Stereo vision controlled variable rate sprayer for specialty crops: Part III. Effect of travel speeds on spray deposition and ground loss

Authors: ROMAN, CARLA - The Ohio State University; Jeon, Hongyoung; Zhu, Heping; OZKAN, ERDAL - The Ohio State University; CAMPOS, JAVIER - The Ohio State University

Submitted to: Journal of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2023
Publication Date: 12/5/2023
Citation: Roman, C., Jeon, H., Zhu, H., Ozkan, E., Campos, J. 2023. Stereo vision controlled variable rate sprayer for specialty crops: Part III. Effect of travel speeds on spray deposition and ground loss. Journal of the ASABE. 66(6):1469-1479. https://doi.org/10.13031/ja.15699.
DOI: https://doi.org/10.13031/ja.15699

Interpretive Summary: Protecting specialty crops from pests and diseases is required to provide high quality crops and yields. Applying crop protection products (CPP) at a uniform rate is essential for pest control. However, specialty crops increase in size and canopy volume throughout the growing season, thus a single application rate would create over- and under-applications throughout the season depending on application timing. Limited technologies are available to minimize non-uniform applications. A prototype variable-rate sprayer coupled with a stereo vision system was developed and tested in an apple tree orchard to match spray outputs to crop size. The performance of the sprayer was evaluated against a conventional sprayer in terms of spray volume reduction, spray deposit and coverage uniformity, and ground losses under typical travel speeds for specialty crop applications. The results showed that the stereo vision-guided variable rate sprayer had more uniform deposition and coverage, used less spray volumes, and had less ground losses compared to the conventional sprayer. The outcomes from this research can be used in the specialty crop production and would reduce CPP use for US growers and minimize adverse effects to the environment from CPP applications.

Technical Abstract: A prototype of novel stereo vision controlled real-time variable rate sprayer was evaluated in an apple orchard in order to mitigate the risks derived from the use of crop protection products applied at a conventional constant rate in specialty crops. The effects of travel speed (from 3.2 to 8.0 km h-1) on spray volume reduction, canopy deposition and coverage, and ground loss were assessed. Test results demonstrated that the travel speed did not influence spray deposition, coverage, or ground losses. The variable rate sprayer reduced the spray volume by more than 44% for the canopy volumes detected in the orchard (<2.2 m3) in comparison to the constant rate spray application. Overall spray volume reductions were 79.1%, 73.8%, 71.0%, and 69.8% when the sprayer traveled at 3.2, 4.8, 6.4, and 8.0 km h-1, respectively, compared to the constant rate applications at a travel speed of 8.0 km h-1. In addition, the variable rate application of the sprayer increased the crop interception, a ratio of a spray deposition to a spray volume, by 16.1% compared to the constant rate spray application when traveling at 8 km h-1. Moreover, the sprayer reduced total ground loss by 57.6% compared to the constant rate application which would minimize adverse impacts of pesticide applications to non-target organisms and unnecessary pesticide losses to the environment. The results of this study suggest that the prototype sprayer has significant potential as a cost-effective solution for sustainable specialty crop spray applications.