Soil Indicators and Site Evaluation Form By Helen Lovell, MS CHEP and Monica Lopez, MS, CHEP
Seasonal High Water Table
highest level of a saturated zone in the soil in most years.
A water table that is seasonally high for LESS THAN ONE MONTH is not indicated in the table (Soil and Water Features Table in Soil Surveys).
Soil Color - the dominant morphological feature used to predict the SHWT
Matrix – dominant (background) color of soil profile
Mottle – splotch of color, opposite of matrix
Redoximorphic Features – specific features formed from oxidation-reduction reactions used to predict seasonal high water tables, includes certain types and amounts of mottles. They are caused by the presence of water and minerals in the soil.
Stripped Matrix - splotchy color pattern with no discernible dominance by any one color.
• Organic Matter (OM)
• Gives soil dark brown to black color
• Compounds and Elements
1 . Iron-oxides
• Gives soil red to yellowish brown
2. Manganese oxides
• Gives soil dark purple color
OM Relation to Soil Drainage
Anaerobic decomposition rates for OM are
about 10-30% of aerobic decomposition rates (Hammer, 1992 and Debusk and Reddy, 1998)
The wetter the soil the greater the OM content
The greater the organic matter content the
darker the soil
Wet soils are dark in color (lower chroma or value)
Fe-Oxides Relation to Soil Drainage
Reduction and oxidation of iron is
reflected in the soil morphology
Areas of reduced iron are gray (low chroma)
Areas of oxidized iron are red to yellowish
brown (high chroma)
Redoximorphic features form under
saturation (anaerobic conditions)
Organic Matter (OM)- based indicators such as dark surface or stripped matrix will be important.
In sandy discharge wetlands, dissolved iron can be brought into the soil that otherwise had no iron. The result can be small concentrations of oxidized iron, which would be an example of a Sandy Redox indicator (hydric soil indicator).
In sandy recharge wetlands, iron/carbon can be removed, leading to a Stripped Matrix indicator (hydric soil indicator).
Must be have distinct or prominent contrast with the matrix and have diffuse boundaries