A target-variable hole-depth fertilization device for large-plant-spacing crops in the field

Abstract

A target variable hole depth fertilization device for large-plant-spacing crops in the field, comprising a frame, on which a main control box is installed. A fertilizer box is installed at the rear of the frame. A soil conductivity detection device, a front photoelectric sensor, a furrow opener, a soil covering device and a rear photoelectric sensor are installed at the lower part of the frame. The front photoelectric sensor is arranged directly above the soil conductivity detection device, and the rear photoelectric sensor is installed on the frame above the furrow opener. To sum up, the present invention can perform target variable hole depth fertilization operations according to the different growth states of each large-plant-spacing crop in the field, and has the advantages of strong adaptability, simple structure, high working efficiency and labor saving, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural machinery, and particularly relates to a target variable hole depth fertilizing device for large-row-spacing crops in the field. Background Technique

[0002] At present, fertilizing large-row-spacing crops in the fields of our country mainly relies on manual fertilizing, fertilizing by fertilizer spreaders, etc. Manual fertilizing is prone to uneven fertilizing amount and inaccurate judgment of the fertilizer requirement of crops. While fertilizing by fertilizer spreaders mostly fertilizes according to the prescription map information and cannot achieve on-demand fertilization for single crops, resulting in fertilizer waste and affecting crop growth. Summary of the Invention

[0003] The purpose of the invention is to provide a target variable hole depth fertilizing device for large-row-spacing crops in the field to solve the technical problems of uneven manual fertilizing and fertilizer waste caused by the inability of fertilizer spreaders to achieve on-demand fertilization for single crops.

[0004] To achieve the above purpose, the technical solution of a target variable hole depth fertilizing device for large-row-spacing crops in the field provided by the invention is as follows:

[0005] A target variable hole depth fertilizing device for large-row-spacing crops in the field includes a frame, on which a main control box is installed. A fertilizer box is installed behind the frame. A soil conductivity detection device, a front photoelectric sensor, a furrow opener, a soil covering device and a rear photoelectric sensor are installed at the lower part of the frame. The front photoelectric sensor is arranged directly above the soil conductivity detection device, and the rear photoelectric sensor is installed on the frame above the furrow opener.

[0006] The bottom of the fertilizer box has a fertilizer outlet, which is connected with a variable fertilizer distributor. The fertilizer discharging end of the variable fertilizer distributor is connected with a fertilizer conveying hose, and the lower end of the fertilizer conveying hose is provided with a fertilizer dropping mechanism.

[0007] The main control box is respectively connected with the soil conductivity detection device, the front photoelectric sensor, the rear photoelectric sensor, the variable fertilizer distributor and the fertilizer dropping mechanism for control.

[0008] Furthermore, the variable fertilizer distributor includes a fertilizer temporary storage box installed at the fertilizer outlet of the fertilizer box. The bottom of the fertilizer temporary storage box is a fertilizer discharging port, and the upper end of the fertilizer conveying hose is installed at the fertilizer discharging port of the fertilizer temporary storage box.

[0009] Mounting holes are respectively opened on the opposite side walls of the fertilizer temporary storage box, and a grooved wheel is rotatably installed in the two mounting holes. A fertilizer discharging motor is also installed on the fertilizer temporary storage box, and the fertilizer discharging motor is used to drive the grooved wheel to rotate.

[0010] The grooved wheel has several mounting bars, and all the mounting bars are evenly distributed on the circumferential outer surface of the grooved wheel. A fertilizer storage component is arranged between two adjacent mounting bars. The fertilizer storage component includes two bottom plates and two bottom plate sliding sleeves. One end of the bottom plate sliding sleeve is a hinged end, and the other end is an open end. A cavity is arranged inside the bottom plate sliding sleeve. The bottom plate can be slid into the cavity of the bottom plate sliding sleeve through the open end of the bottom plate sliding sleeve. The hinged ends of the two bottom plate sliding sleeves are respectively hinged on two adjacent mounting bars. One ends of the two bottom plates are hinged to each other, and the other ends of the two bottom plates are respectively inserted into the cavities of the two bottom plate sliding sleeves;

[0011] The variable fertilizer distributor further includes a variable control mechanism, and the variable control mechanism is used to synchronously push and pull the two bottom plates of all the fertilizer storage components so that the bottom plates move in the corresponding bottom plate sliding sleeves;

[0012] The variable control mechanism and the fertilizer discharging motor are respectively connected to the main control box for control.

[0013] Further, the variable control mechanism includes a linear stepper motor, a variable turntable and several groups of variable driving brackets;

[0014] The variable driving bracket is of a Y-shaped structure, and the variable driving brackets correspond to the fertilizer storage components one by one. The two forked ends of the variable driving bracket respectively abut and support on the two bottom plates of the fertilizer storage component, and a short shaft is fixed at the other end of the variable driving bracket;

[0015] A number of radial holes are formed in the end face of the grooved wheel. The radioactive holes are arranged along the radial direction of the end face of the grooved wheel, and all the radial holes are arranged in a circular array around the center of the end face of the grooved wheel;

[0016] The linear stepper motor is fixed on the side of the fertilizer temporary storage box through an outer housing. The variable turntable is located inside the outer housing. The variable turntable is connected to the main shaft of the linear stepper motor through a connecting member. The connecting member includes a telescopic column and a connecting sleeve. One end of the connecting sleeve is fixed to the main shaft of the linear stepper motor through a pin. A baffle is fixed in the middle of the connecting sleeve. The telescopic column is inserted into the connecting sleeve from the other end of the connecting sleeve, and a bearing is arranged between the telescopic column and the connecting sleeve. A spiral slide rail is formed on the telescopic column. The variable turntable has an inner hole, and a boss is fixed in the inner hole. The telescopic column is inserted into the inner hole, and the boss is located in the spiral slide rail;

[0017] A number of arc-shaped holes are formed in the variable turntable, and all the arc-shaped holes are arranged in a circular array around the center of the variable turntable;

[0018] The radial holes, the arc-shaped holes and the variable driving brackets are arranged in one-to-one correspondence. The short shafts of the variable driving brackets are sequentially inserted into the corresponding radial holes and arc-shaped holes.

[0019] Further, the fertilizer dropping mechanism includes a fertilizer dropping box. The top of the fertilizer dropping box is installed at the lower end of the fertilizer conveying hose. A fertilizer dropping port is opened at the bottom of the fertilizer dropping box. A fertilizer discharging blocking member is installed at the fertilizer dropping port. The fertilizer discharging blocking member includes a first circular ring body. A plurality of fertilizer discharging baffle plates are evenly distributed in the first circular ring body. A fertilizer discharging hole is formed between two adjacent fertilizer discharging baffle plates.

[0020] A fertilizer discharging wheel is rotatably installed on the upper surface of the fertilizer discharging blocking member. The fertilizer discharging wheel is located directly below the lower end of the fertilizer conveying hose. A fan blade is arranged inside the fertilizer discharging wheel. A motor installation shell is connected to the side of the fertilizer dropping box. A fertilizer dropping motor is installed inside the motor installation shell. The fertilizer dropping motor is used to drive the fertilizer discharging wheel to rotate. The main control box is connected to the fertilizer dropping motor for control.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention is a machine for target variable hole deep fertilization according to the fertilization amount required by a single plant during fertilization operations. When the front-end photoelectric sensor is used to detect the position of the plant in the present invention, the plant position information and the fertilization amount information required by the soil at that place are transmitted to the main control box. The main control box receives the signal and controls the variable fertilizer discharger to perform variable fertilizer discharge. The fertilizer falls into the fertilizer conveying hose and is temporarily retained. The rear-end photoelectric sensor detects the position of the crop plant in real time, and at the same time, the furrow opener opens a gully. When the rear-end photoelectric sensor detects the position of the plant again, the main control box receives the signal and controls the fertilizer dropping mechanism to apply fertilizer. The fertilizer falls into the gully, and the soil falls back under the action of the soil covering device to cover the fertilizer, and thus the target variable hole deep fertilization operation can be completed. The present invention can perform target variable hole deep fertilization operations according to the different growth states of each plant of the large-row-spacing crops in the field, and has the advantages of strong adaptability, simple structure, high working efficiency, and labor saving. Description of the Drawings

[0022] Figure 1 Is an axonometric view of a target variable hole deep fertilization device for large-row-spacing crops in the field;

[0023] Figure 2 Is a side view of a target variable hole deep fertilization device for large-row-spacing crops in the field;

[0024] Figure 3 Is a combined schematic diagram of a variable fertilizer discharger, a fertilizer conveying hose, and a fertilizer dropping mechanism;

[0025] Figure 4 Is a structural diagram removing the grooved wheel of the fertilizer storage component;

[0026] Figure 5 Is an installation schematic diagram of the fertilizer storage component;

[0027] Figure 6 Is a position schematic diagram of the variable turntable and the grooved wheel;

[0028] Figure 7 Is a structural diagram of the variable turntable;

[0029] Figure 8 It is a schematic structural diagram of a variable control mechanism;

[0030] Figure 9 It is a schematic diagram of the cooperation between the telescopic column and the variable turntable;

[0031] Figure 10 It is a schematic structural diagram of a fertilizer discharging baffle;

[0032] Figure 11 It is a schematic structural diagram of a fertilizer discharging wheel. Specific embodiments

[0033] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the accompanying drawings herein can be arranged and designed in various different configurations.

[0034] Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings below is not intended to limit the scope of the claimed present invention, but only represents the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0035] The present invention will be further described in detail below with reference to the embodiments.

[0036] Specific embodiment 1 of the device for target variable hole depth fertilization of large-plant-spacing crops in the field provided by the present invention:

[0037] As Figures 1-11 shown, in this embodiment, a device for target variable hole depth fertilization of large-plant-spacing crops in the field includes a frame 1, a main control box 2 is installed on the frame 1, a fertilizer box 3 is installed behind the frame 1, a soil conductivity detection device 4, a front photoelectric sensor 5, a furrow opener 6, a soil covering device 7 and a rear photoelectric sensor 8 are installed at the lower part of the frame 1, wherein the front photoelectric sensor 5 is arranged directly above the soil conductivity detection device 4, and the rear photoelectric sensor 8 is installed on the frame 1 above the furrow opener 6;

[0038] The bottom of the fertilizer box 3 has a fertilizer outlet, the fertilizer outlet is connected to a variable fertilizer discharger 9, the fertilizer discharging end of the variable fertilizer discharger 9 is connected to a fertilizer conveying hose 10, and the lower end of the fertilizer conveying hose 10 is provided with a fertilizer dropping mechanism 11;

[0039] The main control box 2 is respectively connected to the soil conductivity detection device 4, the front photoelectric sensor 5, the rear photoelectric sensor 8, the variable fertilizer discharger 9 and the fertilizer delivery mechanism 11 for control. The main control box 2 may be a PLC controller.

[0040] The present invention consists of a fertilizer box 3, a variable fertilizer discharger 9, a fertilizer delivery hose 10, a fertilizer drop mechanism 11 and a furrow opener 6 to form a variable hole depth fertilization system; the front-end photoelectric sensor 5, the rear-end photoelectric sensor 8 and the main control box 2 form a plant position detection system; the soil conductivity detection device 4 and the main control box 2 constitute a variable fertilization identification and control system, and the soil conductivity detection device 4 is a prior art. For details, refer to the "Design and Experiment of Vehicle-mounted Field Soil Conductivity Online Detection System" published in the journal "Journal of Agricultural Machinery" Volume 53, Issue 6, June 2022.

[0041] The variable hole depth fertilization system, the plant position detection system and the variable fertilization identification control system are all mounted on the frame 1 and connected to the tractor by a three-point suspension method. During operation, the soil conductivity detection device 4 is installed at the front end of the frame 1 to detect the amount of fertilizer required for the soil in real time. The front photoelectric sensor 5 is installed directly above the soil conductivity detection device 4. When the front photoelectric sensor 5 detects the plant position, the plant position information and the information on the amount of fertilizer required for the soil at that location are transmitted to the main control box 2. The main control box 2 receives the signal and controls the variable fertilizer discharger 9 to discharge the fertilizer in a variable manner, and the fertilizer falls into the fertilizer delivery hose 10 for temporary retention. The rear photoelectric sensor 8 detects the position of the crop plant in real time, and the furrow opener 6 opens a furrow. When the rear photoelectric sensor 8 detects the plant position again, the main control box 2 receives the signal and controls the fertilizer drop mechanism 11 to drop fertilizer. The fertilizer falls into the furrow, and the soil is covered by the soil cover 7 to cover the fertilizer, thereby completing the target variable hole depth fertilization operation.

[0042] The variable fertilizer discharger 9 includes a fertilizer temporary storage box 12, which is installed at the fertilizer outlet of the fertilizer box 3, the bottom of the fertilizer temporary storage box 12 is a fertilizer outlet, and the upper end of the fertilizer delivery hose 10 is installed at the fertilizer outlet of the fertilizer temporary storage box 12;

[0043] The opposite side walls of the fertilizer temporary storage box 12 are provided with mounting holes, and groove wheels 13 are rotatably mounted in the two mounting holes. A fertilizer discharge motor 14 is also mounted on the fertilizer temporary storage box 12, and the fertilizer discharge motor 14 is used to drive the groove wheel 13 to rotate; specifically, a rotating shaft is fixed on the groove wheel 13, and the rotating shaft is arranged along the axial direction of the groove wheel 13, and the main shaft of the fertilizer discharge motor 14 is drivingly connected with the rotating shaft;

[0044] The grooved wheel 13 has a number of mounting bars 15, and all the mounting bars 15 are evenly distributed on the circumferential outer surface of the grooved wheel 13. A fertilizer storage assembly 18 is arranged between two adjacent mounting bars 15. The fertilizer storage assembly 18 includes two bottom plates 16 and two bottom plate sliding sleeves 17. One end of the bottom plate sliding sleeve 17 is a hinged end, and the other end of the bottom plate sliding sleeve 17 is an open end. A cavity is arranged inside the bottom plate sliding sleeve 17. The bottom plate 16 can be slid into the cavity of the bottom plate sliding sleeve 17 through the open end of the bottom plate sliding sleeve 17. The hinged ends of the two bottom plate sliding sleeves 17 are respectively hinged on two adjacent mounting bars 15. One ends of the two bottom plates 16 are hinged to each other, and the other ends of the two bottom plates 16 are respectively inserted into the cavities of the two bottom plate sliding sleeves 17; Each group of fertilizer storage assemblies 18 is used for storing fertilizers. As shown in the figure, there are 6 fertilizer storage assemblies 18;

[0045] The variable fertilizer distributor 9 further includes a variable control mechanism, and the variable control mechanism is used to push and pull the two bottom plates 16 of all the fertilizer storage assemblies 18 synchronously, so that the bottom plates 16 move inside the corresponding bottom plate sliding sleeves 17;

[0046] The variable control mechanism and the fertilizer discharging motor 14 are respectively connected to the main control box 2 for control.

[0047] The variable fertilizer discharging principle of the variable fertilizer distributor 9 is as follows: By pushing the two bottom plates 16 of all the fertilizer storage assemblies 18 through the variable control mechanism, the bottom plates 16 move inside the corresponding bottom plate sliding sleeves 17, thereby changing the depth of the grooves of the fertilizer storage assemblies 18. The fertilizer storage assemblies 18 with different groove depths store different amounts of fertilizers. The fertilizer discharging motor 14 drives the grooved wheel 13 to rotate, so that the fertilizers in the fertilizer storage assemblies 18 are discharged into the lower fertilizer conveying hose 10, realizing the function of variable fertilizer discharging, avoiding the phenomenon of fertilizer jamming during variable fertilizer discharging, and preventing wear and leakage of fertilizers from affecting the fertilizer discharging accuracy.

[0048] In order to enable the variable control mechanism to push and pull the two bottom plates 16 of all the fertilizer storage assemblies 18 synchronously, the variable control mechanism includes a linear stepper motor 19, a variable turntable 20 and six groups of variable driving brackets 21;

[0049] The variable driving bracket 21 is of a Y-shaped structure, and the variable driving brackets 21 correspond to the fertilizer storage assemblies 18 one by one. The two forked ends of the variable driving bracket 21 respectively abut and support on the two bottom plates 16 of the fertilizer storage assembly 18, and a short shaft 22 is fixed to the other end of the variable driving bracket 21;

[0050] Six radial holes 23 are opened on the end face of the grooved wheel 13. The radioactive holes are arranged along the radial direction of the end face of the grooved wheel 13, and all the radial holes 23 are arranged in a circular array around the center of the end face of the grooved wheel 13;

[0051] The linear stepper motor 19 is fixed to the side of the fertilizer temporary storage box 12 through the outer housing 24. The variable turntable 20 is located inside the outer housing 24. The variable turntable 20 is connected to the main shaft of the linear stepper motor 19 through a connecting member. The connecting member includes a telescopic column 25 and a connecting sleeve 26. One end of the connecting sleeve 26 is fixed to the main shaft of the linear stepper motor 19 through a pin. A baffle 27 is fixed in the middle of the connecting sleeve 26. The telescopic column 25 is inserted into the connecting sleeve 26 from the other end of the connecting sleeve 26, and a bearing 28 is provided between the telescopic column 25 and the connecting sleeve 26. A spiral slide rail 29 is provided on the telescopic column 25. The variable turntable 20 has an inner hole, and a boss 100 is fixed in the inner hole. The telescopic column 25 is inserted into the inner hole, and the boss 100 is located in the spiral slide rail 29.

[0052] Six arc-shaped holes 30 are provided on the variable turntable 20, and all the arc-shaped holes 30 are arranged in a circular array around the center of the variable turntable 20.

[0053] The radial holes 23, the arc-shaped holes 30, and the variable drive brackets 21 are arranged in one-to-one correspondence. The short shafts 22 of the variable drive brackets 21 are sequentially inserted into the corresponding radial holes 23 and arc-shaped holes 30.

[0054] When receiving variable fertilizer discharging transmitted from the main control box 2, the linear stepper motor 19 starts. The linear motor pushes the telescopic column 25 through the connecting sleeve 26, so that the telescopic column 25 moves in the inner hole of the variable turntable 20. Since the spiral slide rail 29 on the telescopic column 25 cooperates with the boss 100 on the inner hole, the telescopic column 25 will drive the variable turntable 20 to rotate after moving. Due to the design of the six arc-shaped holes 30 on the variable turntable 20 and the six radial holes 23 on the end face of the grooved wheel 13, the variable turntable 20 drives the six variable drive brackets 21 to slide synchronously in six directions. And since the two bifurcated ends of the variable drive bracket 21 respectively abut and support on the two bottom plates 16 of the fertilizer storage assembly 18, the variable drive bracket 21 will synchronously push the two bottom plates 16 to move, realizing the adjustment of the depth of the grooves of the grooved wheel 13 fertilizer storage assembly 18.

[0055] It should be noted that during normal operation, the grooved wheel 13 rotates to drive the variable turntable 20 to rotate accordingly, and the telescopic column 25 rotates following the variable turntable 20. Since a bearing 28 is provided between the telescopic column 25 and the connecting sleeve 26, the rotation of the telescopic column 25 will not drive the connecting sleeve 26 and the linear stepper motor 19 to rotate.

[0056] The fertilizer dropping mechanism 11 includes a fertilizer dropping box 31, which is located immediately behind the furrow opener 6. The top of the fertilizer dropping box 31 is installed at the lower end of the fertilizer delivery hose 10. A fertilizer dropping opening is provided at the bottom of the fertilizer dropping box 31, and a fertilizer discharge blocker 101 is installed at the fertilizer dropping opening. The fertilizer discharge blocker 101 includes a first annular body 32, and a plurality of fertilizer discharge baffles 33 are evenly distributed in the first annular body 32, and a fertilizer discharge hole 34 is formed between two adjacent fertilizer discharge baffles 33.

[0057] A fertilizer wheel 35 is rotatably installed on the upper surface of the fertilizer discharging stopper 101. The fertilizer wheel 35 can be rotatably installed on the fertilizer discharging stopper 101 through an axis and a bearing. The fertilizer wheel 35 is located directly below the lower end of the fertilizer delivery hose 10. Fan blades 36 are arranged inside the fertilizer wheel 35, which can cooperate with the fertilizer discharging holes 34 between the fertilizer discharging baffles 33. A motor mounting shell 37 is connected to the side of the fertilizer dropping box 31, and a fertilizer dropping motor 38 is installed in the motor mounting shell 37. The fertilizer dropping motor 38 is used to drive the fertilizer discharging wheel 35 to rotate, and the driving method can adopt a gear transmission structure; the main control box 2 is controlled and connected with the fertilizer dropping motor 38.

[0058] When fertilizer falls from the fertilizer delivery hose 10, it can stay on the fertilizer discharge baffle 33. When the main control box 2 receives the signal detected by the rear-end photoelectric sensor 8, the main control box 2 controls the fertilizer discharge motor 38 to drive the fertilizer discharge wheel 35 to rotate a certain number of circles, so that the amount of fertilizer required by the corresponding crop can be fully discharged. Then the fan blade 36 stays on the fertilizer discharge hole 34, and the fertilizer discharge is closed.

Claims

1. A target-variable hole-depth fertilization device for large-plant-spacing crops in the field, characterized in that: It includes a frame, on which a main control box is installed. A fertilizer box is installed at the rear of the frame. A soil conductivity detection device, a front photoelectric sensor, a ditching tool, a soil covering tool and a rear photoelectric sensor are installed at the lower part of the frame. Among them, the front photoelectric sensor is arranged directly above the soil conductivity detection device, and the rear photoelectric sensor is installed on the frame above the ditching tool; The bottom of the fertilizer box has a fertilizer outlet, the fertilizer outlet is connected with a variable rate fertilizer applicator, the fertilizer discharging end of the variable rate fertilizer applicator is connected with a fertilizer conveying hose, and a fertilizer dropping mechanism is arranged at the lower end of the fertilizer conveying hose; The main control box is respectively connected with the soil conductivity detection device, the front photoelectric sensor, the rear photoelectric sensor, the variable rate fertilizer applicator and the fertilizer dropping mechanism for control. The variable rate fertilizer applicator includes a fertilizer temporary storage box, the fertilizer temporary storage box is installed at the fertilizer outlet of the fertilizer box, the bottom of the fertilizer temporary storage box is a fertilizer discharging port, and the upper end of the fertilizer conveying hose is installed at the fertilizer discharging port of the fertilizer temporary storage box; Installation holes are respectively opened on the opposite side walls of the fertilizer temporary storage box, a grooved pulley is rotatably installed in the two installation holes, and a fertilizer discharging motor is also installed on the fertilizer temporary storage box, and the fertilizer discharging motor is used to drive the grooved pulley to rotate; The grooved pulley has a number of installation bars, all the installation bars are evenly distributed on the circumferential outer surface of the grooved pulley, and a fertilizer storage component is arranged between adjacent two installation bars. The fertilizer storage component includes two bottom plates and two bottom plate sliding sleeves. One end of the bottom plate sliding sleeve is a hinged end, the other end of the bottom plate sliding sleeve is an open end, a cavity is arranged in the bottom plate sliding sleeve, and the bottom plate can be slidably inserted into the cavity of the bottom plate sliding sleeve through the open end of the bottom plate sliding sleeve. The hinged ends of the two bottom plate sliding sleeves are respectively hinged on adjacent two installation bars, one ends of the two bottom plates are hinged, and the other ends of the two bottom plates are respectively inserted into the cavities of the two bottom plate sliding sleeves; The variable rate fertilizer applicator also includes a variable control mechanism, and the variable control mechanism is used to synchronously push and pull the two bottom plates of all the fertilizer storage components so that the bottom plates move in the corresponding bottom plate sliding sleeves; The variable control mechanism and the fertilizer discharging motor are respectively connected with the main control box for control.

2. The variable-depth fertilizing device for large-spacing crops in the field according to claim 1, wherein: The variable control mechanism includes a linear stepper motor, a variable turntable, and several groups of variable drive brackets; the variable drive brackets are of Y-shaped structure, and the variable drive brackets correspond to the fertilizer storage components one by one. The two bifurcated ends of the variable drive brackets respectively abut and support on the two bottom plates of the fertilizer storage components, and a short shaft is fixed at the other end of the variable drive bracket; several radial holes are provided on the end face of the grooved pulley. The radial holes are arranged along the radial direction of the end face of the grooved pulley, and all the radial holes are arranged in an annular array around the center of the end face of the grooved pulley; the linear stepper motor is fixed on the side of the fertilizer temporary storage box through an outer housing, the variable turntable is located inside the outer housing, and the variable turntable is connected to the main shaft of the linear stepper motor through a connecting piece; the connecting piece includes a telescopic column and a connecting sleeve. One end of the connecting sleeve is fixed on the main shaft of the linear stepper motor through a pin. A baffle is fixed in the middle of the connecting sleeve. The telescopic column is inserted into the connecting sleeve from the other end of the connecting sleeve, and a bearing is arranged between the telescopic column and the connecting sleeve; a spiral slide rail is provided on the telescopic column. The variable turntable has an inner hole, and a boss is fixed in the inner hole. The telescopic column is inserted into the inner hole, and the boss is located in the spiral slide rail; several arc-shaped holes are provided on the variable turntable, and all the arc-shaped holes are arranged in an annular array around the center of the variable turntable; the radial holes, the arc-shaped holes, and the variable drive brackets are arranged in one-to-one correspondence, and the short shafts of the variable drive brackets are sequentially inserted into the corresponding radial holes and arc-shaped holes.

3. The variable hole depth fertilizing device for large-spacing crops in the field according to claim 2, wherein: The fertilizer dropping mechanism includes a fertilizer dropping box. The top of the fertilizer dropping box is installed at the lower end of the fertilizer conveying hose. A fertilizer dropping port is provided at the bottom of the fertilizer dropping box, and a fertilizer discharging blocking member is installed at the fertilizer dropping port. The fertilizer discharging blocking member includes a first annular body, and several fertilizer discharging baffles are evenly distributed in the first annular body. Fertilizer discharging holes are formed between two adjacent fertilizer discharging baffles; a fertilizer discharging wheel is rotatably installed on the upper surface of the fertilizer discharging blocking member. The fertilizer discharging wheel is located directly below the lower end of the fertilizer conveying hose. Fan blades are arranged inside the fertilizer discharging wheel. A motor installation shell is connected to the side of the fertilizer dropping box, and a fertilizer dropping motor is installed inside the motor installation shell. The fertilizer dropping motor is used to drive the fertilizer discharging wheel to rotate; the main control box is connected to the fertilizer dropping motor for control.

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