VW05, VW25, VW45 (5, 25, and 45 cm)
Soil moisture probes were added in winter/spring 2006 (for Little Washita) and summer 2005 (for Fort Cobb). The soil water content is measured at depths of 5, 25, and 45 cm below the ground. Prior to December 2008 (for Little Washita) and March 2009 (for Fort Cobb), measurements were taken at 30-minute intervals. Since then, until January 2012 (for both networks), measurements were taken at 15-minute intervals. Since then, measurements have been taken at 5-minute intervals.
Stevens Hydra Probe
± 0.03 water fraction by volume in typical soil.