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How to create a VRA map for planting, fertilization, or applying plant protection products
How to create a VRA map for planting, fertilization, or applying plant protection products
Valeriya avatar
Written by Valeriya
Updated over a week ago

We've set up several thousand VRA trials since 2011. The accumulated experience allowed us to determine our own effective method for conducting experiments and evaluating their effectiveness. We've detailed how the most exciting cases went and their results on our blog.

In this part, we'll discuss how to create VRA maps and set rates for management zones. VRA will help you save on resources and increase yield.


👨‍🌾 How to create a VRA map

🌱 To create a VRA map for planting, do the following:

  1. You can create a map in the 'Prescription maps' section or by clicking the 'Prescription map' button in the field card. Choose the map type: Planting.

  2. Select the type of prescription:

    based on historical productivity zones or on a recent NDVI image. Check out our recommendations about which type to choose in this section.

  3. Select the number of zones.

    Note that it's more convenient to use 3 zones to build control strips. Control strips are necessary to properly interpret the trial results. We'll talk more about them later. If you want to edit the zones, here's how to do that.

  4. In the next window, specify a crop and variety/hybrid.

  5. Input the standard seeding rate and select your preferred unit system (kg/ha or seeds/ha). The seed manufacturer has a standard seeding rate recommendation, but you can also rely on your prior experience.

  6. Specify the rates for each zone.

    If you know how yield varies within this field, follow this rule of thumb: the more heterogeneous the field is, the bigger the gap should be in the low- and high-productivity (or low and high NDVI) zones.

    💡If you don't want to plant a certain zone, input 0 as its rate.

    ​💡 Percentages indicate how much the average productivity value in this zone deviates from the average productivity value in the medium potential zone. The more heterogeneous the field is, the wider the range of application rates should be in the high and low productivity zones.

  7. Enable the 'Trials' section to add control strips to the VRA map.

    Find out more about the control strips and experiments in this article. This step is necessary to analyze and interpret the trial results correctly. If you don't need to do this, you can skip this step and download the VRA map without control strips.

  8. Save the map by clicking the 'Export' button.


If you use the John Deere Operations Center, see how to transfer a VRA map to machinery in a few clicks.

🚜 To create a VRA map for fertilization, do the following:

  1. You can create a map in the 'Prescription maps' section or by clicking the 'Prescription map' button in the field card. Choose the map type: Fertilizer application.

  2. Select the type of prescription:

    based on historical productivity zones or on a recent NDVI image. Check out our recommendations about which type to choose in this section.

  3. Select the number of zones.

    Note that 3 zones are better for building control strips and properly interpreting the results. Control strips are necessary to properly interpret the trial results. We'll talk more about them later. If you want to edit the zones, here's how to do that.

  4. Specify a crop and variety/hybrid.

  5. Input the standard seeding rate and select your preferred unit system (kg/ha or seeds/ha). The manufacturer recommends a standard rate, but you can also go off your prior experience.

  6. Specify the rates for each zone.

    If you know how yield varies within this field, follow this rule of thumb: the more heterogeneous the field is, the bigger the gap should be in the low- and high-productivity (or low and high NDVI) zones.

    💡 If you don't want to apply fertilizer to a certain zone, input 0 as its rate.

    ​💡 Percentages indicate how much the average productivity value in this zone deviates from the average productivity value in the medium potential zone. The more heterogeneous the field is, the wider the range of application rates should be in the high and low productivity zones.

  7. Enable the 'Trials' section to add control strips to the VRA map.

    Find out more about the control strips and experiments in this article. This step is necessary to analyze and interpret the trial results correctly. If you don't want to do this, you can skip this step and download the VRA map without control strips.

  8. Save the map by clicking the 'Export' button.

If you use the John Deere Operations Center, see how to transfer a VRA map to machinery in a few clicks.

🛡 To create a VRA map for plant protection products:

  1. You can create a map in the 'Prescription maps' section or by clicking the 'Prescription map' button in the field card. Choose the map type: Crop protection.

  2. Select the type of prescription:

    based on historical productivity zones or on a recent NDVI image. Check out our recommendations about which type to choose in this section.

  3. Select the number of zones.

    Note that 3 zones are better for building control strips and properly interpreting the results. If you want to edit the zones, here's how to do that.

  4. Specify a crop and variety/hybrid.

  5. Specify the input's type and name, the standard rate, and your preferred unit system. The manufacturer offers a recommended standard rate, but you can also go off your prior experience.

  6. Specify the rates for high- and low-productivity/NDVI zones.

    If you know how yield varies within this field, follow this rule of thumb: the more heterogeneous the field is, the bigger the gap should be in the low- and high-productivity (or low and high NDVI) zones.

    💡 If you don't want to do the application in a certain zone, input 0 as its rate.

    ​💡 Percentages indicate how much the average productivity value in this zone deviates from the average productivity value in the medium potential zone. The more heterogeneous the field is, the wider the range of application rates should be in the high and low productivity zones.

  7. Enable the 'Trials' section to add control strips to the VRA map.

    Find out more about the control strips and experiments in this article. This step is necessary to analyze and interpret the trial results correctly. If you don't want to do this, you can skip this step and download the VRA map without control strips.

  8. Save the map by clicking the 'Export' button.

If you use the John Deere Operations Center, see how to transfer a VRA map to machinery in a few clicks.

💡 Performing multiple operations at once?
Choose the 'Multiple inputs' option and create a VRA map for planting, fertilization or crop protection products application in a single file.

💡 Need to create multiple prescriptions for the same inputs?
Generate maps for multiple fields simultaneously!

Just select the fields you need from the list and click 'Create bulk VRA maps'. In the window that opens, set the required parameters for the entire group of maps at once. Add trials (control strips) for one or several operations, if needed.

💡 Want to navigate maps more effectively?

Assign custom names to VRA maps!

  • On the VRA map creation page

  • In the 'Prescription maps' section

💡 Want to know the area of each zone?

Find out while creating a VRA map! It works for both single and multiple fields.


⚙️ How to set your own thresholds for NDVI-based zones

Thresholds allow you to manually set the min/max NDVI values inside an individual zone. Doing so makes the NDVI prescription map better reflect real field conditions.

Example:

NDVI values on the field vary between 0.6 and 0.72. Our algorithm builds 3 zones of approximately the same size:

  • Zone 1: for parts of the field with an NDVI between 0.6 and 0.64

  • Zone 2: between 0.64 and 0.68

  • Zone 3: between 0.68 and 0.72

You can change the thresholds for each zone, e.g., set Zone 1's threshold values at 0.6-0.66 and specify the application rate for it. If you change thresholds, NDVI zones are rebuilt according to the new rules. After making these changes, the size of the zones won't be equal anymore.

How it works

  1. Start creating a VRA map based on a recent NDVI image.

  2. Select the threshold values for each zone either on the histogram or input them manually for each individual zone. Use the contrasted NDVI layer to identify zones more accurately. If something goes wrong, you can reset the values to their defaults.

  3. Finish building the map the way you usually do, then export the map. Now you're all done!

To simultaneously set threshold values for multiple VRA maps, select various fields from the list and enable uniform threshold values. The NDVI zones for the selected fields will be recalculated as if they were one common field in terms of NDVI values.


🤔 Historical productivity zones or a recent NDVI image?

You can create VRA maps based on historical productivity zones or a current NDVI image. Let's look at which data is better to use for which operation.

You can use current NDVI image in two cases:

1️⃣ To apply nitrogen when vegetation is already present in the field. Here's an example of a successful trial with VRA by NDVI zones. Actually, for in-season nitrogen application, you can also use productivity zones. For example, our trial with the Saturn field would've been more successful if we had used productivity zones to create the maps.

2️⃣ To apply crop protection products.

  • When performing desiccation, more product is applied in the high-NDVI zone and less in the low-NDVI zone. NDVI shows plant health. The healthier the plant is, the more desiccants are needed.

  • When applying growth regulators, more product is used in high-NDVI zones and less in low-NDVI zones. In the high-NDVI zone, the plants are taller and larger, and the ear is heavier. There's a risk of lodging when plants have a heavy ear. Wheat with a heavy ear will produce higher yield, but it's more difficult to harvest.

  • When applying fungicides, more product is applied in high-NDVI zones since fungi and other diseases may develop there because of the higher humidity. In the low-NDVI zones, fewer fungicides are applied.

  • Herbicides are applied to eliminate weeds. At the beginning of the season, you can identify the weed hotspot, which is where you should apply more herbicides based on NDVI data.

🌽🌱🌻 What is the best strategy for different crops?


📝 Editing management zones in VRA maps

The OneSoil Pro platform allows you to edit the boundaries of productivity and NDVI zones in VRA maps. To do this, click the 'Edit zones' button when creating or editing the VRA map. We recommend using this tool only when you know for sure that the zones should be edited this way.

On the left side of the screen are the brush and fill tools. You can select a certain zone color and fill another zone with it. For example, you may want to color your medium productivity zone as a high productivity zone: select the high productivity zone color in the tool panel and click the zone that you want to fill with it.

You can also use the brush to draw zones manually. Select the brush size, choose a zone color you need and adjust your zones by drawing in the map.

If anything goes wrong, you can always undo the changes. All changes can only be made within the boundaries of the field's existing geometry.

On the right side of the screen, you can toggle the layers that you can visualize to help you edit zones: productivity map, soil brightness, elevation, or satellite image.

After the zones are edited, click the 'Save' button. Your zones will appear in the 'Custom' tab of the zone selection panel.


Building a map is the first step in setting up a trial. To find out how different rates affect yield in each productivity zone, we need to build control strips. This will provide you with insights into which zone(s) requires more seeds or fertilizer and which zone(s) can have less.

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