JP6165259B2 - Artificial soil particles and artificial soil medium - Google Patents

Description

  The present invention relates to artificial soil particles and an artificial soil 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. The plant factories so far have mainly focused on hydroponic cultivation of leafy vegetables such as lettuce, but recently there is a movement to try cultivation of root vegetables that are not suitable for hydroponic cultivation in plant factories. In order to cultivate root vegetables in a plant factory using artificial soil, it is necessary to develop artificial soil particles that are excellent in basic performance as soil, high in quality, and easy to handle. Artificial soils are required to have unique functions that are difficult to realize in natural soils, such as reducing the number of watering of plants and facilitating the management of water content.

  Patent Document 1 proposes an artificial aggregate in which particles made of an inorganic material are entangled with an organic material made of organic plant fibers and the like, and solidified into particles with a binder. This artificial aggregate is intended to improve water retention by using organic plant fiber or the like as an organic material.

JP 2001-204245 A

  In the development of artificial soil, a function capable of maintaining water retention and air permeability appropriately while achieving the same plant growth ability as natural soil is required. In particular, maintaining the air permeability of artificial soil while ensuring the water that can be used by plants (easy-to-use water) is to reduce the number of watering times for plants and the optimal cultivation schedule according to the type of plant. It is necessary to realize. Here, the air permeability of the artificial soil is related to the gap formed between the artificial soil particles constituting the artificial soil, and maintaining the gap in an optimum state leads to realizing high air permeability. .

  In this regard, the artificial aggregate of Patent Document 1 is obtained by entangled an inorganic material with organic plant fibers and the like and granulated with a binder, and the organic plant fibers are present in the surface layer portion of the artificial aggregate. . Since organic plant fiber has strong hydrophilicity, water is easily adsorbed on the surface layer portion of the artificial aggregate, so that excess moisture is retained between the artificial aggregates for a long period of time. As a result, the air permeability of the artificial aggregate may be reduced.

  This invention is made | formed in view of the said problem, and it aims at providing the artificial soil particle which can maintain high air permeability, maintaining favorable water retention. Moreover, it aims at providing the artificial soil culture medium which uses the said artificial soil particle.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
A base formed by gathering fibers;
A hygroscopic porous coating layer covering the base;
It is in having.

  According to the artificial soil particle of this structure, a space | gap is formed between the fibers of a base and a water | moisture content can be hold | maintained in the said space | gap. In addition, since the base is covered with the hygroscopic porous coating layer, moisture existing outside the artificial soil particles is absorbed by the hygroscopic porous coating layer, and the external moisture environment can be adjusted. As a result, water retention and air permeability as an artificial soil culture medium that is an aggregate of artificial soil particles can be ensured, and the water environment for the cultivated plant can be maintained in a good state.

In the artificial soil particles according to the present invention,
It is preferable to have a water characteristic that the pF value reaches 1.7 within 24 hours after irrigation.

  According to the artificial soil particle of this structure, since it has the water | moisture-content characteristic that pF value reaches | attains 1.7 within 24 hours after irrigation, it is hard to accumulate excess water | moisture content outside the artificial soil particle. As a result, good air permeability as an artificial soil medium that is an aggregate of artificial soil particles can be ensured, and the water environment for the cultivated plant can be maintained in an optimal state.

In the artificial soil particles according to the present invention,
It is preferable to have a moisture characteristic where the pF value is in the range of 1.7 to 2.7 for 48 hours or more.

  According to the artificial soil particle of this structure, since it has the water | moisture content which exists in the range of 1.7-2.7 over 48 hours or more, the water | moisture content which a plant can utilize, what is called easy-effect water is used. It can be held for a long time inside the artificial soil particles. Therefore, once irrigation is performed, water can be continuously supplied from the artificial soil particles to the cultivated plant over a long period of time, and as a result, the number of times of watering the plant can be reduced.

In the artificial soil particles according to the present invention,
It is preferable that the gas phase ratio at a pF value of 1.5 is set to 30% or more.

  According to the artificial soil particles of this configuration, since the gas phase rate at a pF value of 1.5 is set to 30% or more, water retention and air permeability are balanced at a high level, and easy-to-use water is ensured optimally. can do. As a result, it is possible to reduce the number of times of watering a plant or to realize an optimal cultivation schedule according to the type of plant.

In the artificial soil particles according to the present invention,
The ratio a / b between the thickness a of the hygroscopic porous coating layer and the diameter b of the base is preferably set to 1/1000 to 1/200.

  According to the artificial soil particles of this configuration, by setting the ratio a / b between the thickness a of the hygroscopic porous coating layer and the diameter b of the base to 1/12000 to 1/200, The holding ability and the function of adjusting the external moisture environment can be balanced at a high level. As a result, good water retention and air permeability as an artificial soil medium that is an aggregate of artificial soil particles can be ensured, and the water environment can be maintained in an optimum state for the cultivated plants.

In the artificial soil particles according to the present invention,
The thickness a of the hygroscopic porous coating layer is preferably 5 to 10 μm.

  According to the artificial soil particle of this configuration, by setting the thickness a of the hygroscopic porous coating layer to 5 to 10 μm, excess moisture existing outside the artificial soil particle is quickly absorbed by the hygroscopic porous coating layer. Therefore, the external moisture environment can be easily adjusted. Therefore, it is possible to prevent water from accumulating outside the artificial soil particles, and to ensure good air permeability as an artificial soil medium that is an aggregate of artificial soil particles.

In the artificial soil particles according to the present invention,
The diameter b of the base is preferably 2 to 6 mm.

  According to the artificial soil particles of this configuration, by setting the base diameter b to 2 to 6 mm, it is possible to configure artificial soil particularly suitable for cultivation of root vegetables while sufficiently securing the capacity of the base.

In the artificial soil particles according to the present invention,
The hygroscopic porous coating layer is made of diatomaceous earth, perlite, vermiculite, zeolite, bentonite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, kanemite, nontronite, soconite, talc, mica (mica), Iraite, It is preferable to include at least one porous material selected from the group consisting of macatite and kenyaite.

  According to the artificial soil particle of this configuration, the hygroscopic porous coating layer contains the porous material having the hygroscopic property described above, so that moisture existing outside the artificial soil particle is transferred to the hygroscopic porous coating layer. It is reliably absorbed and the external moisture environment can be easily adjusted. Therefore, it is possible to prevent moisture from accumulating outside the artificial soil particles, and to ensure good air permeability as an artificial soil medium that is an aggregate of artificial soil particles.

The characteristic configuration of the artificial soil culture 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 artificial soil medium of this configuration, since the artificial soil particles of the present invention are used, moisture can be retained inside the artificial soil particles, and the moisture environment outside the artificial soil particles can be optimized. Can be adjusted to the condition. Therefore, good water retention and air permeability can be ensured, and the moisture environment for the cultivated plant can be maintained in a good state. Such an artificial soil medium can be suitably used in a plant factory or the like.

FIG. 1 is an explanatory view schematically showing artificial soil particles according to the present invention. FIG. 2 is an explanatory view schematically showing a state in which a plant is planted in an artificial soil medium using artificial soil particles according to the present invention. FIG. 3 is a graph showing the change over time of the pressure head of the artificial soil medium. FIG. 4 is a graph showing the relationship between the water retention time and the gas phase rate in the pF value range of 1.7 to 2.7 of the artificial soil medium.

  Hereinafter, the embodiment regarding the artificial soil particle which concerns on this invention, and the artificial soil culture medium using the said artificial soil particle is described based on FIGS. 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 schematically showing artificial soil particles 50 according to the present invention. The artificial soil particle 50 includes a base 10 formed by collecting the fibers 1 and a hygroscopic porous coating layer 2 that covers the base 10. As shown in FIG. 1, the base 10 is granulated in a state where the fibers 1 are gathered in a complicated manner, and is formed in a granular shape. The hygroscopic porous coating layer 2 contains a hygroscopic porous material. For example, the porous material is mixed with a resin material to form a paste, and the outer surface portion of the base 10 is coated with the porous material-containing paste. By doing so, the hygroscopic porous coating layer 2 is formed. In the present embodiment, the artificial soil particles 50 are configured in a three-dimensional shape close to a spherical shape as shown in FIG. 1. For example, the artificial soil particles 50 have a flat rugby ball shape, a confetti shape with protrusions, a polyhedral shape, a certain amount or more. It is also possible to configure a plate having a thickness, an indefinite shape, or the like.

  The form of the fiber 1 used for forming the base 10 is a long fiber or a short fiber. Short fibers also include powdered fibers having a very short fiber length. By granulating long fibers or short fibers, the base 10 in which the fibers 1 are assembled is formed. When granulating, it is also possible to use a binder such as resin or glue as necessary. A gap 3 is formed between the aggregated fibers 1 inside the base 10. The base 10 can retain moisture in the gap 3. Therefore, the state of the void 3 (for example, the size, number, shape, etc. of the void 3) relates to the amount of water that can be retained by the artificial soil particles 50, so-called water retention. The state of the void 3 can be adjusted by changing the amount (density) of the fiber 1 used when granulating the base 10, the type, thickness, length, and the like of the fiber 1. The size of the fiber 1 is preferably 5 to 100 μm in thickness and preferably 0.3 to 10 mm in length. Moreover, it is also possible to use the short fiber cut | disconnected previously as the fiber 1, and the length of a short fiber is preferable about 0.2-0.5 mm in this case.

  The artificial soil particles 50 preferably use hydrophilic fibers as the fibers 1 so that the base 10 can retain moisture. Thereby, the water retention of the artificial soil particle 50 can be improved. As the type of the fiber 1, natural fiber or synthetic fiber is appropriately selected. Preferable hydrophilic fibers include, for example, cotton, wool, rayon, cellulose and the like for natural fibers, and vinylon, urethane, nylon, acetate and the like for synthetic fibers. Of these fibers, cotton, cellulose, and vinylon are more preferable. As the fiber 1, it is possible to use a mixture of natural fiber and synthetic fiber.

  Since the porous substance contained in the hygroscopic porous coating layer 2 has high hygroscopicity, the hygroscopic porous coating layer 2 is in a state where the surface is wet with water even when moisture is absorbed (moist state). It has the characteristic that it is difficult to become. Therefore, the artificial soil particles 50 adjust the water environment by absorbing the moisture present outside even in an environment where a large amount of moisture exists outside, and the surface of the artificial soil particles 50 Can be maintained in a state not wet with water (non-sticky state). Thereby, it becomes difficult for water to accumulate between the artificial soil particles 50, and the air permeability as the artificial soil medium can be ensured. As a result, plant root rot and the like due to a decrease in drainage of the medium can be prevented.

  Moreover, the intensity | strength and durability of the artificial soil particle 50 improve by coat | covering the base 10 with the hygroscopic porous coating layer 2. FIG. Therefore, the artificial soil particles 50 can have water retention, hygroscopicity, air permeability, strength, and durability characteristics in parallel. In addition, the hygroscopic porous coating layer 2 is in a state in which the hygroscopic porous coating layer 2 is fitted slightly inward from the outer surface portion of the base portion 10 so as to reinforce the entangled portions of the fibers 1 constituting the base portion 10 (portions where the fibers 1 contact each other) It may be formed. Thereby, the intensity | strength and durability of the artificial soil particle 50 can further be improved.

  As the porous material used for the hygroscopic porous coating layer 2, diatomaceous earth, perlite, vermiculite, zeolite, bentonite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, kanemite, nontronite, soconite, talc, Porous substances such as mica (mica), Iraite, macatite, and Kenyaite can be mentioned, and diatomaceous earth is preferable. In addition, the above-mentioned porous materials can be used in a state where two or more kinds are mixed.

  As the resin material used for coating the outer surface portion of the base portion 10 with the porous substance, a resin material that is insoluble in water and hardly oxidized is preferable. 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. Instead of resin materials, use polymer gelling agents such as polyethylene glycol and acrylamide, natural polysaccharide gelling agents such as alginate and carrageenan, rubber coating agents such as natural rubber and silicone rubber, etc. Is also possible.

  The artificial soil particles 50 hold water in the gaps 3 between the fibers 1 of the base 10 and adjust the external moisture environment by the hygroscopic porous coating layer 2. Therefore, in order to maintain the balance between the water retention of the artificial soil particles 50 and the external moisture environment, the thickness a of the hygroscopic porous coating layer 2 and the diameter b of the base 10 of the artificial soil particles 50 are appropriately sized. Must be set to In the present embodiment, the thickness a of the hygroscopic porous coating layer 2 is set to 5 to 10 μm, preferably 5 to 7 μm. If the thickness a of the hygroscopic porous coating layer 2 is set to be smaller than 5 μm, water existing outside the artificial soil particles cannot be sufficiently absorbed, and it may be difficult to adjust the external moisture environment. is there. Moreover, since the hygroscopic porous coating layer 2 provides the artificial soil particles 50 with a certain rigidity, if the thickness a is set to be smaller than 5 μm, sufficient strength and durability of the artificial soil particles 50 cannot be obtained. There is also a fear. On the other hand, if it is set to be larger than 10 μm, the water permeability between the inside and the outside of the base 10 is deteriorated, it becomes difficult to retain water in the base 10, and the water retention of the artificial soil particles 50 may be lowered. Further, when the thickness a of the hygroscopic porous coating layer 2 is increased, the absorbed water may remain in the hygroscopic porous coating layer 2 and may not reach the base 10. The diameter b of the base 10 is set to 2 to 6 mm, preferably 2 to 4 mm. If the diameter b of the base 10 is smaller than 2 mm, it becomes difficult to store sufficient moisture in the base 10, and the water retention of the artificial soil particles 50 may be reduced. On the other hand, if the diameter b of the base 10 is larger than 6 mm, the gap between the artificial soil particles becomes too large, the drainage property as the artificial soil medium becomes excessive, the plant becomes difficult to absorb sufficient moisture, and may die. There is. Further, in the relationship between the thickness a of the hygroscopic porous coating layer 2 and the diameter b of the base portion 10, it is also important to set the ratio a / b within an appropriate range. In this embodiment, the ratio a / b b is set to 1/1200 to 1/200, preferably 1/12000 to 1/300. If the ratio a / b is set to be smaller than 1/1200, the thickness of the hygroscopic porous coating layer 2 becomes too thin with respect to the base 10, and the water existing outside cannot be sufficiently absorbed, and the external moisture It may be difficult to adjust the environment. On the other hand, if the ratio a / b is set larger than 1/200, the base 10 becomes relatively small with respect to the hygroscopic porous coating layer 2, and the artificial soil particles 50 may not be able to hold water sufficiently. There is.

  In designing the artificial soil particles 50, for example, a water retention material can be introduced into the base 10 in order to further increase the water retention of the base 10. In this case, the artificial soil particles 50 can be provided with water retention by the water retention material in addition to the water retention by the gaps 3 between the fibers 1 that the base 10 originally has. As a method for introducing the water retention material into the base portion 10, for example, the water retention material is added when the base portion 10 is formed by granulating the fibers 1. The water retention material introduced into the base 10 is preferably exposed in the gap 3 of the base 10. In this case, since the water retention material present in the void 3 directly absorbs moisture and the water retention capacity of the artificial soil particles 50 is greatly improved, for example, it is suitably used as a soil improvement material added to a dry environment such as a desert. can do.

  As the water retention material introduced into the base portion 10, a polymer water retention material having water absorption is preferably used. For example, polyacrylate polymer, polysulfonate polymer, polyacrylamide polymer, polyvinyl alcohol polymer, polyalkylene oxide polymer and other synthetic polymer water retention materials, polyaspartate polymer, polyglutamate Natural polymer water-retaining materials such as polymer, polyalginate polymer, cellulose polymer and starch. These water retaining materials can be used in combination of two or more. Moreover, it is also possible to use porous materials, such as ceramics, as a water retention material.

By the way, since natural soil has the property of taking in cations, it has the ability to retain K ⁺ , Ca ²⁺ , Mg ²⁺ , and ammonia nitrogen (NH ₄ ⁺ ), that is, fertilizer. Plants cannot effectively use ammonia nitrogen as a nitrogen source, but because nitrifying bacteria are resident in natural soil, these nitrifying bacteria convert ammonia nitrogen to nitrate nitrogen necessary for plants, Supplying to plants. Therefore, in the case of using artificial soil instead of natural soil in a plant factory or the like, it is necessary to provide the artificial soil particles 50 with ion exchange capacity and to provide fertilizer.

Here, since the nutrients necessary for the plant are nitrate nitrogen (NO ₃ ⁻ ), K ⁺ , Ca ²⁺ , and Mg ²⁺ , the artificial soil particles 50 have both ions in order to retain these nutrients. It must have adsorption capacity. Therefore, when forming the artificial soil particles 50, a cation exchange filler and an anion exchange filler are added, and nitrate nitrogen (NO ₃ ⁻ ), K ⁺ , Ca ²⁺ , Mg ²⁺ contained in moisture taken from the outside is added. It is made possible to adsorb the ions including Incidentally, NO ₃ ^- is a pollutant of rivers and groundwater and an artificial soil particles 50 are added anion-exchange filler, even gave many nutrients nitrate nitrogen, NO ₃ ^- artificial soil particles 50 Since it can be held inside, the outflow to the water environment is suppressed.

  In order to impart ion exchange capacity to the artificial soil particles 50, it is preferable to add a cation exchange filler and an anion exchange filler to at least one of the base 10 and the hygroscopic porous coating layer 2. When the ion exchange capacity is imparted to the base 10, the fiber 1 may be granulated by mixing the cation exchange filler and the anion exchange filler when the fiber 1 is granulated. In the case of imparting performance, a cation exchange filler and an anion exchange filler may be mixed with the above-described porous substance-containing paste and coded on the outer surface of the base 10. Further, a cation exchange filler and an anion exchange filler may be added to the base 10 and the hygroscopic porous coating layer 2 respectively, and the cation exchange filler and the anion exchange filler are separately added to the base 10 and the hygroscopic porous. It may be added to the coating layer 2. In addition, when the porous substance used for the formation of the hygroscopic porous coating layer 2 already has an ion exchange capacity and has a sufficient fertilizer, it is necessary to add a new filler having an ion exchange capacity. It may not be added to the hygroscopic porous coating layer 2.

  Examples of the cation exchange filler include cation exchange minerals such as smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, zeolite, humus, and cation exchange resins. . 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 fillers are anion exchange minerals such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, natural layered double hydroxide, synthetic hydrotalcite having double hydroxide as the main skeleton. And hydrotalcite-like substances, clay minerals such as allophane, imogolite and kaolin, and anion exchange resins. 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.

<Method for producing artificial soil particles>
The manufacturing method of the artificial soil particle 50 of this invention is demonstrated. First, the base 10 serving as the base of the artificial soil particles 50 is formed. For example, the fibers 1 such as cotton, cellulose fiber, or vinylon are aligned with a carding device or the like and cut to a length of about 3 to 10 mm. When the cut fiber 1 is granulated by a method such as rolling granulation, fluidized bed granulation, stirring granulation, compression granulation, extrusion granulation, the base 10 is obtained. The base 10 can be efficiently formed by mixing a binder such as resin or glue into the fiber 1 during granulation.

  As the binder, an organic binder or an inorganic binder can be used. Organic binders include, for example, synthetic resin binders such as polyolefin binders, polyvinyl alcohol binders, polyurethane binders, polyvinyl acetate binders, polysaccharides such as starch, carrageenan, xanthan gum, gellan gum, alginic acid, and animal properties such as glue. Examples include natural product-based binders such as proteins. 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. If fibers 1 that are easily entangled (for example, bent fibers) are used, the fibers 1 are easily entangled with each other simply by granulation. In this case, the base 10 is formed without using a binder. Is possible.

  Next, the granulated base 10 is transferred to a container, and about half of the volume (occupied volume) of the base 10 is added to immerse the water in the gap 3 of the base 10. Further, a paste in which a predetermined amount of diatomaceous earth as a hygroscopic porous material is added to a polyethylene emulsion having a volume of 1/3 to 1/2 of the volume of the base 10 is added to the base 10 soaked with water. The polyethylene emulsion may be mixed with additives such as pigments, fragrances, bactericides, antibacterial agents, deodorants, and insecticides. Then, the paste is impregnated from the outer surface of the base 10 while rolling so that the paste uniformly adheres to the outer surface of the base 10. At this time, the water stays in the center of the base 10, so that the paste stays near the outer surface of the base 10. Thereafter, the base 10 coated with the paste is dried in an oven at 60 to 80 ° C., and then the polyethylene contained in the paste is melted at 100 ° C., and the polyethylene is fused to the fibers 1 near the outer surface of the base 10. The hygroscopic porous coating layer 2 is formed. Thereby, the artificial soil particle 50 by which the outer surface part of the base 10 was coat | covered with the hygroscopic porous coating layer 2 containing diatomaceous earth is completed. In the hygroscopic porous coating layer 2, when the polyethylene melts, the solvent contained in the polyethylene emulsion evaporates, and the evaporation trace of the solvent has a porous structure. The porous structure communicates the inside and the outside of the base 10 and maintains the air permeability and water permeability of the base 10. The obtained artificial soil particles 50 are dried and classified as necessary, and the particle size is adjusted.

  When granulating the base 10, when using short fibers as the fibers 1, a polyethylene emulsion containing diatomaceous earth is added little by little while stirring the short fibers with a stirring and mixing granulator. As a result, the short fibers forming the base 10 are partially fixed, and the strong base 10 can be formed. It is also possible to add water to the short fibers and granulate them first, and then add a polyethylene emulsion containing diatomaceous earth to finish the base 10.

<Artificial soil medium using artificial soil particles>
FIG. 2 is an explanatory view schematically showing a state in which the plant 30 is planted in the artificial soil culture medium 100 using the artificial soil particles 50 according to the present invention. As shown in FIG. 2, in the artificial soil medium 100, a certain gap 31 is formed between the artificial soil particles 50. Since this gap 31 allows air and water to pass through, excess moisture can be discharged while holding moisture necessary for plants in the gap 31. Since the artificial soil particle 50 of the present invention has the hygroscopic porous coating layer 2, the moisture environment of the gap 31 can be adjusted appropriately. When the artificial soil medium 100 is in a wet state, the hygroscopic porous coating layer 2 of the artificial soil particles 50 absorbs excess moisture from the gaps 31, and ensures the air permeability of the artificial soil medium 100 quickly. The root rot of the plant 30 can be prevented. When the artificial soil culture medium 100 is in a dry state, the artificial soil particles 50 release the water retained in the base 10 from the hygroscopic porous coating layer 2 to the gap 31 and supply it to the plant 30. As described above, the artificial soil culture medium 100 can appropriately adjust the moisture environment of the gap 31 between the artificial soil particles 50 by the hygroscopic porous coating layer 2 of the artificial soil particles 50. As a result, the artificial soil Excellent water retention and air permeability of the culture medium 100 is realized.

  By the way, the force with which the soil retains moisture is expressed as a pF value. The pF value is a common logarithm of the soil water suction pressure (pressure head) expressed in terms of the height of the water column, and is an index representing the degree to which the moisture in the soil is attracted by the capillary force of the soil. is there. For example, when the pF value is 2.0, it corresponds to a pressure of 100 cm of water column. The pF value also represents the strength of soil and moisture adsorption. If the soil and moisture adsorption force is weak, the pF value becomes low, and the plant roots easily absorb moisture. On the other hand, if the adsorption power of soil and moisture is strong, the pF value becomes high, and a large force is required for the roots of plants to absorb moisture. When there is no air in the gaps in the soil, the state when all is filled with water has a pF value of 0, and the state where only water combined with the soil is present in the heat-dried soil at 100 ° C. The value is 7. The water in the soil that the plant can absorb from the roots is the water from the water remaining in the soil (pF1.7), usually 24 hours after rainfall or irrigation, to the initial wilting point (pF3.8) where the plant begins to wither. It is. The range of the pF value of water capable of cultivating plants, so-called easy-to-use water, is 1.7 to 2.7 (pressure head: 50 to 500 cm). If the state where the moisture content is less than 1.7 (pressure head: 50 cm) continues, it becomes difficult to absorb oxygen from the roots of the plant, and root rot may occur. On the other hand, when there is only water whose pF value exceeds 2.7 (pressure head: 500 cm), the plant becomes difficult to absorb sufficient water, and the plant may die. The pF value can be measured using a pF meter (tensiometer).

  Generally, in order for plants to grow using moisture in the soil, after irrigation, moisture with a pF value of less than 1.7 is drained within 24 hours, and moisture with a pF value in the range of 1.7 to 2.7 is obtained. For 48 hours or more. That is, if the pF value in the above range can be maintained for a predetermined time or more, the plant growth does not decrease even if the frequency of irrigation is reduced, and the opportunity for maintenance such as irrigation can be reduced. As described above, the artificial soil particle 50 of the present invention includes the hygroscopic porous coating layer 2 that adjusts the external moisture environment. The porous porous coating layer 2 can absorb moisture present in the gaps 31, and can quickly increase the pF value of the artificial soil culture medium 100 to 1.7 or more. In constructing the artificial soil medium 100 using the artificial soil particles 50, the time for the pF value of the artificial soil medium 100 to reach 1.7 after irrigation is within 24 hours, preferably within 10 hours. To be prepared. Since the artificial soil particles 50 can hold water in the base 10, the artificial soil medium 100 can hold easy-to-use water for a long time. The artificial soil culture medium 100 is prepared so that the time which can hold | maintain the water of the range of pF1.7-2.7 is 48 hours or more, Preferably it is 70 hours or more. The artificial soil culture medium 100 prepared in this way can be quickly adjusted to an optimal moisture environment for the plant 30 and can retain moisture in the range of pF value 1.7 to 2.7 for a long time, so that irrigation, etc. Maintenance opportunities can be reduced.

  Moreover, in order for plants to grow, it is necessary to appropriately adjust the gas phase rate of the soil and ensure the air permeability of the soil. For example, if the moisture content is high when the pF value is low, plant damage is likely to occur. Therefore, even when the pF value is low, it is necessary to maintain the air permeability of the soil above a certain level. An index indicating the air permeability of the soil when the pF value is low is represented by a gas phase rate at a pF value of 1.5. The vapor phase rate of the soil at a pF value of 1.5 is the vapor phase rate of the soil (state where drainage due to gravity is not completely completed) after about 20 to 50 hours of rainfall per day. is there. In order to sufficiently grow plants planted in soil, it is necessary to set the gas phase rate at a pF value of 1.5 to 30% or more. In the artificial soil culture medium 100 of the present invention, the gas phase rate at a pF value of 1.5 is adjusted to 30 to 80%, preferably 40 to 70%. For this reason, the artificial soil culture medium 100 is balanced in a dimension with high water retention (especially easy water retention) and air permeability, and can realize high added value artificial soil having a unique function not found in natural soil. It will be a thing. That is, since water (easily effective water) that can be used by the plant can be optimally secured, it is possible to reduce the number of times of watering the plant or to realize an optimal cultivation schedule according to the type of plant.

  Next, the Example regarding the artificial soil culture medium using the artificial soil particle of this invention is described. In the examples, the pressure head of the artificial soil particles, the water retention time in the range of 1.7 to 2.7, and the gas phase rate are measured, the change of the pressure head due to the difference of the artificial soil particles, and the pF value. The relationship between the retention time of water in the range of 1.7 to 2.7 and the gas phase rate was evaluated.

[Production of artificial soil particles]
Prior to evaluation, a method for producing artificial soil particles used in the examples will be described. A polyethylene emulsion (Separjon (registered trademark) G315) with an apparent volume of 1000 cc vinylon short fibers (length: 0.5 mm, manufactured by Kuraray Co., Ltd.) stirred and rolled with a stirring and mixing granulator (manufactured by G-Labo Co., Ltd.) , Manufactured by Sumitomo Seika Co., Ltd., concentration of about 40% by weight) was added and granulated to form a particulate base part impregnated with a polyethylene emulsion. Next, the same polyethylene emulsion, which is 2% of the base volume, and diatomaceous earth, which is 26% of the base volume, are mixed to form a paste, and the paste is added to the base and impregnated while rolling so that the paste adheres uniformly. I let you. After the base part impregnated with the paste is dried at 60 ° C. using an oven, the polyethylene in the emulsion is melted and fused to the fiber at 100 ° C., thereby fixing the vinylon short fibers forming the base part, The artificial soil particles whose base was covered with a hygroscopic porous coating layer containing diatomaceous earth were obtained. Artificial soil particles were sieved and adjusted so that the particle size was in the range of 2.0 to 5.6 mm. In addition, the artificial soil particle of Comparative Examples 1-3 did not coat | cover the particulate base part with a hygroscopic porous coating layer, and was used as artificial soil particle as it was. The artificial soil particle of Comparative Example 4 is not a structure in which the particulate base is covered with a hygroscopic porous coating layer, but is a granulated solidified porous material with a resin binder. In Comparative Example 5, a commercially available natural culture soil is used as it is.

[Evaluation of temporal change of pressure head due to difference in artificial soil particles]
The artificial soil culture media of Examples 1 and 2 and the artificial soil culture media of Comparative Examples 1 to 4 were prepared as follows. In Comparative Example 5, general culture soil was used.
(1) Example 1: Artificial soil particles were prepared to a particle size of 2 to 4 mm using a 2 mm over and 4 mm under sieve and used as an artificial soil medium.
(2) Example 2: Artificial soil particles were prepared to a particle size of 4 to 5.6 mm using a sieve of 4 mm over and 5.6 mm under, and used as an artificial soil medium.
(3) Comparative Example 1: Artificial soil particles were prepared to a particle size of 2 to 4 mm using a 2 mm over and 4 mm under sieve and used as an artificial soil medium.
(4) Comparative Example 2: Artificial soil particles were prepared to a particle size of 4 to 5.6 mm using a sieve of 4 mm over and 5.6 mm under and used as an artificial soil medium.
(5) Comparative Example 3: Used as an artificial soil medium without classification with a sieve.
(6) Comparative Example 4: Diatomaceous earth was used as the porous material, and polyethylene emulsion was used as the binder. 100 parts by weight of diatomaceous earth (Radiolite (registered trademark) F, manufactured by Showa Chemical Industry Co., Ltd.) and 5 parts by weight of a polyethylene emulsion "Sepoljon (registered trademark) G" manufactured by Sumitomo Seika Co., Ltd. are mixed with stirring. The granulated material was sieved and classified to prepare artificial soil particles of 2 mm over and 4 mm under, and used as an artificial soil medium.
(7) Comparative Example 5: Commercially available natural culture soil (manufactured by Takasawa Farm) was used.

<Test content>
Pressure head: The pressure head value with time change of each sample was measured with a tensiometer.

<Test results>
FIG. 3 is a graph showing the change over time of the pressure head of the artificial soil medium. In this graph, a pressure head of 50 cm corresponds to a pF value of 1.7, and a pressure head of 500 cm corresponds to a pF value of 2.7. As shown in FIG. 3, the artificial soil culture media of Examples 1 and 2 had substantially the same ability to retain ready-to-use water as compared to the artificial soil culture media of Comparative Examples 1 to 3 that were not coated with diatomaceous earth. However, the time to reach a pF value of 1.7 was 70 hours for the artificial soil culture media of Comparative Examples 1 to 3, whereas Examples 1 and 2 reached within 20 hours. It was confirmed that the artificial soil medium of Example 2 was excellent in air permeability. Moreover, about the time to hold | maintain the water (easily effective water) of the range of pF value 1.7-2.7, the artificial soil culture medium of Example 1 is 80 hours or more, and the artificial soil culture medium of Example 2 is 55 hours or more. In contrast, the artificial soil medium of Comparative Example 4 was 35 hours, and the natural cultured soil of Comparative Example 5 was 50 hours. The artificial soil medium of Examples 1 and 2 was confirmed to be able to retain water over a longer period than the artificial soil medium of Comparative Example 4, and further from Comparative Example 5 using natural cultured soil having excellent water retention. The result was also good. Thus, since the artificial soil particles of the present invention adjust the external moisture environment with diatomaceous earth, it was shown that easy-to-use water can be maintained for a long time while maintaining a certain level of air permeability.

[Evaluation of retention time and gas phase ratio of water in the range of pF value 1.7 to 2.7]
The same artificial soil particles as those described in “Evaluation of temporal change of pressure head due to difference in artificial soil particles” were used.

<Test content>
(1) pF value: The pF value of each sample was measured with a tensiometer, and the time for changing from a pF value of 1.7 to a pF value of 2.7 was measured.
(2) Gas phase rate at a pF value of 1.5: The weight of the sample was allowed to flow down, and after confirming that the pF value of the sample showed 1.5 by a pF meter (tensiometer), the shape of the sample was as much as possible While maintaining, it collected in the cylinder for 100 mL samples, and set it as the digital real volume measuring apparatus "DIK-1150" made by Dairika Kogyo Co., Ltd., and the value measured was made into the gas phase rate in pF value 1.5.

<Test results>
FIG. 4 is a graph showing the relationship between the water retention time and the gas phase rate in the pF value range of 1.7 to 2.7 of the artificial soil medium. Compared with the artificial soil culture medium of Comparative Examples 1-4 and the natural culture soil of Comparative Example 5, the artificial soil culture medium of Example 1 was excellent in the ability to hold easy water and air permeability. Regarding the artificial soil medium of Example 2, compared with the artificial soil medium of Comparative Examples 1 to 3 and the natural cultured soil of Comparative Example 5, the retention capacity of easy-to-use water was substantially the same, but the pF value was 1. The gas phase rate at 5 was 50% or more, indicating a high value. Moreover, compared with the artificial soil culture medium of the comparative example 4, the retention ability and air permeability of easy-effect water were excellent. Thus, since the artificial soil particles of the present invention adjust the external moisture environment with diatomaceous earth, it was shown that the artificial soil particles have a high gas phase rate of 50% or more while maintaining water retention above a certain level. .

  The artificial soil particles according to the present invention and the artificial soil medium using the artificial soil particles can be used in agriculture and horticulture in home gardens, plant factories, indoor greening, and the like.

DESCRIPTION OF SYMBOLS 1 Fiber 2 Hygroscopic porous coating layer 10 Base 50 Artificial soil particle 100 Artificial soil culture medium

Claims (9)

A base formed by gathering fibers;
A hygroscopic porous coating layer covering the base;
Artificial soil particles with.   The artificial soil particle according to claim 1, having a water characteristic that a pF value reaches 1.7 within 24 hours after irrigation.   The artificial soil particle according to claim 1 or 2, wherein the artificial soil particle has a water characteristic having a pF value in a range of 1.7 to 2.7 for 48 hours or more.   The artificial soil particle according to any one of claims 1 to 3, wherein a gas phase ratio at a pF value of 1.5 is set to 30% or more.   The ratio a / b between the thickness a of the hygroscopic porous coating layer and the diameter b of the base is set to 1/1200 to 1/200, and the artificial according to any one of claims 1 to 4. Soil particles.   The artificial soil particle according to claim 5, wherein a thickness a of the hygroscopic porous coating layer is 5 to 10 μm.   The artificial soil particle according to claim 5 or 6, wherein the diameter b of the base is 2 to 6 mm.   The hygroscopic porous coating layer is made of diatomaceous earth, perlite, vermiculite, zeolite, bentonite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, kanemite, nontronite, soconite, talc, mica (mica), Iraite, The artificial soil particle according to any one of claims 1 to 7, comprising at least one porous material selected from the group consisting of macatite and kenyaite.   The artificial soil culture medium using the artificial soil particle as described in any one of Claims 1-8.

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