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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/9225

Authors: K. A. Al-Gaadi
Keywords: Sprayer, Site-specific application, Control, Geographical Information System, GIS, Global Positioning System, GPS, Site-specific evaluation, Efficiency
Issue Date: 1999
Abstract: A spatially variable rate herbicide application system was developed and a site-specific evaluation of its field performance and accuracy was conducted. A 4.2-ha (10.4-ac) field was sampled on an 18.3-m (60-ft) grid for soil type and organic matter percent (OM%). A herbicide management table was used to determine the appropriate active ingredient (AI) application rate for each area of the field depending on spatial variation of field parameter data (soil type and OM%). Application rate of AI varied from 3510 mL/ha (1.5 qt/ac) up to 5260 mL/ha (2.25 qt/ac). Using geographical information system (GIS) software, a georeferenced map (management map) of field application rates was produced. A direct nozzle injection field sprayer was equipped with a real-time differentially corrected global positioning system (DGPS). A program was developed to receive on-the-go the sprayer position data (latitude and longitude) and retrieve the desired application rate from the GIS map at the current sprayer field position. A datalogger was used to change on-the-go the AI flow rate (water was used as a substitute for the AI) to correspond with the desired application rate at a specific sprayer ground speed and field position. To evaluate the system accuracy in reproducing the management map, data was collected from the DGPS to determine its field accuracy. DGPS data and datalogger output (data produced by sprayer monitoring sensors) along with the GIS map were utilized to reveal the spatial accuracy of the application system. Control system reaction time and accuracy were investigated using data from the datalogger program output. Results revealed that the DGPS maintained an accuracy of at least 1 m (3.3 ft). Spatial analysis showed that the application system reproduced the application rate management map. On the average, the greatest reaction time of the control system was 2.2 s. For the four application rates used in the study, the highest average application rate error was 2.0%.
URI: http://hdl.handle.net/123456789/9225
Appears in Collections:College of Foods And Agricultural Science

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