JPH10127159A - Improvement of water holding property of mold for plant cultivation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the water holding property of mold for plant cultivation, to eliminate the effect of hindering the growth of roots, to obviate the degradation in water absorptivity by fertilization and to save manpower by forming water holding layers on the lower layers of the mold for plant cultivation and covering these layers with soil, thereby forming the molding layers for plant cultivation. SOLUTION: The water holding layers contg. at least either of weakly anionic water absorptive resins, such as crosslinked matter of (co)polymers of N-vinyl carboxylic acid amide, and nonionic water absorptive resins as an essential component are formed on the lower layers of the mold for plant cultivation. These water holding layer are covered thereon with the soil to form the mold layers for plant cultivation, by which the water holding property of the mold for plant cultivation is improved. The water holding layers are preferably so formed as to exist under the rhizospheres of the plants to be cultivated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the water retention of cultivated soil and cultivated soil for agricultural and horticultural purposes, and in particular, has no growth inhibiting effect on plants, does not reduce water absorption by fertilization, and is easy and efficient to carry out. The present invention relates to a method for improving the water retention of soil for cultivation of plant.

[0002]

2. Description of the Related Art Conventionally, a water-absorbing resin has been added to cultivated soil such as agricultural and horticultural fields, cultivated soil such as nursery beds, pots, pots, planters, and the like. Methods for improving water retention have been developed. The water-absorbing resin used in such a method is mainly an ionic water-absorbing resin such as a crosslinked product of sodium polyacrylate, and the ionic water-absorbing resin is formed into granules or powder, and is used for crushed soil, cultivated soil. A method of mixing uniformly is known.

However, in order to improve the water retention of cultivated soil in the field by using the above-mentioned conventional method, the cultivated soil is dug up and crushed, and a granular or powdery resin is added so that the resin is leveled. It is necessary to mix well and adjust the ground. This method has a problem in workability, such as digging the cultivated soil sufficiently deep and requiring a large amount of cultivated soil and resin to be mixed. In particular, it has been difficult to perform the construction in a vast field. Also, when improving the water retention of the soil, such as pots, pots, and planters, the granular or powdery resin is added to the soil, and the mixture is sufficiently mixed so that the resin is averaged. Work to fill a planter or the like is required, and similarly, there is a problem in workability, and it has been particularly difficult to apply the method to a large number of pots for raising seedlings.

A crosslinked copolymer or a homopolymerized crosslinked product containing an ionic monomer in a proportion exceeding 30 mol% among the water-absorbing resins (hereinafter referred to as a water-absorbing resin having a high degree of ionization) is used as a plant root. It is known to have a growth inhibitory effect on plants, and when plants are planted in a mixture of soil and powdery or granular water-absorbent resin with a high degree of ionization, the roots of the plants avoid the resin particles, To grow through the gap. Due to this growth inhibitory effect, when the water-absorbent resin with a high degree of ionization is added in a layered form without mixing with the whole soil, the roots reach the upper surface of the water-absorbent resin layer with a high degree of ionization. Then, it could not grow any more, and there was an inconvenience that the growth of the plant body was hindered, and sometimes it withered. Although the ionic water-absorbing resin absorbs deionized water very well, the water-absorbing performance of an aqueous solution containing an ionic compound is low. Since fertilizers generally used contain a large amount of ionic compounds, there has been a problem that ionic compounds derived from fertilizers reduce the water absorption of the ionic water-absorbing resin by fertilization, and cannot exert a sufficient water retention function.

[0005]

DISCLOSURE OF THE INVENTION The present invention has no growth inhibitory effect on roots, does not reduce water absorption by fertilization,
Another object of the present invention is to provide a method for improving the water retention of a cultivation soil for plant cultivation that is efficient and has good workability.

[0006]

The method for improving water retention of soil for plant cultivation according to the present invention comprises, as a main component, a weakly anionic water-absorbent resin or a nonionic water-absorbent resin on a lower layer of a soil for plant cultivation. It is characterized in that a water retention layer is formed, and soil is covered on the water retention layer to form a soil cultivation layer for plant cultivation. The water retention layer may be formed so as to be located immediately below the rhizosphere of the plant to be cultivated. The water retaining layer may be formed by spraying a powdery or granular weak anionic water-absorbing resin or a nonionic water-absorbing resin. The formation of the water retention layer,
It may be carried out by laying a water retention sheet containing the weak anionic water-absorbing resin or the nonionic water-absorbing resin. The weakly anionic water-absorbing resin or the nonionic water-absorbing resin is a homopolymer crosslinked or copolymer crosslinked N-vinylcarboxylic acid amide, a homopolymer crosslinked or anionic copolymer crosslinked acrylamide, Crosslinked homopolymer or anionic copolymer of vinyl alcohol,
It may be a crosslinked polyoxyethylene.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, cultivated soil refers to soil for cultivating plants, a soil mixture, prepared cultivated soil, etc., for example, cultivated soil in agricultural and horticultural fields, floor soil such as nursery beds, etc.
Includes cultivation such as pots, pots, and planters. The method for improving the water retention of the soil for plant cultivation of the present invention is to use a weak anionic water-absorbent resin or a nonionic water-absorbent resin that does not inhibit the growth of the plant as a water-retention component, thereby forming the water-retention component into a layer. It is made possible to add to soil.

In the present invention, the nonionic water-absorbing resin refers to a resin which does not contain an ionic monomer and all the monomers constituting the polymer are nonionic monomers. The weak anionic water-absorbing resin refers to a resin in which the proportion of the ionic monomer is 30 mol% or less among the monomers constituting the copolymer. Examples of the weakly anionic water-absorbing resin or nonionic water-absorbing resin used in the present invention include a cross-linked polymer of polyoxyethylene (PEO), a cross-linked homopolymer of polyvinyl alcohol (PVA), or a copolymer Crosslinked product, polyacrylamide (P
AM) -based crosslinked homopolymer or copolymer, N
-It is also possible to use a homopolymer cross-linked product or a copolymer cross-linked product of vinyl carboxylic acid amide, or a mixture of two or more of these, but it has good light resistance, heat resistance and biodegradability. It is preferable to use a homopolymer cross-linked product or a copolymer cross-linked product of N-vinylacetamide (hereinafter referred to as PNVA),
More preferred is a homopolymer crosslinked product of vinylacetamide. N-vinylcarboxylic acid amide is represented by the following formula (I).

[0009]

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In the formula (I), R ₁ and R ₂ represent hydrogen or a methyl group, R ₃ represents a hydrogen, a methyl group, or an ethyl group, and R ₂ and R ₃ represent an alkylene group having 3 to 5 carbon atoms. It may be formed. Specifically, N-vinylacetamide,
N-methyl-N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylformamide, N-
Vinyl-α-pyrrolidone and the like. Examples of ionic monomers copolymerizable with N-vinylcarboxylic acid amide include (meth) acrylic acid, maleic acid, itaconic acid, 2-acrylamido-2-methyl-propanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-
Methacrylamidoethanesulfonic acid, 3-methacrylamidopropanesulfonic acid, methyl sulfonic acid acrylate, methyl methacrylate sulfonic acid, acrylic acid-2-
Ethylsulfonic acid, methacrylic acid-2-ethylsulfonic acid, acrylic acid-3-propylsulfonic acid, methacrylic acid-3-propylsulfonic acid, acrylic acid-2-methyl-3-propylsulfonic acid, methacrylic acid-2-methyl -3-propylsulfonic acid, acrylic acid-1,1′-dimethyl-2-ethylsulfonic acid, methacrylic acid-1,
1′-dimethyl-2-ethylsulfonic acid or a salt thereof. Non-ionic monomers copolymerizable with N-vinyl carboxylic acid amide include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, 2-hydroxyethyl acrylate, acrylamide, methacrylamide, acrylonitrile, methyl vinyl ketone, ethyl vinyl ketone , Vinyl acetate,
Examples include methyl vinyl ether, ethyl vinyl ether, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. The copolymerization ratio of the ionic monomer is preferably 30 mol% or less, more preferably 20 mol% or less, based on the nonionic monomer. When the copolymerization ratio of the ionic monomer is 30 mol% or less with respect to the nonionic monomer, growth is not inhibited and water retention is satisfied.

PNVA is a compound having at least two polymerizable unsaturated groups in one molecule (referred to as a "crosslinking agent"), N-vinylacetamide, and, if necessary, a copolymerized monomer formed under the condition of the absence of oxygen by radicals. It can be produced using a polymerization initiator. The polymerization process is not particularly limited, but aqueous solution polymerization, reverse phase suspension polymerization, and the like, which have been conventionally used as a method for producing a crosslinked product of sodium polyacrylate, can be employed. Specific examples thereof include JP-A-3-223304, It is described in JP-A-4-230250 and JP-A-4-346833. Specific examples of the crosslinking agent used in the production of the (co) polymer crosslinked product include N, N′-methylenebisacrylamide, triethylene glycol (meth) acrylate, pentaerythritol tri (meth) acrylate, divinylbenzene, N, N-alkylenebis (N-vinylacetamide) compounds (for example, N'-1,4-butylenebis (N
-Vinylacetamide), N, N'-diacetyl N,
N′-divinyl-1,3-bisaminomethylcyclohexane, etc.), pentaerythritol triallyl ether, tetraallyloxyethane, etc., and these can be used alone or in combination of two or more as needed. The amount of the crosslinking agent used is 2 × 10 ⁻⁴ to 10 mol%, preferably 5 × 10 ⁻⁴ to 2 mol%, based on the (co) polymerization component.
Mol% range. The polymerization initiator used in the production of the (co) polymer crosslinked product is a conventionally known peroxide, an organic or inorganic peracid or a salt thereof, or an azobis-based compound alone or in combination with a redox-based reducing agent. Among them, azobis (2-amidinopropane) dihydrochloride, 2,2′-
An azobis-based initiator such as azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride. The amount of the polymerization initiator used is 0.0% based on the (co) polymerization component.
005 to 5 mol%, particularly preferably 0.005 to 0.5
Mol%. The polymerization initiation temperature is usually about -10 to 80C, and the reaction time is about 0.5 to 30 hours. The molar ratio of the N-vinylacetamide unit to the copolymerized monomer unit of the PNVA is preferably from 100: 0 to 70:30.

In the method for improving the water retention of a soil according to the present invention, first, a water retention layer containing a weakly anionic water-absorbent resin and a nonionic water-absorbent resin as main components is formed on a lower layer of the soil for plant cultivation. The amount of the water-absorbing resin varies depending on the resin material and the drying resistance of the plant to be cultivated, but is usually preferably 50 g or more, more preferably 100 g or more per 1 m 2 of the cultivated area. With such an addition amount, the uniformity of the resin layer is maintained, and the water retention effect is sufficiently exhibited.

The method of forming the water-retaining layer is not particularly limited, and for example, a method of spraying a powdery water-absorbing resin, laying a water-retaining sheet containing the water-absorbing resin, and the like can be used.

When a powdery or granular weakly anionic water-absorbing resin or an ionic water-absorbing resin is sprayed, the particle size of the granules is preferably 0.1 to 10 mm, and 0.5 to 5 m.
m is more preferred. If the particle size is small, the formation of the water-retaining layer cannot be performed efficiently, and if the particle size is large, the liquid absorption rate becomes low, which is not preferable for use. The powdery or granular water-absorbing resin may optionally contain a binder (film-forming substance), a bulking agent, a preservative, a bactericide, an insecticide,
Antioxidants, deodorants, herbicides, soil pesticides, fertilizers, and the like can be contained or mixed. As described above, since the weak anionic water-absorbent resin or the nonionic water-absorbent resin does not have a growth inhibitory effect on the roots of the plant, even if the roots reach the depth of the water-retaining layer, the roots are separated from the resin. And can extend further below the water retention layer.

The water-retaining sheet containing the water-absorbing resin is not particularly limited. For example, a sheet-like water-absorbing or liquid-permeable carrier such as a woven fabric, a nonwoven fabric, a water-soluble film, or paper is used. Water-absorbing resin coated or affixed to a water-repellent sheet, or a water-repellent sheet, woven fabric having a structure in which two similar carriers are used and a nonionic water-absorbing resin is sandwiched between these carriers And a water-retentive sheet having a structure in which a water-absorbent resin is woven into paper or nonwoven fabric. The thickness of the water retention sheet is 0.01 to 10
mm is preferable, and 0.3 to 5 mm is more preferable. Also, it is preferable to form a large number of holes in the sheet, because even if the roots reach the depth of the water retention layer, the roots can extend further below the water retention layer through the holes. In the sheet, the weak anionic water-absorbing resin or the nonionic water-absorbing resin is usually 5 to 90%, preferably 10 to 90% of the carrier.
-30%.

It is preferable that the water retention layer is formed at a depth such that the water retention layer is immediately below a root growth range (rhizosphere) of a plant to be cultivated. Therefore, the amount of cover soil on the water retaining layer is appropriately set according to the type of plant to be cultivated.

In order to apply the method for improving water retention of cultivated soil according to the present invention to a field, a water retention layer is formed by spraying a powdery or granular water absorbent resin on the ground or laying a water retaining sheet containing the water absorbent resin. Then, the soil is leveled by covering the upper part of the water retaining layer with a cultivation soil in an amount suitable for the plant to be cultivated. Alternatively, after excavating the cultivated soil to a depth suitable for the plant to be cultivated in the field, forming a water retention layer by spraying a powdery or granular water-absorbent resin or laying a water retention sheet containing the water-absorbent resin, Can be backfilled and the ground leveled.

In the case of improving the water retention of cultivated soil such as pots, pots, planters, etc., the cultivated soil is first filled in a small amount, preferably to a depth of about several cm, and then powdered or granular After forming a water retention layer by spraying the water absorption resin or laying a water retention sheet containing the water absorption resin, it may be further filled with a commonly used soil. At this time, it is convenient and preferable to form or cut the water retention sheet according to the cross-sectional shape of a pot, a pot, a planter or the like in advance. Alternatively, a water retention sheet can be spread on the bottom of a pot, a pot, a planter, or the like, and the soil can be filled from above.

When the water retention layer is buried by the above-described method, the water retention layer absorbs and retains water when watering is performed. Then, as the surrounding soil is dried, the water retained in the water retention layer is gradually released and diffused into the surrounding soil, preventing excessive drying and over-humidification of the soil, and containing moisture in the soil. The amount can be easily controlled to a range suitable for cultivation,
Irrigation management is easy.

[0020]

【Example】

(Example) A soil obtained by mixing peat moss and vermiculite in equal amounts was placed in an eight-inch bowl (capacity: 8449.8 ml ³ , caliber: 24).
Five pieces (0 mm, bottom diameter 175 mm, height 250 mm) were filled to a thickness of several cm from the bottom, 6 g of PNVA (a crosslinked product of NVA alone) was sprayed thereon, and a young tree of Benjamin was planted on the seedlings. And cultivated for one year, the height of the plant was measured, and the average value was determined. Table 1 shows the results.

(Comparative Example 1) An eight-inch bowl was filled with only the above-mentioned soil without forming a water retaining layer. Otherwise, planting and cultivation were carried out under the same conditions as in the example, and the height from the cultivated surface of the plant to the tip of the plant after one year was measured, and the average value was obtained. The results are shown in Table 1.

(Comparative Example 2) Planting and cultivation were performed under the same conditions as in the example except that sodium polyacrylate was used instead of PNVA, and from one year after cultivation of the plant to the top of the plant. Was measured and the average value was determined. The results are shown in Table 1.

[0023]

[Table 1]

According to the results shown in Table 1, the average value of the growth amount of the Example is about 38 cm with respect to the average value of the growth amount of Comparative Example 1, and the difference of 39 cm from the average value of the growth amount of Comparative Example 2. Thus, the effect of the method for improving water retention of the present invention was confirmed.

[0025]

As described above, the method for improving the water retention of soil for cultivating plant according to the present invention is characterized in that at least one of a weakly anionic water-absorbent resin and a nonionic water-absorbent resin is formed on the lower layer of cultivated soil for plant cultivation. Is a method of forming a water retention layer containing as a main component, and covering the water retention layer with soil to form a soil culture layer for plant cultivation. Therefore, without performing the mixing work of the soil and the water-absorbent resin required by the conventional method, the buried water-retaining layer allows the cultivated soil to retain water for the entire cultivated soil. Work efficiency and labor saving are realized. In addition, by adjusting the amount of soil covering the water retaining layer, the water retaining layer can be buried at an arbitrary depth, so that the versatility is high regardless of the type of plant. Also, since at least one of the weakly anionic water-absorbent resin and the nonionic water-absorbent resin has no growth inhibitory effect on the roots of the plant, even if it is added to the soil, it does not adversely affect the growth of the plant. In addition, since the nonionic water-absorbing resin does not decrease the water absorbing performance of the aqueous solution containing the ionic compound, the water absorption of the water retaining layer does not decrease by fertilization. Further, by forming the water retaining layer so as to be located immediately below the rhizosphere of the plant to be cultivated, the effect of supplying water from the water retaining layer to the root is enhanced. Further, by forming the water retention layer by laying a water retention sheet containing a weak anionic water absorbent resin or a nonionic water absorbent resin, further labor saving can be achieved.

Claims (5)

[Claims] 1. A water retention layer containing at least one of a weakly anionic water-absorbent resin and a nonionic water-absorbent resin as a main component is formed on a lower layer of a cultivation soil for plant cultivation. A method for improving water retention of a soil for plant cultivation, comprising forming a soil cultivation layer for cultivation. 2. The method for improving water retention of a cultivation soil for plant cultivation according to claim 1, wherein the water retention layer is formed immediately below a rhizosphere of a plant to be cultivated. 3. The method for improving water retention of a soil for cultivating plants according to claim 1, wherein the formation of the water retention layer is carried out by spraying a powdery or granular water absorbent resin. 4. The method according to claim 1, wherein the formation of the water retention layer is performed by laying a water retention sheet containing the water absorbent resin. 5. A crosslinked product of a homopolymer or a copolymer of N-vinylcarboxylic acid amide, a crosslinked product of an acrylamide homopolymer or a crosslinked anionic copolymer, and a homopolymer of vinyl alcohol. The plant cultivation product according to any one of claims 1 to 4, wherein the resin is a water-absorbing resin selected from the group consisting of a crosslinked product or a crosslinked anionic copolymer, and a crosslinked product of polyoxyethylene. How to improve the water retention of the soil.