In May 2010, a soil moisture sensor intercomparison study was begun in Marena, Oklahoma.  This effort is designed to serve as a foundation for incorporating diverse soil moisture networks into the Soil Moisture Active Passive (SMAP) Calibration and Validation program.  Various soil moisture sensors, which are currently used throughout the world, were deployed throughout a rangeland pasture to collect a long term soil moisture time series and develop a qualitative assessment of how these sensors can be merged into a single global soil moisture database for satellite remote sensing calibration and validation.  Regular sampling of gravimetric soil moisture is conducted to determine an absolute ground truth for the electronic time series.  Initial results include an assessment of the ease of deployment and installation, as well as the sensitivity to significant precipitation amounts.