A turbidity module to measure spray mixture concentration for premixing in-line injection system

Authors: ZHANG, ZHIHONG - Kunming University Of Science And Technology; Zhu, Heping; Jeon, Hongyoung; OZKAN, ERDAL - The Ohio State University; WEI, ZHIMING - Shandong Academy Of Agricultural Sciences; SALCEDO, RAMON - The Ohio State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2022
Publication Date: 3/30/2023
Citation: Zhang, Z., Zhu, H., Jeon, H., Ozkan, E., Wei, Z., Salcedo, R. 2023. A turbidity module to measure spray mixture concentration for premixing in-line injection system. Applied Engineering in Agriculture. 39(1):13-21. https://doi.org/10.13031/aea.15245.
DOI: https://doi.org/10.13031/aea.15245

Interpretive Summary: A USDA-ARS developed intelligent spray technology has been commercially available for specialty crop growers to increase precision of pesticide applications and minimize pesticide inputs into the environment. To further improve this new technology, a premixing in-line injection system was developed as an attachment to eliminate tank mixture leftovers. In this research, a portable flow-through turbidity sensor module was developed and tested to measure spray mixture concentrations produced from the premixing in-line injection system. A regression model was established to correlate the sensor output voltage and mixture concentration. The precision and accuracy of the turbidity module was evaluated with different target concentrations and flow rates. An appropriate location for the turbidity sensor to be mounted in the premixing in-line injection system was determined to monitor spray mixture uniformity for variable-rate spray applications. Test results demonstrated the turbidity sensor module was reliable and consistent. The module would have a great potential for real-time monitoring pesticide mixture concentrations produced from the premixing in-line injection system used in variable-rate orchard sprayers or from other tank mixing systems commonly used in conventional sprayers.

Technical Abstract: Monitoring mixture concentrations for precision pesticide spray systems in real time can assure the desired amount of chemicals distributed uniformly to target areas. An in-line turbidity sensor module was investigated to monitor concentrations of spray mixtures produced with a premixing in-line injection system developed for precision variable-rate orchard sprayers. The turbidity sensor was calibrated with simulated pesticides at concentrations ranging from 0% to 30.0%. A cubic polynomial regression model was established for the relationship between sensor output voltages and mixture concentrations. Sensors were mounted at three in-line locations to detect the mixture uniformity differences in the premixing in-line injection system. The module was found to have adequate precision and accuracy to measure concentrations of spray mixtures with simulated pesticides. Relative errors of the sensor were less than 4.70% and the sensor accuracy did not vary with mixture flow rates. Mounting the turbidity sensor downstream of the buffer tank in the premixing in-line injection system would be the optimal location to monitor spray mixture uniformity for variable-rate spray applications. At this location, the relative errors of measured mixture concentrations were between 0.12% and 3.70% which agreed with previous manual measurements. Therefore, there would be a great potential to integrate the in-line turbidity sensor into the variable-rate and even conventional constant-rate sprayers to achieve uniform spray applications in the target field.