Tuesday, November 14, 2006

Relating Soil Carbon and Hydrology to Sandy Hydric Soil Indicators.

Gerren Lanier, David Lindbo, and Michael Vepraskas. Norh Carolina State Univ, Williams Hall, Campus Box 7619, Raleigh, NC 27695

Soil morphological features are used to develop a list of field indicators that are used to identify hydric soils.  Sandy soil indicators are often viewed as problematic due to low iron contents making identification of redox depletions and concentrations difficult.  Thus many of the sandy hydric soil indictors rely on carbon accumulation due to anaerobic conditions within the upper 15 cm of the profile.  In order to better understand the dynamics of carbon accumulation and its relation to hydrology and soil redox status an experimental study site was chosen on the Outer Banks of NC to monitor hydrology, redox potential, and carbon content.  Fifteen soil plots were monitored along a stable dune containing members of the Fripp, Ousley, and Osier soil series.  Redox probes were installed in each plot in November of 2002 to depths of 15, 30, and 45 cm and were monitored weekly. Water table levels were recorded daily.  Soil cores were taken from each soil plot to depths of 60 cm, split based on horizon, and total carbon was determined for each horizon.  Additionally, the percent organic coated grains (black color), Munsell color, and quantitative color were determined.  Total carbon content increased with increasing duration of saturation and with decreasing redox status.  The percent coated grains also increased as duration of saturation increased.  It appears the carbon content may be usable as a proxy for hydrology in these soils.