Creating variable rate prescription map for Fertilizing based on Relative biomass - drone imagery

This guide explains how to create a fertilization prescription map based on relative biomass in the CultiWise application. It outlines the steps to initiate, configure, and download the prescription map. 

By assigning different fertilizer rates to specific field zones using relative biomass data from drone imagery, this approach optimizes nutrient distribution, increases efficiency, and enhances overall crop performance.

Generating zones

Input layer 

• All vegetation indices derived from drone imagery are available for selection. In most cases, NDVI provides the best representation of vegetation differences across the field.

Opacity 

• Adjust the opacity to reveal underlying layers such as satellite imagery.

Select gradient map

• Adjust the color scheme to represent index values.

Index histogram 

• The histogram typically has two peaks: the first representing soil (lower vegetation values) and the second representing vegetation. Adjust the slider to enhance differences.

Note: Adjusting opacity, gradient, or the histogram slider does not affect the actual variable rate map; it only changes the display settings of the selected vegetation index.

Zone count

• You can define 2 to 10 zones. 
• Fields with greater vegetation variability may benefit from a higher zone count.

Smoothing

• Higher smoothing levels eliminate small areas and create smoother zone boundaries. 
• While this can help prevent issues with sprayer accuracy on complex maps, excessive smoothing may result in a loss of detail.

Example: Smoothing 1

Example: Smoothing 5

Resolution

• A higher resolution (smaller number) generates a more detailed map, capturing smaller vegetation differences such as minor damaged areas.

Note: Experiment with different smoothing and resolution settings to find the optimal balance between simplicity and effective zone separation.

Note: Generated zones remain as temporary layers until saved as a prescription map. Adjust zone count, smoothing, or resolution if the results do not meet your requirements.

Rate settings

To apply the desired product amount across field zones, start by entering data and setting up an automatic distribution strategy. After the calculation, if you're not satisfied with the result, you can reenter the inputs or manually adjust the rates.

Rate unit 

• Select the appropriate unit based on the applied product. The Standard Rate represents the rate typically used for a broadcast application.

Strategy 

• Choose whether to apply a higher dose to: Strong zones (denser vegetation) or Weak zones (less developed vegetation).

Decrease in weakest zone 

• Define the percentage decrease in application rate for the weakest zone compared to the standard rate.

Increase in strongest zone 

• Define the percentage increase in application rate for the strongest zone compared to the standard rate.

Rates for each zone can be adjusted manually. Volume savings are calculated based on the standard rate, which can be modified above the chart for calculation purposes only.

Rates can be adjusted using two strategies:

• Force Edit Total Amount - Adjusts all rates proportionally to match a predefined total product amount.
• Force Edit Average Rate - Adjusts rates to maintain a specified average application rate per hectare.

At the end, you can rename the map (layer name) and select the correct machine type.

Note: Most sprayers and terminals support the generic VRA map format.

Generated map will be available under the dataset from which it was created. It can be exported for use with compatible machinery and software.

• To export the prescription map, click 'EXPORT AS .SHP' below the map legend.
• This will generate a shapefile compatible with agricultural machinery and software.