Performance of an Aerial Variable Rate Application System with a hydraulically powered chemical pump and boom valve 

by

Lowrey Smith, and S. Thomson

Contact:  Lowrey Smith  email:  lasmith@ars.usda.gov

Summary:

An aerial variable rate application system was evaluated with respect to response to rate change, deposition of spray relative to prescription boundaries, and spray application accuracy.  The variable rate system was composed of a SATLOC-M3 with AirTrack software and a 5 Hz GPS receiver in conjunction with an AUTOCAL II automatic flow controller.  Application rate and ground speed were communicated to the AUTOCAL flow controller by the SATLOC AirTrack so that the prescription application rate could be applied.  Application rates ranging from 0 to 6 gallons per acre (gpa) were assigned to the sub-blocks of the test site and a prescription was prepared for use with the variable rate application system.  Response to rate changes and application accuracy was evaluated from data captured from the automatic flow control system and the placement of spray was evaluated using water sensitive spray cards positioned with respect to zone boundaries and parallel to the flight line.

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