How can I use Variable N-Rate Application (VRA) Maps with the Atfarm mobile app?

With our Atfarm mobile app you can variably apply nitrogen, even without having a variable rate controller on your fertiliser spreader. Your smartphone will turn into a terminal.


With our Variable N-Rate Application (VRA) subscription, you can create Variable N-Rate Application (VRA) Maps in the Atfarm web and mobile app. From the Atfarm web app, you can send your created application map to the Atfarm mobile app.


With the Variable N-Rate Application (VRA) Map, you can then create an application task in the Atfarm mobile app.


Depending on the available technology, you can either fertilise by speed adjustment or by spread rate. We use your GPS location to determine the application rate, so that you can manually adjust the flow rate or the travel speed as you drive.


To create an application task with your create application map, proceed as follows:


  1. Open the Atfarm mobile app.
  2. Open your farm and field.
  3. The field view opens. Scroll down and select the desired VRA map. You can also create a VRA map directly in your Atfarm app using the ADD APPLICATION MAP button.
  4. Your generated VRA map will now open. Click on CREATE APPLICATION TASK.
  5. Choose between 'By speed' and 'By flow rate' mode.
  6. Click on START DRIVING.
  7. Activate your location. Make sure to set the GPS accuracy of your mobile device to high. Please consider, that GPS is usually not very accurate in forests and deep valleys.
  8. Mount your smartphone/tablet in your tractor’s cab and set your spreader properly.
  9. Start driving.
  10. After completing the application, click on MARK AS COMPLETE in the Atfarm mobile app.
  11. Click CONFIRM COMPLETION to finish the application task or click CONTINUE DRIVE to resume the application.
  12. You can find the completed application task in your field overview of the field.



'Spread by speed' = Drive mode


If you cannot adjust the flow rate of your fertiliser spreader while driving, you can adjust the driving speed with the drive mode of the Atfarm mobile app.


The app detects which zone of the application map your machine is in and displays the speed to travel at to get the desired result.


After you have followed the steps described above and selected 'By speed' as mode in step 8, please follow these steps:


  1. Enter the preferred average speed under 'Average'.
  2. Set your spreader to the medium flow rate and medium average speed displayed on the screen. 
    In the field, stick to the driving speed displayed in the app.


Please note:

Though the drive mode allows all users easy access to variable fertilisation, there are technical limitations. As you must keep the engine revs constant to ensure an even spread pattern, you need to shift gears to adjust speed. Therefore, the tractor you use should have multiple gears in the speed range on the field. To avoid a drop of speed when shifting gears, it is recommended to use a tractor with a power shift or a CVT /IVT transmission. Using tractors with a low number of gears, or where shifting requires pushing the clutch might lead to off-speed driving and unwanted spreading.



'Spread by flow rate' = Flow rate mode


If your fertiliser spreader has a terminal with manual control system, you can adjust the fertilisation by means of spread rate. The app then shows you how much to manually increase or decrease the spread rate on the spreader terminal based on the application map.


After following the steps above and selecting 'By flow rate' as the mode in step 8, please follow these steps:


  1. Set your spreader to the average flow rate displayed on the screen.
  2. In the field, stick to the flow rate displayed in the app.

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