JPS6339865B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a soil moisture indicator.

In order to properly grow cultivated plants, an appropriate water supply without oversupply is necessary. Water supply is essential not only for plants growing indoors, but also in many cases to supplement rainwater for plants growing outdoors.
However, if a plant receives too much water, root rot may develop, resulting in weakness and even death.

Overwatering, giving plants too much water at once, can be easily prevented by providing suitable drainage means, such as drainage holes for indoor plants.
Such drainage holes allow excess water that is not absorbed by the soil to seep out of the soil and the root growth area of the plant. Pots with such drainage holes usually have an external container to collect such water. Alternatively, drainage can be provided by placing a layer of rocks or other material at the bottom of the pot beneath the soil.

Plants with adequate drainage means, such as those described above, or plants grown above ground, will not be able to avoid supercharging, not by receiving too much water at once, but by being watered too frequently. It may cause harm. Therefore, it is usually recommended by plant growth experts that the soil in which plants are potted be allowed to dry thoroughly between waterings. This is a general empirical rule for the majority of cultivated plants. There are some exceptions, such as succulents that are kept virtually dry for long periods of time, and ferns that are kept in constantly moist soil, but most plants require a sufficient water supply upon receipt shortly after drying. It flourishes best.

The appropriate time interval between water applications (hereinafter referred to as the wet-dry soil cycle) varies depending on many factors. It varies depending on the characteristics of the individual plant, and the amount of water taken up by the plant's roots depends not only on the age of the plant but also on the time of the year. Most plants go through a period of low water demand during the winter.
Another factor is the composition of the soil around the roots. Different soils hold different amounts of water. Environmental conditions also increase moisture content by affecting the rate of evaporation of water from the soil.
You can change the drying cycle. These environmental conditions also include factors such as atmospheric temperature and humidity.

Determining the appropriate watering time for any individual plant requires observation of the plant and/or testing of soil moisture content. Plant leaves often droop when the plant needs water. On the other hand, overwatering a plant can also cause its leaves to droop. Therefore, it is not practical to determine the appropriate water supply time solely by observing plants, especially for people who do not have extensive experience in plant cultivation.

As a second method to determine water needs of plants,
Testing soil by touching the ground surface is also not always reliable. This is because the upper layer tends to dry more quickly than the lower layer due to evaporation from the ground surface. Therefore, testing the soil just below the surface is the most preferred method of determining soil moisture. This type of manual test requires repeated stirring of the soil, so if you need to apply this method to a large number of plants,
It will waste your time unreasonably.

Devices are known for measuring the moisture content of the soil directly below the surface by visual observation, but they have significant drawbacks for use in the home or office or garden. Two categories of these known devices can be considered. The first category includes U.S. patent no.
2801538, U.S. Patent No. 2878671, U.S. Patent No.
These include complex moisture meters such as those disclosed in US Pat. No. 3,026,718 and US Pat. No. 3,045,477. These moisture meter indicators determine soil moisture by measuring variables such as osmotic pressure. Although these are sensitive instruments and appear durable, they are too expensive to be practical for occasional home or garden use.

A second category of indicators is covered by U.S. Patent No.
These include devices such as those disclosed in No. 3,824,844. The amount of hydrophilic material is becoming closer. These devices, when a part of them is inserted into the soil around the plant,
The water content of the hydrophilic material is now proportional to the water content of the soil. The hydrophilic material, or portion thereof, has been chemically treated so that it changes color as its water content changes. The moisture content can be determined by visually observing the color of this material. These devices are likely to be degraded by organisms in the soil since some of the hydrophilic materials are directly exposed to the organisms in the soil. These devices also
It is known that it responds slowly to changes in moisture content.

The present invention provides a moisture indicator that is particularly suitable for use in determining the wet-dry cycle of both indoor and outdoor potted plants and garden plants. The present invention also provides a soil moisture indicator that is not expensive to manufacture and that does not suffer from deterioration caused by direct contact of the moisture indicator with soil. Additionally, the present invention provides an indicator that is easy to install and requires occasional visual observation. Additionally, the present invention provides a soil moisture indicator that is reliable over time and accurately reflects plant water needs.

The present invention utilizes adsorbents that are chemically treated to suitably change color with water content. Such materials are, for example, water-absorbing supports impregnated with compositions containing cobalt chloride that appear pink in color when exposed to a humid atmosphere and blue in color when exposed to a less humid atmosphere. Conveniently, it is a sheet of material. The use of cobalt compounds as moisture indicators is well known in the art, e.g. U.S. Pat. No. 2,460,071;
No. 2,460,073, US Pat. No. 2,580,737 and US Pat. No. 3,246,758. The content of cobalt compounds and the presence of other chemicals in the adsorbent
Sensitivity to moisture can be effected not only with respect to the amount of moisture that affects the color change, but also with respect to the time over which the color change occurs. The special composition of the indicator material used in the invention is therefore another feature of the invention.

It is important according to the invention that the indicator used does not turn pink, indicating the wet phase of the wet-dry cycle, until the plant's soil is well watered.
Therefore, in a preferred embodiment of the invention:
A chemical is mixed into the indicator paper that increases the humidity level where the indicator changes color.

A general object of the present invention is to provide an inexpensive and accurate soil moisture indicator that is not only simple and practical to use, but is also free from deterioration by organisms in the soil.

Other objects of the invention will become apparent in view of the following description and the accompanying drawings.

In the drawings, a moisture indicator according to one embodiment of the invention is indicated generally by the numeral 10 in FIG. The indicator includes a lower chamber 12 that is substantially cylindrical and supports an upper chamber 14. As best seen in FIGS. 3 and 4, the passageway 16 interconnecting the lower and upper chambers is completely covered by the membrane 18. Membrane 18 contains a moisture indicator composition that changes color in response to humidity in the lower chamber. The upper chamber shown in FIGS. 1-4 is constituted by a support collar 20 and a cap 24 whose outer periphery is dimensioned to fit snugly within the sides of collar 20. Further, as shown in Figures 1, 3 and 4, a retaining wall 30 is also supported by the collar and surrounds the indicator material 18 to prevent it from moving laterally.

Collar 20, sheet of membrane 18 and membrane retaining wall 3
0 is shown as a circle. Of course, it is clear that other shapes, such as square or diamond shapes or elaborate patterns, can also be used and still be within the scope of the invention. The relationship between the shape of the retaining wall and the shape of the membrane layer need only be such that the indicator material is effectively retained. Retaining wall 3
0 does not have to be a continuous wall. A suitable notch or flange or any other retention means to prevent lateral movement may be used. Upper chamber 14 in which the membrane is placed
The type and shape of the main body constituting the device are clearly shown in FIG. 1, and the symmetry of the device shown in FIG.
It is being implemented.

The adsorbent membrane 18 is, according to the invention, placed above the soil surface and protected from contact with the soil by being placed in an upper chamber 14 which is at least partially transparent. The adsorbent membrane is placed so that a portion of it extends across the aperture 16 in the lower surface of the upper chamber. The aperture 16 interconnects the upper chamber 14 with the lower chamber 12, which can be in the form of the axial cavity of the stem portion of the device.

The present invention can be broadly described as two chambers communicating with each other by a passageway substantially covered by an adsorbent membrane carrying an indicator composition. The upper chamber 14 is partially transparent so that the indicator material can be easily viewed. In one preferred embodiment of the invention, the upper chamber 14 is provided with vents, such as air vents 32, to the outside air. The lower chamber has a bottom aperture 26 and is inserted into the soil so that the moisture content of the soil can be tested at a point below the surface of the soil.

The lower chamber 12 can be substantially in the form of a cylinder or a stem supporting the upper chamber 14 and is easily inserted into or removed from the soil thanks to the cylindrical shape of the stem. The lower chamber within the stem has a smaller flow cross section 12 than the upper chamber.

The stem portion 12 of the device 10 is inserted into the soil along a substantial portion of its length. The stem portion 12 supporting the upper chamber interconnects the indicator material with the soil at a depth below the soil surface. Indicator material 18 separates the upper and lower chambers and is in contact with the air in both chambers. Therefore, the air entering this stem or lower chamber 12 will tend to be in equilibrium with the moisture content of the soil below the soil surface, and therefore the moisture content or humidity of the air in the stem will be in equilibrium with the soil moisture content below the soil surface. varies as a function of water content.

Although the upper chamber may be enclosed to avoid sensitivity of the indicator material to the humidity of the surrounding environment, it is surprising that the upper chamber has an outlet or air hole 32, such as a series of holes in the bottom of the upper chamber. It has been found that the sensitivity of the indicator material to changes in soil moisture content increases when placed between the soil and the outside air. A moisture indicator having an upper chamber vented to the atmosphere and a lower chamber facing the subsurface soil and an indicator material interconnecting both chambers comprises a further preferred embodiment of the invention. There is.

As mentioned above, the composition of the indicator material impregnated into membrane 18 is a feature of the present invention. The indicator material of the invention does not come into direct contact with the soil whose water content is to be determined according to the invention. One side of the indicator material is in contact with the air in the lower chamber and its humidity is a variable to which the indicator material responds.

Membrane 18 has a moisture absorbent substrate, such as absorbent paper. Blotting papers suitable for such uses are well known in the art.

When such paper is impregnated with a moisture indicator composition, such as cobalt chloride, it produces a visible color change when exposed to a particular relative humidity.
The adsorbent film absorbs an amount of water that varies with the relative humidity of the environment, and this water acts on the indicator or composition to produce a visible color change.

The color change of cobalt chloride results from an equilibrium reaction, for example: Cobalt chloride generally has a blue color when exposed to atmospheric relative humidity up to about 55% and turns pink above 55%. The time required for the indicator to change color when exposed to the relative humidity that causes the change depends, among other variables, on humidity. That is,
Indicator compositions containing cobalt chloride change from blue to pink more quickly when exposed to 90% relative humidity than when exposed to 70% relative humidity, although the color change will eventually occur in both cases. wake up

The upper cap 24 in FIG. 1 is shown as completely transparent, allowing any color changes to be seen from various angles.

The support collar 20 of the upper chamber shown in FIGS. 1, 2 and 3 includes holes or vents 32 so that the chamber is open to the atmosphere. Although these holes are shown in the lower wall of the upper chamber, support collar 20, it is contemplated by the present invention that such vents be located elsewhere.

As best seen in FIG. 2, the retaining wall 30 of the membrane 18 is provided with a notch 40 along its inner circumference. The notch 40 suppresses upward movement of the membrane and prevents it from being accidentally removed.

FIG. 3 shows that the membrane 18 is located above the substantially central passage 16 interconnecting the upper chamber 14 and the lower chamber 12 forming a passage from the upper chamber to the aperture 26 in the lower chamber. The location is most clearly shown.
As shown most clearly in FIG. 3, the lower chamber 12 is
It is preferred to have an inwardly tapered lower portion or joint 28 to facilitate insertion of the indicator into the soil and provide support for the indicator.

FIG. 3 also shows the preferred positioning of the indicator in the soil, i.e., for example, the upper chamber 14 is about 0.158 cm to 0.635 cm (about 1/16 to 1/4
inches) placed above.

The indicator shown in FIG. 4 is substantially the same as that shown in FIGS. 1-3, only without the vent 32 between the upper chamber and the surrounding atmosphere.

Membrane 18 may be a sheet of blotting paper or other absorbent material impregnated with an indicator composition. A preferred method of impregnating the membrane is by immersing the membrane in a solution containing the indicator composition. Although aqueous solutions can be used, the solvent that is subsequently evaporated from the adsorbent will be chosen based on the solubility of the composition.

The indicator composition used in the present invention includes cobalt chloride. Preferably, however, cobalt chloride is used in combination with an agent that produces a color change at relative humidity in the range of about 80% to about 90%, e.g., cobalt chloride is combined with a thiocyanate salt such as potassium thiocyanate. Use in combination. The inclusion of other anions and cations by adding salts such as sodium chloride and calcium chloride to enhance color is also contemplated in the present invention.

Other methods of saturating adsorptive materials with solutions containing the above-mentioned chemicals and then removing the solvent are well known in the art, and the invention is not limited to any particular matter of preparing the indicator composition. .

The preferred indicator composition is best illustrated by the weight ratio of cobalt chloride to thiocyanate. The present invention preferably ranges from 1:0.5 to 1:
It is contemplated to use a composition containing cobalt chloride and potassium thiocyanate in a weight ratio in the range of 0.8.
The weight ratio of cobalt chloride to potassium thiocyanate is 1:
A ratio of 0.6 to 1:0.7 is a more preferred embodiment of the invention. Of course, equivalent amounts of other thiocyanates, such as sodium or calcium salts, can also be used in place of potassium thiocyanate.

The invention is further illustrated by the following examples which disclose impregnating a blotting paper with an indicator composition.

Example 28 g of cobalt chloride, 15 g of sodium chloride, 4 g of calcium chloride (anhydrous) and potassium thiocyanate
A suitable indicator material was prepared by dipping blotting paper into a solution of 19 g diluted with water to give a total solution volume of 380 ml. The paper was immersed in the solution so that it covered both sides. The paper was then hung to air dry.

Although the exact principle of operation of the present invention is not fully understood, it is believed that the moisture content of the air in the lower chamber defined by the stem varies as a function of soil moisture content. The indicator composition on membrane 18, exposed to both the upper and lower chamber atmospheres, responds to the highest humidity. Therefore, if the humidity on one side of the above paper is, say, 90% and that on the other side is lower than 55%, the paper will respond to the highest humidity, and if the paper contains cobalt chloride. It turns pink. This theory provides an explanation for the excellent results obtained in embodiments of the invention in which the upper chamber is provided with a vent to outside air. When watering the plant soil, the humidity in such a lower chamber is above 70 to 80%, causing the indicator material to turn pink. As the soil dries out, the humidity in the basement decreases. A vent in the upper chamber "dries" the paper. The paper allows moisture to evaporate into the atmosphere, allowing the vents to track soil conditions more quickly. In other words, the vent attempts to maintain the paper at the correct moisture level by evaporating any moisture in the paper that exceeds the indoor moisture level. If the indoor humidity level is at a certain level, e.g.
When it drops below 70%, the paper turns blue. The indicator composition is not affected by normal room humidity because it does not indicate humidity conditions when the relative humidity of the atmosphere is less than about 50% to 65%.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a moisture indicator as an embodiment of the present invention. FIG. 2 is a cross-sectional view of the moisture indicator of FIG. 1 taken along line 2--2. FIG. 3 is a cross-sectional view of the moisture indicator along line 3--3. FIG. 4 is a partially cutaway side view of a moisture indicator as another embodiment of the present invention. 10...Moisture indicator, 12...Lower chamber, 14...Upper chamber,
16... Passage, 18... Membrane, 20... Support collar, 24...
Cap, 26...Bottom opening, 28...Tapered joint, 30...Retaining wall, 32...Vent hole, 40...Notch.

Claims (1)

[Scope of Claims] 1. Upper chamber; Lower chamber; The lower chamber has an opening at the bottom and is inserted into the soil below the surface so that the humidity in the lower chamber is related to the wetness of the soil. passage means interconnecting said upper chamber and said lower chamber; a moisture indicator composition that causes a color change when the relative humidity in said lower chamber is higher than at least 70%; said upper chamber and said lower chamber; a moisture indicator support disposed across said passage means interconnecting said chamber and supporting said indicator composition; and said upper chamber having a transparent portion for viewing the color response of said indicator composition. A soil moisture indicator consisting of: 2. An upper chamber consisting of a support collar and a cap of transparent material placed on the support collar and provided with ventilation holes to the outside air; having an opening at the bottom and intended to be inserted into the soil. a lower chamber provided with a system section that connects; passage means for interconnecting said upper chamber and said lower chamber; said passage means disposed across said passage means for interconnecting said upper chamber and said lower chamber; A soil moisture indicator comprising: a membrane; and an indicator composition contained in the membrane that produces a color change in response to relative humidity above about 70%.