JPH07275754A - Liquid manure spraying system - Google Patents

Abstract

PURPOSE:To maintain a specified nitrogen concn. regardless of the quantity of the nitrogen included in a water intake source by spraying a water mixture composed of water and liquid manure, detecting the electric conductivity of this water mixture, measuring the concn. of the liquid manure and controlling the supply rate of the liquid manure in such a manner that the measured value coincides with a reference value. CONSTITUTION:The water 9 in a water storage tank 3 is supplied to sprinklers of respective lots 5a, 5b through water feed pipes 6 and is sprayed when an arbitrary water spraying pump 10 is driven. A control section 22, thereupon, drives a liquid manure pump 15 and controls the opening degree of a control valve 14 to supply the liquid manure 29 of a liquid manure tank 16 to a mixer 12. Then, the water 9 and the liquid manure 29 are mixed by a mixer 12 to the water mixture for spraying which is made to flow out. At this time, the electric conductivity corresponding to the total quantity of the nitrogen in the water mixture for spraying is detected by an electric conductivity detector 20. The concn. of the nitrogen of the water mixture is measured in accordance with the detected electric conductivity and the opening degree of the control valve 14 is so controlled that the measured value coincides with the reference value in the control section 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fertilizer spraying system used in a golf course, a fruit garden, or the like which occupies a relatively large area.

[0002]

2. Description of the Related Art Conventionally, in a golf course or the like, a traveling vehicle equipped with a tank containing a chemical solution has been prepared in order to spray a chemical solution or liquid fertilizer on a vast land to grow a lawn. A method of spraying a chemical solution or the like while traveling all over the golf course was taken (for example, the actual Kaihei 5
-82894).

Recently, as an apparatus for spraying agricultural chemicals without using such a traveling vehicle, Japanese Patent Laid-Open No. 4-7 has been proposed.
The agricultural chemical spraying apparatus described in Japanese Patent No. 9830 is provided.

As shown in FIG. 11, this pesticide spraying device is provided with spraying parts 72, 72 ... Surrounding the green 71 at several places around the green 71 on a golf course. 72 ... are connected by a communication pipe 73, a water guiding part 74 is laid on the side of the green 71, and the water guiding part 74 and the spraying part 72 or the communication pipe 73 are connected by a water supply pipe 75. A pesticide mixing section 76 for mixing pesticides is provided in the water supply pipe in the middle of 75.

FIG. 12 shows a specific structure of the chemical liquid mixing section 76.

That is, an electromagnetic valve 81, a pulse transmission flow meter 82 and a stirring section 83 are provided in a water supply pipe 75 laid between the water guiding section 74 and the green 71, and the pulse transmission flow meter 82 and stirring are provided. To the water supply pipe 75 between the portion 83 and the portion 83 via the chemical liquid injection valve 84 and the chemical liquid injection pump 85.
6 are connected. Then, the pesticide mixture amount control unit 87
Sends a signal to the chemical liquid injection pump 85 based on the measurement result of the pulse transmission flow meter 82, and controls so that a desired amount of chemical liquid is injected into the water supply pipe 75 with respect to the constant amount of water passing through the electromagnetic valve 81. Is going.

[0007]

However, the above-mentioned spraying of agricultural chemicals by a traveling vehicle has the following various problems.

(1) When spraying on a traveling vehicle, every time the chemical solution in the chemical solution tank becomes empty, the chemical solution storage location is replenished, the chemical solution tank is filled up again, and then returned to the location where the chemical solution is being sprayed. Since the reciprocal traveling between the drug solution storage location and the spray location is repeated, such as spraying again, the spraying requires a long time and a lot of manpower. Especially at golf courses, etc., because the time zone that can be sprayed is limited,
It is not preferable that the application takes a long time.

(2) Although it can be sprayed on the places where the traveling vehicle has passed, it cannot be sprayed on the places where the traveling vehicle has not traveled. Therefore, depending on the way the traveling vehicle travels, there are left-over spraying, duplicate spraying, etc. Difficult to spread almost evenly.

(3) Since the spraying pressure varies depending on the remaining amount of the chemical liquid in the chemical liquid tank, it is difficult to spray the liquid evenly from this point.

(4) It is not preferable for the growth of the lawn because the traveling vehicle steps on the lawn.

(5) In a place with a steep slope such as a golf course,
It is difficult to adjust the spray amount, and especially in the case of a down slope, since all the chemical liquid in the chemical liquid tank is biased to the front side, it may not be possible to spray depending on the remaining amount of the chemical liquid.

(6) At golf courses and the like, it is difficult to frequently spray a thin chemical solution due to the time, and therefore, there is a tendency to spray a high-concentration chemical solution or liquid fertilizer to such an extent that the lawn does not die. If it rains immediately after spraying the concentrated chemical or fertilizer, the high-concentration chemical or fertilizer will flow to the downstream side,
It may pollute the surrounding area.

Further, the above-mentioned pesticide spraying device has the following problems.

That is, in the conventional pesticide spraying apparatus, the pesticide mixture amount control section 87 merely controls the injection amount of the chemical liquid with respect to the water amount from the water guiding section 74 so as to keep it at a constant rate. That is, when the amount of water increases, the injection amount of the chemical liquid increases, and when the amount of water decreases, the injection amount of the chemical liquid only decreases. Therefore, when this pesticide spraying device is applied to spray liquid fertilizer, the concentration of the liquid fertilizer in the water conveyance section 74 is reduced. When the liquid fertilizer is further injected at a high temperature, the concentration of the liquid fertilizer becomes too high and the lawn or the like grows rapidly, and in the case of a plant that is likely to hit the fertilizer, the liquid fertilizes. Further, even if insufficient liquid fertilizer is injected when the liquid fertilizer concentration in the water guiding section 74 is low, there is a problem that the liquid fertilizer concentration is low and the effect is small, and good growth of the lawn or the like cannot be achieved.

That is, when the water source used for spraying liquid fertilizer is a reservoir or river, liquid fertilizer contained in the water [particularly nitrogen, depending on the season and the amount of rainfall (during the rainy season, summer drought season, etc.). This is because the amount of (N)] varies greatly.

The present invention was devised to solve such problems, and its purpose is to spray liquid fertilizer having a constant nitrogen concentration regardless of the amount of nitrogen contained in the water intake source. It is to provide a liquid fertilizer application system capable of

[0018]

In order to solve the above problems, in the liquid fertilizer spraying system according to claim 1 of the present invention, a water storage tank and a water sprinkler installed at a predetermined place are connected by a water supply pipe, Applied to a system in which water stored in a water storage tank is sprinkled from the sprinkler via the water supply pipe, a liquid fertilizer tank for storing liquid fertilizer, and provided in the middle of the water supply pipe, and taken out from the liquid fertilizer tank. The liquid fertilizer contained in the mixed water is provided by mixing the liquid fertilizer with the water flowing in the water supply pipe and the water supply pipe on the downstream side of the mixer, and measuring the conductivity of the mixed water. Based on the liquid fertilizer concentration measuring unit for measuring the concentration of the liquid fertilizer concentration measuring unit, the liquid fertilizer from the liquid fertilizer tank to the mixer so that the concentration of the liquid fertilizer contained in the mixed water becomes a substantially constant value. Supply of A structure in which a Gosuru controller.

Further, in the liquid fertilizer spraying system according to a second aspect of the present invention, in the above structure, the controller controls the liquid fertilizer pump provided in the liquid fertilizer supply pipe connecting the liquid fertilizer tank and the mixer. Then, it is configured to control the amount of liquid fertilizer supplied from the liquid fertilizer tank to the mixer.

In the liquid fertilizer spraying system according to a third aspect of the present invention, in the configuration according to the first aspect, the controller is provided in the liquid fertilizer supply pipe connecting the liquid fertilizer tank and the mixer. The control valve is controlled to control the amount of liquid fertilizer supplied from the liquid fertilizer tank to the mixer.

In the liquid fertilizer application system according to a fourth aspect of the present invention, the control of the liquid fertilizer pump or the control valve by the control unit is performed by proportional integral control (PI), proportional derivative control (PD), or proportional integral derivative. It is configured to be performed by control (PID).

[0022]

The operation of the invention described in claim 1 will be described.

When the spraying is started, water is continuously supplied from the water storage tank to the sprinkler through the supply pipe. At this time,
The control unit controls to supply the liquid fertilizer stored in the liquid fertilizer tank to the mixer.

Therefore, on the downstream side of the mixer, the mixed water in which the liquid fertilizer and water are mixed is supplied to the sprinkler. Then, the conductivity of the mixed water is measured by the liquid fertilizer concentration measuring unit provided in the water supply pipe on the downstream side of the mixer, and the concentration of the liquid fertilizer contained in the mixed water is measured from this conductivity.
In the control unit, based on the measurement result of this liquid fertilizer concentration measuring unit,
The amount of liquid fertilizer supplied from the liquid fertilizer tank to the mixer is controlled so that the concentration of liquid fertilizer contained in the mixed water becomes a constant value.

By doing so, even if the amount of liquid fertilizer (specifically, nitrogen) contained in the water supplied from the water storage tank fluctuates, the liquid sprinkler always produces liquid fertilizer kept at a constant concentration. Will be sprayed.

The operation of the invention described in claim 2 will be described.

In the liquid fertilizer spraying system according to the first aspect, the controller controls a liquid fertilizer pump provided in a liquid fertilizer supply pipe connecting between the liquid fertilizer tank and the mixer so that the liquid fertilizer tank moves to the mixer. Control the amount of liquid fertilizer supplied. As such a liquid fertilizer pump, for example, a type that can adjust the supply amount of liquid fertilizer by changing the rotational speed of the pump by controlling the rotational speed by an inverter can be used.

The operation of the invention described in claim 3 will be described.

In the liquid fertilizer spraying system according to the first aspect, the control unit controls a control valve provided in a liquid fertilizer supply pipe connecting between the liquid fertilizer tank and the mixer so that the liquid fertilizer tank is connected to the mixer. Control the amount of liquid fertilizer supplied.

The operation of the invention described in claim 4 will be described.

If the liquid fertilizer (nitrogen) concentration measured by the liquid fertilizer concentration measuring unit is low at the start of the operation of this system, the control unit controls to supply a large amount of liquid fertilizer from the liquid fertilizer tank to the mixer. As a result, a large amount of liquid fertilizer is mixed with the water supplied from the water storage tank by the mixer, and the nitrogen concentration of the mixed water rapidly rises to reach the predetermined prescribed concentration. Then, the above-mentioned mixed water having a predetermined prescribed concentration will be measured by the liquid fertilizer concentration measuring unit, and therefore the control unit considers that the supply of liquid fertilizer is no longer necessary based on the measurement result, and this time There is a possibility that control such as a sudden decrease in the supply amount of In other words, the supply amount of liquid fertilizer is not stable forever, and large fluctuations may occur.

Therefore, in the actual control, in order to reduce the fluctuation range of the liquid fertilizer supply amount and quickly stabilize the liquid fertilizer at a substantially predetermined concentration, the liquid fertilizer pump or the control valve is controlled by proportional integral control (PI) or proportional derivative control (PI). PD) or proportional-integral-derivative control (PID).

As a result, the concentration of liquid fertilizer contained in the sprayed mixed water can be kept substantially constant within an extremely short time after the start of operation of this system.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show the outline of the overall construction of the liquid fertilizer application system of the present invention.

In the figure, water drawn from the well 1 and nearby rivers, ponds, swamps, etc. is temporarily stored in a reservoir 2 provided on the premises and then pumped to a water storage tank 3 as needed. It has become. In this way, the water pumped up from the well 1 or the like is temporarily stored in the reservoir 2 and then pumped up to the water storage tank 3 as needed, whereby the capacity of the water storage tank 3 can be reduced to some extent. In addition, at a golf course or the like, by providing a reservoir 2 or the like on the site, it becomes preferable from the viewpoint of scenery.

On the other hand, the water 9 stored in the water storage tank 3
A sprinkler for spraying, for example, a sprinkler 4
Is each construction section 5a, 5b that divides the site into a certain area
A plurality of them are arranged in the interior at regular intervals.

Then, from the water storage tank 3 to the construction sections 5a, 5
b are respectively connected by water supply pipes 6, 6 ..., And from each water supply pipe 6, 6 ... to each sprinkler 4, 4 ... in each work section 5a, 5b, branch pipe 8a, It is connected by 8b ...

Further, a water spray pump 10, a pressurizing tank 11, a mixer 12 and a control valve 30 are provided in each of the water supply pipes 6, 6 ...
.. are arranged in this order toward the side. Then, the water supply pipe 6 on the upstream side (the water storage tank 3 side) of the mixer 12
Liquid fertilizer supply pipe 1 whose one end is connected to liquid fertilizer tank 16
The other end of 7 is connected to the liquid fertilizer supply pipe 17,
A backflow prevention valve 13, a control valve 14, and a liquid fertilizer pump (quantitative pump) 15 are provided.

A conductivity detector 20 is provided on the water supply pipe 6b on the downstream side of the mixer 12 (on the side of the sprinkler 4), and the output of this conductivity detector 20 is transmitted via a conductivity transmitter 21. The control unit 22 that controls the supply amount of the liquid fertilizer 29
Have been led to.

The control output of the control unit 22 is led to the control valve 14 and the liquid fertilizer pump 15, and based on the conductivity detection value sent from the conductivity transmitter 21, the control valve 14 and / or Or liquid fertilizer pump 15
It is designed to control the opening and closing of.

The control unit 22 has a wireless transmission / reception unit (not shown), and is bidirectionally connected to the host computer 7 installed at the management place by a wireless line. The control unit 22 controls opening / closing of the control valve 14 and / or the liquid fertilizer pump 15 in accordance with the control signal from the host computer 7. However, when a manual / automatic changeover switch (not shown) is provided on the control unit 22 side and this changeover switch is changed over to the manual side, regardless of the control of the host computer 7,
It may be configured so that it can be controlled on site.

Reference numerals 25 and 26 in the figure denote compressors, which are compressors 2 connected to the pressure tank 11.
Reference numeral 5 is for supplying air into the pressure tank 11 to bring the pressure tank 11 into a pressurized state, and the compressor 26 connected to the control valve 14 operates an air cylinder (not shown). This is for opening and closing the control valve 14. However, the control valve 14 may be configured such that the electric valve is opened and closed by a servo motor. Further, the compressor 25 connected to the pressurizing tank 11 is not necessarily required because it is also in a pressurized state by the air contained in the water supply pipe 6, but it is not always necessary to obtain a sufficient and stable pressure. It is more preferable to provide.

In the above structure, the mixer 12 for mixing the water 9 from the water storage tank 3 and the liquid fertilizer (specifically, a nitrogen liquid) 29 from the liquid fertilizer tank 16 is, for example, a static mixer or a screw rotary type. A mixer, a rotary vane mixer, or the like can be used. In this embodiment, a static mixer is used. The static mixer is
As shown in FIG. 3, the rectangular plates are twisted by 180 degrees, and the elements 121 are arranged alternately at right angles. In this embodiment, four elements are arranged.

Liquid fertilizer 2 stored in the liquid fertilizer tank 16
9 is mainly nitrogen, but phosphorus (P) and potassium (K)
Such fertilizer may be mixed in an appropriate amount depending on the type of plant. Further, the liquid fertilizer 29 can reduce the capacity of the liquid fertilizer tank 16 by containing the undiluted liquid, but it may be diluted.

As the conductivity detector 20 for detecting the conductivity of the mixed water, both a direct insertion type conductivity detector and a flow type conductivity detector can be used. The direct insertion type conductivity detector can be used. Examples thereof include a screw-in type (see FIGS. 4 and 5) and a flange connection type (see FIG. 6). Further, as the flow-through type conductivity detector, for example, a flange coupling piping system for high range (see FIG. 7), a screw coupling piping system for low range and medium range (see FIG. 8), etc. is there. In FIG. 4, 2
Reference numeral 01 is a terminal box accommodating wiring terminals for connecting a dedicated cable (not shown), 202 is a wiring port, 203 is a lock nut, and 204 is an electrode. Further, in FIG. 7, 205
Is a connector for connecting a dedicated cable, 206 is a lock nut, 207 is an electrode, 208 is a mixed water inlet, 209
Is a mixed water outlet, and 210 is a fitting.

Further, the conductivity transmitter 21 converts the conductivity of the mixed water detected by the conductivity detector 20 into a current signal and transmits it to the controller 22.

The control unit 22 measures the nitrogen concentration contained in the mixed water based on the data transmitted from the conductivity transmitter 21, and the nitrogen concentration contained in the mixed water is measured based on the measurement result. Liquid fertilizer tank 16 so that it becomes a constant value
The amount of the liquid fertilizer 29 supplied from the mixer to the mixer 12 is controlled.

Here, the conductivity of the mixed water [electrical conductivity (μ
S / cm)] and the concentration of nitrogen contained in the mixed water (pp
Regarding the correlation with m), the present inventors have confirmed by experiments that the relationship is completely linear as shown in FIG. In Figure 9,
The measurement results for three types of liquid fertilizer are shown. The graph indicated by reference numeral 33 is the liquid fertilizer (a) of S company, the graph indicated by the reference numeral 34 is liquid fertilizer (b) of the S company, and the graph indicated by reference numeral 35 is 0.
The liquid fertilizer of the company. Although the inclination angle varies depending on the type of liquid fertilizer, they all have a linear relationship.

That is, the concentration of liquid fertilizer can be easily obtained by measuring the electric conductivity of the mixed water.

Therefore, in a memory (not shown) of the control unit 22, data indicating the correlation between the electric conductivity and the nitrogen concentration according to the type of the liquid fertilizer 29 stored in the liquid fertilizer tank 16 is stored in advance. To do.

Next, the operation of the liquid fertilizer application system having the above configuration will be described.

When any sprinkling pump 10 is driven and the corresponding control valve 30 is opened to start spraying, the water storage tank 3
Water is supplied to the sprinkler 4 through the water supply pipe 6 and is then sprayed.

At this time, the controller 22 controls the liquid fertilizer pump 15
Is controlled, the opening of the control valve 14 is controlled, and the liquid fertilizer 29 stored in the liquid fertilizer tank 16 is supplied to the mixer 12. However, the opening degree of the control valve 14 during operation is initially set to be a certain fixed opening degree.

As a result, the water 9 flowing from the water storage tank 3 through the water supply pipe 6 and the liquid fertilizer 29 supplied from the liquid fertilizer tank 16 are mixed in the mixer 12, and therefore, on the downstream side of the mixer 12. When flowing out to a certain water supply pipe 6b, it becomes a mixed water in which the water 9 and the liquid fertilizer 29 are almost evenly mixed (hereinafter, referred to as sprinkling mixed water).

Therefore, the water supply pipe 6 on the downstream side of the mixer 12
With the conductivity detector 20 provided in b, the conductivity of the sprinkling mixed water is accurately measured. The conductivity at this time is a value corresponding to the total amount of nitrogen obtained by summing the nitrogen originally contained in the water 9 in the water storage tank 3 and the nitrogen contained in the liquid fertilizer 29 supplied from the liquid fertilizer tank 16. Has become.

The value of the electric conductivity (electrical conductivity) measured by the electric conductivity detector 20 at any time is converted into a current signal in the electric conductivity transmitter 21 and then immediately transmitted to the control unit 22.

In the control unit 22, based on the measurement data sent from the conductivity transmitter 21, the correlation data between the electric conductivity and the nitrogen concentration stored in advance is included in the sprinkling mixed water. Calculate the nitrogen concentration. Then, a comparison is made with the reference nitrogen concentration set inside, and the opening degree of the control valve 14 is controlled so that the measured nitrogen concentration value matches the reference nitrogen concentration. Here, the reference nitrogen concentration is set to the most preferable value for plants. This value varies depending on the amount of water sprayed per unit area, the number of water sprays, etc., but in this embodiment, the amount of water sprayed was 3.42 (liter / m ² ).
In contrast, the T-N injection amount is set to 30 (ppm).

The control by the control unit 22 is basically performed as follows.

That is, when the measured nitrogen concentration value is lower than the reference nitrogen concentration value, it means that the nitrogen concentration of the sprinkling mixed water is too low. Therefore, the control unit 22 controls the control valve 14 at this time. Control in the opening direction.

On the other hand, if the measured nitrogen concentration value is higher than the reference nitrogen concentration value, it means that the nitrogen concentration of the sprinkling mixed water is too high. Therefore, at this time, the control unit 22 turns on the control valve 14. Control in the closing direction.

As a result, the amount of nitrogen contained in the water mixture for sprinkling and the water mixture for sprinkling is constantly controlled to a constant amount suitable for growing lawns.

Here, as control for matching the measured nitrogen concentration value with the reference nitrogen concentration value, proportional integral control (P
I), proportional derivative control (PD), proportional integral derivative control (PID), etc., but in the present embodiment, PID control is used.

That is, in order to obtain each PID constant, auto-tuning by the limit cycle method is performed. When performing auto-tuning, set the control output during operation to 100% (or the output limit upper limit setting value), and set the control output to 0% (or the output limit lower limit setting when the measured nitrogen concentration value ≥ the reference nitrogen concentration value). Value). After that, when the measured nitrogen concentration value <reference nitrogen concentration value, the control output is set to 100% again. Such control is repeated, for example, three times, and each constant of PID is determined from the change curve at that time.

In this embodiment, the proportional sensitivity (P) = 300%, the integration time (T) = 8 sec, and the differentiation time (D).
= 2 sec.

Since the PID control is a general one which has been conventionally performed, the description of the specific control operation is omitted here.

FIG. 10 shows another embodiment of the liquid fertilizer application system of the present invention. However, in the liquid fertilizer application system shown in the present embodiment, the same parts as those of the liquid fertilizer application system of the embodiment shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted here. Further, in FIG. 10, for simplification of the drawing, only the configuration of one system of the water supply pipe 6 and the liquid fertilizer supply pipe 17 for one construction area is shown.

That is, in this embodiment, the control valve 14 shown in FIG. 1 and the corresponding compressor 2
6 and 6 are omitted. Then, the rotation speed of the liquid fertilizer pump 41 is changed by the rotation speed control by the inverter,
The liquid fertilizer 29 is configured to adjust the injection amount. In addition to this, in the present embodiment, when the water is pumped from the reservoir 2 to the water storage tank 3, the water is temporarily stored in the water storage tank 43. As for the construction section 5c, in addition to water sprinkling by the sprinkler 4, water is sprinkled on the trees by providing an opening 44 on the ground, water is sprinkled in the ground, or a branch pipe is placed in the air. 8
Various spraying methods such as spraying water from c to a shower can be used. Although not shown, the control unit 22 is bidirectionally connected to the host computer by a wireless line.

Regarding the control of the liquid fertilizer pump 41,
Similar to the control of the control valve 1 described above, control by proportional integral control (PI), proportional derivative control (PD), proportional integral derivative control (PID), or the like is possible.

As described above, according to the liquid fertilizer application system of the present invention, compared with the application by the traveling vehicle shown in the prior art, it is possible to apply the liquid fertilizer to a vast area with less manpower, and the vehicle can be applied. It is preferable from the standpoint of growing plants, because it cannot be compacted by.

Further, when the liquid fertilizer application system of the present invention is applied to a golf course or the like, it can be applied not only in the morning and evening but also at night. Therefore, by frequently applying a thin liquid fertilizer, it is possible to grow plants healthy. Even if it rains immediately after spraying, the concentration of liquid fertilizer is low, so there is no concern that it will flow downstream and pollute the surrounding area. In particular, in a reservoir or the like provided at a golf course, it is possible to keep the nitrogen amount below a reference value (for example, 1 ppm) set by each prefecture.

[0072]

The liquid fertilizer spraying system of the present invention comprises a liquid fertilizer tank for storing liquid fertilizer and a mixer provided in the middle of the water supply pipe for mixing the liquid fertilizer taken out from the liquid fertilizer tank with the water flowing in the water supply pipe. A liquid fertilizer concentration measuring unit for measuring the concentration of liquid fertilizer contained in the mixed water by measuring the conductivity of the mixed water, which is provided in the water supply pipe on the downstream side of this mixer.
Based on the measurement result of the liquid fertilizer concentration measurement unit, so that the concentration of liquid fertilizer contained in the mixed water is a substantially constant value, a configuration including a control unit for controlling the amount of liquid fertilizer supplied from the liquid fertilizer tank to the mixer Therefore, regardless of the amount of nitrogen contained in the water intake source, liquid fertilizer can be sprayed with the total nitrogen amount always kept at a constant concentration.

The liquid fertilizer pump or the control valve is controlled by proportional integral control (PI) or proportional derivative control (P).
D) or the proportional-integral-derivative control (PID) configuration makes it possible to keep the concentration of liquid fertilizer contained in the sprayed mixed water almost constant in an extremely short time after the start of operation of this system. Becomes

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a liquid fertilizer application system of the present invention.

FIG. 2 is an enlarged view showing each work section portion shown in FIG.

FIG. 3 is a diagram showing a shape of an element forming a static mixer.

FIG. 4 is a view showing an example of a screw-in type direct insertion type conductivity detector.

FIG. 5 is a diagram showing an example of a screw-in type direct insertion type conductivity detector.

FIG. 6 is a view showing an example of a flange connection type direct insertion type conductivity detector.

FIG. 7 is a diagram showing an example of a flow coupling type conductivity detector of a flange coupling piping system for a high range.

FIG. 8 is a diagram showing an example of a flange-coupled piping type flow-through conductivity detector for the low range and the medium range.

FIG. 9 is a graph showing the correlation between the conductivity of mixed water and the concentration of nitrogen contained in the mixed water.

FIG. 10 is a view showing another embodiment of the liquid fertilizer application system of the present invention.

FIG. 11 is a piping diagram of a golf course to which a conventional pesticide spraying device is applied.

FIG. 12 is a block diagram showing an electrical configuration of a conventional pesticide spraying device.

[Explanation of symbols]

 3 Water Storage Tank 4 Sprinkler 6 Water Supply Pipe 12 Mixer 14 Control Valve 15,41 Liquid Manure Pump 16 Liquid Manure Tank 20 Conductivity Detector 21 Conductivity Transmitter 22 Controller 29 Liquid Manure 30 Control Valve

Claims (4)

[Claims] 1. A system in which a water storage tank installed at a predetermined place and a sprinkler are connected by a water supply pipe, and water stored in the water storage tank is sprinkled from the water sprinkler via the water supply pipe. A liquid fertilizer tank for storing liquid fertilizer, a mixer provided in the middle of the water supply pipe, for mixing the liquid fertilizer taken out from the liquid fertilizer tank with water flowing in the water supply pipe, and a water supply downstream of the mixer A liquid fertilizer concentration measuring unit that is provided in a pipe to measure the concentration of liquid fertilizer contained in the mixed water by measuring the conductivity of the mixed water, and based on the measurement result of the liquid fertilizer concentration measuring unit, contained in the mixed water. A liquid fertilizer spraying system, comprising: a control unit that controls the amount of liquid fertilizer supplied from the liquid fertilizer tank to the mixer so that the concentration of the liquid fertilizer to be supplied is substantially constant. 2. The liquid fertilizer is supplied from the liquid fertilizer tank to the mixer by controlling a liquid fertilizer pump provided in a liquid fertilizer supply pipe connecting between the liquid fertilizer tank and the mixer. The liquid fertilizer application system according to claim 1, which controls the amount. 3. The liquid fertilizer is supplied from the liquid fertilizer tank to the mixer by controlling a control valve provided in a liquid fertilizer supply pipe connecting the liquid fertilizer tank and the mixer. The liquid fertilizer application system according to claim 1, which controls the amount. 4. The control of the liquid fertilizer pump or the control of the control valve by the control unit is proportional integral control (P
I), proportional derivative control (PD), or proportional integral derivative control (PID), The liquid fertilizer application system of Claim 2 or 3.