JPS62259533A - Soil sterilizing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a soil sterilization method for protecting crops from diseases, and more particularly to an electrical sterilization method.

[Prior Art] Conventionally, as a method of electrically exterminating nematodes parasitic on the roots of crops, a method of applying a high voltage pulse to the soil near the roots of the crops is known (Japanese Patent Application Laid-Open No. 5111-1999). 218533
issue).

The above method attempts to exterminate nematodes without consuming a large amount of power or having an adverse effect on crops by passing a pulsed shock current of about several milliamperes.

[Problems to be Solved by the Invention] By the way, although the conventional method described in Section 2 does indeed have an extremely high exterminating effect on nematodes, it does not have a significant exterminating effect on bacteria. Not yet. Therefore, there is a problem in that it is not possible to prevent crop diseases caused by bacteria in the soil.

[Means for Solving the Problems] To explain the means for solving the above-mentioned problems, the present invention takes a method of passing a DC pulse current of 50 mA or more through the soil.

In the present invention, the pulse current is supplied to the soil by, for example, as shown in FIG.
Embed electrodes a and 2b, and electrode 2a.

This can be done by applying a high voltage pulse between 2b. The sterilization of the soil 1 according to the present invention can be carried out before or after planting the crops 3, but when carried out after the planting of the crops 3, the sterilization of the soil 1 is focused on the area around the crops 3.
It is preferable to arrange both electrodes 2a and 2b so as to sandwich the electrodes 2a and 2b.

The distance between the electrodes 2a and 2b and the voltage applied between the electrodes 2a and 2b are adjusted so that the required amount of pulse current can flow. If the distance between the electrodes 2a and 2b becomes too short, the range that can be sterilized becomes too narrow and practicality is lost.

If the distance between electrodes 2b is made too long, the voltage applied between electrodes 2a and 2b must be extremely high in order to flow the required amount of pulse current, which increases the burden on the device. Therefore, a voltage of 300 to 20,000 V, preferably a pulse voltage of 1,000 to 10,000 V is applied between electrodes 2a and 2b, and the distance between electrodes 2a and 2b is adjusted so that the required amount of pulse current is obtained at that time. It is preferable to do so.

In the present invention, as another method of supplying pulsed current to the soil 1, as shown in FIG.
2b facing each other and buried in soil 1, both electrodes 2a, 2b
As shown in FIG. 3, a rod-shaped electrode 2b is buried inside a cylindrical electrode 2a such as a mesh or a perforated plate, and a high voltage pulse is applied between the two electrodes 2a and 2b. There is a method of applying high voltage pulses to In this way, a relatively wide area can be sterilized at once. When performing the method shown in Figure 2 after planting crop 3, the crop 3 is sandwiched between both electrodes 2a and 2b, and when performing the method shown in Figure 3 after planting crop 3, the rod-shaped electrode 2b is placed between the electrodes 2a and 2b. It is preferable to locate them nearby so that the area around the crops 3 can be sufficiently sterilized.

In particular, when sterilizing the soil 1 according to the present invention after planting the crops 3, one electrode 2a is buried in the soil 1, the other electrode 2b is brought into contact with the crops 3, and both electrodes are A high voltage pulse can also be applied between 2a and 2b. In this way, sterilization near the crop 3 becomes even more reliable. In addition, when sterilizing a wide area before planting crops 3, as shown in FIG.
b, and the trolley 4 can be pulled around by a tractor or the like while applying a high voltage pulse between the electrodes 2a and 2b.

In the present invention, the pulse current applied to the soil l is 50! QA
or more, preferably 100mA or more,
Optimally, it is 150 mA or more. If the pulse current value is too low, bacteria cannot be sufficiently exterminated and the necessary sterilizing effect cannot be obtained. Here, in this specification, bacteria include actinobacteria, fungi, etc. in addition to eubacteria.

When a pulse current having the above value is applied, this acts as a strong shock current on the bacteria in the soil 1. and,
Since it is a shock current, even a relatively small current can damage or stop the activity of bacteria.

In addition, since the current is a pulsed current and the time for generating the current is very short, even if it is carried out after planting the crops 3, it is unlikely to have an adverse effect on the crops 3.

There is no particular limit to the upper limit of the pulse current value as long as it is before the planting of Crop 3, but considering the impact on the human body, the impact on Crop 3 when carried out after the planting of Crop 3, the reduction in power consumption, etc. It is preferable to set it to about 10100O or less.

In the present invention, it is preferable to generate the pulsed current flowing through the soil 1 to several tens of DC pulses. Even if the current is continuously generated, bacteria cannot be exterminated by the shock current, and sufficient sterilization is not achieved. Not only is it not effective, but after planting,
A negative impact on Crop 3 also occurs. In addition, continuous supply of current is
Not only does this result in a large amount of power consumption, but the electrodes 2a and 2b are contaminated in a short time by the electrolyte, making it difficult to conduct electricity.

The pulsed current supplied in the present invention may be supplied without changing the positive or negative of the high voltage pulse to be applied, but for example, the pulsed current may be supplied by alternating the positive or negative every -times and reversing the current direction. Good too.

Particularly in the case of dry soil, it may be difficult to generate a pulse current of the above-mentioned value. Therefore, it is preferable that an electrolyte solution that does not adversely affect the crops 3 is sprinkled on the soil 1 before the pulse current is supplied. Examples of the electrolyte solution include an aqueous solution of ammonium sulfate or ferrous sulfate. Moreover, a mixture of multiple types of electrolytes can be used.

[Example] Example 1 Linear bacteria were inoculated on agar in a petri dish with a diameter of 10 cm, and 5
Cultured for 1 day. Four of these petri dishes are arranged in a row, and a copper wire is placed across the agar in adjacent petri dishes, and electrodes are inserted into the agar in the petri dishes at both ends, and both electrodes touch the agar in each petri dish. The petri dishes were connected in series via copper wires.

30 cc of an aqueous solution of 0.01% by weight ammonium sulfate was added to each petri dish, and a direct current pulse current was passed between both electrodes at a rate of 112 times per 5 seconds. This pulsed current supply is repeated for 15 minutes by repeatedly supplying the pulsed current for 5 seconds and then pausing for 5 seconds.This is repeated 4 times at 15 minute intervals, and each time the current value, p)I ,Culture medium(
Agar) temperature and number of bacteria were measured.

As a power source, AC 100 V is rectified to DC, and approximately 30 V
A voltage boosted to 00V was used, and the voltage was applied in a constant direction without switching the positive and negative sides. Furthermore, the current value of the pulsed current was determined by measuring the current value on the surface of the agar, and the number of bacteria was determined as the average value of all petri dishes.

The number of bacteria before treatment was approximately 1×108.

The results are shown in Table 1.

Example 2 Measurements were carried out in the same manner as in Example 1, except that the ammonium sulfate aqueous solution was replaced with a 0.01% by weight ferrous sulfate aqueous solution.

Note that the number of bacteria before treatment was 1.3×10 8 .

The results are shown in Table 2.

Example 3 The concentration of the ammonium sulfate aqueous solution added to the Petri dish was set to 0.
Measurements were carried out for each concentration in the same manner as in Example 1, except that the concentration was changed to 0.01.0.05.0.1.0.2% by weight and the pulse current treatment was performed three times.

The number of bacteria before treatment was 1.3×108.

The results are shown in Table 3.

Example 4 The concentration of the ferrous sulfate aqueous solution added to the petri dish was set to 0.01.
Measurements were carried out for each concentration in the same manner as in Example 1, except that the concentration was changed to 0.05, 0.1, and 0.2% by weight, and the pulse current treatment was performed three times.

The bacterial count before treatment was SX108.

The results are shown in Table 4.

15 Comparative Example 1 Measurements were carried out in the same manner as in Example 1, except that an aqueous electrolyte solution such as ammonium sulfate or ferrous sulfate was not added to the Petri dish and the pulse current value was lowered.

Note that the number of bacteria before treatment was 2×10 8 .

The results are shown in Table 5.

[Effects of the Invention] According to the present invention, soil can be sterilized;
Crop diseases caused by bacteria can be safely and reliably prevented.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams each showing an example of a method of supplying pulsed current to soil. 1: soil, 2a, 2b: electrode, 3: crop,
4; Trolley.

Claims (1)

[Claims] 1) A soil sterilization method characterized by passing a direct current pulse current of 50 mA or more through the soil.