When the VRA map is complete, the next step is to build control strips. Control strips are special areas in productivity zones where a trial is set up to compare application rates. Control strips are necessary to interpret the results of the trial, i.e., how different application rates affected yield in different zones.
The app creates control strips automatically, so you don't have to build them manually. That said, you should still set up a few things and make sure to follow the platform's recommendations.
How to build control strips:
Choose the number of control strips
There are two options:
1 control strip with the farm’s standard rate in high- and low-productivity/NDVI zones.
2 control strips in each zone:
Use the standard and low rates in the high-productivity/NDVI zone.
Use the high and low rates in the medium-productivity/NDVI zone.
Use the standard and low rates in the low-productivity/NDVI zone.
Our recommendation is to use 2 control strips because it's better when all three rates are applied to all management zones. In this case, we can evaluate how effective variable-rate application was in all the zones and determine the best rate for each of them. When we use one control strip, we can only evaluate if VRA was effective or not in the high- and low-productivity/NDVI zones.
Specify the machinery's direction
This is the direction that seeding or harvesting is done. Try to specify it as accurately as possible because the accuracy of the trial results depends on it.
Select the direction of the control strips
By default, control strips are oriented perpendicular to the machinery's direction. This way, it's easier to analyze the trial results. Keep in mind, though, that the control strips must be at least 70 meters wide. This is because the machinery switches the application or seeding rates after a delay. If you're sure that your machinery immediately switches rates, you can decrease the control strip's width.
You can also build control strips parallel to the machinery's direction as long as the harvest within and around the control strip's boundaries is done at the same time using the same combine. If the field is harvested by several combines, the trial results will be difficult to analyze because of the difference in their calibration. Please make sure that combines are properly calibrated before harvesting a field in which you set up a trial.
If you want to use AB lines from the John Deere Operations Center to build control strips, you can see how to do it in this section.
Set the control strips' width
The app will automatically set it to 100 meters. You can decrease the width if you're sure your machinery immediately switches rates.
When building control strips, our algorithm factors in certain rules.
If you selected the perpendicular orinentation: The control strip boundaries that are oriented perpendicular to the machinery direction should lie in one management zone, and each of these boundaries should lie in the most homogenous area in terms of productivity potential/NDVI values.
If you selected the parallel orinentation: The control strip boundaries that are oriented paralel to the machinery direction should lie in one management zone, and each of these boundaries should lie in the most homogenous area in terms of productivity potential/NDVI values.
You may notice that the actual width of the control strip may vary by ±10 meters. It depends on how productivity is distributed in the field. Let's say, for example, that you've built control strips that are 90 meters wide. In the high-productivity zone, the width of the control strip can be 100 meters, and in the low-productivity zone, it can be 80 meters. The width of the control strips differs, but you can rest assured that our algorithms have built them in the best places possible and following all the rules.
Now you just need to click 'Export',
select the file format, download it to your computer, and upload it to the machinery.
If you use the John Deere Operations Center, see how to transfer a VRA map to machinery in a few clicks.
Now it's time to go to the field and conduct the operation! After the harvest, upload the yield map to the platform to analyze the results.
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