Variable rate spraying in varied micro-meteorological conditions

Authors

  • L. R. Khot PhD
  • Reza Ehsani Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred, Florida, USA
  • L. G. Albrigo Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred, Florida, USA
  • W. Swen Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred, Florida, USA
  • J. C. Neto Embrapa Agriculture Informatics, Campinas, Sao Paulo, Brazil
  • J. M. Campoy National Robotics Engineering Center, Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
  • C. Wellington National Robotics Engineering Center, Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA

Keywords:

Airblast sprayer, Adjustable air-assistance, Crosswind, Spray coverage, Citrus.

Abstract

This study evaluated effects of crosswind on the variable rate sprayer application treatments spray coverage and deposition on different citrus canopy sizes.  The axial-fan airblast sprayer retrofitted with variable liquid- and air-assist rates was field-tested with different crosswind conditions on small (about 2 m tall and < 1.5 m wide) and medium-sized (about 3 m tall and < 2.5 m wide) canopies.  Crosswinds of 1.3, 2.7, and 4.0 ms-1 on the canopies being sprayed were generated using the stationary conical air shaker as the air blower unit.  Water sensitive papers (WSPs) were used to collect droplet deposits and image processing software was used to analyze the WSPs scanned at 600 dpi.  Percent spray coverage on the WSPs was found to be one of the most suited parameters to evaluate the effectiveness of spray application treatments.  Overall, the variable rate spray application treatments had comparable spray coverage on respective canopies (front, middle, and across WSP locations in the canopy) during all crosswind conditions.  For both types of canopies, spray coverage was higher on the canopy front and decreased as the spray penetrated inside (i.e. canopy middle) and across.  Due to coalescing, larger droplets (Dv,0.5 [volume median diameter] = 838 to 2,624 µm) were formed on the WSPs located on canopy front, whereas coalescing reduced as the spray penetrated inside (Dv,0.5 = 391 to 1,625 µm on canopy middle) and across the canopy (Dv,0.5 = 307 to 508 µm). 

 

Keywords: airblast sprayer, adjustable air-assistance, crosswind, spray coverage, citrus

Author Biography

L. R. Khot, PhD

Postdoctoral Research Associate,ABENCREC, University of Florida

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Published

2014-03-28

Issue

Vol. 16 No. 1 (2014): CIGR Journal

Section

III-Equipment Engineering for Plant Production