The application of site-specific agriculture has created a rapid need for technology in the farming community. An area of particular interest is that of utilizing spatially related data to more efficiently apply crop inputs. This has commonly been accomplished through the analysis of field characteristics, the use of variable rate application of farming inputs, and the analysis of yield outputs. Global Positioning Systems have been utilized to provide the real-time location information necessary for correlation of mapping and application systems. The techniques presented in this paper describe the application of navigation systems to agriculture, as navigation overcomes many of the limitations of standard GPS systems. This navigation research has spurred the development of a coupled GPS and INS system designed to advance the state of Site-Specific Agriculture.