JPH0123439B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention absorbs or adsorbs fertilizer components into a highly water-absorbent gel made of a homopolymer of acrylamide or a copolymer of acrylamide and acrylic acid (however, part or all of the acrylic acid may be an alkali metal salt). The present invention relates to a new type of fertilizer characterized by the following characteristics: Plant growth requires nitrogen, phosphorus, potassium, manganese, zinc, iron, copper, molybdenum, boron,
Trace elements such as magnesium are also known to be necessary. In order to effectively and appropriately supply these fertilizer components to plants, fertilizers include solid fertilizers in the form of granules, powder, pellets, etc., and liquid fertilizers in the form of an aqueous solution. In addition, various efforts have been made to make the fertilizer fast-acting or slow-acting. Rapid-release fertilizers are fertilizers that are either liquid or highly soluble in water, and are designed so that the fertilizer components are quickly dissolved in the soil moisture and the fertilizer effect appears quickly. On the other hand, slow-release fertilizers are made into granules so that the fertilizer components gradually dissolve in the soil moisture, reducing the area of contact with the soil moisture, or by using salts that are sparingly soluble in water. There is. Furthermore, we have developed methods such as reacting formaldehyde with urea to make it more slow-release than urea alone, coating the surface of water-soluble fertilizers so that they gradually elute, and adding various metal ions, which are fertilizer components, to ion-exchange resins. Adsorbed fertilizers are known. However, although fast-release fertilizers can be applied according to the growth stage of the plant and can quickly produce fertilizer effects, they are difficult to diffuse into the soil, have a short effective period, and most of the fertilizer is washed away by rainwater. There are disadvantages such as a lot of waste. In addition, although the effective period of various currently known slow-release fertilizers is long, the solubility in water is too low due to chemical reactions and variations in the degree of coating, resulting in insufficient supply of fertilizer components. It has not taken shape. Fertilizers in which metal ions are adsorbed on ion exchange resins also have a drawback in that the amount of fertilizer components eluted is low. The present inventors have developed a superabsorbent gel consisting of a homopolymer of acrylamide or a copolymer of acrylamide and acrylic acid (part or all of which may be an alkali metal salt or an alkaline earth metal salt). We discovered that when fertilizer components are absorbed or adsorbed, they elute again depending on their composition, quickly elute as water-soluble components, and do not easily flow out even in the presence of a large amount of water. The present invention has now been completed. In other words, the fertilizer of the present invention has the advantages of a fast-acting fertilizer in that it supplies the fertilizer components required by plants in a well-balanced manner and exhibits fertilizer effects quickly, and at the same time uses a highly absorbent gel as a fertilizer carrier. Therefore, it is possible to prevent fertilizer components from being washed away into the soil by rainwater, thereby extending the period of fertilizer effectiveness. The superabsorbent gel used in the present invention includes an acrylamide homopolymer, a copolymer of acrylamide and acrylic acid, and a gel in which part or all of acrylic acid is replaced with an alkali metal salt or an alkaline earth metal salt of acrylic acid. Copolymers are used.
Gel made of acrylamide homopolymer has excellent water absorption, but by copolymerizing acrylic acid, the water absorption rate becomes even higher, it becomes able to adsorb metal ions, and it also absorbs fertilizer components well. Gels copolymerized with acrylates such as sodium acrylate and potassium acrylate have high water absorption rates and water absorption rates. However, gels made of homopolymers of acrylic acid or acrylic acid salts, or gels made of copolymers of both have low absorption of aqueous solutions of fertilizer components and are difficult to elute, resulting in failure to elute well-balanced fertilizer components. Therefore, the superabsorbent gel used in the present invention preferably has a copolymerization ratio of acrylamide and acrylic acid in a monomer molar ratio of 100:0 to 50:50, preferably 95:5 to 70: Copolymers in the range of 30 are more suitable. Further, by using N,N'-methylenebisacrylamide or ethylene dimethacrylate as a crosslinking agent, water absorption rate, water absorption rate, hardness upon water absorption, etc. can be adjusted. The polymerization reaction for obtaining a superabsorbent gel can be carried out by aqueous solution polymerization or suspension polymerization in an organic solvent. As the initiator, an initiator such as peroxonisulfate which is normally used for radical polymerization of vinyl compounds can be used, and polymerization can also be carried out at low temperature by using a combination of redox-based initiators. For example, in aqueous solution polymerization, the monomer concentration is 10-40%.
Polymerization is carried out at room temperature using a redox-based initiator to reduce the initiator concentration, and N,N'-bismethylene acrylamide is used as a crosslinking agent. The obtained gel is dried and pulverized into an appropriate size, such as powder or granules, depending on the purpose of use, to obtain a dry gel of any particle size. Drying is generally carried out by hot air drying at a temperature of 70°C or lower, preferably 50 to 60°C. The dry gel used in the present invention has the ability to absorb 20 to 500 times its weight of ion-exchanged water, and it is suitable that it has an absorption and adsorption capacity of 5 to 50 times the weight of a 40% fertilizer component aqueous solution. The novel fertilizer of the present invention is made by absorbing or adsorbing fertilizer components into such a gel, and an aqueous solution of the fertilizer components is used to absorb or adsorb the fertilizer components into the gel. As such an aqueous solution, aqueous solutions of inorganic and organic compounds commonly used as fertilizer components can be used. Inorganic compounds include various nitrates, sulfates, phosphates, and carbonates of fertilizer components, and organic compounds include urea, amino acid byproducts, and sugars. Further, solubility promoters, suspending agents, surfactants, chelating agents such as EDTA, etc. which are commonly used for preparing these aqueous solutions may be added as appropriate. This aqueous solution is brought into contact with the dry gel and left until desired absorption and adsorption occur. Generally 24
~48 hours is sufficient. The concentration of this aqueous solution and the quantitative relationship between the aqueous solution and the gel vary greatly depending on the types and proportions of fertilizer components, the water absorption capacity of the gel, etc., so these cannot be uniformly specified, but from an economical point of view Considering this, it is preferable to use an aqueous solution with a high concentration of fertilizer components and to absorb and adsorb this into a gel with a high water absorption capacity. Therefore, the amount of fertilizer components absorbed into the dry gel varies depending on the concentration of each component in the aqueous fertilizer solution used, the amount of liquid, and the water absorption capacity of the gel, and by adjusting these appropriately, it is possible to create a fertilizer with desired characteristics. can be manufactured. In other words, it is possible to supply a unique fertilizer that can be applied depending on the type of plant, season, type of soil in the area, etc. For example, vegetables absorb nitrogen, phosphorus, potassium, calcium, and magnesium well, so they can be blended with large amounts of these ingredients, and fruits can be blended with large amounts of potassium and magnesium, as well as boron, manganese, and zinc. ,
Fertilizers of the present invention suitable for each plant can be made. The gel that has absorbed and adsorbed fertilizer components can be applied to soil as is, or it can be applied in the form of granular fertilizer in which only the water is evaporated and dried while the fertilizer components are retained in the gel. In this case, drying is preferably carried out by hot air drying at a temperature of 70°C or lower, preferably 50 to 60°C. It is also possible to fertilize with a mixture of sand, silica gel, perlite, super absorbent resin, etc. in any proportion. The new fertilizer according to the present invention has a well-balanced elution of the components absorbed by the water in the soil into an aqueous solution by diffusion, so that the fertilizer effect appears quickly. Furthermore, when the moisture in the soil increases rapidly due to rainwater or irrigation, the superabsorbent gel reabsorbs the aqueous solution of fertilizer components to its maximum capacity, thereby preventing the fertilizer components from being washed away. Therefore, the fertilization period can be prolonged, and plant growth can be significantly promoted by improving the water retention and air permeability of the soil. The present invention will be explained below with reference to Examples. Example 1 120g of acrylamide and 122g of acrylic acid were mixed with water.
Dissolve in 360 ml and add 0.2 g of N,N'-methylenebisacrylamide. While stirring and blowing nitrogen gas, 0.12 g of ammonium peroxodisulfate and 0.07 g of sodium bisulfite are added, and the mixture is allowed to react at room temperature for 5 hours. The resulting gel is dried and ground. 1200g of water, 255g of phosphoric acid, 255g of potassium hydroxide
Dissolve 75g of potassium chloride, 570g of amino acid solution and 480g of urea and add water to make a total of 3Kg.
Add the pulverized dry gel to the fertilizer component solution.
100g was soaked and left for 48 hours. The gel that had absorbed the fertilizer components was dried at 50 to 60°C to obtain 840 g of the fertilizer of the present invention. The ingredient content of this fertilizer is nitrogen 20
%, phosphoric acid 13.3%, and potassium 14.1%. When 1 g of this fertilizer was immersed in 100 ml of water for 48 hours, the elution rate of each component into the water, including nitrogen, phosphoric acid, and potassium, was 98%. Example 2 Potassium peroxodisulfate 15 was added to 300 g of a 10% acrylamide aqueous solution while stirring and blowing nitrogen gas.
mg and 8 mg of sodium bisulfite are added and polymerized at room temperature. It thickens and becomes a gel in about 1 hour. The resulting gel was dried and ground to a particle size of 10 meshes. Dissolve 8.4 g of ammonium molybdate in 1000 g of water, add hydrochloric acid to make it weakly acidic, add 64 g of manganese chloride, 38 g of boric acid, 114 g of ferrous sulfate, and copper sulfate.
100 g of the pulverized dry gel was immersed in a fertilizer component solution in which 66.6 g and 74.8 g of zinc sulfate were sequentially dissolved and water was added to make a total amount of 2.0 kg, and left for 48 hours. The gel that has absorbed the fertilizer components is dried at 50 to 60℃.
g of the fertilizer of the present invention was obtained. The component content of this fertilizer was 4.7% manganese, 2.8% boron, 2.8% iron, 2.9% copper, 2.5% zinc, and 0.66% molybdenum. When 1 g of this fertilizer was soaked in 100 ml of water for 48 hours, the elution rate of each component into the water was 98.2 manganese.
%, boron 100%, iron 68.0%, copper 96.1%, zinc 97.3
%, molybdenum 97.0%. Example 3 284g of acrylamide and sodium acrylate
Dissolve 94 g in 570 ml of water and add 0.5 g of N,N'-methylenebisacrylamide. Ammonium peroxodisulfate 0.2g and sodium bisulfite
Add 0.1g and heat at room temperature for 5 minutes while blowing nitrogen gas.
Allow time to polymerize. The resulting gel is dried and ground. 1.89 g of ammonium molybdate in 450 g of water,
Boric acid 0.9g, potassium hydroxide 59.4g, phosphoric acid 77.4g
g, citric acid 27g, magnesium sulfate 61.2g, manganese chloride 3.24g, EDTA-iron 8.1g, EDTA-
0.72 g of copper, 0.72 g of EDTA-zinc, and 138.6 g of ammonium nitrate were sequentially added and dissolved, and 100 g of the pulverized dry gel was immersed in the fertilizer component solution to make a total amount of 900 g by adding water and left for 48 hours. Dry the gel that has absorbed fertilizer components at 50 to 60℃.
430 g of the fertilizer of the invention was obtained. The ingredient content of this fertilizer is 10.5% nitrogen and phosphorus.
9.5%, potassium 10.5%, magnesium 1.9%, manganese 0.22%, boron 0.13%, iron 0.19%, copper 0.02
%, zinc 0.02%, and molybdenum 0.19%. When 1 g of this fertilizer was soaked in 100 ml of water for 48 hours, the elution rate of each component into the water was 88.7% nitrogen, 90.8% phosphoric acid, 87.8% potassium, 93.6% magnesium,
Manganese 81.4%, Boron 80.5%, Iron 98.9%, Copper
72.5%, zinc 86.3%, and molybdenum 98.7%. Example 4 An aqueous sodium hydroxide solution required to neutralize 50% of acrylic acid was gradually added to 135 g of acrylic acid while cooling, and a portion of the acrylic acid was converted into sodium acrylate. Add this solution and 765g of acrylamide to 2
of water, and 2 g of N,N'-methylenebisacrylamide was added. While blowing nitrogen gas, 0.5 g of potassium peroxonisulfate and 0.3 g of sodium bisulfite were added, and polymerization was carried out at room temperature for 3 hours. The resulting gel was dried and ground. On the other hand, 1.5 kg of water contains 34.4 g of potassium nitrate, 26.0 g of ammonium phosphate, 17.0 g of calcium nitrate, 23.0 g of ammonium nitrate, and 27.0 g of magnesium sulfate.
g, manganese sulfate 2.0g, boric acid 0.4g, zinc sulfate
1.76 g and 1.58 g of copper sulfate were sequentially added and dissolved, and water was added to prepare a total of 2 kg, an aqueous solution of fertilizer components. Add 100g of the above dry gel to this aqueous solution and soak for 48 hours, then dry at 50-60℃.
200g of the fertilizer of the invention was obtained. The content of each component in the fertilizer thus obtained was 7.9% nitrogen, 6.8% phosphoric acid (P ₂ O ₅ ), 7.3% potassium (K ₂ O), 1.9% calcium (CaO), and 2.2% magnesium. , manganese (MnO) 0.26%, boron (B ₂ O ₃ ) 0.09%, copper 0.18%, and zinc 0.16%. When 1 g of this fertilizer is soaked in 100 ml of water for 48 hours, the elution rate of each component into water is 87.0% nitrogen, 95.3% phosphoric acid, 95.7% potassium, 92.2% calcium,
Magnesium 88.6%, Manganese 100%, Boron
79.3%, copper 91.6%, and zinc 100%. Example 5 In 2.5 kg of water, 103.2 g of potassium nitrate, 78 g of ammonium phosphate, 87 g of ammonium nitrate, 81 g of magnesium sulfate, 6 g of manganese sulfate, 1.2 g of boric acid,
Zinc sulfate 5.4g, copper sulfate 4.8g, EDTA-iron 15g,
12 g of EDTA was sequentially added, stirred and dissolved, and water was added to make a total amount of 3.0 kg to prepare a fertilizer component solution. 100 g of the dry gel obtained in the polymerization reaction of Example 4 was added to this solution and left to stand for 48 hours, and the gel that had absorbed the fertilizer components was dried at 50 to 60°C to obtain 300 g of the fertilizer of the present invention. The content of each component of this fertilizer is 10.0% nitrogen, 8.8% phosphoric acid (P ₂ O ₅ ), 9.0% potassium (K ₂ O), 2.6% magnesium (MgO), and manganese (MnO).
0.34%, boron (B ₂ O ₃ ) 0.12%, iron 0.34%, copper
0.23% and zinc 0.21%. A mixture of 5 g of this fertilizer and 95 g of silica gel was placed on a 17G-1 glass filter, and the mixture was soaked with sufficient water and left overnight. After that, 1
The entire mixture was dampened once a day with about 35 g of water, the runoff water was collected, and each fertilizer component eluted into the water was analyzed, and the results shown in Table 1 were obtained.

[Table] As is clear from this table, each component is eluted in a well-balanced manner, and approximately 50% or more of the fertilizer components are still retained. Comparative Example 1 In this comparative example, nitrogen 13.0%, phosphoric acid (P ₂ O ₅ ) 12.0%, potassium (K ₂ O) 12.0%, manufactured by Asahi Chemical Industries, Ltd.
Magnesium (MgO) 3.0%, Manganese (MnO)
0.6%, boron (B ₂ O ₃ ) 0.15%, iron (Fe) 0.45%,
Using a water-soluble fast-acting powder fertilizer containing 0.3% copper (Cu) and 0.3% zinc (Zn), a test was conducted in the same manner as in Example 5, and each fertilizer component eluted into the runoff water was analyzed. Ivy. The results are shown in Table 2.

[Table] As is clear from the data in Table 2, in the case of fast-acting powdered fertilizer, more than half of the fertilizer components are eluted in the first application, and from the second application onwards, the eluted components are extremely It can be seen that the elution balance decreases and the elution balance is poor. It can also be seen that most of the components flow out within a short period of time. Comparative Example 2 In this comparative example, a commercially available product manufactured by Takeda Horticultural Materials Co., Ltd. under the trade name Ede Ball was used. This fertilizer has nitrogen 12.0
%, phosphoric acid (P ₂ O ₅ ) 12.0%, potassium (K ₂ O)
12.0%, magnesium (MgO) 1.0%, manganese (MnO) 0.1%, and boron (B ₂ O ₃ ) 0.05%. Using the above fertilizer, a test was conducted in the same manner as in Example 5, and each fertilizer component eluted into the runoff water was analyzed. The results are shown in Table 3.

[Table] As is clear from the data in Table 3, with conventional slow-release fertilizers, overall dissolution is extremely slow. Comparative Example 3 In this comparative example, commercially available CDU Rinkaan S862 manufactured by Chitsuso Co., Ltd. was used. This fertilizer is a granular slow-release fertilizer containing 16.0% nitrogen, 8.0% phosphoric acid (P ₂ O ₅ ), and 12.0% potassium (K ₂ O), and is specifically a fertilizer in which urea is condensed with acetaldehyde. Using the above fertilizer, a test was conducted in the same manner as in Example 5, and each fertilizer component eluted into the runoff water was analyzed. The results are shown in Table 4.

[Table] As is clear from the data in Table 4, this slow-release fertilizer is relatively slow-release only for nitrogen, but phosphorus and potassium show the same elution rate as fast-release fertilizers. After that, the elution amount decreases rapidly and the elution balance is poor. In addition, the amount of nitrogen itself elutes is large in the first time, and decreases after the second time.
It can be seen that the elution balance is poor. On the other hand, as is clear from the data in Table 1 of Example 5, the fertilizer of the present invention maintains an appropriate dissolution rate of each fertilizer component, and moreover, all fertilizer components are eluted almost equally and in a well-balanced manner.

Claims (1)

[Scope of Claims] 1. A fertilizer characterized in that fertilizer components are absorbed or adsorbed in a highly water-absorbent gel made of an acrylamide homopolymer or a copolymer of acrylamide and acrylic acid. 2. The fertilizer according to claim 1, wherein part or all of the acrylic acid is an alkali metal salt or an alkaline earth metal salt of acrylic acid.