Contributers:
Dr. Stephen Searcy¹
Dr. George J. Sabbagh²
Jennifer L. Jessip, Research Assistant¹

(1: Agricultural Engr. Dept., Texas A&M University, USA
2: Monsanto, USA)

This study demonstrates and evaluates the creation of management units (MUs) for the purpose of precision farming. The two factors, topography and water infiltration rates, used to delineate MUs were hydrology based. The hydrology model within the spatial analyst extension of ArcView, a GIS, was used to create the subwatershed theme from the topography data and the soil maps from United States Department of Agriculture (USDA) Soil Conservation Service (SCS) were used to create the infiltration rate theme. A hydrologic management unit algorithm (HMUA) was designed to use these two themes as input and create MUs based on a minimum size input from the user. The results were tested separately against MUs based on average slope and infiltration rate. The conclusion was that the MUs generated with the HMUA were more variable across MU boundaries and more homogeneous than that of the two other methods tested.

This script is programmed to let the user input the smallest size management unit that he/she wishes to work with and the script will continue to merge all the small polygons with larger ones until there are no more polygons smaller than what the user specified.

View of a field delineated with ArcView script.