TW202128960A - Soil modification method - Google Patents

Abstract

Provided is a soil modification method that enables high soil runoff prevention and high water permeability in agricultural land. The present invention provides a soil modification method comprising a spraying step in which a soil modifying agent is sprayed onto soil, wherein the soil modifying agent contains a resin emulsion and the spraying step is performed such that the soil strength of the soil is at least 0.1 N/mm2.

Description

Soil improvement method

The invention relates to a soil modification method.

The surface soil of the cultivated land is eroded due to rainfall, etc., and the surface soil and rainwater flow away at the same time, and there are so-called soil erosion and soil erosion issues.

Patent Document 1 describes the dispersion of a soil loss prevention agent containing a resin emulsion. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2019-052289

[Problems to be Solved by Invention]

However, a method of dispersing a soil loss prevention agent that takes into account the permeability of water required for planting crops into the soil while preventing soil loss has not been established.

The present invention was made in view of the above-mentioned problems, and provides a soil modification method that can realize high soil erosion prevention and water permeability of cultivated land. [Means to solve the problem]

According to the present invention, there is provided a soil modification method including a step of spraying a soil modifier to soil, the soil modifier containing a resin emulsion, and the step of spreading the soil strength of the soil to be 0.1 N/mm ² Proceed in the same way as above.

The inventors of the present invention have found that when the strength of the soil on which the soil modifier is dispersed reaches a predetermined value or more, high soil erosion prevention and high water permeability can be obtained, thereby completing the present invention.

Various embodiments of the present invention are illustrated below. The embodiments shown below can be combined with each other. Preferably, the spreading step is performed so that the soil strength of the soil becomes 5.0 N/mm ² or less. Preferably, the spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 4 mm or more. Preferably, the spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 9 mm or more. Preferably, the spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 20 mm or less. Preferably, the spreading step is performed so that the solid content of the resin emulsion becomes 10 to 600 g/m ² . Preferably, the spreading step is performed so that the amount of the spreading liquid becomes 1000 to 8000 g/m ² . Preferably, the resin emulsion is an EVA emulsion.

The embodiments of the present invention will be described below.

1. Methods of soil improvement The soil modification method of the present invention includes a spraying step of spraying a resin emulsion on the soil.

[Soil Modifier] The soil modifier contains resin emulsion. The resin emulsion preferably contains an aqueous resin emulsion. In addition, the resin emulsion may also contain a water-soluble polymer.

＜Water-based resin emulsion＞ The type of aqueous resin emulsion is not particularly limited as long as it uses water as a dispersion medium and resin as a dispersant. As the main monomer, an aqueous resin emulsion prepared by using various olefin compounds such as vinyl acetate, acrylate, styrene, ethylene, butadiene, etc. alone or by using multiple of these compounds to polymerize can be used. Specifically, vinyl acetate resin emulsion, vinyl acetate copolymer emulsion, acrylic resin emulsion, styrene acrylate copolymer emulsion, ethylene-vinyl acetate copolymer emulsion (EVA emulsion), styrene-butadiene Olefin copolymer emulsion, vinylidene resin emulsion, polybutene resin emulsion, acrylic nitrile-butadiene resin emulsion, methacrylate-butadiene resin emulsion, pitch emulsion, epoxy resin emulsion, polyurethane resin emulsion, silicon Among them, resin emulsions containing structural units derived from vinyl acetate (vinyl acetate resin emulsion, vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, etc.) are preferred, and ethylene-vinyl acetate is more preferred. Copolymer emulsion.

The method for producing an aqueous resin emulsion is not particularly limited. For example, it can be produced by adding an emulsifier and a monomer to a dispersion medium containing water as a main component, and emulsifying and polymerizing the monomer while stirring. Examples of the emulsifier include ionic (cationic/anionic/amphoteric) surfactants and nonionic (Nonionic) surfactants. Examples of the nonionic surfactant include low-molecular-weight surfactants such as alkyl glycosides, or polymer-based surfactants such as polyethylene glycol and polyvinyl alcohol, and polymer-based surfactants are preferred. The polymer-based surfactant is particularly preferably composed of polyvinyl alcohol, and its average degree of polymerization is, for example, 200 to 2500, preferably 400 to 2200, and more preferably 500 to 2000. The higher the average degree of polymerization of polyvinyl alcohol, the higher the emulsifying and dispersing power. Therefore, in order to obtain an emulsion with a desired degree of dispersion, polyvinyl alcohol having a suitable average degree of polymerization may be used. In addition, polyvinyl alcohol can also be used in combination of multiple types of polyvinyl alcohols having different average polymerization degrees. The degree of saponification of polyvinyl alcohol is not particularly limited, and is, for example, 70% or more, preferably 80 to 95%. If the saponification is too low, the solubility in water is drastically reduced, and it cannot be dissolved unless a special dissolving method is used, making it difficult to industrially use. The lower the degree of saponification of polyvinyl alcohol, the higher the emulsifying and dispersing power. Therefore, in order to obtain an emulsion with a desired degree of dispersion, polyvinyl alcohol having a suitable degree of saponification may be used. Emulsifiers can also be used in combination with multiple different emulsifiers. The addition amount of an emulsifier is not specifically limited, For example, it is 0.5-20 mass parts with respect to 100 mass parts of dispersion media, Preferably it is 1-10 mass parts. The greater the amount of emulsifier added, the higher the emulsifying and dispersing power, so the amount of emulsifier added can be adjusted appropriately to obtain an emulsion with the desired degree of dispersion.

＜Water-soluble polymer＞ The type of water-soluble polymer is not particularly limited, and examples include methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose, and carboxymethyl. Cellulose derivatives such as base cellulose, aminomethyl hydroxypropyl cellulose, aminoethyl hydroxypropyl cellulose; starch, carrageenan, mannan, agarose, dextran, tragacanth, pectin, gum, Alginic acid or its salt; gelatin; polyvinylpyrrolidone; polyacrylic acid or its salt, polymethacrylic acid or its salt; polyacrylamide, polymethacrylamide and other acrylamides; hyaluronic acid and its salt, Chondroitin sulfate and its salts, polyvinyl alcohol, polyethyleneimine, polyethylene oxide, polyethylene glycol, polypropylene glycol, and glycerin may be used in combination of multiple types. In addition, nonionic surfactants that are miscible with water can also be used. Examples include polyoxyethylene nonyl phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether. Polyoxyethylene fatty acid esters such as oxyethylene alkyl aryl ethers or polyoxyethylene alkyl ethers, polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate Type, oxyethylene/oxypropylene block copolymer, etc.

The water-soluble polymer may be added as an emulsifier during the production of the aqueous resin emulsion, or may be added after the production of the aqueous resin emulsion.

The content of the water-soluble polymer in the aqueous resin emulsion is preferably 1-25% by mass in terms of solid content, more preferably 1-20% by mass, still more preferably 1-12% by mass, still more preferably 1-10% by mass, and further Preferably it is 1-7 mass %, More preferably, it is 2-6 mass %. By containing an appropriate amount of water-soluble polymer, the water permeability is improved.

[Spreading method] The method of spreading the soil modifier to the soil is not particularly limited. For example, when spreading on a small area, you can use a watering can or a power spreader, and when spreading on a large area, you can use a hydraulic seeder or boom sprayer. <Soil strength> The spreading step is performed so that the soil strength of the soil becomes 0.1 N/mm ² or more, preferably 0.5 N/mm ² or more. With such a range, sufficient soil erosion prevention and water permeability can be obtained. In addition, the spreading step is preferably performed so that the soil strength of the soil becomes 5.0 N/mm ² or less, and more preferably 4.0 N/mm ² or less. By setting it in such a range, sufficient soil erosion prevention and water permeability can be obtained, and adverse effects on rooting and germination of plants are small. The aforementioned soil strength is specifically, for example, 0.1, 0.2, 0.3, 0.4, ^{0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 3.8, 4.0, 4.5, 5.0 N/mm 2,} It may be in the range between any two numerical values exemplified here.

＜Thickness of fixing layer＞ The spreading step is performed so that the thickness of the fixing layer formed by spreading is preferably 4 mm or more, and more preferably 9 mm or more. With such a range, sufficient soil erosion prevention and water permeability can be obtained. In addition, the spreading step is performed so that the thickness of the fixing layer formed by spreading is preferably 20 mm or less, and more preferably 18 mm or less. The thickness of the fixing layer is specifically, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm, and it may be the value exemplified here. Within the range between any two values in.

In the spreading step, it is preferable to spread so that the amount of solids derived from the soil modifier spread on the soil per unit area is preferably 10 to 600 g/m ² , and more preferably 100 to 500 g/m ² . With such a range, high soil strength can be obtained.

In the spreading step, it is preferable to spread so that the amount of spreading liquid per unit area of soil is preferably 1000 to 8000 g/m ² , and more preferably 2000 to 4000 g/m ² . With such a range, high soil strength and sufficient anchor layer thickness can be obtained.

The soil modification method of the present invention may further include a drying step of drying the soil after dispersing the soil modification agent on the soil. The drying step may be natural drying or forced drying by heating or blowing air. By drying the soil, the resin in the soil modifier is firmly combined with the soil, and it is easy to exert the effect of improving water permeability. [Example]

Hereinafter, embodiments of the present invention will be described. In the following description, unless otherwise specified, "parts", "%" and "ratio" mean "parts by mass", "% by mass" and "mass ratio", respectively.

1. Manufacturing example of soil modifier As an emulsifier, polyvinyl alcohol (DENKA POVAL B-05 (degree of saponification 88 mol%, average degree of polymerization 600, manufactured by Denka Corporation) 4.1 parts and DENKA POVAL B-17 (degree of saponification 88 mol%, average degree of polymerization 1700, DENKA Co., Ltd.) 1.5 parts, 0.1 part of formamidine sulfinic acid as an auxiliary, 0.2 part of sodium acetate, 0.005 part of ferrous sulfate heptahydrate, and 0.01 part of tetrasodium ethylenediaminetetraacetic acid are dissolved in 100 parts of pure water, After putting the dissolved substance into a high-pressure polymerization tank with a stirrer, 83 parts of vinyl acetate monomer and 20 parts of ethylene were filled with stirring to set the internal liquid temperature to 55°C, and then an aqueous solution of ammonium persulfate was continuously added for polymerization. From the high-pressure polymerization tank Starting from the moment when the internal pressure dropped to 4.3 MPa, 26 parts of vinyl acetate monomer were added in batches over 2 hours. At the end of the polymerization, an aqueous solution of tert-butyl hydroperoxide was added, and the polymerization was continued until the amount of unreacted vinyl acetate monomer was less than 2%. The remaining ethylene after the polymerization was purged, and the unreacted vinyl acetate monomer in the resulting emulsion was removed under reduced pressure to obtain a resin emulsion 1 having an unreacted vinyl acetate monomer of 0.5% or less. The solid content rate of the obtained resin emulsion 1 was measured in accordance with JIS K 6828. The drying conditions were drying at 105°C for 3 hours. The solid content rate is 55%.

2. Examples, comparative examples, reference examples ＜Preparation of test soil 1＞ Fill the filling container with soil as described below, and smooth the soil surface non-rolling with a brush. The dispersion solution prepared by using the resin emulsion 1 and pure water was dispersed as a soil modifier. Spread and maintain according to the spreading conditions in Table 1. Soil type: Iwase sand (produced in Ibaraki Prefecture) Soil filling container: SUS square flat base plate (internal size: W253×L338×H60mm) Soil filling volume: 7.0±0.5kg/container (no rolling) Soil moisture content before resin emulsion spreading: 1.6% Spreading method: spray Maintenance conditions: 23℃ indoor (use air-conditioning to manage temperature)/1 week

＜Measurement of soil strength＞ Gradually apply a load to the surface of the test soil 1, and use IMADA’s digital dynamometer DS2-500N (using a φ16.2mm round flat fitting) to measure the maximum value of the load when the fixed layer is broken, and use the maximum load Divide the value by the contact area between the round flat fitting and the soil surface to calculate the soil strength. Measure with N=5, remove the maximum and minimum values, and calculate the average value with N=3.

＜Measurement of fixing layer thickness＞ The fixed layer on the surface of the test soil 1 was peeled off using tweezers, and the thickness of the fixed layer was measured using a vernier caliper. Measure with N=5, remove the maximum and minimum values, and calculate the average value with N=3.

＜Preparation of test soil 2＞ Fill the filling container with soil as described below, and smooth the soil surface non-rolling with a brush. The dispersion solution prepared by using the resin emulsion 1 and pure water was dispersed as a soil modifier. Spread and maintain according to the spreading conditions in Table 1. Soil type: Iwase sand (produced in Ibaraki Prefecture) Soil filling container: Win planter square 32 type (internal dimensions: 28cm on four sides × 21cm in height) Soil filling volume: 16.5±0.5kg/container (no rolling) Soil moisture content before resin emulsion spreading: 1.6% Spreading method: spray Curing conditions: 23℃ indoor (only temperature control with air conditioner)/1 week

＜Water permeability＞ The planter was fixed so that the surface of the test soil 2 became an inclined angle of 10 degrees, and water was sprayed on the entire soil surface from a height of 1.5 m at 200 mm/h for 30 minutes (device: Oki Rika Co., Ltd. rainfall device DIK-6000). Recover all the water, including soil, that flowed out from the edge of the planter during the spread of water, separate the soil and water, and measure the quality of the water flowing out of the surface. The test is to rain every day and repeat 3 times. The water permeability is calculated by the following formula from the three cumulative amounts of the amount of scattered water and the mass of the surface effluent water. Water permeability (%) = 100 × (spreading water volume (kg)-surface water outflow mass (kg)) / scattering water volume (kg)

<Amount of soil loss> The mass of red soil separated when measuring the quality of surface water flowing out is measured, and the amount of soil loss from the surface is calculated by the following formula from the cumulative amount of three times. Soil loss (g/m ² ) = soil quality (g) / opening area of the planter (m ² )

[Table 1]

Claims (8)

A soil modification method, comprising a step of dispersing a soil modifier to soil, the soil modifier containing a resin emulsion, and the dispersing step is performed such that the soil strength of the soil becomes 0.1 N/mm ² or more . The method according to claim 1, wherein the spreading step is performed so that the soil strength of the soil becomes 5.0 N/mm ² or less. The method according to claim 1 or 2, wherein: The spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 4 mm or more. The method according to claim 3, wherein: The spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 9 mm or more. The method according to claim 1 or 2, wherein: The spreading step is performed so that the thickness of the fixing layer formed by the spreading becomes 20 mm or less. The method according to claim 1 or 2, wherein the spreading step is performed so that the solid content of the resin emulsion becomes 10 to 600 g/m ² . The method according to claim 1 or 2, wherein the spreading step is performed so that the amount of spreading liquid becomes 1000 to 8000 g/m ² . The method according to claim 1 or 2, wherein: The resin emulsion is an EVA emulsion.