Cultivation soil and method for growing plants using same

Abstract

This cultivation soil contains soil and silica particles. The cultivation soil has an upper layer part and a lower layer part. The concentration of silica particles in the upper layer part is different from the concentration of silica particles in the lower layer part.

Description

Culture soil and method for growing plants using the same

[0001] The present disclosure relates to a culture soil and a method for growing plants using the same.

[0002] Patent Document 1 discloses a soil improvement material for planting containing soil generated from water purification. According to Patent Document 1, the planting soil containing the soil improvement material for planting described therein has excellent fertilizer and water retention properties, which allows the roots of planted plants to grow deep underground.

[0003] Patent Document 2 discloses a composition containing plant growth-promoting rhizobacteria and chitin. According to Patent Document 2, the composition can promote plant growth and disease resistance. In Patent Document 2, for example, tomatoes are grown in a flowerpot medium to which the composition has been added, and the growth-promoting effect on seedling growth is evaluated.

[0004] Japanese Patent Application Laid-Open No. 2020-122142 Special Publication No. 2003-529539

[0005] The planting soil described in Patent Document 1 is suitable for growing plants, and can be used particularly preferably for growing lawns. However, as lawn growth becomes more vigorous, the lawn tends to grow leggy, which may require more frequent maintenance such as mowing and aeration (root cutting).

[0006] The use of the composition described in Patent Document 2 can promote the growth of, for example, tomato seedlings. However, when tomatoes are grown in small seedling containers, they may produce fruit before being transplanted to a larger planter or field. Furthermore, the plants are unable to establish roots sufficiently in the seedling containers, which tends to prevent nutrients, oxygen, moisture, and the like from reaching the plants, resulting in a change in taste.

[0007] An object of the present disclosure is to provide a culture soil capable of controlling plant growth and a method for growing plants using the same.

[0008] One embodiment of the present disclosure is a culture medium comprising soil and silica particles, the culture medium having an upper layer and a lower layer, and the concentration of the silica particles in the upper layer being different from the concentration of the silica particles in the lower layer.

[0009] Another embodiment of the present disclosure is a method for growing plants using culture soil, the culture soil including soil and silica particles, the culture soil having an upper layer and a lower layer, the concentration of the silica particles in the upper layer being different from the concentration of the silica particles in the lower layer, and the method including the step of planting the plant in the upper layer.

[0010] Yet another embodiment of the present disclosure is a method for growing plants, comprising: growing the plants in a culture medium containing a mixture of soil and silica particles; and transplanting the seedlings obtained in the growing step into soil.

[0011] Yet another embodiment of the present disclosure is a method for growing plants, comprising: raising the plants in soil; and transplanting the seedlings obtained in the raising step into a culture medium containing a mixture of soil and silica particles.

[0012] According to the present disclosure, it is possible to provide a culture soil capable of controlling plant growth and a method for growing plants using the same.

[0013] FIG. 1 is a schematic cross-sectional view of a culture soil according to an embodiment. FIG. 2 is an explanatory diagram illustrating a plant growth method according to an embodiment. FIG. 3 is an explanatory diagram illustrating an example of a method for producing silica particles A. FIG. 4 is a scanning electron microscope image of silica particles A. FIG. 5 is a scanning electron microscope image of silica particles A. FIG. 6 is an explanatory diagram illustrating an example. FIG. 7 is an explanatory diagram illustrating an example. FIG. 8 is a diagram illustrating experimental results. FIG. 9 is a diagram illustrating experimental results. FIG. 10 is a diagram illustrating experimental results. FIG. 11 is an explanatory diagram illustrating an example. FIG. 12 is an explanatory diagram illustrating an example. FIG. 13 is a diagram illustrating experimental results. FIG. 14 is a diagram illustrating experimental results. FIG. 15 is a diagram illustrating experimental results.

[0014] Fig. 1 is a schematic cross-sectional view of a culture medium 10 according to an embodiment. The culture medium 10 includes soil and silica particles. In this specification, silica particles are aggregates of a plurality of silica particles. The culture medium 10 has an upper layer 11 and a lower layer 12. The concentration of silica particles in the upper layer 11 is different from the concentration of silica particles in the lower layer 12. In other words, the culture medium 10 is composed of two layers with different concentrations of silica particles.

[0015] As shown in FIG. 1 , the method for growing plants using culture soil according to the embodiment includes a step of planting plants in an upper layer 11 of culture soil 10 .

[0016] Fig. 2 is an explanatory diagram illustrating a method for growing plants according to another embodiment, in which the left side of Fig. 2 shows a process for raising plants in a seedling raising container, the center of Fig. 2 shows a process for transplanting the seedlings obtained in the seedling raising process, and the right side of Fig. 2 shows further growth of the transplanted seedlings.

[0017] <First embodiment> Hereinafter, a first embodiment of the culture soil and the method for growing plants using the same will be described.

[0018] [Cultivation soil] In the culture soil 10 according to the first embodiment (hereinafter also referred to as the first culture soil), the concentration of silica particles in the upper layer 11 is higher than that in the lower layer 12. As will be described later, silica particles can promote plant growth. Therefore, in the upper layer 11, where the concentration of silica particles is high, a higher growth-promoting effect is obtained. On the other hand, in the lower layer 12, where the concentration of silica particles is low, the growth-promoting effect is suppressed compared to the upper layer 11. This makes it possible to control, for example, the amount and growth rate of plants.

[0019] The type of soil constituting the first culture medium is not particularly limited as long as it is suitable for plant growth. The soil constituting the upper layer 11 and the soil constituting the lower layer 12 may be the same soil or different soils.

[0020] The concentration of silica particles in the first culture soil can be expressed, for example, by the amount of silica particles per 100g of culture soil.In this specification, the amount of silica particles in culture soil can be calculated by the measurement method described below.It should be noted that "the amount of silica particles in culture soil" refers to the content of solid silica particles present in culture soil.In other words, "the amount of silica particles in culture soil" refers to the amount of insoluble silica particles excluding the water-soluble components dissolved in culture soil.

[0021] The concentration of silica particles in the upper layer 11 can be expressed as the amount of silica particles per 100 g of the culture medium constituting the upper layer 11. The concentration of silica particles in the upper layer 11 in the first culture medium may be, for example, 20 mg / 100 g or more, preferably 50 mg / 100 g or more, more preferably 70 mg / 100 g or more, and even more preferably 100 mg / 100 g or more. The concentration of silica particles in the upper layer 11 in the first culture medium may be, for example, less than 100 g / 100 g.

[0022] The concentration of silica particles in the lower layer 12 can be expressed as the amount of silica particles per 100 g of culture soil constituting the lower layer 12. The concentration of silica particles in the lower layer 12 in the first culture soil may be, for example, 10 mg / 100 g or less, preferably 5 mg / 100 g or less, more preferably 3 mg / 100 g or less, even more preferably 1 mg / 100 g or less, or may be 0 mg / 100 g.

[0023] By setting the silica particle concentration in the upper layer 11 and the silica particle concentration in the lower layer 12 within the above ranges, plant growth can be more promoted in the upper layer 11 and more suppressed in the lower layer 12, making it possible to control the amount and growth rate of plants.

[0024] The first culture medium can be produced, for example, by preparing two types of culture medium with different concentrations of silica particles and layering the culture medium with a higher concentration of silica particles on top of the culture medium with a lower concentration of silica particles.

[0025] The silica particles constituting the first culture soil are an aggregate of a plurality of silica particles. ２The silica particles may be substantially spherical particles. ２ The particles are SiO ２ In this specification, the term "major component" refers to the component with the largest content in terms of mass among the constituent components, and may be, for example, 90 mass % or more, 95 mass % or more, or 99 mass % or more based on the total mass of all the constituent components. ２ The content of is measured by X-ray fluorescence analysis. In this specification, the remaining constituent components other than the main component are also referred to as minor components.

[0026] Silica particles are composed of carbon (C), diphosphorus pentoxide (P ２ O ５ ), sulfur trioxide (SO ３ ), chlorine (Cl), sodium (Na) and nitrogen (N) may further contain one or more elements or compounds selected from these as sub-components. Since Na, Cl, phosphorus (P), and sulfur (S) are nutrients for plant growth, the silica particles further containing the above elements or compounds as sub-components tends to be advantageous for plant growth. The silica particles may contain Na, Cl, P within a range that can obtain the effects of the culture soil of the present disclosure. ２ O ５ , S.O. ３ It is not necessary to include any of the above.

[0027] The silica particles may be secondary particles formed by agglomeration of multiple primary particles, or tertiary particles formed by agglomeration of secondary particles. That is, the silica particles may be agglomerated particles. The silica particles may also contain non-agglomerated primary particles. The average particle size of the primary particles may be, for example, 50 nm or less, 1 nm or more to 50 nm or less, or 10 nm or more to 40 nm or less. The average particle size of the primary particles may be, for example, 1 nm or more, or 10 nm or more. Whether the silica particles are agglomerated particles can be confirmed by the following procedure. First, the silica particles are immersed in an alkaline solution for 5 days. The alkaline solution may be a strong alkaline solution. Then, the surface or cross section of the silica particles removed from the alkaline solution is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) to confirm the presence of a primary particle or a boundary between multiple primary particles.

[0028] The silica particles may contain silica mother particles (hereinafter also referred to as mother particles) having a particle size of 100 nm or more. The central particle size of the mother particles may be 120 nm or more and 800 nm or less in the particle size distribution of the mother particles. The "central particle size" refers to the median value of particle sizes in the particle size distribution. In other words, the "central particle size" is the so-called median diameter (D50). In this specification, the particle size distribution of the mother particles is the particle size distribution calculated from the longest diameter measured for 25 or more particles (mother particles) having a particle size of 100 nm or more in an SEM image of the silica particles at 50,000 magnification, and the central particle size of the mother particles is the median value calculated from the particle size distribution. Furthermore, the mother particles may be secondary particles or tertiary particles.

[0029] The silica particles may further contain silica fine particles (hereinafter also referred to as fine particles) having a particle size of less than 100 nm. When the silica particles further contain fine particles, the median particle size of the fine particles may be 10 nm or more and less than 100 nm in the particle size distribution of the fine particles. In this specification, the particle size distribution of the fine particles is a particle size distribution calculated from the longest diameter measured for 25 or more particles (fine particles) having a particle size of less than 100 nm in an SEM image of the silica particles at 200,000 magnification, and the median particle size of the fine particles is the median calculated from the particle size distribution. In addition, the fine particles may be secondary particles or tertiary particles.

[0030] The silica particles may include both base particles and fine particles, or may include only base particles.

[0031] One or more fine particles may be attached to the outer surface of the base particle. In this specification, "attached" refers to the state in which the silica particles and the base particle are integrated to such an extent that the fine particles do not fall off when water is poured over the silica particles. Specifically, a chemical bond such as a covalent bond may exist between the fine particles and the base particle.

[0032] The silica particles may contain water-soluble silica, which is a water-soluble component. When water-soluble silica dissolves in water, it becomes silicic acid. The silicic acid is orthosilicic acid (H ４ SiO ４ ), metasilicic acid (H ２ SiO ３ In soil, silicic acid is a compound that is water-soluble and contains SiOH, such as calcium silicate (Ca ２ SiO ４ These silicates are also called available silicates, and can be absorbed by plants to promote plant growth.

[0033] The content of available silicic acid in silica particles is not particularly limited and may be 0 g / 100 g or more and 100 g / 100 g or less. The content of available silicic acid in silica particles is measured, for example, in accordance with the method described in "Soil, Water Quality and Plant Analysis Method" (Japan Soil Association, 2001). The content of available silicic acid in silica particles can be measured, for example, by the molybdenum blue method after extraction with a pH 6.2 phosphoric acid extract.

[0034] The silica particles are not particularly limited and commercially available silica particles or the like can be used, but it is preferable to use silica particles having the structure described below (hereinafter referred to as silica particles A).

[0035] (Silica Particles A) Silica particles A contain silica mother particles having a particle size of 100 nm or more. The content of the mother particles in silica particles A (when the mother particles have fine particles described below, the content of the mother particles having fine particles) may be, for example, 40 mass % or more, 60 mass % or more, 80 mass % or more, 90 mass % or more, 95 mass % or more, or 100 mass %. The median particle size of the mother particles is 120 nm or more and 800 nm or less in the particle size distribution of the mother particles.

[0036] The silica particles A may further contain silica fine particles having a particle size of less than 100 nm. When the silica particles A further contain fine particles, the median particle size of the fine particles is 10 nm or more and less than 100 nm in the particle size distribution of the fine particles.

[0037] The silica particles A may have fine particles on the surface of the base particle. The base particle may have a plurality of fine particles. The presence of fine particles on the surface of the base particle tends to increase the specific surface area of ​​the silica particles A. The silica particles A may include at least one of base particles having a plurality of fine particles and base particles having no fine particles, may include only base particles having a plurality of fine particles and base particles having no fine particles, or may include only base particles having a plurality of fine particles or base particles having no fine particles. The presence of fine particles in the base particle can be confirmed, for example, by observation at 200,000 magnification with an SEM.

[0038] When the silica particles A contain fine particles, the fine particles may be attached to most or all of the base particles. When the fine particles are attached to the outer surfaces of the base particles, the contact area of ​​the silica particles A as a whole with the soil tends to be large, and as a result, plant growth due to the silica particles A tends to be improved.

[0039] The base particles of silica particles A may have voids therein. The fine particles of silica particles A may also have voids therein. When the porosity of a single particle is defined as the ratio of the area occupied by voids in the cross section of a single silica particle A to the cross-sectional area of ​​the single silica particle A, the porosity of a single particle may be, for example, 0.2% to 6.0%, or 2.5% to 6.0%, or 0.2% to 2.0%, for example, 1.2%. The void ratio of the base particle may be less than 0.2% or more than 6.0%. The porosity of a single particle can also be measured, for example, by analyzing images captured by TEM.

[0040] The mother particles of the silica particles A may be secondary particles (aggregated particles) composed of a plurality of primary particles. Furthermore, the fine particles of the silica particles A may be secondary particles (aggregated particles) composed of a plurality of primary particles. The average particle size of the primary particles may be, for example, 50 nm or less, 1 nm or more to 50 nm or less, or 10 nm or more to 40 nm or less. Furthermore, the average particle size of the primary particles may be, for example, 1 nm or more, or 10 nm or more.

[0041] The base particles of silica particles A may have cracks. The term "cracks" refers to linear images on the surface of the base particles observed in an SEM image at 150,000 magnifications. The cracks may be groove-like depressions, linear scratches, steps, etc., formed on the surface of the base particles.

[0042] The specific surface area of ​​the silica particles A is, for example, 15 m ２ / g or more 200m ２ / g or less, and ２ / g. The specific surface area is the value of the surface area per unit weight. The specific surface area of ​​silica particles A is measured, for example, by a gas adsorption measurement method (BET method) using the BET method. The BET method is a method for measuring the surface area of ​​particles by adsorbing a gas with a known adsorption occupation area onto the surface of the particles. The specific surface area of ​​silica particles A is 15 m within the range in which the effect of the culture soil of the present disclosure can be obtained. ２ / g or less than 200m ２ / g or more.

[0043] The silica particles A may be amorphous. The crystallinity of the silica particles A is confirmed by X-ray diffraction (XRD). Both the base particles and the fine particles may be amorphous.

[0044] The coefficient of variation of the silica particles A may be, for example, 0.30 or less. The coefficient of variation is the value obtained by dividing the standard deviation of the particle size of the silica particles A by the average particle size of the silica particles A. The coefficient of variation may be greater than 0.30 within a range in which the effects of the culture soil of the present disclosure can be obtained.

[0045] The silica particles A do not contain particles having a particle size of less than 100 nm other than the mother particles and the fine particles contained in the mother particles, or even if they do, the amount of particles is very small compared to the amount of the mother particles. When the silica particles A contain particles having a particle size of less than 100 nm, the number of particles having a particle size of less than 100 nm may be 1 / 100 or less of the number of the mother particles.

[0046] Silica particles A are SiO ２ The base particles and fine particles of the silica particles A may be particles containing SiO as a main component. ２ It may be.

[0047] Silica particles A are C, P ２ O ５ , S.O. ３ The silica particles A may further contain, as a secondary component, one or more elements or compounds selected from Na, Cl, P, and Cl, as long as the effects of the culture soil of the present disclosure can be obtained. ２ O ５ , S.O. ３The content may not necessarily be any of the above, and is not limited to the examples of the content shown below.

[0048] When silica particles A contain C, the content of C in silica particles A may be, for example, 5.0 mass% or less, 1.5 mass% or more, or even 1.5 mass%. The content of C in silica particles A can be measured using a carbon / sulfur analyzer (CS analyzer). In carbon measurement using a CS analyzer, silica particles A are dissolved in a high-frequency heating furnace in an oxygen stream. At this time, the C component contained in silica particles A is dissolved in CO, CO ２ The carbon-derived gas is then measured using an infrared detector. This quantifies the amount of C contained in the silica particles A. From the quantification results, the C content in the silica particles A is calculated. The C content in the silica particles A may be less than 1.5% by mass or more than 5.0% by mass, as long as the effects of the culture soil of the present disclosure are obtained.

[0049] Silica particles A are P ２ O ５ When the silica particles A contain ２ O ５ The content of the silica particles A may be, for example, 0.1% by mass or less, or may be 0.01% by mass. ３ When the silica particles A contain ３ The content of may be, for example, 0.1% by mass or less, or may be 0.04% by mass. When the silica particles A contain Cl, the content of Cl in the silica particles A may be, for example, 0.05% by mass or less, or may be 0.02% by mass. When the silica particles A contain Na, the content of Na in the silica particles A may be, for example, less than 0.01% by mass, or may be 0.01% by mass or more as long as the effect of the culture soil of the present disclosure is obtained. P in the silica particles A ２ O ５ , S.O. ３ The Cl content is measured by, for example, X-ray fluorescence analysis, and the Na content is measured by, for example, emission spectroscopy.

[0050] When the silica particles A contain N, the N content in the silica particles A may be, for example, 1.0 mass% or less, 0.8 mass% or less, or 0.73 mass% or less. The N content in the silica particles A is measured, for example, by an inert gas fusion method.

[0051] N is ammonia nitrogen (NH ４ In the silica particles A, N may be present as ammonia nitrogen (NH ４ When present as ammonia nitrogen (NH ４ The content of nitrate nitrogen (NO -N) may be, for example, 5.0 mg / 100 g or less, 4.0 mg / 100 g or less, 3.0 mg / 100 g or less, 1.6 mg / 100 g or less, or 1.5 mg / 100 g. ３ The silica particles A may contain nitrate nitrogen (NO 3 -N) for example, less than 0.1 mg / 100 g, or less than 0.05 mg / 100 g. ３ -N). The contents of ammonia nitrogen and nitrate nitrogen in silica particles A are measured, for example, in accordance with the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997). The content of ammonia nitrogen in silica particles A can be measured, for example, by the indophenol method using a potassium chloride solution as the extraction solution. The content of nitrate nitrogen in silica particles A can be measured, for example, by extraction with a potassium chloride solution, followed by alkali reduction, and then by the diazo dye method.

[0052] The base exchange capacity (CEC) (also referred to as fertilizer retention capacity) of the silica particles A may be, for example, 1.0 meq / 100 g or less, 0.6 meq / 100 g or less, or 0.5 meq / 100 g or less. The CEC of the silica particles A is measured, for example, in accordance with the method described in "Soil Environmental Analysis Method" (Soil Environmental Analysis Method Editorial Committee, 1997). The CEC of the silica particles A can be measured, for example, by the indophenol method after extraction by the modified Schollenberger method.

[0053] The silica particles A may be almost insoluble in water or may be insoluble in water. Despite being almost insoluble or insoluble in water, the silica particles A can achieve a higher growth-promoting effect than silicic acid or the like used as a plant growth promoter. Furthermore, despite being almost insoluble or insoluble in water, the silica particles A can improve the growth of plants that require silicon for growth. Therefore, it is presumed that the growth-promoting effect of the silica particles A is not due to the above-mentioned absorption of silicic acid. Furthermore, the silica particles A also have the effect of suppressing insect damage to plants. Although the reasons for these effects are not clear, it is presumed that the silica particles A activate specific useful microorganisms present in the soil.

[0054] The content of available silicic acid in silica particles A may be, for example, 100 mg / 100 g or less, preferably 80 mg / 100 g or less, more preferably 50 mg / 100 g or less, even more preferably 30 mg / 100 g or less, and may even be 0 mg / 100 g. When the content of available silicic acid in silica particles A is within the above range, they tend to be insoluble in water. The content of available silicic acid in silica particles A is measured, for example, in accordance with the method described in "Soil, Water Quality and Plant Analysis Method" (Japan Soil Association, 2001). The content of available silicic acid in silica particles A can be measured, for example, by the molybdenum blue method after extraction with a pH 6.2 phosphoric acid extract.

[0055] The silica particles A can be produced, for example, by using commercially available silica particles. The method for producing the silica particles A can be, for example, a production method (hereinafter also referred to as a first production method) in which silica particles A are produced in the process of producing electronic components, as described below.

[0056] FIG. 3 is an explanatory diagram illustrating an example of a method for producing silica particles A.

[0057] First, in forming the element body, in the laminate preparation step S11, a laminate, which is a rectangular parallelepiped element body, is prepared. For example, first, a plurality of ceramic sheets that will become the element body are prepared. The ceramic sheets may be thin plate-shaped. A conductive paste that will become electrodes and wiring is laminated on the ceramic sheets. A ceramic sheet that will become the element body is laminated on the laminated conductive paste. In this way, the ceramic sheets and the conductive paste are laminated. Then, by cutting to a predetermined size, an unfired laminate is formed. Thereafter, the unfired laminate is fired at a high temperature to prepare the laminate.

[0058] Next, a solvent introduction step S12 is performed. In the solvent introduction step S12, a solvent is introduced into the reaction vessel. The solvent may be any liquid that can disperse the metal alkoxide appropriately, such as 2-propanol.

[0059] Next, a catalyst introduction step S13 is performed. In the catalyst introduction step S13, first, stirring of the solvent in the reaction vessel is started. Then, ammonia water is introduced into the reaction vessel as an aqueous solution containing a catalyst. The catalyst is a hydroxide ion, and functions as a catalyst for promoting the hydrolysis of the metal alkoxide, which will be described later.

[0060] Next, an object introduction step S14 is performed. In the object introduction step S14, a plurality of element bodies formed in advance in the laminate preparation step S11 described above are introduced into the reaction vessel as objects.

[0061] Next, a polymer introduction step S15 is carried out. In the polymer introduction step S15, polyvinylpyrrolidone is introduced into the reaction vessel as a polymer. As a result, the polymer introduced into the reaction vessel is adsorbed onto the outer surface of the element body.

[0062] Next, a metal alkoxide introduction step S16 is performed. In the metal alkoxide introduction step S16, liquid tetraethyl orthosilicate is introduced into the reaction vessel as the metal alkoxide. Note that tetraethyl orthosilicate is also called tetraethoxysilane.

[0063] Next, the film-forming step S17 is performed. In the film-forming step S17, the stirring of the solvent, which began in the solvent-feeding step S12 described above, is continued for a predetermined time after the metal alkoxide is fed into the reaction vessel in the metal alkoxide-feeding step S16. As a result, the metal alkoxide is hydrolyzed by the hydroxide ions serving as a catalyst. When the metal alkoxide is hydrolyzed, the hydrolyzed metal alkoxide adheres to the surface of the element body. Then, the metal alkoxides attached to the surface of the element body dehydrate and condense with each other to form a glass film. Therefore, in the film-forming step S17, a sol-like glass film is formed by a liquid-phase reaction in the reaction vessel. Furthermore, the dehydration and condensation reaction between the metal alkoxides also progresses in the solution. As a result, sol-like silica particles are produced as a by-product.

[0064] Next, an element removal step S18 is performed. In this step, the element is removed from the reaction vessel. The element is then dried and fired to obtain an electronic component having a glass film formed on the outer surface of the element.

[0065] Next, a recovery step S19 is performed. In the recovery step S19, silica particles present in the solution in the reaction vessel are recovered. Specifically, the solvent in the reaction vessel is evaporated to recover the silica particles remaining in the reaction vessel. As described above, this solution contains sol-like silica particles. Note that tetraethyl orthosilicate and polyvinylpyrrolidone adhere to the outer surfaces of the recovered silica particles.

[0066] Next, a drying step S20 is performed. In the drying step S20, the sol-state silica particles recovered in the recovery step S19 are dried. This removes most of the liquid components, such as 2-propanol and water, from the recovered sol-state silica particles. Through this drying step S20, base particles having a particle size of 100 nm or more are generated as silica particles. The median particle size of the generated base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles. The particle size of the generated base particles can be controlled, for example, by adjusting the time of the film-forming step S17.

[0067] Next, the baking step S21 is performed. In the baking step S21, the silica particles that have undergone the drying step S20 are baked at a temperature of 300°C to 450°C for 5 to 40 minutes. Specifically, the baking is performed at a temperature of 400°C for 30 minutes. As a result, the gel-like silica particles contained in the solution harden as the moisture and polymer evaporate. Through this baking step S21, fine particles with a particle size of less than 100 nm are generated as silica particles. The median particle size of the generated fine particles is 10 nm to 100 nm in the particle size distribution of the fine particles. Furthermore, the generated fine particles that are in contact with the base particles are sintered together with the base particles during the baking step S21. Therefore, the fine particles adhere to the surface of the base particles. The particle size of the generated silica fine particles can be controlled by adjusting the baking temperature and time in the baking step S21. In this manner, silica particles A are produced, which include base particles having a median particle size of 120 nm or more and 800 nm or less and fine particles having a median particle size of 10 nm or more and less than 100 nm.

[0068] As described above, the silica particles A can be produced using a solution containing silica particles, which is an industrial by-product. This eliminates the need to dispose of the solution containing silica particles, and is environmentally friendly because it reduces the energy consumed for the disposal.

[0069] The silica particles A may be produced during the process of forming a glass film on an object, and may not be produced during the process of manufacturing an electronic component. In other words, the object introduced into the reaction vessel in the object introduction step S14 does not have to be an element body of an electronic component.

[0070] The solvent introduction step S12 may be performed after the catalyst introduction step S13 or the object introduction step S14. The solvent introduction step S12 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13. The solvent introduction step S12 may also be omitted. In this case, for example, if the amount of water contained in the aqueous solution containing the catalyst is appropriately large, the metal alkoxide will react in the liquid phase. Alternatively, the aqueous solution containing the catalyst may be introduced in a state where it is mixed with an organic solvent as a solvent.

[0071] Although the catalyst has been described as being added as an aqueous solution containing the catalyst, a solid compound containing the catalyst and water may be added separately to the reaction vessel, in which case the catalyst can be considered to have been added to the reaction vessel when it is produced in the reaction vessel. Alternatively, for example, a solid compound containing the catalyst may be added to the reaction vessel, and moisture in the air may be used as the water required for hydrolysis.

[0072] The object introduction step S14 may be performed before the catalyst introduction step S13. Furthermore, when the object introduction step S14 is performed before the catalyst introduction step S13, the metal alkoxide introduction step S16 may be performed before the catalyst introduction step S13 or the object introduction step S14. The object introduction step S14 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13.

[0073] In the metal alkoxide introduction step S16, the metal alkoxide may be generated in the reaction vessel, instead of being introduced into the reaction vessel after being generated outside the reaction vessel. For example, the metal alkoxide may be generated by reacting a metal salt with an alcohol. Therefore, even when a metal salt and an alcohol, which are metal alkoxide precursors, are introduced into the reaction vessel and reacted to generate the metal alkoxide, the metal alkoxide can be considered to have been introduced into the reaction vessel.

[0074] The metal alkoxide is not limited to tetraethyl orthosilicate. The alkoxy group of the metal alkoxide may be a methoxy group, a propoxy group, or the like, or may be modified with a functional group such as a long-chain alkyl group or an epoxy group, as in a coupling agent. Furthermore, the coordination number for the metal contained in the metal alkoxide is not limited to tetracoordination, but may be 3 or 2.

[0075] The element removal step S18 may be omitted. That is, the recovery step S19 may be performed while the element remains in the reaction vessel.

[0076] In the calcination step S21, the temperature at which the sol- or gel-like particles are calcined may be less than 300° C. or more than 450° C. The calcination time may be less than 5 minutes or more than 40 minutes. For example, even if the temperature is higher than 450° C., calcination for less than 5 minutes may be sufficient as long as silica particles having a median particle size of 120 nm to 800 nm can be produced.

[0077] In the recovery step S19, the silica particles may be recovered by, for example, evaporating the solvent by drying under reduced pressure. The particle size of the base particles of the silica particles generated in the drying step S20 and the firing step S21 may be controlled by the concentration of the materials in each step.

[0078] The base particles of silica particles A may be multilayer particles having a core portion and an outer layer. Base particles that are multilayer particles are also referred to as multilayer base particles. The core portion is approximately spherical and includes the center of gravity of the silica particle A. The core portion may have an internal void. The outer layer is a portion that covers the core portion from the outside and includes the outer surface of the base particle. The base particle has an outer layer on the surface side including the outer surface. The silica particles A may contain polyvinylpyrrolidone. When the silica particles A contain polyvinylpyrrolidone, the outer layer may contain polyvinylpyrrolidone. When the outer layer contains polyvinylpyrrolidone, the concentration of polyvinylpyrrolidone is higher than the concentration of polyvinylpyrrolidone in the portion of the silica particles A excluding the outer layer, i.e., the core portion. Furthermore, when the silica particles A are imaged using, for example, a field emission transmission electron microscope (FE-TEM), a substantially clear interface may be observed between the outer layer and the portion excluding the outer layer. The multilayer base particle may or may not contain fine particles.

[0079] The ratio of the thickness T of the outer layer to the particle diameter D of the base particles (also referred to as the T / D ratio) may be, for example, 2% or more. For example, when the particle diameter D of the base particles is approximately 260 nm and the thickness T of the outer layer is approximately 15 nm, the T / D ratio is approximately 5.8%. Polyvinylpyrrolidone has various properties, such as high hygroscopicity and viscosity increasing properties. Therefore, when the outer layer contains polyvinylpyrrolidone, it tends to be more effective in promoting plant growth, such as preventing soil from drying out and sustained release of active ingredients.

[0080] The thickness T of the outer layer is defined as follows. First, an image of the base particle is taken using an FE-TEM or the like. In the image, the dimension of the outer layer at an arbitrary point on the outer surface of the base particle in a direction perpendicular to the outer surface is defined as the thickness T of the outer layer at that point. More specifically, "the direction perpendicular to the outer surface at an arbitrary point on the outer surface of the base particle" refers to the direction perpendicular to a tangent line drawn to the base particle with the arbitrary point as the contact point. The thickness of the outer layer is the distance from the arbitrary point to the interface in the perpendicular direction.

[0081] The multilayer base particles are produced, for example, by recovering silica particles from the solution after carrying out the steps from the laminate preparation step S11 to the drying step S20 in the first production method. That is, the multilayer base particles can be silica particles after carrying out the drying step S20 and before carrying out the firing step S21 in the first production method.

[0082] In addition, the concentration of polyvinylpyrrolidone in the outer layer of the silica particles A may be equal to or less than the concentration of polyvinylpyrrolidone in the core portion. In addition, the ratio of the thickness T of the outer layer to the particle diameter D of the silica particles A may be less than 2%. Even in these cases, the effects of the culture soil of the present disclosure can be obtained.

[0083] The base particles may have a T / D ratio of less than 2% or may not have an outer layer, i.e., the silica particles A may have no clear boundary between the core and the outer layer.

[0084] The silica particles A may include both base particles without a multilayer structure and multilayer base particles. In other words, the silica particles A may include both silica particles after the firing step S21 and silica particles after the drying step S20 that have not been subjected to the firing step S21.

[0085] [Method for Growing Plants Using Culture Soil] The method for growing plants using culture soil according to the first embodiment includes a step of planting plants in the upper layer 11 of the first culture soil.

[0086] As shown in FIG. 1 , a plant is planted in the upper layer 11 of the first culture soil. Planting refers to planting a plant to be grown, and includes sowing seeds and planting seedlings. When sowing plant seeds in the upper layer 11, planting refers to sowing the seeds within the area of ​​the upper layer 11. When planting plant seedlings in the upper layer 11, planting refers to planting the plant so that the entire roots are present within the area of ​​the upper layer 11 (see FIG. 1 ). More specifically, "planting a plant in the upper layer 11" refers to planting the plant so that the seeds and roots do not come into contact with the lower layer 12. The upper layer 11 has a high concentration of silica particles, which promotes the growth of the planted plant. When at least a portion of the roots of the grown plant reach the lower layer 12, the growth of the plant is suppressed compared to the upper layer 11. Therefore, for example, a growth method can be realized in which a plant is grown quickly to a desired growth amount and then its growth is slowed down. In other words, a growth method that can control the growth amount and growth rate of a plant is provided. Such an effect can be suitably used, for example, as a method for preventing leggy growth of rice, grass, flowers, etc.

[0087] The position where the plant is planted can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, near the center of the upper layer 11 in the thickness direction.

[0088] The thickness of the upper layer 11 can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, 1 cm or more and 50 cm or less.

[0089] The thickness of the lower layer 12 can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, 1 cm or more and 50 cm or less.

[0090] Second Embodiment Hereinafter, the culture soil according to the second embodiment and the method for growing plants using the same will be described, focusing mainly on the differences from the first embodiment.

[0091] [Culture soil] In the culture soil according to the second embodiment (hereinafter also referred to as the second culture soil), the concentration of silica particles in the upper layer 11 is lower than that in the lower layer 12. Therefore, in the upper layer 11, where the concentration of silica particles is low, the growth-promoting effect is suppressed compared to the lower layer 12. On the other hand, in the lower layer 12, where the concentration of silica particles is high, a higher growth-promoting effect is obtained. This makes it possible to control, for example, the amount and growth rate of plants.

[0092] The type of soil constituting the second culture medium is not particularly limited as long as it is suitable for plant growth. The soil constituting the upper layer 11 and the soil constituting the lower layer 12 may be the same soil or different soils.

[0093] The concentration of silica particles in the second culture medium can be expressed, for example, as the amount of silica particles per 100 g of culture medium. The amount of silica particles in the culture medium can be calculated by the measurement method described below.

[0094] The concentration of silica particles in the upper layer 11 can be expressed as the amount of silica particles per 100 g of the culture medium constituting the upper layer 11. The concentration of silica particles in the upper layer 11 in the second culture medium may be, for example, 10 mg / 100 g or less, preferably 5 mg / 100 g or less, more preferably 3 mg / 100 g or less, even more preferably 1 mg / 100 g or less, or may be 0 mg / 100 g.

[0095] The concentration of silica particles in the lower layer 12 can be expressed as the amount of silica particles per 100 g of the culture medium constituting the lower layer 12. The concentration of silica particles in the lower layer 12 in the second culture medium may be, for example, 20 mg / 100 g or more, preferably 50 mg / 100 g or more, more preferably 70 mg / 100 g or more, and even more preferably 100 mg / 100 g or more. The concentration of silica particles in the lower layer 12 in the second culture medium may be, for example, less than 100 g / 100 g.

[0096] By setting the silica particle concentration in the upper layer 11 and the silica particle concentration in the lower layer 12 within the above ranges, plant growth can be more effectively suppressed in the upper layer 11 and more effectively promoted in the lower layer 12, making it possible to control the amount and rate of plant growth.

[0097] The second culture medium can be produced, for example, by preparing two types of culture medium with different concentrations of silica particles and layering the culture medium with a lower concentration of silica particles on top of the culture medium with a higher concentration of silica particles.

[0098] As the silica particles constituting the second culture soil, the same silica particles as those in the first embodiment can be used, and it is preferable to use silica particles A.

[0099] [Method for Growing Plants Using Culture Soil] The method for growing plants using culture soil according to the second embodiment includes a step of planting plants in the upper layer 11 of the second culture soil.

[0100] As shown in FIG. 1 , plants are planted in the upper layer 11 of the second culture soil. Planting refers to planting a plant to be grown, and includes sowing seeds and planting seedlings. When sowing plant seeds in the upper layer 11, planting refers to sowing seeds within the area of ​​the upper layer 11. When planting plant seedlings in the upper layer 11, planting refers to planting the plant so that the entire roots are present within the area of ​​the upper layer 11 (see FIG. 1 ). More specifically, "planting a plant in the upper layer 11" refers to planting the plant so that the seeds and roots do not come into contact with the lower layer 12. Because the upper layer 11 has a low concentration of silica particles, the growth of the planted plant is not promoted and the growth rate tends to be relatively slow. When at least a portion of the roots of the grown plant reach the lower layer 12, the plant's growth is promoted compared to the upper layer 11. Therefore, for example, a method for growing plants can be realized in which growth is suppressed in the early stages and then promoted from a desired stage. That is, a method for growing plants that can control the amount and rate of growth of plants is provided.

[0101] The position where the plant is planted can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, near the center of the upper layer 11 in the thickness direction.

[0102] The thickness of the upper layer 11 can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, 1 cm or more and 50 cm or less.

[0103] The thickness of the lower layer 12 can be adjusted as appropriate depending on the type of plant and the desired amount and rate of growth, but may be, for example, between 1 cm and 50 cm.

[0104] Third Embodiment A third embodiment of the plant growing method will now be described.

[0105] A plant growing method according to a third embodiment includes the steps of raising plants in a culture medium containing a mixture of soil and silica particles, and transplanting the seedlings obtained in the raising step into soil. Specifically, as shown on the left side of FIG. 2 , plants are planted in a seedling raising container filled with a culture medium containing a mixture of soil and silica particles, and the plants are raised for a predetermined period of time. "Planting" refers to planting the target plant and includes sowing seeds and planting seedlings. Next, as shown in the center of FIG. 2 , the raised seedlings are transplanted into a container filled with another soil. The right side of FIG. 2 shows the further growth of the transplanted seedlings.

[0106] In the process of raising plants in a culture medium in which soil and silica particles are mixed (hereinafter also referred to as silica-mixed soil), the silica-mixed soil is first prepared or produced.

[0107] The soil and silica particles constituting the silica-mixed soil can be the same as those in the first embodiment. The silica particles constituting the silica-mixed soil are preferably silica particles A. The silica-mixed soil is composed of a single layer in which the concentration of silica particles is uniform or approximately uniform throughout. The concentration of silica particles in the silica-mixed soil may be, for example, 20 mg / 100 g or more, preferably 50 mg / 100 g or more, more preferably 70 mg / 100 g or more, and even more preferably 100 mg / 100 g or more. The concentration of silica particles in the silica-mixed soil may be, for example, less than 100 g / 100 g.

[0108] Next, plants are planted in the seedling containers containing the silica-mixed soil. The seedling containers are containers for growing plant seedlings, such as seedling pots, plug trays, and planters. The planted seedlings are grown for a predetermined period of time.

[0109] Next, a step of transplanting the seedlings obtained in the seedling raising step into soil is carried out. After a predetermined seedling raising period has elapsed, the seedlings grown in the seedling raising step are transplanted into soil. The soil after transplantation is preferably soil without silica particles mixed therein. The concentration of silica particles in the soil after transplantation may be, for example, 10 mg / 100 g or less, preferably 5 mg / 100 g or less, more preferably 3 mg / 100 g or less, even more preferably 1 mg / 100 g or less, and may even be 0 mg / 100 g.

[0110] The seedlings obtained in the seedling raising step may be transplanted into small containers such as seedling raising containers, or into large planters or fields.

[0111] The seedlings obtained in the raising step may be transplanted with the root ball, or the root ball may be broken and then transplanted. When the root ball is transplanted, a culture medium having different concentrations of silica particles is formed in the root ball area and the area other than the root ball, so the same effect as in the first embodiment can be expected. Note that Fig. 2 shows an embodiment in which the seedlings obtained in the raising step are transplanted with the root ball, but the present invention is not limited to this.

[0112] In the seedling raising process, using silica-mixed soil can promote seedling growth and shorten the seedling raising period. After the seedlings have grown, they can be transplanted into soil with a suppressed growth-promoting effect, preventing excessive seedling growth. As a result, a growing method can be realized in which, for example, productivity is increased by growing the seedlings early before shipping, and spindly growth is prevented or suppressed when the seedlings are sold in stores or after they are purchased by consumers.

[0113] Fourth Embodiment Hereinafter, a fourth embodiment of the plant growing method will be described, focusing mainly on the differences from the third embodiment.

[0114] A plant growing method according to a fourth embodiment includes a step of raising plants in soil and a step of transplanting the seedlings obtained in the raising step into a culture medium containing a mixture of soil and silica particles. Specifically, as shown on the left side of FIG. 2 , the plants are planted in a seedling raising container filled with soil and raised for a predetermined period of time. Planting refers to planting the target plant and includes sowing seeds and planting seedlings. Next, as shown in the center of FIG. 2 , the raised seedlings are transplanted into a container filled with a culture medium containing a mixture of soil and silica particles. The right side of FIG. 2 shows the further growth of the transplanted seedlings.

[0115] In the step of raising plants in soil, the plants are planted in a seedling container containing the soil. Preferably, the soil does not contain silica particles. The concentration of silica particles in the soil may be, for example, 10 mg / 100 g or less, preferably 5 mg / 100 g or less, more preferably 3 mg / 100 g or less, and even more preferably 1 mg / 100 g or less, or even 0 mg / 100 g.

[0116] Next, the seedlings obtained in the seedling raising step are transplanted into silica-mixed soil. After a predetermined seedling raising period has elapsed, the grown seedlings are transplanted into the silica-mixed soil. The concentration of silica particles in the silica-mixed soil may be, for example, 20 mg / 100 g or more, preferably 50 mg / 100 g or more, more preferably 70 mg / 100 g or more, and even more preferably 100 mg / 100 g or more. The concentration of silica particles in the silica-mixed soil may be, for example, less than 100 g / 100 g.

[0117] The seedlings obtained in the seedling raising step may be transplanted with the root ball, or the root ball may be broken up and transplanted. When transplanted with the root ball, a culture medium with different concentrations of silica particles is formed in the area around the root ball and the area outside the root ball, and the same effect as in the second embodiment is expected.

[0118] In the seedling raising process, using soil with suppressed growth-promoting effects can prevent excessive growth during the seedling raising period. After the seedlings have grown, they can be transplanted into silica-mixed soil to promote their growth. As a result, a growing method can be realized in which excessive growth in seedling containers is prevented when raising seedlings before shipping or when selling them in stores, and rapid growth is promoted after transplanting to large fields or after purchase by consumers.

[0119] Hereinafter, the present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to these.

[0120] [Production of Silica Particles] A plurality of laminates each consisting of a plurality of ceramic sheets were prepared. 2-Propanol was added as a solvent to a reaction vessel, and stirring was initiated. Next, ammonia water, the plurality of laminates, polyvinylpyrrolidone, and tetraethoxysilane were added, in that order, to the reaction vessel. After a predetermined time had passed, the plurality of laminates were removed. Sol-state silica particles were recovered by evaporating the solvent from the solution in the reaction vessel. The recovered sol-state silica particles were further dried to obtain silica particles. The obtained silica particles were calcined at 400°C for 30 minutes. The calcined silica particles were used as silica particles A.

[0121] FIG. 4 is an image of silica particles A observed with an SEM at a magnification of 50,000 times. FIG. 5 is an image of silica particles A observed with an SEM at a magnification of 250,000 times. Silica particles A contained mother particles and microparticles, with a plurality of microparticles attached to the outer surfaces of the mother particles. The median particle size of the mother particles of silica particles A was 251 nm in the particle size distribution of the mother particles. The median particle size of the microparticles of silica particles A was 16 nm. The particle size distributions of the mother particles and microparticles were determined as follows in the SEM images of silica particles A observed at 50,000 times and 200,000 times. First, the particle size distribution was determined from the longest diameters measured for 25 or more mother particles and microparticles in each SEM image. Next, the median values ​​of the determined particle size distributions were determined and used as the median particle sizes of the mother particles and microparticles. The crystallinity of silica particles A was confirmed to be amorphous by X-ray diffraction (XRD).

[0122] The specific surface area of ​​the obtained silica particles measured by the BET method is 163 m ２ The specific surface area of ​​the particles after drying and before calcination was 18.3 m2 by the BET method. ２ / g.

[0123] Silica particles A were immersed in a strong alkaline solution for 5 days, and the surfaces or cross sections of the silica particles A taken out of the alkaline solution were observed by SEM. The presence of multiple primary particle boundaries was confirmed in the mother particles and fine particles of silica particles A. The sizes of two of the multiple primary particles were measured in the SEM observation image and were found to be 26 nm and 29 nm.

[0124] The results of component analysis of silica particles A were as follows. Note that no heavy metals (arsenic, lead, cadmium, mercury, chromium, cyanide) were detected in silica particles A. SiO ２ : More than 99% by mass (X-ray fluorescence analysis) C: 1.5% by mass (CS meter) N: 0.73% by mass (inert gas fusion method) P ２ O ５ : 0.01 mass% (X-ray fluorescence analysis) SO ３ : 0.04% by mass (X-ray fluorescence analysis) Cl: 0.02% by mass (X-ray fluorescence analysis) Na: less than 0.01% by mass (emission spectroscopy) CEC: 0.5 meq / 100 g (indophenol method) Nitrate nitrogen: 0.0 mg / 100 g (diazo dye method) Ammonia nitrogen: 1.5 mg / 100 g (indophenol method) Available silicic acid: 25.8 mg / 100 g (molybdenum blue method)

[0125] Example 1: A mixture of Akadama soil, Kanuma soil, compost, and cocoyuki soil (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a planter while tapping the surface to remove air. As shown in Figure 6, holes 4 cm deep from the soil surface were drilled along the center of the planter. 6.5 g of silica particles A per 25 L of soil was added to the holes. While the soil was being returned, the silica particles A and the soil were mixed within 4 cm of the soil surface. This resulted in a culture medium in which the silica particle concentration in the upper layer (within 4 cm of the soil surface) was higher than that in the lower layer (below 4 cm of the soil surface). Next, as shown in Figure 7, 16 holes 2 cm deep from the culture medium surface were drilled. Two grass seeds were placed in each hole, and the culture medium was returned. 1 L of water was sprayed to initiate growth. The grass height was measured at predetermined intervals.

[0126] Comparative Example 1: A soil mixture of Akadama soil, Kanuma soil, compost, and cocoyuki (manufactured by Togawa Heiwa Farm Co., Ltd.) was uniformly mixed with 6.5 g of silica particles A per 25 L of soil to prepare a culture medium with a uniform silica particle concentration throughout. This culture medium was placed in a planter while tapping the surface to remove air. Sixteen holes were drilled, each 2 cm deep from the surface of the culture medium. Two grass seeds were placed in each hole, and the culture medium was replaced. 1 L of water was sprayed to start growth. The grass height was measured at predetermined intervals.

[0127] Comparative Example 2 Grass growth was initiated in the same manner as in Comparative Example 1, except that silica particles A were not mixed in. The grass height was measured at predetermined intervals.

[0128] The results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in Figures 8 and 9. In Comparative Example 1, the grass growth rate was always high, so the grass continued to grow rapidly even after reaching the desired height. In Comparative Example 2, the grass growth rate was always low, so the growth period until the desired height was reached was long. In Example 1, the grass growth rate was high initially, but the growth rate slowed down halfway through. This shortened the growth period until the desired height was reached, and it was possible to suppress grass growth after the desired height was reached. As a result, the frequency of mowing, aeration, etc. can be reduced.

[0129] (Comparative Example 3) A mixture of Akadama soil, Kanuma soil, compost, and cocoyuki soil (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a plug tray (4 cm x 4 cm x 4.9 cm, 72 holes). 0.02 g of silica particles A was added to each hole in the plug tray and mixed thoroughly. This resulted in the preparation of a culture medium with a uniform silica particle concentration throughout. Next, holes were drilled 2 cm deep from the surface of the culture medium. Two spinach seeds were placed in each hole, and the culture medium was replaced. 1 L of water was sprayed to initiate growth. 100 mL of pure water was sprayed daily, and the growth status was observed.

[0130] Comparative Example 4 The growth state was observed in the same manner as in Comparative Example 3, except that the silica particles A were not mixed.

[0131] The growth results for Comparative Examples 3 and 4 are shown in Figure 10. In Comparative Example 3, the seedlings were grown in a culture medium containing silica particles A, resulting in a high germination rate and rapid seedling growth. However, when the seedlings were left in the culture medium after growth, they did not grow and their leaves turned yellow. In Comparative Example 4, the germination rate was low and the seedlings grew slowly, resulting in a significantly longer seedling raising period. From these results, it is considered preferable to transplant the seedlings into soil that does not contain silica particles after growing them in a culture medium containing a mixture of soil and silica particles.

[0132] Example 2: Commercially available cherry tomato seedlings were grown in seedling pots for two months. The soil used for the commercially available cherry tomato seedlings did not contain silica particles A. The number of cherry tomatoes that fruited in the seedling pots during the two-month seedling period was counted. Meanwhile, soil (manufactured by Togawa Heiwa Farm Co., Ltd.) containing a mixture of Akadama soil, Kanuma soil, compost, and cocoyuki was placed in a planter after tapping to remove air. As shown in Figure 11 , a hole 9 cm deep from the soil surface was drilled along the center of the planter. 6.5 g of silica particles A per 25 L of soil was added to the hole. By mixing the entire soil and silica particles A in the planter while returning the soil, a culture medium with a uniform silica particle concentration was prepared. Next, a hole 15 cm deep from the soil surface was drilled, and the cherry tomato seedlings after the seedling period, including the root ball, were transplanted, as shown in Figure 12 . As a result, a culture medium was prepared in which the concentration of silica particles in the upper layer (the root ball area of ​​the seedling) was lower than that in the lower layer (below the root ball area of ​​the seedling). 1 L of water was sprayed and growth was initiated. 38 days after the start of growth, 2 L of a 500x diluted solution of Biol and 2 L of a 1000x diluted solution of Arafesta were sprayed.

[0133] Comparative Example 5: A soil mixture (manufactured by Togawa Heiwa Farm Co., Ltd.) containing Akadama soil, Kanuma soil, compost, and cocoyuki was uniformly mixed with 6.5 g of silica particles A per 25 L of soil to prepare a culture medium with a uniform silica particle concentration throughout. Commercially available cherry tomato seedlings were transplanted into the culture medium and grown for two months. The number of cherry tomatoes that fruited in the seedling pots during the two-month period was counted. Next, another culture medium with the same composition as the culture medium was placed in a planter while tapping the surface to remove air. A hole 15 cm deep was drilled from the culture medium surface, and the cherry tomato seedlings, including the root ball, were transplanted after the seedling growth period. One liter of water was sprayed to initiate growth. Thirty-eight days after growth began, 2 L of a 500x diluted solution of Biol and 2 L of a 1000x diluted solution of Arafesta were sprayed.

[0134] (Comparative Example 6) Commercially available cherry tomato seedlings were grown in seedling pots for two months. The soil used for the commercially available cherry tomato seedlings did not contain silica particles A. The number of cherry tomatoes that bore fruit in the seedling pots during the two-month seedling period was counted. A mixture of Akadama soil, Kanuma soil, compost, and cocoyuki soil (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a planter while tapping the soil surface to remove air. A hole 15 cm deep was dug from the soil surface, and the cherry tomato seedlings after the seedling period were transplanted with the root ball. 1 L of water was sprayed to initiate growth. 38 days after the start of growth, 2 L of a 500x diluted solution of Biol and 2 L of a 1000x diluted solution of Arafesta were sprayed.

[0135] For Example 2, Comparative Example 5, and Comparative Example 6, the first to tenth cherry tomatoes produced during the entire growing period, including the seedling raising period, were harvested. Using 10 cherry tomatoes, the sugar content was measured using the Abbe refractometer method, and the citric acid content was measured using high-performance liquid chromatography. The amount of silica particles (amount of insoluble silica particles) in the culture soil was calculated using the following measurement method. The root ball portion of the seedling was defined as the upper layer, and the area below the root ball portion of the seedling was defined as the lower layer. The results are shown in Figure 13.

[0136] [Amount of Silica Particles in Culture Soil] First, the amount of available silicic acid in the culture soil is measured. Available silicic acid can be measured by the method described in "Evaluation Method for Available Silica in Paddy Soil by Phosphate Buffer Extraction Method" (Japanese Journal of Soil Science and Plant Nutrition, 2002, Vol. 73, No. 4, pp. 383-390). Next, the silica content in the culture soil was measured. The silica content refers to the SiO2 content including insoluble silica and water-soluble silica (available silicic acid). ２ The silica content refers to the content of all components derived from the soil. The silica content can be calculated by measuring the amount of silica eluted when silica in the soil is eluted with a high concentration of alkali using ICP atomic emission spectroscopy or atomic absorption spectroscopy. The amount of silica particles is determined by subtracting the amount of available silicic acid from the silica content.

[0137] In Example 2, growth was suppressed during the seedling raising period, but growth was promoted after transplanting, resulting in cherry tomatoes with high sugar content and mild acidity from the early stages when the cherry tomatoes began to bear fruit. This result shows that silica particles A have the effect of improving taste. In Comparative Example 5, growth was promoted during the seedling raising period, but nutrients were not distributed evenly within the seedling raising container, resulting in low sugar content and strong acidity in the cherry tomatoes. In Comparative Example 6, silica particles A were not mixed, so the sugar content and citric acid values ​​were inferior to those of Example 2.

[0138] (Reference Example 1) A mixture of Akadama soil, Kanuma soil, compost, and cocoyuki soil (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a planter while tapping the surface to remove air. Sixteen holes were drilled 2 cm deep from the soil surface. Two komatsuna seeds were placed in each hole, and the soil was replaced. 1 L of water was sprayed to start growth.

[0139] (Reference Example 2) A mixture of Akadama soil, Kanuma soil, compost, and cocoyuki soil (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a planter while tapping the surface to remove air. Holes 9 cm deep from the soil surface were drilled along the center of the planter. Silica particles A in an amount of 6.5 g per 25 L of soil were placed in the holes, and the soil was replaced. Next, 16 holes 2 cm deep from the soil surface were drilled. Two komatsuna seeds were placed in each hole, and the soil was replaced. 1 L of water was sprayed to start growth.

[0140] (Reference Example 3) The same procedure as in Reference Example 2 was carried out, except that industrial silica particles ("Seahoster (registered trademark) KE-S50" manufactured by Nippon Shokubai Co., Ltd., average particle size: 0.5 μm) were used instead of silica particles A. No adhesion of fine particles was observed on the surface of the industrial silica particles.

[0141] Reference Example 4 The same procedure as in Reference Example 2 was carried out except that the silica particles A were replaced with a powdered silicate-based activator (T.A. Silicate, manufactured by Terra Aquatica).

[0142] Reference Example 5 was the same as Reference Example 2, except that nanosilica ("CAB-O-SIL (registered trademark) M-5" manufactured by Cabot Corporation) was used instead of silica particles A. The nanosilica was observed by SEM to be fine particles of 10 to 20 nm.

[0143] The growth results for Reference Examples 1 to 5 are shown in Figure 14. Reference Examples 2 and 3 showed good growth results. In Reference Example 2, almost no insect damage was observed compared to Reference Examples 1, 3 to 5. Furthermore, pest infestation was observed on the undersides of the leaves in Reference Examples 1, 3 to 5, but no pests were observed in Reference Example 2. It can be seen that silica particles A function as a pest repellent. Figure 15 shows the results of soil analysis after growth in Reference Examples 1 to 5. Soil analysis was performed according to the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997). The culture soils of Reference Examples 2 and 3 contained relatively high amounts of ammonia nitrogen, while Reference Example 2 contained relatively high amounts of nitrate nitrogen. Nitrate nitrogen is a nitrogen component that has been converted into a form that can be absorbed by plants as a nutrient. Furthermore, ammonia nitrogen is a nitrogen component that is decomposed into nitrate nitrogen by nitrification by microorganisms. Therefore, it is presumed that microbial activity was enhanced in Reference Example 2. As a result, it can be inferred that in Reference Example 2, the activity of microorganisms effective in repelling pests was also increased, resulting in the achievement of a pest repellent effect.

[0144] In the above-described embodiments, configurations that can be combined may be combined with each other.

[0145] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0146] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0147] (Item 1) A culture soil according to an embodiment of the present disclosure includes soil and silica particles. The culture soil has an upper layer and a lower layer. The concentration of silica particles in the upper layer is different from the concentration of silica particles in the lower layer. (Item 2) In the culture soil according to item 1, the silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles. (Item 3) In the culture soil according to item 2, the silica particles further include silica fine particles having a particle size of less than 100 nm. The median particle size of the silica fine particles is 10 nm or more and less than 100 nm in the particle size distribution of the silica fine particles. The silica fine particles are attached to the outer surfaces of the silica base particles. (Item 4) In the culture soil according to any one of items 1 to 3, the concentration of silica particles in the upper layer is higher than the concentration of silica particles in the lower layer. (Item 5) In the culture medium according to any one of Items 1 to 3, the concentration of silica particles in the upper layer is lower than the concentration of silica particles in the lower layer. (Item 6) In another embodiment of the present disclosure, a method for growing plants using culture medium comprises the culture medium containing soil and silica particles. The culture medium has an upper layer and a lower layer. The concentration of silica particles in the upper layer is different from the concentration of silica particles in the lower layer. The method includes planting a plant in the upper layer. (Item 7) In the method for growing plants using culture medium according to Item 6, the silica particles contain silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles. (Item 8) In the method for growing plants using culture medium according to Item 7, the silica particles further contain silica fine particles having a particle size of less than 100 nm. The median particle size of the silica fine particles is 10 nm or more and less than 100 nm in the particle size distribution of the silica fine particles. The silica fine particles adhere to the outer surface of the silica base particles. (Item 9) In the method for growing plants using the culture compost described in any one of Items 6 to 8, the concentration of silica particles in the upper layer is higher than the concentration of silica particles in the lower layer. (Item 10) In the method for growing plants using the culture compost described in any one of Items 6 to 8, the concentration of silica particles in the upper layer is lower than the concentration of silica particles in the lower layer. (Item 11) In the method for growing plants using the culture compost described in any one of Items 6 to 10, the thickness of the upper layer is 15 cm or less.(Item 12) A plant growth method according to yet another embodiment of the present disclosure includes the steps of raising plants in a culture medium containing a mixture of soil and silica particles, and transplanting the seedlings obtained in the raising step into the soil. (Item 13) A plant growth method according to yet another embodiment of the present disclosure includes the steps of raising plants in soil and transplanting the seedlings obtained in the raising step into a culture medium containing a mixture of soil and silica particles. (Item 14) In the plant growth method according to Items 12 or 13, the silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles. (Item 15) In the plant growth method according to Item 14, the silica particles further include silica fine particles having a particle size of less than 100 nm. The median particle size of the silica fine particles is 10 nm or more and less than 100 nm in the particle size distribution of the silica fine particles. The silica fine particles are attached to the outer surfaces of the silica base particles.

[0148] 10 Culture soil, 11 Upper layer, 12 Lower layer, S11 Laminate preparation step, S12 Solvent introduction step, S13 Catalyst introduction step, S14 Object introduction step, S15 Polymer introduction step, S16 Metal alkoxide introduction step, S17 Film formation step, S18 Body removal step, S19 Recovery step, S20 Drying step, S21 Firing step.

Claims

1. A culture medium comprising soil and silica particles, the culture medium having an upper layer and a lower layer, and the concentration of the silica particles in the upper layer being different from the concentration of the silica particles in the lower layer.

2. The culture soil according to claim 1, wherein the silica particles include silica base particles having a particle size of 100 nm or more, and the median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

3. The culture soil according to claim 2, wherein the silica particles further comprise silica microparticles having a particle size of less than 100 nm, the median particle size of the silica microparticles being 10 nm or more and less than 100 nm in the particle size distribution of the silica microparticles, and the silica microparticles are attached to the outer surface of the silica base particles.

4. The culture soil according to any one of claims 1 to 3, wherein the concentration of the silica particles in the upper layer is higher than the concentration of the silica particles in the lower layer.

5. A culture soil according to any one of claims 1 to 3, wherein the concentration of the silica particles in the upper layer is lower than the concentration of the silica particles in the lower layer.

6. A method for growing plants using culture soil, the culture soil containing soil and silica particles, the culture soil having an upper layer and a lower layer, the concentration of the silica particles in the upper layer being different from the concentration of the silica particles in the lower layer, and the method comprising the step of planting the plant in the upper layer.

7. The method of claim 6, wherein the silica particles include silica base particles having a particle size of 100 nm or more, and the median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

8. The method of claim 7, wherein the silica particles further comprise silica microparticles having a particle size of less than 100 nm, the median particle size of the silica microparticles being 10 nm or more and less than 100 nm in the particle size distribution of the silica microparticles, and the silica microparticles are attached to the outer surface of the silica base particle.

9. A growth method according to any one of claims 6 to 8, wherein the concentration of the silica particles in the upper layer is higher than the concentration of the silica particles in the lower layer.

10. A growth method according to any one of claims 6 to 8, wherein the concentration of said silica particles in said upper layer portion is lower than the concentration of said silica particles in said lower layer portion.

11. The method of any one of claims 6 to 10, wherein the thickness of the upper layer is 15 cm or less.

12. A method for growing a plant, comprising: a step of raising the plant in a culture medium containing a mixture of soil and silica particles; and a step of transplanting the seedling obtained in the raising step into soil.

13. A method for growing a plant, comprising: a step of raising the plant in soil; and a step of transplanting the seedling obtained in the raising step into a culture medium containing a mixture of soil and silica particles.

14. A growth method according to claim 12 or 13, wherein the silica particles include silica base particles having a particle size of 100 nm or more, and the median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

15. The method of claim 14, wherein the silica particles further comprise silica microparticles having a particle size of less than 100 nm, the median particle size of the silica microparticles being 10 nm or more and less than 100 nm in the particle size distribution of the silica microparticles, and the silica microparticles are attached to the outer surface of the silica base particle.

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