JP2005314292A - Microbicide and fertilizer for hydroponics, and apparatus for hydroponics using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a method for sterilizing a nutritious liquid at a low cost, facilitating the management thereof and having high sterilizing effects; to provide a sterilizing apparatus in hydroponics of a plant using the method, and a method for the hydroponics; and to provide a method for continuously feeding a silicate ion sterilizing the nutritious liquid and capable of imparting resistivity against the infection with diseases such as mildew to the plant. <P>SOLUTION: The nutritious liquid-sterilizing agent comprises a soluble glass containing 15-60% SiO<SB>2</SB>, 10-40% K<SB>2</SB>O, 0.1-5% Ag<SB>2</SB>O, and 10-50% P<SB>2</SB>O<SB>5</SB>and/or 5-50% B<SB>2</SB>O<SB>3</SB>by mass proportions expressed in terms of oxides. The soluble glass may further contain ≤15% MgO, ≤35% CaO, ≤2% MnO<SB>2</SB>, ≤3% Fe<SB>2</SB>O<SB>3</SB>, ≤1% CuO, ≤1% ZnO and/or ≤1% MoO<SB>3</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to plant hydroponics and relates to sterilization of the nutrient solution and fertilizer.

  Plant hydroponics is a method of cultivating crops using an aqueous solution containing nutrient components necessary for plants without using soil, that is, a nutrient solution. Compared to soil cultivation, there are advantages such as faster growth, higher yield, and less variation in crops. So far, nourishing liquid culture has been mainly the so-called pouring method that drains the used nutrient solution as it is, but the problem of eutrophication of rivers and lakes due to nutrients such as nitrogen contained in the nutrient solution Therefore, a change to circulation type hydroponics that reuses nutrient solution is required.

  Circulation-type hydroponic cultivation has few opportunities for contamination due to soil-borne diseases. On the other hand, unlike soil, there are no antagonists against pathogenic bacteria, so once pathogenic bacteria are mixed into the cultivation bed or culture fluid circulation system. The damage will be very great with the circulation of nutrient solution.

In general, pathogenic bacteria in nutrient solution propagate in the liquid in the form of spores, hyphae, and zoospores, invade from the roots of the plant being cultivated, and cause root rot. In particular, most crops are subject to damage, such as withering and wilt disease caused by Psium, Rhizoctonia, and Fusarium.
Therefore, sterilization of nutrient solution is required, and sterilization and sterilization using agricultural chemicals, ultraviolet rays, ozone, heating, filtration, sterilizing metal ions, and the like are being studied.

  Use of agricultural chemicals for sterilization of nutrient solution is not preferable because residual agricultural chemicals may affect the human body. In addition, it is difficult to obtain a sufficient effect only by ultraviolet rays for sterilization of nutrient solution, and in the case of ozone, there are problems such as complicated maintenance and management of an ozone generator and an expensive device. Sterilization by heating the nutrient solution has a problem of cost and time because a large amount of nutrient solution must be processed. The method of sand filtration of nutrient solution is thought to be controlled by antagonistic microorganisms that settle in the filter, but this is not controlled, so no method has been established.

The following method of adding silver ions or the like as a new sterilization method has also been proposed.
At least one of silver, copper, zinc, and their metal compounds that elute ions having antibacterial performance is used as an antibacterial ion source, and a carrier made of calcium carbonate, calcium phosphate, and ceramic material that adsorbs and carries this antibacterial ion source; There has been reported a hydroponic cultivation apparatus in which an antibacterial and rustproofing agent, which is mainly composed of three crystal tetrapot-shaped three-dimensional zinc oxide whiskers, is installed or mixed (see, for example, Patent Document 1).
Antifungal and antibacterial property-imparting materials in hydroponic cultivation using antifungal and antibacterial property-imparting materials obtained by immersing textiles or polyurethane foam treated with tin chloride in silver nitrate aqueous solution have been reported (for example, Patent Document 2).
A sterilization apparatus for circulation type hydroponic cultivation apparatus using silver impregnated activated carbon has been reported (for example, see Patent Document 3).
The effect of controlling Psium root rot in hydroponic cultivation using silver zeolite has been reported (for example, see Non-Patent Document 1).
Although these are effective, it is necessary to frequently replace the antibacterial ion carrier, and management is complicated.

O Antibacterial glass The thing which knead | dissolved the soluble glass powder containing the silver ion in which the particle size is 50 micrometers or less in the resin fiber raw material is reported (for example, refer patent document 4). This imparts antibacterial properties to the fiber, and there is no disclosure or suggestion about hydroponics.
The Ag ₂ O 0.2 to 5% by weight, ZnO of 1-50% by weight, P ₂ O ₅ 30 to 80 wt%, the CaO 1 to 20% by weight, containing CeO ₂ 0.1 to 5 wt% A soluble glass has been reported (see, for example, Patent Document 5).
Further, a soluble glass containing 20 to 50% by weight of B ₂ O ₃ , 50 to 80% by weight of ZnO, 10% by weight or less of alkaline earth metal oxide, and 2% by weight of Ag ₂ O has been reported. (For example, refer to Patent Document 6).
Further, the ZnO 50-70 mol%, B ₂ O ₃ and / or P ₂ O ₅ 20 to 50 mol%, Al ₂ O ₃ and at least one or more chosen from ZrO ₂ 0.5 to 15 mol% , alkali metal oxide (Na ₂ O) those 5-10 mol% and SiO ₂ which contained 0-20 mole% have been reported (e.g., see Patent Document 7).
These are the compositions of soluble glass, that is, antibacterial glass, and there is no disclosure or suggestion about hydroponics.

Silver oxide (Ag ₂ O) is added to 100 parts by weight of dissolved phosphorus fertilizer having a composition of P ₂ O ₅ : 20.4 wt%, MgO: 15.7 wt%, CaO: 30.0 wt%, SiO ₂ : 26.3 wt%. , Copper oxide (CuO) is blended in a predetermined amount, melted at 1400 ° C. for 10 minutes in an alumina crucible, and then melted and poured into water to rapidly dissolve the glass (for example, Patent Document 8). reference). And as application of this, it is described that it is sprayed in order to impart soil prevention, crop prevention, lawn, planting, prevention of disease or resistance to gardening supplies.

Rice is a silicic acid plant, and silicic acid absorbed by paddy rice has long been well known for its effect of making the rice body strong. In recent years, it has been reported that silicate ions are less likely to be infected with powdery mildew in vegetables such as strawberries (see, for example, Non-Patent Document 2 and Non-Patent Document 3).
Fertilizers containing silicic acid are not known in hydroponics (see, for example, Non-Patent Document 4).

○ Prior literature
JP-A-5-095739 (Claims) JP-A-7-203787 (Claims) JP-A-9-313055 (Claims) Japanese Patent Laid-Open No. 3-124810 (Claims) JP 2000-191339 A (Claims) JP 2000-281380 A (Claims) Japanese Patent Laid-Open No. 2001-026438 (Claims) Japanese Patent Application Laid-Open No. 07-206566 (Claims and Examples) Seiichi Kusakari, 5 others, “Control effect of Pythium root rot in nutrient solution cultivation with silver zeolite”, 29th Annual Meeting of the Japan Society for Antimicrobial Prevention, May 30, 2002, B-25 “Suppression of strawberry powdery mildew by applying potassium silicate aqueous solution”, Hyogo Agricultural Technology, No. 110, July 2000 “Effective Potassium Silicate and its Effect on Strawberry Powdery Mildew Suppression”, Hyogo Agricultural Technology, No. 116, July 2001 Otsuka Chemical Co., Ltd. website, Otsuka House Fertilizer Series <URL: http://www.tok.otsukac.co.jp/otsukac/agro/catalog_hiryo/index_h.html>

  The present invention is to establish a nutrient solution sterilization method that is easy to manage at low cost and has a high sterilization effect, and to provide a sterilization apparatus and a nutrient solution cultivation method in the nutrient solution cultivation of plants using the method, It is intended to provide a method for continuously supplying silicate ions capable of sterilizing a nutrient solution and imparting resistance to diseases such as powdery mildew to plants.

As a result of intensive studies, the inventor has found that the mass ratio in terms of oxide is 15 to 60% SiO ₂ , 10 to 40% K ₂ O and 0.1 to 5% Ag ₂ O, P ₂ O It has been found that the above-mentioned problems can be solved by a nourishing liquid fungicide in nourishing liquid culture consisting of soluble glass containing ₅ to 10% and / or ₅ to 50% of B ₂ O ₃ . Further, the soluble glass has MgO of 15% or less, CaO of 35% or less, MnO ₂ of 2% or less, Fe ₂ O ₃ of 3% or less, CuO of 1% or less, ZnO of 1% or less, and / or MoO ₃ is a nutrient solution disinfectant in nutrient solution cultivation containing 1% or less. Moreover, this nutrient solution disinfectant is used as a fertilizer.
It is a nutrient solution cultivation apparatus using a nutrient solution disinfectant, and is a nutrient solution cultivation method using this.

  Hereinafter, the present invention will be described in detail.

○ Dissolvable glass The soluble glass used in the nutrient solution bactericide of the present invention is capable of eluting a metal having antibacterial properties into the nutrient solution, and examples of the metal having antibacterial properties include silver.

The soluble glass may be any glass that can elute silver ions and silicate ions into the nutrient solution, and the type of glass is not limited.
Examples of the glass that has water solubility and can be used for the soluble glass that easily adjusts the dissolution rate of the antibacterial metal ions include phosphosilicate glass and borosilicate glass. Examples of the glass that is soluble and can be used for the soluble glass that easily adjusts the dissolution rate of silicate ions include phosphosilicate glass and borosilicate glass. The dissolution rate of antibacterial metal ions and antibacterial metal ions and silicate ions from the soluble glass is determined by the content of antibacterial metals, the content of silica, the content and composition of glass forming components, and the content of glass modifying components. The amount and composition can be adjusted by the content and composition of other components. Since the nutrient solution fungicide of the present invention is always in contact with a nutrient solution for plant cultivation, it is adjusted to different elution conditions for antibacterial metal ions or antibacterial metal ions and silicate ions than those for horticultural cultivation such as pots. doing.

The soluble glass, for example, a SiO ₂ 15 to 60 wt%, the B ₂ O ₃ 5 to 50 wt%, the K ₂ O 10 to 40 wt%, the MgO 0 to 15 mass%, the CaO 0 to 35 % By mass, 0-2% by mass of MnO ₂ , 0-3% by mass of Fe ₂ O ₃ , 0-1% by mass of CuO, 0-1% by mass of ZnO, 0-1% by mass of MoO ₃ , Ag ₂ O from 0.1 to 5 mass% content for soluble glass, a SiO ₂ 15 to 60 wt%, P ₂ O ₅ 10 to 50 wt%, 10 to 40 wt% of K ₂ O, the MgO 0 to 15 0 to 35% by mass, CaO 0 to 35% by mass, MnO ₂ 0 to 2% by mass, Fe ₂ O ₃ 0 to 3% by mass, CuO 0 to 1% by mass, ZnO 0 to 1% by mass, MoO ₃ 0 to 1 mass%, soluble glass containing Ag ₂ O 0.1 to 5% by weight, the SiO ₂ 15 to 60 wt%, the B ₂ O ₃ 5 to 50 wt%, P _{2 5} 10 to 50 wt%, the K ₂ O 10 to 40 wt%, MgO 0 to 15 wt%, 0 to 35 wt% of CaO, the MnO ₂ 0 to 2 wt%, 0 to Fe ₂ O ₃ 3% by mass, 0 to 1% by mass of CuO, 0 to 1% by mass of ZnO, 0 to 1% by mass of MoO ₃ , 15 to 5% by mass of Ag ₂ O, 15 of SiO ₂ 50 mass%, P ₂ O ₅ 25 to 50 wt%, the K ₂ O 10 to 40 wt%, the MgO 0 to 15 wt%, 0 to 35 wt% of CaO, the MnO ₂ 0 to 2 wt% the Fe ₂ O ₃ 0 to 3 wt%, CuO and 0-1% by weight, ZnO 0 to 1 wt%, the MoO ₃ 0 to 1 mass%, containing Ag ₂ O 0.1 to 5 wt% Examples include soluble glass.

More preferably, the SiO ₂ 15 to 60 wt%, the B ₂ O ₃ 5 to 50 wt%, the K ₂ O 10 to 40 wt%, the MgO 0 to 15 wt%, 0 to 35 wt% of CaO, MnO ₂ is 0 to 2% by mass, Fe ₂ O ₃ is 0 to 3% by mass, CuO is 0 to 1% by mass, ZnO is 0 to 1% by mass, MoO ₃ is 0 to 1% by mass, and Ag ₂ O is 0%. .1-5 mass% soluble glass, SiO ₂ 15-60 mass%, P ₂ O ₅ 10-50 mass%, K ₂ O 10-40 mass%, MgO 0-15 mass%, CaO 0 to 35 wt%, the MnO ₂ 0 to 2 wt%, the Fe ₂ O ₃ 0 to 3 wt%, the CuO 0 to 1 mass%, the ZnO 0 to 1 wt%, the MoO ₃ 0 to 1 It is a soluble glass containing 0.1% to 5% by mass of Ag ₂ O.

  The soluble glass used in the present invention is a compound containing necessary components such as oxides, hydroxides, borates, phosphates, chlorides, nitrates, sulfates, carbonates, etc. in a predetermined mixing amount. After being mixed well, it can be obtained by heating and melting, rapid cooling, crushing, and classification.

The elution rate of silver ions and silicate ions from the soluble glass can be achieved by adjusting the dissolution rate of the glass. That is, since the dissolution rate can be increased by increasing the content of boric acid (B ₂ O ₃ ), phosphoric acid (P ₂ O ₅ ), alkali metal ions, or alkaline earth metal ions in the glass composition, The elution rate of silver ions and silicate ions into the nutrient solution can be controlled.

The said soluble glass can obtain the optimal particle diameter for hydroponics by classifying. Moreover, it can be set as the spherical shape of arbitrary particle sizes at the time of glass manufacture. The spherical glass (glass beads) can be obtained by a usual method. For example, there are a method in which molten glass is dropped as droplets and solidified into a spherical shape, and a method in which a glass raw material slurry is sprayed into a flame to melt and solidify.
Furthermore, powdery glass can be formed into a granular shape.
There are no particular limitations on the method of making the granular antibacterial agent, and examples thereof include a method of supporting the surface on a surface of a granular ceramic and the like, a method of forming a granular product using a binder, and the like.

  Here, the granular ceramic refers to a natural or artificially produced inorganic solid material and granular glass. In other words, it refers to ceramics, ceramic products, glass, sand, pebbles, etc., which are generally said to the public. Examples include silica, alumina, zirconia, mullite, glass beads, or balls. The shape is not particularly limited, such as a spherical shape, a cylindrical shape, a disk shape, a cubic shape, a rectangular parallelepiped shape, or an indefinite shape.

  As a method for supporting the fine powder of soluble glass on the surface of the granular ceramic or the like, the raw material powder or raw material slurry of the soluble glass can be adhered to the surface of the granular ceramic and heated.

  In addition, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyacrylic acid ester, epoxy resin, polyethylene, polypropylene, ABS resin, polyester, etc. are used as a binder, If it is a plastic resin, it is supported on the surface of the granular ceramic by heating it above the softening point, if it is a thermosetting resin, it is heated above the curing temperature, and if it is a UV curable resin, it is cured by UV irradiation. You can do it.

  As another granulation method, there is a method of granulating using a molding binder without using a carrier. For example, there is a method using silica gel. Silica gel is a very porous material, although its physical strength is lower than that supported on granular ceramics, etc., so it has the advantages of high contact efficiency between soluble powder of fine powder and nutrient solution and high bactericidal effect. is there.

  There is no limitation in particular about the silica gel to be used. Any of A type, B type, ID type, etc., which are generally referred to, may be used. As a method for supporting silica gel, any method of supporting an inorganic compound on silica gel can be applied. For example, after adding a fine powder of soluble glass to an aqueous sodium silicate solution, sulfuric acid or hydrochloric acid is added to prepare a colloidal silicate solution, which is dropped into water to obtain a granular product. The obtained granular product is a so-called hydrogel containing a large amount of water. Although this can be used as it is, in order to improve water resistance, it is preferable to dry it at about 100 to 300 ° C. A granular product can be obtained by adding a fine powder of soluble glass to sulfuric acid or hydrochloric acid instead of a sodium silicate aqueous solution, and then adding the sodium silicate aqueous solution. Further, a fine powder of soluble glass may be added immediately after the silicate colloid solution is formed.

  In addition, as a binder, use is made of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyacrylic ester, epoxy resin, polyethylene, polypropylene, ABS resin, polyester, etc. After extruding, it is possible to cut and granulate by granulation.

There is no particular limitation on the size of the soluble glass used for hydroponics, but a granular product is preferable to a powder when used in a column or a filtration tower.
The particle size of the soluble glass used by being packed in a column or a filtration tower is preferably about 0.05 mm or more, more preferably 1 mm or more. On the other hand, if the particle size is too large, the surface area becomes small. Therefore, the particle size is substantially preferably about 20 mm or less, more preferably 15 mm or less. That is, the size of the granular antibacterial agent is preferably 0.05 to 20 mm, more preferably 0.1 to 15 mm, and particularly preferably 1 to 15 mm. The fine powder soluble glass means a glass having a particle size of less than 0.05 mm, but depending on how it is used, the fine powder soluble glass can be used as it is.

O Hydroponic cultivation method In FIG. 1, the structure of the general circulation type hydroponic cultivation apparatus was shown. In the mixing tank 5, the returning nutrient solution from the drainage tank 4 and the nutrient solution stock solution from the nutrient solution stock tank 3 are mixed, and the nutrient solution is sent to the cultivation bed 1. In FIG. 1, only two cultivation beds are displayed. However, in an actual apparatus or cultivation method, cultivation beds can be further installed according to the cultivation scale. The soluble glass of the present invention can be incorporated into such an exemplified hydroponic cultivation apparatus. For example, a method of filling a mesh bag or mesh bag with soluble glass and installing it in a drainage tank or a mixing tank, filling a filtration tower or column with soluble glass, and piping between the cultivation bed and the drainage tank In addition, there is a method of incorporating in a pipe between the drainage tank and the mixing tank, or a pipe between the mixing tank and the cultivation bed.
In addition, a part of the nutrient solution is withdrawn from one of the pipes or tanks of the nutrient solution cultivation apparatus by bypass, and is treated by flowing it into a cartridge, packed tower or column filled with soluble glass, and then returned to the system again. The method may be used. Further, there is a method in which a filtration device such as sand filtration is provided in the system, and a soluble glass is mixed in the filter medium, or a layer of the soluble glass is incorporated in front of or behind the sand filter.
The soluble glass of the present invention can be incorporated into a nutrient solution cultivating apparatus as at least one place as a nutrient solution fungicide, and is preferably incorporated into the nutrient solution cultivating apparatus in at least two places. In addition, this hydroponic cultivation may be a pouring type or a circulation type, and is preferably a circulation type.
In the present invention, a sterilizer using ozone or ultraviolet rays may be used in combination.

The elution concentration of the antibacterial metal and silicate ions in the nutrient solution varies depending on the conditions of the nutrient solution cultivation, but may be adjusted to 20 ppb or more if it is approximately silver ions. Further, the silicate ion concentration may be adjusted to 1 ppm or more, preferably 10 ppm or more in the nutrient solution. However, those having excessively high concentrations are not preferable because the frequency of replacement of the soluble glass during running increases and the cost and maintenance deteriorate. In addition, the plant may be damaged.
Phosphorus eluted from the soluble glass can also be used as a fertilizer.
The time for replacement of the soluble glass in the nutrient solution cultivation apparatus may be determined by monitoring the antibacterial metal ions in the nutrient solution, may be determined from the volume of the soluble glass, and the replacement time is determined. You may go.

  The nutrient solution bactericidal agent can be used for both the flow-through cultivation and the circulation type nutrient solution cultivation, and is preferably used for the circulation type nutrient solution cultivation in which pathogenic bacteria need to be strictly controlled. These nutrient solution fungicides can be used for cultivation using soil, depending on the conditions of use. In addition, since these nutrient solution disinfectants are easy to control, for example, various ions to be eluted, it is preferable to use them in nutrient solution cultivation rather than soil cultivation.

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples. In addition, a part shows a mass part.

<Production Example 1>
A composition prepared by thoroughly mixing the composition (each part by mass) shown in Table 1 was melted at 1000 to 1400 ° C. to produce glass, and the obtained glass was crushed and classified to obtain a particle size of about 1 mm to 5 mm. (1) to (6) were obtained.

The dissolution of silver ions into the nutrient solution in the soluble glass (sample C) prepared in Production Example 1 and silver zeolite was examined. That is,
1) 150 g of Otsuka House Fertilizer No. 1 (manufactured by Otsuka Chemical Co., Ltd.) is dissolved in 1,000 mL of tap water (100-fold stock solution).
2) 100 g of Otsuka House Fertilizer No. 2 (Otsuka Chemical Co., Ltd.) is dissolved in 1,000 mL of tap water (100-fold stock solution).
3) Otsuka House Fertilizer No. 1 and No. 2 100-fold stock solutions were mixed with 30 mL each and 2,940 mL of tap water to make a test nutrient solution (Otsuka House Fertilizer Series A prescription).
4) In a test nutrient solution of 3,000 mL at room temperature, 3 g of sample C or 3 g of silver zeolite was placed in a mesh bag and dipped in a suspended thread.
5) Slowly stirred at room temperature for 21 days.
Then, sampling was performed every predetermined time, and the silver ion concentration was measured using an ICP emission spectrometer.
6) After 7 days, replace the test solution with a new one and perform the same test.
7) After another 7 days, do the same.
The silver ion concentration (mg / L) in each sample thus obtained is shown in Table 3.

As can be seen from Table 3, the elution of silver ions from the silver zeolite into the nutrient solution starts faster than the soluble glass, but it cannot be eluted for a long period of time. Compared to this, elution of silver ions from the soluble glass into the nutrient solution can continue to elute silver ions at a required concentration for a long period of time, although the rise is smaller than that of silver zeolite.
Therefore, the soluble glass can be used for a long period of time by being incorporated in a hydroponic apparatus, and maintenance of the apparatus and chemicals can be reduced.

<Examples 2 to 6>
Two 10L nutrient solution stock tanks, one 50L mixing tank, one 50L drainage tank, two 20cm wide, 20cm deep, 200cm long cultivation beds (bed is rock wool), and a circulation pump The provided hydroponic device was prepared. This conceptual diagram is shown in FIG. Ten tomato plants were transplanted to the cultivation bed, and 20 L of nutrient solution (Otsuka House Fertilizer Series A formulation) was circulated intermittently. The drainage was returned to the mixing tank once a day. The reduced nutrient solution was newly prepared and added once a day.
The nutrient solution was inoculated with Pythium aphanidermatum. As shown in Table 4, soluble glass (samples i to e) was incorporated into the hydroponic cultivation apparatus.
The test was started and the situation of the tomatoes was observed 8 weeks later.

<Examples 7 to 8>
Two 10L nutrient solution stock tanks, one 50L mixing tank, one 50L drainage tank, two 20cm wide, 20cm deep, 200cm long cultivation beds (bed is rock wool), and a circulation pump The provided hydroponic device was prepared. This conceptual diagram is shown in FIG. Ten tomato plants were transplanted to the cultivation bed, and 20 L of nutrient solution (Otsuka House Fertilizer Series A formulation) was circulated intermittently. The drainage was returned to the mixing tank once a day. The reduced nutrient solution was newly prepared and added once a day. As shown in Table 5, soluble glass (samples A and C) was incorporated into the hydroponic cultivation apparatus. The test was started and the situation of the tomatoes was observed 8 weeks later.

  By using the soluble glass, it is possible to prevent disease infection in the circulating hydroponic cultivation of cultivated plants. In addition, it becomes difficult to be infected with diseases such as powdery mildew. It was easy to incorporate the method of the present invention into the circulation type hydroponic culture because no difference was observed in the preventive effect of disease infection regardless of when the soluble glass was brought into contact with the nutrient solution. That is, it is clear that it can be carried out in any place in consideration of the installation location and maintenance of the circulation type hydroponic cultivation, and can be easily incorporated into an existing circulation type hydroponic cultivation apparatus.

  By using the nutrient solution fungicide of the present invention for circulation type nutrient solution culture, it is possible to prevent disease infection of cultivated plants caused by pathogenic bacteria mixed in the nutrient solution circulating in the nutrient solution culture apparatus. In addition, it becomes difficult to be infected with diseases such as powdery mildew. From this, it is possible to continue the hydroponics for a long time. Moreover, the cultivation method of this invention can also reduce the load to an environment.

Figure of typical circulation type hydroponic cultivation equipment

Explanation of symbols

1 Cultivation Bed 2 Pump 3 Nutrient Solution Stock Tank 4 Drainage Tank 5 Mixing Tank 6 Water Supply 7 Drainage ← Direction of Nutrient Solution Flow

Claims (3)

At a weight ratio of oxide equivalent, SiO ₂ 15 to 60% and K ₂ O is 10-40% and Ag ₂ O is 0.1 to 5% P ₂ O ₅ from 10 to 50% and / or B A nutrient solution bactericidal agent in nutrient solution culture composed of soluble glass containing 5 to 50% ₂ O ₃ . The soluble glass of claim 1, wherein MgO is 15% or less, CaO is 35% or less, MnO ₂ is 2% or less, Fe ₂ O ₃ is 3% or less, CuO is 1% or less, ZnO is 1% or less, and A nutrient solution bactericidal agent in nutrient solution cultivation containing MoO ₃ of 1% or less.   A nutrient solution cultivation apparatus using the nutrient solution disinfectant according to claim 1 or 2.

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