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Best Practices for Drone Chemical Application


The following outlines a workflow for drone chemical application using the DJI Agras T40. This workflow is designed to ensure efficient and effective treatment of crops, from initial planning and estimation to follow-up and evaluation. By following this workflow, users can maximize the benefits of drone technology in agricultural chemical application. This workflow not only guides the process of drone chemical application but also serves as a critical tool in informing our equipment recommendations and selections. By understanding each step of the process, we can identify the specific needs at each stage and recommend equipment that best meets these requirements.

1. Planning and Estimation:

  • Site Walk: Meet the client and conduct a physical survey of the area to understand the terrain, crop, pest, or other issue, and identify any potential obstacles.

  • Mapping Mission: Conduct a mapping mission with a small mapping drone if the flight path is complex, there are obstacles nearby, or the site's satellite imagery is outdated. Conduct a mapping mission with a multispectral imaging drone if the client intends to perform in-depth analysis using multispectral imaging.

  • Evaluation of Current Conditions: Assess the current condition of the crops and pinpoint any areas that require special care. Before spraying, at least one aerial photograph and one photograph from ground level should be taken to compare the site before and after treatment.

  • Developing a Treatment Plan: Select with the farmer the appropriate chemicals for the treatment based on crop type, pest, expert recommendations, and current conditions.

2. Route mission creation

Preferred Method

  • Create boundaries in Pix-4D Fields: Draw boundaries around the fields ot be sprayed in Pix4D fields. Be sure to create holes in those boundaries around obstacles. Pre-planning obstacles into the boundary saves an enormous amount of time in the field. Export those boundaries as a .shp file.

  • Import to the T-40 Remote: Import the.shp file into the DJI Agras T40's remote control. The file should be placed in a folder called "shapefile" inside the "dji" folder on a microSD card. When the user powers on the remote, the interface will prompt them to import the boundary.

  • Create route mission: Open up the boundary on the remote. Click use to start a new route mission. Adjust flight parameters to match the gallons per acre (GPA) requirements of the product. Use route spacing, height above crops, and speed settings to acheive and appropriate swath width.

Other Options

  • Create on Remote: Set up the flight plan on the remote control by drawing a boundary around the intended area. This is available in ROUTE mode on the t40 remote.

  • Fly to Map Points: Use the drone to fly to the edges of the field and mark a point at each location.

  • Fly in Manual+Mode: In M+ mode, the user can manually direct the drone down a course by pointing it in one direction, locking that direction, setting a spray rate, and then moving manually down that direction. This is perfect for small areas where Route Mode can't effectively plan a route or for places where more control is required close to obstacles. The user is not required to plan a boundary in advance.

  • Walk Field and Mark with the Remote: Walk the field and use the remote to mark a boundary.

4. Execution:

  • Setup GCS: Begin by unloading the necessary equipment and establishing a specific landing zone for the drone. Set up a table where log books will be kept for record-keeping purposes. Observe the area to clarify any important information like obstacle heights and locations and weather conditions. Finally, conduct a thorough review of the mission plan, to ensure all steps are clear and understood. Use the below as an SOP

  • Measure Chemical: Check the label rates to ensure the correct amount of chemical is being used. Then, mix the chemical at the strength per acre that the client requested and in accordance with the label.

  • Preflight Check: Follow the manufacturer's standard preflight checks to ensure the drone is ready for operation.

  • Clear Takeoff Area: Make sure the drone's takeoff and landing areas are clear of any obstacles. Ensure that the safe takeoff height and routing connection height are sufficient to avoid obstacles (fences and power lines).

  • Begin Route: Start the drone's flight plan. Continuously monitor the drone and maintain visual line of sight.

  • Re-fill: Refill the drone's chemical supply as needed. Short refill cycles are important to maintain efficiency and effectiveness. The time to fill the tank is usually the primary limiter of efficiency. A high flow transfer pump can help mitigate this.

5. Considerations:

  • Drift Mitigation: Take measures to prevent chemical drift, such as adjusting the spray pattern and height based on wind conditions.

  • Adjuvants: Consider the use of adjuvants to improve the effectiveness of the chemical application. Drift is a primary concern for aerial applications.

  • Sunlight and Dust Disturbances: Be aware of how sunlight and dust can affect the drone's obstacle avoidance. Bright sunlight at a low angle (such as near sunset) can affect the vision system and cause the drone to mistakenly sense an obstacle.

6. Logging:

  • Flight Records: Keep detailed records of each flight, including the date, time, and area covered.

  • Chemical Logs: Record the types and amounts of chemicals used. Each state will have specific requirements for chemical records. The norm is to record the common name, chemical name, caution statement, amount, rate, and restricted entry interval, along with the operator and operator's signature for each job.

  • Flight Path: Use the flight path recording from the drone to show the client exactly where you sprayed.

7. Post-Flight Check:

  • Follow Manufacturer's Standards: Perform a post-flight check according to the manufacturer's guidelines to ensure the drone is in good condition after the mission.

8. Follow-Up and Evaluation:

  • Secondary Mapping Mission, Imagery, Sampling: Conduct a follow-up mapping mission to assess the results of the treatment. Collect imagery and samples as needed for further analysis.

  • Reports: Prepare detailed reports on the mission, including the treatment applied, the results observed, and any recommendations for future treatments.

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