WO2001038261A1

WO2001038261A1 - Coated granular fertilizers of time-programmed elution type, process for producing the same, method for controlling the elution-control time thereof and cultivation method with the use of the fertilizers

Info

Publication number: WO2001038261A1
Application number: PCT/JP1999/006469
Authority: WO
Inventors: Masazumi Uchino
Original assignee: Chisso Corporation
Priority date: 1998-05-29
Filing date: 1999-11-19
Publication date: 2001-05-31
Also published as: JPH11343190A

Abstract

A method for controlling the elution-control time of a coated granular fertilizer which comprises controlling the ratio D1/D2 (wherein D1 stands for the early elution regulatory period of fertilizer components, while D2 stands for the elution time (D2) of the components) to at least 0.2 by using either a combination of two or more thermoplastic resins or one thermoplastic resin in the coating of the coated granular fertilizer to thereby control the water absorption per 24 hours to 0.05 to 2.0% of the own weight thereof, or by further adding to the coating of the coated granular fertilizer one or more substances insoluble in the solvent employed in the coating solution to thereby control the maximum water absorption to 1.0 to 20% of the own weight thereof.

Description

Specification

Time-eluting coated granular fertilizer, its production method, method of controlling its elution control period, and cultivation method using the fertilizer

Field of the invention

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 the function of suppressing initial elution, a production method thereof, a method of controlling the elution control period thereof, and a cultivation method using the fertilizer.

Background of the Invention

Originally, during the cultivation period of crops and the like, fertilization and the like are performed every time the appropriate time comes. In other words, if fertilization is applied to all or most of the amount used during the cultivation period at the start of seedling raising, sowing in this field, or at the time of transplanting, crops will cause concentration disturbances, etc., making it impossible to harvest. Cause problems. For this reason, fertilization is usually performed several times during the cultivation period.

In recent years, to achieve a single fertilization application, the development of so-called time-dissolved coated fertilizers has been attempted, in which the elution of fertilizer components is suppressed for a certain period after fertilization and the elution starts quickly after a certain period. 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, as disclosed in Japanese Patent Application Laid-Open No. 6-87664, A first coating layer composed of an alkaline substance is formed on the surface of the core fertilizer particles disclosed in Japanese Patent No. 0228278, and the olefin polymer and the aqueous solution of the aqueous solution are formed on the surface of the first coating layer. On the other hand, a coated granular fertilizer having a second coating layer formed of a mixture with a soluble polymer, or a highly water-swelling substance on the surface of core material fertilizer particles disclosed in Japanese Patent Application Laid-Open No. H4-22079. A coated granular fertilizer in which a first coating layer made of olefin polymer is formed on the surface of the first coating layer, and a second coating layer made of an olefin polymer is formed on the surface of the first coating layer.

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, the coatings using resin are made of water or water vapor. It has attracted attention recently because of its excellent gas barrier properties and its suitability for realizing a timed elution type elution function. Examples of the time-eluting type coated granular fertilizer using the resin coating include the above-mentioned JP-A-6-87664, JP-A-4-202278, and JP-A-4-4-2. And coated granular fertilizers such as No. 0279. As described in Japanese Patent Application Laid-Open No. 7-147819, these time-dissolving type coated fertilizers are cultivated in a method of cultivating a crop in which the coated fertilizer is fertilized in a nursery box simultaneously with sowing, a so-called nursery box fertilization method. Is to be put to practical use.

However, conventional timed elution-type coated fertilizers have an inadequate 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.

When a timed elution-type coated fertilizer with insufficient elution control during the initial elution control period is used in the above-mentioned nursery box fertilization method, the amount of fertilizer that can be fertilized at the same time as seeding is limited to avoid concentration disturbance. The problem remains. In addition, when a timed elution-type coated fertilizer with unstable elution control during the initial elution suppression period is used in the nursery box fertilization method, as described above, over-elution of fertilizer components during the initial elution suppression period There are problems such as frequent occurrence of density disturbance.

In order for the nursery box fertilizer application method to be practical, it is essential to stabilize the elution control period, such as the initial elution suppression period, of the timed elution type coated fertilizer, and to make it possible to freely control it. is there.

Summary of the Invention

In view of such problems of the conventional technology, 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 been determined to determine the amount of water absorption per 24 hours and the maximum water absorption of the coated fertilizer. We found that it greatly contributed to the quantity. Based on these findings, further studies were conducted to put into practical use a timed elution-type coated fertilizer with sufficient and stable elution control during the elution control period such as the initial elution control 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 performed during the elution control period such as the initial elution suppression period of the timed elution type coated fertilizer. It has been found that can be controlled stably and freely, and the present invention has been completed.

Accordingly, an object of the present invention is to provide a method for controlling a dissolution control period in which the dissolution control during a dissolution control period such as an initial dissolution suppression period can be stably and freely controlled. An object of the present invention is to provide a mold-coated granular fertilizer, a method for producing the fertilizer, and a method for cultivating a crop or the like using the fertilizer.

In order to achieve the above object, the present invention provides

[1] Initialization of fertilizer components by combining two or more types of thermoplastic resin used for the coating of coated granular fertilizer, or by using one type to make the water absorption per 24 hours 0.05 to 2.0% of its own weight A method for controlling the dissolution control period of the coated granular fertilizer in which the ratio D1ZD2 of the dissolution inhibition period (D1) to the component dissolution period (D2) is 0.2 or more, and

(2) Combine two or more of the thermoplastic resins used for the coating of the coated granular fertilizer, or use one of them to set the water absorption per 24 hours to 0.05 to 2.0% of their own weight, and By adding one or more substances insoluble in the solvent used for the coating liquid to the coating and setting the maximum water absorption to 1.0 to 20% of its own weight, the initial elution suppression period (D1) and the elution period of the fertilizer components The present invention proposes a method for controlling the dissolution control period of coated granular fertilizer with the ratio D1 and ZD2 to (D2) 0.2 or more.

Further, the present invention provides

(3) Time-eluting coated granular fertilizer having an elution control period controlled by the control method of (1) or (2),

(4) One or more thermoplastic resins and one or more substances insoluble in the solvent are mixed and dissolved in a solvent to obtain a coating solution, and the coating solution is coated on the core fertilizer particles. (3) production method of time-elution type coated granular fertilizer, and

[5] A cultivation method using the time-eluting coated granular fertilizer of [3] can be proposed.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic diagram of a coating apparatus for producing a time-eluting coated granular fertilizer of the present invention.

FIG. 2 is a graph showing the leaching-per-exposure curves of the coated granular fertilizer samples 1, 3, 8, 10 and 11.

Fig. 3 is a graph showing the elution amount curve of the compound fertilizers A and B during the immersion period and the nutrient demand curve of the aforementioned cucumber in the previous year.

Disclosure of the invention

The timed elution-type 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 elution is suppressed for a certain period after fertilization, and the initial elution suppression period is constant. It is a coated granular fertilizer having each elution control period of the component elution period in which the elution starts immediately after the elapse of the period. The dissolution control period will be described in more detail. The time-dissolved coated granular fertilizer of the present invention is characterized in that the period from fertilization to the elution of 10% by weight of the fertilizer component in the core material particles is the initial dissolution inhibition period (D1). ), When the period from the 10% by weight dissolution to the 80% by weight dissolution is defined as the component dissolution period (D2), the ratio of the respective dissolution control periods D1 ZD2 is 0.2 or more coated granules. Fertilizer.

When cultivating crops, this coated granular fertilizer starts to absorb water when fertilized in soil or water, and elutes the fertilizer component inside the capsule, that is, the fertilizer component of the core material, only when a certain amount of water is absorbed. It has the function of starting. In order to exert the above functions, it is important to control conditions such as water absorption per 24 hours, maximum water absorption, initial elution suppression period, and component elution period. By controlling these conditions, the above function can be surely realized. The coating component of the coated granular fertilizer ゃ the core material fertilizer component is 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, the coated granular fertilizer will break at the end if water absorption is continued, but the maximum 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, a resin is used as a coating material. The coated resin film is a more preferable film because it has excellent barrier properties against moisture and water vapor and is suitable for realizing a time-dissolved 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, but two specific examples will be given below.

A first example of the elution initiation mechanism is a case of a coated granular fertilizer in which core fertilizer particles are coated with a coating that does not transmit liquid water but transmits only water vapor. This coated granular fertilizer has a capsule formed by a coating. When this covered granular fertilizer is placed in soil or water, the volume of 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 cracks in the coating, which in turn causes the core fertilizer components to elute out through the cracks. The mechanism of increasing the volume of the core fertilizer particles inside the capsule is based on the fact that the water vapor that has entered the capsule condenses into water, and the water increases the volume of the core fertilizer particles. In order to easily increase the volume of the core material fertilizer particles, the core material fertilizer particles may be prepared by previously mixing and granulating a water-swelling substance such as bentonite into the fertilizer material. The core fertilizer particles may be prepared by adhering the water swellable substance to the surface of the fertilizer particles obtained by granulating the fertilizer material. As a second example of the elution initiation mechanism, the case of a coated granular fertilizer utilizing the dissolution of a film by an acid or an acid can be mentioned. In the 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 fertilizer particles are particles obtained by mixing and granulating an acid or alkali material and a fertilizer material, or a table of fertilizer particles obtained by granulating a fertilizer material. Particles with an acid or alkali material attached to the surface. Here, the acid material and the alkaline material are, when dissolved in water, an acid aqueous solution and an alkaline aqueous solution, respectively. In the coated granular fertilizer, as in the case of the first example of the elution initiation mechanism described above, when the coated granular fertilizer is put into soil or water, water vapor infiltrates into the capsule. This steam then condenses to water. This water dissolves the acid material or the alkaline material to produce an acid aqueous solution or an alkaline aqueous solution. The acid aqueous solution or the alkaline aqueous solution dissolves a resin soluble in the acid aqueous solution or the aqueous solution of the alkali, which is a constituent material of the coating, and makes the coating porous. This causes elution of the core fertilizer components.o

As described above, the time-eluting type 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 suppression period in which elution is suppressed for a certain period after fertilization ( D1) and a component elution period (D2) in which rapid elution starts after a certain period of time, and a time-eluting type coated granule in which the ratio D1ZD2 of each elution control period is 0.2 or more. Fertilizer. In order to achieve such a timed elution function, it is necessary to control the coated fertilizer as shown below. That is, the coated granular fertilizer has a water absorption per 24 hours of 0.05 to 2.0% of its own weight, and preferably 0.05 to 1.0%. In addition, the maximum water absorption is 1.0 to 20% of its own weight, preferably 5.0 to 18%.

When the water absorption per 24 hours is less than 0.05% of its own weight, it is usually because the penetration of steam 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 water-swellable substances, acid materials or alkalis. It is also conceivable to use means such as increasing the amount of material. Even if such a means is used, it is difficult to sufficiently control the initial elution suppression period, and D 1 ZD 2 becomes small. Therefore, if the water absorption per 24 hours is less than 0.05% of its own weight, it is preferable. Not good. On the other hand, when the water absorption per 24 hours exceeds 2.0% of its own weight, it is usually the case that steam infiltrates into the coated granular fertilizer too quickly. In this case, the initial elution suppression period tends to be too short. To make the initial elution suppression period appropriate, that is, to lengthen the initial elution suppression period, increase the strength of the coating, reduce the amount of water-swellable substances, and reduce the amount of acid or alkali materials. It is also conceivable to use such means. Even if such a method is used, it is difficult to sufficiently control the initial elution suppression period, and D 1 ZD 2 becomes small. Therefore, it is not preferable that the amount of water absorption per 24 hours exceeds 2.50 of its own weight.

When the maximum water absorption is less than 1.0% of its own weight, the strength of the coating is usually too weak. In this case, it is not preferable because problems such as breakage of the coating easily 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 because the strength of the coating is too strong. In this case, the initial elution suppression period tends to be too long. In order to make the initial elution suppression period appropriate, that is, to shorten the unduly long initial elution suppression period, use measures such as increasing the water absorption per 24 hours as described later. Is also conceivable. However, even with such means, it is difficult to sufficiently control the initial elution suppression period, and D 1 Z D 2 becomes small. Therefore, it is not preferable that the maximum water absorption exceeds 20% of its own weight.

By setting the amount of water absorption per 24 hours and the maximum amount of water absorption within each of the above ranges, the initial elution suppression period and the like can be easily controlled, and the time-eluting type coated granular fertilizer suitable for the cultivation conditions of crops and the like can be obtained. Can be manufactured. For example, when it is desired to minimize the amount of elution during 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 so that the water absorption per 24 hours is reduced within the above range. What is necessary is just to control so that it may increase in the said range. When the amount of elution in the initial elution suppression period is to be minimized and the initial elution suppression period is to be short, the maximum water absorption is set to the above value 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 become small in the range.

The method of controlling the water absorption to increase or decrease the water absorption per 24 hours is not particularly limited. However, since the amount of water absorption per 24 hours is mainly determined by the moisture permeability of the coating material in the coating, it is preferable to adjust the moisture permeability of the coating by combining at least two types of coating materials. For example, it is preferable to appropriately mix a film material having low S permeability and a film material having high moisture permeability to set a desired moisture permeability. In addition, the coverage of the coating film also affects the amount of water absorption per 24 hours, so it is possible to control the amount of water absorption 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, and 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 that the moisture permeability of the coating can be easily adjusted by blending the above. Specific examples of the thermoplastic resin include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, ethylene-carbon monoxide copolymer, and vinylidene chloride-vinyl chloride copolymer. Coalescence and the like.

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 a uniform coating, for example, a mixed solution of a uniform coating material serving as a coating solution is obtained by mixing and stirring a coating material and a solvent, and the 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 depends on the strength of the coating or the solubility in a predetermined dissolving solution such as an acid aqueous solution or an alkaline aqueous solution. Therefore, the maximum water absorption is mainly determined by the coating material such as resin selected at the time of coating preparation. However, if it depends on the strength of the coating, the coating material such as resin can be made with additives of various shapes and particle sizes as auxiliary components. Can be adjusted to an arbitrary maximum water absorption. As the auxiliary component additive, for example, a substance insoluble in the solvent used for the coating liquid can be used. Illustrative examples of this insoluble material include talc, cres, wollin, bentonite, muscovite, phlogopite, mica-like iron oxide, metal oxides, siliceous, glass, and alkaline earth metal carbonates. Sulfate, flour, starch, and the like.

In addition, when the solution is dependent on the solubility in a predetermined solution such as an acid aqueous solution or an aqueous solution of an acid, the concentration of the acid or the concentration of the aqueous solution is adjusted, or The maximum water absorption can be controlled by changing the mixing ratio of the soluble resin to the insoluble resin.

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 material fertilizer particles include: , Fertilizer particles prepared by mixing and granulating one or more fertilizer materials, one or more fertilizer materials, and one or more pesticides, fungicides, herbicides, etc. Fertilizer particles prepared by mixing and granulating the active ingredient, one or more fertilizer materials, and one or more types of bentonite, zeolite, talc, clay, geese earth, etc. Fertilizer particles prepared by mixing and granulating a carrier; one or more fertilizer materials; one or more pesticides, fungicides, herbicides, and other pesticidal active ingredients; Species or two or more bentonite, Orai DOO, talc, clay, can be given fertilizer particles or the like prepared by mixing granulated and inert carrier such as Keisou soil. Further, prior to coating the surface of the fertilizer particles with the above-mentioned coating, fertilizer particles preliminarily coated with a resin or an inorganic substance can also be used as the core material fertilizer particles of the present invention. Further, when the dissolution of the film by acid or alkali is used as the elution initiation mechanism, an acid material such as oxalic acid, sodium carbonate, and slaked lime, or an alkaline material is mixed with the material of the fertilizer particles to granulate. Particles obtained by granulating the material of the fertilizer particles or particles obtained by adhering the acid material or the alkaline material to the surface of the fertilizer particles obtained by granulating the material of the fertilizer particles can be used. Specific examples of fertilizer materials include water-soluble fertilizers such as ammonium sulfate, salt and salt, ammonium nitrate, urea, potassium chloride, sulfuric acid, nitric acid, sodium nitrate, ammonium phosphate, potassium phosphate and lime phosphate, chelated iron, and oxides. Water-soluble trace elements such as iron, iron chloride, boric acid, borax, manganese sulfate, manganese chloride, zinc sulfate, copper sulfate, sodium molybdate and ammonium molybdate, as well as OMUP (clotylidenediarea), IBDU (iso Poorly water-soluble fertilizers such as butylidene diurea) and oxamide.

The shape of the core fertilizer particles is not particularly limited. However, from the viewpoint of the elution accuracy during the initial elution control period, it is most preferable that all of the core fertilizer particles have a circularity coefficient of 0.7 or more. It is desirable that the circularity coefficient is not less than 0.7% by weight, preferably not less than 99% by weight, more preferably not less than 90% by weight. The circularity coefficient is a shape factor obtained by the following equation, and is a measure for the degree of circularity of a particle.

Circularity coefficient = 4 7 Γ X (projected area of particle) Z (length of contour of particle projection) ^{2 If the} particle shape is a perfect circle, the circularity coefficient is 1.0, and the particle shape changes from a perfect circle. As it collapses, the circularity coefficient decreases. If the core fertilizer particles having a circularity coefficient of 0.7 or more are less than 90% by weight, it is difficult to obtain a uniform film on the surface of the core fertilizer particles, which is not preferable. The percentage of core fertilizer particles having a circularity coefficient of 0.7 or more is hereinafter abbreviated as “circularity (unit: 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, or a crushing granulation method, the obtained particles are likely to have a distorted shape. Further, it is preferable to further perform a chamfering 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, the method of coating the core fertilizer particles with a device such as the apparatus shown in the schematic diagram of Fig. 1 may be used. I can do it.

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 the bottom to the top. The air to be heated is blown from the blower 10, passes through the orifice flowmeter 9, is heated by the heat exchanger 8 to form hot air, and flows into the jet tower 1 from the bottom of the jet tower c. 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. The 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 in the jet tower 1. The core material fertilizer particles 5 are injected into the jet tower 1 in which the hot air is circulated, from the core material fertilizer particle input port 2 installed on the side surface of the jet tower 1, and jetted. The hot air temperatures T 1 and T 2 are measured by thermometers 1 installed above the inlet of the hot air from the heat exchanger 8 to the jet tower 1, that is, at the bottom of the jet tower 1 and at the center of the jet tower 1. Measure using 3 and 14. The flow rate and temperature of the hot air can be appropriately adjusted according to the type and size of the core fertilizer particles and the type of the coating material, but usually, the flow rate of the hot air is 0.1 to 1 in terms of linear flow velocity. The temperature of the hot air is preferably 0 to 200 ° C. at a temperature T 1 of the thermometer 13.

In FIG. 1, reference numeral 11 denotes a dissolving tank. In the dissolving tank 11, the coating solution and the solvent are mixed and agitated to obtain a uniform dissolution solution 12 of the coating material as a coating solution. The concentration of the coating material in the mixed solution 12, that is, the coating solution concentration, can be appropriately adjusted according to the type of the coating material and the solvent, the temperature of the mixed solution 12, and the like. A concentration of 1 to 50% 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, quinylene, tetrachloroethylene, kerosene, etc. are preferred for ease of handling.

As described above, at least in the coating of the time-eluting coated granular fertilizer of the present invention.

It is preferable to adjust the moisture permeability of the coating by blending two types of coating materials. 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 combining at least two types of coating materials, there is a case where all types of coating materials to be used are mixed and stirred with a solvent in a dissolution tank to obtain one type of mixed solution. it can. When this one kind of mixed solution is used as a coating solution, a time-eluting coated granular fertilizer coated with one layer of a coating is obtained.

As a second example of a method of combining 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 each of the divided coating materials is separately set in a melting tank. In addition, 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 can be cited. When a mixed solution of two or more of these is used as a coating solution, a time-eluting type coated granular fertilizer coated with two or more layers is obtained. However, considering the complexity of the coating operation for forming such two or more layers of coating and the cost of capital investment for manufacturing equipment, etc., it is preferable that the coating be a single layer.

Next, the mixed solution 12 is sent by the pump 6 and sprayed from the spray nozzle 4 installed at the lower part of the jet tower 1 onto the core material 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 should have a double structure, by passing steam, etc. 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 keeping the temperature or heating.

When spraying the mixed solution 1 2 onto the core fertilizer particles 5, the temperature and time The operating conditions can be appropriately adjusted according to the types of the fertilizer material, the coating material, the solvent, and the like. However, it is generally preferable to perform the operation under the following conditions. That is, the mixed solution 12 is sprayed onto the core fertilizer particles 5 when the hot air temperature near the core fertilizer particles in the jet in the jet tower 1 reaches 50 to 200 ° C with a thermometer 14. The spraying is started from the point when it reached, and after spraying for 0.2 to 200 minutes, the spraying is stopped and the spray of the fertilizer particles is continued to dry for 0.2 to 200 minutes, and the coated granular fertilizer is dried. obtain. The obtained coated granular fertilizer is discharged from the outlet 7 provided at the bottom of the spout tower 1. When the core fertilizer particles 5 are coated with the two layers of coating, the first layer of coating liquid is sprayed and then the second layer of coating liquid is sprayed. Layer coating can be applied.

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, the cultivation method using the time-eluting coated granular fertilizer of the present invention will be described by taking a nursery box fertilization method and the like as examples.

Originally, during the cultivation period of crops and the like, fertilization and pesticide spraying are carried out at the appropriate time, and fertilization and pesticide spraying etc. are performed at the same time at the start of seedling raising or seeding and transplanting in this field. If this is done, there will be problems such as excessive concentration of crops due to excessive fertilization. To solve such problems, the development of coated fertilizers has been promoted, but with these coated fertilizers, elution of fertilizer components and the like during the initial elution suppression period is insufficient or unstable. is there. Therefore, even when these coated fertilizers are used, it is not possible to perform fertilization at once at the start of raising seedlings or at the time of sowing or transplanting to this field.

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

Time-eluting coated granular fertilizers are classified according to the function expressed 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. Regarding such a time-eluting type coated granular fertilizer, the time-eluting type coated granular fertilizer of the present invention 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 seedling container such as a pot, or at the same time as sowing or transplanting to this field.

The crops and the like 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, kiuri and kabochiya, It can be used for cultivation of wheat, corn, potatoes, beans, craft crops, flowers and the like. Example

Hereinafter, the present invention will be described more specifically with reference to 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 and maximum water absorption per 24 hours: 1.0 g of the coated granular fertilizer sample was immersed in 50 ml of water at 25 ° C, and after 24 hours, the sample was taken out of the water and the surface of the film was coated. After wiping off the water adhering to the surface with absorbent paper, etc., weigh it. This weight increase is the amount of water absorbed per 24 hours. Then, this sample was immersed again in 50 ml of fresh water at 25 ° C, and after a further 24 hours had elapsed, immediately after the lapse of 48 hours, The measurement is performed in the same manner as in the above sample, and the water absorption per 48 hours is determined. Such operations 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 reaches a maximum value. The water absorption amount that reaches this maximum value is the maximum water absorption amount). is there.

Circularity coefficient: Measured using a measuring device PIAS-IV manufactured by Pierce Co., Ltd.

Synthesis Examples 1 to 11

In preparing the core fertilizer particle samples, core materials such as fertilizer materials were granulated using the types and granulation methods shown in Table 1 to obtain samples A to C shown in Table 1. For sample B shown in Table 1, the granular raw material was supplied to a rotating disk type granulator and sized. The circularity coefficient 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 material fertilizer particle sample prepared as described above was coated with the coating under the conditions shown below and in Tables 2 and 3 using the coating apparatus shown in the schematic diagram of FIG. The coated granular fertilizer samples 1 to 11 shown in 3 were obtained.

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 (a) and the weight (b) of the coating is 100% by weight. l O OZ (a + b)].

Core fertilizer particle sample A B C

Fertilizer material Urea Potassium chloride Potassium sulfate Granulation method Jet granulation method Square cutting method ² Rolling granulation method

Average particle size 3.0

Roundness ^ (^)〉 99.9 99.2 99.4 Jet granulation with jet granulator

* ² granular raw materials are smoothed by a rotating disk-type granulator (Fuji Baudal, Malmeraizer QJ400)

* Rolling granulation with ³ bread granulator

* ⁴ Ratio of core fertilizer particles with a circularity coefficient of 0.7 or more n Test example No. 1 2 3 4 5 b I Coated granular fertilizer sample 1 2 3 4 5 6 7 Sample: fc BP is 卄 sop H / A

AA Hot air temperature T2 (C) 120 120 120 120 120 120 120 Coating material * ⁵ PE * '40 PE * ¹ 20 PE * ¹ 30 ΡΕ * '30 ΡΕ * ¹ 30 PE * '30 PE * ¹ 30

EEA * ² 20 PCL * ³ 10 Talc 55 Talc 55 Talc 65 Talc 65 Evening 65 Talc 65 Talc 60 Flour 5 Flour 5 Flour 5 Flour 5 Flour 5 Flour 5 Coverage * ⁶ (%) 12 12 12 12 12 12 12

Water absorption per 24 hours (%) 0.11 0.26 0.17 0.13 0.08 0.35-0.39 Maximum water absorption (%) 7.4 7.8 6.1 6.6 6.1 8.3 15.9 Whether or not listed in Fig. 2 Yes No Yes No No 辆 No No

D 1 * ⁷ (say) 66 30 36 51 76 21 42

D2 * ⁸ (say) 62 52 41 75 152 65 85

D 1 / D2 1.06 0.58 0.88 0.68 0.50 0.32 0.49

* 1 PE: low density polyethylene, melting point 110 ° C,

MFR = 7 (Test temperature 190 ° C, Test load 2.16kgf)

* 2 E E A: Ethylene Z copolymer with ethyl acrylate

Ethyl acrylate content 19%,

MFR = 5 (Test temperature 190 ° C, Test load 2.16kgf)

* 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 Figures for each coating material indicate parts by weight

* 6

Coverage: 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, that is, the formula

Value obtained by [bxl00 / (a + b)]

D 1: Initial dissolution inhibition period

* 8 D 2: Component elution period Table 3

1 Δ o o

Comparative S-test frequency 0.4 Coated granular fertilizer sample 8 9 10 11 Core fertilizer particle sample A A A A

Hot air temperature T2 (° C) 120 120 120 120

肤 T, J Τ-Τ 丄 u

PCL * ² 30 Rubber ³ 20 Rubber * ³ 40 Talc 30 Talc 65 Talc 50 Talc 55 Flour 5 Flour 5 Flour 5 Coverage ³ ^ () 12 12 12 12

Water absorption per 24 hours (%) 0.03 2. 7 2. 36.2

Q Q

O. Δ 0. 0 丄 d Δ ό Presence / absence in Figure 2 Yes No Yes Yes

D1 * ⁶ (say) 85 6 12 4

D2 ^J (say) 520 42 90 24

D 1 / D2 0. 16 0. 14 0. 18 0. 17 ΡΕ: 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 Z isoprene copolymer, Styrene: isoprene = 14: 86,

MFR = 9 (Test temperature 200 ° C, Test load 5kgf)

*Four

Numbers for each coating material indicate parts by weight

*Five

Coverage: 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, that is, the formula [bxl00 / (a + b) )]

* 6 D 1: Initial elution suppression period

* 7

D 2: Component elution period The jet tower 1 in FIG. 1 is a jet tower having a tower diameter of 250, a height of 200, an air outlet diameter of 50, and a cone angle of 50 degrees. The hot air sent from the blower 10 and heated by the heat exchanger 8 was circulated from the lower part to the upper part of the jet tower 1 in a circulating manner. At this time, the flow rate and the temperature T 1 of the hot air were measured by the orifice flow meter 9 and the thermometer 13, respectively, and the measured values were 4 m ³ Z and 1 30 ± 2 ° C., respectively.

Samples of core fertilizer particles shown in Tables 1 to 3 (in Fig. 1, core fertilizer particles 5 are shown) are placed in the jet tower 1 in which the hot air is circulating. 10 kg was injected from the core fertilizer particle inlet 2 installed on the surface and jetted.

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

The coating liquid was sent by a pump 6, and the coating liquid was sent at a flow rate of 0.1 kg Z from a spray nozzle 4 which is an 0.8 mm full-con type one-fluid nozzle installed at the lower part of the jet tower 1. The liquid is sprayed and sprayed onto the core fertilizer particle sample in the jet. The temperature of the coating solution was 80 ° C or higher. During the feeding of the coating solution, the piping and the like were kept warm or heated so that the temperature of the coating solution did not fall below 80 ° C. Here, the coating liquid temperature was measured in a pipe near the spray nozzle 4.

The coating liquid was sprayed onto the core material fertilizer particle sample in the jet stream in the jet tower 1 when the hot air temperature T 2 near the core material fertilizer particle sample reached the temperatures shown in Tables 2 and 3 using a thermometer 14. The spraying was started from the time when the temperature reached, and spraying was performed so that the coverage rate shown in Table 2 and Table 3 was reached.The spraying was stopped, and the jet of the fertilizer particles was dried continuously to obtain a coated granular fertilizer sample 1 to 11 I got

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

Test Examples 1 to 7

1.0 g of each of the coated granular fertilizer samples 1 to 7 obtained in Synthesis Examples 1 to 11 was immersed in 50 ml of water at 25 ° C, and allowed to stand at the same temperature. After a certain period from the start of immersion After that, 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. Then, the sample was immersed again in 50 ml of fresh water at 25 ° C. and allowed to stand at the same temperature. Further, after a lapse of a predetermined period, the amount of the fertilizer component eluted from the sample into water during the subsequent predetermined period was measured by the same operation as before. By repeating the above operation, the total value of the predetermined period, that is, the immersion period, is obtained in units of liters, the total value of the amount of the fertilizer component eluted from the sample into water during the immersion period is obtained, and the relationship between these total values is determined. This was represented by a graph, and an elution amount-dip curve was prepared. Figure 2 shows the immersion period-elution amount curves prepared for coated granular fertilizer samples 1 and 3 among these curves. 'From these immersion period / elution amount curves, the initial elution inhibition period (D 1) was determined by reading the immersion period until 10% of the fertilizer component of the coated granular fertilizer sample was eluted. Similarly, the component elution period (D 2) was determined from the immersion period-elution amount curve by reading the immersion period until the fertilizer component of the coated granular fertilizer sample eluted to 80%. D 1 ZD 2 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 D1ZD2.

Comparative test examples 1-4

Tests were performed in the same manner as in Test Examples 1 to 7, except that the coated granular fertilizer samples 8 to 11 obtained in Synthesis Examples 1 to 11 were used as coated granular fertilizer samples. The results shown were obtained.

From the test results shown in Table 2, for each of 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 It is 1.0 to 20% of its own weight. In addition, all of the coated granular fertilizer samples 1 to 7 have a sufficiently long initial elution inhibition period of 20 or more, and also have a ratio of the initial elution inhibition period to the component elution period, ie, D 1 ZD 2 of 0. 2 or more, indicating that it is suitable as a time-eluting coated granular fertilizer. For the coated granular fertilizer samples 1 to 7 and the coated granular fertilizer samples 8 to 11, based on the test results shown in Table 3, at least one of the water absorption per 24 hours or the maximum water absorption was within the above range. Therefore, it can be said that it is unsuitable as timed elution type coated granular fertilizer. Therefore, even if the initial dissolution inhibition period is as short as less than 20 days, or even if the initial dissolution inhibition period is sufficiently long as 20 or more, the D1 ZD2 becomes less than 0.2, making it unsuitable as a timed elution-type coated granular fertilizer. Become. 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 is reduced to a total of 35%, and the moisture permeability is low. The amount of polyethylene used was 65%. As a result, the maximum water absorption was 8.2%, which was within the range of 1.0 to 20%, but the water absorption per 24 hours was 0.03%, a low value of less than 0.05%. The component dissolution period of this coated granular fertilizer sample 8 was long, 520, and D 1 ZD 2 was less than 0.16 and less than 0.2, which proved to be unsuitable as a time-dissolved coated granular fertilizer.

In the case of the coated granular fertilizer sample 9, the amount of polyfunctional prolactone, 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 case of the coated granular fertilizer sample 6. Further, in the coated granular fertilizer sample 9, the amount of polyethylene, which is a material having low moisture permeability, was reduced compared to the case of the coated granular fertilizer sample 6. As a result, the maximum water absorption was 3.5%, which was within the range of 1.0 to 20%. However, the water absorption per 24 hours was 2.7%, which was 2.0%, which was unreasonably high. The initial dissolution inhibition period for this coated granular fertilizer sample 9 was as short as 6 days, and D1ZD2 was less than 0.14 and less than 0.2, indicating that it was unsuitable as a time-dissolved 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 a high strength and a high moisture permeability, is used as the material for coating the core fertilizer particles. The amount is the same as for the coated granular fertilizer sample 7. Many more. Further, in the coated granular fertilizer sample 9, the amount of talc used as the 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 higher at 12.3%, it was within the range of 1.0 to 20%, but the water absorption per 24 hours was 2.3%, which was unreasonably higher than 2.0%. Was. The initial dissolution inhibition period of this coated granular fertilizer sample 10 was as short as 12 days, and D1ZD2 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. Therefore, it is necessary to use a means such as increasing the water absorption per 24 hours as described above. 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 was still unreasonably high, exceeding 23% and 20%, and the water absorption per 24 hours was also unreasonably high, exceeding 6.2% and 2.0%. The initial dissolution inhibition period for this coated granular fertilizer sample 11 was short, 4 and the D1 to D2 were 0.17 and less than 0.2, indicating that it was unsuitable as a time-dissolved coated granular fertilizer.

Example 1

Based on the test results shown in Table 2, for the coated granular fertilizer samples 1 and 3, the water absorption per 24 hours was 0.11% and 0.17% of their own weight, respectively, and the maximum water absorption was also their own weight. It is 7.4% and 6.1%, which is suitable for timed elution type coated granular fertilizer. In addition, for these coated granular fertilizer samples 1 and 3, the leaching period-elution amount curve is as shown in FIG.

Therefore, the mixing ratio of these coated granular fertilizer samples 1 and 3 was 95: 5, The composition was changed every 5 units, 90:10, ·····, 5:95, and calculated from the respective composition ratios, and 19 kinds of leaching period / elution amount curves were drawn. As an example of these, Fig. 3 shows the leaching period-elution curve when the mixing ratio of 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 (minus nutrient absorption pattern) in Minamata 巿 bukuro, Kumamoto prefecture from the time of sowing to the time of harvesting in the field It was determined from the measured soil nutrient supply curve during the cultivation period (the amount of soil nutrient supplied by time) and the nutrient absorption curve of the cucumber (nutrient absorption by time). The basic data used to obtain these curves was the prototype data of the same crop conducted in the same area last year. The nutrient requirement curve of the cucumber obtained in the previous year obtained in this manner is shown in FIG. 3 together with the leaching period-elution amount curve when the mixing ratio of the coated granular fertilizer samples 1 and 3 is 60:40. The shapes and the like of these curves were compared. However, the nutrient demand curve is a curve that incorporates the temperature change during the cultivation period (range of about 18 to 32 ° C), and the temperature is 25 ° C during the measurement of the soaking period-elution amount curve. —The conditions are not exactly the same, but the average temperature during the cultivation period on the nutrient demand curve was approximately 25 ° C, so both conditions can be treated almost equally.

Comparing the two curves, it can be seen that both curves have very low initial elution and are very similar. As described above, from the test results shown in Table 2, for each of the coated granular fertilizer samples 1 and 3, the water absorption per 24 hours was 0.11% and 0.17% of their own weight. 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 time-eluting coated granular fertilizer.From the comparison in Fig. 3, the coated granular fertilizer samples 1 and 3 It was presumed that it would be more suitable to use coated granular fertilizer samples 1 and 3 as compounded fertilizer A with a mixing ratio of 60:40 than to use each of them individually as timed elution type coated granular fertilizer.

In a field in Minamata-Takabukuro, Kumamoto (location name), a cup using the compound fertilizer A A cultivation test of perilla was performed in the following procedure.

Previously prepared fertilizer at all against the nursery soil 1 0 0 ml that is not contained, the phosphorus component as seedlings fertilizer (P ₂ 0 ₅ component, hereinafter referred to as P.) 1 0 mg, potassium components ( K ₂ 0 component, hereinafter referred to Κ.) 1 O mg and nursery soil material 4 0 0 ml of a mixture of nitrogen component (N components present in the formulation fertilizers a, hereinafter abbreviated as N.) is 8.3 3 g (N per 15 a of the field is equivalent to 15 _kg ), mixed well with fertilizer A, filled into a 10 era diameter vinyl pot, and then seeded with cucumber seeds (cultivar: a One seed was sowed, and the seedling cultivation soil was covered on it, and seedlings were grown in vinyl pots from April 26 to May 6. After the completion of the seedling raising in the vinyl pot, the seedlings were transplanted to a field at a density of 180,000 trees, and cultivation in the field was started. After that, harvesting of the main stem began on July 6, and harvesting of side branches began on July 26, and harvesting was completed on September 20, and the cultivation was completed.

The seedlings are transplanted to the field, and fertilizer fertilizer containing P: 14% and K _: 14% as fertilizer components is divided into four times between the time the seedlings are planted in the field and the time they are harvested. did. The amount of fertilizer was adjusted so that P—K became 15 kg—15 kg per 10 a field in four fertilizations.

Comparative Example 1

N: 10 mg, .P: 10 mg, and K: 10 mg were mixed as a fertilizer for raising seedlings with 100 ml of the raising seedling culture medium containing no fertilizer prepared in advance. After filling 400 ml of the seedling cultivation material into a plastic pot with a diameter of 10 cm, sow one seed of cucumber seed (variety: Aso midori) and cover the seedling cultivation soil on it. From April 26 to May 6, they raised seedlings in plastic pots. After the completion of the seedling raising in the vinyl pot, the seedlings were transplanted to a field at a density of 1800 a 10a, and cultivation in the field was started. After that, the main stem began to be harvested from July 6, the side branches began to be harvested from July 26, and the harvest was completed on September 20 to finish the cultivation. Seedlings are transplanted to the field, and between the time the seedlings are planted in the field and the time they are harvested, an advanced fertilizer containing N: 14%, P: 14%, and K: 14% as fertilizer components is used. Fertilization was divided into four times. The amount of fertilizer was adjusted so that N—P—K was −15 kg−15 kg−15 kg per 10 a field in four fertilizations.

As described above, in the cultivation test of Comparative Example 1, N was fertilized, and in the cultivation test of Example 1 described above and Comparative Example 2 described later, the cultivation test of Limeflower was performed without N.

Comparative Example 2

From the test results shown in Table 3, for 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 1% of their own weight. 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 not suitable as a time-eluting type coated granular fertilizer. On the other hand, for these coated granular fertilizer samples 10 and 11, the leaching period-elution amount curves are as shown in FIG. In addition, in the case of the compound fertilizer B in which the mixing ratio of the coated granular fertilizer samples 10 and 11 was 80:20, the leaching period-elution amount curve was calculated using the mixing ratio of the coated granular fertilizer samples 1 and 3 described above. Is shown in Fig. 3 together with the leaching period-elution rate curve for the compound fertilizer A of 60:40 and the nutrient requirement curve of the previous year's cucumber, and the shapes of these curves are compared. did.

From the comparison of these curves, it can be seen that the immersion period-output curve for compound fertilizer A and the aforementioned nutrient demand curve of cucumber in the previous year are very similar, as described above. It can be seen that the immersion period-elution amount curve in the case of (1) was insufficiently suppressed in the initial elution, and was clearly different from the former two curves. As mentioned above, from the test results shown in Table 3, the water absorption per 24 hours was 2.3% and 6.2% of their own weight for the coated granular fertilizer samples 10 and 11, respectively. The amount of water is 12.3% and 23% of its own weight, and at least one of the water absorption or the maximum water absorption per 24 hours is out of the range of the present invention. Although it can be said that the coated granular fertilizer is unsuitable as a mold-covered granular fertilizer, the comparison in Fig. 3 shows that the coated granular fertilizer samples 10 and 11 were coated in the same manner as when they were used individually as time-eluting coated granular fertilizers. It was presumed that the use of the fertilizer B with the mixing ratio of the granular fertilizer samples 10 and 11 of 80:20 was also unsuitable. A cultivation test of cucumber using the compound fertilizer B was carried out in the same manner as in Example 1 except that compound fertilizer B was used in place of compound fertilizer A in a field in Minamata 巿 bag (place name), Kumamoto Prefecture. Was.

As a result of the cultivation test, no germination occurred in the cultivation test of Comparative Example 2 (germination rate: 0%). It is clear from this that the cause is excessive elution of fertilizer components in the early growth stage. As is evident from the elution curve of compound fertilizer B in Fig. 3, the initial elution of compound fertilizer B was not sufficiently suppressed, indicating that this excessive elution caused concentration disturbance to the seeds of Cucumber. . On the other hand, in the cultivation test of Example 1, the germination rate was 97%, and the germination rate in the cultivation test of Comparative Example 1 in which topdressing of N was performed was almost the same as the germination rate of 98%. there were. Also, the harvest index in the cultivation test of Example 1 was 102, which is comparable to the harvest index of 100 in the cultivation test of Comparative Example 1 in which topdressing of N was performed. It was.

From a work perspective, the following can be said. Since the work in the nursery box is performed in a narrow place called the nursery box, the work of Example 1 and the work of Comparative Example 1 are equivalent in terms of the workload. However, in the field work, since the work is performed in a wide area called the field, in Example 1, the amount of work can be greatly reduced because the topdressing of N is not required.

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 dissolution inhibition period of the coated granular fertilizer is sufficiently long, and the ratio of the initial dissolution inhibition period to the component elution period, that is, Dl ZD 2 can be 0.2 or more. in this way A good time-eluting type coated granular fertilizer can be obtained by controlling. In addition, the method for cultivating a crop using the time-eluting coated granular fertilizer of the present invention can significantly reduce labor of work and improve the use efficiency of fertilizer without reducing the germination rate and yield of the crop. It is to be.

Claims

The scope of the claims

1. By combining two or more types of thermoplastic resins used for the coating of coated granular fertilizer, or by using one type, the amount of water absorption per 24 hours to 0.05 to 2.0% of its own weight, the initial fertilizer component A method for controlling the dissolution control period of coated granular fertilizers in which the ratio D1ZD2 of the dissolution inhibition period (D1) to the component dissolution period (D2) is 0.2 or more.

2. Combine two or more of the thermoplastic resins used for the coating of the coated granular fertilizer, or use one of them to make the water absorption per 24 hours 0.05 to 2.0% of their own weight, and the coating of the coated granular fertilizer In addition, one or more substances insoluble in the solvent used for the coating liquid are added to make the maximum water absorption 1.0 to 20% of its own weight, so that the initial elution suppression period (D1) and the elution period of the fertilizer component (D1) A method for controlling the dissolution control period of coated granular fertilizer, wherein the ratio D1ZD2 to D2) is 0.2 or more.

3. A time-dissolved coated granular fertilizer having a dissolution control period controlled by the control method according to claim 1 or 2.

4. One or two or more thermoplastic resins and one or two or more substances insoluble in the solvent are mixed and dissolved in a solvent to obtain a coating liquid, and the coating liquid is coated on the core fertilizer particles. 4. The method for producing a time-eluting coated granular fertilizer according to claim 3.

5. A cultivation method using the time-eluting coated granular fertilizer according to claim 3.