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A variable rate chemical application system was developed to accommodate the spatial variability that occurs in a field. A pressure-based system using a Campbell Scientific, Inc. (CSI) 21X micrologger as the controller and dead reckoning for vehicle location was used. The system was tested using four treatments with five application rate changes per treatment. Three parameters were used to evaluate the system: response distance, percent overshoot, and performance index. The system was found to perform adequately, but could be improved with a more sophisticated control algorithm and more appropriate hardware.