JP6506320B2 - Plant growth mat and method of manufacturing the same - Google Patents

Description

  The present invention relates to a mat for plant growth using a wood culture soil and a method for producing the same.

  Generally, for raising seedlings of paddy rice, a raising box of about 60 cm long and about 30 cm wide is used. To raise the seedlings of paddy rice, after laying the floor soil in a thickness of about several centimeters in the nursery box, make the floor soil contain sufficient water by irrigation, seed the seed meal on the floor soil, and further on it It is done by covering the soil.

  The preparation of such seedlings is complicated and takes time and labor, and the weight of the nursery box, which is covered with a large amount of floor soil, is as large as about 6 Kg, so there is a problem that the physical burden of the work of handling it is large. is there.

  Therefore, instead of floor soil, a lightweight and easy-to-use nursery mat is conventionally used. For example, there are those obtained by processing rock wool, which is an inorganic artificial fiber, into a mat, and those obtained by processing a fibrous synthetic resin (core-sheath type composite fiber) into a mesh with a chaff (Patent Documents 1 and 2). In patent document 2, the core-sheath-type composite fiber which can be decomposed | disassembled naturally is used.

  Moreover, there exist patent documents 3-7 as a prior art document relevant to this invention.

JP-A-2-303421 Unexamined-Japanese-Patent No. 2002-281827 Japanese Patent Application Laid-Open No. 10-130084 JP, 2006-6254, A JP, 2006-239729, A JP-A-11-89422 JP, 2004-166524, A

Hoshi Nobuyuki, Takahashi Chieko, Water absorption characteristics and prevention measures of "Momigara molding mat", Tohoku Agricultural Research 55, 19-20 (2002), [November 24, 2016 search], Internet <URL: http: //www.naro.affrc.go.jp/org/tarc/to-noken/DB/DATA/055/055-019.pdf>

  Since the mat to be laid in the nursery box instead of the floor soil is formed to have the same vertical and horizontal dimensions as the nursery box, it becomes a thin plate having a thickness of about 12 mm to 15 mm.

  Therefore, in the case of a mat formed of rock wool as described in Patent Document 1, there is a problem that the mat is easily broken such as being broken when handled in a miscellaneous manner because it lacks flexibility. In addition, rock wool is difficult to be decomposed, so there is a problem that it accumulates in the paddy field.

  In that respect, as in Patent Document 2, the mat formed of the core-in-sheath composite fiber and rice husk does not adversely affect the paddy field because it is decomposed naturally.

  However, in the mat of Patent Document 2, root penetration is inhibited by the core-in-sheath composite fiber and rice husk, and as a result, rooting occurs (the root of the sprouted seed meal does not enter the mat and the seed meal floats over the covered soil) Is apt to occur (Non-Patent Document 1).

  Therefore, a main object of the present invention is to provide a mat for cultivating a plant, which is lightweight and easy to handle, and can effectively suppress the rooting.

  One of the present invention relates to a mat for plant growth laid in a seedling box. The plant growth mat is composed of two layers in which a soft layer is laminated on a reinforcing layer. And each of the said reinforcement layer and the said weak layer is comprised by the wood piece which is not composted being couple | bonded by the binder containing a polyvinyl alcohol, and the said binder of the said reinforcement layer is core-sheath-type composite fiber. Contains.

  That is, since this plant growth mat is mainly composed of light wood fragments which are not composted, handling is easy, and the burden of the raising work can be reduced. The fiber component of wood is difficult to biodegrade, and can be formed into a predetermined form excellent in water retention and water permeability by appropriately unraveling. Polyvinyl alcohol does not adversely affect the paddy field because it is water soluble and spontaneously degradable.

  The combination of wood fragments and core-in-sheath composite fibers can efficiently further enhance the flexibility and strength of the reinforcing layer.

  In particular, in the wood fragments, a fibrous form consisting of a large number of fibers formed by melting the fiber bundles and a granular form consisting of wood pieces remaining without melting the fiber bundles are mixed and integrated (so that they can not be distinguished from each other) It is preferable to have a form in which they are integrated.

  In this way, it is possible to realize a nursery mat excellent in both water retention and water permeability.

  Furthermore, the pieces of wood constituting the soft layer are pulverized more finely than the pieces of wood constituting the reinforcing layer, and are formed to have a size that passes through a predetermined mesh size within the range of 3 mm to 20 mm. It is preferable to The definition of the mesh size used in the present invention refers to the nominal equivalent of the test sieve defined in JIS Z 8801-1.

  Then, along with effective suppression of rooting, appropriate water retentivity and water permeability can be secured, and good nursery can be performed.

  Another one of the present invention relates to a method for producing a plant growth mat. In the production method, a woody soil forming step of forming softwood by crushing with an extruder to form wood fragments, and a binder containing polyvinyl alcohol and core-sheath type composite fibers are added to the wood fragments and mixed, A step of forming a reinforcing layer base forming a reinforcing layer base, and a soft layer base forming a soft layer base forming a soft layer by adding and mixing a binder containing polyvinyl alcohol to the wood fragments And a forming step of laminating the soft layer base on the reinforcing layer base and forming the soft layer base into a mat shape.

  According to this manufacturing method, it is possible to manufacture an easy-to-handle and high-performance plant growth mat utilizing wood fragments having a specific structure as described above.

  Specifically, in the woody soil formation step, a pre-treatment for roughly crushing the wood with an extruder to form coarse wood fragments, and finely grinding the coarse wood fragments with a cutter mill to form fine wood fragments It is preferable that the crude wood fragments be used for the wood fragments of the reinforcing layer, and the fine wood fragments be used for the wood fragments of the soft layer.

  If so, handling is also easy, rooting can be effectively suppressed, and a mat for plant growth good for raising seedlings with excellent water retention can be manufactured.

  Furthermore, it is preferable that the woody soil formation step includes a reforming step in which the wood pieces are treated with a solution containing ammonium iron citrate.

  Then, since the tannin contained in the wood fragments can be effectively inactivated without being subjected to concentration damage, the seedlings can be stably and favorably grown.

  Further, the woody soil formation step may include a reforming step of treating the wood pieces with a solution containing ammonium iron citrate and iron sulfate.

  Since iron sulfate has high reactivity with tannin, tannin can be inactivated efficiently and effectively if it is used in a range where concentration failure does not occur.

  Furthermore, it is preferable that the molding in the molding step be performed by a high frequency press.

  It may be formed by a hot press, but if it is a high frequency press, it can be formed efficiently in a very short time than a hot press, so it is excellent in productivity.

  According to the mat for plant growth of the present invention, since it is lightweight and easy to handle and the rooting can be effectively suppressed, the burden of the seedling raising work can be reduced and good seedling can be carried out.

It is a schematic sectional drawing of the mat for plant growth. It is the photograph which photographed wood debris. (A) is a wood fragment formed by a hammer mill (magnification: 100 times). (B) is a wood fragment formed by a cutter mill (magnification: 25 times). (C) Wood fragments formed by the extruder (magnification: 25 times). It is a graph which shows the measurement result of three-phase distribution of the wood fragments obtained by the extruder. It is a table | surface which shows the structural example of each of a soft layer and a reinforcement layer. It is the schematic which shows an example of the main processes in the manufacturing method of wood culture soil. It is the schematic which shows an example of the main processes in the manufacturing method of wood culture soil. It is the schematic which shows an example of the manufacturing equipment of the mat | matte for plant growth. It is the photograph which copied the wood debris obtained by grind | pulverizing the crushed material of an extruder by changing the mesh size of a screen. (A) is a wood fragment having a mesh size of 2 mm (magnification: 25 times). (B) is a wood fragment with a mesh size of 3 mm (magnification: 25 times). (C) is a wood fragment having a mesh size of 4 mm (magnification: 25 times). It is a graph which shows the measurement result of three-phase distribution of the wood fragments obtained by grind | pulverizing the crushed material of an extruder by changing the mesh size of a screen. (A) is a wood fragment of 2 mm in mesh size. (B) is a wood fragment of 3 mm mesh size. (C) is a wood fragment with a mesh size of 4 mm. It is a figure showing the result of comparative examination 1. It is a figure which shows the result of the comparison test 2. FIG. It is a figure which shows the result of the comparison test 3. FIG. It is a figure showing the result of comparative examination 4. It is a figure which shows the result of the comparison test 5. FIG.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. However, the following description is merely illustrative in nature, and does not limit the present invention, its application, or its application.

<Plant growth mat>
FIG. 1 shows an example of a mat for growing seedlings of a rice plant (an example of a plant) to which the present invention is applied (hereinafter, also referred to as a seedling mat 1). Seedling mat 1 is a general seedling box (approximately 60 cm in length, 30 cm in width, 3 cm in height, 3 cm in height), so that it can be laid in place of floor soil; It has a thickness of 5 to 1.5 cm and is formed in a flat plate shape.

  The seedling mat 1 is usually packaged in a cardboard box or the like in a stacked state and provided to the market. The seedling mat 1 provided in this way is laid in a seedling box and used for raising rice seedlings. A seedling is sown on the seedling mat 1 laid in a seedling box, and then the seedling mat 1 is covered with a predetermined amount of soil after the seedling mat 1 is filled with sufficient water by irrigation. Storage is carried out by storing seedling boxes set in such a manner under predetermined conditions, and germinating the seed meal. The structure of the seedling mat 1 is devised so that the series of operations can be appropriately and easily performed and good seedling can be carried out.

  That is, the raising seedling mat 1 is comprised by two upper and lower layers by which 1 A of soft layers are laminated | stacked on reinforcement layer 1B. Reinforcement layer 1B is provided mainly for giving soft and hard-to-break strength to nursery mat 1 and facilitating handling, and soft layer 1A suppresses the rise of roots which may occur in the early germination stage of seed meal, The main objective is not to inhibit the proper growth of seedlings.

  The wood raising soil developed by the present inventors is used for the seedling mat 1 of the present embodiment (details will be described later). That is, each of the reinforcing layer 1B and the soft layer 1A of the seedling mat 1 of the present embodiment is porous by bonding the wood fragments 2A and 2B related to the woody soil with a binder containing polyvinyl alcohol (PVA) It is organized in quality structure. For example, about 3% PVA can be included by bone dry weight ratio to wood pieces 2A and 2B which constitute each layer 1A and 1B.

  By constructing the raising seedling mat 1 with lightweight wood fragments 2A and 2B, handling is easy and the burden of raising seedling work can be reduced. PVA is water soluble and naturally degradable, so it does not adversely affect the paddy field.

  The wood fragments 2A and 2B, which will be described later in detail, are a mixture of a fibrous form consisting of a large number of fibers formed by melting the fiber bundles and a granular form consisting of wood pieces remaining without melting the fiber bundles. It has a unique structure integrated. Since the form is excellent in water retention, it is effective as a substitute for floor soil.

  Furthermore, coarser wood pieces (rough wood pieces 2B) are used for the reinforcing layer 1B, and homogeneous and fine wood pieces (fine wood pieces 2A) classified to a predetermined size are used for the soft layer 1A. Is preferred. Specifically, it is preferable to form the fine wood pieces 2A constituting the soft layer 1A in a size that passes a predetermined mesh size within the range of 1 mm to 10 mm. By doing so, appropriate water retentivity and water permeability can be secured, as well as effective suppression of rooting, and good nursery can be performed.

  In particular, the binder of the reinforcing layer 1B additionally includes core-sheath composite fibers 3 (known). For example, core-sheath type composite fiber 3 of about 0.5% by bone dry weight ratio can be included in crude wood pieces 2B constituting reinforcing layer 1B. Thereby, flexibility and strength are further strengthened by combination with the unique structure of the wood fragments 2B, and stability is improved. As in the case of the core-sheath composite fiber of Patent Document 2, it is preferable to use a naturally decomposable core-sheath composite fiber also in this nursery mat 1.

  On the other hand, in the raising seedling mat 1 of the present embodiment, the core-sheath type composite fiber 3 is not contained in the binder of the soft layer 1A, and the fine wood fragments 2A are bonded only by PVA. The configuration of the soft layer 1A can be appropriately selected according to the specification, and may include the core-sheath type composite fiber 3. However, in such a case, the amount of core-sheath composite fiber 3 added to soft layer 1A is preferably equal to or less than that of reinforcing layer 1B.

  The thickness of each of the reinforcing layer 1B and the soft layer 1A can be appropriately selected according to the specification. For example, the thickness of the nursery mat 1 may be adjusted in the range of 1 mm to 15 mm in a range lower than the height of the nursery box. As an example, in the raising seedling mat 1 of this embodiment, the thickness of each of the reinforcement layer 1B and the soft layer 1A is 5 mm.

  In addition, the reinforcing layer 1B and the soft layer 1A may contain additional materials such as a surfactant and a fertilizer, or a wood-based soil containing these additional materials may be used.

<Woody soil>
At present, in agriculture and horticulture, cultivated soil composed mainly of peat moss, akadama and compost is generally used. Cultivated soil is required to have qualities such as water retention, permeability, pH, etc. suitable for the plant to be planted, as well as nutritional components. So-called organic materials such as peat moss are used for the purpose of improving or improving the water retention and air permeability of the soil. In recent years, since gardening as a hobby has become well established, lightness is also regarded as important for light users who enjoy it. Compost is effective as a soil improvement material (fertilizer), but its production requires long storage time and a large storage area. In addition, "cultivation" is a conceptual thing and means the raw material which comprises the foundation for cultivating a plant.

  Peat moss is a fossilized substance such as water mash, and is excellent as an organic material for soil improvement, but it is not a renewable resource, and its cost is also rising. Therefore, in recent years, utilization of wood bark has been studied as a renewable and inexpensive alternative material, and utilization of coconut shell materials using coconut husk as a raw material has been considered. However, vegetable fibers in which such humus is immature contain a large amount of tannin (a mixture that produces polyhydric phenolic acids such as gallic acid by hydrolysis) and a large amount of salt, which hinders the growth of plants. There is. For this reason, it has been carried out for a long time to open the field, expose to rain water, or immerse it in a water tank to remove tannins and salt content, but it takes time and effort and does not perform appropriate management. Variations in quality occur. Then, when using these vegetable fibers as a culture soil, the method of making a tannin react with an iron ion and inactivating it is proposed (refer patent document 6, 7).

  Under such circumstances, the inventors of the present invention diligently studied to develop a culture soil capable of meeting these needs by utilizing wood offcuts. As a result, they found a manufacturing method by which a wood culture soil of good quality can be stably obtained, and developed a new culture soil (wood culture soil, fine wood fragments 2B here) replacing them. The details will be described below.

(Raw material for wood growing soil)
Wood-based soil is composed of fine wood chip-like wood fragments which are not composted, and its main raw material is softwood wood.

  Here, non-composting means that polysaccharides etc. which comprise wood are not biodegraded by ripening. Although the wood-based soil is fragmented, the fiber components of wood mainly composed of cellulose remain almost intact. Since the fiber component of wood is difficult to biodegrade, as described later, cultivation conditions suitable for the plant to be grown by crushing the wood and forming into pieces of wood of a predetermined form having different water retention and permeability. The soil can be maintained over a long period of time.

  As a raw material of woody soil, domestic conifers such as cedar and cypress are preferable. Because hardwoods are more susceptible to ripening than conifers, they are less stable in quality than softwoods. If it is a softwood, it is hard to ripen, so an appropriate and stable pF value (an index showing the amount of water in the soil that can be absorbed by plants to grow) and three-phase distribution (solid phase, liquid phase, gas phase) It can be maintained for a long time.

  Furthermore, domestic conifers are widely used for building materials, wood processing materials, etc., and a large amount of scraps (excessive pieces of wood) are generated during their manufacture. Since the offcuts can be used as a raw material for wood growing soil, inexpensive raw materials can be stably secured.

  Tannin is abundantly present in the wood, especially in the bark, but also in the inner sapwood (the periphery of the tree) and the heartwood (the central portion of the tree). And, the heartwood tends to have a higher content of tannin than the sapwood. Therefore, it is preferable to use more sapwood as the raw material than the core material. It is preferable to set the ratio of the wood used as a raw material so that the ratio of a sapwood and a core material becomes the range of 1: 0 to 1: 1 specifically ,. In particular, the lower the proportion of heartwood, the better.

  Sapling offcuts are generated in large quantities as backing plates or processed offcuts when lapping columns and the like. By preferentially using such a sapwood offcut, the proportion of the sapwood can be increased. In addition, in the production of plywood and laminates, there is a process of peeling logs having a predetermined size in the lengthwise direction and forming a thin plate in the circumferential direction from the outer periphery to the predetermined thickness in order to form a thin plate. The proportion of sapwood can be increased by using the first peel start of the process. On the other hand, it is possible to reduce the proportion of the core material by removing from the raw material of the wood-based soil the end material consisting of the central portion of the log, which is left last and which is called a peeling core. In addition, since the percentage of sapwood in the trunk increases as the age of young trees increases, the percentage of heartwood can be reduced by using thinned wood compared to when large diameter trees are used. Thus, the ratio between the core material and the sapwood can be adjusted.

  For woody soils, as an auxiliary raw material, modifiers consisting of ammonium iron citrate and iron sulfate for the purpose of inactivating tannins contained in wood, surfactants for the purpose of improving the quality and pH adjustment Agents are added.

  Iron sulfate, specifically ferrous sulfate etc., is effective for inactivating tannins because it has high reactivity with tannins, but if added in excess, it causes plant growth inhibition It turned out (details will be described later). Specifically, it has been found that if the concentration of iron sulfate added to wood fragments is greater than 0.2% by weight based on the dry weight of wood fragments, it may cause plant growth inhibition.

  On the other hand, although ammonium citrate is less reactive with tannin than iron sulfate, it does inhibit plant growth even when added at a high concentration of 0.5% by weight based on the bone dry weight of wood fragments I was not able to admit. From this, it was found that ammonium iron citrate is effective as a modifier for wood culture soil.

  Therefore, it is preferable to add an amount of ammonium iron citrate capable of sufficiently inactivating the tannin contained in the wood fragments as a modifier for inactivating the tannin to the woody soil. Furthermore, it is more preferable to add an amount of iron sulfate which does not cause plant growth inhibition and an amount of ammonium iron citrate which is capable of sufficiently inactivating the deficiency of tannin. Therefore, in this woody soil, iron sulfate and ammonium iron citrate are used in combination.

  Wood fragments are rendered water repellent by drying. If the woody soil is constituted by wood fragments having water repellency, the water retentivity is deteriorated and the water repellant causes the water distribution to be inhomogeneous, which may cause the growth inhibition of the plant. On the other hand, it turned out that the effect which suppresses growth inhibition of the plant by drying is acquired by adding surfactant to a wood fragment (the detail is mentioned later).

  In addition, plants generally prefer mildly acidic to neutral pH, but each has a suitable pH. Therefore, in this woody soil, a pH adjuster according to the plant to be grown is added as an auxiliary raw material. For example, calcium carbonate as an alkalinity adjusting agent, peat moss as an acidity adjusting agent, etc. are added to the woody soil according to the specification. In order to cope with other fertilizer components and various environmental changes, lightweight aggregate, such as charcoal, bentonite, and zeolite, may be added.

(Structural characteristics of wood growing soil)
Woody soil is composed of fine wood chip-like wood fragments in which the fiber component of wood remains almost unchanged, and is set in a form according to the plant to be grown. Specifically, the degree of melting of the fiber component of wood is set according to the specification. As the fiber content dissolves, the water retention and water absorption tend to be high, and as the wood structure remains, the water permeability (water drainage) tends to be high.

  As a method of crushing the wood as a raw material, for example, a method of finely cutting the wood by a cutting and crushing machine such as a rotary saw and a cutter mill (cutting and crushing), a method of crushing the wood by impact by an impact crushing machine such as a hammer mill and a pin mill (Impact grinding) There is a method (grind grinding) of grinding wood with a grinding grinder such as an extruder or a ball mill. Among these, since grinding and crushing is the easiest to dissolve the fiber content, water retention and water absorption can be increased by crushing wood by grinding and crushing.

  For example, a disc refiner is known as an apparatus capable of finely separating wood fibers. However, the disc refiner is not only large in equipment itself, but also needs steaming equipment, resulting in an increase in equipment size. Therefore, the disc refiner is excessive for practical use as a production facility for wood growing soil, and its adoption is difficult. Furthermore, since the pulverized material is highly fiberized, it causes excessive water absorption and lack of an air layer, and there is also a problem that it can not be said that it is suitable for plant growth.

  On the other hand, an extruder like the twin screw extruder of Patent Document 5 is small in size, relatively simple in structure and easy to handle, and the ground matter can not be recognized in other grinders. Because it has a unique structure that is suitable for

  FIG. 2 shows the wood fragments formed by each method. (A) is a wood fragment formed by a hammer mill, and (b) is a wood fragment formed by a cutter mill. And (c) is a wood fragment formed by the extruder.

  The wood fragments formed by the cutter mill have a low aspect ratio (ratio of longitudinal and lateral sizes), are in the form of massive or granular, fiber bundles remain as they are, and hardly fiberized. On the other hand, although wood fragments formed by a hammer mill have a high aspect ratio and fiberization can be seen compared to the case of a cutter mill, their form does not leave a massive or granular form zone.

  On the other hand, wood fragments formed by the extruder have a form (fibrous form) consisting of a large number of filamentous fibers formed by disentanglement of fiber bundles (such as small pieces of wood with fiber bundles remaining unbroken) Forms (granular forms) etc. are recognized, and these forms form a complex form with a high aspect ratio, in which they are appropriately mixed and integrated (in a state where they are integrated so that they can not be distinguished from each other). Therefore, the wood fragments obtained by the extruder have a structure effective for both water retention and water permeability, since they contain both fibrous forms effective for water retention and particulate forms effective for water permeability. In addition, MORI-LEHAMANN extruder (type B90) made by Mori Machinery Co., Ltd. was used for the extruder.

  However, since the wood fragments obtained by the extruder were, in fact, coarse in shape, it was found that although the water permeability is good as the woody soil, the water retention is bad. FIG. 3 shows the measurement results of the three-phase distribution. The liquid phase serving as an indicator of the water retention capacity of wood fragments obtained by the extruder was about 60%.

  The soil is composed of a solid phase (that is, the solid portion of the soil), a liquid phase (that is, the water held by the soil), and a gas phase (that is, the air contained in the soil). Distribution is three-phase distribution. The measurement of three-phase distribution is performed by a known three-phase distribution measuring device.

  In addition, since the pieces of wood obtained by the extruder (rough pieces of wood 2B) have large variations in size and shape, the water permeability tends to be unstable. There is also a problem that when there are large sized pieces of wood in the form of particles, the seeds sown will fall between the large pieces of wood and become clogged during cultivation, resulting in uneven germination. Furthermore, there is a problem that fibrous wood fragments and entangled wood fragments are entangled and tend to be large lumps, making it difficult to handle as a culture soil (this point, the reverse applied to reinforcement layer 1B of nursery mat 1) ).

  Therefore, since the wood fragments crushed only with the extruder had room for improvement, the present inventors diligently studied. As a result, the present inventors do not break the unique structure in which the fibrous form and the granular form are appropriately mixed and united, even if the wood pieces crushed by the extruder are crushed by the cutter mill. They found that they could be refined, and developed wood fragments having a homogeneous, fine and unique structure.

  Thus, the wood fragments constituting this woody soil not only have a structure in which the fibrous form and the granular form are appropriately mixed and united, but also pass, for example, each mesh of 1 mm to 20 mm. It is in a state of being fine and uniform in size.

  It is possible to reduce the size of the ground material obtained in the extruder by narrowing the space between the extruder screw and the axial hole containing the screw (the space through which the wood passes). However, in this case, the progress of fiberization reduces the granular form, so that the structure in which the fibrous form and the granular form are appropriately mixed and integrated is lost.

  It is also possible to mix wood fragments finely ground with a disc refiner with wood fragments finely ground with a cutter mill. However, also in that case, since the structure of each piece of wood is independent of the fibrous form and the particulate form, it is essentially different from the structure in which the fibrous form and the particulate form are mixed and integrated. , Similar homogeneity can not be obtained.

(Component characteristics of wood growing soil)
Iron sulfate is highly reactive with tannins and is added in an insufficient amount to tannins contained in the wood fragments, so it remains in the wood fragments or remains in a trace amount. On the other hand, ammonium iron citrate has low reactivity with tannin because iron ions form a chelate, the total amount added does not react, and ammonium iron citrate remains in the wood fragments . As a result, the wood fragments contain ammonium iron citrate (i.e. ammonium iron citrate can be detected from wood chips).

  Similarly, since the surfactant and the pH adjuster are also added, the wood fragments also contain these.

(Configuration example of nursery mats)
In FIG. 4, the structural example of each of the soft layer 1A and the reinforcement layer 1B of the nursery mat 1 is shown. As the main component of the reinforcing layer 1B, coarse wood fragments 2B (ground product by extruder) obtained in the production process of woody soil are used, and they are mat-like by bonding with a core-sheath composite fiber 3 and a binder containing PVA. It is formed by molding. Reinforcing coarse wood fragments 2B that are easily entangled with core-sheath type composite fiber 3 (small amount is sufficient), they are superior in water retention and water permeability compared with other general materials, and only suitable for raising seedlings It has a flexible, strong and durable structure.

  On the other hand, the configuration of the soft layer 1A can be appropriately selected depending on the plant to be grown. As in the case of the seedling mat 1 of this embodiment, the soft layer 1A (pattern 1) is mainly formed of fine wood fragments 2A and is bonded with PVA and formed into a mat shape, it is extremely excellent in water retention and water permeability. In addition, since a more homogeneous and fine porous structure is formed, rooting can be effectively suppressed.

  In order to enhance the strength, the binder of the soft layer 1A may also contain the core-sheath type composite fiber 3 (pattern 2). In addition, it is soft and weak mainly composed of fine granular pulverized material classified to a size passing through a predetermined mesh size in the range of 1 mm to 10 mm as other pulverized wood materials, for example, a pulverized material by a cutter mill. The layer 1A may be configured (patterns 3 and 4). In this case, since good water permeability can be obtained, it is possible to suppress the rise of roots and achieve good growth of plants suitable for such a medium.

  In some cases, the soft layer 1A may be composed mainly of a mixture of fine wood fragments 2A and other crushed wood products. By doing so, the water retentivity and the water permeability can be adjusted, so the versatility is excellent.

<Production method of nursery mats>
The method of producing the raising seedling mat 1 is a step of crushing softwood wood with an extruder to form pieces of wood (woody soil formation step), adding a binder containing PVA and core-sheath type composite fibers to the pieces of wood A step of mixing and forming a reinforcing layer base forming a reinforcing layer (reinforcing layer base forming step), adding a binder containing PVA to wood pieces and mixing to form a soft layer base forming a soft layer The soft layer base is laminated on a step (soft layer base forming step), the reinforcing layer base, and formed into a mat shape (molding step).

(Woody soil formation process)
In this step, the above-described woody soil (fine wood fragments 2A) is formed together with the crude wood fragments 2B. Woody soil is manufactured through a process (first process) of crushing softwood lumber (swarf) to form wood fragments, and a process (second process) of processing the obtained wood fragments with a solution. It can be industrially manufactured using uncomposted wood as a raw material, so it can be mass-produced in a short time.

  In the first step, a pre-treatment to roughly pulverize the end material with an extruder and a post-treatment to finely grind with a cutter mill are performed. As the extruder, for example, a twin-screw crusher as disclosed in Patent Document 5 can be used. There are various types of cutter mills, for example, SF-4 manufactured by Three Forces Co., Ltd. can be used.

  First, the offcuts are crushed in an extruder and the wood fragments thus obtained are further crushed in a cutter mill. Although grinding may be performed separately, it is preferable from the viewpoint of efficiency to simultaneously grind continuously.

  Then, the wood fragments obtained by roughly crushing with an extruder (crude wood fragments 2B) are used for wood fragments constituting the reinforcing layer 1B, and further obtained by finely grinding with a cutter mill (fine wood fragments (fine wood) The fragments 2A) are used for wood fragments constituting the soft layer 1A (hereinafter, these are collectively referred to as "wood fragments").

  The cutter mill is usually provided in a replaceable state with a screen in which pores of a predetermined size are formed in order to classify and discharge finely pulverized wood fragments. It is preferable to set the mesh size in the range of 1 mm to 20 mm, more preferably in the range of 3 mm to 20 mm, for the production of woody soil. This is because the use of a mesh less than 3 mm in size significantly reduces the classification efficiency. In this case, it is easy to handle, and it is possible to obtain a good quality wood culture soil with high water retention.

  In the second step, inactivation of tannins contained in wood fragments and modification treatment for the purpose of improving the quality are performed. Specifically, treatment is performed in which predetermined amounts of iron sulfate, ammonium ammonium citrate, a surfactant, a pH adjuster, and the like are applied to wood pieces.

  Iron sulfate is effective for inactivation due to its high reactivity with tannins, but when added in excess, it causes plant growth inhibition. Therefore, 0.2% by weight or less of iron sulfate is applied to the wood fragments with respect to the bone dry weight of the wood fragments as an amount that does not cause growth inhibition of plants. Thereby, the entire amount of iron sulfate reacts with the tannins of the wood fragments to inactivate the tannins. As a result, unreacted iron sulfate does not remain in the woodland soil or remains even if it remains in a trace amount (the growth inhibition of the plant does not occur).

  On the other hand, the amount of iron sulfate is insufficient relative to the amount of tannin contained in the wood fragments. Therefore, the amount is not more than 0.5% by weight based on the bone dry weight of the wood fragments, as an amount sufficient for inactivation of the remaining tannin, which does not cause the growth inhibition of the plant even if it remains. Let it work. By so doing, tannin can be effectively inactivated and plant growth inhibition can be prevented.

  In addition, it is common to make iron sulfate and ammonium ammonium citrate act on wood fragments in an aqueous solution, but at that time, if it is only iron sulfate, it tends to precipitate, so the concentration is not stable. is there. On the other hand, when ammonium iron citrate is added to an aqueous solution of iron sulfate, precipitation is less likely to occur and there is also an advantage that the concentration of iron sulfate is stabilized.

  Moreover, the process which makes the predetermined amount of each surfactant and a pH adjuster act on a wood fragment is performed. Thereby, the plant to be grown (here, rice) can be modified to a more suitable state, and the growth of the plant can be promoted.

  In the second step, each component may be made to act on the wood fragments by immersing the wood fragments in a water tank containing the reforming solution, but in order to be able to mass-produce efficiently, a process of spraying the reforming solution is performed Is preferred. An example is shown in FIGS. 5A and 5B.

  Since it is sufficient to cause each component to act on a predetermined amount of wood fragments, as shown in FIG. The modification processing can be performed by spraying a predetermined amount of the reformed liquid, which has been adjusted, with the spray 13 (batch type). According to this method, each component can be uniformly applied to a large amount of wood fragments 10 in a short time.

  Further, as shown in FIG. 5B, the wood fragments 10 supplied in a fixed amount from the feeder 14 are conveyed by the belt conveyor 15, and the modifying solution in which the content of each component is adjusted is sprayed by the belt conveyor 15. A predetermined amount is sprayed toward the wood fragments 10 to be conveyed. Also by doing so, the reforming process of the wood fragments 10 can be uniformly performed. According to this method, since the reforming process can be continuously performed, mass production can be realized. In addition, the spraying of the reforming solution may be collectively performed once. In addition, it may be made uniform while being stirred after or during spraying of the reforming solution.

  As described above, according to the method of spraying the reforming solution, each component can be uniformly applied to wood pieces in a short time. Since the amount of the reforming solution is sufficient, it is extremely efficient. If the reforming solution is heated (for example, 50 ° C. or more) at the time of spraying, the removal of water can be promoted, and the treatment can be performed more efficiently.

(Reinforcement layer base formation process, soft layer base formation process, molding process)
An example of the manufacturing equipment which performs these processes is shown in FIG. This production facility is a production facility based on a dry process, and is simplified as compared to a production facility based on a wet process. The reinforcing layer base forming step, the soft layer base forming step, and the forming step are continuously performed.

  The manufacturing equipment includes a conveyor 21, a first hopper 22, a first feeder 23, a second hopper 24, a second feeder 25, a high frequency press 26, and the like. The first hopper 22 is attached to the first feeder 23, and the second hopper 24 is attached to the second feeder 25. The first feeder 23 is disposed upstream of the second feeder 25 in the transport direction of the conveyor 21. The high frequency press 26 is disposed downstream of the second feeder 25 in the transport direction of the conveyor 21.

  The crude wood pieces 2B are uniformly mixed with a binder containing PVA (powder) and core-sheath composite fibers 3 at a predetermined blending ratio. By doing so, reinforcement layer base HB which constitutes reinforcement layer 1B is formed (reinforcement layer base formation process). At this time, in order to uniformly disperse the core-in-sheath composite fiber 3 in the mother wood pieces 2B, the moisture content of the mother wood pieces 2B is adjusted to 40% or more.

  Similarly, the fine wood fragments 2A are uniformly mixed with a binder containing PVA (powder) at a predetermined blending ratio. By doing so, the soft layer base NB constituting the soft layer 1A is formed (soft layer base forming step).

  The reinforcing layer base HB is loaded into the first hopper 22, and the soft layer base NB is loaded into the second hopper 24. Then, when the conveyor 21 operates, the reinforcing layer base HB of a predetermined amount is sent out in layers on the conveyor 21 by the first feeder 23 in accordance with the transport speed of the conveyor 21. Then, on the reinforcing layer base HB conveyed by the conveyor 21, a predetermined amount of soft layer base NB is fed out in layers by the second feeder 25 in accordance with the conveying speed of the conveyor 21.

  The soft layer base NB is stacked on the reinforcing layer base HB and conveyed to the high frequency press 26 so that the reinforcing layer base HB and the soft layer base NB are continuously high frequency pressed and formed into a mat shape. It is molded. The forming apparatus may not be the high frequency press 26, but may be a hot press (heating and pressing), but in the case of the hot press, it takes about 30 minutes of processing at 160 ° C. for forming. On the other hand, since the high frequency press 26 can be formed in about 1 minute, the productivity is excellent.

(Effect of nursery mats)
As a result of raising seedlings of rice using the seedling mat as described above, it was possible to suppress the occurrence rate of rooting to about 10%.

  In addition, rice was planted by actually planting rice using the seedlings of the paddy rice raised using the nursery mat as described above. The transplanting accuracy of planting was also 10% or less, and the adaptability of the nursery mat to the rice transplanter was also good. Heading and yield were not significantly different from conventional floor soil raising.

  Therefore, according to the mat for plant growth of the present invention, since it is lightweight and easy to handle and the rooting can be effectively suppressed, the burden of the seedling raising work is reduced and good seedling can be carried out.

<Examination of pulverization of crushed wood by extruder>
The contents examined about the refinement of crushed wood by extruder will be explained. The crushed product of the extruder shown in (c) of FIG. 2 and FIG. 3 was finely ground with a cutter mill (SF-4) with the screen mesh size set to 2 mm, 3 mm and 4 mm. Then, by passing through each screen, classified and discharged wood fragments were obtained. Three-phase distribution was measured for these wood fragments.
These forms are shown in FIG. (A) is a wood fragment of 2 mm in mesh size, (b) is a wood fragment of 3 mm in mesh size, and (c) is a wood fragment of 4 mm in mesh size.

  It can be seen that all wood fragments maintain a unique structure in which the fibrous form and the granular form are properly mixed and integrated. And, the size is classified to the size according to the mesh size.

  Therefore, the fibrous form and the granular form are obtained by further grinding the scraps with an extruder and further grinding with a cutter mill while appropriately selecting the wood fragments obtained in the screen mesh size in the range of 1 mm to 20 mm. It is possible to stably obtain homogeneous and fine wood fragments having a unique structure in which the form is appropriately mixed and integrated.

  The measurement result of three-phase distribution of these wood fragments is shown in FIG. (A) is a wood fragment of 2 mm in mesh size, (b) is a wood fragment of 3 mm in mesh size, and (c) is a wood fragment of 4 mm in mesh size.

  In all wood fragments, the liquid phase was 70% or more, which was significantly increased from about 60% of the liquid phase of the wood fragments obtained by the extruder. Accordingly, it was found that the water holding capacity was improved, and a good quality wood culture soil was obtained (suitable for raising rice seedlings).

  Homogenization, refinement, and improvement of water retention are also advantageous for the inactivation of tannin. That is, since it becomes easy to distribute the aqueous solution of iron salt uniformly on wood fragments, it is possible to efficiently inactivate tannin with a necessary and sufficient iron salt. In particular, it is effective when spraying an aqueous solution of iron salt.

<Examination of inactivation of tannin>
Next, the contents examined about inactivation of tannin will be described.

(Comparative test 1)
The effects of iron sulfate and ammonium ferric citrate on plant growth were investigated. In the test, aqueous solutions of iron sulfate and ammonium iron citrate adjusted to have the same value (approximately 0.5 μS / cm) of electric conductivity (EC) were prepared, and each was applied to filter paper covered with individual petri dishes. The aqueous solution was added. After seeding about 12 seeds of Komatsuna seeds on each filter paper, the seedlings were raised for about 7 days under dark conditions.

  The results are shown in FIG. In iron sulfate, poor germination was observed, but in iron ammonium citrate, poor germination was not observed. From this result, it was found that iron sulfate is less likely to cause growth inhibition of plants due to its own presence, whereas iron sulfate causes growth inhibition of plants due to its own presence.

(Comparative test 2)
The effects of iron sulfate and ammonium ferric citrate on plant growth in the presence of tannin were investigated. In the test, aqueous solutions of iron sulfate and ammonium iron citrate are prepared at respective concentrations of 125 ppm and 500 ppm, 400 ppm of tannic acid is added to these, and the same test as comparative test 1 is performed. The developmental states were compared.

  The results are shown in FIG. In the figure, (a) is a test result of a blank (only 400 ppm of tannic acid). (B1) is a test result with tannic acid 400 ppm + iron sulfate 125 ppm, and (b2) is a test result with tannic acid 400 ppm + iron sulfate 500 ppm. (C1) is a test result with tannic acid 400 ppm + ammonium ion citrate 125 ppm, (c 2) is a test result with tannic acid 400 ppm + iron ammonium citrate 500 ppm.

  From (a) of FIG. 10, it can be seen that almost no root hair is observed in the presence of tannic acid alone, and growth is inhibited (the same result has been confirmed even at a concentration of about 200 ppm). On the other hand, according to (b1) and (c1) of FIG. 10, in the test section where each iron salt was added at a concentration of 125 ppm to 400 ppm tannic acid, root hairs were observed and growth inhibition by tannic acid was suppressed. It can be understood that That is, by adding an iron salt of about 125 ppm to 400 ppm of tannic acid, it is possible to prevent the growth inhibition of plants by tannin.

  On the other hand, according to (b2) in FIG. 10, in the test section where iron sulfate was added at an excess of 500 ppm to 400 ppm tannic acid, almost no root hair was observed, whereas in (c2) in FIG. In the test section where ammonium ferric citrate was added at an excess of 500 ppm with respect to tannic acid, root hairs were observed. That is, iron sulfate has a concentration disorder, and its excessive addition causes plant growth inhibition, whereas ammonium citrate does not show a concentration disorder, and even if it is added excessively, the plant growth It turned out that the possibility of causing inhibition is low.

(Comparative test 3)
The effect of the spray of the reforming solution was examined. In the test, iron sulfate and ammonium ferric citrate modifier solutions are prepared separately by weight% (0.1, 0.3, 0.5) with respect to the bone dry weight of wood pieces, and these are sprayed on wood pieces The changes in polyphenol content were compared. The amount of tannin was determined by measuring the amount of polyphenol using the Folin-Ciocalteu method.

  The results are shown in FIG. No significant difference was observed depending on the type and concentration of iron salt, and the polyphenol content decreased in all the test sections compared to the blank (no treatment). Therefore, it was found that it is possible to inactivate tannin by spraying wood chips with a modification solution containing an iron salt.

(Comparative test 4)
The effects of the combination of iron sulfate and ferric ammonium citrate were investigated. In the test, wood chips were produced by crushing Sugi chips (from Tokushima) dried at 70 ° C. for 3 days with a cutter mill (screen diameter 2 mm). The wood fragments were sprayed with a modification solution containing 0.5% by weight of ammonium iron citrate and iron sulfate of different concentrations with respect to the bone dry weight, and woody soil with different spray contents of iron sulfate Made. Using these woody soils, a seedling test of Komatsuna was conducted, and the yield after 35 days from sowing was compared.

  The test results are shown in FIG. High yield was obtained in the test area where 0.2% by weight or less of iron sulfate coexists with respect to the bone dry weight of wood fragments, including the test area with 0.5% by weight of ammonium ferric citrate alone, In the test area in which iron sulfate of more than 0.2% by weight with respect to the bone dry weight of wood fragments co-existed, a decrease in yield was observed.

  Therefore, by causing at least 0.5% by weight or less of ammonium iron citrate to act on the wood fragments with respect to the bone dry weight of the wood fragments, a growth inhibition by tannin can be suppressed, and a woody soil that can grow plants well You can get it. Moreover, the growth inhibition by tannin is also suppressed by using 0.2% by weight or less of iron sulfate with respect to the bone dry weight of wood pieces in combination with a sufficient amount of ammonium iron citrate to act on the wood pieces. It is possible to obtain a woody soil that can grow plants well.

(Comparative test 5)
It investigated about the effect by addition of surfactant. In the test, wood fragments were prepared in the same manner as in Comparative Test 4, and two samples of woody soil (only one section) to which woodwood was added with a modifying solution consisting of ammonium citrate alone, iron sulfate and iron citrate Two samples of wood-based soil (a combined use area) to which a modifying solution in combination with ammonium was added were prepared. An appropriate amount of surfactant (Cymato EZ: manufactured by Tomo Green Chemical Co., Ltd.) was added to the modifying solution of one sample of each woody soil. Using the prepared samples, a nursery seedling test of Komatsuna was conducted under the same conditions.

  The test results are shown in FIG. It was found that the addition of the surfactant increased the yield and the addition of the surfactant was effective for the growth of plants in any of the samples of the single zone and the combination zone.

  In addition, the mat for plant growth concerning this invention is not limited to embodiment mentioned above, Also the other various structure is included. For example, the size of the mat can be changed appropriately according to the specification. The extruder is not limited to two axes but may be one axis or three or more axes. Not limited to rice, it may be used to cultivate other plants.

1 Seedling mat 1A Soft layer 1B Reinforcement layer 2A Fine wood debris 2B Coarse wood debris 3 Core-sheath composite fiber

Claims (7)

A mat for plant growth,
It consists of two layers where a soft layer is laminated on a reinforcing layer,
Before Symbol soft layer is constituted by wood debris that are not composted is coupled with a binder comprising polyvinyl alcohol,
The reinforcing layer is formed by bonding uncomposted wood fragments with a binder containing polyvinyl alcohol and core-sheath composite fibers ,
The pieces of wood constituting the soft layer are pulverized more finely than the pieces of wood constituting the reinforcing layer, and are formed to pass a mesh of a predetermined size within a range of 3 mm to 20 mm. Plant mats. In the plant growth mat according to claim 1,
A plant in which the wood fragments have a form in which a fibrous form consisting of a large number of fibers formed by melting fiber bundles and a granular form consisting of wood pieces remaining unmelted are united together Mat for growth. A method of manufacturing a mat for plant growth, comprising
A woody soil formation process of crushing softwood wood with an extruder to form wood fragments;
A reinforcing layer base forming step of forming a reinforcing layer base constituting a reinforcing layer by adding a binder containing polyvinyl alcohol and core-sheath type composite fibers to the wood fragments and mixing them;
A soft layer base forming step of adding a binder containing polyvinyl alcohol to the wood pieces and mixing them to form a soft layer base constituting a soft layer;
Forming the soft layer base on the reinforcing layer base and forming the soft layer base into a mat shape;
Only including,
A manufacturing method of forming a size of passing a mesh of a predetermined size within the range of 3 mm to 20 mm by grinding the wood fragments constituting the soft layer finer than the wood fragments constituting the reinforcing layer . In the manufacturing method according to claim 3,
The woody soil forming process is
Pre-treatment to coarsely grind the wood with an extruder to form coarse wood fragments;
Post-treatment to form fine wood fragments by finely grinding the crude wood fragments with a cutter mill;
Including
The manufacturing method wherein the coarse wood fragments are used for the wood fragments of the reinforcing layer, and the fine wood fragments are used for the wood fragments of the soft layer. In the manufacturing method according to claim 3 or claim 4,
The method according to claim 1, wherein the woody soil formation step further includes a reforming step in which the wood pieces are treated with a solution containing ammonium iron citrate. In the manufacturing method according to claim 3 or claim 4,
The method according to claim 1, wherein the woody soil formation step further includes a reforming step in which the wood pieces are treated with a solution containing ammonium iron citrate and iron sulfate. In the manufacturing method according to any one of claims 3 to 6,
The manufacturing method whose shaping | molding of the said formation process is performed by the high frequency press.