Spatially-variable fertilizer and pesticide application with GPS and DGPS

Abstract Concepts of spatially-variable fertilizer and pesticide application are discussed. Commercial applicators are described which use Global Positioning Systems (GPS) or other location technologies to apply fertilizer and pesticide according to predetermined stepoint maps. The dynamics of the applicator are shown to have important performance effects. Command feedforward control can significantly improve the performance. Further research is needed on understanding the effects of the various error sources.