Hydric Soils Class

Field Indicators of Hydric (Wetland) Soils in the Atlantic Coastal Plain, Sponsored by the Mid-Atlantic Association of Professional Soil Scientists (MAPSS)

The one-day soils class was held at the Lions Club Camp Merrick, a waterfront property on the Potomac River in Nanjemoy, Charles County, MD.


The workshop concentrated on the development, application and identification of hydric soil indicators in the coastal plain.  The instructors were Gary Jellick, Lenore Vasilas, Martin Rabenhorst and Jim Brewer.


Gary Jellick handed out his “field cheat sheet” entitled Hydric Soil Boundary Indicators, emphasizing that the most common hydric soil indicators as noted on the Wetland Determination Data Form are Depleted Matrix (F3) for loamy and clayey soils and Sandy Redox (S5) for sandy soils.


The morning technical session provided an overview of the development of the indicators, pedogenic processes associated with hydric soils and the interpretation of soil information related to hydric soils.


MAPSS also handed-out a booklet entitled Field Indicators of Hydric Soils in the United States, A Guide for Identifying and Delineating Hydric Soils, Version 7.0.  An extracted guide for how to interpret soils analyzed for the purpose of wetland delineation can be found in the Regional Supplements to the Corps of Engineers Wetland Delineation Manuals, for the Coastal Plain and Piedmont.

The afternoon session provided training in the field identification of hydric soil indicators in sandy, clayey and organic soils.


We looked at five pits that were excavated using a back-hoe.  Four of the five pits were along and/or near nontidal wetland boundaries and one was clearly well within a wetland having obvious F3, depleted matrix conditions (a layer that had a depleted matrix with 60% or more chroma of 2 or less, and has a minimum thickness of 2-inches within the upper 6-inches of soil, or 6-inches starting within 10-inches of the soil surface).


The four other pits were designed to be close-calls, questionable as to whether or not they would be considered wetland or upland soils.

At each pit we broke-up into teams and prepared a profile description, describing the depth needed to document the indicator(s) or confirm the absence of indicators.  We were advised to be mindful that hydric soils usually extend a little further back from the wetland delineation line.  When considering wetland vegetation and hydrology, wetland soils should be overt and then transitioning toward upland soils as you move away from your flagged delineation line.


This exercise allowed us to be “calibrated” to the instructors and reduce subjectivity.  It is important to carry a measuring tape and a small spray bottle container of water when doing soils work for profile descriptions.  MAPSS strongly recommends that Munsell Soil Color books be updated at least every four years of use.  Forestry Suppliers sells the book and also the heavily used 10YR and 7.5 page inserts, as they are amongst the most common for our use.


MAPSS wanted us to know that Piedmont Floodplain Soils (F19) have had a language change, taking out the word “active” in their floodplain description.  A new hydric soil indicator has been added, which is known as Red Parent Material Soils (F21), with all this information being found at http://soils.usda.gov/technical/.


Remember also the few keys to soils that lack field indicators as a first-cut when investigating soils.

Dig a hole to 6-inches, making sure to not include the fibric ‘O’ organic horizon.  Does organic soil material or mucky modified layers exist?  Does chroma of 2 or less exist?  Do you see any distinct or prominent redox concentrations of soft masses (mottles) or pole linings?  Is there a hydrogen sulfide odor (rotten eggs)?  Check landscape position, are you in a depression, on a floodplain, near a marsh or close to mean high tide?  If you answer no to these questions, the soil will not meet an indicator.  Move on to your next site.

Thank you Gary Jellick and MAPSS.