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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Publications at this Location » Publication #337949
Title: Determining water sensitive card spread factors for real world tank mixes

Author
item Hoffmann, Wesley
item Fritz, Bradley - Brad
item GIZOTTI-DE-MORAES, JESAELEN - University Of Nebraska
item GUERREIRO DE JESUS, MARCELLA - University Of Nebraska
item KRUGER, GREG - University Of Nebraska

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2018
Publication Date: 3/30/2018
Citation: sHoffmann, W.C., Fritz, B.K., Gizotti-De-Moraes, J., Guerreiro De Jesus, M., Kruger, G. 2018. Determining water sensitive card spread factors for real world tank mixes. Journal of ASTM International. https://doi.org/10.1520/STP160220160019.
DOI: https://doi.org/10.1520/STP160220160019

Interpretive Summary: Users of ground and aerial spray equipment use several measurements to ensure that the products that they are applying are being delivered to the intended target at the desired dosage. These measurements include testing the flowrate of nozzles, adjusting spray angle and nozzle spacing to ensure uniform applications, and measuring the spray droplets at the deposition site for coverage and droplet size. USDA and University of Nebraska-Lincoln researchers developed a new system for measuring the spread of spray droplets from complex tank mixes on water sensitive paper using a controlled-droplet dispenser. This system allowed a more accurate assessment of spray deposition and helps applicators to make more precise spray applications.

Technical Abstract: The use of water sensitive cards provides a quick and easy method to sample the coverage and deposition from spray applications. Typically, this measure is limited to percent coverage as measures of droplet size, and thus deposition rate, are highly influenced by the stain diameter resulting from the droplet deposition and spread on the card. To determine the diameter of the droplets from the resulting stain, spread factor relationships are used. Complicating this process is the fact that the stain diameter, and thus the spread factor, is impacted by the physical properties of the spray solution, meaning different spray solutions require unique spread factor relationships to accurately estimate the droplet size and deposition on water sensitive cards. This study looks at a number of active product tank mixes with a variety of typical adjuvants to determine the unique spread factors for each. Discrete droplets ranging from 200 to 1000 micrometers were generated and deposited on water sensitive cards, after which the resulting stain diameters were compared to the droplet diameters to develop appropriate spread factor relationships.