Creating Variable N-Rate Application maps for multiple fields of the same crop type at once is possible in the Atfarm web app in your desktop browser. The application maps are auto-generated using the VRA algorithms.

Please note before you start:

• Read here about the equipment required, file types by terminal and how to request a test file.
• The maximum field size for creating application maps is 1,500 ha. The minimum field size is 1 ha with a minimum field width and length of 50 m. Read here about the field sizes.
• To create an accurate application map, ensure that non-crop areas are excluded when adding your fields to Atfarm. When you draw the field, you can add inner boundaries and adjust the outer field boundary.
• We don't currently take fertiliser restrictions into account when creating application maps. When fertilising your crops, please remember to adjust the fertiliser application to comply with government fertiliser restrictions.
• Grassland: You can create application maps for mown grass (not grazed grass) consisting mainly of ryegrass (Lolium sp.), fescue (Festuca sp.) and timothy (Phleum sp.) with no more than 5 % clover in the sward. However, we're already working on calibrating the algorithm for grass with higher clover content.

1) Select your fields

Initiate the batch map creation as follows:

1. Log in to Atfarm from your desktop browser.
2. Select the desired farm in the farm overview.
3. Click + Multiple VRAs in the field overview.
4. Tick the box next to a field to select it for the batch map creation.
   • Creating multiple application maps at once is only possible for fields of the same crop type.
5. Click Continue to proceed to the VRA Map Builder.

2) Define global parameters

You're now in the 1st step of the VRA Map Builder, where you define the global parameters that will be used in all application maps. You'll be able to adjust these parameters for each field in the next step.

Proceed as follows:

1. Depending on the crop type, select the growth stage of your crop for the biomass map date from the dropdown.
   • The VRA N-Sensor algorithm is based on thousands of samples and lab tests and adapts to the crop and growth stage.
   • We recommend a growth stage based on your crop type. As variable rate fertilisation isn't recommended for each growth stage, these can't be selected.
2. Depending on the crop type and growth stage, click on Levelling or Protein dressing to select the variable rate strategy.
   • If you don't see this option, Atfarm has automatically selected the strategy. Read more about the strategies here.
3. Enter the target N rate in kg N/ha in the corresponding input field.
   • The target N rate is the average nitrogen rate to be applied to the field. It's the main input to the VRA N-Sensor algorithm. The satellite images provide information about the different nitrogen uptake in the field, but they don't provide actual absolute nitrogen values. You can use the Yara N-Tester to determine the agronomically optimal nitrogen rate for your next application.
4. Enter lower and upper limit in kg N/ha in the next input fields.
   • The lower and upper limits define the minimum and maximum application rates for the applied variable rate strategy. If the field areas with their calculated application rates are outside these limits, the application rates are adjusted to the set limits. If the calculated application rates are within the limits, the limits aren't applied.
   • For the levelling strategy, the lower limit applies to areas with high biomass/N-uptake and to areas with exceptionally low biomass/N-uptake (<30 % of average field N-uptake).
   • For protein dressing, the lower limit applies to areas of low biomass/N-uptake.
   • The recommended lower limit is 1 kg N/ha. The upper limit should be at least +/- 10 kg N/ha from the target N-rate.
5. Select the fertiliser you want to apply from the dropdown.
   • The fertilisers that can be selected depend on your country. If you don't see your fertiliser in the list, select Other or Generic.
6. If necessary, adjust the % N in the fertiliser in the next input field.
7. Click Save parameters to proceed to the next step.

3) Review and adapt parameters

You're now in the 2nd step of the VRA Map Builder, where you can review and change the parameters of each field.

Proceed as follows:

1. Click Edit in the box of a field to change its parameters and biomass map date.
2. Click on an input field to edit the information.
3. Click on map in the first input field to change the biomass map date to be used to calculate the application map.
4. Select the biomass map date from the timeline below the map that opens.
   • The application maps are created from biomass indexed satellite imagery.
   • Only cloud-free satellite image dates are listed, as biomass indices can only be applied to cloud-free images. However, sometimes dates are marked as cloudy in the timeline when they're actually cloud-free. Read here how to view cloudy satellite images. Once you've found a recent cloud-free image, select it from the timeline to use it for the application map.
   • For best results, use the most recent image as it will reflect the current crop status. The image should be no more than five days old, as older images may show biomass values that don't reflect current conditions. When using old images, make sure they reflect the current crop performance.
5. Click Change map date to save the new date.
6. Once done, click Save to save your edits and go back to the overview.
7. Click Create VRA to generate the application maps.
   • All the application maps created for this farm can be accessed from the VRA overview, which can be accessed from the left hand navigation bar by clicking on VRA. You can also find each field's application map under Recommendations on each field's page.

4) Review and adapt maps

You'll now see an overview of all the application maps created within your farm. For each map you can see the last update date, crop type, target N-rate and fertiliser to be applied.

You can view and adapt the maps as follows:

1. If necessary, click the bin icon in the box of a field to delete its application map.
2. Click the arrow in the box of a field to review its application map.
   
   • The application map consists of a biomass map with the fertilisation pixels as squares or dots depending on the rate adjustment strategy selected. Each colour represents a different nitrogen rate in kg/ha.
   • You can see average N in kg/ha, total N in kg, total fertiliser and the cell size.
   • Each pixel on the map represents the centre of a 20 x 20 m cell. This design allows you to see the biomass through the pixels. The 20 x 20 m pixel resolution is sufficient for current spreader models (most over 20 m spreading width) and can also be used for spreaders with a larger spreading width.
   • Each corner of the field must have a nitrogen value associated with it, even if most of the 20 x 20 m cell is outside the field, so that your terminal can read the application map. You just have to work on the field boundaries as usual. Pixels with areas outside the field boundary are handled by Atfarm's boundary handling algorithm and the application rate is calculated only for the areas of the pixels within the field boundary.
   • The cell size refers to the spatial resolution of the pixels from the satellite data. The scaling of the cells depends on the size of the field. The larger the field, the larger the scale (20 x 20 m, 40 x 40 m, 60 x 60 m, 80 x 80 m, etc.). The larger the scale, the lower the spatial resolution of the pixels from the satellite data.
3. Click Edit next to the fertiliser name to update target N rate, lower and upper limits, fertiliser and % N in fertiliser. When finished, click Update to recalculate the application map.
4. Click on Zone Map or Raster Map to select the rate adjustment strategy.
   • Zone map: Neighbouring pixels with similar N-uptake and corresponding nitrogen levels are grouped into zones. The gradations are created in 10 % steps. This makes it easier to use spreaders which have +/- 10 % buttons. The zone map is best used for manual applications or older terminals. When using the Atfarm mobile app as a terminal and selecting to spread by speed, the zone map is coarser and is therefore recommended as less manual control of the spreader is required.
   • Raster map: The N-uptake and application rate are calculated per pixel and the fertiliser is applied accordingly. The raster map is designed for maximum precision on high-end equipment.
5. Use the brush editor to change the fertilisation zones and amounts.
   • Click on the number below a colour and enter the desired nitrogen rate.
   • Click on a colour to select it, then click on a fertilisation zone on the map to apply the new rate.
   • Use the + and - buttons on the map or your mouse wheel to zoom in and out.
   • Click Undo to undo your last change.
   • Click Reset to clear all changes.
   • To disable the brush, click on the selected colour again.
6. Once you're ready, click Back below the Export button to save your edits and go back to the overview.

5) Export maps

You're ready to export the application maps and transfer them to your terminal.

Proceed as follows:

1. Tick the box next to a field to select its application map for the export.
   
   • To only export a specific application map, click the download icon in the box of the field.
2. Click Export VRAs to go to the export options.
3. Click the download icon next to the desired terminal export option.
   • The file type (ISO-XML, Shapefile) you need to download depends on your terminal. Read here about the equipment required, file types by terminal and how to request a test file.
   • For fields imported from John Deere Operations Center™, you can select the wireless upload option to add and pre-fill a new Work Plan™. Once the map has been uploaded, you'll receive a confirmation and can click View Work Plan to view the plan in John Deere.
   • If desired, select the PDF option to also save the application maps as PDF files. This is ideal for sharing and printing.
4. Click Download in the pop-up.
5. A pop-up will confirm that the export has been successfully initiated.
   • Depending on the number of maps you've selected to export, it may take a while to generate the application files. You can either stay in the app and wait until you receive a pop-up with the download link, or leave the app and check your email inbox for an email from Atfarm after a while. The download link is valid for 48 hours.
6. Click Download generated file in the pop-up in the app. / Click Download in the email.
7. Save the file to the desired location on your computer.
   • Don't rename the folder or the files in the folder. Otherwise, the terminal may not be able to recognise them.
8. Extract the downloaded ZIP folder.
   • Most terminals require unzipped files. A few terminals require zipped files, for example Valtra. In this case, please skip this step.
   • Windows: Right-click the ZIP folder and select Extract All, then click Browse to select the location where you want to extract the folder, and then click Extract.
   • Mac: Double-click the ZIP folder. The newly extracted folder will appear in the same folder.
9. Store the extracted files from the unzipped folder on an empty USB drive.

   • Don't put any files other than the application files on the USB drive. Otherwise, the terminal won't be able to distinguish between the files.

   • You can store application files in Shapefile format for several fields on one USB drive and upload them to your terminal.
   • Don't store application files in ISO-XML format for several fields on one USB drive. Otherwise, the terminal won't be able to distinguish between the files. However, you can store the files on the same USB drive and transfer them one at a time, so that you only need one USB drive. To do this, empty the USB drive before each transfer.
10. Connect the USB drive to your terminal.
11. Load the files from the USB drive.
    • Please refer to your terminal's user manual for instructions on loading the application files onto the terminal.
    • For assistance, please contact your technician, local dealer, manufacturer, or contact our support team. Please let us know what terminal and spreader you're using and provide us with the files you're trying to upload.
12. The zones of the application map will appear on the terminal screen and the application rate will be set.