Sprayer technology has rapidly advanced in recent years with new rate control systems along with technologies such as guidance and automatic section control.
While these modern technologies can provide substantial benefits for farmers and/or sprayer operators, they do require proper setup, operation, calibration and maintenance.
The primary consideration include selecting the proper nozzles for a specific application, flow meter calibration, and checking nozzle uniformity. These are critical to maximize the benefits of technologies while also maintaining the necessary spray efficacy of products.
During recent on-farm visits, we have found that sprayers are operating outside 10% from the target application rate due to a incorrect flow meter calibration number being set in the controller.This number is something that needs to be routinely checked by the operator especially when changing products.
Sprayer and rate control manufacturers have good, detailed calibration procedures to ensure one establishes the correct calibration number. The easiest method to check is to place a known volume in the tank, spray this volume, and then check and see if the controller indicates the same amount of volume has been applied.
If the applied amounts are not within a few percent, then the flow meter needs to be re-calibrated.
Other procedures exist but consult your operator manual. If you find that this number is inconsistent during your check for a particular product solution, then call your dealer or manufacturer. Incorrect flow meter calibration can lead to unneeded issues!
Another point, based on our farm visits, is that most rate controllers are flow-based systems meaning they control flow but not necessarily pressure. This type of control system needs to be well understood by operators, since pressure in these flow-based systems can vary during field operation.
In this example (RIGHT), the pressure ranged from 5 psi to 65 psi during application in 3 fields. We have had the pressure spikes to over 100 psi at times.
While this pressure fluctuation may not impact some applications, it can for applications where droplet size is critical for product efficacy (e.g. fungicides).
Pressure variations can also impact the risk of drift since these high pressure spikes normally occur when entering and exiting headlands. Again, nozzle selection is important along with sprayer operation to ensure the product is being applied correctly.
For more information, visit www.alabamaprecisionagonline.com or feel free to contact a team member.