A spatial decision support system for the analysis of environmental impacts of integrated crop-livestock production system

Recent shifts toward intensive and large confined livestock production units to enhance economic growth coupled with increased concerns for air, soil, and water quality have necessitated the development of computer-based management decision support systems for selecting environmentally sound production sites and for planning sustainable production systems. This dissertation describes the development and application of an interactive spatial decision support system that integrates a geographic information system, spatial and biophysical modeling, and a knowledge-based system into an interactive tool to facilitate planning and management of environmentally-sound livestock production. The spatial decision support can be used to select suitable watershed land areas for siting livestock production, to select fields for manure application, and to determine the potential impacts of livestock production practices on ground and surface water quality. The site selection component of the spatial decision support system is based on the ARC/INFO geographic information system and incorporates the effects of land use, soil type, topography, proximity to roads and surface water bodies, and other aesthetic and political considerations as well as multicriteria analysis techniques. The groundwater quality modeling component of the decision support system integrates a geographic information system and water quality modeling, using training sets from NLEAP water quality modeling, to estimate nitrate leaching. In order to evaluate nutrient loading on surface water from integrated crop-livestock production a surface water quality model capable of incorporating the spatial dynamics of watershed was needed. The AGNPS distributed-parameter model was used for this purpose. The AGNPS model integrated with ARC/INFO GIS forms a user-friendly modeling interface for surface water quality analysis. The interface automates extraction of the input parameters from GIS data layers and allows the user to interactively generate scenarios of nutrient management practices in crop-livestock production. In order to demonstrate utility of the integrated system, example applications were performed on 7075-ha Lake Icaria watershed in southern Iowa.