JP2006298861A - Weed suppressing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weed suppressing agent suppressing growth of weeds over a long period without adversely affecting set plants or the natural environment and without requiring cost such as personnel expenses. <P>SOLUTION: The weed suppressing agent checks thick growth of weeds by sprinkling before the thick growth of the weeds. The weed suppressing agent comprises calcium cyanamide and a degradation inhibitor inhibiting the degradation of cyanamide produced as an intermediate product in a process of degradation reaction in which the calcium cyanamide is degraded by contact with water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a herbicide for preventing the growth of weeds in advance.

  Weeds grow in the summer in various business sites and fallow fields. Since weeds consume nutrients in the soil, they not only affect the growth of planted plants or cultivated plants, but also cause adverse effects such as damage to the landscape, so weeds need to be treated as early as possible. As a conventional weed treatment method, in addition to the method of eliminating the weed by spraying the herbicide after the weeds overgrowth, if you do not want to apply drugs such as herbicide or are not applicable, as an alternative, Mowing was done by human power. In such a conventional weed treatment method, when a chemical such as a herbicide is sprayed, it cannot be ignored as having no effect on the planted plant or the natural environment due to the chemical. Since the pharmacological action of the herbicide is not maintained for a long time, there is an inconvenience that a medicine such as a herbicide must be frequently sprayed. Moreover, in the conventional weed processing method, when a chemical | medical agent is not applied, there also exists a problem that costs, such as a huge labor cost, must be considered.

Thus, considering the conventional weed treatment method, it is considered that it is a desirable choice to take measures against weeds before the weeds grow.
"The identification of cyanamide as a plant growth inhibitor in hairy vetch leaves" by Yoshiharu Fujii et al., 41st Annual Meeting of the Japan Weed Society (2002)

  The purpose of the present invention is to spread before weeds, so that planting plants and the natural environment are not adversely affected, and there is no significant labor cost, etc. It is in providing the herbicide which suppresses growth.

  The invention according to claim 1 of the present invention is a herbicide that is sprayed before weeds grow to prevent weeds from growing, and is a decomposition reaction in which lime nitrogen is decomposed by contact with water. It contains a decomposition inhibitor that suppresses the decomposition of cyanamide produced as an intermediate product in the process.

  According to the present invention, a herbicide that is sprayed before weeds are grown to prevent weeds from growing, and is an intermediate product in the decomposition reaction process in which lime nitrogen is decomposed by contact with water. The decomposition inhibitor suppresses the decomposition rate of cyanamide, which exhibits an excellent herbicidal effect, and suppresses the growth of weeds over a long period of time. This has the effect of suppressing the growth of weeds. In addition, according to the present invention, although the degradation rate of cyanamide is delayed by the degradation inhibitor, cyanamide is finally degraded to ammonia as a fertilizer via urea, so that it is well known for planted plants or cultivated plants. It can be used safely as a fertilizer, has no adverse effect on planted plants or the natural environment, and does not require a large labor cost.

Embodiment 1 FIG.
A herbicide according to an embodiment of the present invention is sprayed before weeds overgrowth to prevent weed overgrowth, and lime nitrogen and decomposition in which the lime nitrogen is decomposed upon contact with water. It contains a decomposition inhibitor that suppresses the decomposition of cyanamide produced as an intermediate product during the reaction process.

  Lime nitrogen is produced by fixing air nitrogen, and is the first fertilizer for human beings that was originally invented at the end of the 19th century. After the development of ammonium sulfate produced by the ammonia synthesis method by Harbor Bosch and urea produced by the urea synthesis method by Mitsui Toatsu Chemicals Co., Ltd. It is not used so much as nitrogen fertilizer because it does not reach the point.

Lime nitrogen is a mixture of unreacted carbide and carbon containing about 20% of calcium cyanamide (CaCN ₂ ). Calcium cyanamide (CaCN ₂ ), which is an active ingredient of this lime nitrogen, acts on the carbide (CaC ₂ ) generated from the reaction of quick lime (CaO) and carbon (C) with air nitrogen (N ₂ ) at 1500 ° C. (See Chemical Formula 1).
_{CaC 2 + N 2 = CaCN 2} + C ··· Formula 1

When such lime nitrogen is sprayed into the soil, for example, calcium cyanamide (CaCN ₂ ) reacts with moisture in the soil and decomposes to produce cyanamide (H ₂ CN ₂ ) as an intermediate product. (See Chemical Formula 2).
CaCN ₂ + 2H ₂ O = H ₂ CN ₂ + Ca (OH) ₂ Chemical formula 2

The produced cyanamide (H ₂ CN ₂ ) further reacts with moisture to produce urea ((NH ₂ ) ₂ CO) (see Chemical Formula 3).
H ₂ CN ₂ + H ₂ O = (NH ₂ ) ₂ CO: Chemical formula 3

Urea ((NH ₂ ) ₂ CO) further reacts with moisture and decomposes to produce ammonia (NH ₃ ) (see Chemical Formula 4).
(NH ₂ ) ₂ CO + H ₂ O = 2NH ₃ + CO _2.

  For this reason, when lime nitrogen in a normal use state is sprayed in the soil as a fertilizer, then in a series of reaction processes from Chemical Formula 2 to Chemical Formula 4 in 1 to 2 weeks, as an intermediate product Through this cyanamide, it is decomposed into urea and / or ammonia, which are harmless fertilizer components, and exhibits an excellent fertilizer effect. When used in the series of reaction processes, the cyanamide is decomposed early in the soil and does not remain in the soil.

  By the way, when this inventor examined the decomposition reaction of the lime nitrogen from which lime nitrogen exerts the effect as a fertilizer, cyanamide which is an intermediate product of the decomposition reaction is excellent in a trace amount (10 ppm to 100 ppm). Attention was paid to the point (Non-patent Document 1) that shows the herbicidal effect. By the way, according to Non-Patent Document 1, cyanamide is an allelopathic activity of hairy vetch (scientific name: Vicia angustifolia), one of the legumes, which inhibits the growth of other plants by secreting special chemical substances. ) Is a plant-derived herbicidal substance identified by Fujii et al., So there is no safety problem in use. Based on such findings, the present inventor decomposes cyanamide, which exhibits a herbicidal effect, into urea and / or ammonia as a fertilizer component even when lime nitrogen is sprayed into the soil under normal use conditions. As a result, cyanamide no longer remains in the soil, and we cannot expect the herbicidal effect of cyanamide at all.However, by stabilizing the cyanamide by slowing the degradation rate of cyanamide, we ensure that the herbicidal effect is maintained for a long time. In order to create a new herbicide that prevents the growth of weeds by maintaining it, we conducted intensive studies.

  The degradation reaction of cyanamide is a hydrolysis reaction as shown in Chemical Formula 3 above, and the present inventor considered as follows in order to suppress this reaction and stabilize cyanamide. That is, in general, the hydrolysis reaction is accelerated under an extreme pH range such as strong acidity or strong alkalinity. In the hydrolysis reaction of lime nitrogen, the lime nitrogen comes into contact with water and exhibits strong alkalinity due to the contained calcium content. Under such strong alkalinity, the hydrolysis reaction is promoted regardless of the presence or absence of catalyst substances and microorganisms. Conversely, it was considered that when this alkalinity is neutralized to the neutral range, the hydrolysis reaction is not promoted and cyanamide may be stabilized. Therefore, by spraying a composition containing lime nitrogen with an acidic substance as a decomposition inhibitor into the soil, it is possible to neutralize the alkalinity that appears when the calcium content in lime nitrogen comes into contact with moisture with the above acidic substance. I thought.

  The decomposition inhibitor in the herbicide in this Embodiment 1 is an acidic substance that neutralizes the alkalinity exhibited in the lime nitrogen decomposition reaction process. Examples of the acidic substance include one or more substances selected from the group consisting of organic acids such as citric acid and succinic acid, microencapsulated hydrochloric acid and nitric acid such as nitric acid. Here, when an inorganic acid such as hydrochloric acid or nitric acid is used as a decomposition inhibitor, the reason for adopting the use form in which the above-mentioned inorganic acid is encapsulated in the microcapsule is easy to handle because the inorganic acid is strongly acidic. In addition, when the above-mentioned inorganic acid is directly applied to lime nitrogen, it is to avoid the influence of the soil due to heat generated by the neutralization reaction. It is also for giving to. As a method for microencapsulation of inorganic acid, for example, petroleum paraffin dissolved by heating is added to the inorganic acid to form a slurry, and the solidified product obtained by solidifying the slurry is appropriately pulverized to include the inorganic acid. However, the present invention is not limited to this, and a known method can be appropriately selected and used.

  Moreover, since the composition differs for each product marketed as lime nitrogen, the blending ratio of the acidic substance in the herbicide is appropriately determined according to the composition. More precisely, the alkalinity is measured for each product at the time of manufacture of the herbicide, and the blending ratio of the acidic substance is determined from the value, and the blending ratio of citric acid as the acidic substance is, for example, 1 g of lime nitrogen. The range is 1.8 g to 1.9 g.

  In addition, the neutralization by the acidic decomposition inhibitor in this Embodiment 1 is the neutral region which has the range which spreads the alkalinity which shows in the hydrolysis reaction process of lime nitrogen to weakly acidic side or weakly alkaline side on the basis of pH7. Means the reaction to be prepared.

  As described above, according to the first embodiment, acidic decomposition that suppresses decomposition of lime nitrogen and cyanamide generated as an intermediate product in the decomposition reaction process in which the lime nitrogen is decomposed in contact with water. Since it is configured to contain an inhibitor, this acidic decomposition inhibitor can neutralize the alkalinity exhibited in the decomposition reaction process of lime nitrogen and delay the reaction rate of the decomposition reaction itself. By slowing down the decomposition rate and allowing the superior weed control effect of cyanamide to act on weeds over a long period of time, there is an effect that weed growth can be prevented. In addition, according to the present invention, although the degradation rate of cyanamide is delayed by the degradation inhibitor, cyanamide is finally degraded to ammonia as a fertilizer via urea, so that it is well known for planted plants or cultivated plants. It can be used safely as a fertilizer, has no adverse effect on planted plants or the natural environment, and does not require a large labor cost.

Hereinafter, examples and comparative examples will be described.
Example 1.
A herbicide was produced by mixing a predetermined amount of citric acid with a predetermined amount of lime nitrogen. This herbicide, when sprayed in soil, comes into contact with moisture in the soil and exhibits pH 3.4.

Example 2
A herbicide was produced by mixing a predetermined amount of citric acid with a predetermined amount of lime nitrogen. This herbicide, when sprayed in soil, comes into contact with moisture in the soil and exhibits pH 9.0.

Example 3
A herbicide was produced by mixing a predetermined amount of citric acid with a predetermined amount of lime nitrogen. This herbicide, when sprayed in soil, comes into contact with moisture in the soil and exhibits pH 7.0.

Comparative Example A commercially available lime nitrogen that does not contain any of the above-described decomposition inhibiting substances was used as a comparative example.

  The compositions according to Examples 1 to 3 and the Comparative Example are brought into contact with moisture at a set temperature of 70 ° C. to initiate hydrolysis reaction of each lime nitrogen, and cyanamide contained in each example The concentration of was measured over time, and the measurement results are shown in FIG.

  As is clear from FIG. 1, the compositions of Examples 1 to 3 have a slower cyanamide decomposition rate than the composition of the comparative example (lime nitrogen only), and the stabilization of cyanamide is achieved. I understand that. In addition, each composition according to Example 2 and Example 3 is prepared in a neutral range than the composition according to Example 1, so that the degradation rate of cyanamide is slow and the stabilization of cyanamide is achieved. I understand.

It is a graph which shows the stability of the cyanamide in the herbicide (Example 1- Example 3) by one embodiment of this invention, and a comparative example.

Claims (1)

  A herbicide that is sprayed before weeds to prevent weeds from growing, and lime nitrogen and cyanamide produced as an intermediate product in the decomposition reaction in which this lime nitrogen is decomposed by contact with water. A herbicide containing a decomposition inhibitor that suppresses decomposition.

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