JPWO2017110385A1 - Artificial soil medium - Google Patents

Abstract

Provided is an artificial soil medium having improved fertilizer retention and capable of efficiently supplying nitrate nitrogen to cultivated plants. An artificial soil medium 100 that can convert ammonia nitrogen into nitrate nitrogen, and includes at least a cation exchanger 1 capable of supporting ammonium ions and a nitrifying bacterium 4 that oxidizes ammonium ions into nitrate ions. The artificial soil culture medium 100 contains artificial soil particles 50 a (50) containing the cation exchanger 1 and artificial soil particles 50 b (50) containing nitrifying bacteria 4. The artificial soil particle 50 (50a, 50b) is a porous structure having a bulk specific gravity of 0.1 to 0.7 g / cc, and a void peak diameter of 50 nm to 100 μm. The nitrifying bacteria 4 contain at least ammonia oxidizing bacteria and nitrite oxidizing bacteria.

Description

  The present invention relates to an artificial soil medium used for cultivation of root vegetables, flower buds, foliage plants and the like.

  Artificial soil has been used for indoor greening and vegetable cultivation in plant factories, but in recent years, the need for artificial soil has diversified. For example, artificial soil is used to produce various types of ornamental plants and flower buds. Plants are being cultivated.

  In the development of artificial soil, a function capable of appropriately maintaining and managing fertilizer is required while achieving the same plant growth ability as natural soil. In particular, it is necessary for an artificial soil medium to absorb and retain an appropriate amount of fertilizer in order to realize an optimum cultivation schedule according to the type of plant.

  It is known that three elements of nitrogen, phosphorus, and potassium are necessary for plant growth. Among them, nitrogen is an important element for constituting a plant body. Plants take in most of the nitrogen components (nitrogen nutrients) as nutrients in the form of nitrate nitrogen (hereinafter also referred to as nitric acid or nitrate ions). In general, nitrogen nutrients contained in organic fertilizers and the like exist as ammonia nitrogen (hereinafter also referred to as ammonia or ammonium ions), but ammonia nitrogen is converted to nitrate nitrogen by nitrifying bacteria present in the soil. Converted (oxidized). Plants take in and use this oxidized nitrate nitrogen.

  In the plant factory, when using artificial soil instead of natural soil, it is necessary to give nitrate nitrogen instead of ammonia nitrogen as a nitrogen nutrient to be given to plants. This is because ammonia nitrogen is difficult to be absorbed by plants as a nitrogen nutrient. Even if ammonia nitrogen is included in the artificial soil, there is no nitrifying bacteria that are resident in the natural soil in the artificial soil, so the ammonia nitrogen cannot be oxidized to nitrate nitrogen.

  As an example of a conventional artificial soil culture medium, Patent Document 1 proposes artificial soil using a polyvinyl formal resin porous material. Since the artificial soil of Patent Document 1 is excellent in water retention and has a high ability to retain microorganisms, it can provide a new artificial soil excellent in plant growth without using chemical fertilizers.

JP 2014-143931 A

  The artificial soil of Patent Document 1 uses soil and organic materials in addition to the polyvinyl formal resin porous body to supply fertilizer to cultivated plants. Since soil and organic materials are natural, there are variations in the number and type of bacteria contained, the fertilizer content, and the like. For this reason, since water retention and fertilizer retention change with the quantity and kind of soil and organic material which are contained in artificial soil, high fertilizer retention is not necessarily obtained. Thus, the conventional artificial soil culture medium has room for improvement in terms of fertilizer retention.

  This invention is made | formed in view of the said problem, and it aims at providing the artificial soil culture medium which can supply fertilizer to a cultivated plant efficiently, and fertilizer retention is improved.

The characteristic configuration of the artificial soil culture medium according to the present invention for solving the above problems is as follows.
An artificial soil medium capable of converting ammonia nitrogen into nitrate nitrogen,
The object is to contain at least a cation exchanger capable of supporting ammonium ions and a nitrifying bacterium that oxidizes the ammonium ions into nitrate ions.

  According to the artificial soil culture medium of this configuration, the ammonium ion is retained in the artificial soil culture particle by the cation exchanger taking in ammonium ions (ammonia nitrogen), and the retained ammonium ions are nitrate ions by nitrifying bacteria. It is efficiently oxidized to (nitrate nitrogen). Nitrate ions generated by this process are released from artificial soil particles and become nutrients for cultivated plants. Thus, the artificial soil medium of the present invention can efficiently supply nitrate ions to cultivated plants while realizing excellent fertilizer retention, and as a result, can promote the growth of cultivated plants.

In the artificial soil medium according to the present invention,
It is preferable to contain artificial soil particles containing the cation exchanger and artificial soil particles containing the nitrifying bacteria.

  According to the artificial soil medium of this configuration, the artificial cation exchanger contained in the artificial soil particles includes ammonium sulfate, because the artificial soil particles include artificial soil particles containing a cation exchanger and artificial soil particles containing nitrifying bacteria. When ions are taken in, the ammonium ions are oxidized to nitrate ions by nitrifying bacteria contained in another artificial soil particle. At this time, since the nitrate ion is an anion, the nitrate ion is positively released from the artificial soil particles containing the cation exchanger. On the other hand, when root acid is discharged from the roots of the cultivated plant, hydrogen ions derived from the root acid are exchanged with ammonium ions incorporated in the cation exchanger in the artificial soil particles. As a result, ammonium ions are released from the artificial soil particles, and then oxidized to nitrite ions by nitrifying bacteria contained in other artificial soil particles. As a result of the production of nitrate ions in this process, nitrate nitrogen is supplied to the cultivated plant.

In the artificial soil medium according to the present invention,
The artificial soil particles are preferably a porous structure having a bulk specific gravity of 0.1 to 0.7 g / cc, and a void peak diameter of 50 nm to 100 μm.

  According to the artificial soil medium of this configuration, the artificial soil particle is a porous structure having a bulk specific gravity of 0.1 to 0.7 g / cc and a void peak diameter of 50 nm to 100 μm. In this gap, nitrifying bacteria can easily propagate, and movement of the nitrifying bacteria can be facilitated.

In the artificial soil medium according to the present invention,
The nitrifying bacteria preferably contain at least ammonia oxidizing bacteria and nitrite oxidizing bacteria.

  According to the artificial soil medium of this configuration, since the nitrifying bacteria contain ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, the ammonia-oxidizing bacteria oxidize ammonium ions incorporated into the cation exchanger into nitrite ions. And nitrite oxidizing bacteria can oxidize nitrite ions to nitrate ions.

In the artificial soil medium according to the present invention,
The ammonia oxidizing bacterium is at least one selected from the group consisting of the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosorobas, Brevibacillus, and Xanthomonas,
The nitrite-oxidizing bacterium is preferably at least one selected from the group consisting of the genus Nitrobacter, Nitrococcus, and Nitrospira.

  According to the artificial soil culture medium of this configuration, ammonium ions incorporated into the cation exchanger can be more reliably oxidized to nitrate ions by combining the above appropriate bacteria as ammonia oxidizing bacteria and nitrite oxidizing bacteria. .

In the artificial soil medium according to the present invention,
The ratio of the number of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria is preferably 1: 1000 to 10: 1.

  According to the artificial soil culture medium of this configuration, since the ratio of the number of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria is set in the above range, each nitrifying bacterium is ammonium that has been incorporated into the cation exchanger. Ions can be more efficiently oxidized to nitrate ions.

In the artificial soil medium according to the present invention,
The nitrifying bacteria are preferably heterotrophic bacteria that directly oxidize ammonium ions to nitrate ions.

  According to the artificial soil culture medium of this configuration, since a bacterium that oxidizes ammonium ion to nitrate ion in one step is used, ammonium ion taken into the cation exchanger by containing at least one kind of bacterium is converted into nitrate ion. Can be oxidized. For this reason, the kind of microbe used as a raw material of artificial soil particles can be reduced.

In the artificial soil medium according to the present invention,
The heterotrophic bacterium is preferably at least one selected from the group consisting of Arthrobacter, Bacillus, Ocrobacterium, Delftita, and Stentomonas.

  According to the artificial soil culture medium of this structure, the ammonium ion taken in the cation exchanger can be more reliably oxidized to nitrate ion by selecting said appropriate bacteria as heterotrophic bacteria.

In the artificial soil medium according to the present invention,
The content of the nitrifying bacteria is preferably 10 ⁵ to 10 ⁹ CFU / g.

  According to the artificial soil culture medium of this structure, since the content of nitrifying bacteria is set in the above range, ammonium ions taken into the cation exchanger can be more reliably oxidized to nitrate ions.

In the artificial soil medium according to the present invention,
The maximum water retention amount is 30 cc / 100 cc or more, and the gas phase ratio when the water retention amount is 30 cc / 100 cc is preferably 20 to 60%.

  According to the artificial soil culture medium of this configuration, since the gas phase rate of the artificial soil culture medium is set in the above range, the activity of nitrifying bacteria, which are aerobic bacteria, becomes active, and ammonium ions in the artificial soil culture medium Can be rapidly and fully oxidized to nitrate ions.

In the artificial soil medium according to the present invention,
It is preferably used in an environment where the temperature is 10 to 40 ° C. and the pH is 4.0 to 7.5.

  According to the artificial soil culture medium of this structure, since the artificial soil culture medium is used in the above environment, the activity of nitrifying bacteria is sufficiently activated. Therefore, nitrifying bacteria can oxidize ammonium ions to nitrate ions quickly and sufficiently in the artificial soil medium.

FIG. 1 is a schematic diagram of an artificial soil culture medium according to the present invention. FIG. 2 is a schematic diagram of first artificial soil particles contained in the artificial soil medium. FIG. 3 is a schematic diagram of second artificial soil particles contained in the artificial soil medium. FIG. 4 is an explanatory diagram of the production of nitrate ions in the artificial soil culture medium. FIG. 5 is an explanatory diagram of the generation of nitrate ions in the artificial soil culture medium.

  Hereinafter, an embodiment relating to an artificial soil culture medium according to the present invention will be described with reference to the drawings. The present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Artificial soil medium>
FIG. 1 is an explanatory view conceptually showing an artificial soil culture medium according to the present invention. FIG. 1A is a schematic diagram of an artificial soil culture medium 100 composed of a plurality of artificial soil particles 50. FIG.1 (b) is an enlarged view of area | region A1 enclosed with the broken-line circle | round | yen in the artificial soil particle 50 of Fig.1 (a). As shown in FIG. 1A, the artificial soil culture medium 100 is composed of a plurality of artificial soil particles 50, and has a certain gap S between adjacent artificial soil particles 50. Since air and water can mainly pass through the gap S, the plant 30 cultivated in the artificial soil culture medium 100 can take in oxygen and moisture necessary for growth using the gap S. .

  As shown in FIG.1 (b), the artificial soil particle 50 contains the 1st artificial soil particle 50a and the 2nd artificial soil particle 50b. However, the artificial soil culture medium 100 may include particles other than the first artificial soil particles 50a and the second artificial soil particles 50b. The 1st artificial soil particle 50a contains the cation exchanger 1 inside. The cation exchanger 1 can hold ammonium ions in the first artificial soil particles 50a by taking in ammonium ions (ammonia nitrogen). The second artificial soil particle 50 b contains nitrifying bacteria 4. Ammonium ions are oxidized to nitrate ions (nitrate nitrogen) by nitrifying bacteria 4. That is, in the artificial soil medium 100, ammonium ions are retained in the artificial soil medium 100, and the retained ammonium ions are efficiently oxidized to nitrate ions by the nitrifying bacteria 4. Nitrate ions generated by this process are released from the artificial soil medium 100 and supplied to the cultivated plant 30 as nitrate nitrogen (nutrient). As described above, the artificial soil culture medium 100 can efficiently supply nitrate ions to the cultivated plant 30 while realizing excellent fertilizer retention. As a result, the cultivated plant 30 can be promoted to grow. In addition, the ammonium ion may be previously taken in in the 1st artificial soil particle 50a, and the effort which supplies the liquid fertilizer containing ammonia later in this case can be saved.

  The artificial soil culture medium 100 has a maximum water retention amount of 30 cc / 100 cc or more and a water retention amount of 30 cc / 100 cc so that oxygen can be taken into the gaps S between the artificial soil particles 50. The gas phase rate of 100 is set to 20 to 60%, preferably 30 to 60%. The amount of water retained is expressed as the amount of water (cc) that the 100 cc artificial soil medium 100 can hold. Since the artificial soil culture medium 100 of the present invention has a predetermined gas phase rate while having high water retention, the activity of the nitrifying bacteria 4 that are aerobic bacteria becomes active. Inside, ammonium ions can be sufficiently oxidized to nitrate ions. When the gas phase rate of the artificial soil culture medium 100 is less than 20%, the activity of the nitrifying bacteria 4 is insufficient, so that oxidation of ammonium ions hardly occurs. When the gas phase rate exceeds 60%, the gap between the artificial soil culture medium 100 becomes large, and the strength of the artificial soil culture medium 100 itself becomes weak. Further, the oxidation from ammonium ions to nitrate ions by nitrifying bacteria 4 is not greatly improved.

  Since the nitrifying bacteria 4 can sufficiently act, the environment in which the artificial soil medium 100 is used has a temperature of 10 to 40 ° C., preferably 15 to 30 ° C., and a pH of 4.0 to 7.5, preferably Set to 5.0-7.0. Under such an appropriate environment, the activity of the nitrifying bacteria 4 is sufficiently activated, and ammonium ions can be sufficiently oxidized to nitrate ions in the artificial soil medium 100. When the temperature of the artificial soil medium 100 is less than 10 ° C., the nitrifying bacteria 4 may stop its activity, and when the temperature exceeds 40 ° C., the nitrifying bacteria 4 may be killed. If the pH is less than 4.0 or exceeds 7.5, nitrifying bacteria 4 may be killed.

<Artificial soil particles>
Hereinafter, the first artificial soil particles 50a and the second artificial soil particles 50b will be described with reference to FIGS.

(First artificial soil particles)
FIG. 2 is a schematic diagram of the first artificial soil particles 50a contained in the artificial soil culture medium according to the present invention. As shown in FIG. 2, the first artificial soil particle 50 a contains a cation exchanger 1. The first artificial soil particles 50a are formed as a granular material in which a plurality of cation exchangers 1 are assembled. The cation exchanger 1 is formed as a granular material bound by a binder or the like. In FIG. 2, the binder and the like are not shown, but the contact portion between the cation exchangers 1 is solidified by the binder or the like. As shown in FIG. 2, there are voids 2 between the cation exchangers 1. The gap 2 can hold moisture, nutrients, and the like. The void 2 forms a communication hole in which the voids 2 are continuously communicated from the void 2 to the outside (outside of the particles). On the other hand, the cation exchanger 1 has pores 3 from the surface to the inside. Since the pore 3 communicates with the gap 2, the pore 3 communicates with the outside (outside the particle) through the communication hole. For this reason, moisture, nutrients, etc. can flow between the outside (outside the particles) and the pores 3. For example, when ammonium ions are supplied to the first artificial soil particles 50a later, the ammonium ions enter the first artificial soil particles 50a through the communication holes. Since ammonium ions are cations, they are taken into the cation exchanger 1 existing inside the first artificial soil particles 50a. In this way, ammonium ions are included in the first artificial soil particles 50a.

The cation exchanger 1 contained in the first artificial soil particle 50a is provided with a material having a cation exchange ability or a cation exchange ability so that sufficient ammonium ions can be held inside the first artificial soil particle 50a. Material is used. As a material having a cation exchange capacity, a cation exchange mineral or a cation exchange resin can be used. Examples of cation exchange minerals include smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, and zeolite. Examples of the cation exchange resin include a weak acid cation exchange resin and a strong acid cation exchange resin. Among these, zeolite which is a cation exchange mineral or bentonite is preferable. The cation exchange mineral and the cation exchange resin can be used in combination of two or more. It is also effective to use diatomaceous earth mixed with a cation exchange mineral and a cation exchange resin. For example, if a mixture of diatomaceous earth and zeolite at an appropriate blending ratio is used, the first artificial soil particles 50a having both water retention and fertilizer retention can be designed while being relatively inexpensive. . Separately, prepare a porous material that does not have ion exchange capacity (for example, polymer foam, glass foam, etc.), and press-fit the material with the above ion exchange capacity into the pores of the porous material. It is also possible to introduce it by impregnation or the like and use it. Examples of the material imparted with the cation exchange ability include cation exchange minerals, humus, and cation exchange resins. The material provided with the cation exchange capacity can take in and hold fertilizers such as NH ₄ ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , or hydrogen ions of root acid.

  The cation exchange capacity of the cation exchange mineral and the cation exchange resin is set to 10 to 700 meq / 100 g, preferably 20 to 700 meq / 100 g, and more preferably 30 to 700 meq / 100 g. When the cation exchange capacity is less than 10 meq / 100 g, the nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the cation exchange capacity exceeds 700 meq / 100 g, the effect is not greatly improved and it is not economical.

(Second artificial soil particle)
FIG. 3 is a schematic diagram of the second artificial soil particles 50b contained in the artificial soil culture medium according to the present invention. Fig.3 (a) is a schematic diagram of the 2nd artificial soil particle 50b. FIG. 3B is an enlarged view of a region A2 surrounded by a broken-line circle in the second artificial soil particle 50b of FIG. As shown in FIG. 3A, the second artificial soil particle 50 b contains a plurality of nitrifying bacteria 4. As shown in FIG. 3 (b), the second artificial soil particle 50b is a porous structure including the inorganic filler 5, and is formed as a granular material in which the inorganic filler 5 and fibers are bound by a binder or the like. Although the inorganic filler 5 will not be specifically limited if it is an inorganic substance, It is preferable that it is inorganic porous bodies, such as a porous mineral, an inorganic foam, an inorganic porous aggregate. Examples of the porous mineral include diatomaceous earth, perlite, vermiculite, and pumice. Examples of the inorganic foam include glass foam, shale foam, and shirasu balloon. Examples of the inorganic porous aggregate include foamed concrete and foamed brick. Among these inorganic porous bodies, diatomaceous earth and pearlite, which are porous minerals, are excellent in water retention, have a good appearance because they have a white appearance, have good colorability, and are inexpensive. Since it is also inexpensive, it is particularly preferably used as a material for artificial soil used in large quantities. When it is desired to improve the fertilizer of the second artificial soil particle 50 b, a mineral having ion exchange ability can be used as the inorganic filler 5. Examples of the inorganic filler 5 include cation exchange minerals (for example, smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, and zeolite), anion exchange minerals ( For example, natural layered double hydroxides with double hydroxide as main skeleton such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, synthetic hydrotalcite and hydrotalcite-like substances, allophane, imogolite, kaolin And clay minerals). Each inorganic filler 5 listed above may be a mixture of two or more. For example, if diatomaceous earth and zeolite are selected as the inorganic filler 5 and are mixed at an appropriate blending ratio, the second artificial artificial fiber that has both water retention and fertilizer retention while being relatively inexpensive. Soil particles 50b can be designed. In FIG. 3, the binder and the like are not shown, but the contact portion of the inorganic filler 5 is solidified by the binder or the like. Gaps 6 are formed between the inorganic fillers 5.

  The nitrifying bacteria 4 contained in the second artificial soil particles 50b contain at least ammonia oxidizing bacteria and nitrite oxidizing bacteria so that ammonium ions taken into the second artificial soil particles 50b can be oxidized to nitrate ions. To do. Ammonia oxidizing bacteria can oxidize ammonium ions incorporated into the cation exchanger 1 to nitrite ions, and nitrite oxidizing bacteria can oxidize nitrite ions to nitrate ions. By combining the above appropriate bacteria, the ammonium ions taken into the cation exchanger 1 can be more reliably oxidized to nitrate ions.

  Examples of the ammonia-oxidizing bacteria used as nitrifying bacteria 4 include the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobas, Brevibacillus, and Xanthomonas. Examples of nitrite oxidizing bacteria used as nitrifying bacteria 4 include the genus Nitrobacter, the genus Nitrococcus, and the genus Nitrospira. Any of these may exist as autotrophic bacteria, and in particular, the genus Nitrosomonas, Nitrospira, and Nitrobacter that can be active even in an environment free from organic matter are preferable. Ammonia oxidizing bacteria and nitrite oxidizing bacteria can be used in combination of two or more. By combining appropriate bacteria as ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, the ammonium ions incorporated into the cation exchanger 1 can be more reliably oxidized to nitrate ions.

  The nitrifying bacteria 4 contained in the second artificial soil particles 50b are heterotrophic bacteria that directly oxidize ammonia to nitric acid so that ammonium ions taken into the second artificial soil particles 50b can be oxidized to nitrate ions. There may be. In this case, since ammonium ions can be oxidized to nitrate ions in one step, one type of bacteria can be used as a raw material for the second artificial soil particles 50b. Examples of the bacteria that oxidize ammonium ions to nitrate ions in one step include Arthrobacter, Bacillus, Ocrobacterium, Delftita, and Stentomohomonas. By selecting an appropriate bacterium as a heterotrophic bacterium, ammonium ions incorporated into the cation exchanger 1 can be more reliably oxidized to nitrate ions. The heterotrophic bacteria can also be used in addition to the ammonia-oxidizing bacteria and / or nitrite-oxidizing bacteria that can exist as the autotrophic bacteria described above.

  The second artificial soil particle 50b is composed of ammonia oxidizing bacteria used as the nitrifying bacteria 4 and nitrite oxidizing bacteria used as the nitrifying bacteria 4 so that ammonium ions taken inside are efficiently oxidized by nitrate ions. The ratio of the number of bacteria is set to 1: 1000 to 10: 1, preferably 1: 100 to 1: 1. Thereby, ammonium ions are more efficiently oxidized to nitrate ions by each nitrifying bacterium. If the ratio of the number of ammonia-oxidizing bacteria to nitrite-oxidizing bacteria is less than 1: 1000, there is a possibility that ammonium ions are not sufficiently oxidized to nitrite ions because there are few ammonia-oxidizing bacteria. On the other hand, if the ratio of the number of ammonia-oxidizing bacteria to nitrite-oxidizing bacteria exceeds 10: 1, nitrite ions may not be sufficiently oxidized to nitrate ions because there are few nitrite-oxidizing bacteria.

The content of nitrifying bacteria 4 contained in the second artificial soil particles 50b is set to 10 ⁵ to 10 ⁹ CFU / g, preferably 10 ⁷ to 10 ⁹ CFU / g. Thereby, ammonium ion is more reliably oxidized to nitrate ion. If the content of nitrifying bacteria 4 is less than 10 ⁵ CFU / g, ammonium ions may not be sufficiently oxidized to nitrate ions because nitrifying bacteria 4 are insufficient. On the other hand, even if the content of nitrifying bacteria 4 exceeds 10 ⁹ CFU / g, the effect is not greatly improved and it is not economical.

(Formation of artificial soil particles)
When an inorganic natural mineral such as zeolite is used as a material for the artificial soil particles 50 (50a, 50b), it can be granulated by utilizing a gelation reaction of a polymer gelling agent. Examples of the gelation reaction of the polymer gelling agent include gelation reaction between alginate and polyvalent metal ions, gelation reaction of carboxymethylcellulose (CMC), and gel formed by double helical structure reaction of polysaccharides such as carrageenan. Reaction. Among these, the gelation reaction between an alginate and a polyvalent metal ion will be described. Sodium alginate, which is one of alginates, is a neutral salt in which the carboxyl group of alginic acid is bonded to Na ions. Alginic acid is not required in water, but sodium alginate is water soluble. When an aqueous sodium alginate solution is added to an aqueous solution of polyvalent metal ions (for example, Ca ions), ionic crosslinking occurs between the molecules of sodium alginate and gelation occurs. In the case of this embodiment, the gelation reaction can be performed by the following steps. First, an alginate aqueous solution is prepared by dissolving alginate in water, cation exchanger 1 or inorganic filler 5 is added to the alginate aqueous solution, this is sufficiently stirred, and cation exchange is performed in the alginate aqueous solution. Let it be the liquid mixture which the body 1 or the inorganic filler 5 disperse | distributed. Next, the mixed solution is dropped into the polyvalent metal ion aqueous solution, and the alginate contained in the mixed solution is gelled in a granular form. Thereafter, the gelled particles are collected, washed with water, and sufficiently dried. Thereby, the granular material which the cation exchanger 1 or the inorganic filler 5 disperse | distributed in the alginic acid gel formed from an alginate and a polyvalent metal ion is obtained.

  The granular material is dried and classified as necessary, and becomes the first artificial soil particles 50b before the first artificial soil particles 50a or the nitrifying bacteria 4 are supported. The second artificial soil particles 50b before the nitrifying bacteria 4 are supported are dipped in a liquid containing the nitrifying bacteria 4 and further dried as necessary. Thereby, the 2nd artificial soil particle 50b with which nitrifying bacteria 4 were carried in the state where it entered into gap 6 between granular inorganic fillers 5 is obtained. The particle diameter of the artificial soil particles 50 (50a, 50b) is appropriately selected depending on the plant to be cultivated, but when targeting a houseplant or a flower bud, 1 to 10 mm is preferable, 2 to 8 mm is more preferable, and 2 to 2 5 mm is more preferable. When the particle size of the artificial soil particles 50 (50a, 50b) is less than 1 mm, the size of the gap formed between the artificial soil particles 50 (50a, 50b) is reduced, and moisture is excessively retained by the capillary force of the gap. Will be. As a result, it is difficult to absorb oxygen from the roots of the plant due to reduced drainage, and root rot may occur. On the other hand, if the particle size of the artificial soil particles 50 (50a, 50b) exceeds 10 mm, the size of the gap becomes large and the drainage property becomes excessive, so that the plant becomes difficult to absorb moisture or the artificial soil is sparse. There is a risk that the plant will fall over. The particle size of the artificial soil particles 50 (50a, 50b) can be adjusted by sieving.

  Examples of alginates that can be used in the gelation reaction include sodium alginate, potassium alginate, and ammonium alginate. These alginate can be used in combination of two or more. The concentration of the alginate aqueous solution is 0.1 to 5% by weight, preferably 0.2 to 5% by weight, and more preferably 0.2 to 3% by weight. When the concentration of the alginate aqueous solution is less than 0.1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 5% by weight, the viscosity of the alginate aqueous solution becomes too large, so that the cation exchanger 1 or the inorganic filler 5 It becomes difficult to stir the mixed solution to which is added and to add the mixed solution dropwise to the aqueous solution of polyvalent metal ions.

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

  In forming the artificial soil particles 50 (50a, 50b), granulation can be performed using a binder. For example, a binder or a solvent is added to and mixed with the cation exchanger 1 or the inorganic filler 5, and this raw material mixture is introduced into a granulator to produce rolling granulation, fluidized bed granulation, stirring granulation, compression granulation. Granules are formed by a known granulation method such as granulation, extrusion granulation, crush granulation, melt granulation, spray granulation or the like. Further, a binder is added to the cation exchanger 1 or the inorganic filler 5 and, if necessary, a solvent and the like are added and kneaded, and this is dried and made into a block shape. A mortar and pestle, hammer mill, roll crusher It is also possible to pulverize appropriately by a pulverizing means such as a granular material. The granular material is dried and classified as necessary to obtain artificial soil particles 50 (50a, 50b).

  As the binder constituting the artificial soil particle 50 (50a, 50b), either an organic binder or an inorganic binder can be used. Organic binders include, for example, polyolefin-based binders, polyvinyl alcohol-based binders, polyurethane-based binders, polyvinyl chloride-based binders, polyester-based binders, styrene-based binders, and polyvinyl acetate-based binders such as starch, carrageenan, Examples include natural product binders such as xanthan gum, gellan gum, polysaccharides such as alginic acid, and animal proteins such as glue. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more.

  The binder is preferably a water-insoluble binder. Thereby, it can prevent that the structure of the artificial soil particle 50 (50a, 50b) collapses by irrigation etc. Examples of the water-insoluble binder include a resin material. Examples of such resin materials include polyolefin resins such as polyethylene and polypropylene, vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, polyester resins such as polyethylene terephthalate, styrene resins such as polystyrene, acetic acid, and the like. Examples thereof include vinyl and vinyl acetate resins such as ethylene vinyl acetate, polyurethane, and urethane resins such as vinyl urethane. Of these, polyethylene is preferred. Instead of resin materials, polymer gelling agents such as acrylamide, natural polysaccharide gelling agents such as alginate and carrageenan, rubber coating agents such as natural rubber and silicone rubber, etc. can be used. is there. Furthermore, a resin cross-linking agent can also be used. Examples of such resin crosslinking agents include isocyanates, vinyl sulfone compounds, aziridines, dihydrazides, methylated amines, diglycidyl ethers, carbodiimides, formaldehyde, titanium coupling agents, silane coupling agents, and the like.

  The bulk specific gravity of the artificial soil particles 50 (50a, 50b) is set to 0.1 to 0.7 g / cc, preferably 0.2 to 0.6 g / cc. If the bulk specific gravity is in the above range, the nitrifying bacteria 4 are likely to propagate in the voids in the artificial soil particles 50, and the movement of the nitrifying bacteria 4 is easy. If the bulk specific gravity of the artificial soil particles 50 is less than 0.1 g / cc, the proportion of the voids 6 increases and the artificial soil particles 50 become fragile, and the artificial soil particles 50 cannot sufficiently retain moisture. This increases the amount of water that leaks out as gravity water. When the bulk specific gravity of the artificial soil particles 50 exceeds 0.7 g / cc, the proportion of the voids 6 decreases, and the moisture that can be held in the artificial soil particles 50 decreases, and a small amount of moisture is strong in the artificial soil particles 50. The amount of easy-to-use water that can be used by plants is reduced. The void peak diameter of the artificial soil particle 50 is set to 50 nm to 100 μm, preferably 300 nm to 50 μm. Here, the void peak diameter indicates a value of a diameter corresponding to a peak in the distribution of the diameter of the void 6. When the gap peak diameter is less than 50 nm, the size of the gap 6 is reduced, so that the nitrifying bacteria 4 are not taken into the gap 6 and it is difficult for the nitrifying bacteria 4 to move through the gap 6. When the void peak diameter exceeds 100 μm, the size of the void 6 increases and the artificial soil particle 50 becomes brittle. Moreover, the water | moisture content leaked out from the artificial soil particle 50 as gravity water increases.

<Generation of nitrate ions>
Hereinafter, a process of generating nitrate ions will be described with reference to FIGS. 4 and 5. 4 and 5 are explanatory diagrams of the production of nitrate ions in the artificial soil culture medium, respectively. In the explanatory diagram of FIG. 4, nitrate ions are generated by including the first artificial soil particles 50 a and the second artificial soil particles 50 b. Hereinafter, in detail, as shown in (I) of FIG. 4, the artificial soil culture medium 100 includes at least two types of artificial soil particles of the first artificial soil particles 50 a and the second artificial soil particles 50 b. . As shown in (II) of FIG. 4, the nitrifying bacteria 4 exposed on the surface of the second artificial soil particles 50b or the nitrifying bacteria 4 moved to the outside from the second artificial soil particles 50b are in the first artificial soil particles 50a. Contact with incorporated ammonium ions. As shown in (III) of FIG. 4, ammonium ions are oxidized to nitrate ions by nitrifying bacteria 4. As shown in (IV) of FIG. 4, since nitrate ions are anions, they are positively released from the artificial soil particles 50a containing the cation exchanger 1 to the outside.

  FIG. 5 shows a process different from the production of nitrate ions shown in FIG. That is, FIG. 5 is an explanatory diagram of the mechanism by which nitrate ions are generated using root acid as a trigger. Hereinafter, in more detail, as shown in FIG. 5, in the artificial soil culture medium 100, at least two kinds of artificial soil particles of the first artificial soil particles 50a and the second artificial soil particles 50b are mixed. When root acid is discharged from the roots of the cultivated plant 30 to the artificial soil medium 100, the root acid is supplied to the first artificial soil particles 50a in FIG. As shown in FIG. 5 (II), hydrogen ions derived from root acid are selectively exchanged with ammonium ions incorporated into the cation exchanger 1 in the artificial soil particles 50a. The ammonium ions desorbed from the cation exchanger 1 are released from the artificial soil particles 50a. As shown in (III) of FIG. 5, the ammonium ions are oxidized by contact with the nitrifying bacteria 4 existing on the surface or inside of the second artificial soil particles 50b, and as shown in (IV) of FIG. Become an ion. As a result of the production of nitrate ions in the artificial soil culture medium 100 by such a process, nitrate ions are supplied to the cultivated plant 30 as shown in FIG. In addition, the growth of the cultivated plant 30 can be promoted more efficiently by changing the composition of the artificial soil particles 50a and 50b according to the type of the cultivated plant 30 and the cultivation conditions. In the case of this mechanism, even if the artificial soil particle 50 has both the cation exchanger 1 and the nitrifying bacteria 4, nitrate ions are similarly generated.

  The artificial soil medium of the present invention can be used for plant cultivation for ornamental and horticultural purposes, but can also be used for other purposes such as plant factory soil culture medium, molded soil culture medium, and soil improvement. .

DESCRIPTION OF SYMBOLS 1 Cation exchanger 2 Cavity 3 Pore 4 Nitrifying bacteria 5 Inorganic filler 6 Cavity 30 Cultivated plant 50 Artificial soil particle 50a 1st artificial soil particle 50b 2nd artificial soil particle 100 Artificial soil culture medium

Claims (11)

An artificial soil medium capable of converting ammonia nitrogen into nitrate nitrogen,
An artificial soil medium containing at least a cation exchanger capable of supporting ammonium ions and a nitrifying bacterium that oxidizes the ammonium ions into nitrate ions.   The artificial soil medium according to claim 1, comprising artificial soil particles containing the cation exchanger and artificial soil particles containing the nitrifying bacteria.   The artificial soil medium according to claim 2, wherein the artificial soil particles are a porous structure having a bulk specific gravity of 0.1 to 0.7 g / cc and a void peak diameter of 50 nm to 100 μm.   The artificial soil medium according to any one of claims 1 to 3, wherein the nitrifying bacteria contain at least ammonia oxidizing bacteria and nitrite oxidizing bacteria. The ammonia oxidizing bacterium is at least one selected from the group consisting of the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosorobas, Brevibacillus, and Xanthomonas,
The artificial soil medium according to claim 4, wherein the nitrite-oxidizing bacterium is at least one selected from the group consisting of the genus Nitrobacter, Nitrococcus, and Nitrospira.   The artificial soil culture medium according to claim 4 or 5, wherein a ratio of the number of bacteria of the ammonia oxidizing bacteria and the nitrite oxidizing bacteria is 1: 1000 to 10: 1.   The artificial soil medium according to any one of claims 1 to 3, wherein the nitrifying bacteria are heterotrophic bacteria that directly oxidize ammonium ions to nitrate ions.   The artificial soil medium according to claim 7, wherein the heterotrophic bacterium is at least one selected from the group consisting of Arthrobacter, Bacillus, Ocrobacterium, Delftita, and Stentomonas. The artificial soil medium according to any one of claims 1 to 8, wherein the content of the nitrifying bacteria is 10 ⁵ to 10 ⁹ CFU / g.   The artificial soil culture medium according to any one of claims 1 to 9, wherein the maximum water retention amount is 30 cc / 100 cc or more, and the gas phase rate is 20 to 60% when the water retention amount is 30 cc / 100 cc.   The artificial soil medium according to any one of claims 1 to 10, which is used in an environment having a temperature of 10 to 40 ° C and a pH of 4.0 to 7.5.

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