JPS6330744A - Soil moisture meter - Google Patents

Abstract

PURPOSE:To properly determine a moisture replenishing period or moisture replenishing quantity, by mounting a molded body composed of a water absorbable and expansible polymer material to the lower part of a rod like body to which graduations are applied in a state extensible and contractable in the axial direction thereof. CONSTITUTION:A soil moisture meter 10 is constituted so that graduations 14 are applied to a metal rod 12 at a proper interval and a ring part 16 for hanging is provided to the upper end of said rod 12 and a push-in cone 18 is provided to the lower end thereof and the rod 12 is inserted in the center hole of a cylindrical molded body 20 composed of a water absorbable and expansible polymer material to fix the moisture meter 10 only by the upper surface of the cone 18, that is, the lower end of the molded body 20 so as to make the same extensible and contractable in the axial direction thereof. When the moisture meter 10 is pushed in soil by utilizing the cone 18, the molded body 20 absorbs moisture in soil by the difference between osmotic pressures inside and outside of the polymer material or the compatibility of the polymer material with water to expand as shown by a drawing B. This water absorbing action is similar to the action of the root of a plant absorbing moisture in soil. Therefore, by reading the expanding length of the molded body 20 by graduations 14, the quantity of moisture utilizable by a plant in embedded soil can be measured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for measuring moisture in soil by burying it in soil and measuring its water absorption and expansion state. The present invention relates to a soil moisture meter in which a molded body made of a water-absorbing and swelling polymeric material is attached to the lower part of a rod-shaped body, and moisture can be measured from the amount of expansion and contraction in the axial direction.

[Prior Art] There are many industrial fields that require the growth of plants such as trees, vegetables, and flowers, such as fruit tree cultivation, forestry, civil engineering work for roads, and agriculture. If moisture in the soil is depleted, stunted growth or death will occur, so it is important to provide plants with appropriate water supply at the appropriate time to maintain healthy growth. Particularly in greenhouse cultivation, hydration is artificially provided, and if this is not done properly, it can be harmful to the plants. Therefore, it is important to accurately understand the amount of water available to plants in the soil.

A tensiometer is a device that measures the amount of moisture in soil. This consists of a main body, for example, a mercury pressure gauge, and a sensing part, which is buried in the soil and has a porous bisque cup as the sensing part. It is connected to the main body with water, and is configured so that the moisture status can be read in mercury columns using a mercury pressure gauge. It is also possible to calculate the pF value from this value.

[Problem to be Solved by the Invention 1] However, the conventional soil moisture meter as described above is not common because the device is complicated, very expensive, and difficult to handle.
Currently, it is only used at agricultural experimental stations.

Moreover, although conventional measuring instruments can measure the amount of water in the soil (soil water suction pressure), this does not necessarily lead to determining the amount of water available to plants. This is because, depending on the type of soil, there is generally a large difference between the amount of water in the soil and the amount of water available to plants.

For this reason, the reality is that determining the timing and amount of hydration depends solely on ``feelings'' and ``experience.''

The present invention was made in view of the above-mentioned state of the art, and its purpose is to accurately and appropriately determine the timing and amount of water replenishment to soil, which previously relied solely on intuition and experience. To provide a compact and inexpensive soil moisture meter capable of determining soil moisture.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, has a molded body made of a water-absorbing and swelling polymeric material attached to the lower part of a rod-shaped body with graduations, so as to adjust the water-absorbing state of the molded body. This is a soil moisture meter with a structure that allows it to be expanded and contracted in the axial direction according to the conditions.

The water-swelling polymer material used here is a water-swelling polymer compound '1llff (pure compound) mixed with a material such as rubber or plastic and molded into a predetermined shape. A water-absorbing and swelling polymer compound refers to a substance that can absorb several times to hundreds of times its own weight in water, and can be made from a variety of conventionally known materials, such as starch-based or polyacrylic acid-based materials. can.

The shape of the molded object is not particularly limited, but it may have a structure in which it is made into a cylinder and a rod-shaped object is inserted inside and fixed only at the lower end, or a structure in which it is made into a rectangular shape and is sandwiched between rod-like members from both sides. etc.

[Function] A water-absorbing and swelling polymer material absorbs water and expands due to the difference in osmotic pressure between the inside and outside of the polymer or the affinity between the polymer and water.

This water absorption is very similar to the way plant roots absorb water from the soil. Therefore, by embedding a molded body made of a water-absorbing and swelling polymer material in the soil and allowing it to absorb the moisture in the soil, and then taking it out as appropriate and reading the axial length using a scale, it is possible to accurately determine the amount of moisture that can be used by plants in the soil. can be grasped.

Since this soil moisture meter utilizes the water absorption mechanism described above, it is possible to accurately measure the amount of water available to plants even if the soil type is different and the amount of water is different.

[Example] FIGS. 1A and 1B are explanatory diagrams showing an example of a soil moisture meter according to the present invention. This soil moisture meter 10 has scales 14 attached to a rod 12 made of metal or plastic at appropriate intervals, a ring portion 16 for hanging at the upper end, and a cone 18 for pushing in at the lower end, and has water absorption and swelling property. The structure is such that the rod 14 is inserted into the center hole of a cylindrical molded body 20 made of a polymeric material and fixed only by the upper surface of the cone (the lower surface of the molded body 20).

Such a soil moisture meter 10 can be used, for example, in the vicinity of a fruit tree 22 as shown in FIG. 2, or in the vicinity of a plant 22 as shown in FIG.
It is used by pushing the cone 18 into the soil of the flowerpot 26 in which the cone 4 is planted. As mentioned above, the molded body 20 made of a water-absorbing and swelling polymer material absorbs moisture in the soil due to the difference in immersion pressure inside and outside the polymer or the affinity between the polymer and water, as shown in FIG. 1B. expands to. This water absorption action is combined with the action of plant roots absorbing water in the soil, and the amount of water available to plants in the soil is indicated by its expansion and deformation.

Therefore, by reading the expansion length of the compact 20 extracted from the soil using the scale 14, it is possible to determine the amount of moisture available to plants in the soil in which the compact is buried. If you use color-coded scales to indicate the range of appropriate moisture depending on the soil type, the area that requires irrigation, etc., even an inexperienced worker can always keep an eye on the moisture in the soil. It can be maintained and managed in an appropriate state.

The expansion of the molded body 20 spreads not only in the axial direction but also in the radial direction, so if more accurate judgment is required, the ring part 16 provided at the upper end of the rod 12 can be used to suspend it on a spring scale or the like. You may also lower the weight to find the weight change.

FIGS. 4 and 5 show examples of soil moisture measurement results using the product of the present invention. Figure 4 shows the rate of change in the length of compacts (L Lo) /
This is the result of finding Lo. Furthermore, FIG. 5 shows the relationship between the soil moisture suction pressure pF value and the rate of change in the length of this soil moisture meter using a tensiometer. The molded body of water-absorbing and swelling polymer material used in this soil moisture meter is made by mixing an acrylic acid-based polymer compound into natural rubber. The soil sample is silt/sandy soil.

The sixth cabinet shows another embodiment of the present invention.

In this example, a molded body 3 made of a water-absorbing and swelling polymeric material is used.
0 is shaped like a strip and rods 32 are arranged on both sides of the strip. Further, FIG. 7 shows a structure in which the molded body 34 is made into a cylindrical shape, and a rod 36 is inserted therethrough and its lower end is bent and fixed. In any case, the molded body 30.34 is positioned below the rod 32.36 and fixed only at the lower end, making it expandable and contractible in the axial direction, as in the previous embodiment. Therefore, the basic operations can be considered to be the same.

FIG. 8 is an explanatory diagram showing still another embodiment of the present invention.

In this embodiment, a structure as shown in FIG. 1 is assumed, and a cylindrical body 40 made of plastic or the like is fixed to the upper end of a cylindrical molded body 20 so as to be loosely fitted to the rod 12. To insert this soil moisture meter into the soil, embed it at a depth such that the soil surface 42 is located exactly at the middle of the plastic cylindrical body 40. When the molded body 20 absorbs soil moisture and expands. , axial expansion occurs, and the cylindrical body 40 is accordingly displaced upward as shown by the imaginary line in the figure. Therefore, the position of the upper end surface of the cylindrical body 40 is set to 1 on the scale.
4, it is possible to measure the amount of expansion and deformation in the same state without having to pull it out of the soil each time for measurement.

[Effects of the Invention] The present invention provides a soil moisture meter in which a molded body made of a water-absorbing and swelling polymeric material is attached to the lower part of a rod-like body with graduations as described above, so that it can expand and contract in the axial direction according to its water absorption state. that's why,
It is now possible to easily measure the moisture status in the soil that can be used by plants, and without the need for special skills, making it possible to manage soil moisture, which is the most important aspect of growing plants, without relying on intuition or experience. It has excellent effects that can be done scientifically and properly.

Further, the soil moisture meter according to the present invention has an extremely simple structure and can be constructed at low cost, so that it can be installed for each tree or flower pot, making it possible to properly manage soil moisture.

By using the soil moisture meter according to the present invention, it is possible to improve the quality and yield of crops, and it also has great secondary effects, such as draining excess water and saving water.

[Brief explanation of drawings]

FIG. 1A is an explanatory diagram showing one embodiment of the soil moisture meter according to the present invention, FIG. 1B is an explanatory diagram showing the state when it absorbs water and expands,
FIG. 2 and FIG. 3 are explanatory diagrams showing examples of the usage state,
Figure 4 is a diagram showing the relationship between water content and water absorption expansion change rate;
Figure 5 is a diagram showing the relationship between pF value and water absorption expansion change rate,
FIG. 6A is an explanatory diagram showing another embodiment of the present invention, FIG. 6B
7A is an explanatory diagram showing another embodiment of the present invention, FIG. 7B is a bottom view thereof, and FIG. 8 is still another embodiment of the soil t1 moisture meter according to the present invention. It is an explanatory view showing an example. DESCRIPTION OF SYMBOLS 10... Soil moisture meter, 12... Bar, 14... Scale, 18... Cone, 20... Molded object made of water-absorbing and swelling polymer material t-1. Patent Applicant Osei Geology Co., Ltd. Representative Minoru Shigemi Figure 4 Oto 20 30 40 Water content (%) Figure 5 ρF value Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A soil moisture meter characterized in that a molded body made of a water-absorbing and swelling polymeric material is attached to the lower part of a rod-shaped body with graduations so that it can expand and contract in the axial direction depending on its water absorption state.