Weeding and weed control equipment

Abstract

To provide an environmentally friendly weeding and weed prevention implement excellent in weeding and weed prevention effects, which achieves labor saving in work and maintains effects over a long period of time.SOLUTION: A weeding and weed prevention implement includes a vehicle 2 that can travel, and a pair of electrodes 3 and 3 disposed in a state of protruding toward the ground, and opposed to each other with a predetermined separation distance in between, on a surface facing the ground of the vehicle 2, and gives an electric stimulus to a plant 4 interposed between the pair of electrodes 3 and 3 by an electric action generated between the pair of electrodes 3 and 3. As an another form, a weeding and weed prevention implement includes a vehicle 2 that can travel, an application electrode 10 disposed on the surface facing the ground of the vehicle 2, and a power reception part 11 provided in the vehicle 2, whose tip is grounded, and gives an electric stimulus to a plant that comes in contact with the application electrode 10 by an electric current flowing at least with the application electrode 10, the plant 4, and the power reception part 11 as a closed circuit by the plant 4 coming into contact with the application electrode 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a weeding / weed control machine that uses electrical stimulation to control weeds. [Background technology]

[0002] Labor-saving and cost-effective weed control is required in all areas, including agriculture and construction sites. Common methods for weed control include chemical control using pesticides and physical control using brush cutters. The former, chemical control, poses environmental concerns, including impacts on ecosystems, potential drift into nearby areas, and potential impacts on water systems due to underground runoff. There are also concerns about the impact of inhaling pesticide ingredients on the human body. Furthermore, the latter, physical control, requires more frequent weeding because weeds quickly regrow from the remaining roots underground after cutting the stems and leaves above ground. This increases labor costs and poses challenges, such as the risk of heatstroke during intense heat and the health hazards posed by the vibrations and noise of brush cutters.

[0003] In addition to the chemical and physical control methods mentioned above, electrical control methods have been developed in recent years, in which high voltage is discharged or applied to weeds. This electrical control method involves applying a high voltage between electrodes and applying the discharged current to the weeds to electrically stimulate them, or by directly contacting the weeds with electrodes to which a high voltage has been applied, thereby destroying their cells and tissues and causing them to wither and die.

[0004] As an example of such an electrical control method, Patent Document 1 below discloses an electric weeding machine equipped with a high-voltage generator as an electric discharge weeding device that simultaneously uses the discharge or application of high voltage or static electricity to wither and kill plants and to cut or crush them. This electric weeding machine is equipped with an upper cutting blade connected to a positive electrode led from the high-voltage generator and a lower cutting blade connected to a negative electrode led from the high-voltage generator, and when weeds come into contact with the cutting blades and are cut, a spark discharge occurs, and the weeds that are subjected to this discharge have their root, stem and leaf cells destroyed and are crushed and removed.

[0005] Furthermore, Patent Document 2 listed below discloses a weeding machine that includes a vehicle body, a traveling device that supports the vehicle body so that it can travel, and a discharge device that is provided below the vehicle body and is capable of discharging electricity toward plants growing on the ground that are to be removed. The discharge device has an insulating outer shell and a discharge unit that is covered by the outer shell and discharges electricity toward the ground, and the discharge unit is composed of an application electrode that is provided facing downward with respect to the conductive axis of the outer shell and multiple plate-shaped power receiving units attached to the inner surface of the outer shell, and when electricity discharges in the gap between the tip of the application electrode and the power receiving unit, electricity discharge products resulting from the electricity discharge pass through through holes provided between the power receiving units of the outer shell and exit the outer shell. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-186324 [Patent Document 2] Japanese Patent Publication No. 2020-80732 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the weeding device disclosed in Patent Document 1 has the risk of electric shock due to electrical leakage, making it impossible to ensure the safety of the operator. In addition, although a discharge device is attached to the brush cutter, it is expected that the frequency of mowing will be reduced, so as a person must still move around to mow the grass with the brush cutter, as in the past, so it does not reduce labor and has other drawbacks, such as increased labor costs.

[0008] Furthermore, in the weeding machine disclosed in Patent Document 2, when discharge products resulting from discharge occurring in the gap between the applying electrode and the power receiving part are discharged onto weeds, only the products that pass through the through holes and emerge outside the shell act on the weeds, so the amount of discharge that acts on the weeds is small, making it impossible to effectively electrically stimulate many weeds, and there are also problems with consuming a large amount of power to ensure a larger amount of discharge.

[0009] Therefore, the main object of the present invention is to provide an environmentally friendly weeding and weed prevention machine that is excellent in weeding and weed prevention effects, reduces labor required for work, and maintains its effects over a long period of time. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention according to claim 1 provides a vehicle that can run, and a pair of electrodes that are disposed on a surface of the vehicle that faces the ground in a state where they protrude toward the ground and are disposed opposite each other with a predetermined distance between them, A weeding / weed prevention machine is provided, characterized in that an electrical stimulus is given to a plant located between the pair of electrodes by the electrical action generated between the pair of electrodes.

[0011] The invention described in claim 1 above is a first embodiment of the weeding / weed control machine of the present invention, in which a pair of electrodes are arranged facing each other on a mobile vehicle, and an electrical action is generated between the electrodes to provide an electrical stimulus to plants located between the pair of electrodes. This type of weed control using a pair of electrodes mounted on a mobile vehicle reduces labor. Furthermore, plants exposed to the electrical stimulus undergo irreversible cell perforation, causing the cellular contents to leak out and ensure death. The electrical stimulus reaches the roots of the plants and damages them, resulting in a long-lasting herbicidal effect. Furthermore, the electrical action generated between the pair of electrodes also affects seeds held by the plants and seeds that have fallen to the ground, thereby suppressing the germination rate of these seeds and providing a weed control effect. This type of weed control using electrical stimulation is environmentally friendly, eliminating the risk of pesticides scattering or leaking into groundwater. The electrical action may include any one or a combination of two or more of the following: an electric field generated between a pair of electrodes; a current flowing from one electrode to the other through at least the plant when the plant comes into contact with the electrode; and a discharge occurring in the gap between the electrode and the plant.

[0012] As the present invention according to claim 2, there is provided a weeding / weed prevention machine according to claim 1, wherein the pair of electrodes extend along the direction of travel of the vehicle and consist of flat plates arranged parallel to and spaced apart in a direction perpendicular to the direction of travel.

[0013] In the invention described in claim 2, the pair of electrodes is specifically formed of parallel flat plates extending in the direction of vehicle travel and spaced apart in a direction perpendicular to the direction of travel. This generates a three-dimensional electric field between these parallel flat plates, and current flows to plants through the plants and soil in contact with the electrodes, so that electrical stimulation can be reliably given to many plants, further improving the effects of weed control and weed prevention.

[0014] As a third aspect of the present invention, the vehicle comprises a vehicle body and a running body, There is provided a weeding / weed prevention machine according to claim 1 or 2, wherein the pair of electrodes is provided under the vehicle body.

[0015] In the invention as set forth in claim 3, the pair of electrodes is provided under the body of the vehicle, so that the risk of electric shock can be reduced and the safety of the work can be improved.

[0016] The present invention according to claim 4 provides the weeding / weed-prevention machine according to any one of claims 1 to 3, wherein the electric field strength between the pair of electrodes is 1.1 kV / cm or more.

[0017] In the invention described in claim 4 above, an electric field of a predetermined electric field strength or greater is applied between the pair of electrodes to give a strong electrical stimulus to the plant, causing irreversible cell perforation and thereby ensuring the plant's death.

[0018] Claim 5 As the present invention, the vehicle is capable of self-propelling. 4 Any of the weeding / weed prevention machines is provided.

[0019] The above claims 5 In the described invention, the vehicle is self-propelled, so it can remove weeds automatically, further reducing the labor required for weed control work. [Effects of the Invention]

[0020] As explained in detail above, the present invention makes it possible to provide an environmentally friendly weeding and weed prevention machine that is excellent in weeding and weed control effects, reduces labor required for work, and maintains its effects over a long period of time. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a side view showing a weeding / weed prevention machine 1 according to a first embodiment. [Figure 2] FIG. 2 is a view taken along the line II-II in FIG. [Figure 3] FIG. 10 is a side view of a weeding / weed prevention machine 1 according to a modified example. [Figure 4] FIG. 1 is a schematic diagram of a PFN type single pulse generating circuit. [Figure 5] FIG. 1 is a schematic diagram of the experimental setup. [Figure 6] 10 is a graph showing the relationship between the total weight of lettuce leaves and the applied pulse electric field strength. [Figure 7] 1 is a graph showing the percentage increase or decrease in the total weight of lettuce leaves. [Figure 8] FIG. 1 is a cross-sectional view showing a weeding / weed-prevention machine 1 according to a second reference embodiment. [Figure 9] FIG. 9 is a view taken along the line IX-IX in FIG. 8. [Figure 10] FIG. 1 is a schematic diagram of an experimental device for current flow experiment 1. [Figure 11] FIG. 1 is a schematic diagram (part 1) of the experimental device for current flow experiment 2. [Figure 12] FIG. 2 is a schematic diagram (part 2) of the experimental device for current flow experiment 2. [Figure 13] 1 is a cross-sectional view showing a weeding / weed prevention machine 1 equipped with a sprinkler device 20. FIG. [Figure 14] 1 is a cross-sectional view showing a weeding / weed-prevention machine 1 towed by or automatically following a water sprinkler vehicle 21. FIG. [Figure 15] 1 is a cross-sectional view showing a weeding / weed prevention machine 1 equipped with a rotary power receiving unit 11. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] [First embodiment] As shown in Figures 1 and 2, a weeding and weed control machine 1 according to a first embodiment of the present invention comprises a drivable vehicle 2 and a pair of electrodes 3, 3 that are arranged on the surface of the vehicle 2 facing the ground in a state where they protrude toward the ground and are arranged opposite each other with a predetermined distance between them, and the electrical action generated between the pair of electrodes 3, 3 gives an electrical stimulus to a plant 4 located between the pair of electrodes 3, 3.

[0024] The vehicle 2 comprises a body 5 and a running body 6 that supports the body 5 so that it can run. The vehicle 2 is preferably remotely controlled or automatically self-propelled to reduce the labor required for weeding and weed prevention work, but it may also be driven by a driver in a driver's seat provided in the body 5, or towed by or automatically followed by another vehicle. In this way, weeds can be controlled by the pair of electrodes 3, 3 provided in the mobile vehicle 2, which significantly reduces the labor required for weeding compared to when a person moves around with a brush cutter.

[0025] The vehicle body 5 is equipped with a drive device such as an engine or a motor that drives the traveling body 6, as well as a power supply device (battery) that supplies electricity to the electrodes 3 and the drive device. By providing the power supply device detachably, a fully charged power supply device can be used to control weeds over a wide area for a long period of time.

[0026] The running body 6 may be a tire-wheel structure consisting of at least front and rear wheels provided at the front and rear of the vehicle body 5, as in the illustrated example, or may be a caterpillar-type structure.

[0027] The pair of electrodes 3, 3 is provided on the lower part of the vehicle body 5 and is arranged to protrude from the underside of the vehicle body 5 toward the ground. The pair of electrodes 3, 3 is composed of parallel flat plates extending along the traveling direction of the vehicle 2 and spaced apart in the width direction of the vehicle 2, which is perpendicular to the traveling direction. The electrode 3 is formed in a flat plate shape having a predetermined length in the traveling direction of the vehicle 2 and a predetermined height in the height direction, so that almost the entire surface of the flat plate exerts an electrical effect. The pair of electrodes 3, 3 are provided on the left and right sides of the vehicle 2 at a distance, so that plants 4 pass between these electrodes 3, 3 as the vehicle 2 travels. As shown in FIG. 1, since the electrode 3 has a predetermined length in the traveling direction of the vehicle 2, a predetermined section along the traveling direction becomes an application section E in which an electrical effect is exerted.

[0028] The electrical action can include any one or a combination of two or more of the following: an electric field generated between the pair of electrodes 3, 3; a current flowing from one electrode 3 to the other electrode 3 through at least the plant 4 in contact with the electrode 3; and an electric discharge generated in the gap between the electrode 3 and the plant 4.

[0029] The length of the electrode 3 in the traveling direction of the vehicle is preferably 5 to 50 cm, and more preferably 10 to 30 cm, and the height is preferably 3 to 40 cm, and more preferably 5 to 20 cm.

[0030] Plants 4 passing between the pair of electrodes 3, 3 are subjected to electrical stimulation by the electrical action generated between these electrodes. When the electrical action is an electric field, the high electric field strength causes irreversible cell perforation, resulting in the loss of cell contents and cell destruction, which impedes nutrient absorption and eventually leads to death. The electrical stimulation applied to the exposed leaves and stems of the plant 4 reaches the roots underground and severely damages them, resulting in a long-lasting herbicidal effect. Furthermore, the electrical action generated between the pair of electrodes 3, 3 also affects seeds held by the plant 4 and seeds that have fallen to the ground, thereby suppressing the germination rate of these seeds and thereby achieving a herbicidal effect. Weed control using such electrical stimulation is environmentally friendly compared to chemical control methods, as it does not involve the risk of pesticides being dispersed or leaking into groundwater.

[0031] As described in the non-patent literature below, it has been confirmed that applying a certain electric field to plants promotes their growth through the electroporation effect. However, electric field strengths higher than this are too strong for plants, causing irreversible cell perforation and resulting in the loss of cellular contents, which has adverse effects on plants. Based on the experimental results described in the non-patent literature below, the electric field strength that causes irreversible cell destruction in plants should be 1.1 kV / cm or higher, preferably 1.5 kV / cm or higher.

[0032] The pair of electrodes 3, 3 are each connected to a power supply unit (not shown) mounted on the vehicle body 5 by an electric cable, and one electrode 3 is positively charged and the other electrode is negatively charged, and a high voltage is applied to them.

[0033] The lower end of the electrode 3 may be in contact with the ground or may be spaced above the ground. That is, the lower end of the electrode 3 may be at approximately the same height as the lower end of the wheel, or may be higher. Alternatively, as shown in FIG. 3, the lower end of the electrode 3 may be located below the lower end of the wheel so that the lower end of the electrode 3 is buried in the ground. It is preferable to position the lower end of the electrode 3 as close to the ground as possible, and preferably to position the electrode 3 so that the lower end is buried in the ground, because this makes it easier to apply an electric field not only to the stems and leaves of plants but also to the roots.

[0034] In the side view of the vehicle 2 shown in Figure 1, the lower edge of the electrode 3 is shown as a straight line that is approximately parallel to the ground. However, as shown in Figures 3(B) and (C), it is preferable to form the electrode 3 in an arc shape that bulges out in the center toward the ground in the direction of travel, or in an inclined shape that protrudes downward more toward the rear of the vehicle in the direction of travel than toward the front, as this makes it easier for the electrode 3 to overcome obstacles such as stones and allows the vehicle 2 to travel smoothly. In addition, the portion of the lower edge that is formed in an arc shape or an inclined shape that is close to the ground is partially buried in the ground, making it easier to apply an electric field or other electrical effect to plant roots.

[0035] Electroporation, a technique for perforating cells using a pulsed electric field, has been known for some time and has recently begun to be applied to the agricultural field. In a non-patent document (Wang Douyan, Goto Takahiro, Yoshida Takashi, Namihira Takao, Akiyama Hidenori, Fujiwara Toshiyuki, Sato Daigo; "Lettuce Growth Control Using Pulsed Electric Fields," Institute of Electrical Engineers of Japan Pulsed Power Study Group Materials, PPT-12, March 2012, pp. 13-16), the inventors of the present application reported the results of an experiment conducted to examine the relationship between the strength of the applied pulsed electric field and the yield of lettuce grown on hydroponic lettuce, a major variety cultivated in plant factories, with the aim of controlling plant growth by applying a pulsed electric field to the roots of the plant, thereby shortening the number of days required for agricultural crop cultivation, which is one solution for promoting the widespread use of plant factories. The following is an outline of the experiment.

[0036] 1. Experimental Method <Sample to which pulse electric field is applied> In the experiment, a pulsed electric field was applied to the roots of hydroponic lettuce (variety: Early Impulse). For cultivation, lettuce seeds were sown in seedling pots filled with culture soil and grown in the pots until the planting period (approximately 20 days after sowing), after which the seedling pots were immersed in liquid fertilizer and the liquid fertilizer was circulated. The seedling pots were made of thin resin and had multiple slits spaced around the periphery on the lower side. The liquid fertilizer was absorbed through these slits and the grown roots extended outward. The lettuce leaves were harvested approximately 40 days after sowing.

[0037] In the experiment, the plants were transferred to an incubator (M-230F, manufactured by Taitec Corporation) at the time of planting and cultured for approximately 20 days until harvest. During this time, a pulsed electric field application experiment was conducted. Culture conditions were a temperature of 20-21°C, humidity of 30-95%, fluorescent lighting 24 hours a day, and illuminance of 6,800-10,000 lux. Within the incubator, seedling pots were placed in plastic trays soaked in liquid fertilizer, and a constant amount of liquid fertilizer was maintained by adding more liquid fertilizer to replace the amount lost by evaporation within the incubator.

[0038] <Pulse electric field generator> A PFN (Pulse Forming Network) type single pulse generator circuit was used to generate the pulsed electric field. An outline is shown in Figure 4. The PFN was connected in seven stages, with an inductance of 2 μH and a capacitance of 2.7 nF for each stage. The theoretical output pulse width was 400 ns and the power supply characteristic impedance was 10 Ω. The characteristic impedance was calculated from the conductivity (approximately 1 ms / cm) of the liquid fertilizer used in hydroponic lettuce cultivation and the electrode shape for applying the electric field. By connecting a matched load of 10 Ω to the input end of the PFN, the reflected wave generated at the load end was absorbed on the input side, resulting in a single pulse output.

[0039] A DC high-voltage power supply (PS / EW40R15.0-10, manufactured by GLASSMAN HIGH VOLTAGE) was used to charge the PFN. In addition, a negative pulse voltage was applied to the load to prevent discharge between the electrodes.

[0040] The voltage waveform applied between the electrodes was measured using a high-voltage probe (P6015A-R3, manufactured by Tektronix), and the current to the load was measured using a current probe (Pearson current monitor, Model 110, manufactured by Pearson Electronics) with an oscilloscope (TDS3054B, manufactured by Tektronix).

[0041] To apply a pulsed electric field to the lettuce roots, stainless steel parallel-plate electrodes (80 mm diameter, disk-shaped) were fixed to the opposing walls of an acrylic container. To vary the applied pulsed electric field strength, several acrylic containers of different lengths were created, and the parallel-plate electrodes were attached to the container corresponding to the desired electric field strength.

[0042] <Method for applying a pulsed electric field and method for evaluating the growth of lettuce> The pulsed electric field application began around the 20th day before the planting period, and was applied once daily in the morning until the harvest day. The pulsed electric field application procedure was to first fill the reactor with new liquid fertilizer, then remove the lettuce plants from the incubator and place them between parallel plate electrodes so that the entire seedling pot was immersed in the liquid fertilizer (see Figure 5). After applying the pulsed electric field to the lettuce roots, the seedling pot was removed from the reactor and returned to the incubator. The liquid fertilizer used during the electric field application in the reactor was discarded and not used for lettuce cultivation.

[0043] Based on the findings of the preliminary experiment, the frequency of the pulsed electric field applied to the lettuce roots was determined to be 1 Hz, the number of applications was determined to be 100, and the electric field strength was varied from 0.2 to 2.0 kV / cm. Taking into consideration the biological balance of the lettuce itself, three samples were used for each parameter. In addition, control samples were treated in the same way as the pulsed electric field-applied samples, and the electric field strength was set to 0.0 kV / cm (no electric field applied).

[0044] Growth was evaluated by comparing the total weight of the harvested lettuce leaves with the samples for each electric field application parameter and the control sample. At harvest, the lettuce leaves were cut to the height of the top edge of the seedling pot, and the total weight of the leaves was measured using an electronic balance (PL3002, Mettler-Toledo). To assess reproducibility, the experiment was performed three times, and the average value was used.

[0045] 2. Experimental Results Figure 6 shows the dependence of lettuce leaf weight on the applied pulsed electric field strength at harvest. Table 1 and Figure 7 show the percentage increase or decrease in the average lettuce leaf weight at each electric field strength compared to the control, with the control set at 100%. Figures 6, 7, and Table 1 clearly demonstrate that lettuce growth can be controlled by applying a pulsed electric field to the lettuce roots. Furthermore, there is an optimum electric field strength for achieving growth promotion, and applying an electric field that is too strong can inhibit growth. Under the experimental conditions of this study (pulse duration of 400 ns, 1 Hz, 100 pulses applied once daily after planting), the optimum electric field strength for promoting lettuce leaf growth was 0.5–1.0 kV / cm, while a strong electric field of 2.0 kV / cm or higher inhibited leaf growth. Furthermore, at 0.4 kV / cm, the greatest growth promotion effect was observed, resulting in an approximately 20% increase in production compared to when no pulsed electric field was applied.

[0046] Furthermore, at harvest, the lettuce roots of the plants exposed to 0.4 kV / cm, which had the greatest growth promotion effect, were thicker and longer, and had a higher density of root hairs than the control plants.On the other hand, the plants exposed to 2.0 kV / cm, which showed growth inhibition, had less developed roots than the control plants, and the tips of the roots were brittle and crumbled when touched with a finger.

[0047] As shown in Table 1 and Figure 7, the electric field strength at which the total weight of lettuce leaves decreases compared to the control plant is approximately 1.1 kV / cm or higher, and at electric field strengths above 1.5 kV / cm, the reduction rate is particularly significant, exceeding 20%.

[0048] [Table 1]

[0049] [ Reference Second embodiment The present invention Reference8 and 9, the weeding / weed control machine 1 according to the second embodiment includes a travellable vehicle 2, an application electrode 10 arranged on the surface of the vehicle 2 facing the ground, and a power receiving unit 11 that is attached to the vehicle 2 and has a grounded tip, and when a plant 4 comes into contact with the application electrode 10, a current flows through a closed circuit of at least the application electrode 10 → plant 4 → power receiving unit 11, thereby providing an electrical stimulus to the plant 4 that is in contact with the application electrode 10. The path along which the current flows is application electrode 10 → plant 4 → power receiving unit 11 when the plant 4 is short-circuited between the application electrode 10 and the power receiving unit 11, and is application electrode 10 → plant 4 → soil → power receiving unit 11 when the plant 4 comes into contact with the application electrode 10 and the power receiving unit 11 is grounded at a position separated from the plant 4.

[0050] The application electrode 10 is made up of one or more linear or rod-shaped members, and is provided on the underside of the vehicle body 5 in a state where it protrudes downward, or in a state where it is spaced downward from the underside of the vehicle body 5 and stretched approximately parallel to the underside. Specifically, it is preferable to use a wire or a linear material such as a wire so that it deforms appropriately when a plant 4 passes over it and naturally returns to its original position after the plant 4 passes over it. When the application electrode 10 is arranged in a state where it protrudes downward, its upper end is fixed to the vehicle body 5 and its lower end is a free end that hangs down toward the ground, and the lower end does not come into contact with the ground but is arranged above the ground at a predetermined distance.

[0051] A plurality of the application electrodes 10, preferably about 2 to 10, are arranged at predetermined intervals in the width direction of the vehicle 2, and in the example shown in Fig. 9, five application electrodes 10, 10... are arranged between the left and right wheels 6, 6. By arranging a plurality of the application electrodes 10 in the width direction, the chances that the application electrodes 10 will come into contact with the plants 4 increase, making it easier for current to flow through the plants 4.

[0052] The power receiving unit 11 is made of a conductive metal member, and preferably a chain, wire, rod, plate, or the like is used. Alternatively, as will be described in the following section on current flow experiment 2, a rotating roller, caterpillar, or the like may be used. One end of the power receiving unit 11 is attached to the body 5 of the vehicle 2, and the other end is disposed so as to be in contact with the ground. This allows the vehicle 2 to constantly drag the other end of the power receiving unit 11 as it travels. The other end of the power receiving unit 11 may be disposed so as to be in contact with the ground, or may be disposed so as to be buried underground.

[0053] The application electrode 10 and the power receiving unit 11 are preferably arranged so that the application electrode 10 is arranged at the front in the traveling direction of the vehicle 2, and the power receiving unit 11 is arranged behind it. Alternatively, the application electrode 10 and the power receiving unit 11 may be arranged side by side in a direction perpendicular to the traveling direction of the vehicle (vehicle width direction).

[0054] [Electrical experiment 1] An experiment on passing electricity to plants was carried out using an experimental device that simulated the above-mentioned weeding / weed prevention machine 1. This experiment on passing electricity 1 assumed that when a plant comes into direct contact with one of the two electrodes, a current flows from this electrode through the plant and soil to the other electrode, giving the plant an electrical stimulus. In the following explanation, Reference Based on the weeding / weed control machine 1 according to the second embodiment, the one electrode is described as the application electrode 10 and the other electrode as the power receiving section 11, but in the weeding / weed control machine 1 according to the first embodiment, the same effect is produced when current flows from one electrode 3 to the other electrode 3 through the plant 4 or soil.

[0055] As shown in Figure 10, the experimental apparatus consisted of a cultivation pot containing three plants 4 (sorghum), a horizontally stretched linear application electrode 10, a power receiving unit 11 inserted into the soil from the bottom of the cultivation pot, and a power supply unit that generated pulsed power. The experimental conditions were a power output of 20 kV (open load) and a pulse frequency of 1 kpps. The height of the application electrode 10 relative to the plants 4 was set to two different heights: 65 mm and 30 mm above the soil surface. The experimental method involved applying a current to the application electrode 10 while it was in contact with the plants 4 for approximately one minute, and observing the state of the plants 4. This experiment was performed on two of the three plants in the same cultivation pot, and then the plants were continuously cultivated in an incubator for one week, during which the state of the plants 4 was observed.

[0056] As a result, after the current was applied, the plant 4 broke at the part that had been in contact with the application electrode 10, and black scorch was observed at the broken part. Partway through the period when the current was applied, discharge was confirmed visually from the part of contact between the application electrode 10 and the plant 4. After about a week, it was confirmed that the two plants 4 that had been applied with electricity had died visually, and some of the roots had become assimilated with the soil and could not be recovered, but the one plant 4 that had not been applied with electricity continued to grow. The above phenomenon was the same whether the height of the application electrode 10 was 65 mm or 30 mm.

[0057] [Electrical experiment 2] An experiment on passing electricity to plants was carried out using an experimental device that simulated the above-mentioned weeding / weed prevention machine 1. This experiment on passing electricity 2 assumed that when a plant comes into direct contact with one of the two electrodes, a current flows from this electrode through the plant and soil to the other electrode, giving the plant an electrical stimulus. In the following explanation, Reference Based on the weeding / weed control machine 1 according to the second embodiment, the one electrode is described as the application electrode 10 and the other electrode as the power receiving section 11, but in the weeding / weed control machine 1 according to the first embodiment, the same effect is produced when current flows from one electrode 3 to the other electrode 3 through the plant 4 or soil.

[0058] The experimental apparatus consists of a cultivation pot containing one plant 4 (sorghum), a horizontally stretched linear application electrode 10, a power receiving unit 11 installed at a predetermined position according to the experimental conditions, and a power supply unit that generates pulsed power.

[0059] As a preliminary experiment, a current experiment was conducted for Pattern 1-1 shown in FIG. 11(A) and Pattern 1-2 shown in FIG. 11(B). In Pattern 1-1, the power receiving unit 11, which is a metal rod, was inserted vertically into the soil to a depth of 30 mm from its tip, a horizontal distance L of 30 mm from the application electrode 10. The load resistance value at this time was small, approximately 3 kΩ. In Pattern 1-2, the power receiving unit 11, which is a metal rod, was placed in the air outside the cultivation pot, a horizontal distance L of 60 mm from the application electrode 10. The load resistance value at this time was significantly higher than that of Pattern 1-1, at several MΩ or more. The experimental conditions were a power output of 20 kV (open load) and a pulse frequency of 1 kpps. The height of the application electrode 10 relative to the plant 4 was 15 mm above the soil surface. As a result, in pattern 1-1, current flowed through a closed circuit from the application electrode 10 to the plant 4 to the soil to the power receiving part 11, and discharge was visually confirmed from the contact point between the application electrode 10 and the plant 4 partway through the current-carrying period, and after a certain period of time (several days), the plant 4 died. On the other hand, in pattern 1-2, no current flowed (or even if it did, it was below the detection sensitivity of the measuring device), and the plant 4 continued to grow. From these results, it is clear that to ensure the plant dies, it is necessary to pass a larger current through the plant.

[0060] In this experiment, plant 4 (sorghum) was grown in pots in well-moistened soil, so the closed circuit formed between the power supply and the load had a low resistance. On the other hand, in actual grassland with overgrown weeds, the resistance increases depending on the moisture content of the soil, the distance between the application electrode 10 and the power receiving unit 11, and the ground surface area of ​​the power receiving unit 11. If this resistance becomes excessive, a closed loop like the one in pattern 1-2 above can be expected. Therefore, it is important to devise a way to allow a larger current to flow in grassland.

[0061] To ensure a larger current flows, an experiment was conducted to confirm the effect of watering. The experiment measured and compared the resistance of the earth before and after watering the grass. An insulation resistance meter was used as the measuring instrument, and the tips of the test leads on the earth side and lead side were inserted vertically into the soil, 10 cm apart horizontally. Before watering and after watering, the resistance of the earth was measured and compared. 2 When the resistance was measured before and after watering, it was found to have decreased from 14 kΩ before to 5 kΩ after watering. This confirmed that watering can reduce the earth resistance, allowing a larger current to flow.

[0062] Next, to increase the current flow, a current flow experiment was conducted by varying the distance L between the applying electrode 10 and the power receiving unit 11 and the ground contact area A of the power receiving unit 11. The experimental setup is shown in Figure 12. The power receiving unit 11 may be any metal body with a tip, preferably a flat plate. In this experiment, a crimp terminal with a ring-shaped tip was used. The horizontal distance between the power receiving unit 11 and the applying electrode 10 was L. When the power receiving unit 11 was inserted into the soil (as shown in the example), both the front and back surfaces of the crimp terminal came into contact with the soil. When the power receiving unit 11 was in contact with the soil surface, the contact surface with the soil was one side of the crimp terminal. Therefore, if the ground contact area A when the power receiving unit 11 was in contact with the soil surface was 1, the ground contact area A when the power receiving unit 11 was inserted into the soil was 2. The experimental conditions were a power supply output of 20 kV (open load) and a pulse frequency of 1 kpps. As shown in Table 2, current experiments were conducted for patterns 2-1 to 2-3 in which the height H from the soil surface to the application electrode 10, the horizontal distance L from the application electrode 10 to the power receiving part 11, and the ratio of the ground contact area A of the power receiving part 11 were changed. The applied voltage for pattern 2-1 was 10 kV and 16 A, while the applied voltage for patterns 2-2 and 2-3 was 6 to 7 kV and 10 A.

[0063] [Table 2]

[0064] For comparison with these electrically treated plants, we also prepared plants treated with a commercially available herbicide (BASF Japan, BASTA liquid). 10 ml of a 100-fold diluted herbicide was applied dropwise evenly to the surface of the aboveground parts of the plants.

[0065] As a result, herbicide-treated plants began to wilt one day after treatment, and by the fifth day, they had begun to wilt, mainly around the area where the solution was dripped. All electrically treated plants began to wilt by the second day after treatment, and by the fifth day, the above-ground parts below the wire electrode contact point had begun to wilt. In both treatments, the above-ground parts had wilted by the seventh to tenth day. For the above-ground parts of Plant 4, electrically treated plants showed the same effect as herbicide-treated plants. For the underground parts of Plant 4, electrically treated plants became so brittle that they were difficult to separate from the soil, while herbicide-treated plants thinned but maintained their shape. Since the herbicide used in this experiment primarily contained ingredients that kill the above-ground parts of plants, it is likely that the shape of the underground parts (roots) was maintained. In any case, while herbicides only partially kill weeds, electrical treatment is effective in killing both above-ground and underground parts by creating a closed loop current circuit (allowing current to flow through the plant's roots as well). Furthermore, in patterns 2-2 and 2-3 in which the distance L between the applying electrode 10 and the power receiving portion 11 was reduced and the ground contact area A of the power receiving portion 11 was increased, this tendency was more pronounced than in pattern 2-1.

[0066] From the above experiments, it was found that in order to achieve plant death by electrical treatment (pulsed power application treatment), it is desirable to pass a larger current by reducing the resistance value (impedance) of the soil as much as possible in the closed circuit formed by the application electrode 10 → plant 4 → soil → power receiving unit 11.

[0067] The above experiments clearly show that the following three methods are effective for reducing the resistance (impedance) of soil. (1) Watering the soil (2) The horizontal distance between the applying electrode 10 and the power receiving unit 11 is kept as short as possible. (3) The grounding area of ​​the power receiving unit 11 is made as large as possible. Hereinafter, specific embodiments in which the above three items are applied to the weeding / weed-prevention machine 1 according to the present invention will be illustrated.

[0068] (1) Watering the soil In order to reduce the resistance value of the soil, it is preferable to water the soil before applying an electrical stimulus to the plants 4 with the weeding / weed prevention machine 1 according to the present invention. The timing of watering may be any time before the application electrode 10 comes into contact with the plants 4 and a current flows through the plants 4, but it is preferable to water the soil when it is sufficiently moist before the current is passed through the soil.

[0069] As a method of watering the soil, water can be sprayed in advance on the area to be weeded or prevented using a hose or a water sprinkler truck. In order to allow a larger current to flow to the plants 4 by passing electricity through the water sprinkled on the soil before it penetrates deep into the ground, a water sprinkler device 20 may be provided at the front of the weeding / weed prevention machine 1 as shown in Figure 13, or the weeding / weed prevention machine 1 may be towed by or automatically follow a water sprinkler truck 21 as shown in Figure 14.

[0070] (2) The horizontal distance between the applying electrode 10 and the power receiving unit 11 is kept as short as possible. In order to reduce the resistance value of the soil, it is preferable to install the application electrode 10 and the power receiving unit 11 close to each other and spaced horizontally apart enough to prevent an electrical short circuit between them. For this reason, it is preferable to install both the application electrode 10 and the power receiving unit 11 together in a specific location such as the rear or front of the vehicle body 5, and multiple sets of application electrodes 10 and power receiving units 11 installed close to each other may be installed on the vehicle body 5.

[0071] (3) The grounding area of ​​the power receiving unit 11 is made as large as possible. To increase the contact area between the power receiving unit 11 and the ground, it is possible to provide multiple power receiving units 11. For example, multiple power receiving units 11 can be connected in parallel to one application electrode 10. This makes it easier for the current applied by the application electrode 10 to flow from the soil through the plant 4 to the multiple power receiving units 11.

[0072] On the other hand, if multiple power receiving units 11 grounded to the ground are provided in this way, the power required to move the weeding / weed prevention machine 1 increases due to contact resistance with the ground, which may pose a problem of having to increase the size of the power unit. For this reason, in order to increase the contact area of ​​the power receiving units 11 while reducing contact resistance with the ground, rotating rollers or caterpillars may be used as the power receiving units 11, as shown in Figure 15. [Explanation of symbols]

[0073] 1...weeding / weed prevention machine, 2...vehicle, 3...electrode, 4...plant, 5...vehicle body, 6...traveling body, 10...applying electrode, 11...power receiving part

Claims

1. The device comprises a vehicle that can travel, and a pair of electrodes that are disposed on a surface of the vehicle that faces the ground in a state where they protrude toward the ground and are disposed opposite each other with a predetermined distance between them, A weeding / weed prevention machine characterized in that an electrical action generated between the pair of electrodes gives an electrical stimulus to plants located between the pair of electrodes.

2. 2. The weeding and weed prevention machine according to claim 1, wherein the pair of electrodes comprises parallel flat plates extending in the direction of travel of the vehicle and spaced apart in a direction perpendicular to the direction of travel.

3. The vehicle comprises a vehicle body and a running body, 3. The weeding / weed prevention machine according to claim 1, wherein the pair of electrodes is provided on a lower part of the vehicle body.

4. 4. The weeding / weed prevention machine according to claim 1, wherein the electric field strength between the pair of electrodes is 1.1 kV / cm or more.

5. 5. The weeding and weed prevention machine according to claim 1, wherein the vehicle is self-propelled.

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