JP6231805B2 - Artificial soil particles and plant growth medium - Google Patents

Description

  The present invention relates to artificial soil particles for plant growth and a plant growth medium using the artificial soil particles.

  In recent years, plant factories that grow plants such as vegetables in an environment where growth conditions are controlled are increasing. Until now, plant factories have mainly focused on hydroponics of leafy vegetables such as lettuce, but recently, root vegetables that are not suitable for hydroponics have also been tried.

  When cultivating root vegetables using natural soil in a plant factory, since there is a problem of bringing in pests to the plant factory, there is a movement to cultivate root vegetables and the like using artificial soil. In the cultivation of root vegetables, it is necessary to maintain the soil in a hydrogen ion concentration (pH) region that is optimal for the growth of root vegetables. However, since artificial soil generally has less pH buffering action than natural soil, the pH of artificial soil may change due to root acid or the like secreted by plants. As a result, the fertilizer component retained in the soil may flow out, or the growth of the plant may be disturbed. For this reason, when cultivating a plant using artificial soil, it is necessary to manage pH in soil appropriately.

  As a technique related to pH adjustment of artificial soil developed so far, cultured soil using a soil improving material containing a pH adjuster is known (see, for example, Patent Document 1).

JP 2003-38027 A

  The technique of adjusting the pH of the soil of patent document 1 adds a pH adjuster to the culture soil containing natural soil, and raises the pH buffer capacity of soil. However, even if this technology is directly applied to cultivation of a plant body using artificial soil, the pH of the artificial soil cannot always be maintained sufficiently. Patent Document 1 merely increases the pH buffering capacity of the soil, and in order to appropriately manage the pH of the artificial soil, it is necessary to monitor the pH of the artificial soil over time.

  The present invention has been made in view of the above problems, and uses artificial soil particles that can easily determine and manage changes in the pH of a plant growth medium for growing plants, and the artificial soil particles. An object is to provide a plant growth medium.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
Artificial soil particles containing a pH indicator that changes color according to the hydrogen ion concentration ,
The pH indicator includes a plurality of types of pH indicators, and each pH indicator is combined so as to exhibit the same hue in a region where the hydrogen ion concentration is 5 to 7.5 .

According to the artificial soil particle of this structure, since the pH indicator which changes color according to a hydrogen ion concentration is contained, the change of pH of the plant growth medium comprised from an artificial soil particle can be judged visually. Accordingly, the pH of the plant growth medium can be appropriately managed, and the pH of the plant growth medium can be easily adjusted to an optimum pH for growing the cultivated plant while visually confirming. Furthermore, when cultivating foliage plants indoors, when the plant growth medium is placed in a transparent pot etc., the color of the artificial soil particles changes according to the change in pH, so the plant growth medium also has excellent interior properties It can be.
Here, the pH indicator includes a plurality of types of pH indicators, and each pH indicator is combined so as to exhibit the same hue in the region where the hydrogen ion concentration is 5 to 7.5. The hue at is emphasized. Therefore, since the difference in hue between the pH range of 5 to 7.5 and the other pH ranges is clarified, the change in pH of the plant growth medium near neutral, which is particularly important for plant growth, can be more reliably confirmed. It can be judged visually. As a result, it is possible to more reliably manage and adjust the pH of the plant growth medium.

In the artificial soil particles according to the present invention,
Said plurality of kinds of pH indication agents, combination of the Congo red and neutral red, be at least one selected from the combinations of the combination of methyl red and bromothymol blue, or methyl red and cresol red preferable.

According to the artificial soil particles of this configuration, as a plurality of kinds of pH indication agents, combination of the Congo red and neutral red, a combination of methyl red and bromothymol blue, or in a combination of methyl red and cresol red Therefore, red or yellow is emphasized in the region where the pH near neutral is 6-7. Accordingly, since the difference in hue between the pH range of 6 to 7 and the other pH range is further clarified, the change in pH of the plant growth medium can be more reliably judged visually. As a result, the pH of the plant growth medium can be more appropriately managed and adjusted.

In the artificial soil particles according to the present invention,
A base portion formed by collecting a plurality of fillers having pores so that a communication hole is formed between the fillers, and the pH indicator is carried at least in a region extending from the inside of the communication hole to the surface of the base portion. Preferably there is.

  According to the artificial soil particle of this configuration, since the above structure is provided, when water is held in the communication hole, the pH indicator carried in the region extending from the inside of the communication hole to the surface of the base is dissolved in the water, and the plant The change in color associated with the change in pH of the growth medium is reflected. As a result, the pH of the plant growth medium can be properly managed, and the pH of the plant growth medium can be adjusted to an optimum state for the growth of the cultivated plant while visually confirming.

In the artificial soil particles according to the present invention,
It is preferable that ion exchange capacity is imparted to the pores.

  According to the artificial soil particle of this structure, since the ion exchange ability is provided to the pore, the fertilizer can be carried on the artificial soil particle. Artificial soil particles imparted with ion exchange ability can carry or release fertilizer components by changing the pH of the plant growth medium. Since the artificial soil particles of this configuration can recognize the pH of the plant growth medium by a color change, the artificial soil particles are supported on the artificial soil particles by adjusting the pH while visually checking the pH of the plant growth medium. It is possible to effectively release the fertilizer that has been used at the optimal time for the growth of cultivated plants.

In the artificial soil particles according to the present invention,
It is preferable that a base portion in which fibers are gathered and a coating layer covering the base portion are provided, and at least the pH indicator is supported on the coating layer.

  According to the artificial soil particle of this configuration, since the above structure is provided, when the moisture of the plant growth medium is absorbed by the base, the pH indicator dissolves in the moisture passing through the coating layer, and the pH of the plant growth medium changes. The color change that accompanies is reflected. As a result, the pH of the plant growth medium can be properly managed, and the pH of the plant growth medium can be adjusted to an optimum state for the growth of the cultivated plant while visually confirming.

The characteristic configuration of the plant growth medium according to the present invention for solving the above problems is as follows:
The use of any one of the above artificial soil particles.

  According to the plant growth medium using the artificial soil particles of this configuration, since it is composed of artificial soil particles containing a pH indicator that changes color according to the hydrogen ion concentration, according to the change in pH of the plant growth medium The color of the artificial soil particles changes. For this reason, the change of pH of a plant growth medium can be judged visually. As a result, the pH of the plant growth medium can be appropriately managed, and the pH of the plant growth medium can be adjusted to an optimum pH for the growth of the cultivated plant while visually confirming.

FIG. 1 is an explanatory diagram conceptually showing two types of artificial soil particles. FIG. 2 is an explanatory view conceptually showing artificial soil particles formed by gathering fillers.

  Hereinafter, the embodiment regarding the artificial soil particle which concerns on this invention, and the plant growth culture medium using the said artificial soil particle is described based on FIG.1 and FIG.2. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Artificial soil particles>
FIG. 1 is an explanatory view conceptually showing two types of artificial soil particles 50 according to an embodiment of the present invention. FIG. 1A illustrates an artificial soil particle 50a in which a plurality of fillers 1 are aggregated to form a granular material (base), and a pH indicator 2 is carried between the fillers 1. FIG. 1B illustrates an artificial soil particle 50b that forms a fiber lump 10 (base) in which fibers 3 are aggregated, and that has a coating layer 20 containing a pH indicator 2 on the outer surface of the fiber lump 10. It is a thing. Since the pH indicator 2 carried on these artificial soil particles 50 changes color in response to the hydrogen ion concentration of water that has entered the artificial soil particles 50, the pH of the plant growth medium using the artificial soil particles 50 is visually checked. Can be easily determined. Therefore, when a pH adjusting agent or the like is added to the plant growth medium, the pH of the plant growth medium can be adjusted to an optimum pH for the growth of the cultivated plant while visually confirming. In addition, when the artificial soil particles 50 of the present invention are put in a transparent pot or the like and a houseplant is grown indoors, the color of the artificial soil particles 50 changes according to the change in pH, and the plant grows with excellent interior properties. It becomes a medium. The plant growth medium should just be a form which can grow a plant using the artificial soil particle 50. FIG. For example, the artificial soil particles 50 may be simply used instead of natural soil, or the artificial soil particles 50 may be formed into a sheet by solidifying with a binder, or the artificial soil particles 50 may be solidified with a binder or the like to form a block. It may be formed.

  The pH indicator 2 used in the present invention is not limited as long as it can distinguish between a pH region where a plant to be grown can grow and a pH region which may adversely affect the growth of the plant. pH indicator 2 is cochineal red, lac dye, anthocyanin red dye, congo red, litmus, phenol red, neutral red, naphthol red, methyl red, cresol red, bromocresol purple, bromocresol green, methyl orange, methyl yellow, Examples include thymol blue, naphtholphthalein, phenolphthalein, thymolphthalein, and bromothymol blue, preferably cochineal red, lac dye, anthocyanin red dye, Congo red, neutral red, methyl red, cresol red, bromocresol. Purple, bromothymol blue.

  The color change range of cochineal red is orange at pH 4 or less, red at pH 5 to 7.5, and reddish purple at pH 8 or more. The color change range of the rack dye is orange at pH 4 or less, reddish orange at pH 5 to 7.5, and reddish purple at pH 8 or more. The discoloration range of the anthocyanin-based red pigment is pH 4 or less, red to magenta, pH 5.5 to 7 is light purple, pH 8 or more is blue violet. The color change range of Congo red is purple at pH 3 or lower, and red at pH 5 or higher. The neutral red color change range is red at pH 7 or less and yellow at pH 8 or more. The color change range of methyl red is red at pH 4.4 or less and yellow at pH 6.2 or more. The color change range of cresol red is yellow at pH 7.2 or lower, and reddish purple at pH 8.8 or higher. The discoloration range of bromocresol purple is yellow at pH 5 or lower and purple at pH 7 or higher. The color change range of bromothymol blue is yellow at pH 6 or less and blue at pH 7.6 or more.

  The content of the pH indicator 2 with respect to the artificial soil particles 50 is preferably 0.1 to 75% by weight. When the content of the pH indicator 2 is less than 0.1% by weight, the artificial soil particles 50 may not be sufficiently colored and the change in pH of the plant growth medium may not be confirmed. Further, even if the artificial soil particles 50 contain more than 75% by weight of the pH indicator 2, there is no significant difference in the color change of the artificial soil particles 50, which is economically disadvantageous.

  The pH indicator 2 may be contained alone in the artificial soil particles 50, or a plurality of pH indicators 2 may be combined and contained in the artificial soil particles 50. When a plurality of pH indicators 2 are contained in the artificial soil particles 50, the color of the artificial soil particles 50 can be clearly changed according to the change in pH of the plant growth medium. Thereby, the pH of a plant growth culture medium can be judged reliably visually. The combination of the pH indicator 2 is preferably combined so as to exhibit the same hue in the region of pH 5 to 7.5 optimum for the cultivation of many plants. By combining a plurality of pH indicators 2 that exhibit the same hue in the pH range of 5 to 7.5, the hue of the artificial soil particles 50 at pH 5 to 7.5 is emphasized. As a result, a difference in hue from a pH region other than pH 5 to 7.5 becomes clear, and it becomes possible to more reliably visually determine a change in the pH of the plant growth medium.

  Specific combinations of pH indicators 2 include, for example, a combination of Congo red and neutral red, a combination of methyl red and bromothymol blue, or a combination of methyl red and cresol red. The combination of Congo Red and Neutral Red highlights red in the pH 5-7 region, and the combination of methyl red and bromothymol blue highlights yellow in the pH 5-7 region. The combination is highlighted in yellow in the pH 6-7 region. Changes in the color of the plant growth medium due to the combination of Congo Red and Neutral Red change to purple at pH 3 or lower, red at pH 5-7, yellow at pH 8 or higher, and plant due to the combination of methyl red and bromothymol blue The change in the color of the growth medium is red at pH 4 or less, yellow in the region of pH 5 to 7, and blue-green at pH 8 or more. The change in the color of the plant growth medium by the combination of methyl red and cresol red is pH 4 or less. At red, yellow at pH 6-7, reddish purple at pH 9 or higher. By such a combination, the hue of a specific pH region is emphasized and can be clearly distinguished from the hues of other pH regions.

  The combination of a plurality of pH indicators 2 may be a combination of pH indicators 2 that exhibit the same hue in a pH range optimal for the growth of a specific plant. When the plant to be cultivated is a vegetable, for example, carrots, cucumbers, onions, sweet potatoes, pumpkins and the like may be combined with a pH indicator 2 that exhibits the same hue in the pH 5.5-7 region (for example, Congo Red and Neutral Red). ), Radish, spinach, asparagus, and the like may be combined with pH indicator 2 that exhibits the same hue in the pH range of 6 to 7.5 (for example, a combination of methyl red and cresol red). When the plant to be cultivated is a flower bud, for example, rose, hydrangea (red), tulip, marigold, carnation and the like may be combined with pH indicator 2 exhibiting the same hue in the pH 6 to 7 region, and orchid, begonia and the like have pH 5 What is necessary is just to combine the pH indicator 2 which exhibits the same hue in the area | region of -6. When the plant to be cultivated is a foliage plant, for example, ivy, aloe, dracaena, benjamin, pothos and the like may be combined with pH indicator 2 exhibiting the same hue in the region of pH 5.5 to 6.5, anthrum, table palm, Peperomia and the like may be combined with a pH indicator 2 that exhibits the same hue in a pH range of 5 to 6.5.

<Structure of granular material>
FIG. 2 is an explanatory diagram conceptually showing the artificial soil particles 50 a formed by assembling the fillers 1. The artificial soil particle 50a is obtained by assembling a plurality of fillers 1 into a granular material (base). FIG. 2A illustrates an artificial soil particle 50 a using a zeolite 1 a that is a porous natural mineral as the filler 1. FIG. 2B illustrates an artificial soil particle 50 a using a hydrotalcite 1 b that is a layered natural mineral as the filler 1.

  It is not essential that the fillers 1 in the artificial soil particles 50a are in contact with each other, and if the relative positional relationship within a certain range is maintained through a binder or the like in one particle, It can be considered that a plurality of fillers 1 are aggregated to form a granular shape. The filler 1 constituting the artificial soil particle 50a has a large number of pores 4 from the surface to the inside. The pore 4 includes various forms. For example, when the filler 1 is the zeolite 1a shown in FIG. 2A, the voids present in the crystal structure of the zeolite 1a are the pores 4a, and the hydrotalcite 1b shown in FIG. The interlayer existing in the layer structure of the hydrotalcite 1b is the pore 4b. That is, in the present invention, “pores” mean voids, interlayers, spaces, etc. existing in the structure of the filler 1, and these are not limited to “pore-like” forms. Since the zeolite 1a and the hydrotalcite 1b are ion-exchangeable minerals, the fertilizer component can be held in the pores 4.

  In the artificial soil particles 50 a, communication holes 5 are formed between the plurality of fillers 1. The pH indicator 2 is carried in a region extending from the inside of the communication hole 5 to the surface of the base. The communication hole 5 can mainly retain moisture, and can efficiently take in moisture contained in the plant growth medium. Thereby, the pH indicator 2 contained in the artificial soil particle 50a can be efficiently discolored according to the change in pH in the plant growth medium. As a result, a change in pH of the plant growth medium can be reliably determined visually.

  The filler 1 used in the artificial soil particle 50a of the present invention includes, for example, inorganic minerals such as pearlite, talc, diatomaceous earth, kaolin, rock wool, and ion-exchange mineral, peat moss, urethane foam, coconut shell, Cryptomos (registered trademark), and cellulose. Examples thereof include organic materials such as fibers. Among these, the ion-exchange mineral is preferably used because it imparts sufficient fertilizer to the artificial soil particles 50a. Examples of the ion exchange mineral include a cation exchange mineral, an anion exchange mineral, and humus. Further, in order to provide fertilizer to the artificial soil particles 50a, a porous material (for example, a polymer foam, a glass foam, etc.) having no ion exchange ability is separately prepared, and the pores of the porous material It is also possible to introduce a material imparted with ion exchange capacity into the material by press-fitting or impregnation and use it as the filler 1. It is also possible to introduce an ion exchange resin.

  The fertilizing ability of the artificial soil particles 50a using the ion exchange mineral or the like is greatly affected by the change in pH of the plant growth medium. If the pH of the plant growth medium changes, the fertilizer component adsorbed on the ion exchanger may flow out, and the artificial soil particles 50a may not be able to hold the fertilizer component. In order to avoid this, it is necessary to maintain the pH of the plant growth medium in a pH region where the fertilizer of the artificial soil particles 50a can be held. Since the artificial soil particles 50a contain the pH indicator 2, the pH of the plant growth medium can be easily determined visually. Therefore, by adding a pH adjuster or the like to the plant growth medium, the pH of the plant growth medium can be reliably adjusted to a pH at which the fertilizer can be retained while visually checking. In addition, by adding citric acid, which is the main component of root acid, to the plant growth medium and adjusting the pH of the plant growth medium visually, it is necessary for the growth of the plant according to the growth of the cultivated plant. It is also possible to elute the fertilizer component at a predetermined time.

  Examples of cation exchange minerals include smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, and zeolite. Examples of the cation exchange resin include a weak acid cation exchange resin and a strong acid cation exchange resin. Of these, zeolite or bentonite is preferable. The cation exchange mineral and the cation exchange resin can be used in combination of two or more. The cation exchange capacity of the cation exchange mineral and the cation exchange resin is set to 10 to 700 meq / 100 g, preferably 20 to 700 meq / 100 g, and more preferably 30 to 700 meq / 100 g. When the cation exchange capacity is less than 10 meq / 100 g, the nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the cation exchange capacity exceeds 700 meq / 100 g, the effect is not greatly improved and it is not economical.

  Anion-exchange minerals include, for example, natural layered double hydroxides that have double hydroxides as the main skeleton such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, synthetic hydrotalcite and hydrotalcite-like Materials, clay minerals such as allophane, imogolite, kaolin and the like. Examples of the anion exchange resin include weakly basic anion exchange resins and strong basic anion exchange resins. Of these, hydrotalcite is preferred. An anion exchange mineral and an anion exchange resin can be used in combination of two or more. The anion exchange capacity of the anion exchange mineral and the anion exchange resin is set to 5 to 500 meq / 100 g, preferably 20 to 500 meq / 100 g, and more preferably 30 to 500 meq / 100 g. When the anion exchange capacity is less than 5 meq / 100 g, the nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the anion exchange capacity exceeds 500 meq / 100 g, the effect is not greatly improved and it is not economical.

<Filler granulation method>
In forming the artificial soil particles 50a, granulation can be performed using a binder in order to collect a plurality of fillers 1 to form a granular material (artificial soil particles 50a). The formation of artificial soil particles 50a using a binder is performed by adding a binder or a solvent to the filler 1 and the pH indicator 2 and mixing them, introducing the mixture into a granulator, rolling granulation, fluidized bed granulation, stirring granulation. It can be performed by a known granulation method such as granulation, compression granulation, extrusion granulation, crush granulation, melt granulation, spray granulation or the like. The obtained granular material is dried and classified as necessary to complete the artificial soil particle 50a. Thereby, the artificial soil particle 50a in which the filler 1 and the pH indicator 2 are uniformly dispersed can be obtained. In addition, a binder is added to the filler 1 and the pH indicator 2, and a solvent is added and kneaded as necessary. The resulting mixture is dried and then crushed into a mortar and pestle, hammer mill, roll crusher, etc. It is also possible to obtain a granular material by appropriately pulverizing by means. This granular material can be used as the artificial soil particle 50a as it is, but it is preferable to adjust to a desired particle size by sieving. Since the artificial soil particles 50a contain a pH indicator, it is preferable to use a neutral or neutralized pH of the material such as filler 1 and binder used. Thereby, the change of the color of the artificial soil particle 50a by pH change becomes clear. The artificial soil particles 50a may be provided with a coating layer to be described later. Thereby, it becomes possible to further control the water retention and fertilizer retention of the artificial soil particles 50a.

  As a binder for granulating the artificial soil particles 50a, either an organic binder or an inorganic binder can be used. Organic binders include, for example, polyolefin binders, polyvinyl alcohol binders, polyurethane binders, vinyl acetate binders such as vinyl acetate and ethylene vinyl acetate, urethane resin binders such as urethane resins and vinyl urethane resins, acrylic resin binders, Examples include synthetic resin binders such as silicone resin binders; polysaccharides such as starch, carrageenan, xanthan gum, gellan gum, and alginates, and natural product binders such as proteins such as polyamino acids and glues. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more. Since the artificial soil particles 50a contain a pH indicator that changes color according to the hydrogen ion concentration, the binder used is preferably a colorless or white binder. Thereby, the change of the color of the artificial soil particle 50a by pH change becomes clear.

  In forming the artificial soil particles 50a, the artificial soil particles 50a can be granulated using a gelation reaction of a polymer gelling agent. Examples of the gelation reaction of the polymer gelling agent include gelation reaction between alginate and polyvalent metal ions, gelation reaction of carboxymethylcellulose (CMC), and gel formed by double helical structure reaction of polysaccharides such as carrageenan. Reaction. Among these, the gelation reaction between an alginate and a polyvalent metal ion will be described. Sodium alginate, which is one of alginates, is a neutral salt in which the carboxyl group of alginic acid is bonded to Na ions. Alginic acid is not required in water, but sodium alginate is water soluble. When an aqueous sodium alginate solution is added to an aqueous solution of polyvalent metal ions (for example, Ca ions), ionic crosslinking occurs between the molecules of sodium alginate and gelation occurs. In the case of this embodiment, the gelation reaction can be performed by the following steps. First, an alginate aqueous solution is prepared by dissolving alginate in water, filler 1 and pH indicator 2 are added to the alginate aqueous solution, this is sufficiently stirred, and filler 1 and pH indicator 2 are added to the alginate aqueous solution. Forms a mixed liquid. Next, the mixed solution is dropped into the polyvalent metal ion aqueous solution, and the alginate contained in the mixed solution is gelled in a granular form. Filler 1 and pH indicator 2 are incorporated into this gel. Thereafter, the gelled particles are collected, washed with water, and sufficiently dried. Thereby, the granular material which the filler 1 and the pH indicator 2 disperse | distributed in the alginic acid gel formed from an alginate and a polyvalent metal ion is obtained. The granular material is dried and classified as necessary to obtain artificial soil particles 50a. The preferable particle diameter of the artificial soil particles 50a is in the range of 0.2 to 10 mm.

  Examples of alginates that can be used in the gelation reaction include sodium alginate, potassium alginate, and ammonium alginate. These alginate can be used in combination of two or more. The concentration of the alginate aqueous solution is 0.1 to 5% by weight, preferably 0.2 to 5% by weight, and more preferably 0.2 to 3% by weight. When the concentration of the alginate aqueous solution is less than 0.1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 5% by weight, the viscosity of the alginate aqueous solution becomes too large. Therefore, the filler 1 and the pH indicator 2 were added. It becomes difficult to stir the mixed solution and to drop the mixed solution into the aqueous polyvalent metal ion solution.

  The polyvalent metal ion aqueous solution to which the alginate aqueous solution is dropped may be a divalent or higher valent metal ion aqueous solution that reacts with the alginate and gels. Examples of such polyvalent metal ion aqueous solutions include aqueous chloride solutions of polyvalent metals such as calcium chloride, barium chloride, strontium chloride, nickel chloride, aluminum chloride, iron chloride, cobalt chloride, calcium nitrate, barium nitrate, aluminum nitrate. Nitrate aqueous solutions of polyvalent metals such as iron nitrate, copper nitrate and cobalt nitrate, lactate aqueous solutions of polyvalent metals such as calcium lactate, barium lactate, aluminum lactate and zinc lactate, aluminum sulfate, zinc sulfate, cobalt sulfate etc. An aqueous solution of a valent metal sulfate is mentioned. These polyvalent metal ion aqueous solutions can be used in combination of two or more. The concentration of the polyvalent metal ion aqueous solution is 1 to 20% by weight, preferably 2 to 15% by weight, and more preferably 3 to 10% by weight. When the concentration of the polyvalent metal ion aqueous solution is less than 1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 20% by weight, it takes time to dissolve the metal salt and excessive materials are used. Not economical.

<Structure of fiber lump>
In the artificial soil particle 50b, the fiber lump 10 (base) in which the fibers 3 are aggregated may be used as the artificial soil particle 50b, or the covering layer 20 is formed on the fiber lump 10 as shown in FIG. Also good. By providing the coating layer 20, it is possible to control the absorption and release of moisture of the fiber lump 10 more precisely.

  The fiber lump 10 is configured as an aggregate of fibers 3. Gaps 6 are formed between the fibers 3 constituting the fiber lump 10. The fiber lump 10 can retain moisture in the gap 6. Therefore, the state of the void 6 is related to the water retention of the fiber mass 10. The state of the gap 6 can be adjusted by changing the amount (density) of the fibers 3 used when forming the fiber lump 10, the type, thickness, length, and the like of the fibers 3. In addition, the size of the fiber 3 is preferably 5 to 100 μm in thickness, and preferably 0.5 to 10 mm in length.

  Since the fiber lump 10 is configured so that moisture can be retained therein, it is preferable to use a hydrophilic fiber as the fiber 3. The type of the fiber 3 may be either natural fiber or synthetic fiber, and is appropriately selected according to the type of the artificial soil particle 50b. Examples of preferable hydrophilic fibers include cotton, wool, and rayon as natural fibers, and examples of synthetic fibers include vinylon, urethane, nylon, and acetate. Of these, cotton and vinylon are more preferable. What mixed the natural fiber and the synthetic fiber may be used. Since the artificial soil particles 50b contain a pH indicator that changes color according to the hydrogen ion concentration, the fibers used are preferably colorless or white fibers. Thereby, the change of the color of the artificial soil particle 50b by pH change becomes clear.

<Method for forming fiber lump>
The fiber lump 10 is formed by a known granulation method. For example, the fibers 3 are aligned with a carding apparatus or the like, cut to a length of about 3 to 10 mm, and the cut fibers 3 are subjected to rolling granulation, fluidized bed granulation, stirring granulation, compression granulation, extrusion granulation. It can form by granulating by methods, such as. During granulation, the fiber 3 may be mixed with a binder such as resin or glue, but the fibers 3 are entangled with each other and easily fixed, so that the fibers 3 can be agglomerated without using a binder. Can be processed. The pH indicator 2 may be mixed when the fiber lump 10 is granulated. When the coating layer 20 is formed on the outer surface of the fiber lump 10, the pH indicator 2 is contained in the covering layer 20 to be included in the fiber lump 10. 10 may not be mixed. Since the artificial soil particle 50b contains a pH indicator, it is preferable to use a neutral or neutralized pH of the material such as the fiber 3 to be used. Thereby, the change of the color of the artificial soil particle 50b by pH change becomes clear.

  In granulating the fiber lump 10, it is possible to use short fibers as the fibers 3. In this case, the resin emulsion is added in small amounts and granulated while stirring the short fibers with a stirring and mixing granulator. As a result, the short fibers forming the fiber lump 10 are partially fixed and a strong fiber lump 10 can be formed.

<Method for forming coating layer>
As shown in FIG. 1 (b), a coating layer 20 can be formed on the outer surface of the fiber lump 10. The covering layer 20 is preferably formed of a material having good water permeability. When the pH indicator 2 is contained in the coating layer 20, the color of the artificial soil particles 50 can be reliably changed according to the change in the pH of water present in the plant growth medium. Moreover, the covering layer 20 can control not only the responsiveness of the pH indicator 2 but also the release of the fertilizer component carried on the artificial soil particles 50 by selecting the material.

  Examples of a method for forming the coating layer 20 include an impregnation method described below. The fiber lump 10 illustrated in the item of “Method of forming a fiber lump” described above is put into a container, and about half of the volume (occupied volume) of the fiber lump 10 is added to the fiber lump 10, and water is added to the fiber lump 10. Let it soak. Next, a resin emulsion for coating containing the pH indicator 2 of 1/3 to 1/2 of the volume of the fiber lump 10 is added to the fiber lump 10 soaked with water. Next, the resin emulsion is impregnated from the outer surface portion of the fiber lump 10 while rolling so that the resin emulsion uniformly adheres to the outer surface portion of the fiber lump 10. At this time, since the water has soaked into the central portion of the fiber lump 10, the resin emulsion remains near the outer surface of the fiber lump 10. Thereafter, the fiber lump 10 to which the resin emulsion is adhered is dried in an oven, the resin is then melted, and the resin is fused to the fibers 3 near the outer surface of the fiber lump 10 to form a resin coating as the coating layer 20. Form. Thereby, the artificial soil particle 50b by which the outer surface of the fiber lump 10 was covered with the coating layer 20 containing the pH indicator 2 is completed. The covering layer 20 has a thickness that is slightly infiltrated inward from the outer surface portion of the fiber lump 10 so as to reinforce the entangled portions of the fibers 3 constituting the fiber lump 10 (portions where the fibers 3 are in contact with each other). It may be formed. Thereby, the intensity | strength and durability of the artificial soil particle 50b can be improved. The film thickness of the coating layer 20 is set to 1 to 200 μm, preferably set to 10 to 100 μm, and more preferably set to 20 to 60 μm. In this method, the characteristics of the coating layer 20 formed on the outer surface of the fiber lump 10 can be changed by adjusting the type and concentration of the resin in the resin solution to be impregnated.

  The material of the covering layer 20 is preferably insoluble in water and hardly oxidized, and examples thereof include a resin material. Examples of such a resin material include polyolefin resins such as polyethylene and polypropylene, vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, polyester resins such as polyethylene terephthalate, and styrene resins such as polystyrene. Of these, polyethylene is preferred. In place of the resin material, a synthetic polymer gelling agent such as polyethylene glycol or a natural gelling agent such as sodium alginate can be used. Since the artificial soil particles 50 contain a pH indicator that changes color according to the hydrogen ion concentration, the material of the coating layer 20 used is preferably colorless or white. Thereby, the change of the color of the artificial soil particle 50 by pH change becomes clear.

<Artificial soil aggregate>
The artificial soil particle 50 of the present invention can be further aggregated and used as a plant growth medium in the form of an artificial soil aggregate.

  The artificial soil aggregate has a cluster structure in which a plurality of artificial soil particles 50 are connected. A cluster structure is obtained by bonding a plurality of artificial soil particles 50 with a secondary binder. The pH indicator 2 may be included in the artificial soil particles 50, but may be added when the artificial soil aggregate is formed with a secondary binder. The secondary binder used for the aggregation of the artificial soil particles 50 can be the same as the binder used in the formation of the artificial soil particles 50, but may be a different type of binder. The size of the artificial soil aggregate is 0.4 to 20 mm, preferably 0.5 to 18 mm, more preferably 1 to 15 mm, and most preferably 2 to 4 mm. When the size of the artificial soil aggregate 100 is less than 0.4 mm, the gap between the artificial soil particles 50 constituting the artificial soil aggregate is reduced and the drainage performance is reduced. May be difficult to absorb. On the other hand, if the size of the artificial soil aggregate exceeds 20 mm, the drainage property becomes excessive and the plant becomes difficult to absorb moisture, or the artificial soil aggregate is sparse and the plant may fall over. There is.

  The test which evaluates the discoloration property by pH was implemented about the plant growth culture medium using the artificial soil particle | grains of this invention.

<Production of artificial soil particles and artificial soil aggregates>
According to the composition (parts by weight) described in Table 1 and Table 2 below, talc (SW, manufactured by Nippon Talc Co., Ltd.), cellulose fiber (Avocel B800, manufactured by Showa Chemical Industry Co., Ltd.), diatomaceous earth (Radiolite ( (Registered trademark) F, manufactured by Showa Chemical Industry Co., Ltd.), vinylon fiber (VF1203-2, manufactured by Kuraray Co., Ltd.), cation exchange mineral zeolite (Ryukyu Light CEC600, manufactured by Ecowell Co., Ltd.), and anion exchange Artificial soil of Examples 1 to 22 and Comparative Examples 1 and 2 in which at least one of hydrotalcite (manufactured by Wako Pure Chemical Industries, Ltd.), which is a mineral, is mixed with a pH indicator and the mixture is solidified with a binder. Particles were made. As the binder, sodium alginate (manufactured by Wako Pure Chemical Industries, Ltd.) or polyethylene mixed emulsion solution (Sepoljon (registered trademark) G315, manufactured by Sumitomo Seika Co., Ltd.) was used. When using sodium alginate, a filler and a pH indicator are added to a 0.5% aqueous solution of sodium alginate and stirred for 3 minutes using a mixer (SM-L57: manufactured by Sanyo Electric Co., Ltd.). Then, it was dropped into a 5% calcium chloride aqueous solution, which is an aqueous polyvalent metal ion solution, to form a gelled product. The produced gelled product was collected from the liquid, washed, and then dried in a dryer at 55 ° C. for 24 hours to produce artificial soil particles. When using a polyethylene mixed emulsion solution, a filler and a pH indicator were mixed with stirring in a 20% polyethylene mixed emulsion solution, and the granulated product was classified by sieving to produce artificial soil particles. For Example 7, Example 8, Example 12, Example 13, Example 14, Example 20, Example 21, and Example 22, 100 parts by weight of the obtained artificial soil particle single particles, As a secondary binder, 5 parts by weight of a vinyl acetate resin adhesive “Bond (registered trademark) woodworking” manufactured by Konishi Co., Ltd. is mixed as a secondary binder, and the mixture is introduced into a granulator to be agglomerated to form an artificial soil aggregate. Was made.

  Examples of pH indicators include cochineal red (Carmine Red MK-40, manufactured by Kiriya Chemical Co., Ltd.), rack dye (Rakkin Red R, manufactured by Kiriya Chemical Co., Ltd.), anthocyanin red dye (Kiriya Red RC-Y, Kiriya Chemical Co., Ltd.) Company), Congo Red (Wako Pure Chemical Industries, Ltd.), Neutral Red (Wako Pure Chemical Industries, Ltd.), Methyl Red (Wako Pure Chemical Industries, Ltd.), Cresol Red (Wako Pure Chemical Industries, Ltd.) ), Bromocresol purple (manufactured by Wako Pure Chemical Industries, Ltd.), and bromothymol blue (manufactured by Wako Pure Chemical Industries, Ltd.) were used. For Comparative Examples 1 and 2, artificial soil particles containing Benikouji pigment (Monasco Red AL, manufactured by Kiriya Chemical Co., Ltd.) used for food coloring and the like were used.

<Test content>
(1) Discoloration due to pH of plant growth medium: Each of the artificial soil particles prepared above (Examples 1 to 22, Comparative Examples 1 and 2) was impregnated in an aqueous solution adjusted in pH. The discoloration due to pH of each artificial soil particle was visually observed. The color change due to pH was shown in the range of hues based on the Munsell color chart. The Munsell color chart will be described below.
The hue of the artificial soil particles by the pH indicator can be expressed by a color system based on the Munsell color chart. The Munsell color system is a type of system (color system) that expresses colors based on the three attributes of color. The Munsell color system is standardized as JIS Z 8721 (color display method using three attributes). Here, the three attributes mean three of hue, lightness, and saturation, and “hue” among the three attributes represents the type of color. The hues are five basic colors of red (R), yellow (Y), green (G), blue (B) and purple (P), and yellow, red (YR) and yellow-green (GY), which are intermediate colors. ), Blue-green (BG), blue-violet (PB) and red-purple (RP). These colors are further divided by 10, and a total of 100 color types are expressed by a hue circle, which is used as a criterion for hue determination. The hue circle is an arrangement in which the colors (1 to 100) divided into 100 colors are arranged in order in the traveling direction of the timepiece. Here, the range of each of the ten hues obtained by adding the intermediate color to the basic color is as follows.
Red (R): 1-10
Yellow-red (YR): 11-20
Yellow (Y): 21-30
Yellowish green (GY): 31-40
Green (G): 41-50
Blue-green (BG): 51-60
Blue (B): 61-70
Blue-violet (PB): 71-80
Purple (P): 81-90
Magenta (RP): 91-100
(2) Water retention: Fill the chromatographic tube with the soil to be tested, inject water so that all of the soil is submerged, let stand for 1 hour, drain water from the bottom of the chromatographic tube, and remove from the chromatographic tube for 3 minutes. The amount of water retained when the water no longer falls was measured, and converted into the amount of water retained for 100 cc of the soil to be tested as water retention. The amount of water retained is measured by filling the chromatographic tube with 140 cc of the soil to be tested, adding water from the top, measuring the weight after a predetermined time, and subtracting the weight of the soil to be tested previously measured. did.
(3) Fertilizer: Using a general-purpose extraction / filtration device “CEC-10 Ver. 2” manufactured by Fujihira Kogyo Co., Ltd., an extract of a plant growth medium using each artificial soil particle was prepared, and this was used as a cation. A sample for measuring the exchange capacity was used. And the cation exchange capacity | capacitance (meq / 100g) of each culture medium for plants was measured using the soil and crop body comprehensive analyzer "SFP-3" by Fujihira industry.

  Regardless of the types of artificial soil particles and artificial soil aggregates containing the pH indicators of Examples 1 to 22, changes in pH of the plant growth medium could be easily determined visually. In the combination of Congo Red and Neutral Red in Example 17, the red color in the neutral region (pH 5 to 7) was emphasized, and the change in the pH of the plant growth medium could be reliably determined visually. In the combination of methyl red and bromothymol blue in Examples 18-21, the yellow color in the neutral region (pH 5-7) is emphasized regardless of the shape of the artificial soil particles and the concentration of the pH indicator, and the pH of the plant growth medium is increased. The change could be reliably judged visually. In the combination of methyl red and cresol red in Example 22, the yellow color in the neutral region (pH 6 to 7) was emphasized, and the change in the pH of the plant growth medium could be reliably determined visually. Furthermore, in the combination of the several pH indicator of Examples 17-22, the change of the color of a plant growth culture medium was emphasized, and it became a thing favored also as an interior goods. In addition, about water retention and fertilizer retention, the influence by addition of a pH indicator was not recognized but the favorable value was shown.

  The artificial soil particles and plant growth medium of the present invention can be used for plant cultivation performed in a plant factory or the like, but as other uses, a soil culture medium for horticulture, a soil culture medium for greening, a molded soil medium, a soil improvement It can also be used for agents.

DESCRIPTION OF SYMBOLS 1 Filler 2 pH indicator 3 Fiber 4 Pore 5 Communication hole 10 Fiber lump (base part)
20 Coating layer 50 (50a, 50b) Artificial soil particles

Claims (6)

Artificial soil particles containing a pH indicator that changes color according to the hydrogen ion concentration,
The pH indicator includes a plurality of types of pH indicators, and each pH indicator is an artificial soil particle that is combined so as to exhibit the same hue in a region where the hydrogen ion concentration is 5 to 7.5. Said plurality of kinds of pH indication agents, combination of the Congo red and neutral red, claim is at least one selected from the combinations of the combination of methyl red and bromothymol blue, or methyl red and cresol red artificial soil particles according to 1. A base portion formed by collecting a plurality of fillers having pores so that a communication hole is formed between the fillers, and the pH indicator is carried at least in a region extending from the inside of the communication hole to the surface of the base portion. The artificial soil particle according to claim 1 or 2 . The artificial soil particle according to claim 3 , wherein ion exchange capacity is imparted to the pores. A base assembled fibers, and a coating layer covering the base, artificial soil particle according to claim 1 or 2 are allowed to support the pH indicator in at least the coating layer. The plant growth culture medium using the artificial soil particle as described in any one of Claims 1-5 .