Development and evaluation of an optical sensing system for detection of herbicide spray droplets

Authors: Huang, Yanbo; MA, WEI - Chinese Academy Of Agricultural Sciences; Fisher, Daniel

Submitted to: Advances in Internet of Things
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2021
Publication Date: 1/21/2021
Citation: Huang, Y., Ma, W., Fisher, D.K. 2021. Development and evaluation of an optical sensing system for detection of herbicide spray droplets. Advances in Internet of Things. 11:1-9. https://doi.org/10.4236/ait.2021.111001.
DOI: https://doi.org/10.4236/ait.2021.111001

Interpretive Summary: Monitoring of herbicide spray droplet drift is important for crop production management and environment protection. Existing spray droplet drift detection methods are time-consuming, laborious, and biased with additives to indirectly trace the sprayed content. Scientists from USDA ARS Crop Production Systems Research Unit and Sustainable Water Management Research Unit at Stoneville, Mississippi and Chinese Academy of Agricultural Sciences, Chengdu, Sichuan, China have collaboratively developed a new spray droplet detection system directly based on analysis of optical spectrum over the droplets. The results indicated that the system can be used to detect the sprayed droplets with high accuracy and the droplets spread over small, medium and large sizes typically used in crop protection. This study provides a new method with a system prototype for effective detection of spray droplet drift in crop production.

Technical Abstract: Real time monitoring of herbicide spray droplet drift is important for crop production management and environment protection. Existing spray droplet drift detection methods, such as water sensitive paper and tracers of fluorescence and Rubidium chloride, are time-consuming and laborious, and the accuracies are not high in general. Also, the methods of tracer indirectly quantify the spray deposition from the concentration of the tracer and may change the drift characteristics of the sprayed herbicides. In this study, a new optical sensor system was developed to directly detect the spray droplets without the need to add any tracer in the spray liquid. The system was prototyped using a single broadband programmable LED light source and a near infrared sensor containing 6 broadband spectral detectors at 610, 680, 730, 760, 810, 860 nm to build a detection system prototype potentially for monitoring and analysis of herbicide spray droplet drift. A rotatory structure driven by a stepper motor in the system was created to shift the droplet capture fishing line going under the optical sensor to measure and collect the spectral signals that reflect spray drift droplets along the line. The system prototype was tested to be able to detect small (Very Fine and Fine), medium (Medium) and large (Coarse) droplets within the droplet classifications of American Society of Agricultural and Biological Engineers. The testing results indicated that the system could detect the droplets of different sizes and determine the droplet positions on the droplet capture line with 100% accuracy at the wavelength of 610 nm selected from the 6 bands to detect the droplets.