Soil-improving agent

Abstract

To provide a soil-improving agent that contains a lignin-based compound as an active ingredient and is capable of efficiently increasing the amounts of microorganisms and inorganic components in soil.SOLUTION: A soil-improving agent includes a lignin sulfonic acid having a phenolic hydroxyl group content of 0.1-5.0 wt.%, a methoxyl group content of 1.0-15.0 wt.%, and a content of sulfur atoms from sulfone groups of at least 2.0%. An improved soil composition includes the soil-improving agent and soil. A method for preparing improved soil includes adding the soil-improving agent to soil. A method for producing plants comprises using the improved soil composition to produce plants.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a soil conditioner. [Background technology]

[0002] Soil properties are important in agriculture and other industries that use soil. In particular, soil that is rich in microorganisms and inorganic components has the advantage of suppressing crop diseases, preventing damage from continuous cropping, and enabling organic farming.

[0003] For example, Patent Document 1 describes a soil conditioner containing as an active ingredient a lignin decomposition product such as soda lignin, which has an aldehyde yield of 5% by mass or more by alkali nitrobenzene oxidation, a weight-average molecular weight of 300 to 100,000, and a contact angle with water of 15° or more, and which reduces soil hardness. Patent Document 2 describes a soil conditioner containing a lignin derivative extracted from a lignin-containing material with a solvent containing a specific organic solvent, which promotes soil aggregate formation while maintaining the bacterial flora structure of the soil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-190448 A [Patent Document 2] Patent Publication No. 2021-80367 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Documents 1 and 2 do not disclose any effect on the proliferation of microorganisms or the increase of inorganic components in soil. The present invention aims to provide a soil improvement agent that contains a lignin compound as an active ingredient and can efficiently increase the amount of microorganisms and inorganic components in soil. [Means for solving the problem]

[0006] The present invention provides the following [1] to [9]. [1] A soil conditioner comprising lignin sulfonic acid having a phenolic hydroxyl group content of 0.1 to 5.0% by weight, a methoxyl group content of 1.0 to 15.0% by weight, and a sulfur atom content derived from sulfonic groups of 2.0% or more. [2] Lignosulfonic acid, The sulfur atom content is 1.0% by weight or more. The sodium atom content is 0.3% by weight or more, and The reducing sugar content is 0.1% by weight or more. The agent according to [1], which satisfies at least one of the above. [3] The agent according to [1] or [2], wherein the carboxyl group content of the lignosulfonic acid is 0.1 to 4.5 mmol / g. [4] The agent according to any one of [1] to [3], wherein the weight average molecular weight (RI) of the lignosulfonic acid is 3,000 or more. [5] The agent according to any one of [1] to [4], wherein the lignin sulfonic acid has a substituent derived from a (poly)alkylene oxide. [6] The agent according to any one of [1] to [5], wherein the soil is agricultural soil. [7] An improved soil composition comprising the agent according to any one of [1] to [6] and soil. [8] A method for preparing improved soil, comprising adding the agent according to any one of [1] to [6] to soil. [9] A method for producing a plant, comprising producing a plant using the improved soil composition according to [7]. Effect of the Invention

[0007] According to the present invention, a soil conditioner applicable to various soils is provided. The soil conditioner of the present invention can increase microorganisms in the soil and increase inorganic components. Therefore, by using the soil conditioner in the agricultural field, it can increase the yield of agricultural crops, and organic farming can be realized and spread. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [1. Lignosulfonic acid components] The soil conditioner of the present invention contains a lignosulfonic acid component.

[0009] [Lignosulfonic acid] The lignosulfonic acid component is a component mainly containing lignosulfonic acid and is usually derived from sulfite cooking of pulp. Lignosulfonic acid is a compound having a skeleton in which a carbon atom at the α-position of the side chain of the hydroxyphenylpropane structure of lignin is cleaved to introduce a sulfone group.

[0010] Lignosulfonic acid may take the form of a salt, such as a monovalent metal salt, a divalent metal salt, an ammonium salt, or an organic ammonium salt, of which calcium salt, magnesium salt, sodium salt, or a mixed calcium-sodium salt is preferred.

[0011] [Substituent] Lignosulfonic acid contains a substituent other than a sulfone group. The substituent may be a substituent derived from lignin, or may be a substituent that is introduced by modification treatment and is not originally contained in lignin. Examples of the substituent include a hydroxyl group (phenolic hydroxyl group, alcoholic hydroxyl group), a methoxyl group, a carboxyl group, a sulfomethyl group, an aminomethyl group, and a (poly)alkylene oxide group. Of these, it is more preferable to contain a phenolic hydroxyl group, a methoxyl group, a sulfone group, and a (poly)alkylene oxide group in a predetermined range. This can promote plant growth.

[0012] -Phenol hydroxyl group- The phenolic hydroxyl group is generally a hydroxyl group directly bonded to an aromatic ring such as benzene. The phenolic hydroxyl group content is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, even more preferably 1.0% by weight or more, and even more preferably 1.1% by weight or more, based on the total amount of the lignosulfonic acid component. The upper limit is preferably 5.0% by weight or less, more preferably 4.0% by weight or less, even more preferably 3.0% by weight or less, and even more preferably 2.7% by weight or less. Therefore, the phenolic hydroxyl group content of the lignosulfonic acid is preferably 0.1 to 5.0% by weight, more preferably 0.5 to 4.0% by weight, even more preferably 1.0 to 3.0% by weight, and even more preferably 1.1 to 2.7% by weight. The phenolic hydroxyl group content can be quantified from the absorbance measured by a spectrophotometer.

[0013] -Methoxyl group- The methoxyl group is a group represented by the formula: -OCH3. The methoxyl group content is preferably 1.0% by weight or more, more preferably 3.0% by weight or more, even more preferably 5.0% by weight or more, and even more preferably 6.0% by weight or more, based on the total amount of the lignosulfonic acid component. The upper limit is preferably 15.0% by weight or less, more preferably 13.0% by weight or less, even more preferably 12.0% by weight or less, and even more preferably 11.5% by weight or less. Therefore, the methoxyl group content is preferably 1.0 to 15.0% by weight, more preferably 3.0 to 13.0% by weight, even more preferably 5.0 to 12.0% by weight, and even more preferably 6.0 to 11.5% by weight. The methoxyl group content of lignin can be measured by the Viebock and Schwappach method.

[0014] -Sulfonic acid group- A sulfone group (sulfonic acid group, sulfo group) is generally represented by the formula: -SO3 - M +(M is a counter cation (e.g., H, Na, Ca, Mg, NH4)). The sulfonic group content can be represented by the content of sulfur atoms derived from sulfonic groups (sulfonic group S content). The sulfonic group S content is preferably 2.0% or more, more preferably 3.0% or more, even more preferably 4.0% or more, and even more preferably 4.5% or more, based on the total amount of the lignosulfonic acid component. There is no particular upper limit, but it is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 8.0% or less, and even more preferably 7.0% or less. Therefore, the sulfonic group S content is preferably 2.0 to 10.0%, more preferably 3.0 to 9.0%, even more preferably 4.0 to 8.0%, and even more preferably 4.5 to 7.0%. The sulfonic group S content can be determined by subtracting the inorganic sulfur atom content from the total sulfur atom content in the lignosulfonic acid.

[0015] -Carboxyl group- A carboxyl group generally has the formula: -COOM + (M is a counter cation (e.g., H, Na, Ca, Mg, NH4)). The carboxyl group content is preferably within a predetermined range. That is, it is preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, and even more preferably 0.5 mmol / g or more, per weight of the lignosulfonic acid component. The upper limit is preferably 4.5 mmol / g or less, more preferably 4.0 mmol / g or less, and even more preferably 3.0 mmol / g or less. Therefore, the carboxyl group content is preferably 0.1 to 4.5 mmol / g, more preferably 0.3 to 4.0 mmol / g, and even more preferably 0.5 to 3.0 mmol / g. The carboxyl group content can be determined by neutralization titration.

[0016] -(Poly)alkylene glycol group- The (poly)alkylene glycol group is a substituent derived from a (poly)alkylene oxide. The average number of moles added of the alkylene oxide units constituting the polyalkylene glycol is usually 1 or more, 5 or more, or 10 or more, preferably 15 or more, more preferably 20 or more, even more preferably 25 or more, or 30 or more, and even more preferably 35 or more. This can improve the dispersibility. Among them, it is preferable that the number is 50 or more, 60 or more, 70 or more, 80 or more, or 90 or more, because the water surface spreadability is further improved. The upper limit is usually 300 or less or 200 or less, preferably 190 or less, more preferably 180 or less, and even more preferably 170 or less. This can suppress the decrease in dispersion retention. Therefore, the average number of moles added is usually 10 to 200, preferably 15 to 190, more preferably 20 to 180, and even more preferably 25 to 170. On the other hand, it may be preferably 25 to 300, more preferably 30 to 200, and even more preferably 35 to 150. The number of carbon atoms of the polyalkylene glycol is not particularly limited, and is usually 2 to 18, preferably 2 to 4, and more preferably 2 to 3. Examples of the alkylene oxide unit include an ethylene oxide unit, a propylene oxide unit, and a butylene oxide unit, and an ethylene oxide unit or a propylene oxide unit is preferable. Examples of lignin sulfonic acids containing a (poly)alkylene oxide group include lignin derivatives described in WO 2021 / 066166.

[0017] [Inorganic components] The lignosulfonic acid component may further contain an inorganic component. Examples of the inorganic component include inorganic salts of sulfur, calcium, sodium, magnesium, nitrogen, phosphorus, potassium, iron, etc., ammonia, oxides of these inorganic salts (e.g., sulfur oxide, magnesium oxide, calcium oxide), hydroxides (e.g., magnesium hydroxide, calcium hydroxide, sodium hydroxide, ammonium hydroxide), carbonates (e.g., calcium carbonate, sodium carbonate), and nitric acid. The form of the inorganic component is not particularly limited, and may be a counter cation of lignosulfonic acid or a free inorganic component (e.g., an inorganic component added during the production of lignosulfonic acid). Of these, it is preferable to contain at least one of sulfur, calcium, sodium, magnesium, nitrogen, phosphorus, and potassium.

[0018] -Sulfur ion- The content of sulfur ions can be expressed as the content of sulfur atoms (total S content) contained in lignosulfonic acid. The total S content is preferably 1.0% by weight or more, 2.0% by weight or more, or 3.0% by weight or more, more preferably 4.0% by weight or more, and even more preferably 5.0% by weight or more. There is no particular upper limit, but it is preferably 10.0% by weight or less, more preferably 9.0% by weight or less, and even more preferably 8.0% by weight or less. Therefore, the S content is preferably 1.0 to 10.0% by weight, 2.0 to 10.0% by weight, or 3.0 to 10.0% by weight, more preferably 4.0 to 9.0% by weight, and even more preferably 5.0 to 8.0% by weight. The total S content can be quantified by ICP emission spectrometry.

[0019] -Sulfur oxide- Lignosulfonic acid may contain sulfur oxide. Examples of sulfur oxide include sulfur dioxide (SO2), sulfur trioxide (SO3), and sulfur tetroxide (SO4), and SO3 and SO4 are preferred. The SO3 content is usually 0% or more, preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and even more preferably 0.01% by weight or more or 0.04% by weight or more, since SO3 may change to the SO4 form. The upper limit is preferably 3.0% by weight or less, more preferably 2.0% by weight or less, even more preferably 1.0% by weight or less, and even more preferably 0.5% by weight or less. Therefore, the SO3 content is usually 0 to 3.0% by weight, preferably 0.001 to 3.0% by weight, more preferably 0.005 to 2.0% by weight, even more preferably 0.01 to 1.0% by weight, and even more preferably 0.04 to 0.5% by weight. The SO4 content is preferably 0.2% by weight or more, more preferably 0.4% by weight or more, and even more preferably 0.5% by weight or more, 2.0% by weight or more, or 3.0% by weight or more. The upper limit is preferably 10% by weight or less, more preferably 9.5% by weight or less, and even more preferably 9.0% by weight or less. Therefore, the SO4 content is preferably 0.2 to 10% by weight, more preferably 0.4 to 9.5% by weight, even more preferably 0.5 to 9.0% by weight, and even more preferably 2.0 to 9.0% by weight or 3.0 to 9.0% by weight. The sulfur oxide content can be quantified by ion chromatography.

[0020] -Proportion of sulfonic S in the total S content- The ratio of the sulfur atom content derived from sulfonic groups to the total sulfur atom content in lignosulfonic acid is preferably 0.5 or more, more preferably 0.6 or more, and the upper limit is usually 0.9 or less, preferably 0.8 or less, but is not particularly limited.

[0021] -The ratio of SO3 to SO4- The ratio of the SO3 content to the SO4 content in lignosulfonic acid is usually 0 or more, preferably 0.01 or more, more preferably 0.02 or more, and the upper limit is preferably 0.05 or less, more preferably less than 0.03.

[0022] -Sodium ions, calcium ions, magnesium ions- Na + , Ca 2+ , Mg 2+ Each ion content can be expressed as the content of each atom. The sodium atom content (Na content) is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, and even more preferably 1.0% by weight or more. There is no particular upper limit, but it is preferably 10.0% by weight or less, more preferably 9.0% by weight or less, and even more preferably 8.0% by weight or less. Therefore, the Na content is preferably 0.3 to 10.0% by weight, more preferably 0.5 to 9.0% by weight, and even more preferably 1.0 to 8.0% by weight. The calcium atom content (Ca content) is preferably 0.001% by weight or more, more preferably 0.01% by weight or more, and even more preferably 0.03% by weight or more. The upper limit is preferably 3.0% by weight or less, and more preferably 1.0% by weight or less. Therefore, the Ca content is preferably 0.001 to 3.0% by weight, more preferably 0.01 to 1.0% by weight, and even more preferably 0.03 to 1.0% by weight. The magnesium atom content (Mg content) is preferably 0.05% by weight or more, more preferably 0.07% by weight or more, and even more preferably 0.1% by weight or more, 0.5% by weight or more, 1.0% by weight or more, 2.0% by weight or more, 3.0% by weight or more, or 3.2% by weight or more. The upper limit is preferably 10.0% by weight or less, more preferably 8.0% by weight or less, and even more preferably 5.0% by weight or less. Therefore, the Mg content is preferably 0.05 to 10.0% by weight, more preferably 0.07 to 8.0% by weight, and further preferably 0.1 to 5.0% by weight, 0.5 to 5.0% by weight, 1.0 to 5.0% by weight, 2.0 to 5.0% by weight, 3.0 to 5.0% by weight, or 3.2 to 5.0% by weight. The Na content, Ca content, and Mg content can be quantitatively determined by an inductively coupled plasma (ICP) method.

[0023] -Reducing sugars- The lignin sulfonic acid component preferably further contains reducing sugars. In this specification, reducing sugars refer to sugars that have reducing properties, that is, sugars that have the property of generating aldehyde groups or ketone groups in a basic solution. Examples of reducing sugars include all monosaccharides; disaccharides such as maltose, lactose, arabinose, and invert sugars of sucrose; and polysaccharides. Reducing sugars generally include cellulose, hemicellulose, and their decomposition products. Examples of decomposition products of cellulose and hemicellulose include monosaccharides such as rhamnose, galactose, arabinose, xylose, glucose, mannose, and fructose; oligosaccharides such as xylooligosaccharides and cellooligosaccharides; and modified products thereof. Modified products are chemically modified products such as oxidation and sulfonation, and examples of such modified products include sugar derivatives in which functional groups such as hydroxyl groups, aldehyde groups, carbonyl groups, and sulfo groups are introduced into the sugar skeleton, and compounds in which two or more of the sugar derivatives (two types) are bonded.

[0024] The reducing sugar content is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, and even more preferably 0.5% by weight or more, or 2.0% by weight or more. The upper limit is preferably 35% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less. Therefore, the reducing sugar content is preferably 0.1 to 35% by weight, more preferably 0.3 to 30% by weight, and even more preferably 0.5 to 25% by weight, or 2.0 to 25% by weight. The reducing sugar content can be calculated as a glucose equivalent value by the Somogyi-Schaffer method.

[0025] [Other ingredients] The lignin sulfonic acid component may contain components other than those mentioned above. Examples of the components include organic components and ash. Examples of the organic components include low molecular weight organic substances (e.g., organic acids having 5 or less carbon atoms) such as formic acid, acetic acid, propionic acid, valeric acid, pyruvic acid, succinic acid, and lactic acid. The low molecular weight organic substances may be contained alone or in combination.

[0026] The amount of low molecular weight organic matter is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and even more preferably 1% by weight or more. The upper limit is preferably 25% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less. Therefore, the amount of low molecular weight organic matter is preferably 0.01 to 25% by weight, more preferably 0.1 to 20% by weight, and even more preferably 1 to 15% by weight. The amount of low molecular weight organic matter can be measured, for example, as the amount of acetic acid fraction in the fractionation and quantification of organic acids by silica gel column chromatography after ether extraction.

[0027] [Weight average molecular weight (RI)] The weight average molecular weight (RI) of the lignin sulfonic acid component is preferably 3,000 or more, more preferably 3,500 or more, even more preferably 3,700 or more, and even more preferably 4,000 or more. The upper limit is not particularly limited, but is preferably 50,000 or less, more preferably 40,000 or less, and even more preferably 35,000 or less. Therefore, the weight average molecular weight (RI) is preferably 3,000 to 50,000, more preferably 3,500 to 50,000, even more preferably 3,700 to 40,000, and even more preferably 4,000 to 35,000. In this specification, the weight average molecular weight (RI) is the weight average molecular weight determined by GPC using a differential refractive index detector (RI).

[0028] [Weight average molecular weight (UV)] The weight average molecular weight (UV) of the lignosulfonic acid component is preferably 4,000 or more, more preferably 5,000 or more, and even more preferably 6,000 or more. The upper limit is not particularly limited, but is more preferably 70,000 or less, even more preferably 60,000 or less, and even more preferably 50,000 or less. Therefore, the weight average molecular weight (UV) is preferably 4,000 to 70,000, more preferably 5,000 to 60,000, and even more preferably 6,000 to 50,000. In this specification, the weight average molecular weight (UV) is a weight average molecular weight determined by GPC using an ultraviolet-visible absorbance detector.

[0029] -Ratio of weight average molecular weight RI / UV- The ratio of the weight average molecular weight (RI) to the weight average molecular weight (UV) is preferably 0.95 or less, more preferably 0.93 or less. The lower limit is usually 0.4 or more, preferably 0.5 or more, and is not particularly limited.

[0030] As the lignin sulfonic acid component, for example, one having the above-mentioned substituents and inorganic component amounts may be selected from Sanlighon (scheduled to be sold by Nippon Paper Industries Co., Ltd. after July 2022) and used.

[0031] [1.2 Method for producing lignosulfonic acid components] The method for producing the lignosulfonic acid component is not particularly limited, but it can be produced, for example, by a method of subjecting a lignocellulose raw material to a sulfite treatment, or a method of decomposing lignin and sulfonating it. By adjusting the production conditions, it is possible to adjust the type and content of the substituents possessed by the lignosulfonic acid component, and the type and content of each component such as inorganic components and reducing sugars.

[0032] -Raw materials- Lignocellulose raw materials as an example of raw materials are not particularly limited as long as they contain lignocellulose in the constituents. For example, pulp raw materials such as wood and non-wood can be mentioned. For example, wood can be coniferous wood such as radiata pine, Yezo spruce, red pine, cedar, and cypress, and broadleaf wood such as white birch and beech. The age of the wood and the part from which it was harvested do not matter. Therefore, wood harvested from trees of different ages or wood harvested from different parts of a tree may be used in combination. For example, non-wood can be bamboo, kenaf, reed, and rice. The lignocellulose raw materials may be one type alone or two or more types in combination.

[0033] Other examples of lignin as the raw material include naturally occurring lignin and artificially produced lignin (for example, dehydrogenation polymerized product of hydroxycinnamic alcohol analogues).

[0034] -Sulfurous acid treatment- The sulfite treatment can be carried out by contacting the lignocellulosic raw material with at least one of sulfurous acid and a sulfite salt. The conditions for the sulfite treatment are not particularly limited as long as they allow introduction of a sulfo group to the α-carbon atom of the side chain of lignin contained in the lignocellulosic raw material.

[0035] The sulfite treatment is preferably carried out by sulfite cooking, which allows the lignin in the lignocellulosic raw material to be sulfonated more quantitatively. The sulfite cooking is a method in which the lignocellulosic raw material is reacted at high temperature in a solution of at least one of sulfurous acid and a sulfite salt (e.g., aqueous solution: cooking liquid). This method has been established and is being carried out industrially as a method for producing sulfite pulp, and is therefore advantageous in terms of economy and ease of implementation.

[0036] When sulfite cooking is carried out, examples of the sulfite salt include magnesium salts, calcium salts, sodium salts and ammonium salts.

[0037] The sulfurous acid (SO2) concentration in at least one of the sulfurous acid and sulfite solutions is not particularly limited, but the ratio of mass (g) of SO2 to 100 mL of reaction solution is preferably 1 g / 100 mL or more, and more preferably 2 g / 100 mL or more when sulfite cooking is performed. The upper limit is preferably 20 g / 100 mL or less, and more preferably 15 g / 100 mL or less when sulfite cooking is performed. The SO2 concentration is preferably 1 g / 100 mL to 20 g / 100 mL, and more preferably 2 g / 100 mL to 15 g / 100 mL when sulfite cooking is performed.

[0038] The pH value of the sulfurous acid treatment is not particularly limited, but is usually 10 or less. When sulfurous acid cooking is performed, it is preferably performed under acidic conditions, more preferably pH 5 or less, and even more preferably pH 3 or less. This allows lignin derivatives (e.g., lignin sulfonic acid) to be efficiently extracted, and pulp of higher quality can be obtained. The lower limit of the pH value is preferably 0.1 or more, and when sulfurous acid cooking is performed, it is more preferably 0.5 or more. The pH value during the sulfurous acid treatment is preferably 0.1 to 10, and when sulfurous acid cooking is performed, it is more preferably 0.5 to 5, and even more preferably 0.5 to 3.

[0039] The temperature of the sulfite treatment is not particularly limited, but is preferably 170° C. or lower, and more preferably 150° C. or lower when sulfite cooking is performed. The lower limit is preferably 70° C. or higher, and more preferably 100° C. or higher when sulfite cooking is performed. The temperature condition of the sulfite treatment is preferably 70 to 170° C., and more preferably 100 to 150° C. when sulfite cooking is performed. The treatment time for the sulfurizing treatment is not particularly limited, and although it depends on the conditions of the sulfurizing treatment, it is preferably 0.5 to 24 hours, and more preferably 1.0 to 12 hours.

[0040] In the sulfite treatment, it is preferable to add a compound that supplies a counter cation to the lignosulfonic acid. By adding a compound that supplies a counter cation, the pH value in the sulfite treatment can be kept constant. Examples of compounds that supply counter cations include MgO, Mg(OH)2, CaO, Ca(OH)2, CaCO3, NH3, NH4OH, NaOH, NaHCO3, and Na2CO3. The counter cation is preferably a magnesium ion or a sodium ion.

[0041] In the sulfurous acid treatment, when a solution of at least one of sulfurous acid and sulfite is used, the solution may contain, in addition to SO2, the above-mentioned counter cation (salt) and a digestion and penetration agent (e.g., a cyclic ketone compound such as anthraquinone sulfonate, anthraquinone, or tetrahydroanthraquinone), as necessary.

[0042] There is no limitation on the equipment used in the sulfite treatment, and for example, generally known dissolving pulp manufacturing equipment can be used.

[0043] The intermediate product may be separated from the solution of at least one of sulfurous acid and sulfite salts by a conventional method, such as a method for separating the sulfurous acid digestion wastewater after the sulfurous acid digestion (e.g., filtration).

[0044] The lignosulfonic acid obtained by the sulfite treatment (e.g., as the filtrate or filtration residue after filtering insoluble matters in a sulfite solution, preferably as the filtrate) may be used as the lignosulfonic acid component, which is an active ingredient, either as is or after concentrating as necessary. On the other hand, if necessary, other treatments may be further carried out. This can increase the purity or introduce other substituents that are not inherently contained in the raw material. Examples of other treatments include alkali treatment, oxidation treatment, dialysis treatment, ultrafiltration treatment, modification treatment, and combinations of these.

[0045] (Alkaline treatment) The alkaline treatment can be carried out by placing the target sample under alkaline conditions. Placing the sample under alkaline conditions usually means placing the sample in an aqueous solution having a pH value of 8 or more, preferably a pH value of 9 or more. The upper limit of the pH value is usually 14.

[0046] In the alkali treatment, an alkaline substance is usually brought into contact with the sulfite treatment product. The alkaline substance is not particularly limited, but examples thereof include calcium hydroxide, magnesium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonia. Among these, sodium hydroxide and calcium hydroxide are preferred. The alkaline substance may be used alone or in combination of two or more.

[0047] Examples of a method for contacting an alkaline substance with the sulfurous acid treated product include a method of preparing a dispersion or solution (e.g., an aqueous dispersion or aqueous solution) of the sulfurous acid treated product and adding an alkaline substance to the dispersion or solution, and a method of adding a solution or dispersion (e.g., an aqueous dispersion or aqueous solution) of the alkaline substance to the sulfurous acid treated product.

[0048] The temperature of the alkali treatment is not particularly limited, but is preferably 40° C. or higher, and more preferably 60° C. or higher. The upper limit is preferably 150° C. or lower, more preferably 120° C. or lower, and even more preferably 110° C. or lower.

[0049] The amount of the alkaline substance in the alkali treatment is preferably 0.5 to 40 mass %, more preferably 1.0 to 30 mass %, based on the solids mass of the sulfurous acid treated product, or, when an aqueous solution or dispersion is prepared by dispersing the alkali treated extract in an aqueous solvent (e.g., water), based on the mass of the aqueous solution or dispersion.

[0050] The time for the alkali treatment is not particularly limited, but is preferably 0.1 hours or more, more preferably 0.5 hours or more, and is preferably 10 hours or less, more preferably 6 hours or less.

[0051] Prior to the alkali treatment, the sulfite-treated product may be dissolved, dispersed, or the concentration adjusted (preparation of a solution or dispersion in an aqueous solvent such as water) as necessary. Dispersion can be performed by passing through a disc refiner, adding to a mixer or disperser, kneading, or the like. The concentration can be adjusted, for example, by using an aqueous solvent such as water.

[0052] (Oxidation treatment) The oxidation treatment can be carried out on the treated product obtained after the sulfurous acid treatment (for example, the filtrate after filtration) or the treated product after the alkali treatment. The oxidation treatment can be carried out by using an appropriate oxidizing agent. When the oxidizing agent is a gas, the oxidation treatment can be carried out by bubbling the gas into the filtrate. When the oxidizing agent is a liquid, the oxidation treatment can be carried out by adding the liquid to the filtration residue or the filtrate. The oxidizing agent is preferably air, oxygen, hydrogen peroxide, ozone, or a combination thereof. The oxidation treatment is preferably carried out under alkaline conditions (alkaline oxidation treatment). The treatment pH of the alkaline oxidation treatment is usually 8 or more, preferably 10 or more, and more preferably 12 or more. The temperature of the oxidation treatment is usually 20 to 200°C, and preferably 50 to 180°C. The time of the oxidation treatment is usually preferably 0.1 hours or more, and more preferably 0.5 hours or more. The upper limit is preferably 5 hours or less, and more preferably 3 hours or less.

[0053] (Dialysis or UF treatment) The dialysis treatment can be performed on the treated product obtained after the sulfite treatment (for example, the filtrate after filtration). Examples of the dialysis membrane include cellulose-based membranes such as cellulose acetate, and synthetic polymer-based membranes such as ethylene vinyl alcohol, polyacrylonitrile, polymethyl methacrylate, polysulfone, and polyethersulfone, and the molecular weight fraction is usually 5,000 to 100,000, preferably 7,000 to 80,000, and more preferably 10,000 to 50,000.

[0054] Instead of dialysis, ultrafiltration (UF) can be used. As the UF membrane, a known UF membrane can be used. For example, a hollow fiber membrane, a spiral membrane, a tubular membrane, and a flat membrane can be used. As the material of the UF membrane, a known material can be used. For example, cellulose acetate, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, and ceramic can be used. The UF membrane may be a commercially available product.

[0055] The molecular weight cutoff of the UF membrane is preferably 5,000 to 30,000, more preferably 10,000 to 25,000, and even more preferably 15,000 to 23,000. When a UF membrane with a molecular weight cutoff of 5,000 or more is used, it is possible to prevent the separation speed of the treatment liquid from being excessively slowed. In addition, when a UF membrane with a molecular weight cutoff of 30,000 or less is used, it is possible to prevent lignin from being unable to be separated from the treatment liquid.

[0056] The concentration ratio by the UF treatment using the UF membrane can be set arbitrarily. In other words, the UF treatment can be stopped when the outflow amount of the concentrated liquid reaches an arbitrary amount. It is preferable to concentrate 2 to 6 times. Concentrating 2 to 6 times means that the amount of the raw liquid (black liquor) becomes 1 / 2 to 1 / 6.

[0057] The temperature of the treatment liquid during UF treatment is not particularly limited. For example, it is preferably 20 to 80°C, and more preferably 20 to 70°C in consideration of the heat resistance of the UF membrane material. The pH value of the treatment liquid during UF treatment is preferably 2 to 11. The solid content concentration (w / w) of the black liquor during UF treatment is preferably 2 to 30%, more preferably 5 to 20%.

[0058] Examples of the modification treatment include chemically modified methods such as hydrolysis, alkylation, alkoxylation, sulfonation, sulfonate esterification, sulfomethylation, aminomethylation, desulfonation, alkalization, and condensation reaction with (poly)alkylene oxide; and a method of molecular weight fractionation of lignosulfonic acid by ultrafiltration. Of these, the chemically modified method is preferably one or more reactions selected from hydrolysis, alkoxylation, desulfonation and alkylation, and condensation reaction with (poly)alkylene oxide (e.g., WO 2021 / 066166).

[0059] [1.3 Soil improvement effect] The lignin sulfonic acid component has the effect of improving soil.

[0060] [soil] The target soil may be natural soil, and may be any of sand, fine soil, and clay. Examples of sand include coarse sand, fine sand, and gravel. Examples of soil include black soil (e.g., volcanic ash soil), diluvial soil (e.g., red-yellow soil, brown forest soil, red forest soil, red soil, yellow soil, dark red soil, gray plateau soil, gley plateau soil), and alluvial soil (e.g., brown lowland soil, gray lowland soil, and immature sand dune soil). The plasticity of the soil is not particularly limited, and may be, for example, heavy clay, clay soil, clay loam, loam, sandy loam, sand, gravel, and humus soil. Examples of uses of the soil include agricultural use (e.g., paddy field soil, field soil, forest soil, grassland soil (e.g., pasture, horse racing track)), civil engineering use, and green space use (e.g., turf grass and flower beds in gardens, parks, schools, facilities, etc.), and are not particularly limited.

[0061] Soil improvement includes, for example, increasing the amount of inorganic components (such as phosphorus atoms, iron atoms, etc.) in the soil, increasing the proliferation of microorganisms, dispersing pesticides, and promoting the formation of soil aggregates.

[0062] [1.4 Optional components] The soil conditioner may contain components (optional components) other than the lignosulfonic acid component as necessary. Examples of the optional components include soil conditioners other than the lignosulfonic acid component (e.g., sugars (e.g., glucose), inorganic components, polycarboxylic acids), excipients, colorants, preservatives, pH regulators, stabilizers, disintegrants, carriers, binders, pH adjusters, antifoamers, nonionic surfactants, cationic surfactants, amphoteric surfactants, and other optional components (formulation aids).

[0063] Examples of soil conditioners include inorganic components. Examples of inorganic components include inorganic salts of essential elements such as nitrogen, phosphorus, and potassium, and trace elements such as sulfur, calcium, magnesium, iron, manganese, zinc, boron, molybdenum, chlorine, iodine, and cobalt, oxides thereof, and inorganic salts containing these. Examples of inorganic salts include magnesium hydroxide, magnesium oxide, calcium carbonate (slaked lime), potassium nitrate, ammonium nitrate, ammonium chloride, sodium nitrate, potassium monohydrogen phosphate, sodium dihydrogen phosphate, potassium oxide, potassium chloride, potassium sulfate (sulfurized), ammonium sulfate (ammonium sulfate), magnesium sulfate, calcium sulfate, ferrous sulfate, ferrous sulfate, manganese sulfate, zinc sulfate, copper sulfate, sodium sulfate, calcium chloride, magnesium chloride, boric acid, molybdenum trioxide, sodium molybdate, potassium iodide, cobalt chloride, and calcium monophosphate, mixtures thereof (e.g., peroxycarbonate (a mixture of calcium monophosphate and calcium sulfate)), and hydrates thereof. The content of each optional component may be selected appropriately.

[0064] [1.5 Dosage form, manufacturing method] The form of the soil conditioner is not particularly limited, and may be, for example, powder, granule, granular, or liquid. Granules or granules can facilitate spreading. Liquids can facilitate mixing with functional components, and can stabilize the slurry after mixing. The plant growth promoter may be formulated together with the functional components, or may be formulated separately. The method for producing the soil conditioner can be appropriately selected according to the form.

[0065] [2. Improved soil composition] The soil to which the above-mentioned soil improver has been added can be used as an improved soil composition for various purposes such as agriculture and civil engineering, and is preferably used for agriculture, which is expected to increase crop yields and realize and popularize organic agriculture.

[0066] In the improved soil composition, the content of the soil improver of the present invention is, as the amount of the lignosulfonic acid component, usually 0.000001% by weight or more, preferably 0.00001% by weight or more, more preferably 0.00005% by weight or more, based on the weight of the soil. The upper limit is not particularly limited, but is usually 10% by weight or less.

[0067] The improved soil composition may contain other components other than the soil improver of the present invention and soil. The other components include soil improvers other than the plant growth promoter of the present invention, artificial soil (e.g., artificial soil such as rice husk charcoal, coconut fiber, vermiculite, perlite, peat moss, glass beads, rice husk, etc.; porous molded products such as foamed phenolic resin and rock wool; solidifying agents (e.g., agar or gellan gum), and combinations of two or more of these). The content of the other components may be selected appropriately.

[0068] [3. Method for preparing improved soil composition] The improved soil composition may be prepared by adding a soil improver to the soil. When mixing, a stirring device may be used as necessary. The soil improver and other components other than the soil may be added to the soil together with the soil improver, or may be added sequentially.

[0069] [4. Plant Production Method] The improved soil composition can be utilized for plant production.

[0070] [plant] Target plants include herbaceous plants and woody plants, such as Brassicaceae, Fabaceae, Cucurbitaceae, Solanaceae, Capsicum, Rosaceae, Malvaceae, Poaceae, Liliaceae, Amaryllidaceae, Asteraceae, Amaranthaceae, Umbelliferae, Zingiberaceae, Lamiaceae, Araceae, Convolvulaceae, Dioscoreaceae, and Nelumbaceae. Specific examples include leafy vegetables such as komatsuna, Chinese cabbage, onion, green onion, garlic, scallion, Chinese chives, lettuce, bok choy, cabbage, cauliflower, broccoli, Brussels sprouts, asparagus, lettuce, salad lettuce, celery, spinach, chrysanthemum, parsley, mitsuba, Japanese parsley, udo, myoga, butterbur, and shiso; fruit vegetables such as soybeans, edamame, broad beans, peas, cucumbers, eggplants, melons, corn, pumpkins, watermelons, tomatoes, bell peppers, strawberries, okra, and green beans; root vegetables such as carrots, turnips, radishes, burdocks, potatoes, taro, sweet potatoes, yams, ginger, and lotus roots; rice varieties (e.g., paddy rice, upland rice), wheat varieties (e.g., wheat, barley); and flowers. Examples of woody plants include the genus Cryptomeria japonica (e.g., Japanese cedar), the genus Chamaecyparis obtusifolia (e.g., Japanese cypress), the family Pinaceae (the genus Pinus (e.g., Japanese larch), the genus Larix (e.g., Japanese larch, Larch), the genus Abies (e.g., Abies sachalinensis)), the genus Eucalyptus (e.g., Eucalyptus), the genus Prunus (e.g., Cherry, Prunus mume, Prunus tomentosa), the genus Mangifera (e.g., Mango), the genus Acacia, the genus Myrica rubra, the genus Quercus acutissima (e.g., Quercus acutissima), the genus Vitis, the genus Malus, the genus Rosa, the genus Camellia (e.g., Tea), the genus Jacaranda (e.g., Jacaranda), the genus Crocodile (e.g., Avocado), the genus Pyrus (e.g., Pear), and the genus Sandalwood (e.g., Sandalwood (Sandalwood)). Among these, herbaceous plants are preferred, and plants of the family Brassicaceae and Fabaceae are more preferred.

[0071] The improved soil composition may be used throughout the entire growth period of a plant or for a part of the period. It may also be used for tissue culture such as cuttings and scions, as well as for breeding from seeds and seedlings.

[0072] In producing plants using the improved soil composition, the plant cultivation conditions (e.g., temperature, light intensity, amount of irrigation, humidity, carbon dioxide concentration, whether or not these are adjusted, seeding density, irrigation method, amount of irrigation, presence or absence of cultivation facilities / containers (e.g., planters, pots, bats, containers, cell trays)) are not particularly limited and can be selected appropriately. In addition, fertilizers may be added to the improved soil composition. Examples of fertilizers include components that can be a source of nutrients for plants, such as inorganic components, silver ions, antioxidants, carbon sources, vitamins, amino acids, and plant hormones. The form of the additive is not particularly limited and may be either a solid (e.g., powder, granules) or a liquid (e.g., liquid fertilizer). EXAMPLES

[0073] The present invention will now be described with reference to examples, which are not intended to limit the scope of the present invention.

[0074] The compositions of the main samples used in the examples are shown in Table 1.

[0075] [Table 1]

[0076] [Table 1 Footnotes] *1 "%" indicates the mass % relative to the dry weight of the sample.

[0077] *2 Phenolic hydroxyl group content The ionization difference spectrum was obtained by subtracting the absorption spectrum of a neutral solution containing the same concentration of lignin from the absorption spectrum of an alkaline solution containing the lignin sample, and the phenolic hydroxyl group (%) was calculated using the following formula, where Δαmax [L / (g cm)] represents the differential extinction coefficient (Junzo Nakano, ed., "Lignin Chemistry - Basics and Applications - Revised and Enlarged Edition," Uni Shuppan, May 25, 1990, p. 541). Phenolic hydroxyl group (%) = (17 × Δαmax) / 4100 × 100

[0078] *3 Carboxyl group content A 60 ml aqueous dispersion of 0.5% by mass of the sample was prepared, and a 0.1 M aqueous hydrochloric acid solution was added to adjust the pH to 2.5. Then, a 0.05 N aqueous sodium hydroxide solution was added dropwise, and the electrical conductivity was measured until the pH reached 11. The electrical conductivity was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid, where the change in electrical conductivity is gradual: Amount of carboxyl group [mmol / g sample] = a [ml] x 0.05 / mass of sample

[0079] *4 Reducing sugar content The content of reducing sugars in the lignin fertilizer was calculated by converting the values ​​measured by the Somogyi-Schaffer method into glucose content.

[0080] *5 Methoxyl (OCH3) group content The methoxyl group content of lignin was measured by the quantitative determination of methoxyl groups by the Viebock and Schwappach method (Lignin Chemical Research Methods, pp. 336-340, 1994, Uni Publishing).

[0081] *6 Total sulfur atom (S) content The S content was quantified by ICP atomic emission spectrometry.

[0082] *7 Sulfur oxide (SO3, SO4) content The SO3 and SO4 contents were quantified by ion chromatography.

[0083] *8 Sulfur atom (S) content of sulfonic groups The S content of the sulfonic group was calculated according to the following formula. Sulfonic acid content of sulfonic acid groups (mass%) = S content (mass%) - inorganic S content (mass%) In the formula, the mass % is the ratio of the S content to the solid content of lignosulfonic acid. The S content is a value measured by the method described above. The inorganic S content is the sum of the SO3 content and the SO4 content determined by the method described above.

[0084] *9 Weight average molecular weight (RI) Measurement was performed by gel permeation chromatography (GPC) under the following conditions. Measuring device: Tosoh Columns used: Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ Eluent: 0.05 mM sodium nitrate / acetonitrile 8 / 2 (v / v) Standard material: Polyethylene glycol (Tosoh or GL Science) Detector: Differential refractometer (Tosoh Corporation) Calibration curve; Polyethylene glycol standard

[0085] *10 Weight average molecular weight (UV) The measurement was carried out under the same conditions as for the weight average molecular weight by RI detection described above, except that a UV detector (280 nm, manufactured by Tosoh Corporation) was used as the detector.

[0086] *11 Ca content, Na content, Mg content Each metal ion (Ca 2+ , Na + , Mg 2+ ) were quantified by an inductively coupled plasma (ICP) method, and the quantitative results were converted into the Ca content, Na content, and Mg content (mass%), respectively.

[0087] <Production Example 1: Production of Sample 1> Wood (radiata pine) was treated with sulfite based on the sulfite cooking method to obtain an intermediate composition. In the sulfite treatment, a magnesium sulfite solution with a SO2 concentration of 4 g / 100 mL was used, and the temperature was 140°C, pH was 2, and the treatment time was 3 hours. Next, insoluble matter was filtered off, and the obtained filtrate was concentrated with a rotary evaporator until the solid content was 50%, to obtain intermediate composition A. Sample 1, which is a solidified composition, was obtained by spray drying.

[0088] <Production Example 2: Production of Sample 2> The intermediate composition A obtained in Production Example 1 was subjected to an alkali reaction (addition rate of calcium hydroxide solution: 9 wt.% (based on solid content), reaction temperature: 90°C, reaction time: 4 hours) and an oxidation reaction (treatment with oxygen, oxygen pressure: 200 kPa, reaction time: 2 hours), and the pH was adjusted to 7.0. This was spray-dried to obtain Sample 2, which is a solidified composition.

[0089] <Production Example 3: Production of Sample 3> Wood (radiata pine) was subjected to sulfite treatment based on the sulfite cooking method to obtain an intermediate composition. In the sulfite treatment, a solution of sodium sulfite with a SO2 concentration of 4 g / 100 mL was used, and the temperature was 140°C, pH was 2, and the treatment time was 3 hours. Next, insoluble matter was filtered off, and the obtained filtrate was adjusted to pH 5.0. This was subjected to ultrafiltration treatment using a polysulfone-based ultrafiltration membrane with a molecular weight cutoff of 20,000, and the concentrated liquid was spray-dried to obtain sample 3, which is a solidified composition.

[0090] <Test Example 1: Effect on microbial activity (Examples 1 to 3 and Comparative Examples 1 to 2)> [Carbon dioxide emissions] Volcanic ash soil (from Kitahon, Saitama Prefecture) and red-yellow soil (from Takashigahara, Aichi Prefecture) were mixed with each of the samples shown in Table 2 to prepare soil samples, which were then left to stand at 26.5°C and 50% humidity. The amount of carbon dioxide in the soil samples 30 days after preparation was measured using a carbon dioxide absorbent as follows. The soil sample and 8 mL of 0.1 N NaOH were placed in a beaker and incubated for 24 hours, after which 1 mL of 50% barium chloride was added to cause the carbon dioxide absorbed by the NaOH to precipitate as a white color. The remaining sodium hydroxide was titrated with 0.1 N hydrochloric acid using phenolphthalein as an indicator.

[0091] In addition, 50 g of a soil sample of volcanic ash soil was filled into a reflux device and 0.3 L of culture solution (composition: 1.2% lignin solution) was refluxed for 7 days, after which the number of colonies in the reflux solution and the refluxed soil were counted by the standard method using the dilution plate method (medium: albumin agar medium (egg albumin 0.25 g / L, glucose 1.0 g / L, K2HPO4 0.5 g / L, MgSO4 7H2O 0.2 g / L, Fe(SO4)31% 1 mL, agar 18.0 g / L, pH 6.8-7.0), culture period 26.5°C, 14 days) (N=1: Table 3).

[0092] [Table 2]

[0093] [Table 2 Footnotes] *1 Low molecular weight organic matter was measured using anthrone color-producing water-soluble substance (four times the amount of dry soil). Water-soluble: Leach with 4 times the amount of water as dry soil Acid solution: Leach with 4 times the amount of 0.5N-H2SO4 water relative to the dry soil. For both substances, 5 mL of sample (10-100 g as glucose) and 10 mL of anthrone reagent (0.2% anthrone 95% H2SO4 solution) were added to a test tube (diameter 23 mm) and allowed to cool. After cooling, colorimetric quantification was performed with a standard substance (glucose) at 625 nm. Organic acids: 40mL of the aqueous solution was neutralized with 1N-NaOH, then concentrated under reduced pressure to dryness, and 40mL of the acid solution was extracted with liquid ether for 48 hours. The extract was neutralized, concentrated under reduced pressure to dryness, and each was subjected to fractional quantification of organic acids by silica gel column chromatography. Fraction I represents butyric acid, propionic acid, valeric acid, etc., II represents acetic acid, III represents formic acid, pyruvic acid, and IV represents lactic acid, succinic acid, etc. The amount of fraction II is shown in Table 2 as the amount of organic acids. *2 Ash content was measured by incineration at 550°C in accordance with JIS P 8251:2003 "Paper, paperboard and pulp - Ash content test method". *3 Total CaO and MgO were measured by ICP and converted to oxides. *4 SO2 was measured by ion chromatography. *5 The carbon content (C) was measured using a total organic carbon meter after diluting the solution 6 times with 1 / 10-1 / 15M potassium phosphate monobasic solution to make it weakly acidic and then exposing it to N2 gas to remove dissolved carbon dioxide. *6 Dialyzed lignin is the dialysis product of sample 2. Dialysis was performed using a dialysis membrane (BIOTECH CE TRIAL KIT, manufactured by Funakoshi Co., Ltd.) under conditions for 3.5-5.0 kDa fractionation. *7 Glucose used was D-(+)-Glucose manufactured by Fujifilm Wako Pure Chemical Industries. Reducing sugars and sulfur were quantified using the methods described in the footnotes of Table 1.

[0094] [Table 3]

[0095] The soil samples of Examples 1 to 3 (both volcanic ash soil and red-yellow soil) using samples containing lignosulfonic acid generated more carbon dioxide than Comparative Examples 1 and 2 (Table 3), suggesting that the addition of lignosulfonic acid improved the growth environment for microorganisms. Furthermore, in Example 1, the number of colonies in the reflux liquid and reflux soil was greater than in Comparative Example 1 where no additive was used, suggesting that the growth environment for microorganisms such as bacteria was improved and the soil was activated (Table 3).

[0096] <Test Example 2: Effect on the divalent iron ion content in paddy field soil (Examples 4 to 5 and Comparative Example 3)> The samples shown in Table 4 were added to 7.2 g of air-dried fine soil (paddy soil from Nagano Prefecture) of 2 mm or less in the amount shown in Table 4, collected in a 20 mL (±5 g) syringe, and further collected 10 g of water and flooded (to reproduce the paddy field condition), and incubated in a thermostatic chamber at 26.5 ° C for 35 days. The ratio of air-dried fine soil to water was adjusted to (1:2). Samples on the 0th, 2nd, 7th, 14th, 21st, and 35th days from the start of incubation were extracted using 1 M sodium acetate-hydrochloric acid buffer at pH 2.8, and colorimetric quantification of ferrous ion (FeII) was performed using the orthophenanthroline method. That is, the amount of ferrous ion was calculated using the calibration curve created by the following method (N = 1: Table 5). 1. 0.0, 0.2, 0.4, 0.6, and 0.8 mL of iron standard solution (50 μg / mL) was accurately dispensed into five 10 mL measuring flasks using a measuring pipette. 2. 0.4 mL of 6 mol / L hydrochloric acid was added, followed by addition of 0.25 mL of hydroxylammonium chloride solution (100 g / L) and shaking. 3. 0.5 mL of phenanthroline solution (1 g / L) and 1 mL of ammonium acetate solution (500 g / L) were added, and then ion-exchanged water was added to make exactly 10 mL. 4. The absorbance at 510 nm was measured using ion-exchanged water as a reference.

[0097] [Table 4]

[0098] [Table 5]

[0099] Examples 4 and 5, which contained lignosulfonic acid, had a higher content of divalent iron ions than Comparative Example 3, which contained no additive, and Example 5 in particular showed a significantly higher value (Table 5).

[0100] <Test Example 3: Effect on phosphoric acid permeation amount (Examples 6 to 7 and Comparative Example 4)> Air-dried soils (alluvial volcanic ash unfertilized soil, heavy clay soil, alluvial red forest soil) were passed through a 2 mm sieve, and the portion that passed through was used as the sample soil (Table 6). 50 g of the sample soil was weighed out into a 500 mL beaker, 225 mL of the P-containing aqueous solution described below was added, stirred well, and then left at room temperature for 24 hours. Water was added to this to obtain a paddy water sample with a total volume of 500 mL while still containing the soil. This was filtered through dry filter paper (Toyo Filter Paper No. 5A). A portion of the filtrate was placed in an aluminum measuring dish and evaporated to dryness, and the count number (CPM: Counters Per Minute) was measured using a GM counter and compared with the count number for standard P to calculate the total P value in the paddy water sample. The phosphate absorption rate is the ratio of P adsorbed by the soil to the total P added. 32 The results are expressed as a percentage of the total (N=1: Table 7). 32 is manufactured by The Radiochemical Centre, UK, in orthophosphate solution (pH 2-3), radiochemical purity >99%. [P-containing aqueous solution] P2O5 550mg (NaH2PO4) N 50mg (NH4Cl) K 50mg (KCl) The lignin samples were dissolved in a P-containing aqueous solution at 0.0001% (=0.05 mg) and 0.001% (=0.5 mg) of the soil.

[0101] [Table 6]

[0102] [Table 7]

[0103] In Examples 6 and 7, in which lignosulfonic acid was used, the amount of residual phosphoric acid in the paddy water was greater in each soil than in Comparative Example 4, in which no lignosulfonic acid was added (Table 7).

[0104] <Test Example 4: Calcium carbonate dispersion test (B-type viscosity test) (Example 8, Comparative Examples 5 to 6)> The effect of calcium carbonate, which is used as an extender in pesticides, on the dispersibility was evaluated. 172.44 g of calcium carbonate (water content 30%) was mixed with 37.56 g of water and each dispersant shown in Table 8 and stirred to prepare a slurry. The slurry concentration of water and calcium carbonate was 57%, and the amount of dispersant added (solid content addition rate) was 0.05 or 0.1% of the total amount of the slurry. Stirring was performed with a Homo Disper at 3000 rpm for 2 minutes. The B-type viscosity of the slurry after stirring was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) at 20°C, 60 rpm, No. 3 rotor or No. 2 rotor, without guard (Table 8).

[0105] [Table 8]

[0106] Example 8, which used sample 3, had a lower viscosity than Comparative Example 5, which used water only. This shows that the soil conditioner of the present invention exhibits good dispersibility in soil and can also increase the dispersibility of other components added at the same time, and that the improved compatibility with the soil can improve effects such as aggregate formation.

[0107] <Test Example 5: Crumbling effect (Examples 9 to 13 and Comparative Examples 7 to 8)> 50-100g of each test soil (Table 9) was placed in a petri dish (90mm x 20mm) or beaker (200cc), and the sample was applied in the amount shown in Tables 9 and 10 (% by weight: relative to bone dry soil). After thorough mixing, 60% of the maximum amount of water was added and incubated at 30°C for 7 days. After incubation, the soil was air-dried for 5-7 days to obtain samples for aggregate analysis (N=3). Aggregate analysis was performed in the usual manner using the underwater sieving method. The analysis results were expressed as the degree of aggregate formation of particles of 0.25mm or less, and the aggregate formation ability was compared. The degree of aggregate formation was calculated using the following formula. Aggregation degree (%) = {(secondary particles - primary particles) / absolute dry amount of test soil} x 100

[0108] [Table 9]

[0109] [Table 10]

[0110] The lignin sulfonic acid component had a higher agglomeration effect than azumin, and the agglomeration effect tended to increase depending on the amount added.

Claims

1. A soil conditioner comprising lignosulfonic acid in which the proportion of the sulfur atom content derived from sulfonic groups in the sulfur atom content contained in lignosulfonic acid is 0.5 or more, the calcium atom content is 0.001% by weight or more, the sodium atom content is 0.3% by weight or more, and the magnesium atom content is 0.05% by weight or more.

2. Regarding the lignosulfonic acid, the sulfur atom content is 2.0% by weight or more, the phenolic hydroxyl group content is 0.5 to 5.0% by weight, and the reducing sugar content is 35% by weight or less, The agent according to claim 1, satisfying at least any one of the above.

3. The agent according to claim 1 or 2, wherein the carboxyl group content of the lignosulfonic acid is 0.3 to 4.0 mmol / g.

4. The agent according to claim 1 or 2, wherein the weight average molecular weight (RI) of the lignosulfonic acid is 3,000 or more.

5. The agent according to claim 1 or 2, wherein the lignosulfonic acid has a substituent derived from (poly)alkylene oxide.

6. The agent according to claim 1 or 2, wherein the soil is agricultural soil.

7. An improved soil composition comprising the agent according to claim 1 or 2 and soil.

8. A method for preparing improved soil, comprising adding the agent according to claim 1 or 2 to the soil.

9. A method for producing a plant, using the improved soil composition according to claim 7 to produce the plant.