WO2018147816A1

WO2018147816A1 - A self-controlled irrigation apparatus

Info

Publication number: WO2018147816A1
Application number: PCT/TR2017/000023
Authority: WO
Inventors: Sabit ERŞAHIN
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-02-09
Filing date: 2017-02-09
Publication date: 2018-08-16
Anticipated expiration: 2019-08-09

Abstract

This invention relates to a self-controlled irrigation apparatus, which supplies water at a constant supply rate at a desired soil, depth and at a targeted soil, water hydraulic head during a targeted length of time. The precipitation and/or irrigation water is collected by a funnel and transferred to a porous cup at the plant root zone. Water in the reservoir is in contact with a porous cup mounted to a pipe extending to plant root zone, The porous cup holds the water and releases it when soil water hydraulic head drops below targeted level. The invention maintains the soil water potential at plant root zone constant during a targeted time period. The range of soil water hydraulic head that apparatus works depends on the pore-size of the porous cup and depth of the apparatus. The apparatus can help users save water, limits nutrient leaching, and decrease irrigation induced environmental pollution.

Description

A Self- controlled irrigation apparatus

Technical field

This invention relates to self-controlled irrigation apparatus, which supplies water at a targeted soil water matric head at targeted soil depth during a targeted length of time.

Background information and prior art

List of figures

The self-controlled irrigation apparatus is schematized in Figures 1/2 and 2/2. The references to the items in the figures are as follows:

Fig.1/2

1. Water reservoir,

2. Bubbling tower,

3. Precipitation collecting/refilling funnel,

4. A pipe, mounted to water reservoir.

5. A porous cup mounted to one end of the pipe,

6. A lid, which allows water transfer from funnel to water reservoir,

7. A resilient ring, which prevents air flow into reservoir, and

8. A filter that limits entrance of suspended matters into the system.

Figure 272

6.1. The lid,

6.2. A conic section, which is covered with a resilient matter,

6.3. Hinge, which controls movement of the rod that carries the lid.

Detailed Description of the Invention

1. The porous cap (5) is mounted to one end of the pipe (4).

2. A hole, just compatible with the size of pipe (4) with porous cup (5|, is open in soil and the pipe (4) with the porous cup (5) mounted, is placed in the hole.

3. The pipe (4) with porous cup (5) is further tightened by soil of the hole to make sure that a good contact is achieved between porous cup and soil.

4. The bottom of water reservoir (1) is mounted to the top of pipe at level of the soil surface, so weight of the reservoir is supported by soil surface, not the pipe (4) to avoid damaging of porous cup.

5. The bubbling tower (2) is placed, all the way down to porous cup (5), and then bubbling tower (2) is mounted to the reservoir,

6. The resilient ring (7) is placed around the joint of bubbling tower (2) to prevent air infiltration into water reservoir from the joint.

7. The funnel (3) is mounted to the bubbling tower (2).

8. The filter (8) is mounted to top of the bubbling tower to prevent infiltration of suspended matters in incoming air and water into the reservoir that may plug the porous cup

9. The reservoir is filled with water and the apparatus is started to operate. Soil water matric head (h) at and around the porous cap is conceptualized by equation

(1):

h = -0.3/d (1) where, h is the soil water matric head (cm), d is the diameter of largest pore in the porous cap (cm), and 0.3 is a constant. For example, a porous cup with largest pore diameter of 0.002 cm has a maximum matric head of -150 cm. When the porous cap and adjacent soil water is in equilibrium, the soil water around the porous cap (5) experiences the same -150 of cm matric of head.

Hydraulic head (H) of the soils in contact to the porous cup is controlled by matric head (h) created by porous cup + pressure head (p) induced by the water on the porous cup:

That is,

H = h+p (2)

The bubbling tower has three functions:

1. It controls air flow into the system under targeted hydraulic head,

2. It controls magnitude of pressure head (p), which standing water in the system exerts to the porous cup (5).

3. It keeps water supply rate constant against decreased water levels in the system. As water flows from the system to soil, water level in the system gradually decreases. The bubbling tower compensates the decrease, keeping the hydraulic head (pressure head + matric head) constant at the porous cup during the watering.

Also, the bubbling tower (2) can be used to adjust H at the porous cup (5). The porous cup (5) experiences water pressure exerted by standing water in the system. The H at porous cup (5) is therefore matric head + pressure head. The matric head always takes negative values, while pressure head takes positive values. For example, suppose we have a 1-m deep apparatus (water reservoir (1) + pipe (4)) with a porous cup (5) with a 0.002-cm maximum pore diameter. According to Eq. (1 ), the porous cup with a 0.002 cm largest pore diameter should create a matric head of -150 cm. If the system is full of water, it exerts 100 cm of pressure head to the porous cup, resulting in -150 cm + 100 cm = -50 cm of H (see Eq.2) in the porous cup. Therefore, soil adjacent to porous cup experiences -50 cm of H. On the other hand, when the lower end of the bubbling tower (2) is just at the porous cup, the porous cup experiences - 150 cm + 0 cm = -150 cm of H by Equation (2).

Rate of water flow from porous cup to soil is controlled by hydraulic conductivity (K.) of soil ai targeted H. Relationships among soil texture, K, H, and volumetric water content are highly complex. Therefore, if water flow rate from the porous cup (5) to soil is not adequate at the targeted H, the H can be further adjusted by tuning the depth of bubbling tower (2) as already explained above.

The funnel (3) collects precipitation water and transfers it to reservoir (1) through bubbling tower (2). The funnel (3) is also used for refilling the reservoir (1) with irrigation water.

The lid (6) allows water to flow from the funnel (3) to reservoir (1) when it is open and it prevents air flow to system when it is closed. The lid (6.1) is designed so it moves up and down by a rod, which is mounted to a hinge (6.3). When the pressure in the reservoir (1) becomes greater than atmosphere due to pressure exerted by collected rain water or filled irrigation water through the funnel (3) and bubbling tower (2), the lid (6.1) opens, allowing the air to escape from the reservoir. When the air pressure between reservoir and atmosphere becomes equal, the lid is closed due to its own weight. As negative pressure builds inside the reservoir as soil sucks water from the apparatus (1), the lid gets tighter since its conic section (6.2) is covered by a resilient material, stopping air flow from the atmosphere to the reservoir (1).

One example of intended use

Let an apple tree with active rooting depth of 80 cm in a soil with a loam texture be irrigated with a constant water supply at -300 cm of H (h+p), using the invented apparatus with a 50 cm deep and 30 cm wide cylindrical water reservoir (1). This needs an 80-cm long pipe (4) (the depth of porous cup can be neglected). The diameter of largest pore in the porous cup should be no greater than 0.001 cm according to Equation 1 and depth of bubbling tower should be extended up to porous cup (5) according to Equation (2). The apparatus is set up as shown in Figure 1/2 and started to operate.

Suppose that at -300 cm of H, the apple tree still shows symptoms of water shortage, suggesting that H be increased. In this case, we have two alternatives to increase H in root zone:

1. We can use a porous cup (5) with larger pore-size (say d≤0.002 cm).

2. We can decrease the depth of bubbling tower (2) in water, and this induces an increased pressure head (p) on the porous cup (2), which in turn, results in increased H at porous cup (5). For example when bubbling tower is completely submerged in the water, the pressure head at the porous cup is practically zero. However, suppose that we submerge the bubbling tower in water 50 cm instead of 120 cm (depths of water reservoir ( 1 ) + pipe (2)). This results in an H of -230 cm (h+p = -300 cm + 70 cm = - 230 cm), which results in H to increase.

Warnings of commonly used in the field

1. The soil volume around the porous cap (5), of which water content is affected by porous cup is highly depended on the soil texture, being greatest in a clay and smallest in a sand. This disadvantage can be limited adjusting the size of the porous cups to the soil texture.

2. Water flow-water potential relations are highly different in soils based on the soil texture. Therefore, porous cups with different pore-sizes can be used for soils with different textures. For example, porous cups (5) with 0.001-0.002 cm pore diameter may be used for clayey soils, 0.002-0.003 cm for loamy soils, and 0.003-0.004 cm for sandy soils. Also, as explained previously, the depth of bubbling tower (2) can be adjusted to increase/decrease water conductivity from porous cup (5) to surrounding soil.

Claims

1. The invention is a self-controlled irrigation apparatus comprising;

a. A water reservoir ( 1 )

b. A pipe (2) mounted to water reservoir (1 ),

c. A porous cup (5) mounted to the pipe (2),

d. A bubbling tower (2),

e. A funnel (3) connected to the water reservoir ( 1 ) via bubbling tower (2), f. A lid (6), mounted to the water reservoir (1),

g. A resilient ring (7), which prevents air infiltration into the water reservoir (1) at the joint of bubbling tower,

h. A filter, which filters suspended material in the incoming water and air to the water reservoir (1).

2. The porous cap (4) of claim 1 , which supplies water to soil under a controlled

hydraulic head of soil water at targeted soil depth during time of interest.

.

3. The bubbling tower (2) of claim 1, which controls water pressure head at the porous cup.

4. Bubbling tower (2) in claim 1 , which controls air intake of reservoir (1 ) under the targeted hydraulic head at the porous cup (S).

5. Bubbling tower in claim 1 , which maintains water supply from porous cup to soils at a constant rate.

6. The lid (6) of claim 1, which makes water flow from the funnel to reservoir possible.

7. The funnel (3) of claim 1 , which collects precipitation water and transfers it to water reservoir (1).

8. The funnel (3) of claim 1 , which can be used for refilling the water reservoir ( 1 ).