Seedling planting device and seedling planting method

Abstract

To provide a device capable of mechanically planting seedlings more easily, and to provide a seedling planting method.SOLUTION: A seedling planting device includes: a passage section for dropping seedlings in an inner space; a seedling holding section arranged above the passage section and temporarily holding seedlings; an expansion / contraction section arranged below the passage section, having an inner space communicated with the inner space of the passage section, and allowing an inner diameter to be expanded / contracted; and a control section connected to the seedling holding section and the expansion / contraction section, and satisfying a specific condition.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus capable of mechanically planting seedlings and a method for planting seedlings.

Background Art

[0002] Since the agricultural working population is decreasing year by year and the aging process is accelerating, there is a demand for the development of agricultural machinery that takes over heavy labor and plays an important role in improving productivity. However, the mechanization of transplanting seedlings of vegetables, flowers, etc. currently available on the market is lagging behind that of transplanting machines for rice production. The reasons include that there are various types of vegetables and flowers, even for the same vegetables, there are a wide variety of types, the cultivation forms may vary depending on the region, etc., there are a wide variety of delicate operations, and on the other hand, the cultivation of vegetables, flowers, etc. is relatively small-scale compared to rice cultivation, and considering the frequency of use, small and inexpensive machines are required.

[0003] For example, generally, machines have been developed to assist in the operation of making holes for planting seedlings in fields such as ridges (Non-Patent Documents 1, 2, etc.). Patent Document 1 discloses a seedling planting device having a claw body that is pierced into the ground and can be expanded. However, although these machines can make holes in the ground without bending the waist, they are far from being automated and are only for assisting manual work.

[0004] The machine described in Patent Document 1 is for transplanting soil-attached seedlings such as lettuce and cabbage. Patent Document 2 discloses an onion transplanting machine having a transplanting blade. Patent Document 3 discloses a seedling planting device provided with hole-forming means for forming holes for planting seedlings.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] [Non-Patent Document 1] Sanei Co., Ltd., “Holler (registered trademark)”, [online], [searched September 20, 2022], Internet<URL:http: / / www.san-eh.co.jp / holer / holer.html> [Non-Patent Document 2] Minoru Sangyo Co., Ltd., “Hand Planter”, [online], [Retrieved September 20, 2022], Internet<URL:https: / / www.agri-style.com / product_guide / detail.php?id=240> [Overview of the project] [Problems that the invention aims to solve]

[0007] As mentioned above, various machines have been developed for planting seedlings. These generally have claws that can be opened and closed to plant seedlings. When the claws are closed, they are driven into the ground and then expand to form a hole. In some machines, the seedling is transported into the claws in this state, and when the claws are withdrawn, the soil on the sides of the hole collapses, allowing the seedling to be planted. However, if seedlings are moved into the soil with holes already made, there is a risk that the holes may be too large and the seedlings may fall over inside the holes. Also, after moving the seedlings, the amount of soil that collapses from the sides may not be sufficient, and the seedlings may not be able to be stabilized, so it may be necessary to manually adjust the direction of the seedlings, add soil, or compact the soil around the seedlings. Therefore, the present invention aims to provide an apparatus and a method for planting seedlings that can be planted mechanically in a simpler manner. [Means for solving the problem]

[0008] The inventors diligently conducted research to solve the aforementioned problems. As a result, they discovered that by inserting a claw for forming a hole for planting seedlings into the soil, then partially opening it to transport the seedling, and then fully opening the claw before pulling it out, the size of the hole during the transfer of the seedling into the soil can be minimized, thereby stabilizing the seedling. Furthermore, the amount of soil that collapses from the sides increases, thus suppressing or reducing manual work after planting. This led to the completion of the present invention. The present invention is described below.

[0009] [1] A passage section through which seedlings are dropped in the interior, A seedling holding section is located above the aforementioned passage section and temporarily holds seedlings, An expandable / contractable section is located below the passage section, has an internal cavity that communicates with the internal cavity of the passage section, and is capable of expanding or contracting its internal diameter. It has a control unit connected to the seedling holding unit and the expansion / contraction unit, The control unit is a seedling planting device that satisfies the following conditions (1) to (3). (1) The expanding / contracting portion has the function of changing from a reduced diameter state to an expanded diameter state. (2) The expanding / contracting portion has the function of changing from an expanded diameter state to a contracted diameter state. (3) The seedling holder has a function to release the seedling when the expanding / contracting part is in an intermediate state (hereinafter referred to as the "intermediate state") that is neither the contracted state nor the expanded state. [2] The seedling planting apparatus according to [1], wherein the control unit further satisfies the following conditions (4) to (6). (4) In a specific first intermediate state belonging to the intermediate state, the function is to stop the operation of changing the expanding / contracting part from a reduced diameter state to an expanded diameter state. (5) After (4) above, the seedling holding unit has a function to control the seedling holding unit to release the seedling holding. (6) After the above (5), the function is to restart the operation of changing the expanding / contracting part from a reduced diameter state to an expanded diameter state. [3] The seedling planting apparatus according to [1] or [2], wherein the control unit further satisfies the following conditions (7) to (9). (7) In a specific second intermediate state belonging to the intermediate state, the seedling holding unit has a function to control the seedling holding unit to release the seedling. (8) After (7) and before the seedling reaches the expanding / contracting section, the function is to stop the operation of changing the expanding / contracting section from a reduced diameter state to an expanded diameter state. (9) After (8) and once the seedling has reached the expansion / contraction section, the function is to restart the operation of changing the expansion / contraction section from a reduced diameter state to an expanded diameter state. [4] The seedling planting apparatus according to any one of the above [1] to [3], further comprising a control unit that does not stop the operation of changing the expansion / contraction unit from a contracted state to an expanded state in the intermediate state. [5] The seedling planting device according to any one of the above [1] to [4], further having a function to allow at least a portion of the expanding and contracting portion to penetrate below the soil surface. [6] The seedling planting device according to [5], wherein the control unit is capable of acquiring information on the height of the soil surface below the expanding / contracting unit, and has a function to cause at least a part of the expanding / contracting unit to penetrate below the soil surface based on said information. [7] The seedling planting device according to any one of the above [1] to [6], wherein the expanding and contracting section has a plurality of opening and closing members having a base end side and a tip end side, and the expanding and contracting section is performed by the separation and approaching movements of the tip ends of the opening and contracting members.

[0010] [8] A passage section for dropping seedlings inside, A seedling holding section is located above the aforementioned passage section and temporarily holds seedlings, An expandable / contractable section is located below the passage section, has an internal cavity that communicates with the internal cavity of the passage section, and is capable of expanding or contracting its internal diameter. Using a seedling planting device having a seedling holding section and a control unit connected to the expansion / contraction section, The process of inserting the expanding / contracting portion into the ground and forming a hole by expanding its diameter from a fully closed state to an intermediate state, In the intermediate state, releasing the seedling from the seedling holding part and transferring the seedling to the hole through the passage part and the expansion / contraction part; Expanding the diameter of the expansion / contraction part from the intermediate state to the fully open state to expand the hole, and A method for planting seedlings including the step of pulling out the expansion / contraction part from the ground while in the fully open state.

Effect of the Invention

[0011] According to the seedling planting device of the present invention, manual operations such as correcting the direction of the seedling after planting, adding soil, and compacting the soil around the seedling can be reduced. Therefore, the present invention is extremely excellent industrially as it can reduce the load during seedling planting and improve productivity.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a schematic diagram showing the standby state of the seedling planting device according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of the seedling planting device according to the present invention in the preparation stage. [Figure 3] FIG. 3 is a schematic diagram of the seedling planting device according to the present invention in a state where at least the tip of the opening / closing member of the expansion / contraction part in the fully closed state is pierced into the ground. [Figure 4] FIG. 4 is a schematic diagram of the seedling planting device according to the present invention in a state where the opening / closing member is expanded in diameter from the fully closed state to the intermediate state in the soil. [Figure 5] FIG. 5 is a schematic diagram of the seedling planting device according to the present invention in the stage of transporting the seedling from the seedling holding part to the expansion / contraction part. [Figure 6] FIG. 6 is a schematic diagram of the seedling planting device according to the present invention in a state where the opening / closing member is expanded in diameter from the intermediate state to the fully open state in the soil. [Figure 7] FIG. 7 is a schematic diagram of the seedling planting device according to the present invention in a state where the expansion / contraction part with the opening / closing member in the fully open state is pulled out from the ground. [Figure 8] FIG. 8 is a flowchart showing an example of the processing procedure of the embodiment of the present invention. [Figure 9] Figure 9 is a flowchart showing an example of the processing procedure in an embodiment of the present invention. [Figure 10] Figure 10 is a flowchart showing an example of the processing procedure in an embodiment of the present invention. [Modes for carrying out the invention]

[0013] The seedling planting apparatus according to the present invention comprises at least a passage section, a seedling holding section, an expansion / contraction section, and a control section.

[0014] The passage section 1 is designed to allow seedlings to naturally fall from the seedling holding section 3 into the expansion / contraction section 4 within the air. The material of the passage section 1 is not particularly limited; for example, resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS) and polypropylene, or metals such as stainless steel can be used.

[0015] The size and shape of the passageway 1 can be adjusted as appropriate depending on the seedlings 2 to be planted. For example, the shape of the passageway 1 is preferably cylindrical or substantially cylindrical in order to suppress damage to the seedlings 2 during the fall. The size of the passageway 1 should be adjusted so that the seedlings 2 do not get stuck due to friction with the sides or overturn during the fall.

[0016] The seedling holding section 3 is located above the passage section 1 and is intended to temporarily hold the seedlings 2 before supplying them to the passage section 1.

[0017] The configuration of the seedling holding section 3 is not particularly limited as long as it can temporarily hold the seedling 2 without damaging it. For example, as shown in Figures 1 to 4, the seedling 2 may be held from the side by a clamping piece. In this case, the clamping piece may have a sensor function to prevent the seedling 2 from falling or being damaged during holding. Also, at least the portion of the clamping piece that contacts the seedling 2 may be covered with a soft porous resin such as soft polyurethane foam. The seedling 2 may have soil attached.

[0018] Alternatively, the seedling holding section 3 may be a seedling tray that holds multiple seedlings 2 with soil still attached. In this case, the seedlings 2 with soil still attached may be pushed out of the seedling tray into the passageway by a rod that can move back and forth using a drive element such as an electromagnet or solenoid.

[0019] The expanding / contracting section 4 is located below the passage section 1 and has an interior space that communicates with the interior space of the passage section 1. By expanding or contracting its interior diameter, it forms holes in the ground for planting seedlings 2 and for transporting seedlings 2 into the formed holes.

[0020] The expanding / contracting section 4 may have, for example, multiple opening / closing members 4a, each having a base end and a tip end, and the expanding / contracting section 4 is expanded and contracted by the separation and approaching movements of the tips of the opening / closing members 4a. The number of opening / closing members 4a can be, for example, one pair, i.e., two. Each opening / closing member 4a tapers towards its tip, and its tip is pointed enough to make a hole in the ground, and when the pair is put together, it forms a cone shape. The opening / closing mechanism 4b for opening and closing the opening / closing members 4a may, for example, normally have the opening / closing members 4a fully open by a spring or the like, but the opening / closing mechanism 4b can press each opening / closing member 4a from the outside to close it, or normally have the opening / closing members 4a fully closed by a spring or the like, but the opening / closing members 4a can be opened against the spring or the like by an electromagnet or wire.

[0021] The expandable / contractable section 4 of the present invention is characterized in that it can open the opening / closing member 4a to a fully open state (i.e., the expanded / contractable section 4 in an expanded diameter state) and to a fully closed state (i.e., the expanded / contractable section 4 in a contracted diameter state), as well as be able to expand to an intermediate state between the fully open state and the fully closed state. Such an intermediate state is a state in which the holding of the seedling 2 by the expandable / contractable section 4 can be released, but it is not in a fully open state. Specifically, the intermediate state is a state in which the degree of opening / closing of the opening / closing member 4a is 30% or more and 70% or less, with the degree of opening / closing in the fully open state being 0% and the degree of opening / closing in the fully open state being 100%. The degree of opening / closing is preferably 35% or more, more preferably 40% or more, preferably 65% ​​or less, and more preferably 60% or less.

[0022] The control unit 5 is connected to the seedling holding unit 3 and the expansion / contraction unit 4, and controls them. The control unit 5 may be a microcomputer attached to the seedling planting device as shown in Figures 1 to 7, or it may be a computer located outside the seedling planting device and wirelessly connected to it. Specifically, the control unit 5 controls the holding and release of seedlings in the seedling holding unit 3, and controls the opening and closing member 4a of the expansion / contraction unit 4.

[0023] The control unit 5 has the following functions (1) to (3). (1) Function to change the expanding / contracting part 4 from a contracted state to an expanded state. The control unit 5 controls the opening and closing mechanism 4b of the expansion / contraction section 4, changing the expansion / contraction section 4 from a contracted state to an expanded state. Specifically, the opening and closing member 4a expands the expansion / contraction section 4, which is in a fully closed state, to an intermediate state while it is stuck in the ground, thereby forming a hole in the ground and transferring the seedling 2 into the hole. Furthermore, by expanding the expansion / contraction section 4 from the intermediate state to a fully open state in the soil, the hole is further widened, making it easier for the soil to collapse from the sides when the expansion / contraction section 4 is pulled out of the ground.

[0024] (2) Function to change the expanding / contracting section 4 from an expanded state to a contracted state. As described in (1) above, when the expanding / contracting section 4 is pulled out of the ground, the opening / closing member 4a is in the fully open state. Therefore, the control unit 5 has the function of changing the expanding / contracting section 4 from an expanded state to a contracted state in order to form the next hole in the ground and to hold the seedling 2 until the hole is formed.

[0025] (3) A function to control the seedling holding unit 3 so as to release the holding of the seedling 2 in an intermediate state. In (1) above, the control unit 5 controls the seedling holding unit to release the seedling 2, particularly in the intermediate state. That is, since the distance between the pair of opening and closing members 4a of the expanding and contracting unit 4 in the intermediate state is narrower than in the fully open state, the tilting of the seedling 2 within the expanding and contracting unit 4 can be suppressed by controlling the seedling holding unit 3 so that the seedling 2 can be transferred to the expanding and contracting unit 4 in the intermediate state. Therefore, it is preferable to adjust the distance between the pair of opening and closing members 4a of the expanding and contracting unit 4 in the intermediate state according to the size and growth stage of the seedling 2 to be planted.

[0026] The control unit 5 preferably further has the following functions (4) to (6) (see Figure 8). (4) A function to stop the operation of changing the expansion / contraction part 4 from a reduced diameter state to an expanded diameter state in a specific first intermediate state which belongs to the intermediate state. (5) A function that controls the seedling holding unit 3 to release the seedling 2 after (4) above. (6) A function to restart the operation of changing the expanding / contracting part 4 from a contracted state to an expanded state after (5) above.

[0027] In other words, when the distance between the pair of opening and closing members 4a of the expanding and contracting section 4 reaches a predetermined value determined in advance according to the size of the seedling 2, the operation is stopped, and then the seedling is transferred from the seedling holding section 3 to the expanding and contracting section 4, thereby making it possible to more reliably stabilize the seedling 2 within the expanding and contracting section 4 while suppressing tilting. In other words, the specific first intermediate state is a state in which it is possible to transfer the seedling from the planting member to the hole formed in the soil and the seedling is supported by the planting member. Next, the hole is widened by further expanding the diameter of the expanding and contracting section 4 from the intermediate state.

[0028] The control unit 5 preferably has the following additional functions (7) to (9) instead of (4) to (6) (see Figure 9). (7) A function that controls the seedling holding unit 3 to release the holding of the seedling 2 in a specific second intermediate state which belongs to the intermediate state. (8) A function to stop the operation of changing the expansion / contraction section 4 from a reduced diameter state to an expanded diameter state after (7) and before the seedling 2 reaches the expansion / contraction section 4. (9) A function to restart the operation of changing the expansion / contraction section 4 from a contracted state to an expanded state after (8) and when the seedling 2 has reached the expansion / contraction section 4.

[0029] In other words, when the seedling holding unit 3 releases the seedling 2, the expansion / contraction unit 4 is still in the process of moving from the fully closed state to a specific second intermediate state. The control unit 5 adjusts the timing of when the seedling holding unit 3 releases the seedling so that the seedling 2 reaches the expansion / contraction unit 4 when the expansion / contraction unit 4 reaches or just before reaching the specific second intermediate state. As a result, the time it takes for the expansion / contraction unit 4 to move from the fully closed state to the specific second intermediate state overlaps with the time it takes for the seedling 2 to be transferred from the seedling holding unit 3 to the expansion / contraction unit 4, making it possible to further improve the overall seedling planting efficiency. The specific second intermediate state is a state in which, like the specific first intermediate state, it is possible to transfer the seedling from the planting member to a hole formed in the soil and the seedling is supported by the planting member.

[0030] The control unit 5 preferably has the following additional functions (10) to (11) instead of (4) to (9) (see Figure 9). (10) Function to prevent the operation of changing the expansion / contraction section 4 from a contracted state to an expanded state from an intermediate state (11) A function that controls the seedling holding unit 3 to release the holding of the seedling 2 in a specific third intermediate state which belongs to the intermediate state.

[0031] In other words, the expansion / contraction unit 4 does not stop in a specific third intermediate state during the process from the contracted state to the expanded state, but the control unit 5 controls the expansion / contraction unit 4 and the seedling holding unit 3 to release the seedling 2 from the seedling holding unit 3 in the specific third intermediate state. As a result, it becomes possible to plant the seedling 2 more efficiently. The specific third intermediate state is a state in which, like the specific first intermediate state, it is possible to transfer the seedling from the planting member to a hole formed in the soil and the seedling is supported by the planting member.

[0032] The seedling planting device according to the present invention preferably further has a function to allow at least a portion of the expanding / contracting section 4 to penetrate below the soil surface. By expanding the diameter while at least a portion of the expanding / contracting section 4 is penetrated below the soil surface, it becomes possible to form a hole in the ground for planting the seedling 2. The depth to which the expanding / contracting section 4 penetrates the ground can be appropriately adjusted according to the size and growth stage of the seedling 2 to be planted.

[0033] In order to allow at least a portion of the expanding / contracting section 4 to penetrate below the soil surface, it is preferable that the seedling planting device has a mechanism for moving at least the seedling holding section 3, the passage section 1, and the expanding / contracting section 4 up and down. Hereinafter, the unit including the seedling holding section 3, the passage section 1, and the expanding / contracting section 4 may be referred to as a seedling transplanting unit.

[0034] The control unit 5 is capable of acquiring information on the height of the soil surface below the expansion / contraction unit 4, and it is preferable to insert at least a portion of the expansion / contraction unit 4 to a predetermined depth below the soil surface based on this information.

[0035] The seedling planting device according to the present invention may have other components for assisting or automating seedling planting, in addition to the seedling transplanting unit and a mechanism for moving the seedling transplanting unit up and down. Examples include a depth sensor and drive wheels. As described above, the depth sensor can measure the distance between the expansion / contraction unit 4 and the soil surface below it and send this information to the control unit 5. Furthermore, the depth sensor can recognize the shape and height of the ridges from the image of the ground acquired by the depth sensor, and drive the drive wheels so that the center position of the ridges coincides with the center position of the seedling planting device, thereby advancing the seedling planting device or correcting its position.

[0036] The seedling planting method according to the present invention includes the steps of: inserting the expandable / contractible part 4 into the ground and expanding its diameter from a fully closed state to an intermediate state to form a hole; releasing the seedling 2 from the seedling holding part 3 in the intermediate state and transferring the seedling 2 to the hole through the passage part 1 and the expandable / contractible part 4; expanding the expandable / contractible part 4 from the intermediate state to a fully open state to enlarge the hole; and pulling out the expandable / contractible part 4 from the ground while it remains in the fully open state (see Figure 10). The present invention will be described step by step below with reference to the drawings, but the present invention is not limited to the above or the following specific examples.

[0037] (1) Hole forming process In this process, the expanding / contracting section 4 of the seedling planting device is thrust into the ground, and a hole is formed by expanding its diameter from a fully closed state to an intermediate state.

[0038] In the seedling planting method according to the present invention, the fully open and retractable section is pulled out of the ground at the end of the process. Therefore, in the standby state of the seedling planting apparatus according to the present invention (Figure 1) before the start of the method of the present invention, the opening and closing member 4a of the opening and closing section 4 is in the fully open state.

[0039] Next, in the preparation stage of the seedling planting device (Figure 2), the opening and closing mechanism 4b is used to fully close the opening and closing member 4a in order to thrust the expanding and contracting section 4 into the ground 6.

[0040] Next, the seedling transplanting unit is lowered, and at least the tip of the opening / closing member 4a of the expanding / contracting section 4, which is in the fully closed state, is thrust into the ground (Figure 3). At this time, the depth of the expanding / contracting section 4 in the ground is predetermined according to the size and growth stage of the seedlings and is controlled by the control unit 5. Furthermore, the opening / closing mechanism 4b expands the opening / closing member 4a in the soil from the fully closed state to an intermediate state (Figure 4). This creates a hole in the ground 6 for planting the seedlings.

[0041] (2) Seedling transfer process In this process, when the expansion / contraction section 4 is in an intermediate state, the seedlings 2 are released from the seedling holding section 3 and transferred to the hole through the passage section 1 and the expansion / contraction section 4 (Figure 5). At this time, the distance between the opening and closing members 4a of the expansion / contraction section 4 in the intermediate state is predetermined according to the size and growth stage of the seedlings, so that the tilting of the seedlings 2 within the cavity of the expansion / contraction section 4 and the hole is suppressed.

[0042] (3) Full opening process of the expansion / contraction section In this process, the opening / closing member 4a of the expanding / contracting section 4 is expanded from an intermediate state to a fully open state by the opening / closing mechanism 4b, thereby widening the hole (Figure 6). Even during this process, the tilting of the seedling is suppressed by the inner side surface of the expanding / contracting section 4.

[0043] (4) Drawing process In this process, the expanding / contracting section 4 is pulled out of the ground 6 while it is fully open (Figure 7). As a result, more soil collapses from the sides of the hole compared to the conventional method, stabilizing the planted seedlings, thus reducing the need for additional work such as adding or compacting soil after planting the seedlings. [Explanation of Symbols]

[0044] 1: The passage section through which seedlings are dropped from the interior. 2: Seedlings to plant 3: Seedling holder section for temporarily holding seedlings 4: Expandable / contractable section with adjustable inner diameter 4a: Opening and closing member for the expansion and contraction section 4b: Opening and closing mechanism of the expansion / contraction section 5: Control unit for controlling at least the seedling holding unit and the expansion / contraction unit. 6: The ground where seedlings should be planted

Claims

1. A passage section through which seedlings are dropped inside, A seedling holding section is located above the aforementioned passage section and temporarily holds seedlings, An expandable / contractable section is located below the passage section, has an internal cavity that communicates with the internal cavity of the passage section, and is capable of expanding or contracting its internal diameter. It has a control unit connected to the seedling holding unit and the expansion / contraction unit, The control unit is a seedling planting device that satisfies the following conditions (1) to (3). (1) The expanding / contracting portion has the function of changing from a reduced diameter state to an expanded diameter state. (2) The expanding / contracting portion has the function of changing from an expanded diameter state to a contracted diameter state. (3) The seedling holder has a function to release the seedling when the expanding / contracting part is in an intermediate state (hereinafter referred to as the "intermediate state") which is neither the contracted state nor the expanded state.

2. The seedling planting apparatus according to claim 1, wherein the control unit further satisfies the following conditions (4) to (6). (4) In a specific first intermediate state belonging to the intermediate state, the device has a function to stop the operation of changing the expanding / contracting part from a reduced diameter state to an expanded diameter state. (5) After (4) above, the seedling holding unit has a function to control the seedling holding unit to release the seedling. (6) After the above (5), the function is to restart the operation of changing the expanding / contracting part from a reduced diameter state to an expanded diameter state.

3. The seedling planting apparatus according to claim 1, wherein the control unit further satisfies the following conditions (7) to (9). (7) In a specific second intermediate state belonging to the intermediate state, the seedling holding unit has a function to control the seedling holding unit to release the seedling. (8) After (7) and before the seedling reaches the expansion / contraction section, the function is to stop the operation of changing the expansion / contraction section from a contracted state to an expanded state. (9) After (8) and when the seedling has reached the expansion / contraction section, the function is to restart the operation of changing the expansion / contraction section from a reduced diameter state to an expanded diameter state.

4. The seedling planting apparatus according to claim 1, further comprising a control unit that does not stop the operation of changing the expansion / contraction unit from a contracted state to an expanded state in the intermediate state.

5. The seedling planting device according to any one of claims 1 to 4, further comprising the function of allowing at least a portion of the expanding and contracting portion to penetrate below the soil surface.

6. The seedling planting apparatus according to claim 5, wherein the control unit is capable of acquiring information on the height of the soil surface below the expanding / contracting unit, and has a function to cause at least a part of the expanding / contracting unit to penetrate below the soil surface based on said information.

7. The seedling planting device according to claim 1, wherein the expanding and contracting section has a plurality of opening and closing members having a base end side and a tip end side, and the expanding and contracting section is performed by the separation and approaching movements of the tip ends of the opening and closing members.

8. A passage section through which seedlings are dropped inside, A seedling holding section is located above the aforementioned passage section and temporarily holds seedlings, An expandable / contractable section is located below the passage section, has an internal cavity that communicates with the internal cavity of the passage section, and is capable of expanding or contracting its internal diameter. Using a seedling planting device having a seedling holding section and a control unit connected to the expansion / contraction section, The process of inserting the expanding / contracting portion into the ground and forming a hole by expanding its diameter from a fully closed state to an intermediate state, In the aforementioned intermediate state, the seedlings are released from the seedling holding section and transferred to the hole through the passage section and the expansion / contraction section. The process of expanding the diameter of the expanding / contracting portion from the intermediate state to the fully open state, thereby widening the hole, and A method for planting seedlings, which includes the step of pulling out the expandable / contractible part from the ground while it is in the fully open state.

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