Three fields were selected near Hernando, Leland and Shaw in western Mississippi for EC_a mapping (using a Veris 3100 meter), soil fertility sampling on a 2.5-acre grid, determination of elevation, and topography. These fields were involved in an on-going SMART program, intended to demonstrate implementation of research based technology to improve production efficiency and farm profitability. Soil textures ranged from silt loam to clay. Measured physical and chemical soil properties were related to yield data generated from GPS-referenced yield monitors on farmer combines. Yields averaged 37, 55, and 57 bu/A in the fields near Hernando (nonirrigated), Leland (irrigated), and Shaw (irrigated), respectively. The standard deviations in yields were 6.5, 13.3, and 13.8 bu/A, respectively.