This is a continuation application of International Application No. PCT/JP2012/003369, with an international filing date of May 23, 2012, which claims priority of Japanese Patent Application No.: 2011-122999 filed on Jun. 1, 2011, the content of which is incorporated herein by reference.
The technical field relates to a plant cultivation structure and soil (soil structure) for plant cultivation that are applicable to hydroponic culture with use of sand having a water repellent property.
As to the technique for improvement of soil so as to be desired by human race at the level of the environment of the earth, in view of the food crisis, there is an attempt to improve the structure of soil for better growth of farm products as well as for better production efficiency. In particular, there has been made an invention relating to the improvement of soil as innovation for retaining water that is often insufficient in desertified land, in which sand itself existing enormously on site is utilized by applying water repellent coating thereto.
As an example of conventional improvement of soil, there has been made an invention in which a hydrophobic layer configured by hydrophobic particles is provided on soil including a water retaining agent with a layer of soil including no water retaining agent being interposed therebetween (see JP 3057304 B1, for example). As shown in
However, the soil structures described above still have issues.
The measure according to JP 3057304 B1 basically has the following defect. Specifically, because of provision of the hydrophobic layer 52, water poured on a ground surface 30 is unlikely to reach the water retaining agent layer 50. According to JP 3057304 B1, as shown in
However, still in this case, it is difficult for only an appropriate amount of water necessary for the plant is to reach the ordinary soil 51 or the water retaining agent layer 50 and be retained therein. There is a defect that the amount of supply needs to be controlled accurately. Even in a case where too much water is supplied, the water is excessively absorbed in the ordinary soil 51, or the excessive water remains on the water retaining agent layer 50. Therefore, air may not be appropriately supplied to the plant thereby to cause root rot. On the contrary, in a case where water is insufficient because the amount of water passing through the hydrophobic layer 52 is not controlled accurately, the plant cannot grow appropriately.
One non-limiting and exemplary embodiment provides a plant cultivation structure and soil for plant cultivation, which enable supply of requisite minimum water as well as supply of air to roots of a plant.
Additional benefits and advantages of the disclosed embodiments will be apparent from the specification and Figures. The benefits and/or advantages may be individually provided by the various embodiments and features of the specification and drawings disclosure, and need not all be provided in order to obtain one or more of the same.
In one general aspect, the techniques disclosed here feature: a plant cultivation structure comprising:
a water repellent sand layer that is formed by water repellent sand having surfaces to which water repellent coating is applied;
a plurality of water retaining layers scattered in the water repellent sand layer in a depth direction of the water repellent sand layer and capable of retaining water; and
a plant having roots located in the water repellent sand layer and being in contact with the water retaining layers such that the roots connect the plurality of water retaining layers.
These general and specific aspects may be implemented using a system, a method, or any appropriate combination of such a system and a method.
In the plant cultivation structure and the soil for plant cultivation according to the above aspects of the present invention, requisite minimum water can be supplied to plants individually in accordance with the different growth speeds of the respective plants. Furthermore, air can also be supplied to the roots of the plants. As a result, hydroponic culture can be enabled with high efficiency and high quality.
These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the embodiments thereof with reference to the accompanying drawings, in which:
Embodiments of the present invention are detailed below with reference to the drawings.
First, the basic concept of the present disclosure is explained.
Examples of the disclosed technique are as follows.
1st aspect: a plant cultivation structure comprising:
a water repellent sand layer including water repellent sand having surfaces to which water repellent coating is applied;
a plurality of water retaining layers scattered in the water repellent sand layer in a depth direction of the water repellent sand layer and capable of retaining water; and
a plant having roots located in the water repellent sand layer and being in contact with the water retaining layers such that the roots connect the plurality of water retaining layers.
According to the 1st aspect, requisite minimum water can be supplied to plants individually in accordance with the different growth speeds of the respective plants. Furthermore, air can also be supplied to the roots of the plants. As a result, hydroponic culture can be enabled with high efficiency and high quality.
2nd aspect: the plant cultivation structure according to the 1st aspect, wherein, in the plurality of water retaining layers, the water retaining layer in contact with the root of the plant retains water that is supplied from outside the water repellent sand layer to the plant and moves along the root of the plant.
According to the 2nd aspect, requisite minimum water can be supplied to the plants individually in accordance with the different growth speeds of the respective plants. Furthermore, air can also be supplied to the roots of the plants. The water is retained in the water retaining layers even while the water is not supplied. Therefore, air can also be supplied to the roots of the plants, thereby to achieve hydroponic culture with high efficiency and high quality.
3rd aspect: the plant cultivation structure according to the 1st or 2nd aspect, wherein each of the water retaining layers contains a manure composition.
According to the 3rd aspect, requisite minimum water and manure can be supplied to the plants individually in accordance with different growing speeds of the plants. Furthermore, air can also be supplied to the roots of the plants. As a result, hydroponic culture can be enabled with high efficiency and high quality.
4th aspect: the plant cultivation structure according to any one of the 1st to 3rd aspects, wherein the water retained in the water retaining layers contains a manure composition.
According to the 4th aspect, requisite minimum water and manure can be supplied to the plants individually in accordance with different growing speeds of the plants. Furthermore, air can also be supplied to the roots of the plants. As a result, hydroponic culture can be enabled with high efficiency and high quality.
5th aspect: the plant cultivation structure according to any one of the 1st to 4th aspects, wherein the water retaining layers are formed by sand with no water repellent coating.
According to the 5th aspect, the water retaining layers is formed by the sand with no water repellent coating, so as to have a water retentive property (in other words, a water absorbing property) and exert the water retentive property.
6th aspect: the plant cultivation structure according to any one of the 1st to 5th aspects, wherein each of the water retaining layers is formed into a downwardly convex circular arc shape in the depth direction.
According to the 6th aspect, when the plurality of plants are provided, the structure is compatible with the roots growing substantially concentrically in planar view, of the individual plants. Furthermore, the roots reliably pass through the water retaining layers even in a case where the roots grow randomly and unexpectedly in various directions. Therefore, such a structure is useful.
7th aspect: the plant cultivation structure according to any one of the 1st to 5th aspects, wherein the water retaining layers are scattered and layered in the depth direction.
According to the 7th aspect, the roots can grow by reliably passing through the water retaining layers.
8th aspect: the plant cultivation structure according to any one of the 1st to 7th aspects, wherein the water repellent sand layer has a concavity for supply of water, in a surface in a portion where the plant is planted.
According to the 8th aspect, there is provided the concavity for supply of water, so that the water is likely to be retained temporarily in the concavity. More specifically, for example, by supplying water from a watering pot or the like toward the concavity or the ground surface upon supplying water, the water can be easily and reliably retained in the concavity. Furthermore, if water is sprinkled over an upper portion of the plant, such as leaves, water runs from the leaves along a stem so as to be easily collected into the concavity. Therefore, the water can be easily and reliably retained in the concavity.
9th aspect: the plant cultivation structure according to any one of the 1st to 8th aspects, wherein the water repellent sand layer is formed by the water repellent sand having the surfaces to which water repellent coating is applied, and sand with no water repellent coating mixed thereto.
According to the 9th aspect, effects similar to those of the case of including only the water repellent sand can be achieved also in a case where the water repellent sand layer further is formed by sand with no water repellent coating mixed with the water repellent sand to the surfaces of which water repellent coating is applied.
10th aspect: soil (soil structure) for plant cultivation, comprising:
a water repellent sand layer that is formed by water repellent sand having surfaces to which water repellent coating is applied; and
a plurality of water retaining layers scattered in the water repellent sand layer in a depth direction of the water repellent sand layer and capable of retaining water, wherein
the water retaining layers are in contact with roots of a plant in the water repellent sand layer, the roots grow so as to connect the plurality of water retaining layers, and the water retaining layers retain water that is supplied from outside the water repellent sand layer to the plant and moves along the roots of the plant.
According to the 10th aspect, requisite minimum water can be supplied to plants individually in accordance with the different growth speeds of the respective plants. Furthermore, air can also be supplied to the roots of the plants. As a result, hydroponic culture can be enabled with high efficiency and high quality.
11th aspect: the soil for plant cultivation according to the 10th aspect, wherein the water repellent sand layer is formed by the water repellent sand having the surfaces to which water repellent coating is applied, and sand with no water repellent coating mixed thereinto.
According to the 11th aspect, effects similar to those of the case of including only the water repellent sand can be achieved also in a case where the water repellent sand layer further is formed by sand with no water repellent coating mixed with the water repellent sand to the surfaces of which water repellent coating is applied.
Embodiments of the present invention are described below with reference to the drawings.
In each of
The water repellent sand layer 1 is formed by applying water repellent coating to sand. For example, a portion where the plant 2a is planted is provided with a concavity 1b for supply of water, such that water 31 can be likely retained temporarily (see
The concavity 1b for supply of water may not be formed simply as a concave portion. The concavity 1b may be provided therein with sand capable of retaining water, such as ordinary sand 3Z with no water repellent coating (sand to which water repellent coating is not applied), so as to have a water retentive property (see
The water retaining layers 3 have the water retentive property (in other words, a water absorbing property). The water repellent sand layer 1 is provided therein with the plurality of water retaining layers 3 that are scattered (not mixed) in the depth direction of the water repellent sand layer 1. In
When the roots 2b of the plant 2a grow to reach the water retaining layers 3, the water 31 supplied to the plant 2a in the region facing the outer surface of the water repellent sand layer 1 (such as the ground surface 30) moves in the water repellent sand layer 1 along the surfaces of the roots 2b to reach the water retaining layers 3 as indicated as water supply routes 4, and is retained in the water retaining layers 3. Among the large number of water retaining layers 3, the water retaining layers 3 retaining the water thus moved are painted in black (see reference sign 3A). For example, the water retaining layers 3 can retain the water for about two to three days. The water retained in each of the water retaining layers 3 is absorbed by the root 2b that is in contact with the water retaining layer 3. The roots 2b of the plant 2a are capable of forming the water supply routes 4 because the roots 2b of the plant 2a have hydrophilic surfaces.
In
In
In the configurations shown in
The plant 2a is cultivated, each of the roots 2b also grows to reach another water retaining layer 3, 3B, or 3C that is located below in the depth direction or aside in the horizontal direction. Similarly, water supplied to the ground surface 30 or the like moves along the water supply route 4 of the root 2b so as to be reserved in the water retaining layer 3, 3B, or 3C, and the water thus reserved is absorbed by the root 2b. This cycle is repeated. As a result, as the plant 2a is cultivated, each of the roots 2b contacts with the water retaining layers 3, 3B, or 3C so as to connect the plurality of water retaining layers 3, 3B, or 3C. In this manner, necessary water is reserved in the water retaining layers 3, 3B, or 3C as the roots 2b grow, so that the plant 2a can absorb the water through the roots 2b. In other words, the plant 2a can be cultivated with supply of requisite minimum water (by allowing only an appropriate amount of water necessary for the plant 2a to move from the ground surface 30 to reach the roots 2b by way of the water retaining layers 3, 3B, or 3C). After the supply of water, because the water repellent sand layer 1 has the property of allowing evaporated water to pass therethrough, in the water having flown along the surfaces of the roots 2b, water not retained in the water retaining layers 3, 3B, or 30 but remained on the roots 2b is instantly evaporated and disappeared through the water repellent sand layer 1. Meanwhile, the roots 2b are supplied with air from the region facing the outer surface of the water repellent sand layer 1 through the water repellent sand layer 1. Therefore, necessary air can also be supplied to the roots 2b.
Particularly when the plurality of plants 2a are cultivated, the plants 2a individually grow at different speed in many cases. Also in such a case, the number of the water retaining layers 3, 3B, or 3C in contact with each of the roots 2b is increased as the root 2b grows, and water can be appropriately supplied to the root 2b. Such a feature is remarkably advantageous in practical use.
In a case where the scattered and layered water retaining layers 3C shown in
In conventional hydroponic culture, there have been the following issues. Specifically, relatively to the amount of water and the amount of manure necessary for a plant, water and manure are inefficiently supplied also to a portion of a culture medium where there is no root. Furthermore, water and manure remain excessively around a root of a plant so as to cause insufficient supply of air to the root.
To the contrary, according to the first embodiment, in accordance with the different growth speeds of the respective plants 2a, requisite minimum water or water and manure can be supplied individually to the plants 2a. Furthermore, air can also be supplied to the roots 2b of the plants 2a. As a result, hydroponic culture can be enabled with high efficiency and high quality.
The configuration of the water retaining layers 3B shown in
Similarly to the configuration shown in
Similar effects can be achieved also in a case where the water retaining layers 3, 3B, or 3C preliminarily contain manure.
To the contrary, similar effects are also achieved by adding a manure composition into a water composition to be supplied to the water retaining layers 3, 3B, or 3C. In this case, similar effects are also achieved when each of the water retaining layers 3, 3B, or 3C is configured by ordinary sand with no water repellent coating.
Alternatively, similar effects are achieved also in a case where the water retaining layers 3, 3B, or 3C are configured by ordinary sand containing a water retaining agent.
Still alternatively, similar effects can be achieved by adding a manure composition to the water retaining layers 3, 3B, or 3C. Even if water to be supplied does not contain any manure composition, the water retaining layers 3, 3B, or 3C themselves exert the property of manure when water is supplied thereto.
There is a recent research that a plant is cultivated faster or a grown plant has a higher nutritional value by controlling to appropriately supply minimum water or manure to the plant rather than by supplying sufficient water or manure. For these purposes, it is an important issue to accurately control the amount of water or manure to be supplied in accordance with the growth of the plant. As to such an issue, by applying the first embodiment, water or manure is not excessively supplied to soil around the plant to improve accuracy of quantitative supply of water or manure. In particular, only a necessary amount of water or manure can be supplied to the peripheries of the roots of the plant, so as to easily and accurately control the amount of water or manure to be supplied. According to the first embodiment of the present disclosure, water or manure is not allowed to pass excessively or unlimitedly through the peripheral soil as in the conventional case. Furthermore, after sufficiently supplied along the roots, excessive water or manure does not flow in the soil along the roots, so as to easily detect the necessary amount of supply. As a result, it is possible to control the amount of supply by feedback.
In a case where a chlorosilane-based compound is used as a surface treatment compound for applying water repellent coating to sand, surface treatment can be made with a monomolecular, so that the shapes of the surfaces are not changed by repetition. Therefore, the plant 2a can be cultivated similarly to the case of using ordinary soil.
Described below is preparation of soil for plant cultivation in the configurations shown in
In the case of the water retaining layers 3 having substantially the spherical shapes as shown in
Use of manure is a promising example of the water retaining layers 3 that are capable of retaining water without containing ordinary sand. Most manure has a property as a solid matter by aggregating without water, unlike ordinary sand. If manure is solid and is shaped in aggregates larger than grains, such manure often works slowly as laid manure. In order to prepare soil for plant cultivation, solid manure has only to be added and mixed into water repellent sand. The manure is easily scattered in the water repellent sand layer 1 only by mixing thereinto, so as to prepare the soil for plant cultivation including the water retaining layers 3 having substantially the spherical shapes as shown in
Described next is a test for explaining the basic principle of the plant cultivation structure according to the first embodiment of the present invention.
In
As a result, in the water repellent sand layer 1 having no water permeability, water was proved to move in several minutes. The water repellent sand layer 1 usually has water entry pressure of more than ten cmH2O. Furthermore, as to be described later, even in a case where ordinary sand is mixed into sand with water repellent coating at one third or less, dropped water hardly moves in or enter the water repellent sand layer 1. In six minutes after the drop of water, slight change in color, in other words, arrival of water, was observed in the water retaining layer 3. Then, the portion with change in color was gradually expanded in the water retaining layer 3, and movement of water along the surface of the root 2b into the water retaining layer 3 was observed to the extent that it was clearly checked in about 30 minutes from the start. The test was continued further, and as a result, water 21 having been dropped on the upper surface of the water repellent sand layer 1 was entirely disappeared in about three hours. In consideration of evaporation speed, the entire waterdrop 21 is regarded as having moved to the water retaining layer 3. After four and a half hours from the start, it was checked that the entire region of the water retaining layer 3 having been set was changed in color.
After three days, the water in the water retaining layer 3 was entirely evaporated and disappeared. The water retaining layer 3 was configured by ordinary sand. While water in the liquid form is unlikely to permeate the water repellent sand layer 1, gas like evaporated water is anticipated to easily pass through the water repellent sand layer 1. As having been proved, it is desired to contain a water retaining agent having a polymer material or the like in the water retaining layer 3 for actual plant cultivation, or to configure the water retaining layer 3 so as to prevent evaporation. However, if water around the root 2b is likely to be evaporated in the early stage, air necessary to cultivate the plant 2a can be supplied to the root 2b. Therefore, use of the water repellent sand layer 1 as a culture medium is remarkably effective. There is no concern of root rot or the like. In this test, because the container 20 has the inner wall made of hydrophilic glass, the water possibly moves along the inner wall surface of glass. Therefore, the system is configured such that water does not directly move from/to the water repellent sand layer 1 to/from the inner wall.
As a result, after about 15 minutes from the drop of water, visually checked was that the water permeated, though slightly, to the root 2b in the upper surface 24b of the low water repellent sand layer 1. In two hours later, the amount of water on the low surface was increased enough to form a waterdrop. After six hours from the start of the test, the water 21 on the high surface was entirely disappeared. In this test, because the container has the inner wall made of plastic having no water repellent property, the water possibly moves along the inner wall surface of the plastic container. Therefore, the system is configured such that water does not directly move from/to the water repellent sand layer 1 to/from the inner wall.
It was checked that water could move along the root 2b in the water repellent sand layer 1 without provision of the water retaining layer 3, unlimitedly to vertically downward.
In this case, the states of movement of water along the root 2b in about 15 minutes from the drop of water are similar to the illustrations in
The water repellent sand layer 1 is prepared by applying water repellent coating, with use of a chlorosilane-based fluorine-containing material, to Toyoura sand having an average particle diameter of about 150 μm. The water repellent sand layer 1 has approximately 130 degrees or more of a contact angle measured with pure water. Similar effects can be achieved independently from the type of sand, the particle diameter, or the type of a surface treatment compound. Water repellent coating may be applied with use of a chlorosilane-based material, an alkoxysilane-based material, or the like.
The water repellent sand layer 1 is configured only by water repellent sand to the surfaces of which water repellent coating is applied. However, effects similar to those of the case of including only water repellent sand can be achieved also in a case where sand with no water repellent coating is mixed with water repellent sand at a predetermined mass ratio.
For example, there is a report on a case of varying a mixing rate by mass (%) of water repellent sand obtained by applying water repellent coating to Toyoura sand having an average particle diameter of about 150 μm into sand with no water repellent coating. While water entry pressure (cm) was ˜31.8 cm at the mixing rate by mass of 0%, the water entry pressure was −23.7 cm at the mixing rate by mass of 25%, and the water entry pressure was −13.2 cm at the mixing rate by mass of 50%. The water entry pressure was +7.0 cm at the mixing rate by mass of 75%, and the water entry pressure was +12.0 cm at the mixing rate by mass of 100%. Because ordinary soil absorbs water, the ordinary soil has negative water entry pressure. On the other hand, because water repellent sand does not cause permeation without applying sufficient pressure, the water repellent sand has positive water entry pressure. The water repellent property will be exerted also in a case where sand with no water repellent coating is mixed at a mixing rate by mass of about 25%. Water will be absorbed in a case where sand with no water repellent coating is mixed at the mixing rate by mass of 50%. By approximation of these results, in a case where sand with no water repellent coating is mixed only at a mixing rate by mass of 30 to 350 or less, in other words, in the case where sand with no water repellent coating is mixed at about one third or less of the entire mass, it is possible to configure the water repellent sand layer 1 having the water repellent property. The water repellent sand layer 1 is configured only by water repellent sand to the surfaces of which water repellent coating is applied. However, similar effects can be achieved also in the case where sand with no water repellent coating is mixed at a mass ratio of about one third or less.
The mixing rate by mass is not constant because it is dependent on the water repellent coating material, the amount of coating, the particle diameter of sand, or the like.
In the conventional case shown in
To the contrary, in the case of supply of water according to the aspect of the present invention shown in
Generally, in addition to supply of water or water-based manure, air is essentially supplied to the roots 2b. Because the ordinary sand 26 exerts relatively good drainage, the fact that water is allowed to pass through sand is utilized in many cases. In particular, in a case where sand is used as a culture medium (also called sand culture) in hydroponic culture, water needs to be flown repetitively. Therefore, many inefficient measures are performed such as circulation after filtering. However, in the first embodiment of the present invention, only a requisite minimum amount of water is supplied, and also air can be very smoothly supplied to the roots 2b through the water repellent sand layer 1. These features are regarded as quite advantageous.
Because the garlic plants 5a do not prefer acid soil, magnesium lime is entirely dispersed on the portions to planted the garlic plants prior to cultivation in many cases. Also in the test illustrated in
By properly combining the arbitrary embodiment(s) or modification(s) of the aforementioned various embodiments and modifications, the effects possessed by the embodiment(s) or modification(s) can be produced.
The present invention has been described in connection with the various embodiments and modifications thereof. It is certain that the present invention shall not be limited to such various embodiments and modifications.
The plant cultivation structure and the soil for plant cultivation according to the aspect of the present invention each include the water repellent sand obtained by applying water repellent coating to sand, the plant that is cultivated by growing roots in the water repellent sand, and the plurality of water retaining layers scattered (not mixed) in the water repellent sand, so that each of the roots grows to reach at least one of the water retaining layers. In this configuration, water and manure supplied to the plant in the region facing the outer surface of the water repellent sand move along the roots in the water repellent sand and reach the water retaining layers. Therefore, necessary water and manure are reserved in the water retaining layers in accordance with the growth of the roots, so that the plant can absorb the reserved water and manure through the roots. As a result, the plants can be cultivated with supply of requisite minimum water and manure to the plants individually in accordance with the different growth speeds of the respective plants. Furthermore, air is supplied from the water repellent sand to the peripheries of the roots while the water and the manure do not move. Therefore, the plant cultivation structure and the soil for plant cultivation are usefully applied. The plant cultivation structure and the soil for plant cultivation according to the aspect of the present invention are capable of supplying requisite minimum water and manure to any plant having growing roots, as well as are capable of supplying air to the roots of the plant.
The entire disclosure of Japanese Patent Application No. 2011-122999 filed on Jun. 1, 2011, including specification, claims, drawings, and summary are incorporated herein by reference in its entirety.
Although the present invention has been fully described in connection with the embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.
Number | Date | Country | Kind |
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2011-122999 | Jun 2011 | JP | national |
2012-010363 | Jan 2012 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2012/003369 | May 2012 | US |
Child | 13790371 | US |