JP2003333940A - Light-reflecting mulching sheet and method for using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an environmentally friendly lightweight mulching sheet having excellent light-reflecting properties and weed-proof functions, improving quality of cultivated products during cultivation of vegetables, flowers, fruit trees, etc., with a low load on operators and suitable for agriculture, etc. <P>SOLUTION: The light-reflecting mulching sheet is provided with a light- reflecting resin layer in at least a part of the surface of a filament nonwoven fabric having 2-25 μm filament diameter and 20-100 g/m<SP>2</SP>weight and has ≥50% light reflectance. A method for using the light-reflecting mulching sheet comprises laying the mulching sheet having the light-reflecting properties on the roots of the cultivated plants and allowing weeds grown in the ground surface part covered with the mulching sheet to stand without substantially removing the weeds. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mulch sheet suitable for use in fields such as agriculture, livestock, and forestry, and a method of using the same. More specifically, it is a composite sheet that has a light-reflecting resin layer on the surface of long-fiber non-woven fabric, is lightweight and easy to handle, and can significantly reduce the use of pesticides and reduce the amount of additional fertilizer and labor. It is a sheet. It is also a sheet that can be used to prevent the drainage of dissolved matter due to rainwater when the livestock excrement is temporarily stored outdoors.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 6-327361 discloses a soil coating material using a porous film, which is applicable to increasing the sugar content of edible fruit trees, premature ripening, and sharpening of coloring.

The polyolefin-based flash-spun non-woven fabric is excellent in moisture permeability, waterproofness, mechanical properties and chemical properties, and is used as a multi-sheet for mandarin oranges and the like. However, the flash spun non-woven fabric is paper-like and has a problem in that the sheet flaps due to the wind and a sound is generated. Further, since the surface is very smooth, if mud or water adheres to the sheet, there is a problem that it tends to slip when walking on the sheet. As a countermeasure, a sheet softened by embossing or the like is also on the market, but there is a problem that durability is lowered.

Further, in these multi-sheets, grass grows on the lower side of the sheet, and the sheet is lifted by the grass, which makes it difficult to increase the sugar content of the edible fruit tree and quickly ripen it by controlling the water content. There was a case. As measures against this, measures have been taken such as cutting weeds before laying multi-sheets and then spraying a herbicide, but it is very time-consuming and there is a problem that the burden on the aging farmer is large. Further, the use of pesticides such as herbicides poses a problem of environmental pollution, and it is desirable to suppress the use thereof as much as possible.

[0005]

DISCLOSURE OF THE INVENTION The present invention is lightweight, has excellent light-reflecting properties and has a weed-preventing function, and further improves the quality of cultivated products when cultivating vegetables, flowers, fruit trees, etc. Is small, and provides a multi-seat suitable for environment-friendly agricultural use and a method for using the same.
Furthermore, when growing plants such as vegetables and flowers in the summer season from July to August, we will try to provide a growing method that prevents damage to the roots due to rising soil temperature and enables early harvest of autumn vegetables. To do.

[0006]

[Means for Solving the Problems] Solving such problems
Therefore, the present invention takes the following means. That is, the first
Akira has a fiber diameter of 2 to 25 μm and a basis weight of 20 to 100 g /
m ²Light reflection on at least part of the surface of the long-fiber non-woven fabric
Has a resin layer with a light-transmitting property and has a light reflectance of 50% or more.
It is a characteristic light-reflective multi-sheet.

A second invention is the light-reflective multi-sheet according to the first invention, which has a light blocking rate of 95% or more.

Further, a third invention is characterized in that the long fiber non-woven fabric contains any one of carbon black, talc, titanium oxide or calcium carbonate, and the light-reflective mulch according to the first or second invention. It is a sheet.

Further, in the fourth invention, the water vapor permeability is 200 to 1
0000g / m ² · 24 hours, water pressure resistance 150-200
It is 00 mmAq, It is the light reflective multi-sheet in any one of the 1st-3rd invention characterized by the above-mentioned.

In a fifth aspect of the invention, the light-reflecting multi-sheet according to any one of the second to fourth aspects of the invention is laid at the root of a cultivated plant and grown on the ground portion covered with the multi-sheet. A method of using a light-reflective multi-sheet characterized by leaving the weeds without substantially removing them.

A sixth aspect of the invention is to provide at least a part of the ground under the multi-seat of any of the first to fourth aspects of the invention.
It is a method of using the light-reflective multi-sheet according to the fifth invention, characterized in that a hydrophilic fiber assembly containing plant fibers or acrylic fibers is laid.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION
It is necessary to have a light-reflecting resin layer of white or silver color on at least a part of the surface of the long fiber non-woven fabric having a fiber diameter of 2 to 25 μm.

The long fiber non-woven fabric used in the present invention is not particularly limited as long as it is a non-woven fabric produced by a spunbond method, a tow opening method, a flash spinning method or the like and having substantially no fiber cut ends. . Since the long fiber nonwoven fabric has excellent strength characteristics, it is possible to realize high durability during use. Material is polyester or polyolefin,
Almost any material can be used as long as it is made of a resin such as polyamide made durable by using a suitable weathering agent.

The main fibers constituting the long-fiber nonwoven fabric in the present invention have a fiber diameter of 2 to 25 μm. Fiber diameter is 2 μm
If it is smaller, the weather resistance will be remarkably reduced, and it will not be possible to continuously use it for 2 to 5 years, which is a problem.
If it exceeds 5 μm, the amount of fibers in the non-woven fabric is reduced, and it tends to be difficult to realize light reflection or shielding. Further, when laminated with a film or the like, the contact area is reduced, and the problem of peeling is likely to occur.

It is desirable that the long-fiber nonwoven fabric contains an appropriate amount of an ultraviolet stabilizer or an ultraviolet absorber. At least a part of the surface of the long-fiber non-woven fabric is provided with a light-reflecting resin layer such as white or silver in order to prevent heat from being transmitted to the ground by reflecting light. It may be provided on the entire surface or may be provided partially such as dots or lines.

The light reflectance in the present invention is required to be 50% or more, preferably 60% or more, and particularly preferably 70% or more. By increasing the light reflectance, it is possible to prevent the soil temperature from rising and to reduce the damage to the roots due to the rising temperature when growing vegetables and flowers in the summer months of July to August. In summer, the light is strongly reflected, so if the reflectance is too high, it may hurt the skin and eyes. Therefore, it is preferably 90% or less, particularly preferably 80%.
It has been found that ~ 85% or less is good.

The method of providing a light-reflecting resin layer of white or silver color on at least a part of the surface of the long fiber non-woven fabric is not particularly limited, but for example, a resin film is extruded and laminated, or laminated with an adhesive, or a resin. There is a method of coating. The resin is preferably a material having high light resistance, and for example, an acrylic resin is preferably used. Further, there is a means of kneading a material having light reflectivity into the fiber itself. Further, a method of applying a metal thin film such as aluminum or stainless steel to the fiber or the film surface by means such as vapor deposition, sputtering or plating may be used.

In order to obtain high light reflectivity, a method in which talc, calcium carbonate, titanium oxide, etc. are contained in a resin for lamination, coating, or kneading into fibers is also a preferred embodiment. It is one.

Further, the multi-sheet of the present invention preferably has a light blocking rate of 95% or more. When the shading rate is 95% or more, it becomes possible to exhibit an excellent weed-preventing function. It is preferably at least 98%, particularly preferably at least 99%. The following means are available as means for setting the light blocking rate to a desired value. One of them is a method of absorbing light by adding a pigment such as carbon to the raw material resin of the long fiber non-woven fabric or the moisture permeable and waterproof film. As another means, there is a method in which a metal such as SUS or aluminum is vapor-deposited or sputtered on either the nonwoven fabric or the moisture-permeable waterproof film. If the film itself does not have moisture permeability, the light-shielding rate does not change significantly even if minute holes are formed after the treatment such as vapor deposition. In the present invention, even if the light-shielding rate is not 100%, it is waterproof, so that weed plants can be stressed due to lack of water, and a weed-preventing effect is exhibited.

The basis weight of the multi-sheet of the present invention is 20 to 1
It is 00 g / m ² , and preferably 45 to 80 g / m ² . 45 to maintain proper mechanical properties and durability
It is preferably g / m ² or more, and 100 g in consideration of workability such as labor in laying under hot weather or slope work.
The result of the field test revealed that it is preferably / m ² or less.

In the multi-sheet of the present invention, the long-fiber nonwoven fabric and the moisture-permeable waterproof membrane may be bonded together with an adhesive. The moisture-permeable and waterproof membrane used by being bonded to the long-fiber nonwoven fabric in the present invention may be a porous film or a non-porous film. As the porous film, olefin type film, polyester type film, fluorine type film, etc. which are directly perforated by laser etc., polymer in which calcium carbonate particles are kneaded is extruded on a flat surface and then stretched to generate voids. Although it can be used, it is not particularly limited. In the case of a non-porous film, the material itself such as urethane or polyester elastomer needs to have moisture permeability, and the resin composition is selected according to the required moisture permeability.

In the present invention, the film thickness of the resin layer is preferably in the range of 7 to 50 μm in order to achieve an appropriate water vapor transmission rate in a non-porous film state. When the film thickness is thicker than 50 μm, the water pressure resistance can be increased, but the problem of poor moisture permeability tends to occur. On the other hand, if the film thickness is less than 7 μm, the film will be broken when water pressure is applied, making it difficult to obtain a high water pressure resistance. Further, if the film is too thin, there is a problem that the film is likely to be broken during handling or during use.

In the present invention, when a non-porous film is used, it is preferable to use a block copolymerized polyester composed of a hard segment and a soft segment.
The polyester has a melting point of 150 to 180 ° C. and a melt flow rate (MFR) of 230 to 30 g.
/ 10 minutes is preferable. The melting point of the block-copolymerized polyester is determined by the structure and the composition ratio of the soft segment, but within the range of the inventors' investigation, it must be within this temperature range to set the water pressure resistance and moisture permeability to desired values. Was preferred.

Also, the MFR at 230 ° C. is 30 to 150 g.
/ 10 minutes is preferable in order to reduce fluctuations in the thickness and width of the film. It is particularly preferable to process the copolyester used in the present invention at around 230 ° C. from the viewpoint of film processability. If the MFR is higher than 150 g / 10 min, the edges tend to be wavy due to the influence of surging, etc., and the fluctuation in width tends to be large, and if the MFR is too low than 30 g / 10 min, the film is made thin for the purpose of the invention. It tends to be difficult to mold.

From the viewpoint of adhesiveness, it is particularly preferable that a polyester-based long-fiber nonwoven fabric, which is a similar material, is joined as a reinforcing material to the block copolymerized polyester film in the present invention. When the membrane and the long fiber non-woven fabric are bonded by extrusion lamination, the fiber diameter of the long fiber non-woven fabric is 3 to
It is preferably 20 microns, particularly preferably 5
~ 16 microns. By making the fiber diameter thin, it becomes possible to prevent the membrane from breaking. According to the experience of the inventor, when the thickness of the film is less than ½ of the average fiber diameter, there is a tendency that the film tends to be broken or peeled from the fiber layer. On the other hand, when the fiber diameter is smaller than 3 μm, the problem that the reinforcing effect becomes small tends to occur. Although the fiber diameter is considered to be an average value as a representative value, in order to obtain bulkiness and stretchability, even if fibers having a thickness larger than the average value are mixed up to about 30% by weight, the object of the present invention is not so much. Do not block. Therefore, the average fiber diameter may be calculated by taking out only 70% of the whole fibers from the thinner one.

The polyester resin which is the material for the long fiber nonwoven fabric in the present invention is polyethylene terephthalate,
The resin is a homopolymer selected from the group consisting of poly (trimethylene terephthalate) and polybutylene terephthalate, or a copolymer or blend in which any of these groups is present in a part of the repeating unit. As a result of studies by the present inventors, the polyester-based non-woven fabric in the present invention has good adhesiveness with the copolymerized polyester film, and is particularly not required to undergo special surface treatment before bonding to improve the adhesiveness. preferable. With polyolefin-based non-woven fabrics,
The adhesiveness was poor and peeling occurred during use, which was not preferable.

The polyester non-woven fabric can be further improved in adhesiveness by subjecting it to corona treatment or the like as required, and is recommended. It is also possible to mix an appropriate antioxidant, weathering agent, lubricant, colorant or the like with the polyester non-woven fabric. Especially in the case of direct sunlight exposure such as house wrap application, the total amount of the ultraviolet absorber, the ultraviolet stabilizer and the antioxidant is 0.1 to 15% in order to prevent the deterioration due to ultraviolet rays and the like, preferably 0.1.
5 to 12%, particularly preferably about 3 to 10% is preferable.

The basis weight of the polyester non-woven fabric for extrusion lamination is preferably 5 to 50 g / m ² of the polyester non-woven fabric. When the fabric weight is too small, it is difficult to obtain a sufficient reinforcing effect, and when the fabric weight is too high, not only the thin and lightweight moisture-permeable waterproof sheet which is the object of the present invention does not become, but also the sheet becomes too hard and bones stand up when bent. When it occurs, the moisture-permeable membrane layer tends to be destroyed.

The long-fiber nonwoven fabric used in the present invention is heat-embossed and has a thickness of 0.05 to 0.
It is preferably 35 mm. Heat embossing can significantly improve the sheet strength. It is also one of the preferred embodiments to perform needle punching or hydroentanglement in order to increase the degree of fiber entanglement, but if the surface of the non-woven fabric is too fluffy, the adhesiveness to the membrane tends to deteriorate. Although it is possible to improve the fiber adhesiveness by using a binder such as a resin, it is necessary to consider the adhesiveness with the polyester copolymer. If the thickness of the sheet is too thick, the adhesion to the film will be poor, and if it is too thin, it will have a paper-like texture.

The characteristics of the moisture-permeable waterproof sheet according to the present invention
Has a water vapor transmission rate of 200 to 10,000 g / m²・ 24 o'clock
It is preferable that the water pressure resistance is 150 to 5000 mmAq
Good If the water vapor permeability is the above value, for example,
When used for the application, the humidity rises too much and causes dew condensation.
There is no problem of contact with the human body, such as clothing
Then, it is preferable because there is no problem of being hot and humid when worn. Transparent
Humidity is 10000g / m ²・ Not much even if it exceeds 24 hours
No problem, but durability, weather resistance, etc. tend to decrease.
Tend. Also, the water pressure resistance is 150 to 20000 mmA.
If it is q, water will not get inside even if rain etc. adheres to the surface of the sheet.
Never infiltrate. Water pressure resistance exceeds 5000 mmAq
Although there is no problem in terms of waterproofness, the moisture permeability decreases
In some cases, the water pressure resistance and moisture vapor transmission rate are appropriate depending on the usage conditions.
It is preferable to balance

In the extrusion laminating method of the present invention, a moisture-permeable resin is extruded from a T-die with a width substantially equal to that of the reinforced non-woven fabric to form a film-like film having a thickness of 5 to 30 cm.
There is a method in which the film is cooled at the same time as it is brought into contact with the reinforced non-woven fabric with an offset of approximately and then sandwiched by rollers to be bonded. Since the copolyester used in the present invention has high adhesiveness, the peelability from the roll may be deteriorated and the process passability may be deteriorated. Therefore, at least the roll brought into contact with the film is a resin having good releasability such as PTFE. Is preferably coated with or matted.

Further, the resin layer made of the multi-sheet block copolymerized polyester in the present invention is 100 to 1 for the purpose of stabilizing the crystal structure and improving elongation recovery.
It is also preferable to perform heat treatment at a temperature of 80 ° C. for about 1 to 30 minutes. This makes it possible to improve the elongation recovery and morphological stability of the film when subjected to tensile deformation and the like.

In the present invention, for the purpose of increasing the sugar content of edible fruit trees and vegetables and aging the fruit at an early stage, the multi-sheet having the weed-preventing function of the present invention is used from the time of flowering to one month before harvesting. It is laid at the root, but weeds that grow on the ground where the mulch sheet is laid need not be substantially removed. In the case of a multi-sheet that does not have weed control,
Since grass grows under the multi-seat and the sheet is lifted by the grass, it may be difficult to achieve effects such as increasing the sugar content of the edible fruit tree and premature aging by controlling the water content. Although measures have been taken such as cutting the weeds before laying the sheet and further spraying the herbicide, it takes a lot of time and labor, and there is a problem that the burden on the aging farmer is large. Also, the use of pesticides such as herbicides has the problem of environmental pollution,
It is necessary to suppress its use as much as possible. On the other hand, since the mulch sheet of the present invention has a weed-preventing function, the use of pesticides such as herbicides is considerably suppressed. Moreover, since the dead grass decays into a nutrient, there is an advantage that the need for additional fertilization is low.

The laying time of the mulch sheet is preferably from after flowering to one month before harvesting. If the flowering period is before the flowering, the flowering condition may not be good. Further, after one month before harvesting, it becomes difficult to apply appropriate stress to the plant, and the coloring of the fruit is slightly improved, but it is not possible to obtain sufficient time for improving the sugar content. A plant such as a weed that has died by laying a multi-sheet can be used as a hydrophilic fiber aggregate as a water retainer described later. Further, since the multi-sheet of the present invention has a high light reflectance, it can exhibit a pest repellent effect after flowering, and positive use of this effect is also a preferred embodiment.

The multi-sheet is preferably removed after harvesting crops such as fruits and vegetables, and the ground is exposed directly to the air. By adding air, it becomes possible to activate the ground, and it is possible to improve the growth of plants from the next year onward. When the multi-sheet of the present invention is used, even if the temperature rises in spring and the environment where weeds are likely to grow, the time when weeds start to grow is delayed by about 1 month, and the problem of weeding is small. Was also found.

It is preferable to lay at least part of a hydrophilic fiber assembly containing plant fibers or acrylic fibers on the ground under the multi-sheet of the present invention. These hydrophilic fibers are capable of retaining water, and when the lack of water is severe, such as when rainfall is continuously low over a long period of time, the plant can be treated without special treatment such as irrigation. It becomes easy to retain the minimum amount of water necessary to maintain the life of the person. Further, in the case of plant fiber, it can be decomposed with time and used as a plant fertilizer, which is particularly preferable. Although plant fibers have some effect even on weeds that have died due to mulch sheet, it is preferable to additionally place fiber aggregates such as jute, hemp, cotton, kenaf, bamboo and rayon under the mulch sheet. In the case of an acrylic fiber, it is preferable to use a polymer modified by introducing a hydrophilic group such as a carboxylate group so as to enhance water retention, and examples thereof include Lanseal (manufactured by Toyobo Co., Ltd.) and Bell Oasis ( Kanebo Corporation) and the like.

With the mulch sheet, the shading rate and air permeability can be adjusted by laying so that the soil temperature at a depth of 10 cm from the ground surface is lowered by 3 ° C. or more in the summer season from July to August as compared to when it is not laid. preferable. During the day from July to August,
The temperature of the ground rises, and the temperature rises too much, causing the problem of root damage of fruit trees. However, when the multi-sheet of the present invention is used, the multi-sheet can be used even at the hottest time when the daytime temperature is 30 ° C. or higher. 3-7 compared to the case without
A decrease in ground temperature of about ℃ was confirmed, and no decrease in plant vigor was observed.

Further, the effect of suppressing the increase in soil temperature is great also for the growth of plants such as spinach grown at a relatively low temperature, and a large difference in the growth status of the plants was observed when the temperature was lowered by about 2 ° C. Examples of application of the multi-sheet of the present invention include vegetables such as cucumber, eggplant, and tomato, flowers such as haze grass, and the like.

[0039]

EXAMPLES The present invention will now be described with reference to specific examples, but the present invention is not limited thereto. The measuring method used in the present invention is as follows. (Water vapor transmission rate) [4.1.1 (A-
1 method) Calcium chloride was used, φ70 mm]. (Water pressure resistance) It was measured according to JIS L 1902 [5.1 B method (high water pressure method)].

(Fiber diameter) Photographs were taken with a scanning electron microscope at an appropriate magnification to randomly select 20 to 200 fibers.
The distance between the side surfaces of each fiber was measured by selecting the degree. The fiber diameter was measured by converting from the photographing magnification and assuming a circular cross section. The distribution of fiber diameter is generally in the form of a bell-shaped normal distribution. However, when fibers with different fiber diameters are mixed, there are multiple peaks.
Was selected and the average value was calculated.

Example 1 Perprene resin GP-550 manufactured by Toyobo Co., Ltd. (MFR34 at 230 ° C., melting point 174 ° C.)
Was extruded with a T-die at 230 ° C., and with a 15 cm offset, it was brought into contact with 20 g / m ² of polyester black spunbonded non-woven fabric (Equle 6401AD, average fiber diameter 14 μm) to an average thickness of 12 μm. It was pasted so that it would become. The obtained sheet has a water vapor transmission rate of 8400 g / m ^{2 for} 24 hours and a water pressure resistance of 150.
It showed a very excellent performance of 0 mmAq. The light reflectance of the multi-sheet was 64% and the light blocking rate was 98%. When used in a tomato field with the resin side up at the base of the vegetables, the growth was good. Two weeks after the use, the weeds were almost dead and the weed control effect was confirmed. It was found that there was no problem with the tree vigor in the production of the next year. During the daytime when the outside air temperature was 35 ° C, the temperature at a depth of 10 cm was measured and found to be 28 ° C, which confirmed the effect of preventing the rise in the ground temperature.

(Embodiment 2) Moisture-permeation and waterproof porous polyethylene
Tiren film and Toyobo Co., Ltd. polyester black spa
Bonded non-woven fabric (Equle 6401AD, average fiber diameter 1
4 micron) and acrylic adhesive
It was The obtained sheet has a water vapor transmission rate of 9100 g / m. ²・ 24
It showed excellent performance such as time and water pressure resistance of 5300 mmAq.
The light reflectance was 64% and the light blocking rate was 94%. Example 1
Fill the multi-sheet with the root of the vegetables in the tomato field as well as
When used with the side facing up, the growth condition is good.
It was Two weeks after use, weeds are almost dead and weed-proof
The fruit was confirmed. Even in the production of the next year
I knew there was no problem. Daytime when the outside air temperature is 35 ° C
The temperature of 10 cm deep on the ground was measured and found to be 28 ° C.
It was confirmed that the effect of preventing the rise in soil temperature was confirmed. Workability
There was no problem at all. After 2 weeks of use, weeds are almost
It has withered and its weed control effect was confirmed.

(Comparative Example 1) When nothing was laid on the roots of vegetables in a tomato field, the leaves were not healthy because the vegetables were wilted in the afternoon of a fine sunny day. During the daytime when the outside air temperature was 35 ° C., the temperature at a depth of 10 cm was measured and found to be 36 ° C., which was a problem because the roots in the ground were considerably dry.

[0044]

EFFECTS OF THE INVENTION According to the present invention, when vegetables and flowers are grown in the summer season from July to August, the root temperature is controlled to prevent root damage due to temperature rise, and early harvest of autumn vegetables can be achieved. to enable. Furthermore, the nonwoven multi-sheet of the present invention is lightweight and easy to handle, it is possible to significantly reduce the use of pesticides, reduce the amount of additional fertilization and the labor, and reduce the environmental load and labor burden, especially It is suitable as an agricultural multi-sheet.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2B024 DA01 DB03 DB07                 4F100 AA08A AA08H AA21A AA21H                       AA37A AA37H AC10A AC10H                       AK01B AK04 AK25 AK41                       BA02 CA13A CA23A DG04A                       DG15A DJ06 GB01 JA13A                       JD04 JD05 JN02 JN06B                       YY00A YY00B

Claims (6)

[Claims] 1. A fiber diameter of 2 to 25 μm and a basis weight of 20 to 1
A light-reflective multi-sheet having a light-reflecting resin layer on at least a part of the surface of the long fiber non-woven fabric of 00 g / m ² and having a light reflectance of 50% or more. 2. The light-reflective multi-sheet according to claim 1, which has a light-shielding rate of 95% or more. 3. The light-reflective multi-sheet according to claim 1, wherein the long fiber non-woven fabric contains any one of carbon black, talc, titanium oxide or calcium carbonate. 4. A moisture vapor transmission rate of 200 to 10,000 g / m ² ·
The light-reflecting multi-sheet according to any one of claims 1 to 3, which has a water pressure resistance of 150 to 20,000 mmAq for 24 hours. 5. The multi-sheet having light reflectivity according to claim 2 is laid at the root of a cultivated plant, and weeds growing on the ground portion covered with the multi-sheet are substantially removed. A method of using a light-reflective multi-sheet, which is characterized by leaving without doing. 6. A hydrophilic fiber assembly containing plant fibers or acrylic fibers is laid on at least a part of the ground under the multi-sheet according to any one of claims 1 to 4. Item 6. A method of using the light-reflective multi-sheet according to Item 5.