Method for preparing soil for plant cultivation, soil preparation agent, plant growth promoter, and method for growing plants

Abstract

To provide a soil preparation method and a soil preparation agent capable of growing plants by preventing the outflow of water and nutrients even in a dry environment having low water and nutrient holding capacity, without adding a salt of a metal such as aluminum to the soil.SOLUTION: There are provided a method for preparing a soil for plant cultivation, a soil preparation agent for plant cultivation, a plant growth promoter, and method for growing plants using the same, characterized by adding a fertilizer and microfibril cellulose to the soil.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for preparing soil for plant cultivation. More specifically, the present invention relates to a method for preparing soil for plant cultivation and a soil preparation agent, which are characterized by adding fertilizer and microfibrillar cellulose to the soil.

Background Art

[0002] Good soil conditions for plant growth include good air permeability and drainage, and at the same time, appropriate water retention and fertilizer retention capabilities for retaining moisture and fertilizer. In recent years, from the perspective of food crisis and the like, attempts have been made to improve the soil in order to improve the production efficiency of agricultural crops even in lands with low water retention and fertilizer retention that were previously considered unsuitable for producing agricultural crops.

[0003] On the other hand, microfibrillar cellulose obtained by finely decomposing plant fibers includes microfibrillar cellulose and cellulose nanofibers, and is known to be microfibers with a fiber diameter of about 2 nm to several tens of μm. In recent years, since microfibrillar cellulose is a natural-derived material, it is expected to be utilized as a biodegradable resource.

[0004] As a method for improving the water retention of soil with a cellulose-based substance, a method has been reported in which a gel-like substance composed of an aluminum metal salt of carboxymethyl cellulose is placed in the soil, and as a result of the biodegradation of the gel-like substance by bacteria in the soil, the cross-linked structure of the gel collapses, and the water contained in the gel is gradually released over a long period of time (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As a result of investigations by the present inventors, it has been found that when an aluminum metal salt is added to soil as in Patent Document 1, aluminum ions react with water and the soil tends to become acidic. In particular, a problem has been that common crops are likely to be damaged in acidic soil.

[0007] An object of the present invention is to provide a method for preparing soil and a soil conditioner that enable plant growth by preventing the outflow of moisture and nutrients even in a dry environment with low moisture and nutrient retention capacity without adding a metal salt such as aluminum to the soil.

Means for Solving the Problems

[0008] As a result of intensive investigations by the present inventors, by adding fertilizer and microfibrillated cellulose to the soil, it is possible to improve the retention capacity of fertilizer components by exerting the effect of suppressing penetration of the soil surface with microfibrillated cellulose even in an environment with low moisture and nutrient retention capacity without adding a metal salt such as aluminum to the soil, and a method for preparing soil that enables plant growth has been found. The present invention includes, but is not limited to, the following. (1) A method for preparing soil for plant cultivation, characterized by adding fertilizer and microfibrillated cellulose to the soil. (2) The method for preparing soil for plant cultivation according to (1), wherein the added weight of the microfibrillated cellulose is 0.01 to 5 parts by weight with respect to 100 parts by weight (dry weight) of the soil. (3) The method for preparing soil for plant cultivation according to (1) or (2), characterized in that the microfibrillated cellulose contains a carboxymethyl group. (4) The method for preparing soil for plant cultivation according to (3), characterized in that the degree of substitution of the carboxymethyl group in the microfibrillated cellulose is 0.01 to 0.50. (5) The method for preparing soil for plant cultivation according to any one of (1) to (2), characterized in that the microfibrillated cellulose contains a carboxyl group. (6) The method for preparing a soil for plant cultivation according to (5), characterized in that the amount of carboxyl groups in the microfibrillated cellulose is 1.0 to 2.0 mol / g. (7) A soil preparation agent for plant cultivation, characterized by containing a fertilizer and microfibrillated cellulose. (8) A method for producing a plant, characterized by using a soil preparation agent for plant cultivation, which contains a fertilizer and microfibrillated cellulose. (9) A plant growth promoter, characterized by containing a fertilizer and microfibrillated cellulose. [[Effect of the Invention]]

[0009] In the method for preparing soil and the soil preparation agent of the present invention configured as described above, microfibrillated cellulose, which has high water retention capacity by itself without adding a metal salt such as aluminum to the soil, supplies the water it holds to the soil, and can retain moisture and nutrients even in soil with low moisture and nutrient retention capacity. Further, after mixing a soil conditioner mixed with a fertilizer and microfibrillated cellulose into the soil, the microfibrillated cellulose itself is gradually decomposed and reduced to the soil, so that it is possible to prevent residue in the soil. [[Brief Description of the Drawings]]

[0010]

Figure 1

[0011] The present invention is a method for preparing soil, and includes a method for preparing a soil for plant cultivation and a method for producing a plant using the soil preparation agent. Hereinafter, the present invention will be described in detail. In this specification, the notation "AA~BB" (where AA and BB each represent a number) indicates AA or more and BB or less.

[0012] (Soil) Soil is classified into gravel (particle size 2 mm or more), coarse sand (particle size 0.2 mm to 2 mm), fine sand (particle size 0.02 mm to 0.2 mm), silt (particle size 0.002 mm to 0.02 mm), and clay (particle size 0.002 mm or less) according to the size of soil particles. The soil to which the present invention is applied is not particularly limited, but soil with low water retention and low fertilizer retention is particularly preferred. Examples of soil with low water retention and low fertilizer retention include sandy soil, loamy sandy soil, sandy loam, loam, silty loam, and artificial soil (rice husk charcoal, coconut fiber, vermiculite, perlite, peat moss, glass beads, etc.) with a clay content of 15% or less.

[0013] (Soil moisture) Soil is composed of three phases: soil particles (solid), water (liquid), and air (gas). Soil moisture can be expressed as the moisture content (%) as a percentage of the weight of water in the wet soil. The soil with low water retention to which the present invention can be particularly preferably applied is not particularly limited, but the moisture content is 30% or less.

[0014] (Target plant) The present invention can be applied to any plant, and usually, any annual herbaceous plant, perennial herbaceous plant, and woody plant can be used without particular limitation as long as it is a variety commonly used as a cultivated variety, but it is particularly preferably a plant for agricultural and horticultural use. The target plant is preferably a herbaceous plant, and more preferably a herbaceous plant for agricultural and horticultural use. Herbaceous plants include annual plants, biennial plants, or perennial plants.

[0015] The herbaceous plant is preferably at least one plant selected from the group consisting of Gramineae cereals, vegetables, and flowers. Such plants include, for example, Gramineae, Brassicaceae (e.g., radish (spring radish), Chinese cabbage, cabbage, daikon radish, turnip, Komatsuna, broccoli, spinach, and stock, etc.), Solanaceae (e.g., tomato, eggplant, pepper, paprika, capsicum, petunia, Physalis alkekengi var. franchetii, and potato, etc.), Fabaceae (e.g., kidney bean, broad bean, azuki bean, soybean, green bean, and pea, etc.), Cucurbitaceae (e.g., cucumber, pumpkin, watermelon, melon, bottle gourd, loofah, and zucchini, etc.), Apiaceae, Alliaceae, Liliaceae, Asteraceae (e.g., marigold, burdock, shungiku, lettuce, chrysanthemum, gerbera, and cineraria, etc.), Rosaceae (e.g., rose, strawberry, apple, pear, European pear, peach, and nectarine, etc.), Convolvulaceae, Iridaceae, etc. are exemplified. Further, the present invention can be used at any stage of the plant growth process, and it may be cultivated from seeds or from seedlings.

[0016] (Fertilization) The fertilizer that can be used in the present invention is not particularly limited, and it may be a quick-acting fertilizer or a slow-acting fertilizer, but an inorganic fertilizer or an organic fertilizer is more preferable, and a chemical fertilizer is even more preferable.

[0017] The components contained in the fertilizer are not particularly limited, and examples include components that can be a source of plant nutrients such as inorganic components, silver ions, antioxidants, carbon sources, vitamins, amino acids, and plant hormones. The form of the fertilizer is not particularly limited, and it may be either a solid (e.g., powder, granule) or a liquid (e.g., liquid fertilizer).

[0018] Examples of inorganic components include elements such as nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, iron, manganese, zinc, boron, molybdenum, chlorine, iodine, cobalt, etc., and inorganic salts containing these. Examples of the inorganic salts include potassium nitrate, ammonium nitrate, ammonium chloride, sodium nitrate, potassium monohydrogen phosphate, disodium hydrogen phosphate, potassium chloride, potassium sulfate, ammonium sulfate, magnesium sulfate, ferrous sulfate, ferric sulfate, manganese sulfate, zinc sulfate, copper sulfate, sodium sulfate, calcium chloride, magnesium chloride, boric acid, molybdenum trioxide, sodium molybdate, potassium iodide, cobalt chloride, etc., and hydrates thereof.

[0019] Examples of antioxidants include, for example, ascorbic acid and sulfite, and ascorbic acid is preferred. Since ascorbic acid has low residual property in the medium, environmental pollution can be suppressed.

[0020] Examples of carbon sources include compounds such as carbohydrates and their derivatives such as sucrose; organic acids such as fatty acids; primary alcohols such as ethanol, etc.

[0021] Examples of vitamins include, for example, biotin, thiamine (vitamin B1), pyridoxine (vitamin B4), pyridoxal, pyridoxamine, calcium pantothenate, inositol, nicotinic acid, nicotinamide, and riboflavin (vitamin B2).

[0022] Examples of amino acids include, for example, glycine, alanine, glutamic acid, cysteine, phenylalanine, lysine, etc.

[0023] Among fertilizers, the fertilizer that can be used in the present invention is particularly preferably a liquid fertilizer, and a commercially available liquid fertilizer may be used. Specific examples of commercially available liquid fertilizers include urea complex liquid fertilizer, urea complex liquid fertilizer containing boron, manganese, and magnesia, ammonium nitrate-based complex liquid fertilizer, calcium nitrate-based liquid fertilizer, liquid fertilizer containing organic matter, ammonium phosphate liquid fertilizer, powder liquid fertilizer, nitrogen-free liquid fertilizer, liquid micronutrient compound fertilizer, etc.

[0024] The lower limit of the content of the fertilizer component in the liquid fertilizer is not particularly limited, but is preferably 0.001% by mass or more, and more preferably 0.005% by mass or more. When the fertilizer component is within the above range, the effect of the liquid fertilizer can be exhibited favorably. Further, the upper limit of the content of the fertilizer component in the liquid fertilizer is not particularly limited, but is preferably 25% by mass or less, and more preferably 20% by mass or less.

[0025] (Microfibrillated cellulose) "Microfibrillated cellulose" is fine fiber obtained by defibrating cellulose fiber. Hereinafter, "microfibrillated cellulose" may be abbreviated as "MFC".

[0026] The type of cellulose serving as a raw material for MFC is not particularly limited. For example, cellulose derived from plants (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animals (e.g., tunicates), algae, microorganisms (e.g., acetic acid bacteria (Acetobacter)), microbial products, etc. can be used. Preferably, it is cellulose fiber derived from plants or microorganisms, and more preferably cellulose fiber derived from plants. MFC may or may not be chemically modified. Chemical modification is preferable in that fibrillation of the fiber is more likely to proceed.

[0027] By introducing a modifying group to the above cellulose raw material, modified cellulose fibers can be obtained. The method for introducing the modifying group is not particularly limited. For example, an anionic group can be introduced into the pyranose ring of cellulose by an oxidation or substitution reaction. Specifically, examples include a reaction of oxidizing the hydroxyl group of the pyranose ring to convert it into a carboxyl group, and a reaction of introducing a carboxymethyl group, a phosphate ester group, or a phosphite ester group into the pyranose ring by a substitution reaction. Among these, the reaction of oxidizing the hydroxyl group of the pyranose ring to convert it into a carboxyl group (oxidation) and the reaction of introducing a carboxymethyl group into the pyranose ring by a substitution reaction (carboxymethylation) are preferred.

[0028] (Carboxymethylation) As an example of chemical modification, carboxymethylation can be mentioned. Carboxymethylated cellulose fibers, which are an example of anionic modified cellulose fibers, may be obtained by carboxymethylating the above cellulose raw material by a known method, or may be commercially available products. In either case, those having a carboxymethyl substitution degree of 0.01 to 0.50 per anhydroglucose unit of cellulose are preferred, 0.02 to 0.40 are more preferred, and 0.10 to 0.30 are even more preferred. When the carboxymethyl substitution degree exceeds 0.50, it will dissolve in a medium such as water and it will be impossible to maintain a fibrous shape. By maintaining a fibrous form, it is difficult to flow out of the system even when it rains, and it can have a high water retention capacity and fertilizer retention capacity.

[0029] The carboxymethyl substitution degree of carboxymethylated cellulose fibers can be measured by the following method:

[0030] Weigh accurately about 2.0 g of carboxymethylated cellulose fiber (dry basis) and place it in a 300 mL Erlenmeyer flask with a stopper. Add 100 mL of nitric acid methanol (a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol), shake for 3 hours to convert carboxymethylated cellulose in salt form (CM cellulose) to hydrogen form CM cellulose. Weigh accurately 1.5 g - 2.0 g of hydrogen form CM cellulose (dry basis) and place it in a 300 mL Erlenmeyer flask with a stopper. Moisten the hydrogen form CM cellulose with 15 mL of 80% by mass methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, back-titrate the excess NaOH with 0.1 N H 2 SO 4 Calculate the degree of carboxymethyl substitution (DS) using the following formula: A = [(100 × F’ - (0.1 N H 2 SO 4 )(mL) × F) × 0.1] / (dry mass of hydrogen form CM cellulose (g)) DS = 0.162 × A / (1 - 0.058 × A) A: Amount of 1 N NaOH (mL) required for neutralization of 1 g of hydrogen form CM cellulose F: Factor of 0.1 N H 2 SO 4 of F’: Factor of 0.1 N NaOH.

[0031] As an example of a method for producing carboxymethylated cellulose fiber, the following method can be cited: To the cellulose raw material, 3 to 20 times by weight of water and / or lower alcohol as a solvent are added, specifically, water, methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butyl alcohol, isobutyl alcohol, tertiary butanol, etc., alone or as a mixed medium of two or more. When mixing a lower alcohol with the solvent, the mixing ratio of the lower alcohol is preferably 60 to 95% by mass. Here, as the mercerizing agent, 0.5 to 20 times the molar amount of an alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide, per anhydroglucose residue of the cellulose raw material is added. The cellulose raw material, the solvent, and the mercerizing agent are mixed, and a mercerization treatment is carried out at a reaction temperature of 0 to 70°C, preferably 10 to 60°C, and a reaction time of 15 minutes to 8 hours, preferably 30 minutes to 7 hours. Then, a carboxymethylating agent, such as monochloroacetic acid or its salt, etc., is added in an amount of 0.05 to 10.0 times the molar amount per glucose residue, and an etherification reaction is carried out at a reaction temperature of 30 to 90°C, preferably 40 to 80°C, and a reaction time of 30 minutes to 10 hours, preferably 1 hour to 4 hours.

[0032] (Oxidation (carboxylation)) As another example of chemical modification, oxidation (carboxylation) can be mentioned. By the oxidation treatment, usually, at least one of the hydroxyl groups originally possessed by cellulose is modified to a carboxyl group, and preferably, at least one of the hydroxyl groups bonded to the carbon atom at the 6-position of the glucopyranose ring is modified to a carboxyl group.

[0033] The oxidation method in the oxidation treatment is not particularly limited. For example, a method of oxidizing a cellulose-based raw material in water using an oxidizing agent in the presence of an N-oxyl compound and at least one of a bromide and an iodide can be mentioned. According to this method, the carbon atom having a primary hydroxyl group bonded to the carbon atom at the 6-position of the glucopyranose ring on the cellulose surface is selectively oxidized, and a group selected from the group consisting of an aldehyde group, a carboxyl group, and a carboxylate group is generated. The concentration of the cellulose-based raw material during the reaction is preferably 5% by mass or less, but is not particularly limited.

[0034] An N-oxyl compound refers to a compound capable of generating a nitroxyl radical. Examples of the nitroxyl radical include 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) and its derivatives (e.g., 4-hydroxy TEMPO). As the N-oxyl compound, any compound can be used as long as it promotes the target oxidation reaction.

[0035] The amount of the N-oxyl compound used may be any amount that catalyzes the oxidation reaction of the cellulose serving as the raw material. For example, for 1 g of absolutely dry cellulose, 0.001 mmol or more is preferable, and 0.01 mmol or more is more preferable. The upper limit is preferably 10 mmol or less, more preferably 1 mmol or less, and even more preferably 0.1 mmol or less. Therefore, the amount of the N-oxyl compound used is preferably 0.001 to 10 mmol, more preferably 0.01 to 1 mmol, and even more preferably 0.01 to 0.1 mmol with respect to 1 g of absolutely dry cellulose. The amount of the N-oxyl compound used with respect to the reaction system is usually about 0.1 to 4 mmol / L.

[0036] A bromide is a compound containing bromine, and examples thereof include an alkali metal bromide that dissociates and ionizes in water. An iodide is a compound containing iodine, and examples thereof include an alkali metal iodide. The amount of the bromide or iodide used is not particularly limited and can be selected within a range capable of promoting the oxidation reaction. The total amount of the bromide and iodide is preferably 0.1 mmol or more, more preferably 0.5 mmol or more with respect to 1 g of absolutely dry cellulose. The upper limit of the amount is preferably 100 mmol or less, more preferably 10 mmol or less, and even more preferably 5 mmol or less. Therefore, the total amount of the bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol with respect to 1 g of absolutely dry cellulose.

[0037] The oxidizing agent is not particularly limited, and examples thereof include halogen, hypohalous acid, halous acid, perhalic acid, salts thereof, halogen oxides, and peroxides. Among them, hypohalous acid or its salt is preferable, hypochlorous acid or its salt is more preferable, and sodium hypochlorite is even more preferable because of its low cost and low environmental impact. The amount of the oxidizing agent used is preferably 0.5 mmol or more, more preferably 1 mmol or more, and even more preferably 3 mmol or more per 1 g of cellulose on an absolutely dry basis. The upper limit of the amount is preferably 500 mmol or less, more preferably 50 mmol or less, even more preferably 25 mmol or less, and even more preferably 10 mmol or less. Therefore, the amount of the oxidizing agent used is preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, even more preferably 1 to 25 mmol, and even more preferably 3 to 10 mmol per 1 g of cellulose on an absolutely dry basis. When an N-oxyl compound is used, the amount of the oxidizing agent used is preferably 1 mol or more per 1 mol of the N-oxyl compound, and the upper limit is preferably 400 mol or less. Therefore, the amount of the oxidizing agent used per 1 mol of the N-oxyl compound is preferably 1 to 400 mol.

[0038] The conditions such as pH and temperature during the oxidation reaction are not particularly limited. Generally, the oxidation reaction proceeds efficiently even under relatively mild conditions. The reaction temperature is preferably 4°C or higher, more preferably 15°C or higher. The upper limit of the temperature is preferably 40°C or lower, more preferably 30°C or lower. Therefore, the reaction temperature is preferably 4 to 40°C, and may be about 15 to 30°C, that is, room temperature. The pH of the reaction solution is preferably 8 or higher, more preferably 9 or higher, or 10 or higher. The upper limit of the pH is preferably 12 or lower, more preferably 11 or lower. Therefore, the pH of the reaction solution is preferably 8 to 12, more preferably 9 to 11, or about 10 to 11. Usually, carboxyl groups are generated in the cellulose as the oxidation reaction proceeds, so the pH of the reaction solution tends to decrease. Therefore, in order to efficiently proceed the oxidation reaction, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution within the above range. The reaction medium during oxidation is preferably water for reasons such as ease of handling and difficulty in causing side reactions. The reaction time in oxidation can be appropriately set according to the progress of oxidation, usually 0.5 hours or more, and the upper limit is usually 6 hours or less, preferably 4 hours or less. Therefore, the reaction time in oxidation is usually about 0.5 to 6 hours, preferably about 0.5 to 4 hours.

[0039] The oxidation may be carried out in two or more stages. For example, the oxidized cellulose obtained by filtration after the completion of the first-stage reaction can be oxidized again under the same or different reaction conditions, so that it can be efficiently oxidized without being inhibited by the reaction of by-produced sodium chloride in the first-stage reaction.

[0040] Another example of oxidation is ozone oxidation. By this oxidation reaction, at least the hydroxyl groups at the 2nd and 6th positions of the glucopyranose ring constituting the cellulose are oxidized, and the decomposition of the cellulose chain occurs.

[0041] The ozone treatment is usually carried out by bringing a gas containing ozone into contact with a cellulose-based raw material. The ozone concentration in the gas is preferably 50 g / m 3 or higher. The upper limit is 250 g / m 3The following is preferable: 220 g / m 3 The following is more preferable. Therefore, the ozone concentration in the gas is preferably 50 - 250 g / m 3 and more preferably 50 - 220 g / m 3 The ozone addition amount is preferably 0.1 part by mass or more, and more preferably 5 parts by mass or more, based on 100 parts by mass of the solid content of the cellulosic raw material. The upper limit of the ozone addition amount is usually 30 parts by mass or less. Therefore, the ozone addition amount is preferably 0.1 - 30 parts by mass, and more preferably 5 - 30 parts by mass, based on 100 parts by mass of the solid content of the cellulosic raw material. The ozone treatment temperature is usually 0°C or higher, preferably 20°C or higher, and the upper limit is usually 50°C or lower. Therefore, the ozone treatment temperature is preferably 0 - 50°C, and more preferably 20 - 50°C. The ozone treatment time is usually 1 minute or more, preferably 30 minutes or more, and the upper limit is usually 360 minutes or less. Therefore, the ozone treatment time is usually about 1 - 360 minutes, and preferably about 30 - 360 minutes. When the conditions of the ozone treatment are within the above ranges, it is possible to prevent the cellulose from being excessively oxidized and decomposed, and the yield of the oxidized cellulose can be good.

[0042] Further post-oxidation treatment using an oxidizing agent may be performed on the ozone-treated cellulose. The oxidizing agent used for the post-oxidation treatment is not particularly limited, and examples include chlorine-based compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. As a method of the post-oxidation treatment, for example, a method of dissolving an oxidizing agent in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution and immersing the cellulosic raw material in the oxidizing agent solution can be mentioned. The amounts of carboxyl groups, carboxylate groups, and aldehyde groups contained in the oxidized cellulose can be adjusted by controlling oxidation conditions such as the addition amount of the oxidizing agent and the reaction time.

[0043] The amount of carboxyl groups (total amount of carboxyl groups and carboxylate groups) in oxidized MFC is usually 1.0 mmol / g or more, preferably 1.1 mmol / g or more, more preferably 1.2 mmol / g or more, still more preferably 1.3 mmol / g or more, based on the absolute dry mass of oxidized MFC. The upper limit is usually 2.0 mmol / g or less, preferably 1.8 mmol / g or less, more preferably 1.6 mmol / g or less, still more preferably 1.5 mmol / g or less. Therefore, it is usually 1.0 to 2.0 mmol / g, preferably 1.1 to 1.8 mmol / g, more preferably 1.2 to 1.6 mmol / g, still more preferably 1.3 to 1.5 mmol / g. The amount of carboxyl groups in oxidized MFC can be adjusted by controlling reaction conditions such as the addition amount of the oxidizing agent and the reaction time. The amount of carboxyl groups can be measured by the following method: Prepare 60 ml of a 0.5 mass% slurry (aqueous dispersion) of oxidized MFC, add 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.4, then dropwise add 0.05 N sodium hydroxide aqueous solution and measure the electrical conductivity until the pH reaches 11. Calculate 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 gentle: Amount of carboxyl groups [mmol / g of oxidized CNF] = a [ml] × 0.05 / mass of oxidized CNF [g].

[0044] (Esterification) In the present invention, when using esterified cellulose as the chemically modified cellulose, examples of the method include mixing a powder or aqueous solution of Compound A below with the cellulose-based raw material, and adding an aqueous solution of Compound A to a slurry of the cellulose-based raw material.

[0045] Compound A includes phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, or esters thereof. These may take the form of salts. Among these, compounds having a phosphate group are preferred because they are low-cost, easy to handle, and can introduce a phosphate group into the cellulose of pulp fibers to improve fibrillation efficiency. Examples of compounds having a phosphate group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium metaphosphate, etc. These can be used alone or in combination of two or more to introduce a phosphate group. Among these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred from the viewpoints of high efficiency of phosphate group introduction, easy fibrillation in the following fibrillation step, and easy industrial application. In particular, sodium dihydrogen phosphate and disodium hydrogen phosphate are preferred. Also, since the uniformity of the reaction is enhanced and the efficiency of phosphate group introduction is increased, it is desirable to use the phosphoric acid-based compound as an aqueous solution. The pH of the aqueous solution of the phosphoric acid-based compound is preferably 7 or less because the efficiency of phosphate group introduction is increased, but pH 3 to 7 is preferred from the viewpoint of suppressing hydrolysis of pulp fibers.

[0046] If an example of a method for producing phosphorylated cellulose is to be given, the following method can be mentioned. To a suspension of a cellulose-based raw material with a solid content concentration of 0.1 to 10% by weight, Compound A is added while stirring to introduce a phosphate group into the cellulose. When the cellulose-based raw material is 100 parts by weight, the addition amount of Compound A is preferably 0.2 to 500 parts by weight, more preferably 1 to 400 parts by weight, in terms of the amount of phosphorus element. If the ratio of Compound A is at least the above lower limit, the yield of microfibrillated cellulose can be further improved. However, even if it exceeds the above upper limit, the effect of improving the yield levels off and only Compound A is used wastefully.

[0047] At this time, in addition to the cellulose raw material and Compound A, a powder or aqueous solution of Compound B may be mixed. Compound B is not particularly limited, but a nitrogen-containing compound showing basicity is preferable. The definition of the "basicity" is the case where the aqueous solution exhibits a peach to red color in the presence of a phenolphthalein indicator, and / or the case where the pH of the aqueous solution is greater than 7. The nitrogen-containing compound showing basicity used in the present invention is not particularly limited as long as the effects of the present invention are exhibited, but a compound having an amino group is preferable. For example, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, etc. can be mentioned, but it is not particularly limited. Among these, urea which is low-cost and easy to handle is preferable. The addition amount of Compound B is preferably 2 to 1000 parts by weight, more preferably 100 to 700 parts by weight. The reaction temperature is preferably 0 to 95°C, more preferably 30 to 90°C. The reaction time is not particularly limited, but is about 1 to 600 minutes, more preferably 30 to 480 minutes. When the conditions of the esterification reaction are within these ranges, it is possible to prevent the cellulose from being excessively esterified and becoming easily soluble, and the yield of the phosphoric acid esterified cellulose becomes good. After dehydrating the obtained phosphoric acid esterified cellulose suspension, from the viewpoint of suppressing the hydrolysis of cellulose, it is preferable to perform heat treatment at 100 to 170°C. Further, while water is contained during the heat treatment, it is preferable to heat at 130°C or lower, preferably 110°C or lower, and after removing the water, perform heat treatment at 100 to 170°C.

[0048] The degree of substitution of phosphate groups per glucose unit of the phosphorylated cellulose is preferably from 0.001 to 0.40. By introducing phosphate group substituents into cellulose, the celluloses repel each other electrically. Therefore, the cellulose into which phosphate groups are introduced can be easily defibrated into microfibril form. Note that if the degree of substitution of phosphate groups per glucose unit is less than 0.001, it cannot be sufficiently defibrated. On the other hand, if the degree of substitution of phosphate groups per glucose unit is greater than 0.40, it swells or dissolves, and thus may not be obtained as microfibril cellulose. In order to perform defibrillation efficiently, the phosphorylated cellulose-based raw material obtained above is preferably washed by boiling and then washing with cold water.

[0049] (Cellulose fiber) As the cellulose fiber obtained as above, which is a raw material for MFC, those in which at least a part of the fibrous shape is maintained even when dispersed in water are used. If those in which the fibrous shape is not maintained (i.e., those that dissolve in the dispersion medium) are used, microfibril cellulose cannot be obtained. By maintaining the fibrous form, a physically strong network is retained even in the soil, and different from the cellulose-based polymer in dissolved form, it is difficult to flow out of the system especially when moisture such as rain flows in. Particularly, having a fiber shape with a submicron size makes it excellent in workability, so that it can be uniformly sprayed and mixed into the soil, and the water retention capacity of the soil can be dramatically increased and an infiltration suppressing effect can be obtained. That at least a part of the fibrous shape is maintained when dispersed means that when the dispersion of cellulose fibers is observed with an electron microscope, fibrous substances can be observed. Also, cellulose fibers in which peaks of cellulose I-type crystals can be observed when measured by X-ray diffraction are preferred.

[0050] The crystallinity of cellulose in the cellulose fiber is preferably 50% or more, more preferably 60% or more, of crystalline form I. By adjusting the crystallinity within the above range, crystalline cellulose fibers that do not dissolve even after fibrillation of the fibers can be sufficiently obtained. The crystallinity of cellulose I in MFC is preferably 50% or more, more preferably 60% or more. The crystallinity of cellulose can be controlled by the crystallinity of the raw material cellulose and the degree of chemical modification. The method for measuring the crystallinity of cellulose fibers and MFC is as follows: Place the sample on a glass cell and measure it using an X-ray diffractometer (LabX XRD-6000, manufactured by Shimadzu Corporation). The crystallinity is calculated using the method of Segal et al. Using the diffraction intensity in the range of 2θ = 10° to 30° of the X-ray diffraction pattern as the baseline, it is calculated from the diffraction intensity of the 002 plane at 2θ = 22.6° and the diffraction intensity of the amorphous part at 2θ = 18.5° by the following formula.

[0051] Xc=(I002c-Ia) / I002c×100 Xc: Crystallinity of cellulose in crystalline form I (%) I002c: Diffraction intensity of the 002 plane at 2θ = 22.6° Ia: Diffraction intensity of the amorphous part at 2θ = 18.5°

[0052] (Fibrillation) The obtained cellulose fibers can be defibrated to obtain MFC. The apparatus used for defibration is not particularly limited, and examples include high-speed rotation type, colloid mill type, high-pressure type, roll mill type, ultrasonic type, cavitation jet apparatus, refining apparatus (refiner, for example, disk type, conical type, cylinder type refiner), high-speed defibrator, shear type stirrer, colloid mill, high-pressure injection disperser, beater, PFI mill, kneader, disperser, high-speed disintegrator (top finisher), high-pressure or ultra-high pressure homogenizer, cavitation jet apparatus, grinder (mortar type pulverizer), ball mill, vibration mill, bead mill, single-axis, two-axis or multi-axis kneader / extruder, homomixer under high-speed rotation, defibrator, friction grinder, high-shear defibrator, disperger, homogenizer (for example, microfluidizer), disintegrator (top finisher), homomicline mill, Henschel mixer, and other apparatuses. The number of passes (treatment times) in the defibrating apparatus may be once or two or more times, and two or more times are preferred.

[0053] (MFC) By defibrating the above-mentioned cellulose fibers, MFC can be obtained. In this specification, "MFC" (microfibrillated cellulose) refers to cellulose-derived fibers refined to the nanometer to submicron level, and may include nanofibers with a fiber width of about 2 to 100 nm and submicron-level cellulose-derived microfibers with a fiber width of more than 100 nm to about 20 μm. The average fiber diameter of MFC is preferably 100 nm or more and 20 μm or less, more preferably 200 nm or more and 20 μm or less, still more preferably 300 nm or more and 20 μm or less, and even more preferably 500 nm or more and 20 μm or less. The aspect ratio can be calculated by dividing the average fiber length by the average fiber diameter. The aspect ratio is preferably 10 or more, more preferably 30 or more. The upper limit of the aspect ratio is not limited, but is about 500 or less.

[0054] The measurement of the average fiber diameter and average fiber length was performed, for example, using a fractionator manufactured by Bühler AG on a sample obtained by diluting the MFC hydrogel to a solid content concentration of 0.25% by mass, and was determined as the length-weighted fiber width. The measurement was carried out twice, and the average values of the obtained fiber diameter and fiber length were adopted.

[0055] The added weight (solid) of the microfibrillated cellulose with respect to 100 parts by weight of the fertilizing liquid obtained by mixing the fertilizer and the microfibrillated cellulose is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, and even more preferably 0.1 to 0.5 parts by weight. By the added weight of the microfibrillated cellulose being within the above range, the water retention effect by the microfibrillated cellulose can be exhibited well.

[0056] The added weight (solid) of the microfibrillated cellulose with respect to 100 parts by weight of the soil can be used without particular limitation, but is preferably 0.01 to 5 parts by weight, more preferably 0.01 to 1 part by weight, and even more preferably 0.02 to 0.5 parts by weight. By the added weight of the microfibrillated cellulose being within the above range, the water retention effect by the microfibrillated cellulose can be exhibited well.

[0057] (Optional component) The soil conditioner may contain components other than the fertilizer and the microfibrillated cellulose (optional components) as necessary. Examples of the optional components include optional components (auxiliaries for preparations) such as excipients, colorants, preservatives, pH adjusters, stabilizers, disintegrants, carriers, binders, pH regulators, defoaming agents, nonionic surfactants, cationic surfactants, and amphoteric surfactants. The usage amount of the optional components is usually 0 to 30% by weight with respect to the microfibrillated cellulose or the composition.

[0058] (Dosage form · Manufacturing method) Examples of the dosage form of the soil conditioner include, but are not limited to, granular, pelletized, and liquid forms. Granular and pelletized forms can facilitate spreading. Also, the liquid form can ease mixing with functional components and stabilize the slurry after mixing. The soil conditioner may be formulated together with the functional components or separately. The manufacturing method of the soil conditioner can be appropriately selected according to the dosage form.

[0059] (Method of fertilizing soil) The method of fertilizing soil is not particularly limited. However, a mixture of fertilizer and MFC may be applied to the soil, or fertilizer may be applied to soil that has been previously well-mixed with MFC. At this time, the shape of MFC may be a state of being dispersed in water or a dry powder form.

[0060] In the present invention, carboxymethylated microfibrillated cellulose may be used in a dispersed state, or it may be dried (removing the dispersion medium), pulverized, and classified and then used as a powder.

[0061] When carboxymethylated microfibrillated cellulose used in the present invention is used as a powder, other components may be included if necessary. For example, when producing the powder, it is preferable to coexist a water-soluble polymer in the dispersion of carboxymethylated microfibrillated cellulose before drying, as the redispersibility is improved. The reason for the improved redispersibility by the water-soluble polymer is not clear, but it is presumed that the water-soluble polymer covers the portion with a low charge density on the surface of carboxymethylated microfibrillated cellulose and suppresses the formation of hydrogen bonds to prevent the aggregation of microfibrillated cellulose during drying.

[0062] (Water-soluble polymer) When using carboxymethylated microfibrillated cellulose as a powder, examples of water-soluble polymers that can coexist during powder production include, for example, cellulose derivatives (carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose), xanthan gum, xyloglucan, dextrin, dextran, carrageenan, locust bean gum, alginic acid, alginate, pullulan, starch, arrowroot starch, kudzu starch, modified starch (cationized starch, phosphorylated starch, phosphoric acid cross-linked starch, phosphoric acid monoesterified phosphoric acid cross-linked starch, hydroxypropyl starch, hydroxypropylated phosphoric acid cross-linked starch, acetylated adipic acid cross-linked starch, acetylated phosphoric acid cross-linked starch, acetylated oxidized starch, sodium octenyl succinate starch, acetic acid starch, oxidized starch), corn starch, gum arabic, locust bean gum, gellan gum, polydextrose, pectin, chitin, water-soluble chitin, chitosan, casein, albumin, soy protein hydrolyzate, peptone, polyvinyl alcohol, polyacrylamide, sodium polyacrylate, polyvinyl pyrrolidone, polyvinyl acetate, polyamino acid, polylactic acid, poly(lactic acid), polyglycerol, latex, rosin sizing agent, petroleum resin sizing agent, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide-polyamine resin, polyethyleneimine, polyamine, plant gum, polyethylene oxide, hydrophilic cross-linked polymer, polyacrylate, starch polyacrylate copolymer, tamarind gum, guar gum, and colloidal silica, as well as mixtures of one or more of these. Among these, cellulose derivatives are preferred from the viewpoint of affinity with carboxymethylated microfibrillated cellulose, and carboxymethyl cellulose and its salts are particularly preferred. Water-soluble polymers such as carboxymethyl cellulose and its salts are thought to enter between carboxymethylated microfibrillated cellulose particles and increase the distance between microfibrillated cellulose particles, thereby improving redispersibility.

[0063] When using carboxymethyl cellulose or its salt as the water-soluble polymer, it is preferable to use carboxymethyl cellulose having a degree of carboxymethyl group substitution of 0.55 to 1.6 per anhydroglucose unit, more preferably 0.55 to 1.1, and even more preferably 0.65 to 1.1. Also, those with longer molecules (higher viscosity) are preferable because they have a higher effect of widening the distance between microfibrillated celluloses. Further, the B-type viscosity at 25 °C and 60 rpm in a 1% by mass aqueous solution of carboxymethyl cellulose is preferably 3 mPa·s to 14,000 mPa·s, more preferably 7 mPa·s to 14,000 mPa·s, and even more preferably 1,000 mPa·s to 8,000 mPa·s. Here, the "carboxymethyl cellulose or its salt" as the water-soluble polymer is completely soluble in water, and thus is distinguished from the carboxymethylated microfibrillated cellulose whose fiber shape can be confirmed in water as described above.

[0064] The blending amount of the water-soluble polymer is preferably 5% by mass to 300% by mass, more preferably 20% by mass to 300% by mass, even more preferably 25% by mass to 200% by mass, and even more preferably 25% by mass to 60% by mass, based on 100% by mass in total of the carboxymethylated microfibrillated cellulose (absolute dry solid content) and the water-soluble polymer. When the water-soluble polymer is blended in an amount of 5% by mass or more, the effect of improving redispersibility can be obtained. On the other hand, when the blending amount of the water-soluble polymer exceeds 300% by mass, problems such as a decrease in viscosity characteristics such as thixotropy, which is a characteristic of carboxymethylated microfibrillated cellulose, and dispersion stability may occur. When the blending amount of the water-soluble polymer is 25% by mass or more, particularly excellent redispersibility can be obtained, which is preferable. Also, considering thixotropy, it is preferably 200% by mass or less, and particularly preferably 60% by mass or less.

[0065] (Drying) By drying a dispersion of carboxymethylated microfibrillated cellulose, or a dispersion of carboxymethylated microfibrillated cellulose mixed with a water-soluble polymer as appropriate (removing the dispersion medium), a dry solid containing carboxymethylated microfibrillated cellulose is obtained. At this time, it is preferable to adjust the pH of the dispersion to 9 to 11 and then dry it, because the redispersibility becomes even better.

[0066] As the drying method, known methods can be used and are not particularly limited. For example, spray drying, pressing, air drying, hot air drying, and vacuum drying can be mentioned. The drying device is not particularly limited, but continuous tunnel drying devices, band drying devices, vertical drying devices, vertical turbo drying devices, multi-stage disk drying devices, ventilation drying devices, rotary drying devices, pneumatic drying devices, spray dryer drying devices, spray drying devices, cylindrical drying devices, drum drying devices, belt drying devices, screw conveyor drying devices, rotary drying devices with heating tubes, vibrating conveyor drying devices, batch box-type drying devices, ventilation drying devices, vacuum box-type drying devices, and stirring drying devices, etc. can be used alone or in combination of two or more.

[0067] Among these, it is preferable from the viewpoint of energy efficiency to use a device that forms a thin film and dries, because thermal energy can be directly supplied to the object to be dried uniformly, and the drying process can be carried out more efficiently and in a short time. In addition, the device that forms a thin film and dries is also preferable in that the dried product can be recovered immediately by a simple means such as scraping the thin film. Furthermore, it has also been found that when drying is carried out after forming a thin film, the redispersibility is further improved. Examples of the device that forms a thin film and dries include drum drying devices and belt drying devices that form a thin film on a drum or a belt and dry it with a blade, a die, or the like. The film thickness of the thin film when forming and drying the thin film is preferably 50 μm to 1000 μm, and more preferably 100 μm to 300 μm. When it is 50 μm or more, scraping after drying is easy, and when it is 1000 μm or less, a further improvement effect on redispersibility can be observed.

[0068] The residual moisture content after drying is preferably 2% by mass to 15% by mass based on the entire dried product.

[0069] (Grinding) The grinding method is not particularly limited, and known methods can be used. Examples include a dry grinding method for processing in a powder state and a wet grinding method for processing in a state of being dispersed or dissolved in a liquid. When performing wet grinding, it may be carried out before the above drying.

[0070] Examples of the apparatus used in the dry grinding method include, but are not limited to, a cutting mill, an impact mill, a pneumatic mill, and a media mill. These can be used alone or in combination, and further, several-stage processing can be carried out with the same model. Among these, a pneumatic mill is preferred. Examples of the cutting mill include a mesh mill (manufactured by Horai Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuba Seisakusho Co., Ltd.), a knife mill (manufactured by Pallmann), a granulator (manufactured by Herbold), a rotary cutter mill (manufactured by Nara Kikai Seisakusho Co., Ltd.), etc. Examples of the impact mill include a pulpizer (manufactured by Hosokawa Micron Corporation), a fine impact mill (manufactured by Hosokawa Micron Corporation), a super micron mill (manufactured by Hosokawa Micron Corporation), a sample mill (manufactured by Seishin Co., Ltd.), a bantam mill (manufactured by Seishin Co., Ltd.), an atomizer (manufactured by Seishin Co., Ltd.), a tornado mill (manufactured by Nikkiso Co., Ltd.), a turbo mill (manufactured by Turbo Kogyo Co., Ltd.), a bevel impactor (manufactured by Aikawa Tekko Co., Ltd.), etc. Examples of the pneumatic mill include a CGS type jet mill (manufactured by Mitsui Mining Co., Ltd.), a jet mill (manufactured by Sanjo Industry Co., Ltd.), an Ebara jet micronizer (manufactured by Ebara Corporation), a Selene mill (manufactured by Masayuki Sangyo Co., Ltd.), a supersonic jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), etc. Examples of the media mill include a vibration ball mill, etc. Examples of the apparatus used in the wet grinding method include a mascoloider (manufactured by Masayuki Sangyo Co., Ltd.), a high-pressure homogenizer (manufactured by Sanmaru Kikai Kogyo Co., Ltd.), and a media mill. Examples of the media mill include a bead mill (manufactured by Aimax Co., Ltd.), etc.

[0071] (Classification) After the carboxymethylated microfibrillated cellulose is pulverized, classification is carried out and adjusted to a specific particle size. The method of classification is not particularly limited, and for example, it can be carried out by passing through a mesh (sieve) having a predetermined mesh opening. As the mesh, preferably 20 to 400 meshes, more preferably 40 to 300 meshes, and even more preferably 60 to 200 meshes can be used, and these may be used in a multi-stage manner. The median diameter of the finally obtained powder is 10.0 μm to 150.0 μm, preferably 30.0 μm to 130.0 μm, and even more preferably 50.0 μm to 120.0 μm.

Example

[0072] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In the following description, "parts" represents "parts by mass" unless otherwise specified.

[0073] (Production Example 1: Production of Oxidized MFC) 40 kg (dry weight) of bleached unbeaten kraft pulp derived from softwood (whiteness 85%: manufactured by Nippon Paper Industries Co., Ltd.) was added to 4000 L of an aqueous solution in which 312 g of TEMPO (manufactured by Sigma Aldrich) (0.05 mmol per 1 g of dry cellulose) and 4112 g of sodium bromide (1.0 mmol per 1 g of dry cellulose) were dissolved, and stirred until the pulp was uniformly dispersed. An aqueous sodium hypochlorite solution was added to the reaction system so that sodium hypochlorite became 5.5 mmol / 1 g of dry cellulose, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, but a 3M aqueous sodium hydroxide solution was sequentially added to adjust the pH to 10. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system no longer changed. After adding hydrochloric acid to the reaction mixture to adjust the pH to 2, dehydration and dilution with water were repeated to thoroughly wash the pulp, and finally dehydrated until the pulp solid content concentration reached 20% by weight to obtain a carboxy-modified pulp (oxidized pulp).

[0074] The obtained carboxy-modified pulp was dispersed in ion-exchanged water, and sodium hydroxide was added and stirred to obtain an aqueous dispersion of carboxy-modified pulp with a pH of 8.8 and a solid content concentration of 1% by weight. This aqueous dispersion of carboxy-modified pulp was treated 10 times with a cavitation jet device at 7 MPa to obtain an aqueous dispersion of oxidized MFC. The amount of carboxyl groups in the obtained oxidized CNF was 1.41 mmol / g, the average fiber diameter was 9.1 μm, and the average fiber length was 0.079 mm.

[0075] (Example 1) <Preparation of fertilizing solution> A liquid fertilizer (Hyponica, manufactured by Kyowa Co., Ltd.) was diluted using the aqueous dispersion of oxidized MFC (solid content concentration: 2% by weight) obtained in Production Example 1 and water to obtain 250 ml of a mixed solution in which the liquid fertilizer concentration was diluted 500-fold and the oxidized MFC solid content concentration was 0.05% by weight. The obtained mixed solution was stirred and mixed at 1000 rpm for 1 minute using a homodisper (trade name "High-speed Disperser Homodisper", manufactured by PRIMIX Corporation) to obtain a fertilizing solution.

[0076] <Fertilization on soil> 100 g of soil was placed in a 250-ml transparent container (Pack Clean), and leveled so that the soil surface was horizontal. Then, 50 ml of the fertilizing solution obtained above was uniformly sprayed on the soil surface using a sprayer.

[0077] (Example 2) A fertilizing solution was prepared and soil spraying was carried out in the same manner as in Example 1, except that a mixed solution with an oxidized MFC solid content concentration adjusted to 0.1% by weight was prepared.

[0078] (Example 3) A fertilizing solution was prepared and soil spraying was carried out in the same manner as in Example 1, except that a mixed solution with an oxidized MFC solid content concentration adjusted to 0.2% by weight was prepared.

[0079] (Comparative Example 1) A fertilizing solution was prepared and soil spraying was carried out in the same manner as in Example 1, except that the liquid fertilizer was diluted 500-fold with only water without using oxidized MFC.

[0080] <Evaluation method> (Initial permeability evaluation) Regarding the permeability of the fertilizing solution immediately after soil spraying, visual observation was carried out from the side of the transparent container, and the permeability of the fertilizing solution on the soil surface layer (about 2 cm from the soil surface) was evaluated according to the following criteria. ◎: There is a liquid pool on the soil surface layer, and the fertilizing solution stays on the soil surface layer and hardly penetrates. 〇: Slight penetration can be seen inside the soil, but most of the fertilizing solution stays on the soil surface layer. ×: It has penetrated to the inside of the soil.

[0081] (Permeability evaluation over time) Regarding the permeability of the fertilizing solution 4 hours after soil spraying, the evaluation was carried out in the same manner as described above.

[0082]

Table 1

[0083] (Example 4) (Growth test of cherry tomatoes) 200 g of potting soil (a mixed soil of peat moss, coco peat, and vermiculite) was put into a pot with a diameter of 11.3 cm and a height of 9 cm. After planting cherry tomato seedlings, 50 ml of the fertilizing solution obtained in Example 3 was uniformly sprayed on the soil surface. Using an LED light (manufactured by Youying Co., Ltd., model number UH-CB01), irradiation was carried out for 16 hours per day, and growth continued for one week.

[0084] (Comparative Example 2) A growth test of cherry tomatoes was carried out in the same manner as in Example 4, except that the fertilizing solution of Comparative Example 1 was used.

[0085] <Evaluation method> (Observation of cherry tomato growth) Regarding the growth status of cherry tomatoes after one week of growth, visual observation was carried out and evaluated according to the following criteria. 〇: Compared with the cherry tomatoes in Comparative Example 2, it is excellent in the elongation of stems and leaves and has good growth. ×: Equivalent to the cherry tomatoes of Comparative Example 2.

[0086]

Table 2

[0087] As shown in Examples 1 to 3, with the soil preparation agent and soil adjustment method for plant cultivation of the present invention, since the fertilizer solution does not stay on the soil surface, an improvement in the fertilizer efficiency used for plant growth is expected. Furthermore, it can be seen that when the solid content concentration of microfibrillated cellulose increases, the osmosis suppression effect over time also improves. Also, according to Example 4, a clear growth promotion was confirmed in the growth of cherry tomatoes.

Claims

1. A method for preparing a soil for plant cultivation, characterized by adding a fertilizer and microfibrillated cellulose to the soil.

2. The method for preparing a soil for plant cultivation according to Claim 1, wherein the added weight of the microfibrillated cellulose is 0.01 to 5 parts by weight with respect to 100 parts by weight (dry weight) of the soil.

3. The method for preparing a soil for plant cultivation according to Claim 1 or 2, characterized in that the microfibrillated cellulose contains a carboxymethyl group.

4. The method for preparing a soil for plant cultivation according to Claim 3, characterized in that the degree of substitution of the carboxymethyl group in the microfibrillated cellulose is 0.01 to 0.

50.

5. The method for preparing a soil for plant cultivation according to Claim 1 or 2, characterized in that the microfibrillated cellulose contains a carboxyl group.

6. The method for preparing a soil for plant cultivation according to Claim 5, characterized in that the amount of carboxyl groups in the microfibrillated cellulose is 1.0 to 2.0 mol / g.

7. A soil preparation agent for plant cultivation, characterized by containing a fertilizer and microfibrillated cellulose.

8. A method for producing a plant, characterized by using a soil preparation agent for plant cultivation, which contains a fertilizer and microfibrillated cellulose.

9. A plant growth promoter, characterized by containing a fertilizer and microfibrillated cellulose.

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