JPH09308396A - Negative pressure difference irrigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject compact and inexpensive irrigation system. SOLUTION: This irrigation system has such scheme that, in a container holding a soil bed 2 on the upper part and a water reservoir 3 thereunder, water-permeable porous pipes 4 are embedded in the soil bed, water from the reservoir 3 is saturated under negative pressured inside the pipes 4, and water in the pipes 4 is leached, through capillary mechanism, into the soil bed 2 owing to the negative pressure difference between the soil water in contact with the pipes 4 and the inside of the pipes 4. In this case, the flow channel connecting the pipes 4 and the water reservoir 3 to each other or branched pipe(s) from the flow channel is provided with a stretch/contractile portion variable in volume, and such a means 6 is provided so as to have such scheme that the portion is subjected to pressure application/release to extrude the gas generated in the flow channel together with water in this channel followed by suction of water into the channel to remove liberated air in the flow channel.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a negative pressure differential irrigation system.

[0002]

2. Description of the Related Art As one of water-saving irrigation methods for efficiently using water, there is a negative pressure differential irrigation method. This method is
In 34, BE Livingsto (BELivingsto
It was first introduced by n). The principle is that water is saturated in a porous pipe buried in the soil, and the water pressure in this pipe is set as a negative pressure, and irrigation is performed by the difference between the negative pressure in the soil in contact with the porous pipe and the negative pressure in the pipe. Therefore, it can be said that this method is suitable for controlling soil moisture.

This method is certainly excellent as a water-saving irrigation method, but when it is actually applied, the dissolved gas contained in the water in the water-permeable porous pipe and the pipe is bubbled due to the temperature change. Therefore, it has a major drawback that the negative pressure difference state is not maintained and the water supply is interrupted due to the reason that it stays in the pipe and blocks the pores, etc., which has been an obstacle to its widespread use. In 1988, Tanikawa et al. (Literature: Torahiko Tanikawa, Katsuhiko Yabe, Koji Tejima, Proceedings of the Japan Society of Agricultural Engineering 13
7 , pp17-23 (1988), Setting method of negative pressure in soil pipes and measures for eliminating bubbles-Experimental study on underground irrigation (V
In order to solve the above problems, I)) has proposed a device that eliminates air bubbles by connecting the vinyl hose to the joint part of the water-permeable porous pipe and applying the siphon principle. It is necessary to raise and lower the level, and there is a difficulty in operation for easy use. There is also a method of collecting bubbles generated in the water-permeable porous tube at the upper part and removing it with a syringe, but it is necessary to insert the injection needle each time, the operation is complicated, and air-tight leak by repeating many times. There is also a concern of
Neither of them has become popular.

In order to maintain this system continuously, it is essential to remove the generated free air, so various studies have been made, and it is a fixed idea to start the pump appropriately and circulate the water. As a method for solving this problem, as disclosed in Japanese Patent Publication No. 3-51373, a method of circulating water while removing negative pressure by a vacuum pump to remove air bubbles, and Japanese Patent Laid-Open No. 5-123065 are disclosed. In the siphon principle, a method of circulating water to remove air bubbles has also been developed, but there were problems such as the service life of the pump.

[0005]

The above-mentioned method is a good method in terms of removing bubbles, and water can be transferred smoothly. However, when actually applied on a large scale, the negative pressure value in the circulatory system fluctuates depending on the location, which causes a new problem that the amount of water supply is different and, as a result, the growth of cultivated crops is different. In other words, when water is circulated, a pipe resistance is generated in the pipe, and there is a considerable difference in absolute value of negative pressure between the porous pipe on the water supply side and the permeable porous pipe on the discharge side. May occur. This is remarkable when the system is actually implemented on a large scale in farmland and the water-permeable porous pipes are connected in series for 20 to 30 m.

[0006] In addition, when it is attempted to manage the cultivation of an extremely small-scale flower pot by this negative pressure difference irrigation system,
It will be extremely expensive. Therefore, the present inventors have made various studies to solve these various problems and find a system that is compact, inexpensive, and does not impair the advantages of the negative pressure differential irrigation system, and it is surprising that water is not constantly circulated. Also, both air bubbles and water in the pipe are intermittently discharged out of the system,
The present invention has been completed by finding that the object can be sufficiently achieved by newly inhaling water.

[0007]

That is, the gist of the present invention is to provide a container for accommodating a soil layer in the upper part and a water storage part in the lower part thereof, in which a water-permeable porous tube is embedded, Saturate the water from the reservoir under negative pressure in the quality pipe, and the water in the water-permeable porous pipe is separated by the difference between the negative pressure in the soil water in contact with the water-permeable porous pipe and the negative pressure in the water-permeable porous pipe. A negative pressure differential irrigation system configured to leach a capillary into soil, wherein a flow path connecting a water-permeable porous tube and a water storage section or a branch tube thereof is provided with a stretchable and variable volume portion, By applying and releasing pressure to that part, pushing the gas generated in the flow path together with the water in the flow path, and then inhaling the water, a means for removing free air in the flow path is provided. It is equipped with a negative pressure differential irrigation system. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, in the present invention, a soil layer is stored in the upper part of a container, and a water storage part is stored below it.
The soil constituting the soil layer is generally natural soil and artificial soil such as culture soil, but even if it does not contain organic matter, it can be used for plant cultivation by the negative pressure differential irrigation system of the present invention. If there is, it is not particularly limited. In the present invention, since the essential water can be constantly supplied to the plant, the soil as the water retaining layer may be relatively small. The thickness of the soil layer can be appropriately selected according to the size of the container.

The water storage section stores water to be leached into the soil by the method described later, and the kind of water is not limited as long as it is suitable for plant growth. In this case, fertilizers, pesticides and the like can be dissolved if necessary. The size of the water storage part can be appropriately selected according to the size of the container, or can be divided into a plurality of parts that are electrically connected to each other. The shape of the container can be arbitrary, such as various planters and flower pots, and the size can be appropriately selected according to the purpose. Further, the material thereof is not particularly limited, but for example, plastics, plastics composite materials and the like are suitable.

In the present invention, a water-permeable porous tube is embedded in the soil layer. There is no particular restriction on the depth of burial, and depending on the thickness of the soil layer, it is usually 5 to 5 from the soil surface.
About 0 cm is preferable. If it is too shallow, it is disadvantageous in that it is easily affected by the temperature of the surface of the earth and water easily evaporates, and if it is too deep, it becomes difficult to reach the root zone of the plant, which is not preferable.

Generally, the material of the water permeable porous tube is preferably water permeable ceramics, water permeable concrete or water permeable porous glass, but it is preferably a sintered metal, polyethylene, polypropylene,
It is possible to use a water-permeable porous molded body made of rubber or other plastics, and a cylindrical material made of a material that can be used as a filter material. A hydrophilic material or a material which has been subjected to a hydrophilization treatment is preferable from the viewpoint of allowing water vapor or water to pass therethrough. These water-permeable porous materials have a pore size of 0.01 to 20.
It is desirable to have pores in the range of about 0 μm. If it is smaller than this, clogging easily occurs during use and the flow resistance of the fluid is large, so the flowability of water is poor. It tends to flow in, making it difficult to maintain negative pressure. A particularly desirable pore size is in a range of about 0.1 to 50 μm, and a pore size distribution is particularly preferable. In particular, a cylinder having a pore diameter of about 10 μm obtained by molding and firing porcelain clay having a large amount of quartz is preferable.

These porous materials are usually formed into a tubular shape and used as a water-permeable porous tube. The inner diameter, wall pressure, and length are not particularly limited, but if it is too small, the resistance when water flows is large, and if it is too large, a large amount of water is needed to flush out the bubbles generated or mixed inside. It is necessary to circulate. Therefore, the inner diameter is usually 3-100.
mm, preferably 5 to 50 mm, wall thickness 1 to 30 m
m, preferably 3 to 15 mm, and the length is not particularly limited, but flexibility such as ceramics is poor depending on the material,
It is possible to reduce the number of connection points by making the length short when the material is easily broken by flexural stress and lengthening the material having high flexibility such as a plastic material. In order to connect a plurality of porous pipes, it is common to use a tube such as polyvinyl chloride or polyethylene, or a pipe material, and it is convenient to use a metal pipe, a pipe connector, or the like. At the time of connection, it is preferable to use a tube or the like having a smooth inside, and further to prevent a pressure loss from occurring by preventing the tube diameter from changing rapidly.

In the present invention, the water in the water storage portion provided under the water permeable porous tube is conducted to the water permeable porous tube, and the flow of water between the porous tube and the piping material and the water storage section is made. Water is saturated in the channel, the water becomes stationary, and the pressure in the pipe becomes negative. The adjustment of the negative pressure may be performed, for example, by providing a minimum height difference in which the negative pressure is generated in the target shape, and the change in the negative pressure difference due to the decrease in the water level of the water storage part due to water consumption is allowed in the target device. It can be solved as a problem within the possible range.

In the present invention, by adopting such a constitution, the water in the water-permeable porous tube is differentiated due to the difference between the negative pressure of the soil water in contact with the water-permeable porous tube and the negative pressure in the water-permeable porous tube. Can be leached by capillary into the soil. In this case, as described above, the water in the flow path is in a stationary state, but only the amount of water that is capillary leached into the soil is supplied from the water storage section. The water can be supplied to the water storage portion from a water supply port provided above the liquid surface of the water storage portion, for example.

The present invention, in such a negative pressure irrigation system, comprises free air removing means capable of removing the air in the flow path. That is, in the present invention, a stretchable hollow rubber ball or a bellows-like suction / discharge fluid suction / discharge tool is provided in the flow path or its branch pipe, and is pushed or released or compressed. By repeating the operation of opening and releasing for several times, the released air can be easily discharged out of the system together with the water in the flow path, and the negative pressure state can be easily restored to the original state.

The size of the expandable and contractible hollow rubber ball and the bellows-like suction / discharge fluid suction / discharge tool are small when the size is large compared to the total amount of water filled in the flow path. The gas generated in the flow path can be discharged to the outside of the system by only the replacement, but if it is small, the number of necessary operations will increase. Usually, if it is small, you can grasp it with your hand or release it.
If it becomes larger, it will be a fugo type, and you will have to repeat stepping and releasing with your foot. These operations can be appropriately performed in a short time as necessary, but it is not always necessary to perform them every day.

When the expandable and contractible hollow rubber spheres are mounted in series in the flow path, it is preferable that the rubber spheres have openings at both ends. When a branch pipe is made from a flow path and a stretchable hollow rubber ball or a bellows-like fluid suction / discharge device is attached, a rubber ball with a single opening (rubber dropper), made of plastic It is preferable to use the bellows (eg, polypropylene bellows type dropper). Further, when the suction port and the discharge port of water are taken out from the flow path as side pipes and a bellows type manual pump is connected thereto, the shape thereof is not particularly limited as long as it has a check valve. For example, an oil pump used for pumping kerosene, a Hugo type foot-operated pump used as an inflator for a rubber boat, or the like can be used. These free air removing means can be installed, for example, in the above-mentioned device by providing a space between the soil layer and the water storage. It is also possible to provide a hook or the like on the side surface and hang it on it.

FIG. 1 shows an embodiment of the system according to the invention. The container 1 contains a soil layer 2 and a water storage part 3 below the soil layer 2. In the soil layer 2, a water-permeable porous tube 4 is provided.
Is buried. The porous tube 4 is electrically connected to the water in the water reservoir 3 by the tubes 5 and 5 '(7: water supply port, 8:
Drain). Negative pressure is set on the water surface of reservoir 3 and soil (2).
It is performed by the difference in height with the inside porous tube 4. Reference numeral 6 is a free air removing means, and for example, A to E configurations as shown in FIGS. 2 to 6 can be adopted. A: Rubber ball with two openings (rubber ball with check valve) B: Rubber ball with one opening (dropper) + check valve C: Plastic bellows with one opening (Dropper) + check valve D …… Plastic bellows with check valve (oil pump) E …… Plastic bellows with check valve (air pump for rubber boat) In addition, 9 in the figure is a water gauge and 10 is the bottom plate Show.

[0019]

According to the present invention, a compact and inexpensive negative pressure irrigation system can be obtained. That is, the advantages of negative pressure differential irrigation can be utilized, and the labor of irrigation and the damage of over-irrigation can be prevented to facilitate plant cultivation.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a negative pressure differential irrigation system of the present invention.

FIG. 2 is a diagram showing an embodiment of free air removing means 6 in the present invention.

FIG. 3 is a diagram showing an embodiment of free air removing means 6 in the present invention.

FIG. 4 is a diagram showing an embodiment of free air removing means 6 in the present invention.

FIG. 5 is a diagram showing an embodiment of free air removing means 6 in the present invention.

FIG. 6 is a diagram showing an embodiment of free air removing means 6 in the present invention.

[Explanation of symbols]

 1 Container 2 Soil Layer 3 Water Storage Section 4 Permeable Porous Tube 5 Tube 5'Tube 6 Free Air Removing Means

Claims (2)

[Claims] 1. A container for accommodating a soil layer in the upper part and a water storage part in the lower part, wherein a water-permeable porous pipe is buried in the soil, and water from the water storage part is stored in the water-permeable porous pipe. Saturated under pressure, the difference between the negative pressure of soil water in contact with the permeable porous tube and the negative pressure in the permeable porous tube was designed to allow the water in the permeable porous tube to leach into the capillary into the soil. A negative pressure differential irrigation system, in which a channel that connects the water-permeable porous tube and the water storage section or a branch tube thereof is provided with a part that is expandable and contractible and its volume is variable, and pressure is applied to that part and released, By pushing out the gas generated in the flow channel together with the water in the flow channel and then inhaling the water,
A negative pressure differential irrigation system comprising means for removing free air in the flow path. 2. The negative pressure differential irrigation system according to claim 1, wherein check valves are provided in front of and behind the portion that is expandable and contractible and whose volume is variable.