.

(Step S4)
The irrigation control device 3 creates prediction lines L11 to L15 using the measured values a2 to a6 before the first irrigation (elapsed days b2) and the measured values a12 to 16 after the first irrigation (elapsed days b3). .

(Step S5 → Step S6)
The irrigation control device 3 calculates the predicted values a17 to a21 for the following (elapsed days b4) from the predicted lines L11 to L15, and determines whether these predicted values a17 to a21 are within the allowable range ± α. .

(Step S7 → Step S9)
The irrigation control device 3 determines that the predicted values a17 to a19 are within the allowable range ± α (YES in step S6), and maintains the irrigation amount for the irrigation device 4 on the determined date (elapsed days b3). Control to do. The irrigation apparatus 4 receives this control and performs the second irrigation on the determined day.

  In the case of the predicted value a17, in order to maintain the slope of the predicted line L11, the same amount as the initial watering amount (elapsed days b2) is set. In the case of the predicted value a18, in order to maintain the inclination of the predicted line L12, the amount is the same as the initial watering. In the case of the predicted value a19, in order to maintain the inclination of the predicted line L15, the amount is the same as the first watering. As a result, although not shown, after the measurement values a12, a13, and a16 are measured, the measurement value measured at the elapsed days b4 is maintained within the allowable range ± α.

(Step S8 → Step S9)
The irrigation control device 3 determines that the predicted values a20 and a21 are lower than the lower limit −α of the allowable range ± α (NO in step S6), and on the determined date (elapsed days b3) with respect to the irrigation device 4 Control to adjust the amount of irrigation. The irrigation apparatus 4 receives this control and performs the second irrigation on the determined day.

  In the case of the predicted value a20, the inclination of the predicted line L13 is increased so that the predicted value a20 falls within the allowable range ± α. In the case of the predicted value a21, the inclination of the predicted line L14 is increased so that the predicted value a21 falls within the allowable range ± α. That is, the number of times of watering in the second time is increased from the previous time. As a result, although not shown, the measurement values measured after measurement of the measurement values a14 and a15 (at the time point of elapsed days b4) fall within the allowable range ± α.

  Thus, in the second and subsequent irrigation, the irrigation amount is controlled based on the prediction value, the magnitude of the inclination of the prediction line, and the previous irrigation amount so that the prediction value falls within the allowable range ± α.

The contents of control of the second and subsequent irrigation will be described below.
(1) Prediction value is within the tolerance range ± α.
(2) The predicted value is higher than the upper limit + α of the allowable range ± α.
When the slope of the prediction line is positive: the greater the slope, the greater the amount of water reduction.
When the slope of the prediction line is negative: The amount of water reduction is increased as the slope is smaller.
(3) The predicted value is lower than the lower limit −α of the allowable range ± α. (Implement water multiple times as the upper limit of the amount of irrigation that reaches the root zone at one time, and increase the total amount of irrigation per day.)
When the slope of the prediction line is positive: Increase the amount of irrigation as the slope is smaller.
When the slope of the prediction line is negative: The greater the slope, the greater the amount of irrigation.

  Further, when the first or second irrigation is performed, if the entire prediction line is within the allowable range ± α, the measured value can be maintained within the allowable range ± α by maintaining the current irrigation. In addition, it is not necessary to measure the water potential during the period when the predicted value is within the allowable range ± α.

  When irrigation is repeatedly performed as described above, and the operator determines that it is not necessary to actively control the moisture of the tree body 6 by irrigation throughout the cultivation period (NO in step S10), the irrigation control process is performed. finish.

  As described above, in the irrigation control device 3 and the irrigation control method of the present embodiment, the predicted values are calculated using the prediction lines L1 to L5 and L11 to L15, and the predicted values fall within the allowable range ± α. So that irrigation was controlled. In other words, in the irrigation control device 3 and the irrigation control method of the present embodiment, the amount of irrigation is increased or decreased when it is predicted that the irrigation is outside the allowable range ± α. Thereby, as shown in FIG. 6, the fluctuation A of the water potential by the irrigation control process of the present embodiment is smaller than the fluctuation B of the water potential by the conventional irrigation control process, and the water potential approaches the target value X. be able to. Therefore, it is possible to control the irrigation while appropriately maintaining the moisture state of the tree body 6.

  For this reason, the irrigation control device 3 and the irrigation control method of the present embodiment may be applicable to citrus varieties such as Citrus unshiu, grapes, loquat, etc., which can be used for tree species that can reduce high-quality fruit production and obstacles by irrigation management. Is expensive.

  The increase in water potential is due to irrigation. In conventional irrigation treatment, excessive irrigation is performed in order to suppress a decrease in water potential. Therefore, as shown in the fluctuation B, the water potential is rapidly increased. On the other hand, in the irrigation control processing of the present embodiment, since the frequency of irrigation is increased by reducing the amount of irrigation at one time, as apparent from comparing the number of irrigation adjustment positions D, the fluctuation A is increased. As shown, the rise in water potential is slow.

  Moreover, since the irrigation adjustment process is performed by increasing or decreasing the irrigation amount, the water potential of the tree 6 can be easily brought close to the target value X. Therefore, the control process which maintains the moisture state of the tree 6 appropriately can be easily performed.

  In addition, when adjusting to increase the amount of irrigation, the upper limit of the amount of irrigation at one time is the amount of irrigation that reaches the root area of the tree. Can be suppressed.

  As mentioned above, although embodiment concerning this invention was illustrated, this embodiment does not limit the content of this invention. Various modifications can be made without departing from the scope of the claims of the present invention.

  For example, in the present embodiment, the operator sets the target value X and the allowable range ± α, but the irrigation control device may set it automatically.

  Further, in the present embodiment, the example in which the present invention is applied when watering the fruit tree 6 is described, but the scope of the present invention may not be limited to the watering of the fruit tree 6. The present invention may be applied when watering other plants.

  In the present embodiment, the water state of the tree body 6 is predicted using the water potential, but the water state of the tree body may be predicted using biological information other than the water potential.

  As described above, the irrigation control device and the irrigation control method of the present invention can control the irrigation while appropriately maintaining the moisture state of the plant. Therefore, the irrigation control device and the irrigation control method of the present invention can be fully utilized in the technical field of plant irrigation control.

1 Irrigation Management System 2 Water Potential Measurement Device 3 Irrigation Control Device 4 Irrigation Device 5 Water Source 6 Tree (Plant)
a1 to a6, a12 to a16 Measured values of water potential a7 to a11, a17 to a21 Predicted value of water potential X Target value of water potential ± α Upper and lower allowable range centered on target value + α Upper limit of allowable range -α Allowable Lower limit of range D Irrigation adjustment position L1-L5, L11-L15 Prediction line

Claims (8)

For a water irrigation device that irrigates a plant cultivated in an environment that is not easily affected by the weather, a preset target value of the water potential of the plant, an upper and lower allowable range centered on the target value, and a water potential A irrigation control device for controlling the irrigation device using a measured value of the water potential of the plant obtained from the measurement device,
A prediction line creating means for creating a prediction line from a plurality of the measured values;
A predicted value calculating means for calculating a predicted value from the predicted line;
When the predicted value is within the allowable range, irrigation maintaining means for controlling to maintain the irrigation state by the irrigation device;
In the case where the predicted value is out of the allowable range, the irrigation adjustment is performed to increase / decrease the amount of irrigation by the irrigation device so that the predicted value falls within the allowable range , or to control the frequency of irrigation by the irrigation device. Means,
An irrigation control device comprising: The irrigation control device according to claim 1,
When the predicted value is higher than the upper limit of the allowable range, the irrigation adjusting means controls the irrigation device so as to reduce the irrigation amount so that the predicted value falls within the allowable range. Brine control device. The irrigation control device according to claim 1,
When the predicted value is lower than the lower limit of the allowable range, the irrigation adjusting means controls the irrigation device so as to increase the irrigation amount so that the predicted value falls within the allowable range. Brine control device. The irrigation control device according to claim 3,
The irrigation adjusting means, when increasing the irrigation amount, sets the irrigation device to be the upper limit of the irrigation amount to be carried out at one time, reaching the root area of the plant at one time, A irrigation control device characterized by controlling. A irrigation control method for controlling irrigation using measured values of water potential of plants cultivated in an environment that is not easily affected by the weather,
Set a target value of the water potential of the plant and an upper and lower allowable range centered on this target value,
Create a prediction line from a plurality of the measured values, calculate the subsequent prediction value from this prediction line,
When the predicted value is within the allowable range, control to maintain the watering state of the plant ,
When the predicted value is out of the allowable range, the irrigation amount is controlled to increase or decrease so that the predicted value falls within the allowable range , or the irrigation frequency by the irrigation device is controlled. Control method. In the irrigation control method of Claim 5,
When the predicted value is higher than the upper limit of the allowable range, the irrigation control method is characterized in that the irrigation amount is reduced and the irrigation is controlled so that the predicted value falls within the allowable range. In the irrigation control method of Claim 5,
When the predicted value is lower than the lower limit of the allowable range, the irrigation control method is characterized in that the irrigation amount is controlled so that the predicted value falls within the allowable range. In the irrigation control method of Claim 7,
When increasing the amount of irrigation, the irrigation control method is characterized in that irrigation is performed a plurality of times as an upper limit of the amount of irrigation that reaches the root area of the plant at one time.