JPH0229289B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pesticide-containing granular culture soil obtained by granulating microencapsulated pesticides together with soil minerals. Recently, with the spread of rice transplanters, rice seedlings have been grown in seedling boxes instead of the traditional seedlings, and the soil used for these seedling boxes has a particle size of 1.
Soil granular to about 5 mm (hereinafter referred to as "granular soil") is commercially available. In the production of this granular culture soil, an appropriate amount of fertilizer is included, but agricultural chemicals such as fungicides and insecticides are not included. There are various reasons for this, but the biggest reason is the occurrence of chemical damage caused by the coexistence of agricultural chemicals. However, if pesticides can be incorporated into granular soil so that the coexisting pesticides can act effectively at appropriate times without causing chemical damage, it would be extremely desirable from the perspective of saving labor in agricultural work. It is. For example, conventionally, when rice seedlings are grown in a nursery box and transplanted using a rice transplanter, or after transplantation, pesticides are applied, but if the granular soil for raising seedlings contains pesticides in advance, such work can be done. can be omitted. Also, recently, granular soil is used not only for raising rice seedlings, but also for raising rice seedlings.
It is desired that granular culture soil containing agricultural chemicals, which is used for growing various crops, can be used without fear of causing chemical damage. The present inventors have discovered that without causing drug damage, and in addition,
As a result of research into incorporating pesticides into granular culture soil in a form that acts effectively at desired times, it was discovered that granular culture soil made by microcapsulating pesticides and granulating them with soil minerals gives favorable results, and the present invention It came to this. The membrane material for microcapsules containing agricultural chemicals as a core material and present in granular culture soil is required to be chemically stable to the agricultural chemicals as the core material and capable of retaining the agricultural chemicals for a desired fixed period of time. When an amino resin such as a urea-formaldehyde resin, a melamine-formaldehyde resin, or a thiourea-formaldehyde resin is used as the membrane material, it is easy to adjust the release rate of the microencapsulated pesticide, and This material is particularly preferred since it is decomposed by microorganisms and has the advantage that no membrane material remains in the soil. In the present invention, the agricultural chemicals to be microencapsulated and contained in the granular culture soil include insecticides, fungicides, herbicides, antiviral agents, etc., and their properties may be either solid or liquid. A specific example of a pesticide suitable for microencapsulation and inclusion in granular soil is O,O-diethyl-S-2-(ethylthio)-ethylphosphorodithioate (dicistone) (2-isopropyl-
Organic phosphorus agents such as 4-methylpyrimidyl-6-)diethylthiophosphate (Diazinon), 3
-Propenazole drugs such as allyloxy-1,2-benziisothiazole-1,1-dioxide (Oryzemate), and carbamate drugs such as 2-isopropoxyphenyl-N-methylcarbamate (Suncide). can. Microencapsulation of these pesticides can be performed by known methods. When two or more types of agricultural chemicals are to be contained in the granular culture soil, they are each microencapsulated separately, or when the two or more types of agricultural chemicals are chemically stable to each other, they are microencapsulated together. It's okay. Microencapsulation can be performed, for example, by the following method. The pesticide to be microencapsulated is emulsified and dispersed in an aqueous mixture consisting of a resin prepolymer made of formaldehyde and at least one selected from urea, melamine, and thiourea, a water-soluble cationic urea resin, and an anionic surfactant. The resin is polycondensed by maintaining the pH of the solution in the acidic range. The pesticide-containing granular soil of the present invention is produced by adding and mixing the above-mentioned microencapsulated pesticide in a desired amount to dry and pulverized soil minerals, and then by a known granulation method.
It can be obtained by molding into particles of about 5 mm. The amount of pesticide microcapsules to be mixed into the granular soil of the present invention is appropriately determined depending on the proportion of the pesticide in the microcapsules, the type of pesticide, the type of crop grown in the granular soil, etc., but in many cases,
The amount ranges from 1 to 10 g per 1 kg of soil minerals. When the granular culture soil of the present invention is used, microencapsulated agricultural chemicals are released in a sustained manner and exhibit their effectiveness over a long period of time. The period during which the pesticide is effective can be adjusted as appropriate by changing the type and thickness of the membrane material of the microcapsule. Next, we will give an example of the production of microencapsulated agricultural chemicals. The microencapsulated pesticide obtained in this production example was added to the granular culture soil A in the example. Microencapsulated pesticides added to other granular culture soils B to E were also produced in substantially the same manner. Example of manufacturing microcapsules: Mix 40 g of 37% formaldehyde aqueous solution and 12 g of urea, add triethanolamine to the mixture, adjust the pH to 8.5, and react at 70°C for 1 hour with stirring to form a urea-formaldehyde resin prepolymer. An aqueous solution was obtained. In this, Yulamin P-
Add 10 g of 1500 (38% aqueous solution of cationic urea resin manufactured by Mitsui Toatsu Co., Ltd.) and 1.5 g of a 10% aqueous solution of sodium n-dodecylbenzenesulfonate, and then add water to bring the total weight to 150 g. Add 10% citric acid to this mixture. The pH was adjusted to 5.2 by adding aqueous solution. Add 79 g of oryzemate to this liquid and emulsify it with a homogenizer so that the diameter of the oryzemate droplets is 2 to 8 μm. Next, while gently stirring this emulsion, adjust the pH to 3.5 with a 10% citric acid aqueous solution. The temperature was kept at 50℃ and the reaction was allowed to proceed for 1 hour, and the reaction product was then poured with water while keeping the temperature at 50℃ and stirring continued.
The reaction continued while adding 300 g dropwise over 1 hour. When the dropwise addition of water was completed, a 10% citric acid aqueous solution was added to adjust the pH to 2.6, and the reaction was allowed to proceed for 40 minutes. After that, the mixture was allowed to cool and was kept at room temperature for another 10 hours. Stirring was continued to obtain a microcapsule slurry of oryzemate.
The capsules were then separated (with paper), washed with water, and air-dried to yield a free-flowing powder. Example 1 Aqueous rock-based soil collected near Nishiki-cho, Iwaki City, Fukushima Prefecture was air-dried, then crushed and sieved to particles with a particle size of 100 μm or less to obtain a raw soil mineral. To this soil mineral, a predetermined amount of the microencapsulated agricultural chemicals shown in Table 1 is added and mixed uniformly, polyvinyl alcohol (equivalent to 0.1% by weight based on the soil mineral) and water are added and mixed, and the mixture is processed using an extrusion granulator. The pellets were granulated and dried to a diameter of 1 to 5 mm to obtain granular soil containing the agricultural chemical of the present invention.

[Table] Example 2 (Underwater leaching test) 800 g of each of the granular soils A to C produced in Example 1 were packed separately into rice seedling boxes with a depth of 3 cm, and 1.
Sprayed with 500ml of water once a day and placed indoors. Every 10 days, take 80g of granular soil from each box and add 50ml of water to it.
was added and allowed to stand for 24 hours, and the concentration of oryzemate in the filtrate was measured using a spectrophotometer. The results are shown in Table 2.

[Table] For comparison, measurements were also made on granular culture soil mixed with commercially available 8% granules instead of microencapsulated oryzemate. Example 3 Using the granular soils D and E obtained in Example 1, paddy rice was raised in a box using a conventional method, and the presence or absence of phytotoxicity during box raising was determined.
Seedlings were transplanted for 21 days, and the insecticidal effect after transplantation was observed. For boxed seedling raising, the amount of granular culture soil used per box was 2.5 kg (5 g of diazinon), and for the insecticidal test, paddy soil was placed in a 4-inch pot and one rice seedling (adhered soil amount: 1.67 g) was transplanted into it. Thirty leafhoppers were released every 5 days, and the rate of supination was examined 48 hours later. For comparison, seedlings were raised in granular culture soil mixed with commercially available 3% granules of DAIDINON instead of microencapsulated DIAZINON (Comparative Example 1) and bed soil without diazinon, and 3% granules of commercially available DAIDINON were added at the time of transplantation ( Comparative Example 2) was also observed. The results are shown in Table 3.

[Table] * Unable to obtain seedlings for rice transplantation due to chemical damage

Claims (1)

[Claims] 1. A microencapsulated pesticide whose membrane material is obtained by polycondensing a resin prepolymer made of formaldehyde and at least one selected from urea, melamine, and thiourea in the presence of a cationic urea resin and an anionic surfactant together with soil minerals. Pesticide-containing granular soil made by granulation.