JPH0959622A - Biocontrol soil treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively treating soil by using a composition containing an azide compound, whereby the fumigating effect can be heightened, and the concentration of the azide compound and hydrogen azide remaining in the treated soil can be quickly lowered. SOLUTION: When a composition containing an azide compound which forms hydrogen azide when decomposed and used in an amount to control life harmful to useful plants is sprayed over soil, a soil conditioner, desirably peat moss, is sprayed over the soil before or during spraying this composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for promptly removing an azide compound when a composition containing an azide compound capable of generating hydrogen azide upon decomposition is sprayed on soil to control a harmful organism to crops. The present invention relates to a soil improvement method for enhancing a fumigation effect by hydrolysis and further suppressing or preventing phytotoxicity caused by hydrogen azide remaining after a fumigation treatment and an undecomposed azide compound.

[0002]

2. Description of the Related Art Conventionally, intensive cultivation has been performed in institutional horticulture and vegetable cultivation, and obstacles due to continuous cultivation due to such cultivation are often seen. The main reason why good crops cannot be obtained by continuous cropping is due to pests in the soil, so a comprehensive soil treatment agent that can control these and is also effective in controlling weeds that leads to labor saving. Is required.

The known DD agent (active ingredient: 1,3-dichloropropene) is effective against nematodes but not fungi and weeds, and CP agent (active ingredient: trichloronitromethane) is not effective against nematodes. Effective against fungi, but weak against nematodes and weeds, nemamol granules (active ingredient: 1,3-dichloroisopropyl ether) are only nematodes effective, and basamide microgranules (active ingredient: 3) , 5-dimethyltetrahydro-
2H-1,3,5-thiadiazin-2-thione) is a nematode,
Although it is effective against fungi, it is weak against weeds and has drawbacks such as variations in effects and phytotoxicity due to soil moisture.

Further, an azide salt such as an alkali metal azide salt is hydrolyzed in soil to generate hydrogen azide, which exhibits biological activity and is effective in controlling pests and weeds in the soil. Known, (Can.J.Microbiol ； vol
21.P565-570, 1975), soil fumigation with azide compounds is an effective means for controlling soil pests and weeds. However, when a composition containing an azide compound is used as a fumigant for soil, the neutral and alkaline soils are acidic compared to acidic soils, and in the alkaline soil, it takes time to generate hydrogen azide due to hydrolysis of the azide compound, resulting in a fumigation period. It becomes longer and the fumigation effect becomes weaker, and after the fumigation treatment, hydrogen azide and undecomposed azide compounds remain, and after leaving this for a period of 3 to 4 weeks to sufficiently disperse it, useful plants Had to be sown and planted. However, in the current agricultural management, especially in cultivation using facilities, it is not desirable to leave it unused for a long period of time because of delay in cost and planting time, and fumigation treatment is effectively performed in a short period, Furthermore, it is necessary to remove hydrogen azide and undecomposed azide compounds remaining in a short period of time.

[0005]

The object of the present invention is to achieve a purpose of fumigation treatment in a short period of time when a composition containing an azide compound is rapidly hydrolyzed in soil to generate hydrogen azide. Provides a method for soil improvement for further removing hydrogen azide and undecomposed azide compounds remaining in soil in a short period of time after fumigation treatment to prevent occurrence of phytotoxicity of useful plants sown or planted. Especially. As a result of extensive studies conducted by the present inventor to achieve this object, they have found that a fumigant treatment effect can be enhanced and the phytotoxicity can be prevented by spraying a soil conditioner, preferably peat moss, on the soil, Reached

[0006]

That is, according to the present invention, a composition containing an azide compound capable of generating hydrogen azide by decomposition is applied to soil in an amount effective for controlling harmful organisms to useful plants. In this case, a biocontrol soil treatment method is provided, which comprises applying a soil improver, preferably peat moss, to the soil before or at the same time as applying the composition to the soil.

The azide compound capable of generating hydrogen azide by decomposition used in the present invention may be any compound which is decomposed by the action of water, for example, an azide salt, particularly an alkali metal salt or an alkaline earth metal. Metal salts are preferable, and specifically, sodium azide, potassium azide, calcium azide, barium azide and the like are used, and sodium azide is particularly preferable.

When spraying such an azide compound,
As its form, a solid powder, a water-decomposable composition substantially consisting of an azide compound capable of generating hydrogen azide by decomposition and a water-soluble binder and an aqueous solution of an azide compound dissolved in water are preferably used. In particular, the former water-decomposable composition is more preferably used because it is easy to handle and excellent in workability.

The solid powder, which is one component of the above-mentioned water-decomposable composition, is used for the purpose of stably diluting the azide compound and easily forming it into a fixed shape. The solid powder may be, for example, a mineral substance, a vegetable substance, a synthetic product, a semi-synthetic product or a natural product, and the mineral substance may be clay, calcium carbonate, vermiculite, perlite, talc,
Acid clay, kaolin, zeolite and the like can be mentioned, and as the plant material, there can be mentioned cellulose hydrolyzate, rice husk, pulp and the like, and powders of ethylene-vinyl acetate copolymer and the like may be used.

The water-soluble binder is used for the purpose of effectively acting the azide compound as a soil treatment agent together with the solid powder and shaping the composition into a good form, and the binder is water-soluble, and It is preferable that the polymer be soluble in an organic solvent. This water-soluble binder has a content of 200 to 200 liters per liter of water at 20 ° C.
A solvent that dissolves in the range of 3,000 g, preferably in the range of 300 to 1,000 g is suitable. Those having a solubility lower than 200 g / liter require a large amount of solvent for preparing the composition. On the other hand, if the solubility is higher than 3,000 g / liter, it is difficult to maintain an appropriate viscosity and there is a problem in molding.

The water-soluble binder has a function of molding a composition comprising a solid powder and an azide compound into an appropriate form, and after being sprayed in soil, the molded product is disintegrated by the action of water to azide. It has the function of promoting the generation of hydrogen. Examples of the water-soluble binder include starch, dextrin, sodium alginate, gum arabic, gelatin, lignin, hydroxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose,
Hydroxypropyl cellulose, polyvinyl alcohol, polyvinyl methyl ether, polyacrylamide,
Partially saponified polyvinyl acetate, polyethylene glycol,
Examples thereof include polyvinylpyrrolidone and vinylpyrrolidone-vinyl acetate copolymer.

Of these, polyethylene glycol is preferred in terms of moldability and controllability. In particular, polyethylene glycol has a solubility in water of 200-
3,000 g / liter, more preferably 300 to 1.0
It is preferably 00 g / liter. Generally, those having a weight average molecular weight of 1,000 to 15,000 are preferable.

In the present invention, the above-mentioned water-decomposable composition preferably used is stable and safe in the atmosphere itself. However, when this composition is sprayed into the soil and mixed with the soil, the molded product collapses due to the moisture in the soil, and the azide compound comes into contact with water and decomposes to generate hydrogen azide.
At this time, in the acid soil, the decomposition of the azide compound is further promoted by the acidity. Therefore, the water-decomposable composition of the present invention is effective for acidic soil, and for neutral or alkaline soil, it is effective to acidize the composition itself or acidify the soil. is there. Regarding the acid treatment of the composition itself, for example, a hydrolyzing agent for an azide compound such as an organic acid is added to the composition, or the solid powder as a component of the composition is treated with an acid such as acid clay. Means for making a solid powder can be mentioned.

The water-decomposable composition substantially comprising the solid powder, the azide compound capable of generating hydrogen azide by decomposition, and the water-soluble binder is preferably used in the present invention. It is particularly preferred that they be used. Further, the preferable ratio (weight) of each component of the water-decomposable composition particles, when the composition is 100, is a solid powder of 30 to 98, more preferably 50 to 90, and an azide compound of 1 to 40, more preferably. 5 to 30, and a water-soluble binder of 0.1 to 30, more preferably 2 to 20. The composition particles are preferably used as a soil treatment agent for controlling soil diseases.

When the solid powder is less than 30% by weight,
Since the amount of the azide compound is relatively large, it takes time for the azide compound to hydrolyze, which is not preferable.
When it is more than 8% by weight, the proportion of azide compound becomes relatively small and it becomes impossible to obtain a high concentration of hydrogen azide necessary for showing the effect of controlling soil diseases. 1 azide compound
When it is less than wt%, the effect of controlling soil diseases is inferior, and when it is more than 40 wt%, the hydrolysis time of the azide compound becomes long, which is not preferable. When the amount of the water-soluble binder is less than 0.1% by weight, or when it exceeds 30% by weight, a good molded product required for uniform dispersion cannot be obtained, and it becomes difficult for the azide compound to act effectively in the soil. .

The soil treatment agent for controlling soil diseases is
It is preferably in the form of granules (granule) formed into a form having an average particle size of 100 μm to 2,000 μm. The average particle size of the particles as the soil treating agent is 300 μm to 1.5
The range of 00 μm is more preferable. This average particle size is 100
If it is less than μm, the granules are likely to be scattered during spraying, the applied amount to the target site varies, and the risk of exposure to the worker increases. On the other hand, when it is more than 2,000 μm, the spraying effect is not uniform and there is a portion where the control effect is insufficient locally, which is not preferable. The soil treatment agent is preferably a granular material having an average particle diameter of 100 μm to 2,000 μm, but it is desirable that the particle diameter distribution is not so wide, and sharpness is more effective.

This granule has a total weight of particles having a particle size of 300 μm or less and particles having a particle size of 1,500 μm or more,
20% or less, preferably 1%, based on the total weight of all particles
It is preferably 5% or less. Thus, the particle size is 300
If the total amount of particles smaller than μm and particles having a particle size larger than 1,500 μm exceeds 20%, the spraying effect of the particles becomes uneven, and there is a portion where the control effect is insufficient locally, It is not desirable because the control activity is difficult to control.

The average particle size of the solid powder constituting the granules is preferably in the range of 10 μm to 100 μm, and 40
The range of μm to 80 μm is more preferable. If the average particle size of the solid powder is out of the above range, it is difficult to achieve the object of the present invention.

The method for producing such granules is not particularly limited, but for example, a mixture of solid powder and an azide compound and a mixture of a binder dissolved in an organic solvent are kneaded in a kneader to be extrusion-molded or compression-molded. Granulation method, or a mixture of a solid powder and an azide compound and a binder dissolved in water are kneaded in a kneader and extruded or compression-molded to granulate, which is then dried to remove moisture. A method of removing is used. The organic solvent used in this production method is preferably one that is inactive to the azide compound and that dissolves the binder, for example, alcohols such as ethanol and butanol; ketones such as acetone and methyl ethyl ketone;
Aromatic hydrocarbons such as toluene and xylene are included.

Such a granule is a granular substance in which a solid azide compound and a solid powder are bound by a binder, and the azide compound is not decomposed in the air atmosphere and has good storage stability, and in the soil, in the soil. The azide compound is hydrolyzed by the water content of the product and exhibits an excellent effect of controlling soil diseases.

On the other hand, as a composition containing an azide compound capable of generating hydrogen azide by decomposition, an aqueous solution of the azide compound can also be preferably used. When an aqueous solution of an azide compound is used, the concentration of the azide compound is 5-4.
A range of 0% by weight is preferred. If the amount is less than 5% by weight, the amount of water becomes unnecessarily large, and the azide compound becomes difficult to diffuse.
Exceeding the weight percentage results in dispersion during application, and the control effect is insufficient, which is not preferable.

The aqueous solution of the azide compound is stable under neutral and alkaline conditions, but when it is made acidic, the azide compound is easily decomposed. That is, the aqueous solution of the azide compound is suitably neutral or alkaline, and the pH is suitably in the range of 7 to 12, preferably 7 to 11. When this aqueous solution of an azide compound is sprayed into soil, the acid compound immediately decomposes the acid compound in the acidic soil. On the other hand, for neutral or alkaline soil, it is effective to acidify the soil or to spray a compound that accelerates hydrolysis of the azide compound.

The spraying treatment with the azide compound described above
A soil treatment method in which a composition containing an azide compound is applied in an amount of at least 1 kg, preferably at least 3 kg per 10a as the amount of the azide compound is preferably used. If the amount of the azide compound is less than 1 kg / 10a, it is not preferable because it is less effective in treating soil diseases.

In these spraying treatments, the content of the azide compound in the composition is preferably 1 to 4% by weight,
If it is less than 1% by weight, the dosage per 10a is unnecessarily increased, and if it is more than 40% by weight, the dosage as a soil treatment agent is decreased and variations are likely to occur, which is not preferable. As a method of applying such a soil treating agent, a method of directly and evenly sowing the soil, such as manual sowing or a granulator, may be used.

In the spraying treatment, the soil sprayed with the composition containing the azide compound may be left as it is, but it is advantageous to cover it with a sheet.
The coating period is preferably in the range of 3 to 10 days after spraying. By coating, the hydrogen azide generated by the decomposition of the azide compound does not volatilize into the air, and the sprayed amount directly acts on soil pests and is preferably used.

In the present invention, a soil improver, preferably peat moss, is sprayed on the soil before or at the same time as spraying the composition containing the azide compound on the soil. By spraying such a soil improver, the azide compound is quickly hydrolyzed in the soil to generate hydrogen azide, the purpose of fumigation treatment is efficiently achieved in a short period of time, and after fumigation treatment, it remains in the soil. Hydrogen azide and undecomposed azide compounds are removed in a short period of time to prevent phytotoxicity of useful plants sown or planted.

In the present invention, peat moss, which is preferably used as a soil improving agent, is an animal and plant soil improving material, and is obtained by thoroughly washing water peat (grass charcoal) with water, drying and pulverizing it, and it is strongly acidic. Therefore, some of them are neutralized by adding slaked lime. It is preferable to mix the ones whose acidity is not neutralized with lime at the time of use and to neutralize them before use. Pete moss is usually used as a gardening material, mainly for improving the physical properties of potting soil. Wheat,
It may be used as a substitute for beet, beans and the like, but it is rarely used in upland fields where vegetables suitable for the method of the present invention are cultivated.

The amount of peat moss applied to soil is 10a.
A suitable amount is 100 kg or more, and there is no particular upper limit.
However, in neutral to weakly alkaline soil, an application rate of 1 to 3 t is appropriate. Further, the application time may be before application of the composition containing the azide compound or at the same time as application,
At any time, the effect of the soil treatment agent containing an azide compound as a pesticide is not impaired. When peat moss is admixed with the soil before spraying the composition containing the azide compound, it may be 1 to 14 days before, preferably 3 to 7 days before. When peat moss is applied at the same time as the composition containing an azide compound, it is preferable to spray peat moss and the composition onto the soil surface and then mix the soil with a tractor or a hoe.

It is considered that the effect of applying peat moss to soil is largely related to the fact that peat moss itself is an acidic substance. The azide compound has a property of rapidly hydrolyzing in acidic soil, and mixing peat moss, which is an acidic substance, in the soil makes the pH of the soil acidic, which accelerates the hydrolysis of the azide compound. Therefore, when the soil pH is neutral to weakly alkaline, it is preferable to correct the soil pH by applying peat moss 1 to 14 days before spraying the composition containing the azide compound. When the soil pH is neutral to weakly acidic,
By applying peat moss at the same time as spraying the composition, the azide compound can be rapidly decomposed to generate hydrogen azide, and fumigation treatment can be efficiently performed in a short period of time.

The composition containing the azide compound can be used as azide compound in an amount of 1 to 50 kg / 10 in normal use.
Used as a soil treatment agent in the range of a, but especially 20k
When using g / 10a or more, it usually requires a period of 3 weeks or more from the start of fumigation to the sowing or planting of useful plants. However, as in the present invention, by applying peat moss before or simultaneously with the soil treatment, the azide compound is rapidly decomposed, and the residual azide concentration in the soil can be reduced in a short period of time.

[0031]

【Example】

Example 1 850 parts of talc (manufactured by Nippon Talc Co., Ltd.) was added to 100 parts of sodium azide (manufactured by Toyo Kasei Co., Ltd.) and mixed to form a kneader (DHJ-10 type manufactured by Fuji Paudal Co., Ltd.). It was kneaded with a kneader while adding a solution prepared by dissolving 50 parts of polyethylene glycol (weight average molecular weight 7,500, manufactured by Wako Pure Chemical Industries, Ltd.) in 200 parts of water. Next, the extruder was extruded with an extrusion granulator (DG-L1 type, manufactured by Fuji Paudal Co., Ltd.) equipped with a screen having a hole diameter of 0.8 mm.
(J-230 type) to obtain granules having an average particle size of 1,000 μm. The granules were dried with a drier (Fluidizer 2F type manufactured by Fuji Paudal Co., Ltd.) to obtain 1,000 g of granules containing 10% by weight of sodium azide. 1 of this granule
1 / 5000a Wagner pot soil (pH 7.2)
Peat moss (Matsuei Sangyo Co., Ltd.)
(Manufactured) was mixed with soil at a rate of 500 kg to 3 t per 10 a. Then, a fumigation treatment was carried out for 7 days, and the amount of reduction of the azide compound and hydrogen azide after degassing was measured. High-performance liquid chromatography was used for the measurement, and the azide ion (N ₃ ⁻ ) concentration in the soil was examined. In addition, 50 mulberry seeds with Fusarium attached to soil were pre-filled in the soil, taken out after fumigation treatment, and then judged to be alive or dead.
The sterilization rate was calculated by. The results are shown in Table 1.

[0032]

[Equation 1]

[0033]

[Table 1]

Example 2 The granules obtained in Example 1 were sprayed onto 1 / 5000a Wagner pot soil (pH 6.0) at a ratio of 5 kg of sodium azide per 10a, and 100 kg of peat moss per 10a. The soil was mixed by spraying 1 t.
After that, the fumigation is performed by degassing by covering with fumigation for 7 days.
After 14 days, the soil was sampled and the residual azide concentration was measured. In addition, 50 mulberry seeds to which Fusarium fungus adhered were embedded in the soil in advance, taken out after fumigation treatment, and life or death was determined, and the sterilization rate was calculated by the calculation formula 1 of Example 1. The results are shown in Table 2.

[0035]

[Table 2]

[0036]

EFFECTS OF THE INVENTION According to the method of the present invention, a method for controlling pests in soil using a composition containing an azide compound capable of generating hydrogen azide is used in combination with a soil improver, especially peat moss. By doing so, the pest can be effectively exterminated in a short period of time, and after the extermination, the azide compound and hydrogen azide can be removed in a short period of time, and the seeding or planting time can be shortened.

Claims (4)

[Claims] 1. When a composition containing an azide compound capable of generating hydrogen azide by decomposition is applied to soil in an amount effective for controlling harmful organisms to useful plants, the composition is applied to the soil. A biocontrol soil treatment method, which comprises applying a soil conditioner to soil before or simultaneously with application. 2. The soil treatment method according to claim 1, wherein the soil improver is peat moss. 3. The soil treatment method according to claim 1, wherein the azide compound is an alkali metal azide salt or an alkaline earth metal azide salt. 4. The soil treatment method according to claim 1, wherein at least 100 kg or more of peat moss is sprayed per 10 a before or simultaneously with spraying the composition containing the azide compound to the soil.