JPH044825A - Formed medium for plant cultivation and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title medium with fiber-laminated planes stacked vertically and its upper surface with numerous irregular ripple-type flex planes, through such processes that a number of binder-contg. inorganic fiber mats are mutually laminated, the resulting laminate is compressed with its thickness constant, and the binder is then cured in a thermosetting oven and the resulting laminate is cut into slices. CONSTITUTION:A number of binder-contg. inorganic fiber mats are mutually laminated, the resulting laminate is compressed in parallel with the lamination plane with its thickness constant, and the binder is cured in a thermosetting oven and the resulting laminate is cut at a specified length into blocks. Each of the blocks is then cut in the direction same as that for the compression into slices, thus obtaining the objective medium good in the water- and air- permeability, plant root penetrability etc. in the thickness direction and excellent in the shape retainability in both the front and back directions, non-shrinkability etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molded medium used for raising paddy rice seedlings, vegetables, and plants.

[Conventional technology]

Conventionally, paddy rice seedlings for mechanical rice transplantation were grown in seedling boxes (inner dimensions: 58 cm).
m x 28 cm x 3 am), use commercially available soil-based or non-soil-based materials, or soil sterilized by the farmer with fertilizer added and pH adjusted as a seed bed, sow the seeds, cover with soil, and raise seedlings. are doing. As the soil for this covering,
Regardless of whether the seed bed is soil-based or non-soil-based, in the case of commercially available materials, the entire amount of required fertilizer is usually supplied from the seed bed without adding fertilizer. Many non-soil-based materials generally have poorer fertilizer retention ability than soil-based materials.

Recently, as a type of non-soil-based material, inorganic fiber molded medium, which is made by adding fertilizer to inorganic fibers such as rock wool and molding it into a mat shape to match the shape of the seedling box, has been developed because it is lightweight and easy to handle. It is used.

Early molded media were cut in the fiber direction or horizontal direction and used, which caused problems with root elongation.

In order to improve this point, the mat-shaped molded medium, which has been layered horizontally, was cut vertically, turned into a 90" shape, and then used by gluing the sides with adhesive. This molded medium Most of the constituent fibers are oriented in the thickness direction, which is preferable in terms of water permeability, pressure resistance, and shape retention. The dimensional stability of the seedlings is low, and when it absorbs water, it shrinks in the plane direction, creating voids inside the seedling box, causing problems such as seeds and soil falling into the voids, causing uneven seedling growth and uneven density. .

Therefore, for example, in Japanese Patent Publication No. 1-57930, a thin mineral fiber mat consisting of a single layer in which fibers are oriented and laminated in a plane is bent and folded into a continuous wave shape and partially adhered, and a thick aggregate is made of water. A mineral fiber seedling raising block has been proposed in which a mineral fiber mat for cultivation is cut into thin slices in the longitudinal direction to form a block, and the block is turned 90 degrees so that the cut surface of the block is the upper or lower surface and has a fiber orientation component in the vertical direction. ing. By using such a seedling growing block,
The company claims that it improves the compression resistance, water permeability, and air permeability in the thickness direction, as well as increases the dimensional stability in the plane direction, and solves problems such as shrinkage in the plane direction, which are the disadvantages of conventionally used mats.

[Problem to be solved by the invention]

In the above method, the mat that has been molded into a mat shape is further cut, the cut surface is turned into the upper surface or the lower surface, adhesive is applied to the side surface, and the two pieces are glued together to form a seedling box. The size of the seedling block is made of mineral fiber for assembly.

Since three to four steps are required after forming the mat into a mat, and there are joints, it is necessary to attach a lower layer to the mat in order to maintain its shape and make it easier to handle.

Further, when a mineral fiber mat is simply bent and folded into a continuous wave shape, a wave-like vertically oriented component is generated on the side surfaces, but at the same time, the folding direction is perpendicular to the front surface. Therefore, when this is cut into thin slices in the longitudinal direction, a wavy vertically oriented component is generated on the upper surface of the cut surface, and a horizontal fiber oriented component that is the same as the folding direction is generated on the side wall. As a result, the connectivity in the plane direction is strengthened, and when seedlings are vertically divided and scraped from the medium, the number of seedlings tends to be uneven, which tends to cause problems, making it unsuitable as a paddy rice seedling growing medium for mechanical rice transplantation.

The purpose of the present invention is to solve these problems and provide a molded culture medium that can be used as an integrated seedling growing mat for lees beds by simply cutting the mat.

[Means to solve the problem]

As a result of extensive research in order to solve the above-mentioned problems, the present inventors discovered that a multi-layer stack of thin inorganic fiber mat layers was laminated in a direction parallel to the laminated surface under a constant thickness condition. The present invention was completed after realizing that a thick plate-like body could be obtained by compressing the body.

That is, the present invention provides: (1) a molded medium for plant cultivation comprising mineral fibers,
A thick aggregate of laminated inorganic fiber thin layer mats that are bent and undulated in a large number of unsteady ripples are intertwined with each other inside and between each layer and partially adhered with a binder, and then cut into thin slices to form a large number of layers on the top surface. A molded medium for plant cultivation in which an irregular ripple-shaped curved surface appears and the fiber lamination surface is vertically oriented, (2) the bulk specific gravity of the thick aggregate is 20 to 250 kg/m
3, the molded medium for plant cultivation according to (1) above, whose dimensions when sliced correspond to the dimensions when closely stored in a seedling nursery box, and which is an integral product without sub-adhesion; (3) molded medium PH4.5-6 with acidifier without fertilizer
(4) A molded medium for plant cultivation according to (1) or (2) above, which is adjusted to the following: By compressing the inorganic fiber mat in a direction parallel to the fiber lamination surface under a constant thickness condition, the thin inorganic fiber mats are bent into a large number of unsteady ripples intertwined with each other and within each layer and between the layers. The resulting thick aggregate is passed through a thermosetting furnace to harden the binder, then cut to a predetermined length to form a block, and then the block is cut into thin slices lengthwise in the same direction as the compressing direction. A method for producing a molded medium for plant cultivation, characterized in that: (5) a thick aggregate or a thin inorganic fiber mat containing a binder in which fibers are oriented and laminated in a plane is placed on a conveyor substantially perpendicular to the direction of conveyance; The inorganic fiber mat that is transported while being continuously folded and stacked in the direction is compressed from above and below until it reaches a predetermined thickness, and while the thickness remains constant, the subsequent pair of upper and lower conveyors slow down the transfer speed to stack the fibers. The above (4
) is a method for producing a molded medium for growing plants.

This will be explained in detail below.

Mineral fibers used in the present invention include, for example, rock wool, glass wool, ceramic fibers, etc. In particular, blast furnace slag by-produced from blast furnaces in steel plants and/or natural stones such as basalt and diabase are used in cupola, electric Rock wool (also referred to as rock wool, slag wool, or mineral wool) that is melted in a furnace or the like and blown into fibers by centrifugal force and/or fluid pressure such as air or steam can be preferably used.

These fiberized inorganic fibers are usually collected in a suspended state on a conveyor together with a sprayed polymer binder, but at this point they are collected in a low-density layer to form a fiber aggregate. The fibers are then compressed to a required thickness in a curing furnace, the polymeric binder is hardened, and the fibers are partially adhered to each other, forming a material for a molding medium.

Examples of the polymer binder as a binder include:
Thermosetting resins such as phenol resins, melamine resins, and urea resins, and thermoplastic resins such as acrylic resins and vinyl acetate resins are preferred.

The fiber direction of the inorganic molding medium produced in this way is generally layered in the horizontal direction, which means that it is in the same direction as the traveling direction of the layered fiber aggregate or perpendicular to the traveling direction. This shows that most of the fibers are oriented in the direction, and there are almost no fibers in the direction perpendicular to the horizontal direction.

In the molded culture medium for plant cultivation of the present invention, the thin mat of inorganic fibers is bent and undulated in an unsteady ripple pattern, and each mat is intertwined with each other inside and between the layers and partially adhered with a binder. This is a molded culture medium for plant cultivation in which a thick layered aggregate is cut into thin slices to reveal a large number of unsteady ripple-shaped curved surfaces on the upper surface, and the fiber laminated surfaces are oriented in the vertical direction. The bulk specific gravity of the above aggregate is 20-2
This is a molded culture medium for plant cultivation that weighs 50 kg/m3, has dimensions when cut into thin slices that correspond to dimensions that are closely stored in a seedling nursery box, and is an integral piece without any adhesive.

A specific method for producing the molded culture medium of the present invention is to laminate two or more layers of thin inorganic fiber mats in which the fibers are oriented and laminated in a plane as described above, and to By compressing the fibers, a thick fiber aggregate with a smooth surface and an undulating thickness is formed in which the inner inorganic fiber thin layer mats are bent into a large number of unsteady ripples inside each layer and between the layers. This aggregate is passed through a thermosetting furnace to harden the binder and then cut to a predetermined length to form a block.The block is cut into thin slices lengthwise in the same direction as the compressed direction to create ripples in the block. It is characterized in that it is used with the cut surface where the mold bending surface is exposed as the top or bottom surface and the laminated surface is oriented in the vertical direction.
The method for laminating thin inorganic fiber mat layers of more than one layer is carried out by continuously or discontinuously stacking multiple thin inorganic fiber mat layers collected in the conventional cotton collection process, and this method In this case, it is possible to obtain a plate-shaped body that is considerably thicker than conventional products.

Discontinuous stacking methods include stacking thin mats that have been cut to a predetermined length in the longitudinal direction flatly to form a thick long plate, or uncutting them and hanging them back and forth from the vertical direction to create a uniform width. Fold and stack.

As a method for continuously laminating the layers, they can be laminated as appropriate on a transfer conveyor. For example, as in the invention described in British Patent No. 733,924 and US Pat. No. 2,503,067, a long thin-layer mat made of uncured binder-adhered fibers orientated and laminated in a plane at right angles to the transport direction of a conveyor. Multiple layers can be stacked by transporting on a conveyor while folding and hanging back and forth in the direction of.

In this case, when folding, the laminated portion of the thin layer mat is shifted by the amount transferred, or the entire layer is continuously laminated in a uniform state on the conveyor, which is most preferable.

FIG. 5 shows a thin layered mat 1 of inorganic fibers being reciprocally suspended over a transfer conveyor 2 in a direction substantially perpendicular to the transfer direction to form a thick layered mat 3 folded into multiple layers. , is an elevational view showing the compression in the vertical thickness direction by the upper compression conveyor 4 and the transfer conveyor 2.

FIG. 6 is an enlarged perspective view of the thick mat 3 that has been continuously folded into multiple layers in this manner.

The thick elongated laminate plate thus obtained is compressed in a direction parallel to the laminate surface while maintaining a constant thickness. When compressing, a discontinuous method may be used in which the material is cut to a predetermined length, the top and bottom are fixed, and pressing force is applied from the left and right sides, but a continuous method that changes the speed ratio between the two pairs of conveyors is more effective. .

In other words, the material is compressed to a constant thickness by a pair of upper and lower conveyors and transferred at a constant speed, and then continuously supplied between a pair of upper and lower low-speed conveyors that are installed in a plane continuous with the transfer direction. When moving from a high-speed transfer state to a low-speed transfer state, the excess supply is forced into the laminated mat and the inorganic fiber thin layer mats are compressed and entangled with each other within each layer and between the layers, resulting in a large number of unsteady conditions. Since a long elongated plate-like body that is bent and undulated in a ripple pattern is formed, the binder can be cured by passing it through a thermosetting oven as it is.

1-4 show embodiments of the present invention.

First, the thick-layered plate-like body shown in Fig. 2 can be obtained by cutting thin-layered mats and stacking them in large numbers, or by bending and folding thin-layered mats into multi-layered layers by hanging back and forth in the longitudinal direction a strip of thin-layered mats on a flat surface. This is a compressed image from the left and right directions of the figure.

Next, this thick long plate-like body was cut to match the length when used as a molded medium, and further cut to the same size as the width when used as a molded medium to form a block. The block is laid in a seedling box with its orientation changed by 90'' so that the surface with a large number of uneven ripple-shaped curved surfaces faces either the top or the bottom.

Further, FIG. 4 shows the thick-layer long mat 3 of FIG. 6 obtained by folding and stacking long thin-layer mats on a transport conveyor in a direction substantially perpendicular to the transport direction, and transporting the thick-layer long mats 3 to the upper and lower stages of the latter stage. This figure shows a thick laminate plate-like block whose fiber direction is bent in a discontinuous and unsteady ripple pattern by continuously compressing it in the above-mentioned transport direction by slowing down the speed of a pair of conveyors.

This multi-rippling plate-shaped body means that there are many non-uniform corrugations on the sides of the plate-shaped body in the transport direction, and by doing this, it is possible to Not only the horizontal direction of the molding medium, but also the presence of fiber components in the vertical, horizontal, and diagonal directions.

As shown in Fig. 4, this plate-like body has a surface with many uneven ripple-shaped curved surfaces on the side surface A, and a large number of uneven ripple-shaped curved surfaces on the upper and lower surfaces B. In order to do this, the plates appear aligned in a direction perpendicular to the traveling direction of the plate-like bodies, and on the front surface C, the folded and laminated state of the thin mats appears arranged in the horizontal direction.

The forming medium for paddy rice seedlings of the present invention has a bulk specific gravity of thick aggregates of 2.
0 to 250 kg/m', particularly preferably 50 to 1.00
kg/m3, and can be made into a plate-like body made of a one-piece piece without any lower adhesives and sized to be closely stored in a seedling nursery box when cut into thin slices. As shown in Figures 1 and 3, the A side has a vertical fiber orientation with many unsteady rippling bends and undulations, while the 8th and 0th sides have a vertical fiber orientation. There are many fiber orientations that match the folding direction of the vertical thin mat.

The fibers of this block are bonded to each other by a sprayed adhesive, and the fibers are oriented parallel to the sides, so when used as a forming medium for growing rice seedlings,
It can maintain water permeability, pressure resistance, and air permeability in the thickness direction, and has a ripple-shaped, undulating structure in the horizontal direction, which prevents cracks and collapse. It has high dimensional stability and does not shrink horizontally even when it absorbs water. In the present invention, the laminated surfaces are oriented in the vertical direction, and especially in the case of Fig. 3, the vertical direction corresponds to the folding direction of the thin layer mat, so when used as a mat for raising rice seedlings, the raised seedlings are removed from the medium. It is easy to divide the thin mat into blocks in the vertical direction, and there is no problem during mechanical rice transplantation.
Most preferred.

In this way, the molded medium of the present invention has high horizontal dimensional stability, but unlike a thin mat simply bent and folded into a continuous wave pattern, the fibers are bent into a discontinuous and unsteady ripple pattern. This has the advantage that fibers do not extend long in the width direction of the medium, making it easy to separate and scrape seedlings with a rice transplanter.

The volume specific gravity of the fiber aggregate thus made is 20 to 250k.
g/m' is preferable, more preferably 50 to 100 kg
/m3.

If the weight is less than 20 kg/m 3 , the compressive strength and bending strength will be low, resulting in poor handling properties, and if it exceeds 250 kg/m 3 , it will become too hard and have a negative effect on the elongation of plant roots.

The molding medium for growing paddy rice seedlings of the present invention has a size that allows it to be closely accommodated in a seedling box for growing paddy rice seedlings as it is.

This molding medium may be adjusted to pH 4 with an acidifying agent if necessary.
．． It can be adjusted to 5 to 6, and fertilizers, hydrophilic agents, water retention agents, etc. can be added. As the acidifying agent, known mineral acids or salts thereof, organic acids, and acid salts of condensed phosphoric acid can be used. Examples of mineral acids include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. In addition, as salts of mineral acids,
Examples include iron sulfate, sodium sulfate, manganese sulfate, ammonium sulfate, and potassium acid phosphate. Examples of organic acids include citric acid, fumaric acid, malic acid, and nitrofumic acid. In addition, when nitrofumic acid or its salt, such as ammonium nitrofumate, is used in combination with the above acid or its salt, seedling raising or cultivation results will be even better.

Among the above acidifying agents, solid acidifying agents include, for example, iron sulfate, lime superphosphate, potassium acid phosphate and other acidic mineral acid salts, ammonium salts of mineral acids such as ammonium sulfate and ammonium nitrate, and citric acid. acids, fumaric acid, malic acid, and other organic acids, or acidic salts of these organic acids, and ammonium salts of these organic acids, etc., in powder, granule, granule, lump, and other arbitrary shapes. Examples include various solid acidifying agents such as molded articles. The mineral acid salts mentioned above, such as lime superphosphate, potassium acid phosphate, ammonium sulfate, ammonium nitrate, and ammonium chloride, act both as acidifying agents and as fertilizers.

The same applies to ammonium salts of organic acids, acidic potassium salts, acidic lime salts, and the like.

The acidification treatment with these acidifying agents may be performed during or after the manufacturing process of the molded medium, and can be added by conventional methods such as spraying, coating, and impregnation.

When the acidifying agent is in solid or powder form, it may be used as an aqueous solution, or it may be dissolved by water sprinkling added later. In the latter case, water sprinkling gradually acidifies the area and the effect is long-lasting.

Examples of fertilizers include nitrogen fertilizers such as ammonium sulfate, ammonium chloride, ammonium nitrate, and urea, potassium fertilizers such as potassium sulfate and potassium chloride, and phosphoric acid fertilizers such as lime superphosphate and ammonium phosphate.

In addition, natural fertilizers such as bone meal, fish meal, fermentation extract, etc. may be added. These fertilizers may be single or compound fertilizers. The amount of fertilizer to be added is appropriately determined depending on the use of the molding medium, or when used for raising paddy rice seedlings, it is preferable to use it without fertilizer.

Examples of the hydrophilicity imparting agent include alkyl polyoxyethylene ether, alkylphenyl polyoxyethylene ether, alkyl carbonyloxy polyethylene, N,
Nonionic surfactants such as N-di(polyoxyethylene)alkanamide, fatty acid polyhydric alcohol ester, fatty acid polyhydric alcohol polyoxyethylene ether, fatty acid sucrose ester, fatty acid monoglyceride, N,N-di(alkanol)alkanamide, etc. polyvalent agents such as ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1゜3-butanediol, 1,4-butanediol, glycerin, butanetriol, polyethylene glycol, polypropylene glycol, dicrycerin, etc. Alcohol may be mentioned.

The amount of these hydrophilicity imparting agents used is 0.05 to 2 wt%, preferably 0.1 to 0.0% based on the granulated inorganic fiber base material.
．． 5 wt% is appropriate.

[For production]

As described above, the forming medium for growing paddy rice seedlings of the present invention has a cross section in which at least two or more thin inorganic fiber layers are laminated in the plane direction, and each fiber is bent in an independent ripple pattern, making it inert. Because it is oriented in multiple regular directions, and each fiber is formed parallel to the vertical direction, it has good water permeability in the thickness direction, air permeability, compression resistance, and penetration by plant roots. In addition to being oriented in multiple directions in the horizontal direction, it is entangled or bent, so it has particularly high connectivity in the vertical and horizontal directions, and has shape retention in the front and rear directions, non-shrinkage, etc. It has desirable performance.

In addition, since the fiber direction is discontinuous and ripple-shaped, the fibers do not extend long in the width direction of the medium, making it easy to divide and scrape seedlings with a rice transplanter, etc. while maintaining the above-mentioned shape retention. .

〔Example〕

Hereinafter, specific examples of the present invention will be described.

Inorganic fiber raw materials are melted and made into fibers in a normal electric furnace, etc., and approximately 2% by weight of phenolic resin is sprayed onto the suspended fibers using centrifugal force or gas blowing to form a thin fiber layer of approximately 16 fins. The plate-shaped body, which is made by laminating about 60 thin fiber layers and has a thickness of about 1000 mm and a density of 18 kg/m3, is sequentially compressed to a predetermined thickness, and then transported while maintaining a constant thickness and compressed from the longitudinal direction. By doing this, a plate-like body with a smooth surface and many wavy inner fibers is formed, and then 2
Dry with hot air at 50℃ to a thickness of 280 mm and a width of 600 m1.
It was made into a plate-like body with a density of 60 kg/m3.

This plate-like body is first cut into blocks with a length of 580 mm, and then a width of 18 mm is cut in a direction parallel to the direction in which the blocks are transported.
Cut into mm, thickness 18m, width 280mm, length 58
A forming medium for raising rice seedlings of 0Wl+I was obtained.

When the culture medium was placed in a seedling growing box with an internal size of 280 x 580 and sufficiently watered, it hardly contracted in the horizontal direction and no voids were formed between the medium and the wall of the seedling growing box.

Next, when the germinated paddy rice seeds were sown and covered with soil containing fertilizer (approximately 5 millimeters thick), the seeds fell into the gaps.
The work could be done smoothly without uneven seeding and soil covering.

Moreover, as a result of growing seedlings for 30 days, good-growing seedlings were obtained using the product of the present invention without causing the seedling density to become too dense or the seedlings to grow unevenly.

When this paddy rice seedling raising box was placed on a rice transplanter and seeds were sown, the seedlings could be easily removed using nails and a uniform number of seedlings was obtained.

〔Effect of the invention〕

The present invention provides a molded medium for plant cultivation made of mineral #A fibers, in which the fiber directions of each inorganic fiber are oriented in multiple irregular directions in the horizontal direction of the medium, but in the vertical direction. Because it has a large amount of fiber, it maintains good water permeability, air permeability, compression resistance, and penetration of plant roots in the thickness direction, and since the wiring runs in multiple directions horizontally, it does not get tangled or folded. Because of this, it has high connectivity in both the vertical and lateral directions, and has favorable performance such as shape retention and non-shrinkability in the front and back directions. Furthermore, the culture medium of the present invention does not require adhesive on the sides in the width direction, and is easy to handle because it is a single piece that is laminated in multiple layers for the width of the seedling box floor. A molding medium for growing rice seedlings that does not require a wafer is obtained, and since the fiber direction is perpendicular, there is no problem in dividing and scraping the seedlings with the claws of the rice transplanter, and the workability of the rice transplanter can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an example of a molded culture medium for plant cultivation of the present invention, and FIG. 2 is a perspective view of an inorganic fiber plate-like body used to obtain the product of the example. FIG. 3 is a perspective view of an example of a molded culture medium for plant cultivation made from a multi-layered mat formed by continuously reciprocating a thin-layered mat in a direction substantially perpendicular to the conveying direction of a conveyor. FIG. 4 is a perspective view of the multi-tiered laminated block before the culture medium shown in FIG. 3 is created. FIG. 5 is an elevational view of an apparatus for producing a multi-layered mat by continuously reciprocating and suspending thin-layer mats in a direction perpendicular to the conveying direction of a conveyor. FIG. 6 is an enlarged perspective view of a multi-layered mat made with the apparatus shown in FIG. 5. A: Surface corresponding to the surface of the medium where the ripple-like orientation of fibers appears. B: The surface of the plate has wrinkles almost parallel to the upper and lower surfaces (the surface of the plate has wrinkles almost parallel to the upper and lower surfaces) because the plate was compressed in the front-rear direction while applying pressure from the upper and lower surfaces, and the internal fibers were oriented in a ripple pattern. side). C: Side surface of a medium with fibers oriented in the vertical direction (side surface of a plate-like body with fibers oriented in the horizontal direction). 1... Thin layer mat, 2... Transfer conveyor, 3...
Continuous multi-layer laminated mat, 4...Upper conveyor that provides compression in the thickness direction. Figure 1 Figure 2 Figure 2

Claims (5)

[Claims] (1) A molded medium for plant cultivation consisting of mineral fibers,
A thick aggregate of laminated inorganic fiber thin layer mats that are bent and undulated in a large number of unsteady ripples are intertwined with each other inside and between each layer and partially adhered with a binder, and then cut into thin slices to form a large number of layers on the top surface. A molded culture medium for plant cultivation in which an unsteady ripple-shaped curved surface appears and the fiber laminated surface is oriented in the vertical direction. (2) The bulk specific gravity of the thick aggregate is 20 to 250 kg/m^3, the size when cut into thin pieces matches the size to be closely stored in the seedling nursery box, and it is a one-piece product without lower adhesives. The molded medium for plant cultivation according to claim 1. (3) The molded medium for plant cultivation according to claim 1 or 2, wherein the molded medium is fertilizer-free and whose pH is adjusted to 4.5 to 6 with an acidifying agent. (4) By laminating a large number of thin binder-containing inorganic fiber mats in which the fibers are oriented and laminated in a plane, and compressing the laminated inorganic fiber mats in a direction parallel to the fiber lamination surface under a constant thickness condition, The thick aggregate obtained by bending the inorganic fiber thin layer mats into a large number of unsteady ripples in which they are intertwined with each other within each layer and between the layers is passed through a thermosetting oven to harden the binder, and then cut into a predetermined length. 1. A method for producing a molded medium for plant cultivation, which comprises cutting the medium into blocks, and then cutting the blocks into thin slices lengthwise in the same direction as the direction in which the blocks are compressed. (5) A thick aggregate is an inorganic material in which a thin binder-containing inorganic fiber mat in which the fibers are oriented and laminated in a plane is conveyed by continuously folding and laminating the mat in a direction substantially perpendicular to the direction of conveyance. It is obtained by compressing a fiber mat from above and below until it reaches a predetermined thickness, then slowing down the conveyor speed of the following pair of upper and lower conveyors while keeping the thickness constant, and compressing it in a direction parallel to the fiber lamination surface. Claim 4
A method for producing the molded medium for plant cultivation described above.