JP2019122269A - Method for manufacturing coated plant seed and coated plant seed - Google Patents

Abstract

To provide a method for manufacturing coated plant seeds and the coated plant seeds.SOLUTION: According to the present invention, a method for manufacturing coated plant seeds is provided that comprises: a step of manufacturing a mixture comprising a bonding aid selected from a constitution material, a bonding agent and PVA; a step of putting plant seeds in the mixture and mixing them, and thereby manufacturing a second mixture; and a step of forming the coating of the second mixture on the surfaces of the plant seeds while adding and mixing water to the second mixture. Also, according to the present invention, the plant seeds are provided that has the coating comprising a compound selected from the group comprising an iron oxide, an alkaline-earth metal oxide, a hydroxide, a carbonic acid salt or the mixture of one kind, two kinds and three kinds of those, and iron oxide powder selected from the group comprising FeO, FeO,FeO.HO, or the mixture of one kind, two kinds and three kinds of those.SELECTED DRAWING: None

Description

  The present invention relates to a method of producing coated plant seeds and to coated plant seeds.

  To attach or fix various extenders and binders on the surface of plant seeds singly or simultaneously, and for the purpose of ease of work at the time of sowing, positional stability after sowing, improvement of germination rate and growth promotion etc. Various methods have been proposed and implemented.

  For example, a method is known in which water and a water-soluble type pesticide (such as a bactericidal agent) are mixed, and the mixture is impregnated with the seed, taken out after a suitable time, dried and used. In addition, there is also known a method of taking out seeds sown in water, taking it out when it is in a state where sufficient moisture exists on the surface, mixing it with pesticide (such as bactericidal) powder and adhering it to the surface of seeds.

  Furthermore, a method of using iron oxide powder (baked powder of cast iron swarf) and 3% of CMC (sodium carboxymethylcellulose) as a binder, adding and mixing, adhering and drying on the surface of rice seed meal, calcium peroxide and calcined gypsum There is also known a method (carper coating) in which a rice seed meal is mixed with the rice seed meal and the like and the surface of the rice seed meal is coated while spraying water.

  In addition to these, a method of mixing reduced iron powder and calcined gypsum with rice seed meal and adding it to water to convert calcined gypsum (hemihydrate gypsum) to gypsum dihydrate (hydration reaction) and using it as a covering material, molybdenum trioxide and Water-resistant PVA (polyvinyl alcohol) is mixed with iron oxide powder (bengala) and water is added to make a film, mixed with slaked lime and iron oxide powder with rice seed and water is added to form a film and fixed How to do so is also proposed.

Patent document 1: JP-A-2005-192458 Patent 6,024,972 JP, 2016-189735, A

http: // www. pref. mie. lg. jp / common / content / 000167770. pdf (2001 Mie Science and Technology Research Institute Iga Agricultural Laboratory: Download dated December 27, 2017) http: // www. hodogaya-upl. com / products / pdf / apply / calper16. pdf (Kalper coating Hodogaya UPL Ltd .: Download dated December 27, 2017)

  In addition to the above reports, for example, starch paste, funori obtained from seaweed, acrylic ester emulsion obtained by emulsifying synthetic resin, etc. are considered as an adhesive to the surface of the seed, but all are water-soluble types and water content It takes a considerable amount of time for the water to evaporate and to dryness after being mixed with a large amount of iron, iron oxide, calcined gypsum, slaked lime, calcium carbonate, etc. When the amount of addition of the material is large, it precipitates on the surface of the film, and the film particles of the seeds adhere to each other to form a dumpling, which makes it difficult to separate them into independent individual particles. It is therefore necessary to find an anchoring method or anchoring material in which the coated seeds become as independent as possible.

  However, in the conventional method, water is evaporated on the surface of the seed and then dried and attached, and if mechanical strength, pressure, vibration or the like is applied, the seed surface may be easily peeled off. In addition, in the method of adding CMC to iron oxide powder, adding water and mixing treatment, drying takes time because of the hygroscopicity of CMC, and there is a problem in economy.

  The method of coating a seed meal with iron powder is one of the methods which has been put into practical use, but in this method, the heat is generated in the process of giving moisture at the time of film production to oxidize the iron powder. It has a serious effect of impairing the ability to germinate. Furthermore, iron expands as it becomes iron oxide, but it takes time and labor during manufacturing to form a film on the surface again with calcined gypsum to prevent cracking upon expansion. In addition to this, there is a problem that a long curing time is required to reduce and advance the oxidation, and it takes time and effort at the germination stage.

  In addition, the method of using molybdenum trioxide is intended to suppress the formation of sulfide in the paddy field and to reduce the decrease in seedling establishment. However, when molybdenum trioxide, iron oxide powder, PVA (polyvinyl alcohol) are mixed and water is added while forming film seeds, if a large amount of water is added, the seeds adhere to each other because of the adhesive action of PVA. There is a problem that it is in the form of dumplings and the workability is significantly deteriorated.

  Since the method using iron oxide powder uses iron oxide powder instead of reduced iron powder of the material, various obstacles due to heat generation of iron powder can be eliminated. However, slaked lime used as a binder requires the presence of water and carbon dioxide gas to solidify, and it takes a considerable time to develop a predetermined strength. In addition, if the calcium carbonate crystals produced by carbonation of slaked lime are small, the strength of the coating film as a whole will be weak, and it can be sprayed on the paddy field surface by manual operation, power sprayer, airborne sprayer etc. It was unsuitable for a large direct seeding machine.

  The present invention has been made in view of the above-mentioned conventional problems, and when forming a film using a reinforcing material and a binder on the surface of a plant seed, it is generated from the weak strength of the film formed during storage and use. The purpose is to provide a method for producing a coated plant seed which is suitable for direct seeding with a high specific gravity, which prevents deterioration of the quality of the seeds and workability significantly due to cracking and cracking, and to provide a coated plant seed. Do.

  In order to solve the above-mentioned problems of the prior art, the inventor of the present invention has long-term storage stability of the coated seed, absorbs water in the soil after sowing, and reaches the seed coating membrane, the binder in the coating membrane is A material that partially dissolves in water, makes a hole in the coating film and moisture is in direct contact with the seeds to promote sprouting, and the entire coating layer absorbs water to soften and make it easy for sprouts to come out of the coating layer and The search method and research were conducted.

  As a result, iron oxide powder or calcium carbonate powder may be used singly or in combination with both materials in an appropriate ratio, and as a binder, slaked lime as a main component and a hydrophilic partially saponified PVA fine powder as a bond strengthening agent. By treating a plant seed by adding and mixing it to a binder, it discovers that the said problem in a prior art is solvable, It came to this invention.

That is, according to the present invention,
Producing a mixture comprising a binding agent selected from an extender, a binder and PVA;
Adding plant seeds to the mixture and mixing to produce a second mixture;
Providing a film of the second mixture on the surface of the plant seed while mixing with the second mixture while adding water to provide a manufacturing method.

  The PVA can have a degree of saponification of 80 mol% to 90 mol%, a degree of polymerization of 500 to 2,500, and a particle size of 250 μm or less.

  The PVA can form a coating present at 2% by mass to 10% by mass with respect to the binder.

  The binder can be selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates or mixtures of one, two or three thereof.

The reinforcing material may be iron oxide powder selected from the group consisting of Fe ₂ O ₃ , Fe ₃ O ₄ , Fe ₂ O ₃ · H ₂ O, or a mixture of one, two or three thereof. Can.

Furthermore, according to a second aspect of the present invention, there is provided a compound selected from the group consisting of iron oxide, alkaline earth metal oxides, hydroxides, carbonates or mixtures of one, two or three thereof, And plant seeds having a coating comprising an iron oxide powder selected from the group consisting of Fe ₂ O ₃ , Fe ₃ O ₄ , Fe ₂ O ₃ .H ₂ O, or a mixture of one, two or three thereof Is provided.

  There are two major types of direct sowing methods for rice. One is direct soda seeding, and the other is direct sowing seed water. Although the present invention is applicable to any of them, an exemplary embodiment in which the present invention is applied to direct seeding of flooded water will be described below as an exemplary embodiment. Sprinkling direct seeding is a method for raising seedlings by sowing seed seeds on the water surface, settling them below the water surface, and causing them to germinate and survive. Since the drying kiln contains air and has a low apparent specific gravity, it floats on the water surface or floats in the water if the water is not well wetted. For this reason, the desiccant does not land on a predetermined position, but moves by the flow of a wind, a flow of water, or the like. To solve this problem, you should make the seed as heavy as possible.

Materials put into practical use as a covering material having a large unit mass on the surface of a seed meal are as follows.
(1) Calcium peroxide-gypsum system (2) Reduced iron powder-gypsum system (3) Molybdenum trioxide-iron oxide powder-PVA system (4) Iron oxide powder-slaked lime system

  The treatment method using calcium peroxide and calcined gypsum, and the method using molybdenum trioxide and iron oxide powder, PVA, have few elements that are deeply related to seed coating operation and direct sowing for direct seeding of flooded water, but rather sowing It is closely related to the growth promotion and sulfide removal etc. in connection with the later seed rice.

  The increase in apparent specific gravity is imparted by the bulk material, and iron, copper, nickel, lead, manganese, chromium, barium, molybdenum, hydroxides of zirconium, salts and the like can also be used with a relatively large specific gravity. Among them, in the present embodiment, an iron compound is used as the core material. The reason for this is that it is advantageous in terms of physical properties and cost as compared to other materials, and depending on the type of element, oxides and the like may also be harmful. More specifically, iron oxide is used as a reinforcing material because it is very stable chemically, has no action on plants, exists in a large amount, and is inexpensive unlike reduced iron. Is preferred. The composition of iron oxide is not limited as long as it is an oxide comprising iron and oxygen, such as ferrite, magnetite, hematite and goethite.

  The particle size used in the present invention is not the primary particle size, but primary particles aggregate to form secondary particles, and secondary particles further aggregate to form flocculate particle groups. Say the particle size. The aggregates are forced to break, disperse and have the desired average particle size. In general, the particle size refers to a particle size of, for example, 325 mesh or less (45 μm pass) in the case of a coating material, depending on the use, using a sieve according to the JIS standard. The primary particles of iron oxide are between about 0.1 and 1 μm, and black iron oxide is also present between about the same. These particles are not independent but are aggregated by hydrogen bonding due to mutual intermolecular force or the presence of water, and a dispersant or the like is required to obtain an average particle diameter of 10 μm or less. In addition, the color tone of the primary particles changes with the size of the particle size. Although it is an important factor in the paint industry, average particle size and density are important in this technical field.

The specific gravity of iron oxide is red iron oxide (hematite) Fe ₂ O ₃ and specific gravity is 4.9-5.1, black iron oxide (magnetite) Fe ₃ O ₄ is 4.2-5.2, yellow iron oxide in _{(goethite) Fe 2 O 3 · H 2} O, is 3.4-4.3. In the present embodiment, since the specific gravity of the coated seed can be efficiently increased as the density of the core material used is larger, magnetite having the largest specific gravity can be used as a preferable iron oxide compound.

  The particle size of iron oxide to be used is preferably about 45 μm, and the number average particle size can be in the range of 20 μm to 40 μm, but is not limited to this range.

  Covered seeds have been used in paddy fields relatively recently, so the development of seeders compatible with coated seeds is also new. There are various types and types of conventional sowing machines, but there are currently no sowing machines that can be adapted to film seeds. If you spread the seeds over a wide area, there are power sprayers, helicopters, aircrafts, etc., but it is difficult to cope with row seeding and point seeding freely. This may be one of the reasons why the direct seeding system does not grow. Coated seeds having a strength that can withstand the mechanical strength of a sowing machine that is widely used at present are Kubota's reduced iron powder-gypsum gypsum system system. The strength can be determined on the basis of the strength of this system.

The binder used in this embodiment may be any known binder such as calcined gypsum, slaked lime, magnesium oxide, strontium oxide, barium oxide, PVA, a water-soluble polymer such as PVA, carboxymethylcellulose, or a mixture of these. It can be used. Among these, in the present embodiment, it is preferable to use calcium hydroxide, which is a hydroxide of an alkaline earth metal, as calcium hydroxide (OH) ₂ . Furthermore, slaked lime is already widely used as a neutralizing agent in the agricultural field, and it can be used as a binder and is inexpensive if it takes advantage of the property of strong alkali, and it does not contain a sulfate group like gypsum, Both substances are advantageous in terms of handling such as easy handling in powder.

  Furthermore, in the present embodiment, a binding aid can be used. The bonding aid can be selected from polymeric materials. As the bonding aid that can be used, PVA, polyacrylic acid ester, styrene acrylic acid copolymer, styrene acrylic acid ester copolymer and the like can be mentioned. For example, as a polymer as a binding aid, PVA can be mentioned. PVA having a degree of saponification of 80 to 90%, a degree of polymerization of 500 to 2,500, and a particle size of 0.4 mm or less can be used as PVA which can be used in the present embodiment, and the addition amount In terms of stability against the above, particles having a particle size of 250 μm or less can be used.

  The iron oxide used in this embodiment can be 50 parts to 20 parts by weight of the plant seed. The binder may also be from 1 part to 5 parts by weight of the plant seed. In addition, the ratio of the binder to the binding aid can be 10% or less of the binding agent, more preferably 1% to 10%, and the stability to the particle diameter of the binding aid It can be 2% to 5% in consideration of the sex.

  It is preferable to apply the manufacturing process of this embodiment as follows. A finely powdered solid of binding aid (polymer material) is uniformly mixed with the binding agent. Thereafter, an extender (iron oxide) is added and mixed uniformly. Furthermore, plant seeds are added to this mixture and thoroughly mixed, and then water is added little by little and mixed to be fixed on the surface of the seeds to form a film. However, as long as the film strength, germination characteristics and the like are not affected, the respective steps can be appropriately changed according to the production conditions and the device conditions.

  In the coated plant seeds treated according to this embodiment, the seeds coated at the time of the treatment in the reduced iron powder-gypsum gypsum system or the molybdenum-iron oxide-PVA system contact each other and stick to form lumps and solidify as they are. It has been found that the problem of causing clogging during operation of the planter, which is the next step, does not occur. In addition, it was found that plant seeds treated according to the present embodiment have little aggregation and tend to be easily separated even when consolidated.

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples. The test method used in the following examples is as follows.

  The strength of the coated seed is evaluated as 4 as the standard value of the strength of the coated seed when using a commercial gypsum plaster manufactured by Kubota Co., Ltd., with 5 more strength and 3 when it is somewhat weak And the following was evaluated as 2 or 1. The strength test was conducted by the following simple sensory test three days after formation of the coating film.

  Acupressure test ... push the sample with a fingertip so as to roll it forward slightly. The same finger pressure test was repeated three times using another sample, and the coating condition of each coated seed was visually observed. As a standard material, a sample using Kubota's calcined gypsum is similarly tested. The obtained results were evaluated for strength using the amount of coating chipping, cracking, powder adhering to the fingertip, and the evaluation was less if the sample was less than the standard sample 5, 4 if equivalent, 3 if more, 3 or more It was evaluated as 2.

  Paper testing: The coated seeds, which were slightly wetted with excess water after granulation, were placed on a white ordinary paper and spread by lightly rubbing with a spoon belly. After 3 days, the coated seeds are removed from the paper, and the state of the fine powder adhering to the paper is observed. Empirically, it is known that the higher the strength of the coated seed, the smaller the amount of adhesion. As in the case of the acupressure test, the standard sample was 4 and the evaluation was performed on the same evaluation criteria as the acupressure test.

  In the following examples, the binder refers to calcined gypsum, slaked lime, etc. that chemically change with moisture. In addition, the core material is iron oxide, and the bonding assistant means PVA.

(Experimental example 1)
<Examination of constitution materials>
For a given mass of different binders, the change in strength was investigated when using different reinforcements of different particle sizes. Table 1 shows the results, and the test was performed by the acupressure test. The binder is made of calcined gypsum (estimated as Domestic Chemical Industry Co., Ltd., β-type hemihydrate gypsum) and slaked lime (70% alkali content from Katayanagi Lime Industry Co., Ltd.), and the material is HY-330, which has a small particle size. (Number average particle diameter: about 25 μm, magnetite, HANADA Co., Ltd.) and HY-335 with large particle diameter (number average particle diameter: about 45 μm, magnetite, (HONDA CO., LTD.) Were used. The mixture was pre-mixed with Koshihikari), mixed further with a proper amount of water, finished at a level not adhering to seeds, air-dried for 3 days, and subjected to a strength test. It is mass (kg).

As can be understood from Table 1, the medium-sized filler (HY-330) tends to have a weak strength even when using a binder having a strength different from that of the large-grained medium (HY-335). It was seen. It is presumed that the reason is that if the same mass is used, the smaller the particle diameter, the larger the number of particles and the larger the surface area, and the strength is lowered because the binding material entanglement is not sufficient. Since the purpose of the present invention is to increase the apparent specific gravity of coated seeds as much as possible and to increase the strength, in the following examples, HY-335 having a large particle size is used as a binder.

(Experimental example 2)
<Study of binder>
The mass proportions of the seed meal and the binder were fixed, and the change in strength when the proportion of the extender and the type of the binder were changed was investigated. The results are shown in Table 2.

  The numerical values are the acupressure test, and the values in parentheses are the results when the paper test was performed on the same sample. As shown in Table 2, it can be seen that the commercially available calcined gypsum does not provide sufficient strength as compared to the strength of Kubota Corporation. In addition, slaked lime alone was not strong enough. The method of strength development differs between α-type and β-type in hydration reaction in calcined gypsum and in carbonated reaction in slaked lime. The results show that it is necessary to use slaked lime to improve the strength of the coating.

(Experimental example 3)
<Examination of strength improvement>
In order to increase strength, we considered to make some reaction between slaked lime and inorganic compounds, but sulfuric acid is gypsum, hydrochloric acid is calcium chloride, phosphoric acid is calcium phosphate, etc., and acid is a dangerous substance, and its use is impossible . Although ammonium phosphate used as a fertilizer was experimented, it turned out that a large amount of ammonia gas is generated and can not be put to practical use. Besides, a certain amount of organic acid such as acetic acid, citric acid, humic acid, flubonic acid etc. was added and granulated, and the test was conducted, but there was no improvement in strength, but this is because calcium salt formed It is presumed that is water soluble and that the water resistance is not sufficient.

  Therefore, a composite with a polymer material that can be expected to form a film was examined. This is because mixing the slaked lime with the powder of the polymer material causes only a slight temperature increase due to the hydration reaction. Although various polymer materials are known, in the case of solvent solubility, the harmfulness of the solvent becomes a problem. For this reason, as the polymer material, it is preferable to select from water-permeable polymer materials of water emulsion type.

  An example of the hydrophilic polymer material is an aqueous dispersion type dispersed in water using an emulsifying agent, and an emulsion of styrene acrylic acid copolymer resin (manufactured by Nippon Miracon Sangyo Co., Ltd.) is dried at 10 g, HY- A sample consisting of 3354g and 0.8g of slaked lime mixed with an emulsion solution diluted with water and sprayed while mixing to spread inside, and a sample after granulation and then spraying the emulsion solution on the surface, 2 Types were prepared, and these were dried at room temperature for 3 days to produce coated seeds, and finger pressure strength was examined. These samples did not reach the strength value 4 of the standard sample in the mixed material, and the sample sprayed on the surface was chipped and bald, and the strength value was 3. Furthermore, it can be said that the composite method of this experiment example is not practical for farmers.

  Furthermore, the present inventors examined polyvinyl alcohol (PVA) which is an organic polymer but is solid and acidic, and water-soluble. It has been surprisingly found that the strength of the hydrated lime system is greatly improved. The product of the test was PVA Denkapobar from Denka Co., and three types of B-05S (fine powder), B-24 (granules), and B-24YS (fine powder) were selected from many product numbers. Each characteristic of PVA used in Table 3 is shown.

  The strength change when changing the addition amount of PVA with respect to the fixed mass of slaked lime was tested on the basis of the strength of the calcined gypsum manufactured by Kubota Co., Ltd. in Table 2. As for the test body, the product number of B-17 was newly added to three types in Table 3. B-17 is an intermediate polymer of B-05 and B-24. Table 4 describes the test results.

  As shown in Table 4, when 1% (mass ratio) of PVA is added to slaked lime, the sample is inferior in strength to the calcined gypsum of Kubota Co., Ltd., but when 2% or more of slaked lime is added, any part number of PVA But it turned out that the strength is strong. Also, the strength increased as the degree of polymerization increased, and the strength increased as the amount of addition increased, and the fine powder was better in shape than the granules when mixed with slaked lime. Although the addition amount of PVA is preferably in the range of 2% to 5% in the best embodiment from the viewpoint of practical strength and economy, the addition amount is not particularly limited in the present invention.

Hereinafter, the functional action of the configuration in which PVA is added to the iron oxide powder-slaked lime system will be examined. Here, it is assumed that when water is added to the dry mixture, the moisture adheres uniformly in proportion to the surface area of the particles. What dissolves in water first is presumed to be calcium ion which becomes soluble in water (Ca (OH) ₂ ) in view of its polarity and molecular weight.

This calcium ion reacts with carbon dioxide gas in water to gradually become calcium carbonate. It is presumed that calcic carbonate having a low solubility forms a crystal and forms a structure partially cross-linked to the surface of iron oxide powder or crucible while being mixed with slaked lime.

Here, when the degree of saponification is low when hydrophilic PVA begins to dissolve in water, calcium ions of calcium hydroxide and calcium acetate in PVA are partially saponified to generate calcium acetate. Since the reaction PVA has an increased degree of saponification, the molar ratio of hydroxyl groups increases and the viscosity increases, and the intermolecular force improves the interfacial adhesion with the surface of the iron oxide powder and the crucible, so that the film strength at the time of drying Is considered to improve. Furthermore, the OH group in PVA functions as a proton donor, binds to Ca ²⁺ as a cation exchange resin, and the calcium ion crosslinks adjacent PVA ions to form a crosslinked structure. There is also the possibility of improvement.

  It is presumed that these act in combination and as a result, the strength of the coating film of the eyebrows becomes strong. Moreover, calcium acetate becomes solid when water is removed, and it is presumed that the inside of the film is considerably porous. In addition, since it is not considered that PVA uniformly coats the surface of all solid particles and participates in adhesion between particles, a void is present, which gives a favorable effect on water permeability and germination after seeding. Conceivable.

  That is, when the coated seed meal dried at normal temperature is put into water, water enters the inside by the water pressure of the surface of the film except for cracks and cracks caused by movement, etc., and calcium acetate produced and remains Slaked lime starts to dissolve, and water penetrates further due to osmotic pressure and reaches the surface of the weir.

(Experimental example 4)
<Examination of germination characteristics of coated seeds>
Varying the mixing ratio of dry cocoon and constitution material HY-335, pre-mixing slaked lime as a binder, 2% PVA B-17 as a binding aid, and adding water to a fixed amount of this mixture The mixture was mixed to produce a coated seed cake. Germination was examined using a coated seed meal of the same ratio using Kubota's plaster as a comparative material and an untreated seed meal. Seed meal is Koshihikari from Tochigi. The test period is from August 2 to 20. The average water temperature and the results are shown in Table 5. The numbers in the table are the number of seed meal germinated in 20 grains. The number of coated seeds used as coated seeds was 20 grains each. The seeds used were harvested two years before the test start date, and were stored in a room temperature open system.

  As can be seen from Table 5, the slaked lime-PVA system is found to be faster in sprouting than the calcined gypsum system, PVA is biodegradable, leaves no sulfate group, and has no harmful effect on plants. The above results show that the slaked lime-PVA system has the most favorable effect on germination in the sample.

  The reason for this is that PVA starts to dissolve and water reaches the surface of the pod as a whole relatively quickly, so that germination is also promoted. According to reports of use of general farmers (about 300 cases), it is reported that germination is quicker for several days than the reduced iron powder-gypsum gypsum system. In addition, it agrees with the same report that Niigata Prefectural Rural Public Corporation (2016 Consignment Trial Co., Ltd. Huadean) is similarly reported. The cause of this is that, in the case of calcined gypsum, the film strength is high and the penetration of water is delayed, and the film is difficult to be broken when sprouting, while in the present embodiment, the film is formed with a relatively porous crosslinked structure It is thought that it is because This is one of the features of the present invention. It should be noted that there is room for considering in part the fact that the iron oxide HY-335 used is magnetite and the color is black for the germination promotion property.

(Experimental example 5)
PVA B-17 has a degree of polymerization of about 1700 but a still higher degree of polymerization, and films of different compositions were made using about 2400 of PVA B-24 YS to examine the germination property. The addition rate of PVA B-17 is 2% and 5% with respect to slaked lime, seed: solid material (iron oxide): binder (sludged lime) = 10: 5: 1, the experiment day is October, and other conditions Was the same as in Experimental Example 4. The results are shown in Table 6.

  In October, the water temperature was low at 15-20 ° C. The strength of the coated seed meal was evaluated as 5 in the case of 2% and 4 and 5%, and the result that the strength was higher than that of Kubota's calcined gypsum system was obtained. Also, as shown in Table 6, the germination date was somewhat late, but the germination was almost completed in 15 days. From this, it is understood that in the present embodiment, even a hard coating of strength evaluation 5 can be provided for practical use.

(Experimental example 6)
Although the present invention uses slaked lime and PVA as a binder, finally slaked lime is carbonated with carbon dioxide gas to become calcium carbonate. Therefore, slaked lime in the film is stored in the state of being mixed with calcium carbonate during the reaction. Therefore, a combination of slaked lime shown in Table 7 and calcium carbonate was used as a binder and granulated, and finger pressure strength was examined. PVA B-24YS was added 3% with respect to the total mass of calcium hydroxide and calcium carbonate. Two types of light calcium carbonate (light carbon) and heavy calcium carbonate (heavy carbon) (provided by Totech Co., Ltd.) were separately tested.

  There was no difference in strength between the light and heavy coals at a finger pressure strength of 5. Moreover, the strength was hardly changed even if the compounding ratio was changed. Therefore, it was found that calcium carbonate can be used as a binder either alone or in combination with slaked lime in terms of strength.

  Further, according to another experiment, when PVA B-24YS was used, the strength was high even when 5% by mass was added to slaked lime, and there was no hindrance to germination, and the effectiveness of the present invention was confirmed. However, when slaked lime and PVA are pre-mixed, the possibility of germination failure may be a problem if uniform mixing due to a defect in the mixer can not be performed or if the concentration is high due to a measurement error. The following experiment was conducted to clarify this point.

Experimental Example 7
(Examination of mixing process)
Test conditions 籾: Constitution material (HY-335): Slaked lime (binding material) = 10: 5: 1
PVA B-24YS each added 6%, 10% to slaked lime
籾 = Niigata Koshihikari (Agricultural-Inst. Agency, Chuo-Nakken sample)
Experiment Jun. 24 6% and 10% B-24YS mixed and mixed and granulated Jun. 26 Acupressure test, strength 5 no problem. Leave at room temperature.
July 16 Some dropped into the water, all sediments No float.
September 18 Drops in water at 28 ° C, all sediments. Continued soaking (300 tablets)
September 21 about 10% germination September 25 All germination.

  In the experiment, it was found that the coating film was formed by giving only the water necessary for granulation by drying and making a coating film after storage for 3 months at normal temperature (30 ° C.) and there was no problem in germination. It was also found to be safe even at high concentrations of PVA.

Experimental Example 8
(Examination of particle size dependency of construction material)
As shown in Table 1, when only slaked lime is used as a binder, HY-330 with a small particle size has weaker strength than HY-335 with a large particle size. It was tested whether the strength increases even if the particle size is small as in HY-330, for example, by adding PVA to slaked lime in the present embodiment. For comparison, Red iron oxide HY-820 (Hanade Co., Ltd.) and HY-330 with the same particle size of 325 mesh (45 μm) mesh pass are used as a body material, and dry: solid material: binder = 10: The mixture was mixed at a mass ratio of 5: 1, 10: 3: 1, 10: 2: 1, granulated while adding water, and after 3 days of normal temperature drying, a finger pressure and a paper surface test were performed. In addition, 3% by mass PVAB-24YS was added and mixed with respect to the mass of slaked lime as a coupling | bonding agent. Table 8 shows the results. The values in parentheses are strength values by paper test.

  As shown in Table 8, it became apparent that the strength of the film formed on the surface of the seeds was significantly increased by using PVA as a bonding aid even if the particle size of the extender was small.

It is thought that the method of transplanting seedbeds and mechanical transplants of rice seedling, which is the main component of conventional rice cultivation methods, will be switched to direct direct seeding of rice seedling with the decrease of the agricultural population and the aging of the population. It contributes as one of the important techniques in that case.

Claims (6)

Producing a mixture comprising a binding agent selected from an extender, a binder and PVA;
Adding plant seeds to the mixture and mixing to produce a second mixture;
Forming a film of the second mixture on the surface of the plant seed by mixing while adding water to the second mixture.   The method according to claim 1, wherein the PVA is a powder having a degree of saponification of 80 mol% to 90 mol%, a degree of polymerization of 500 to 2,500, and a particle size of 250 μm or less.   The method according to claim 1, wherein the PVA forms a coating present at 2% by mass to 10% by mass with respect to the binder.   4. A binder according to any one of the preceding claims, wherein the binder is selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates or mixtures of one, two or three thereof. The manufacturing method described in. The reinforcing material is iron oxide powder selected from the group consisting of Fe ₂ O ₃ , Fe ₃ O ₄ , Fe ₂ O ₃ .H ₂ O, or a mixture of one, two or three thereof, The manufacturing method of any one of Claims 1-4. Iron oxide, alkaline earth metal oxides, hydroxides, carbonates or compounds selected from the group consisting of one, two or three mixtures thereof, and Fe ₂ O ₃ , Fe ₃ O ₄ , Fe A plant seed having a coating comprising iron oxide powder selected from the group consisting of ₂ O ₃ .H ₂ O, or a mixture of one, two or three thereof.