To improve site-specific management (SSM) for agriculture, there is a need to predict responses to management decisions and provide information regarding individual input variables on a site-specific basis. This can be achieved by linking a crop growth model to a geographical information system (GIS). Additionally, it is important that the GIS interface and model be capable of accommodating actual field measurements to calibrate the model to actual field observations. By allowing midseason adjustments into crop simulations, factors that affect crop growth but are not included in the model that cause the simulation to diverge from actual values can be considered. Linking a crop growth model to a GIS can also be a tool to develop variable-rate prescription application maps that include both the time and amount needed to apply.

The objective of this research was to develop a modified ArcView GIS interface for cotton growth models that incorporated midseason height adjustments and would allow for the generation of variable rate application maps. The cotton model used to develop the interface was GOSSYM, a management -oriented cotton crop simulation model developed by the USDA-ARS-CSRU (Crop Simulation Research Unit) at Mississippi State. It is not intended for this interface to be used solely with a specific crop growth model, but that it be robust enough to be used with a variety of models as they become available with only minor adjustments.