JPH11343190A - Elution time adjusting type coated granular fertilizer, its production, control of eluting suppressing period and cultivation using the fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify the ratio of the initial elution suppressing period of a fertilizer component to the elution period of the component and to stably and freely control the elution suppressing time of a coated granular fertilizer by using a thermoplastic resin as a coating film of the coated granular fertilizer and controlling the water absorption of the resin per specified time to a specified proportion to the weight. SOLUTION: When a fertilizer particle as a core is coated with a coating film to produce a coated granular fertilizer, a thermoplastic resin such as polyethylene, polypropylene, ethylene-propylene copolymer is used for the coating film. These thermoplastic resins may be used in a combination of two or more kinds or in a single state, and the moisture permeation and coating rate of the film are controlled to 0.05 to 2.0% water absorption per 24 hours, preferably 0.05 to 1.0% of its weight, and 1.0 to 20% max. water absorption of its weight. Thereby, the ratio D1/D2 of the initial elution suppressed period (D1) of the fertilizer component to the component elution period (D2) is controlled to >=0.2. Thus, an elution time adjusting type coated granular fertilizer can be produced according to planting conditions of agricultural products or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a timed elution-type coated granular fertilizer, a method for producing the same, a method for controlling the elution control period thereof, and a cultivation method using the fertilizer. More specifically,
The present invention relates to a timed elution-type coated granular fertilizer excellent in an initial elution suppression function, a production method thereof, a method of controlling an elution control period thereof, and a cultivation method using the fertilizer.

[0002]

2. Description of the Related Art Originally, during the cultivation period of a crop or the like, fertilization or the like is performed every time a suitable time comes. That is, at the time of seedling start or seeding in this field, either at the time of transplantation, if the whole amount used during the cultivation period or most of it is fertilized at once, the crop will cause concentration disturbance etc., and it will not be possible to harvest. Cause problems. For this reason, fertilization is usually performed several times during the cultivation period.

[0003] In recent years, for the purpose of only one fertilization, it has been attempted to develop a so-called time-eluting type coated fertilizer in which elution of fertilizer components is suppressed for a certain period after fertilization, and rapid elution starts after a certain period. I have. Typical examples thereof include a coated fertilizer in which core fertilizer particles are coated with a coating composed of a saccharide polymer powder and a resin disclosed in JP-A-6-87684, and a coated fertilizer disclosed in JP-A-4-202278. ,
A first coating layer made of an alkali substance is formed on the surface of the core material fertilizer particles, and a second coating made of a mixture of an olefin polymer and a polymer soluble in an aqueous alkaline solution is formed on the surface of the first coating layer. A first coating layer made of a highly water-swelling substance is formed on the surface of a coated granular fertilizer having a layer formed thereon or a core fertilizer particle disclosed in JP-A-4-202079.
Coated granular fertilizers in which a second coating layer made of an olefin-based polymer is formed on the surface of the coating layer are exemplified.

Examples of the coating include an inorganic coating containing sulfur as an active ingredient and a resin coating containing a resin as an active ingredient. Among these coatings, a coating using a resin has recently attracted attention because it has excellent barrier properties against moisture and water vapor and is suitable for realizing a time-dissolving elution function. Examples of the time-eluting type coated granular fertilizer using the resin coating include JP-A-6-87684 and JP-A-4-20227 mentioned above.
No. 8, JP-A-4-202079 and the like.

As disclosed in Japanese Patent Application Laid-Open No. Hei 7-147819, these time-eluting type coated fertilizers employ a method of cultivating a crop in which the coated fertilizer is fertilized in a nursery box simultaneously with sowing, that is, a so-called nursery box fertilization method. Is going to be transformed.

[0006]

However, conventional time-eluting type coated fertilizers have insufficient or unstable elution suppression during the so-called initial elution suppression period, in which the elution of fertilizer components is suppressed for a certain period after fertilization. It is something.

[0007] When a time-eluting type coated fertilizer in which the elution is not sufficiently suppressed during the initial elution control period is used in the above-mentioned nursery box fertilization method, the amount of fertilizer that can be fertilized simultaneously with sowing is limited in order to avoid concentration disturbance. Problems remain. In addition, when a timed elution-type coated fertilizer with unstable elution control during the initial elution control period is used in the nursery box fertilization method, concentration disturbance of the crop due to excessive elution of the fertilizer components during the initial elution control period is similar to the above. Are frequently encountered.

As described above, in order to put the nursery box fertilizer application method to practical use, it is essential to stabilize the elution control period such as the initial elution suppression period of the time-eluting type coated fertilizer so that it can be controlled more freely. It is an issue.

In view of such problems of the prior art, the present inventors have conducted intensive studies, and as a result, the type of fertilizer, the composition of the coating, the film forming method, and the like have shown that the amount of water absorption per 24 hours of the coated fertilizer and the like. It was discovered that it greatly contributed to the maximum water absorption. Furthermore, based on these findings, studies were repeated to commercialize a timed elution-type coated fertilizer with sufficient and stable elution suppression during the elution control period such as the initial elution inhibition period. By controlling the amount of water absorption and the maximum water absorption per 24 hours of the coated fertilizer within a predetermined range, the elution control is stably and freely controlled during the elution control period such as the initial elution suppression period of the timed elution type coated fertilizer. We have found that we can do this and completed the present invention.

Therefore, an object of the present invention is to control a dissolution control period in which the dissolution control in the dissolution control period such as the initial dissolution suppression period can be stably and freely controlled, and the dissolution control period is controlled by the method. It is an object of the present invention to provide a time-eluting coated granular fertilizer, a method for producing the fertilizer, and a method for cultivating a crop or the like using the fertilizer.

[0011]

Means for Solving the Problems In order to achieve the above object, the present invention provides [1] a combination of two or more kinds of thermoplastic resins used for coating a coated granular fertilizer or one kind thereof for 24 hours. The initial elution suppression period of the fertilizer component (D1) by setting the water absorption amount per weight to 0.05 to 2.0% of its own weight.
A method for controlling the dissolution control period of coated granular fertilizer, wherein the ratio D1 / D2 of the component and the component elution period (D2) is 0.2 or more, and [2] two or more kinds of thermoplastic resins used for coating the coated granular fertilizer The water absorption per 24 hours is set to 0.05 to 2.0% of its own weight by combining or using one of the above, and the coating of the coated granular fertilizer is coated with 1 substance insoluble in the solvent used for the coating liquid. By setting the maximum water absorption to 1.0 to 20% of its own weight by adding one or more species, the ratio D1 between the initial elution suppression period (D1) of the fertilizer component and the component elution period (D2)
The present invention proposes a method for controlling the dissolution control period of the coated granular fertilizer having / D2 of 0.2 or more.

Further, the present invention relates to [3] a time-eluting type coated granular fertilizer having an elution control period controlled by the control method of [1] or [2], and [4] a solvent containing one or two thermoplastic resins. At least one species and one or two substances insoluble in the solvent
A method for producing a time-eluting coated granular fertilizer according to [3], wherein the coating solution is coated on the core fertilizer particles, and a time-eluting method according to [5], wherein the coating liquid is coated on the core fertilizer particles. The present invention proposes a cultivation method using coated granular fertilizer.

Hereinafter, the present invention will be described in detail.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The time-dissolved coated granular fertilizer of the present invention is a capsule-shaped coated granular fertilizer in which core fertilizer particles are coated with a predetermined coating, and the initial dissolution of which is suppressed for a certain period after fertilization. It is a coated granular fertilizer having each elution control period of an elution suppression period and a component elution period in which rapid elution starts after a certain period of time. The elution control period will be described in more detail. The timed elution-type coated granular fertilizer of the present invention is characterized in that the period from fertilization to elution of 10% by weight of the fertilizer component in the core material particles is an initial elution suppression period (D1), 80% from the weight% dissolution date
The coated granular fertilizer in which the ratio D1 / D2 of each elution control period is 0.2 or more, where the period up to the weight% elution day is the component elution period (D2).

When cultivating a crop or the like, the coated granular fertilizer starts to absorb water from the time of fertilization in soil or water, and only when a certain amount of water is absorbed, does the fertilizer component inside the capsule, that is, the fertilizer component of the core material, disappear. It has the function of starting elution. In order to exert the above function, it is important to control conditions such as a water absorption amount per 24 hours, a maximum water absorption amount, an initial elution suppression period, and a component elution period. By controlling these conditions, the above function can be surely exhibited, and the coating component and the core fertilizer component of the coated granular fertilizer are not particularly limited, and any one can be adopted.

Here, the amount of water absorption per 24 hours is the amount of water absorbed by the coated granular fertilizer when the coated granular fertilizer is immersed in water for 24 hours. In addition, when the coated granular fertilizer continues to absorb water, the coating is destroyed at the end, but the water absorption immediately before the coating is destroyed is the maximum water absorption.

As the coating used in the present invention, any of inorganic coatings using sulfur as a coating material and resin coatings using a resin as a coating material can be used. Among these coatings, resin is used as a coating material. The resin coating used is a more preferable coating because it has excellent barrier properties against moisture and water vapor and is suitable for realizing a time-dissolving elution function.

The dissolution initiation mechanism of the time-dissolved coated granular fertilizer in the present invention is not particularly limited as long as the dissolution control period such as the initial dissolution suppression period is stable. I will.

A first example of the elution initiation mechanism is the case of a coated granular fertilizer in which core fertilizer particles are coated with a coating that does not transmit liquid water but only transmits water vapor. This coated granular fertilizer has a capsule formed by a film. When this coated granular fertilizer is put into soil or water,
The volume of the core fertilizer particles increases due to the infiltration of water vapor from the outside of the capsule into the inside. The capsule internal pressure caused by this increase in volume causes a crack in the coating, and then the elution of the core fertilizer component to the outside through the generated crack. The mechanism for increasing the volume of the core fertilizer particles inside the capsule is based on the fact that the water vapor that has entered the inside of the capsule condenses into water, and this water increases the volume of the core fertilizer particles. To facilitate the increase in the volume of the core fertilizer particles, the core fertilizer particles may be prepared by mixing and granulating a water-swellable substance such as bentonite in advance with the fertilizer material, The core fertilizer particles may be prepared by attaching the water-swellable substance to the surface of the fertilizer particles obtained by granulating the material.

A second example of the dissolution initiation mechanism is the case of a coated granular fertilizer utilizing the dissolution of a film by an acid or an alkali. In this coated granular fertilizer, the coating is made of a resin soluble in an acid aqueous solution or an alkaline aqueous solution and an insoluble resin, and has a property of permeating only water vapor without permeating liquid water. On the other hand, the core material fertilizer particles are composed of an acid material or an alkali material,
Particles obtained by mixing and granulating a fertilizer material, or particles obtained by attaching an acid material or an alkali material to the surface of fertilizer particles obtained by granulating a fertilizer material. Here, the acid material and the alkali material are, when dissolved in water, turned into an aqueous acid solution and an aqueous alkali solution, respectively. In the coated granular fertilizer, when the coated granular fertilizer is put into soil or water as in the case of the first example of the elution start mechanism described above, water vapor infiltrates into the capsule. This steam then condenses to water. This water dissolves the acid material or the alkali material to generate an aqueous acid solution or an aqueous alkali solution. The aqueous acid solution or the aqueous alkali solution dissolves a resin that is soluble in the aqueous acid solution or the aqueous alkali solution, which is a constituent material of the coating, and makes the coating porous. This causes elution of the core fertilizer components.

As described above, the time-eluting coated granular fertilizer of the present invention is a coated granular fertilizer in which core fertilizer particles are coated with a predetermined coating, and the initial elution is suppressed for a predetermined period after fertilization. A time-eluting coated granular fertilizer having a period (D1) and a component elution period (D2) in which rapid elution is started after a certain period elapses, and wherein the ratio D1 / D2 of each elution control period is 0.2 or more. It is. In order to express such a timed elution function, it is necessary to control the coated fertilizer as described below. That is, the water absorption per 24 hours of the coated granular fertilizer is 0.05 to 2.0% of its own weight,
Preferably it is 0.05 to 1.0%. And the maximum water absorption is 1.0 to 20% of its own weight, preferably 5.0 to 1%.
8%.

The water absorption per 24 hours is 0.05 of its own weight.
% Is usually when the penetration of water vapor into the inside of the coated granular fertilizer is too slow. In this case, the initial elution suppression period tends to be too long. In order to make the initial elution inhibition period appropriate, that is, to shorten the unduly long initial elution inhibition period, weaken the strength of the coating, increase the amount of the water-swellable substance, or use an acid or alkali material. It is also conceivable to use means such as increasing the amount. But,
Even with such a means, it is difficult to sufficiently control the initial elution suppression period, and D1 / D2 becomes small. Therefore, 2
It is not preferable that the amount of water absorbed per 4 hours is less than 0.05% of its own weight. On the other hand, when the amount of water absorption per 24 hours exceeds 2.0% of its own weight, it is usually the case that the penetration of water vapor into the inside of the coated granular fertilizer is too fast. in this case,
The initial elution suppression period tends to be too short. In order to make the initial elution suppression period an appropriate length, that is, to lengthen the initial elution suppression period, increase the strength of the coating,
It is also conceivable to use means such as reducing the amount of the water-swellable substance or reducing the amount of the acid or alkali material. However, even with such means, it is difficult to sufficiently control the initial elution suppression period, and D1 / D2 becomes small. Therefore, it is not preferable that the water absorption per 24 hours exceeds 2.0% of its own weight.

When the maximum water absorption is less than 1.0% of its own weight, it usually means that the strength of the coating is too weak. In this case, it is not preferable because problems such as breakage of the coating are likely to occur during production, storage, distribution and use of the coated granular fertilizer.
On the other hand, when the maximum water absorption exceeds 20% of its own weight, it is usually a case where the strength of the coating is too strong. In this case, the initial elution suppression period tends to be too long. In order to set the initial elution suppression period to an appropriate length, that is, to shorten the unduly long initial elution suppression period, 2
It is also conceivable to use means such as increasing the amount of water absorption per 4 hours. However, even with such a means, it is difficult to sufficiently control the initial elution suppression period, and D1 / D2
Becomes smaller. Therefore, it is not preferable that the maximum water absorption exceeds 20% of its own weight.

By setting the water absorption and the maximum water absorption per 24 hours within the above ranges, the initial elution suppression period and the like can be easily controlled, and the time-eluting type coated granular fertilizer according to the cultivation conditions of crops and the like. Can be manufactured. For example, when it is desired to minimize the amount of elution in the initial elution suppression period and to make the initial elution suppression period over a long period of time, the maximum water absorption is set within the above range so that the water absorption per 24 hours is reduced within the above range. It may be controlled so as to increase within. Further, if the amount of elution in the initial elution suppression period is suppressed as much as possible, and if it is desired to have a short initial elution suppression period, the maximum water absorption is within the above range so that the water absorption per 24 hours is increased within the above range. What is necessary is just to control so that it may decrease.

The method of controlling the amount of water absorption for increasing or decreasing the amount of water absorption per 24 hours is not particularly limited. However, since the amount of water absorption per 24 hours is determined mainly by the moisture permeability of the coating material in the coating, it is preferable to adjust the moisture permeability of the coating by blending at least two types of coating materials. For example, it is preferable to appropriately mix a coating material having low moisture permeability and a coating material having high moisture permeability to set a desired moisture permeability. Further, the coverage of the coating film also affects the amount of water absorption per 24 hours. Therefore, the water absorption can be controlled by changing the coverage.

As described above, as the coating material used in the present invention, an inorganic coating material using sulfur as a coating material, preferably a resin coating material using a resin as a coating material can be used. It is more preferable to use a thermoplastic resin among the above resins as a coating material from the viewpoint of easily adjusting the moisture permeability of the coating by mixing the materials. As specific examples of the thermoplastic resin, polyethylene, polypropylene, ethylene-propylene copolymer,
Examples thereof include an ethylene-ethyl acrylate copolymer, an ethylene-carbon monoxide copolymer, and a vinylidene chloride-vinyl chloride copolymer.

The coating material used in the present invention is preferably applied as a uniform coating on the surface of the core fertilizer particles. In order to obtain this uniform coating, for example, a mixed solution of a uniform coating material to be a coating solution is obtained by mixing and stirring the coating material and a solvent, and this mixed solution is coated on the surface of the core fertilizer particles. Then, the solvent is volatilized and removed to obtain a coated granular fertilizer.

On the other hand, the maximum water absorption is determined by the strength of the coating or
It depends on the solubility in a predetermined solution such as an aqueous acid solution or aqueous alkali solution. Therefore, the maximum water absorption is mainly determined by the coating material such as resin selected at the time of coating preparation, but when depending on the strength of the coating, various shapes,
Arbitrary maximum water absorption can be adjusted by adding an additive having a particle size to the coating material such as a resin as an auxiliary component. As the auxiliary component additive, for example, a substance insoluble in the solvent used for the coating liquid can be used. Specific examples of this insoluble material include talc, clay, kaolin, bentonite, muscovite, phlogopite, mica-like iron oxide, metal oxide, siliceous, glass, and alkaline earth metal carbonate, sulfate, Flour, starch and the like.

In the case where it depends on the solubility in a predetermined dissolving solution such as an aqueous acid solution or aqueous alkali solution,
It is possible to control the maximum water absorption by adjusting the concentration such as the acid concentration or alkali concentration of the solution, or by changing the mixing ratio of the soluble resin to the solution and the insoluble resin. is there.

The fertilizer particles used as the core material of the coated granular fertilizer of the present invention are not particularly limited as long as they contain a component effective as a fertilizer, that is, the fertilizer material described above. Specific examples of these core fertilizer particles include one or two kinds.
Fertilizer particles prepared by mixing and granulating at least one fertilizer material,
Fertilizer particles prepared by mixing and granulating seed or two or more fertilizer materials with one or more pesticidal active ingredients such as insecticides, fungicides, herbicides, etc. One or more fertilizers Material and one or more bentonite, zeolite, talc, clay, fertilizer particles prepared by mixing and granulating with an inert carrier such as diatomaceous earth, and one or more fertilizer materials, One or more pesticides, fungicides, herbicides and other pesticide active ingredients such as one or more, and one or more kinds of inert carriers such as bentonite, zeolite, talc, clay, and diatomaceous earth are mixed and granulated. Fertilizer particles prepared by the above method. Further, prior to coating the surface of the fertilizer particles with the above-mentioned coating, fertilizer particles pre-coated with a resin or an inorganic substance can also be used as the core fertilizer particles of the present invention. Further, in the case of utilizing the dissolution of a film by an acid or an alkali as an elution initiation mechanism, particles obtained by mixing an acid material or an alkali material such as oxalic acid, sodium carbonate and slaked lime with the material of the fertilizer particles, or For example, particles obtained by granulating the material of the fertilizer particles and having the acid material or the alkali material adhered to the surface of the fertilizer particles can be used.

Specific examples of the fertilizer material include ammonium sulfate, salt ammonium,
Water-soluble fertilizers such as ammonium nitrate, urea, potassium chloride, sulfuric acid potassium, nitric acid potassium, sodium nitrate, ammonium phosphate, potassium phosphate and lime phosphate, chelated iron, iron oxide, iron chloride, boric acid, borax, manganese sulfate, manganese chloride , Zinc sulfate, copper sulfate,
Examples include water-soluble trace elements such as sodium molybdate and ammonium molybdate, and poorly water-soluble fertilizers such as OMUP (clotilidene diurea), IBDU (isobutylidene diurea), and oxamide.

The shape of the core fertilizer particles is not particularly limited. However, from the viewpoint of elution accuracy during the initial elution suppression period, it is most preferable that each of the core fertilizer particles has a circularity coefficient of 0.7 or more. % Or more, preferably 99% by weight
As described above, the circularity coefficient is desirably 0.7 or more. The circularity coefficient is a shape coefficient obtained by the following equation, and is a measure for the degree of circularity of a particle.

[0033]

## EQU1 ## Circularity coefficient = 4.pi..times. (Projected area of particle) / (length of contour of particle projected view) ( ² ) When the particle shape is a perfect perfect circle, the circularity coefficient is 1.0 and the particle shape is The circularity coefficient decreases as the shape deviates from a perfect circle. Core fertilizer particles with a circularity coefficient of 0.7 or more,
If the content is less than 90% by weight, it is difficult to obtain a uniform coating on the surface of the core fertilizer particles, which is not preferable. In addition,
The ratio of the core material fertilizer particles having a circularity coefficient of 0.7 or more is hereinafter abbreviated as “circularity (unit:% by weight)”.

The core fertilizer particles can be prepared by granulating a mixture containing the fertilizer material. As a granulation method for obtaining the core material fertilizer particles, a granulation method such as a tumbling granulation method, an extrusion method, a compression granulation method, a crushing granulation method, and a jet granulation method can be used. However, when using a granulation method such as an extrusion method, a compression granulation method, and a crushing granulation method, the obtained particles are likely to have a distorted shape. It is preferable to perform a rounding process using a sizing machine or the like to further increase the circularity coefficient.

The time-eluting coated granular fertilizer of the present invention can be obtained by coating the core fertilizer particles prepared as described above with a coating. The method of coating the core fertilizer particles with the coating is not limited. For example, it is possible to coat the core fertilizer particles with the coating using a device or the like shown in the schematic diagram of FIG. it can.

Hereinafter, a method of coating a core fertilizer particle with a coating will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a jet tower, which blows hot air from a lower portion to an upper portion. The air to be heated is blower 10
From the jet tower 1 through the orifice flow meter 9 and heated by the heat exchanger 8 to generate hot air.
Let it flow inside. The hot air that has passed through the jet tower 1 from the lower part to the upper part is discharged from the exhaust gas outlet 3. This exhaust gas is returned to the blower 10 again, passes through the orifice flow meter 9 and the heat exchanger 8, flows into the jet tower 1 from the bottom of the jet tower 1, and circulates hot air through the jet tower 1. Into the jet tower 1 in which the hot air is circulating, the core material fertilizer particles 5 are introduced from the core material fertilizer particle inlet 2 installed on the side surface of the jet tower 1,
Spout. The temperature T1 and T2 of the hot air are measured by thermometers 13 and 14 installed above the inlet of the hot air from the heat exchanger 8 to the jet tower 1, that is, at the lower part of the jet tower 1 and at the center of the jet tower 1, respectively. Measure using The flow rate and temperature of the hot air can be appropriately adjusted according to the type and size of the core material fertilizer particles, and the type of the coating material. Usually, the flow rate of the hot air is 0.1 to 100 m in linear flow velocity. The temperature of the hot air at a temperature T1 of the thermometer 13 is preferably room temperature to 200 ° C./sec.

In FIG. 1, reference numeral 11 denotes a dissolving tank.
In 1, the coating solution and the solvent are mixed and stirred to obtain a uniform solution 12 of the coating material, which is a uniform coating material. The concentration of the coating material in the mixed solution 12, that is, the concentration of the coating solution, can be appropriately adjusted depending on the type of the coating material and the solvent, the temperature of the mixed solution 12, and the like.
A concentration of 0% is preferred. The solvent is not particularly limited as long as the coating material such as resin is easily dissolved, the coating material as an auxiliary component such as talc and flour and the material used for the core material are hardly dissolved and easily volatilized. However, toluene, xylene, tetrachloroethylene, kerosene and the like are preferable from the viewpoint of easy handling.

As described above, it is preferable to control the moisture permeability of the coating by mixing at least two types of coating materials in the coating of the time-eluting coated granular fertilizer of the present invention. The method of blending at least two types of coating materials is not particularly limited as long as the elution control period such as the initial elution suppression period is stable, but two specific examples will be given below.

As a first example of a method of blending at least two kinds of coating materials, a case where all kinds of coating materials to be used are mixed and stirred with a solvent in a dissolving tank to obtain one kind of mixed solution. be able to. When this one kind of mixed solution is used as a coating solution, a time-eluting type coated granular fertilizer coated with one layer of coating is obtained.

As a second example of a method of compounding at least two types of coating materials, all types of coating materials to be used are divided into one type or two or more types, and the divided coating materials are individually dissolved. There may be mentioned a case where two or more kinds of mixed solution for each divided coating material to be a coating solution are obtained by mixing and stirring with a solvent in a tank.
When a mixed solution of two or more of these is used as a coating solution, a time-eluting coated granular fertilizer coated with two or more layers is obtained. However, in consideration of the complexity of the coating operation for forming such two or more coating films and the cost of capital investment for manufacturing equipment, etc., it is preferable that the coating film has one layer.

Next, the mixed solution 12 is fed by the pump 6 and sprayed and sprayed from the spray nozzle 4 installed at the lower part of the jet tower 1 onto the core fertilizer particles 5 in the jet. In feeding the mixed solution 12, the dissolution tank 11
And the piping from the dissolution tank 11 to the spray nozzle 4 has a double structure,
That is, it is desirable to keep the temperature of the mixed solution 12 at 50 ° C. or higher, more preferably at 80 ° C. or higher, by warming or heating.

In spraying the mixed solution 12 onto the core fertilizer particles 5, the operating conditions such as temperature and time can be appropriately adjusted according to the type of fertilizer material, coating material, solvent and the like. Usually, it is preferable to carry out under the following conditions. That is, spraying of the mixed solution 12 onto the core material fertilizer particles 5 is started when the hot air temperature near the core material fertilizer particles in the jet in the jet tower 1 reaches 50 to 200 ° C. by the thermometer 14. After spraying for 0.2 to 200 minutes, the spraying is stopped and the jet of fertilizer particles is continued to dry for 0.2 to 200 minutes to obtain a coated granular fertilizer. The resulting coated granular fertilizer is
The water is discharged from a discharge port 7 provided at the bottom of the jet tower 1. In addition, when covering the core material fertilizer particles 5 with two layers of coating,
After performing the spraying treatment of the coating liquid of the first layer, the spraying treatment of the coating liquid of the second layer can perform the two-layer coating.

The time-eluting type coated granular fertilizer of the present invention as described above is a fertilizer having extremely excellent performance as a time-eluting type coated granular fertilizer particularly used in a cultivation method such as a nursery box fertilization method.

Hereinafter, a cultivation method using the time-eluting type coated granular fertilizer of the present invention will be described with reference to a nursery box fertilization method and the like.

Originally, during the cultivation period of crops and the like, fertilization and spraying of pesticides are performed at appropriate times, and fertilization and pesticides are performed at the same time at the start of seedling raising or at the time of seeding and transplanting to the main field. When spraying or the like is performed, there is a problem that concentration failure of agricultural crops often occurs due to excessive fertilization. In order to solve such problems, the development of coated fertilizers has been promoted, but in these coated fertilizers, elution suppression of fertilizer components and the like during the initial elution suppression period is insufficient or unstable. . Therefore, even when these coated fertilizers are used, fertilization and the like cannot be performed safely at the same time at the start of seedling raising or at the time of sowing or transplanting to the main field.

In contrast to these conventional methods, in the case of the cultivation method using the time-eluting coated granular fertilizer of the present invention, as described above, the elution suppression of the fertilizer components during the initial elution suppression period is as follows. It is sufficient and stable.
Therefore, when using the coated granular fertilizer of the present invention, it is possible to safely apply the whole amount or most of the amount applied during the cultivation period at the start of seedling raising or at the time of sowing in the field, at the time of transplanting. .

Time-eluting coated granular fertilizers are classified according to the function represented by the elution pattern of fertilizer components and the like and the length of the initial elution suppression period, that is, the timed elution function, and the fertilizer components. With respect to such a time-eluting type coated granular fertilizer, the time-eluting type coated granular fertilizer of the present invention which is applied to a nursery box or a main field may be used alone or in combination of two or more types. It is.

The time-dissolving type coated granular fertilizer of the present invention is not limited at the time of application, but is preferably applied at the beginning of the cultivation period of a crop or the like. It is preferably applied to a nursery container such as a seedling or a nursery pot, or simultaneously at the time of sowing or transplanting to the main field.

The crops used in the cultivation method of the present invention are not limited. For example, leaf vegetables such as cabbage, lettuce and spinach, root vegetables such as radish and carrot, fruit vegetables such as tomato, cucumber and pumpkin, and wheat. Kind,
It can be used for cultivation of corn, potatoes, beans, industrial crops, flowers and the like.

[0051]

EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention should not be limited by these examples. In the following examples, "%" is "% by weight" unless otherwise specified.

Each physical property value was measured by the following method.

Water absorption per 24 hours and maximum water absorption:
1.0 g of the coated granular fertilizer sample is immersed in 50 ml of water at 25 ° C., and after 24 hours, the sample is extracted from the water, and the moisture adhering to the surface of the coating film is sufficiently wiped off with water absorbing paper or the like, and then weighed. This weight increase is the amount of water absorption per 24 hours. Next, this sample was immersed again in 50 ml of new water at 25 ° C., and after a further 24 hours, that is, for a sample after a lapse of 48 hours, the measurement was performed in the same manner as the sample after the lapse of 24 hours. 48
Determine the water absorption per hour. When such an operation is repeated, the coating of the coated granular fertilizer sample is broken, and the weight increase ends. The amount of water absorption immediately before the end of the weight increase has a maximum value. This maximum amount of water absorption is the maximum water absorption.

Circularity coefficient: PIAS- manufactured by Pierce Co., Ltd.
It measured using the measuring device IV.

Synthesis Examples 1 to 11 In preparing core material fertilizer particle samples, core materials such as fertilizer materials were granulated using the types and granulation methods shown in Table 1, and each sample A shown in Table 1 was prepared. ~ C was obtained. In addition,
For sample B shown in Table 1, the granular raw material was supplied to a rotating disk type granulator and sized. Circularity coefficients and the like of the obtained core fertilizer particle samples A to C were measured, and the results are shown in Table 1.

Next, the core fertilizer particle sample prepared as described above was coated with a coating under the conditions shown below and in Tables 2 and 3 using the coating apparatus shown in the schematic diagram of FIG. 2 and coated granular fertilizer samples 1 to 11 shown in Table 3
I got

Here, the coverage is the ratio of the weight (b) of the coating to the coated granular fertilizer, where the sum of the weight (a) of the core fertilizer particles and the weight (b) of the coating is 100% by weight.
It is a value obtained by the formula [b × 100 / (a + b)].

[0058]

[Table 1] * 1 Jet granulation with a jet granulator * 2 Smoothing of granular raw materials with a rotating disk type granulator (made by Fuji Paudal, Malmerizer QJ400) * 3 Rolling granulation with a pan granulator * 4 Percentage of core fertilizer particles with a circularity coefficient of 0.7 or more

[0059]

[Table 2] * 1 PE: low density polyethylene, melting point 110 ° C, MFR = 7 (test temperature 190 ° C, test load 2.16 kgf) * 2 EEA: copolymer with ethylene / ethyl acrylate, ethyl acrylate content 19%, MFR = 5 (test temperature 190 ° C, test load 2.16 kgf) * 3 PCL: polycaprolactone, molecular weight 10,000, melting point 60 ° C * 4 Rubber: styrene / isoprene copolymer, styrene: isoprene = 14:86, MFR = 9 (test Temperature 200 ° C, Test load 5kgf) * 5 The number for each coating material indicates parts by weight * 6 Coverage: 100% by weight of sum of weight (a) of core fertilizer particles and weight (b) of coating The ratio of the weight (b) of the coating to the coated granular fertilizer, that is, the value obtained by the formula [b × 100 / (a + b)] * 7 D1: Initial elution inhibition period * 8 D2: Minute elution period

[0060]

[Table 3] * 1 PE: Low density polyethylene, melting point 110 ° C, MFR = 7 (test temperature 190 ° C, test load 2.16kgf) * 2 PCL: polycaprolactone, molecular weight 10,000, melting point 60 ° C * 3 Rubber: styrene / isoprene copolymer Styrene: isoprene = 14: 86, MFR = 9 (test temperature 200 ° C., test load 5 kgf) * 4 Numbers for each coating material indicate parts by weight * 5 Coverage: weight of core fertilizer particles (a) The ratio of the weight of the coating (b) to the coated granular fertilizer, where the sum of the weight of the coating and the weight of the coating (b) is 100% by weight, that is, the value obtained by the formula [b × 100 / (a + b)] * 6 D1: Initial elution Suppression period * 7 D2: Component elution period The jet tower 1 in FIG. 1 has a tower diameter of 250 mm and a height of 2000 m.
m, an air outlet diameter of 50 mm, and a spout tower having a cone angle of 50 degrees.

The hot air blown from the blower 10 and heated by the heat exchanger 8 was circulated from the lower part to the upper part in the jet tower 1. At this time, the flow rate of hot air and the temperature T1 are:
Each was measured by the orifice flow meter 9 and the thermometer 13, and the measured values were 4 m ³ / min and 130 ± 2, respectively.
° C.

In the jet tower 1 in which the hot air is circulated, core fertilizer particle samples A to C shown in Tables 1 to 3 (in FIG. 10 kg was injected from the core fertilizer particle input port 2 installed on the side surface of, and jetted.

On the other hand, in the dissolution tank 11, a coating solution, that is, a mixed solution 12 was prepared by using the coating materials shown in Tables 2 and 3 and toluene as a solvent, and a coating material concentration of 1.5.
A homogeneous coating solution of weight% was obtained.

The coating liquid was sent by a pump 6 and flowed at a flow rate of 0.1 kg from a spray nozzle 4 which was a 0.8-mm full-con type one-fluid nozzle installed at the lower part of the jet tower 1.
The coating liquid sent at a rate of / min is sprayed and sprayed on the core material fertilizer particle sample in the jet. The coating solution temperature is 80
Although the temperature was not less than 0 ° C., while feeding the coating liquid, the temperature of the coating liquid was kept at 80 ° C. or less by keeping the temperature of the pipes or heating. Here, the coating liquid temperature was measured in a pipe near the spray nozzle 4.

The coating liquid was sprayed onto the core fertilizer particle sample in the jet stream in the jet tower 1 by measuring the hot air temperature T2 near the core fertilizer particle sample with the thermometer 14 as shown in Tables 2 and 3. And spraying was performed so as to have the coverage shown in Tables 2 and 3, then the spraying was stopped, and the jet of the fertilizer particles was dried continuously, and the coated granular fertilizer samples 1 to 3 were dried.
11 was obtained.

For the obtained coated granular fertilizer samples 1 to 11, the water absorption and the maximum water absorption per 24 hours were measured, and the results are shown in Tables 2 and 3.

Test Examples 1 to 7 Coated granular fertilizer samples 1 to 7 obtained in Synthesis Examples 1 to 11
Each 1.0 g was immersed in 50 ml of water at 25 ° C. and allowed to stand at the same temperature. After a lapse of a predetermined period from the start of immersion, the coated granular fertilizer sample was withdrawn from the water, and the amount of the fertilizer component eluted from the sample into the water was measured. Next, the sample was immersed again in 50 ml of fresh water at 25 ° C., and allowed to stand at the same temperature. After a lapse of a predetermined period, the amount of the fertilizer component eluted from the sample into the water during the subsequent predetermined period was measured by the same operation as before. The above operation is repeated, and the total value of the predetermined period, that is, the immersion period is obtained in units of days,
Cumulative values of the amount of fertilizer components eluted into water from the sample during the immersion period were obtained, and the relationship between these accumulated values was represented on a graph to create an immersion period-elution amount curve. FIG. 2 shows the immersion period-elution amount curves prepared for the coated granular fertilizer samples 1 and 3 among these curves.

From the immersion period-elution amount curve, the initial leaching inhibition period (D) was determined by reading the immersion period until 10% of the fertilizer component of the coated granular fertilizer sample was eluted.
1) was determined. Similarly, the component elution period (D2) was determined by reading the immersion period until 80% of the fertilizer component of the coated granular fertilizer sample eluted from the immersion period-elution amount curve. D1 / D2 was determined from the initial elution suppression period and the component elution period. Table 2 shows the obtained initial elution suppression period, component elution period, and D1 / D2.

Comparative Test Examples 1 to 4 Tests were performed in the same manner as in Test Examples 1 to 7 except that coated granular fertilizer samples 8 to 11 obtained in Synthesis Examples 1 to 11 were used as coated granular fertilizer samples. 3 and FIG. 2 were obtained.

From the test results shown in Table 2, with respect to the coated granular fertilizer samples 1 to 7, the water absorption per 24 hours was 0.05 to 2.0% of its own weight, and the maximum water absorption was Is 1.0 to 20% of its own weight. Moreover,
Each of these coated granular fertilizer samples 1 to 7 had a sufficiently long initial elution inhibition period of 20 days or more, and the ratio of the initial elution inhibition period to the component elution period, ie, D1 / D.
2 was also 0.2 or more, and it was recognized that it was suitable as a time-eluting type coated granular fertilizer.

In contrast to the coated granular fertilizer samples 1 to 7 described above, the coated granular fertilizer samples 8 to 11 show that at least one of the water absorption per 24 hours or the maximum water absorption was determined from the test results shown in Table 3. Therefore, it can be said that it is not suitable as a time-eluting type coated granular fertilizer. Therefore, even if the initial elution inhibition period is as short as less than 20 days, or even if the initial elution inhibition period is sufficiently long as at least 20 days, the above D
When 1 / D2 is less than 0.2, it becomes unsuitable as a time-eluting coated granular fertilizer.

More specifically, for example, for the coated granular fertilizer sample 8, the amount of the inert carrier such as talc and flour used in the coating material coated on the core fertilizer particles was reduced to a total of 35%, and the permeability was reduced. The amount of polyethylene, which is a material with low humidity, was increased to 65%. As a result, the maximum water absorption was 8.2%, which was in the range of 1.0 to 20%, but the water absorption per 24 hours was 0.03% and 0.05%.
Became less than low. This coated granular fertilizer sample 8
Is as long as 520 days, and D1 /
D2 was 0.16 and less than 0.2, which proved to be unsuitable as a time-eluting coated granular fertilizer.

In the coated granular fertilizer sample 9, the amount of polycaprolactone, which is a material having high moisture permeability, was used as the coating material to be coated on the core fertilizer particles, as compared with the coated granular fertilizer sample 6. Further, for the coated granular fertilizer sample 9, the amount of polyethylene, which is a material having low moisture permeability, is determined by the amount of the coated granular fertilizer sample 6.
Less than in the case of As a result, the maximum water absorption was 3.5%, which was in the range of 1.0 to 20%.
The water absorption per 24 hours was 2.7%, exceeding 2.0%, which was unreasonably high. The initial elution suppression period for the coated granular fertilizer sample 9 was as short as 6 days, and D1 / D
2 was less than 0.14 and less than 0.2, which proved to be unsuitable as a timed elution-type coated granular fertilizer.

Next, for the coated granular fertilizer sample 10, a rubber material of a copolymer of styrene and isoprene, which is a material having high strength and high moisture permeability, is used as a coating material for coating the core fertilizer particles. The amount used was larger than in the case of coated granular fertilizer sample 7. Further, in the coated granular fertilizer sample 9, the amount of talc used as an inert carrier was reduced as compared with the case of the coated granular fertilizer sample 7. As a result, although the maximum water absorption was slightly increased to 12.3%, it was within the range of 1.0 to 20%, but the water absorption per 24 hours was 2.3% and 2.0%. It was unreasonably high. The initial dissolution inhibition period of this coated granular fertilizer sample 10 was as short as 12 days, and D1 / D2 was 0.18 and less than 0.2, which proved to be unsuitable as a time-dissolved coated granular fertilizer.

On the other hand, in the case of the coated granular fertilizer sample 11, the amount of the rubber material of the copolymer of styrene and isoprene used in the case of the coated granular fertilizer sample 10 was further increased. Under these conditions, the strength of the coating is too strong, that is, the maximum water absorption becomes too large.
It is necessary to use means such as increasing the amount of water absorption per 4 hours. Therefore, coated granular fertilizer sample 11 was prepared without using polyethylene which is a material having low moisture permeability.
As a result, the maximum water absorption is still unreasonably high, exceeding 23% and 20%, and the water absorption per 24 hours is also 6.
It exceeded 2% and 2.0% and was unduly high. The initial dissolution inhibition period of the coated granular fertilizer sample 11 was as short as 4 days, and D1 / D2 was 0.17 and less than 0.2, which proved to be unsuitable as a time-dissolved coated granular fertilizer.

Example 1 From the test results shown in Table 2, with respect to coated granular fertilizer samples 1 and 3, each sample showed that the water absorption per 24 hours was 0.11% and 0.17% of its own weight, respectively. In addition, the maximum water absorption is 7.4% and 6.1% of its own weight, and it can be said that it is suitable as a timed elution-type coated granular fertilizer. Further, for these coated granular fertilizer samples 1 and 3, the immersion period-elution amount curve is as shown in FIG.

Therefore, these coated granular fertilizer samples 1
And 3, the mixing ratio is 95: 5, 90:10,...
The composition was changed every 5 units at 5:95 and calculated from the respective composition ratios to draw 19 immersion period-elution amount curves. As an example of them, FIG. 3 shows an immersion period-elution amount curve when the mixing ratio of the coated granular fertilizer samples 1 and 3 is 60:40.

The nutrient demand curve (nutrient absorption pattern) of the cucumber (variety: Aso midori) in the open-field cultivation of the cucumber (variety: Aso midori) in the open space cultivation in Minamata City, Kumamoto, from the sowing to the harvesting, It was determined from the measured soil nutrient supply curve during the cultivation period (soil nutrient supply at each stage) and the nutrient absorption curve of the cucumber (nutrient absorption at each stage).
The basic data used to obtain these curves is the prototype data of the same crop conducted in the same area last year. The nutrient demand curve of the cucumber obtained in the previous year obtained in this manner was determined by comparing the above-mentioned coated granular fertilizer samples 1 and 3 with the mixing ratio of 60:
FIG. 3 shows an immersion period-elution amount curve for the case of 40,
The shapes and the like of these curves were compared. However,
The nutrient demand curve shows the temperature change (18 to 32) during the cultivation period.
(In the range of about ° C).
Although it does not exactly match the condition of 25 ° C. constant during the measurement of the elution curve, the average temperature during the cultivation period in the nutrient demand curve was approximately 25 ° C., so that both conditions can be treated almost equally. it can.

A comparison of the two curves shows that the initial elution of both curves is extremely low and is very similar. As described above, from the test results shown in Table 2, with regard to the coated granular fertilizer samples 1 and 3, each of the samples had a water absorption amount per 24 hours of 0.11 of its own weight.
% And 0.17%, and the maximum water absorption is also 7% of its own weight.
4% and 6.1%, which can be said to be suitable as the time-eluting coated granular fertilizer. However, from the comparison in FIG. 3, the coated granular fertilizer samples 1 and 3 are used alone as the time-eluting coated granular fertilizer. It was presumed that it was more suitable to use the coated fertilizer samples 1 and 3 as the mixed fertilizer A at a mixing ratio of 60:40 than to perform the mixing.

A cucumber cultivation test using the compounded fertilizer A was performed in the following manner in a field in Fukuro (place name), Minamata City, Kumamoto Prefecture.

For 100 ml of the seedling culture soil containing no fertilizer prepared beforehand, 10 mg of a phosphorus component (P ₂ O ₅ component, hereinafter abbreviated as P) and a potassium component (K ₂ O) were used as fertilizers for raising seedlings. Component, hereinafter abbreviated as K.) Nitrogen component (N component, hereinafter abbreviated as N) present in mixed fertilizer A (400 ml) mixed with 10 mg of the seedling raising soil material (8.33 g).
(N per 15 a of the field is equivalent to 15 kg) The amount of the compounded fertilizer A is thoroughly stirred and filled into a vinyl pot of 10 cm in diameter, and then one cucumber seed (variety: Aso midori) is sown. The seedling culture was further covered thereon, and seedlings were grown in a plastic pot from April 26 to May 6. After raising seedlings in a plastic pot,
The seedlings were transplanted to a field at a density of 1800 plants / 10a, and cultivation in the field was started. After that, harvesting of the main stem started on July 6, and harvesting of side branches started on July 26.
Harvested on day 0, the cultivation was completed.

The seedlings are transplanted to a field, and P: 14% and K: 1 as fertilizer components between the time when the seedlings are planted in the field and before the harvest.
The advanced chemical fertilizer containing 4% was fertilized in four times.
The amount of fertilization is as follows. In four fertilizations, PK is per field 10a,
It was adjusted to be 15kg-15kg.

Comparative Example 1 100 ml of seedling cultivation soil containing no fertilizer prepared beforehand was used as a fertilizer for raising seedlings, N: 10 m
g, P: 10 mg, K: 10 mg, and the seedling cultivation material was mixed in a 10 cm diameter type plastic pot for 400 m.
After filling, 1 seed of cucumber seed (variety: Aso midori) was sown, and the seedling cultivation soil was covered thereon.
Seedlings were raised in plastic pots from 6th to 6th May.
After raising the seedlings in the plastic pot, place the seedlings in the field
The plants were transplanted at a density of 800 plants / 10a, and cultivation in the field was started. After that, harvesting of the main stem was started on July 6, harvesting of side branches was started on July 26, and harvesting was completed on September 20, completing the cultivation.

The seedlings were transplanted to a field, and N: 14% and P: 1 were used as fertilizer components between the time when the seedlings were planted in the field and before the harvest.
Advanced chemical fertilizer containing 4% and K: 14% was fertilized in four times. The amount of fertilization was adjusted so that NPK was 15 kg-15 kg-15 kg per field 10 a in four fertilizations.

As described above, in the cultivation test of Comparative Example 1, N topping was performed, and Example 1 and Comparative Example 2 described later were used.
In the cultivation test, the cucumber cultivation test was performed without performing N topdressing.

Comparative Example 2 From the test results shown in Table 3, with respect to coated granular fertilizer samples 10 and 11, the water absorption per 24 hours was 2.3% and 6.2% of their own weight, respectively, and the maximum water absorption was It is 12.3% and 23% of its own weight, and at least one of the water absorption per 24 hours or the maximum water absorption is out of the range of the present invention, and it can be said that it is unsuitable as a time-eluting coated granular fertilizer. On the other hand, these coated granular fertilizer samples 10 and 1
With respect to No. 1, the immersion period-elution amount curve is as shown in FIG.

The coated granular fertilizer sample 10
Period in the case of the compound fertilizer B having the compounding ratio of 80:20 and the elution amount curve, the immersion period in the case of the compound fertilizer A having the compounding ratio of the coated granular fertilizer samples 1 and 3 described above of 60:40. The elution curve and the cucumber nutrient requirement curve of the previous year are shown in FIG. 3, and the shapes and the like of these curves were compared.

From the comparison of these curves, the immersion period-elution amount curve in the case of the compound fertilizer A and the above-mentioned cucumber nutrient requirement curve in the previous year are extremely similar as described above. The immersion period-elution amount curve for fertilizer B is
It can be seen that the suppression of the initial elution is insufficient, which is clearly different from the former two curves. As described above, from the test results shown in Table 3, with respect to the coated granular fertilizer samples 10 and 11, the water absorption per 24 hours was 2.3% and 6.2% of their own weight, respectively, and the maximum water absorption was their own weight. Of 1
It is 2.3% and 23%, and at least either the water absorption per 24 hours or the maximum water absorption is out of the range of the present invention, and it can be said that it is unsuitable as a time-eluting coated granular fertilizer. From the comparison, the coated granular fertilizer samples 10 and 11 were used in the same manner as when the coated granular fertilizer samples 10 and 11 were used alone as the time-eluting type coated granular fertilizer.
It was presumed that the case where the compounding ratio of 1 was used as the compounding fertilizer B of 80:20 was also unsuitable.

A cucumber cultivation test using the compounded fertilizer B in a field in Fukuro (place name) in Minamata-shi, Kumamoto was performed in the same manner as in Example 1 except that compounded fertilizer B was used instead of compounded fertilizer A. went.

As a result of the cultivation test, no germination occurred in the cultivation test of Comparative Example 2 (germination rate: 0%). From this, it is clear that excessive elution of the fertilizer component in the early growth stage is the cause. Compound fertilizer B in FIG.
As is clear from the elution curve, the initial elution of the compound fertilizer B was not sufficiently suppressed, and it was found that this excessive elution caused concentration disturbance to cucumber seeds.

On the other hand, in the cultivation test of Example 1, the germination rate was 97%, which was almost the same as the germination rate of 98% in the cultivation test of Comparative Example 1 in which N was fertilized. there were. Further, the harvest index in the cultivation test of Example 1 was 102, and the yield was not inferior to the harvest index of 100 in the cultivation test of Comparative Example 1 in which N was fertilized.

From the viewpoint of work, the following can be said. Since the work in the nursery box is a work in a narrow place called the nursery box, the work of Example 1 and the work of Comparative Example 1 are equivalent in the amount of work. However, since the work in the field is a work in a wide area such as a field, in the first embodiment, since the topdressing of N is not required, the amount of work can be greatly reduced.

[0093]

In the present invention, the water absorption per 24 hours is set to 0.05 to 2.0% of its own weight, or the water absorption per 24 hours is set to 0.05 to 2.0% of its own weight. %
By setting the maximum water absorption to 1.0 to 20% of its own weight, the initial elution inhibition period of the coated granular fertilizer is sufficiently long, and the ratio of the initial elution inhibition period to the component elution period, ie, D1 /
D2 can be 0.2 or more. By such control, a good time-eluting type coated granular fertilizer can be obtained.

Further, the method for cultivating a crop using the time-eluting coated granular fertilizer of the present invention can greatly reduce the labor of the operation and the utilization efficiency of the fertilizer without lowering the germination rate and the yield of the crop. To improve it.

[Brief description of the drawings]

FIG. 1 is a schematic view of a coating apparatus for producing a timed elution-type coated granular fertilizer of the present invention.

FIG. 2: Coated granular fertilizer samples 1, 3, 8, 10 and 1
1 is a graph showing an immersion period-elution amount curve of Example 1.

FIG. 3 is a graph showing a immersion period-elution amount curve of compounded fertilizers A and B, and a cucumber nutrient requirement curve of the previous year described above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spout tower 2 Core material fertilizer particle input port 3 Exhaust gas outlet 4 Spray nozzle 5 Core material fertilizer particle 6 Pump 7 Extraction port 8 Heat exchanger 9 Orifice flow meter 10 Blower 11 Dissolution tank 12 Mixed dissolved solution of coating material 13 Thermometer 14 Thermometer

Claims (5)

[Claims] Claims 1. A combination of two or more kinds of thermoplastic resins used for the coating of coated granular fertilizer, or one kind thereof, having a water absorption per 24 hours of 0.05 to 2.0% of its own weight. The method for controlling the elution control period of the coated granular fertilizer, wherein the ratio D1 / D2 between the initial elution suppression period (D1) and the component elution period (D2) of the fertilizer component is 0.2 or more. 2. A combination of two or more kinds of thermoplastic resins used for the coating of the coated granular fertilizer, or a combination of one or more kinds thereof, so that the water absorption per 24 hours is 0.05 to 2.0% of its own weight, and By adding one or more substances insoluble in the solvent used for the coating liquid to the coating of the coated granular fertilizer to make the maximum water absorption 1.0 to 20% of its own weight, the initial elution suppression period of the fertilizer component Ratio D1 between (D1) and component elution period (D2)
A method for controlling the dissolution control period of coated granular fertilizer wherein / D2 is 0.2 or more. 3. A timed elution-type coated granular fertilizer having an elution control period controlled by the control method according to claim 1 or 2. 4. A solvent is obtained by mixing and dissolving one or more thermoplastic resins and one or more substances insoluble in the solvent in a solvent to obtain a coating solution, and applying the coating solution to core material fertilizer particles. The method for producing a timed elution-type coated granular fertilizer according to claim 3, which is coated. 5. A cultivation method using the time-eluting coated granular fertilizer according to claim 3.