Delineation of management units and integration of crop simulation into a precision farming GIS environment

Abstract

Precision farming is a method used to track field variability in order to optimize site specific treatments. There are many tools used by precision farmers to help them identify the variability and where it exists. In most cases, management units (MUs) are identified. This thesis includes two studies. One study focuses on a method to delineate MUs and the other focuses on creating a geographical information system (GIS) interface that incorporates the use of MUs into a crop simulation model. Overall, this will allow for the implementation of more efficient best management practices with intentions of enhancing the economic and environmental sustainability of crop production. The first study demonstrates and evaluates the creation of MUs for the purpose of precision farming. The two hydrologic factors, topography and water infiltration rates, were used to delineate MUs. The hydrology model within the spatial analyst extension of ArcView, a GIS, was used to create a subwatershed theme from the topography data, and soil maps from United States Department of Agriculture (USDA) Soil Conservation Service (SCS) were used to create an 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 within boundaries than MUs created using either slope or soil type methods. The second study presents a GIS interface for a crop simulation model. The interface allows the user to create the input files required by the model pertaining to three management updates, fertilization, irrigation, and cultivation. Since the model is a spatial model, there are different sets of input files for each MU in the field. The model is executed from within the GIS and then the output for each MU is returned. The output can also be viewed with the GIS.