METHOD FOR APPLYING A SPRAY TO AGRICULTURAL AREA

Description

State of the art

[0001] The invention relates to a method for applying a spraying agent to an agricultural area by means of at least one spray nozzle unit of an agricultural spraying device, as well as a control unit and an agricultural spraying device for applying a spraying agent according to the preamble of the independent claims.

[0002] Algorithms for plant row detection are well-established. In most cases, these algorithms are based on camera images taken from a field machine. These images are captured at steep angles and show as large an area as possible to simplify plant row detection.

[0003] Furthermore, methods for weed detection and classification are known which are carried out using high-resolution small images and preferably without tilt angles in order to obtain sufficient image resolution for the detection of small plant objects.

[0004] To ensure accurate plant recognition and compensate for any interfering factors, successive images or evaluation areas within the images must overlap. The higher the speed of the machine, the higher the repetition rate must be to achieve the selected or predetermined overlap between evaluation regions sequentially in the direction of travel.

[0005] US Patent 10 721 859 B2 discloses a method for applying a pesticide.

[0006] From DE 10 2018 217 742 A1, a method for applying a plant protection product is known in which an evaluation section has a predetermined constant length, which is shorter than the length of a corresponding recorded field section. The position of the predetermined evaluation section within the field section is selected depending on the driving speed of the spraying device. Disclosure of the invention

[0007] The present invention relates to a method for applying a spraying agent to an agricultural area by means of at least one spray nozzle unit of an agricultural spraying device, comprising the steps of: Capturing a field section of the agricultural area using at least one optical detection unit to obtain image information of the field section with a depth T(image) in the direction of travel of the spraying device; identifying plants in an image evaluation area of ​​the obtained image information using a control unit, wherein the image evaluation area represents a corresponding field evaluation area of ​​the captured field section with a depth T(evaluate) in the direction of travel of the spraying device; and applying the spray agent to the field evaluation area of ​​the captured field section depending on the plants identified in the image evaluation area using the spray nozzle unit of the agricultural spraying device. the following further step is planned: Selecting a variable depth T(evaluation) of the image evaluation area using the control unit.

[0008] The present invention further relates to a control unit which is configured to perform and / or control the following steps: Identifying plants in an image evaluation area of ​​received image information of a captured field section of an agricultural area with a depth T(image) in the direction of travel of a spraying device, wherein the image evaluation area represents a corresponding field evaluation area of ​​the captured field section with a depth T(evaluate) in the direction of travel of the spraying device; outputting a control signal to at least one spray nozzle unit of an agricultural spraying device depending on the plants identified in the image evaluation area in order to apply the spraying agent to the field evaluation area of ​​the captured field section. the control unit is further configured to perform and / or control the following additional step: Selecting a variable depth T(evaluation) of the image evaluation area, especially depending on the speed of the agricultural spraying device in the direction of travel.

[0009] The present invention further relates to an agricultural spraying device for applying a spraying agent to an agricultural area, comprising at least one spray nozzle unit, at least one optical detection unit, in particular wherein an optical axis of the optical detection unit has an inclination angle greater than 0° relative to the vertical in the direction of travel of the spraying device, and a control unit as described above.

[0010] Finally, the present invention relates to a computer program configured to execute and / or control the steps of a previously described method and / or control unit when the computer program is executed on a computer, and to a machine-readable storage medium containing the computer program stored thereon.

[0011] The method is intended for agricultural purposes, but is not limited to them. Within the scope of the present invention, an agricultural purpose can be understood as a purpose aimed at the economic cultivation of crops.

[0012] The application of the herbicide takes place on agricultural land or land used for agriculture. This can refer to a field or cultivated area, or even a section of such land. The agricultural land can therefore be arable land, grassland, or pasture. The plants can include, for example, crops whose fruit is used for agricultural purposes (e.g., as food, animal feed, or energy crops), as well as weeds, unwanted plants, and grasses.

[0013] Preferably, all steps of the process are carried out during movement, in particular during travel or flight, of the agricultural spraying device over the agricultural area. Therefore, depending on the design of the spraying device, the term "direction of travel" in the present application can also be understood as a "direction of flight".

[0014] Advantageously, the agricultural spraying device is designed to carry out the process automatically and / or autonomously in order to enable fast, reliable and efficient treatment of a field.

[0015] The agricultural spraying device can, in particular, be part of an agricultural field sprayer or plant protection equipment, or be designed as an agricultural field sprayer or plant protection equipment. The agricultural spraying device can comprise a mobile unit or be mounted on a mobile unit, which can, in particular, be a land vehicle and / or aircraft and / or trailer. The mobile unit can, in particular, be an agricultural machine, e.g., a tractor, a self-propelled or autonomous field sprayer, or a self-propelled or autonomous robot. The agricultural spraying device can, in particular, be a trailed field sprayer, a self-propelled field sprayer, or a mounted field sprayer. The agricultural spraying device can also be mounted on a hydraulic system of an agricultural machine.It is also conceivable that the agricultural spraying device is mounted on the loading platform of an agricultural machine. Alternatively, the spraying device can be attached to the agricultural machine. The agricultural spraying device, or field sprayer, must have at least one spray tank for holding the spraying agent. The agricultural spraying device, or field sprayer, may also have a mixing unit that directly mixes a spraying agent concentrate with water on the spraying device to create the spraying agent to be applied.

[0016] The spray is, in particular, a spray liquid. The spray may contain or be an agricultural preparation or plant protection product (PPP), especially a plant protection product concentrate. The spray may therefore contain a pesticide, such as a herbicide, fungicide, or insecticide. However, the spray may also contain or be a fertilizer, especially a fertilizer concentrate. In this case, the spray may contain a growth regulator. The spray may contain a granular active ingredient mixed with a carrier liquid. The spray liquid may, for example, be a liquid, suspension, emulsion, solution, or a combination thereof. The spray liquid is preferably in the form of a plant protection product or fertilizer diluted with water. The spray liquid may therefore, for example, be a spray solution.

[0017] The application of the spray agent can be carried out, in particular, by means of a conveying unit. This conveying unit can be designed to convey or direct a liquid and / or granules under pressure, especially for metering. Accordingly, the conveying unit can, for example, comprise one or more pumps, feed pumps, metering pumps, pressure accumulators, screw conveyors, valves, orifices, etc.

[0018] The spray nozzle unit preferably comprises at least one spray nozzle for dispensing the spraying agent and at least one valve for controlling or regulating the amount of spraying agent dispensed. Accordingly, the spray nozzle unit is designed to be controllable or actuated. The valve can be located within or integrated into the spray nozzle. Alternatively, the valve can be positioned upstream of the spray nozzle (in the direction of spraying agent flow). The spray nozzle unit can also comprise multiple spray nozzles, each with its own upstream valve. Furthermore, the spray nozzle unit can comprise multiple spray nozzles with only one upstream valve, so that when the valve is actuated, the spraying agent is dispensed via all spray nozzles of the unit. The valve can be a pulse-width modulated (PWM) valve or a proportional valve.The spray nozzle unit can be configured as a section of a nozzle system within an agricultural sprayer. The spray nozzle units can be controlled individually or separately, in defined groups or combinations, or all together. The spray nozzles within each spray nozzle unit can also be controlled individually or separately, in defined groups or combinations, or all together.

[0019] Each row of field sections (field sections along the direction of movement or travel) can be assigned one or more spray nozzle units or spray nozzles from a spray nozzle unit. For example, each row of field sections can be assigned exactly one spray nozzle unit or spray nozzle from a spray nozzle unit, or exactly two spray nozzle units or spray nozzles from a spray nozzle unit, for treatment purposes.

[0020] The optical detection unit is preferably arranged on the agricultural sprayer. The optical detection unit can comprise at least one multispectral and / or hyperspectral and / or infrared and / or 3D camera. The optical detection unit can be configured to capture or record images in the NIR and / or visual range. The optical detection unit can include a light or illumination unit. The optical detection units can be configured to communicate with each other. Each field section row can be assigned one optical detection unit. However, it is also conceivable that one optical detection unit can detect two or more field section rows. Preferably, an optical axis of the at least one optical detection unit has an inclination angle (a) greater than 0° relative to the vertical in the direction of travel of the sprayer.In other words, the optical detection unit is tilted forward in the direction of travel.

[0021] The spray nozzle unit(s) and the optical detection unit(s) are preferably arranged on a spray boom of the agricultural spraying device.

[0022] The step of capturing the field section can, for example, take place during a pass of the agricultural sprayer with the optical detection unit over the field. Understandably, several field sections can be captured essentially simultaneously by several optical detection units.

[0023] The detected field section can be a detection section or a detected image section of an optical detection unit. Preferably, the detected field section is the entire field section detected within the field of view of the optical detection unit.

[0024] The image information represents the captured field section. The image information is preferably an image or representation of the captured field section. The image information has a depth T(image) in the direction of travel of the spraying device and a width B(image) transverse to the direction of travel of the spraying device.

[0025] The process, or rather the process steps, are understandably repeated. The steps for capturing the field sections are preferably carried out or repeated at a defined time interval, in particular a fixed interval or an interval adapted to the speed of the agricultural spraying device. In other words, the field sections are captured at a defined or speed-dependent frame rate or frame frequency (=refresh rate).

[0026] The plants are identified at least within the image evaluation area. Plants can also be identified across the entire image dataset, for example, when row recognition is required. Identifying plants within the depth-variable image evaluation area of ​​a given image can, for instance, mean determining the presence of plants in the field section or field evaluation area, particularly without classifying individual plants. The plant identification process can include detecting a color component, especially a green component and / or an infrared component, within the field section / field evaluation area or image section / image evaluation area. This can be achieved using the optical detection unit, for example.Plants are detected using a predetermined NDVI value (Normalized Differenced Vegetation Index, which is formed from reflectance values ​​in the near-infrared and visible red wavelength range of the light spectrum) by differentiating biomass or vital plants and plant parts from the soil.

[0027] The image evaluation area is the portion of the image information in which plants are identified and which is evaluated, for example, to determine a plant identification number using the control unit. The image evaluation area thus represents a corresponding field evaluation area of ​​the recorded field section. The image evaluation area has a depth T(evaluate) in the direction of travel of the spraying device and a width B(evaluate) perpendicular to the direction of travel of the spraying device. The depth T(evaluate) of the image evaluation area is generally smaller than the depth T(image) of the image information, but can also be the same. Preferably, the image evaluation area has a minimum depth T(evaluate,min) of 20% and / or a maximum depth T(evaluate,max) of 100% of the depth T(image) of the image information. The width B(evaluate) of the image evaluation area can be smaller than the width B(image) of the image information.

[0028] It should be noted that the image information can include further separate image evaluation areas without departing from the scope of the present invention. The number of image evaluation areas per image depends on the spray nozzle spacing and the width of the image information. Each image evaluation area can be assigned to a spray nozzle unit with one or more spray nozzles. For example, with an image information width of 1.5 m and a spray nozzle spacing of 25 cm, 6 image evaluation areas per camera would be provided.

[0029] In the application step, if a positive "spraying decision" is made, the pesticide is applied to the field evaluation area of ​​the recorded field section, depending on the plants identified in the image evaluation area or the determined plant identification number, using the spray nozzle unit of the agricultural spraying device, preferably with a defined minimum quantity per area. The pesticide is preferably applied to the entire field evaluation area. The field evaluation areas on which pesticide is applied with the defined minimum quantity per area are subsequently also referred to as sprayed or treated field evaluation areas.

[0030] Preferably, a step of determining a plant identifier for the image evaluation area using the identified plants in the image evaluation area by means of the control unit is provided, wherein in the application step the spray agent is applied to the field evaluation area depending on the determined plant identifier, in particular when a defined threshold value for the plant identifier is reached and / or undershot and / or exceeded.

[0031] The plant identification number represents, or preferably is, the degree of plant cover of the corresponding field evaluation area and / or the quantity of plant material in the respective field evaluation area and / or the number of identified plants in the respective field evaluation area. The degree of cover can be defined by the ratio of the area covered by plant material to the total area to be evaluated. The degree of cover for the field evaluation area is therefore the ratio of the area of ​​the vegetated area to the respective total image evaluation area. For this purpose, the number of pixels in the respective image evaluation area at which plant material is detected can be determined. Thus, a measure of infestation can be derived from the plant identification number, based on which a decision is made as to whether and, if so, how (e.g., with what application rate) the corresponding field evaluation area is sprayed or treated.

[0032] The threshold can be manually entered, a previously defined value transferred to the system, or a preset value permanently configured within the system. Depending on the crop in the field, the growth stage, and the spray or plant protection product used, a so-called spraying rule can be defined, i.e., a relationship between a specific plant indicator and the decision of whether and how much plant protection product should be applied. For example, the rule could be: "If the coverage in the plant evaluation area exceeds 0.5%, then application will be made to the field evaluation area."

[0033] Preferably, a step of identifying plant rows within the image evaluation area and / or the image information can be provided using the control unit, with the spray agent being applied in the application step depending on the identified plant rows. The plant row identification step can be performed continuously. The plant row identification step is preferably carried out using and / or evaluating all or substantially all of the image information received, i.e., over the entire depth T(image).

[0034] Advantageously, plant rows can be identified using at least one of the following pieces of information: color proportion, especially the green component, of the recorded plants; infrared component of the recorded plants; plant spacing; row spacing; plant growth stage; and geocoordinates of a planting location. Using this information or these properties, plant rows can be identified simply and reliably. Since plant rows generally extend in straight lines, identification can also be achieved, for example, by fitting a straight line or a straight line representing the center point of the plant row into an image trajectory with the highest green component or green value. In the identification step, all plant rows in the recorded field section are preferably identified.

[0035] The control unit can comprise a processing unit or a plurality of processing units for processing signals or data, at least one storage unit for storing signals or data, and at least one communication interface for reading data, in particular for receiving image information, and for outputting data, in particular control signals, to a unit, especially an actuator. Each optical detection unit can be assigned a processing unit, or each optical detection unit can have its own processing unit. The processing unit(s) is / are designed or configured for image processing so that it can perform calculation or image processing steps to carry out the method according to the invention. Accordingly, each processing unit has corresponding image processing software.The processing unit can be, for example, a signal processor, a microcontroller, or the like, while the storage unit can be flash memory, an EPROM, or a magnetic storage device. The communication interface can be configured to read or output data wirelessly and / or via wired connections, whereby a communication interface capable of reading or outputting wired data can, for example, read this data electrically or optically from or output it into a corresponding data transmission line.

[0036] Accordingly, the method according to the invention can be implemented, for example, in software or hardware or in a mixed form of software and hardware in the control unit or a control device.

[0037] The control unit can be fully or partially located on or integrated into the agricultural sprayer. Alternatively, the control unit can also be fully or partially integrated externally, for example, in a cloud.

[0038] According to the invention, the depth T(evaluation) of the image evaluation area can be variably selected or adjusted by means of the control unit. In other words, the image evaluation area is depth-variable. Within the scope of this application, "variable selection" of a depth is understood to mean selecting or setting a value for the depth. Advantageously, the depth T(evaluation) of the image evaluation area is selected by the control unit as a function of the speed of the agricultural sprayer in the direction of travel. In other words, the depth T(evaluation) is also increased with increasing travel speed. Alternatively or additionally, the depth T(evaluation) of the image evaluation area is preferably selected by the control unit as a function of the frame rate of the field sections captured and / or a temperature of the control unit.

[0039] The selection of the depth T(evaluations) can either be done within a downstream image processing software of the computing unit or, if supported by the optical acquisition unit or camera, directly as a ROI definition (region of interest) at the level of the imager chip of the optical acquisition unit or camera.

[0040] As explained in the introduction, maintaining a (predefined) "overlap" of the image evaluation areas requires increasing the frame rate, for example, when increasing the driving speed. However, increasing the frame rate massively increases the number of computational operations, since most operations are applied to the entire image, which in turn leads to an undesirable increase in energy consumption and the associated thermal load. The method according to the invention now makes it possible to keep the frame rate constant or even reduce it by adjusting the depth T(evaluations), thereby keeping energy consumption and thermal load essentially constant or reducing them. Thus, for example, at increased speed, the depth T(evaluations) of the image evaluation area can be increased or extended to maintain the overlap without changing the frame rate.

[0041] It is advantageous if a rear edge of the image evaluation area, in the direction of travel of the agricultural sprayer, aligns with a rear edge of the image information, also in the direction of travel of the agricultural sprayer. In other words, the edges overlap. This results in a maximum selectable depth range for T(evaluation), i.e., a maximum depth T(evaluation,max).

[0042] Alternatively, it is advantageous if the rear edge of the image evaluation area, in the direction of travel of the agricultural sprayer, is selected by the control unit depending on the speed of the agricultural sprayer in the direction of travel. This measure allows the reaction distance, i.e., the distance between the image evaluation area and the spray nozzle unit, to be increased, thus enabling a further increase in the maximum driving speed. Drawings

[0043] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of an agricultural spraying device according to the invention; Fig. 2 a schematic representation of a basic geometric arrangement of optical detection unit and spray nozzle unit relative to each other; Fig. 3 a schematic representation of obtained image information with a depth-variable image evaluation section; and Fig. 4 a flowchart of a method according to an exemplary embodiment.

[0044] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and acting similarly, without repeating the description of the elements.

[0045] In Fig. 1 Figure 1 is a schematic representation of an agricultural spraying device, which in its entirety is marked with the reference numeral 10.

[0046] The agricultural spraying device 10 is designed as a field sprayer 10. The field sprayer 10 is arranged on a mobile land vehicle 12, which is designed as a tractor 12.

[0047] The agricultural spraying device 10 has a spray boom 14. Spray nozzle units 16 and optical detection units 18 are arranged on the spray boom 14. The spray nozzle units 16 are designed to apply a spraying agent 20 to plants 22 or weeds 22 of an agricultural area 24. The optical detection units 18 are designed as optical cameras 18. The optical cameras 18 each include a filter unit to extract a color component, such as the green component, from a received or captured image in order to detect plants 22 or weeds 22.

[0048] The agricultural spraying device 10 also has a (not shown) conveying unit by means of which the application rate or an active ingredient quantity in the spraying agent 20 to be applied can be adjusted or varied.

[0049] The agricultural spraying device 10 also includes a control unit 26, which is connected to the optical cameras 18 in order to receive information from them. The control unit 26 includes a processing unit 28, which is configured to perform calculation steps or image processing steps for carrying out the method according to the invention. The control unit 26 is further configured to output a control signal such that the spraying agent 20 is applied by means of the spray nozzle units 16, depending on the determined plant identification number.

[0050] Fig. 2 Figure 1 shows a basic geometric arrangement of a spray nozzle unit 16, which, in the case of a positive spraying decision, applies the spraying agent 20 to a spraying area 29, and an inclined optical detection unit 18 or camera 18 on the agricultural spraying device 10. The angle of inclination a is the angle in the direction of travel 30 of the spraying device 10 between an optical axis 32 of the camera 18 and a vertical 34.

[0051] As from Fig. 2 and 3As can be seen, a field section 36 of the agricultural area 24 is captured by means of the optical detection unit 18 in order to obtain image information 38 of the field section 36 with a depth T(image) 39 in the direction of travel 30. Subsequently, the plants 22 are identified in an image evaluation area 40 of the obtained image information 38, wherein the image evaluation area 40 represents a corresponding field evaluation area 42 of the captured field section 36 with a depth T(evaluation) 43 in the direction of travel 30 of the spraying device 10. According to the invention, the depth T(evaluation) 43 of the image evaluation area 40 is variable and is selected or adjusted by means of the control unit 26 depending on the travel speed of the spraying device 10. In this process, a rear edge 44 of the depth-variable image evaluation area 40 in the direction of travel 30 aligns with a rear edge 46 of the image information 38.Depending on the plants 22 identified in the image evaluation area 40, the spray agent 20 is then applied over a wide area to the field evaluation area 42 of the recorded field section 38 using the spray nozzle unit 16.

[0052] Fig. 4Figure 1 shows a flowchart of a process 100 for applying a pesticide 20 to an agricultural area 24 using at least one spray nozzle unit 16 of an agricultural spraying device 10. The process comprises a step of sensing 102 a field section 36 of the agricultural area 24 using at least one optical sensing unit 18 in order to obtain image information 38 of the field section 36 at a depth T(image) 39 in the direction of travel 30 of the spraying device 10. The process 100 further comprises a step of selecting 104 a variable depth T(evaluation) 43 of the image evaluation area 40 using the control unit 26.Method 100 further comprises a step of identifying 106 plants 22 in the image evaluation area 40 of the received image information 38 by means of the control unit 26, wherein the image evaluation area 40 represents a corresponding field evaluation area 42 of the recorded field section 36 with a depth T(evaluation) 43 in the direction of travel 30 of the spraying device 10. Method 100 further comprises a step of applying 112 the spray agent 20 to the field evaluation area 42 of the recorded field section 36 depending on the plants 22 identified in the image evaluation area 40 by means of the spray nozzle unit 16 of the agricultural spraying device 10.

[0053] Method 100 further comprises an optional step of determining 108 a plant identification number for the depth-variable image evaluation area 40 using the identified plants 22 in the depth-variable image evaluation area 40 by means of the control unit, wherein in the application step 112 the spray agent 20 is applied to the field evaluation area 42 depending on the determined plant identification number, in particular when a defined threshold value for the plant identification number is reached and / or fallen below and / or exceeded. Alternatively or additionally, Method 100 comprises an optional step of identifying 110 plant rows in the depth-variable image evaluation area 40 and / or the image information 38 using the identified plants 22 by means of the control unit 26, wherein in the application step 112 the spray agent 20 is further applied depending on the identified plant rows.

[0054] If an embodiment includes an "and / or" connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

1. Method (100) for applying a spray (20) to an agricultural area (24) by means of at least one spray nozzle unit (16) of an agricultural spraying device (10), having the steps of: - capturing (102) a field section (36) of the agricultural area (24) by means of at least one optical capture unit (18) in order to obtain image information (38) from the field section (36) with a depth T(image) (39) in the direction of travel (30) of the spraying device (10); - identifying (106) plants (22) in an image evaluation area (40) of the obtained image information (38) by means of a control unit (26), wherein the image evaluation area (40) represents a corresponding field evaluation area (42) of the captured field section (36) with a depth T(evaluate) (43) in the direction of travel (30) of the spraying device (10); and - applying (112) the spray (20) to the field evaluation area (42) of the captured field section (36) by means of the spray nozzle unit (16) of the agricultural spraying device (10) on the basis of the plants (22) identified in the image evaluation area (40) , characterized by the further step of: - selecting (104) a variable depth T(evaluate) (43) of the image evaluation area (40) by means of the control unit (26).

2. Method (100) according to Claim 1, characterized in that the depth T(evaluate) (43) of the variable-depth image evaluation area (40) is selected by means of the control unit (26) depending on a speed of the agricultural spraying device (10) in the direction of travel (30) .

3. Method (100) according to Claim 1 or 2, characterized in that the depth T(evaluate) (43) of the variable-depth image evaluation area (40) is selected by means of the control unit (26) depending on an image rate of captured field sections (36) and / or a variable related to a temperature of the control unit (26).

4. Method (100) according to any one of the preceding claims, characterized in that a rear edge (44) of the variable-depth image evaluation area (40) in the direction of travel (30) of the agricultural spraying device (10) is aligned with a rear edge (46) of the image information (38) in the direction of travel (30) of the agricultural spraying device (10).

5. Method (100) according to any one of Claims 1 to 3, characterized in that a rear edge (44) of the variable-depth image evaluation area (40) in the direction of travel (30) of the agricultural spraying device (10) is selected by means of the control unit (26) depending on a speed of the agricultural spraying device (10) in the direction of travel (30).

6. Method (100) according to any one of the preceding claims, characterized in that the variable-depth image evaluation area (40) has a minimum depth T(evaluate,min) of 20% and / or a maximum depth T(evaluate,max) of 100% of the depth T(image) (39) of the image information.

7. Method (100) according to any one of the preceding claims, characterized in that a width B(evaluate) of the variable-depth image evaluation area (40) is smaller than a width B(image) of the image information.

8. Method (100) according to any one of the preceding claims, characterized in that the field section (36) is captured with an angle of inclination (a) of an optical axis (32) of the optical capture unit (18) of greater than 0° relative to the vertical (34) in the direction of travel (34) of the spraying device (10).

9. Method (100) according to any one of the preceding claims, characterized by a step of determining (108) a plant metric for the variable-depth image evaluation area (40) using the identified plants (22) in the variable-depth image evaluation area (40) by means of the control unit, wherein, in the step of application (112), the spray (20) is applied to the field evaluation area (42) depending on the determined plant metric, in particular upon reaching and / or falling below and / or exceeding a defined threshold value for the plant metric.

10. Method (100) according to Claim 9, characterized in that the plant metric represents a degree of coverage of the field evaluation area (42) with plant material and / or an amount of plant material in the respective field evaluation area (42) and / or a number of identified plants (22) in the field evaluation area (42).

11. Method (100) according to any one of the preceding claims, characterized by a step of identifying (110) rows of plants in the variable-depth image evaluation area (40) and / or the image information (38) by means of the control unit (26) by using the identified plants (22) in the entirety of the image information (38), the step of application (112) involving the spray (20) further being applied on the basis of identified rows of plants.

12. Control unit (26) configured to perform and / or control the following steps: - identifying (106) plants (22) in an image evaluation area (40) of obtained image information (38) relating to a captured field section (36) of an agricultural area (24) having a depth T(image) (39) in the direction of travel (30) of a spraying device (10), wherein the image evaluation area (40) represents a corresponding field evaluation area (42) of the captured field section (36) with a depth T(evaluate) (43) in the direction of travel (30) of the spraying device (10); - outputting a control signal to at least one spray nozzle unit (16) of an agricultural spraying device (10) depending on the plants (22) identified in the image evaluation area (40) in order to apply the spray (20) to the field evaluation area (42) of the captured field section (36), characterized in that the control unit (26) is also configured to perform and / or control the following further step: - selecting (104) a variable depth T(evaluate) (43) of the image evaluation area (40), in particular depending on the speed of the agricultural spraying device (10) in the direction of travel (30).

13. Agricultural spraying device (10) for applying a spray (20) to an agricultural area (24) using at least one spray nozzle unit (16), at least one optical capture unit (18), in particular wherein an optical axis (36) of the optical capture unit (18) has an angle of inclination (a) greater than 0° relative to the vertical (38) in the direction of travel (34) of the spraying device (10), and a control unit (26) according to Claim 12.

14. Computer program configured to execute and / or to control the steps of a method according to any one of Claims 1 to 11 and / or a control unit (26) according to Claim 12 when the computer program is executed on a computer.

15. Machine-readable storage medium with the computer program according to Claim 14 stored thereon.