Hydric Soil Indicators Research Articles

Legacy Agricultural Terraces as a Sustainability Asset: A Rapid Assessment Technique

Former agricultural terraces in a suburban setting were analyzed for evidence of ecological benefits related to surface water runoff. Presence of hydric soils was utilized as an indicator of runoff velocity retardation and associated reduction of suspended contaminants in surface water. Soils were probed in various topographic positions within a terraced hillslope on the Johnson County Community College campus and assessed for hydric soil indicators using procedures published by the U.S. Department of Agriculture. The soils in the constructed terrace channels were found to be hydric, and the soils in the terrace ridges were found to be non-hydric. These findings indicate that the legacy terraces are contributing to improved water quality lower in the watershed even 30 years after the conversion of the land from agriculture to a college campus surrounded by suburban development. Finally, the methods utilized in this study are offered as an easily and rapidly deployed way for land owners to describe and doc...

Soil Color and US Northeast Aquods

Core Ideas Identifying hydric soils and depth to seasonal high water table is difficult in Spodosols. The specific criteria for classifying wet Spodosols need to change. Extractable Fe does not appear to contribute to the red color of wet Spodosols. An interaction between Al and humic substances may possibly contribute to the redder hues. Aquods commonly occur in wetland settings across a range of temperature regimes. Understanding their morphologies is critical to developing effective hydric soil indicators. In this study, we examined a range of wet Spodosols of the northeastern United States. We tested whether the red hues associated with wet spodic horizons are a function of humic (HA) and fulvic acids (FA) or Fe, and addressed questions related to hydric soil indicators, horizon designation, and soil classification. Only two of the 11 seasonally saturated Spodosols met current criteria for Aquods. Almost all of the 24 Bh, Bhs, or Bhsm horizons had 3 to 10 times more ammonium oxalate extractable Al than Fe (mean Fe was <0.15%), yet only three pedons met the current criteria for “Al” great groups. We found no consistently applied color or sesquioxide content criteria for separating Bh from Bhs horizons. These results suggest that criteria for horizon designation and classification of Aquods need to be reconsidered. There were no relationships between extractable Fe and hue (p = 0.50). Weak correlation coefficients (−0.40 and −0.39; p = 0.051 and 0.057) between hue and FA and HA suggest little support for red hues being primarily a function of HA or FA. The significant relationship between Al and hue (−0.46; p = 0.025) and the strong correlation between Al and both HA and FA (0.87 and 0.86; p < 0.001) suggest a possible interaction between Al and the humic substances resulting in redder hues. We found more than twice as much HA in the spodic horizons as FA and concluded that FA is the precursor of HA in US Northeast spodic horizons.

Profiles in History

1940S On April 5, 2014, a member of “the greatest generation,” Hal L. Hill passed away in Bakersfield, CA. Hal Hill was born in Syracuse, NE in 1920. He graduated from the University of Nebraska and also served in World War II. After the war, Hill worked for 28 yr in the United States Department of Agriculture–Soil Conservation Service. Hal Hill in uniform during World War II. Hill's career with USDA-SCS began in Nebraska where he worked during the mapping season, and during the cold snowy winters he was detailed to the South to help finish ongoing soil surveys in Louisiana. Hill later moved to California's San Joaquin Valley, where as a USDA-SCS employee working with University of California soil scientists, he helped finish field work for the Soil Survey of Madera Area, California. He also worked on the Soil Survey of Eastern Fresno Area, California before completing his career in Bakersfield, where he was the project leader for the Soil Survey of Kern County, California, Southeastern Part. Information courtesy of Kerry Arroues and Kim Chang, soil scientists, USDA-NRCS (retired), and Hill's obituary as printed in the Bakersfield Californian. 1991 The Northeast Regional Soil Judging Competition was hosted by Delaware Valley College (DVC) in 1991. Preparing a soil pit for judging on a glacial outwash plain near Washington's Crossing, PA are (left to right): Paul Golrick, Del Val Soil Consultants, Inc.; Joe Valentine, Del Val Soil Consultants, Inc. and adjunct instructor at DVC; Pennsylvania Assistant State Soil Scientist–Correlation, Ed White, USDA-SCS; Scott Anderson, Soil Survey Party Leader, USDA-SCS; and Milton Cortes, Soil Scientist, USDA-SCS. Soil judging in southeastern Pennsylvania. Joe Valentine, a consulting soil scientist, continues as an adjunct instructor at DVC, which hosted the 2014 National Soil Judging Competition in April. Joe was the event coordinator. Ed White retired in 2012 as State Soil Scientist of Pennsylvanian and assisted with the scoring at the 2014 national event. Scott Anderson is now Senior Regional Soil Scientist at the Regional Soil Survey Office in Auburn, AL, while Milton Cortes is Assistant State Soil Scientist in Raleigh, NC. Paul Golrick is a soil scientist and a professional geologist at Penn's Trail Environmental, Inc., where he is also a partner in the company. Paul gave a presentation on local geology at the 2014 national event. Photo courtesy of John Chibirka, USDA-NRCS soil scientist in Pennsylvania, who also assisted with the official soil descriptions for the 1991 regional contest. 2010 The 2010 Florida Association of Environmental Soil Scientists (FAESS) Hydric Soils Workshop (HSW) was held in Indian River County, FL, near Vero Beach. In the photo above, soil scientist Frank Watts (seated), USDA-NRCS (retired) and pedologist of AAA Soil Consultants, administers the soil texture demonstration, which is a part of the FAESS HSW's field demonstrations. Participants practiced their abilities to determine different soil textures. On the table shown above, textures for fine sand, loamy fine sand, fine sandy loam, sandy clay loam, and sandy clay are in the foreground, while the darker samples in the background include mucky mineral (mucky fine sand) and muck textures, both of which are hydric soil indicators. Soil texturing at a Hydric Soils Workshop. FAESS conducts the popular Hydric Soils Workshop annually in April. The workshop location rotates around Florida, as soil characteristics vary geographically. The HSWs are comprised of morning classroom presentations by soil science experts, including professional consultants, university professors, and environmental regulators. A guided soils field trip conducted by members of the FAESS in the afternoon allows participants to gain hands-on experience identifying hydric soils in the field. FAESS Hydric Soils Workshops are popular and are attended each year by environmental consultants, engineers, Department of Health personnel, university students, and others. Information and photo courtesy of FAESS.

Profiles in History

1990 When it comes to loving soils, few individuals have the kind of enthusiasm that Frank Watts of Hilliard, FL has exhibited for many years. Watts, who served for 35 years as a soil scientist with USDA-SCS/NRCS, led efforts in the late 1980s to establish Myakka fine sand as Florida's official state soil. Above, Watts poses with a Myakka monolith in 1990. Frank Watts with Florida's state soil monolith. Watts, a Kentucky native, received his B.S. and M.S. degrees in soil science from Murray State University, Murray, KY. He began his career in Kentucky with USDA-SCS in 1968 by contributing to two published soil surveys. In 1970, Watts transferred to Florida, where he contributed to 16 published soil surveys throughout the state and served as soil survey project leader in six counties before retiring in 2003. He was instrumental in developing methodology to interpret soil morphological features for determining depth to seasonal high water tables and in developing hydric soil indicators. Frank Watts was the senior author of “History of Establishing a State Soil: Florida's Myakka Fine Sand,” and “Determining Depths to the Seasonal High Water Table and Hydric Soils in Florida,” which were publish in Soil Survey Horizons in the early 1990s. Watts is the senior author of Soils of Florida, a book published by the Soil Science Society of America in 2008, which shows the beauty of soils with its 168 color photos of Florida soil profiles. 1969 Kan Kim Chang, best known as Kim Chang, is shown describing a Milham soil while working on the Soil Survey of Kern County, California, Northwestern Part. Upon graduating from California Polytechnic State University in San Luis Obispo in 1959, Chang was hired as a fulltime soil scientist by USDA-SCS. After being drafted in 1961, Chang served for two years in the U.S. Army Corps of Engineers, testing soils, asphalt, and concrete. Upon returning to USDA-SCS in 1963, Chang worked on the Soil Survey of Eastern Fresno Area, California, prior to his project leader work on the Soil Survey of Kern County, Northwestern Part, which he authored in 1988. Kim Chang describes soil in California's San Joaquin Valley. Chang completed the second half of his illustrious 43-year career as the Area Soil Scientist for the USDA-NRCS in Fresno, CA. He was known as an excellent field soil scientist and trainer of soil scientists. In his job as Area Soil Scientist he was responsible for field reviews of soil surveys being conducted by three U.S. government agencies. As an Area Soil Scientist, Chang worked as a soil liaison with many USDA-NRCS field offices throughout California. He is also known for the valuable assistance he has provided to FFA land judging competitions in the San Joaquin Valley for more than 50 years. Information courtesy of Kerry Arroues, NRCS, Soil Scientist (retired), Hanford, CA. 1939 An accelerated program of soil survey and classification was initiated within the Tennessee Valley in 1935, shortly after the inception of the TVA. It developed as a cooperative project within the overall objectives described in the Memorandum of Understanding signed on November 20, 1934, by TVA, USDA, and the agricultural colleges of the seven valley states, specifying for a coordinated program of agricultural research, extension, and land-use planning. The need for an up-to-date inventory of available soil resources was recognized as a necessity for making adjustments in land use and development of agriculture in the Tennessee Valley region. Flooding, soil erosion, and abuse of farmland were very serious problems throughout the Tennessee Valley at this time. At initiation of the project, only 38 of the Tennessee River watershed counties had soil surveys, and most of these were inadequate, even by 1935 standards, and needed updating. Soil surveyors in the Tennessee Valley. The photograph above was taken in May of 1939 during a field inspection trip in Scott County, VA. Soil surveyors are (left to right): H.H. Perry, H.C. Porter, D.D. Mason, J.W. Moon (Regional Inspector, Soil Survey, USDA), Dr. S.S. Obenshain (Virginia Polytechnic Institute Soil Classification Project Leader), R.C. Jurney, C.S. Coleman, E.F. Henry, and A.C. Orvedal. Information courtesy of Dr. John M. Soileau, Research Soil Scientist (retired), Tennessee Valley Authority, Florence, AL.

Profiles in History

2012 Members of the Professional Soil Classifiers Association of Alabama (PSCAA) convened on the Gulf Coast in Baldwin County for their 37th annual meeting and field tour in June 2012. The field tour was developed by USDA-NRCS District Conservationist and PSCAA President Joey Koptis along with members Greg Brannon and Jerome Langlinais, USDA-NRCS soil scientists, and Frank Cochran, USDA-NRCS soil conservationist. One of the field tour stops was to a pitcher plant bog where small spade holes were excavated and Joey Koptis led discussions on hydric soil indicators and the formation of a spodic horizon in one of the pedons. (left to right) Sanderson Page, Joey Koptis, and Jerome Langlinais examining hydric soil indicators. Other stops on the field tour included backhoe pits in a Malbis soil and a soil similar to the Robertsdale series. Discussions at these sites focused on plinthite, fragic properties and soil drainage. PSCAA Members Examine Hydric Soil Indicators The Professional Soil Classifiers Association of Alabama was organized by a small group of soil scientists in 1975 to promote the profession of soil classification and to further the increase and dissemination of information concerning all aspects of soil science. For more information on PSCAA, visit their website at www.alabamasoilclassifiers.org. Photo and information courtesy of PSCAA. 2011 In 2011, field work in the 48 contiguous states of the United States was completed for the Rapid Assessment of U.S. Soil Carbon (RaCA), a project initiated by the USDA-NRCS Soil Science Division in 2010. The project was a huge undertaking that involved the collection of 144,833 samples that were collected from the upper one meter of 32,084 soil profiles at 6,017 randomly selected locations. National Resources Inventory (NRI) sites were used as the basis for random selection of sample sites stratified by soil group and land use/land cover. At each location soil morphology and landscape characteristics were described, and limited vegetation and management information was collected. The collection and analysis of the many samples involved more than 300 soil scientists working in the National Cooperative Soil Survey Program, including 24 universities across the nation. A Toast to the Completion of RaCA Fieldwork Pictured above are Bev Harben and Phil Smith, USDA-NRCS soil scientists, “toasting” with bulk density sampling cores while celebrating the completion of their final sampling site in Solano County, California. Source: USDA-NRCS Soil Science Division, http://soils.usda.gov/survey/raca/. Photo courtesy of MLRA Soil Survey Office 2-TEM, Templeton, CA. 2004 Careers that span 60 years are a rarity, and Terry Cook is that rare soil scientist who has worked in the field from 1953 through 2013. In 1953, he was one of three crew members selected from Cal Poly, San Luis Obispo by a National Park Service Ranger to work on severely eroding Ellis Meadow at an elevation of 2,792 meters. This meadow in Kings Canyon National Park was beginning to rapidly erode as a result of past grazing practices. In 1955, he was the crew chief who selected his own crew from the Cal Poly Soils Department. Erosion control measures, all installed by hand, included basket dams, posts and anchors, chicken wire, branches and thatch, and even large logs on the eroding edge of the meadow, as shown in the photo, that were successfully placed to slow the water down and trap sediment. Terry Cook Stands on Log He Placed in 1955 Terry Cook has led a very diverse career and has provided superb leadership in soil science for many individuals and groups. From 1955 to 1983, Terry Cook worked for the Soil Conservation Service (SCS) in California as a Soil Survey Party Leader, Area Soil Specialist, and State and Regional Correlator. From 1983 through 1990, he worked as an International Training Specialist for USDA Soil Conservation Service with Soil Management Support Services (SMSS). This work took him to many different countries where he conducted workshops, meetings, and training forums. He has been a soil consultant in Davis, CA since he retired from SCS in 1990. He has been an active participant and field trip organizer in many soil-related organizations. Photo and information courtesy of Kerry Arroues, retired USDA-NRCS Soil Scientist, Hanford, CA.

Application of Magnetic Susceptibility for Wetlands Delineation

Wetlands are natural resources that are protected under federal regulations; therefore, the delineation of wetlands is necessary to ensure their protection. Standard methods used for delineating wetlands can be time consuming, or a wetland could be problematic, i.e., lacking hydrophytic vegetation or hydric soil indicators, or periodically lacking hydrologic indicators. A magnetic susceptibility study could be an additional technique used to aid in the delineation process. A study using magnetic susceptibility was undertaken in central Mississippi to identify the transitional zone or boundary between non-hydric (uplands) and hydric (wetlands) soils. The soils were silt loam with a minor percentage of sand. A survey line that traversed the transitional zone between wetland and upland on each end of the transect was revisited four times during a single year and once two years later. One survey was conducted a few weeks after the winter inundation (moderately wet soil conditions), one was conducted several months after inundation but immediately after some heavy rainfall (moderately wet soil conditions), and two were conducted several weeks or months after inundation or significant rainfall (dry soil conditions). There were measurable differences between the magnetic susceptibility values collected in the upland and wetland regions during each survey. One transitional zone was easily identified using magnetic susceptibility, exhibiting a sharp decrease in susceptibility values between the upland and wetland. The other transitional zone contained an intermediate ridge, which made demarcation of the zone less obvious. The measured magnetic susceptibility values were comparable for the respective upland, transition, and wetland regions, and the characteristics of the curves were similar for all time-periods. Overall, magnetic susceptibility proved to be a successful method for delineating a wetland in this area.

Transfer and transformation of soil iron and implications for hydrogeomorpholocial changes in Naoli River Catchment, Sanjiang Plain, Northeast China

Wetland soils are characterized by alternating redox process due to the fluctuation of waterlogged conditions. Iron is an important redox substance, and its transfer and transformation in the wetland ecosystem could be an effective indicator for the environment changes. In this paper, we selected the Naoli River catchment in the Sanjiang Plain, Northeast China as the study area to analyze the dynamics of transfer and transformation of soil iron, and the relationship between iron content change and environmental factors. The results show that the total and crystalline iron contents reach the peak in the depth of 60 cm in soil profile, while the amorphous iron content is higher in the topsoil. In the upper reaches, from the low to high landscape positions, the total and crystalline iron contents decrease from 62.98 g/kg to 41.61 g/kg, 22.82 g/kg to 10.53 g/kg respectively, while the amorphous iron content increases from 2.42 g/kg to 8.88 g/kg. Amorphous iron content has positive correlation with organic matter and soil water contents, while negative correlation with pH. Moreover, both the crystalline and amorphous iron contents present no correlation with total iron content, indicating that environmental factors play a more important role in the transfer and transformation of iron other than the content of the total iron. Different redoximorphic features were found along the soil profile due to the transfer and transformation of iron. E and B horizons of wetland soil in the study area have a matrix Chroma 2 or less, and all the soil types can meet the criteria of American hydric soil indicators except albic soil.

Evaluation of Soil Properties and Hydric Soil Indicators for Vernal Pool Catenas in California

Evaluation of Soil Properties and Hydric Soil Indicators for Vernal Pool Catenas in California

Hydrologic Signature Analysis of Select Organic Hydric Soil Indicators in Northeastern Florida

The magnitude, duration, and return intervals of surface water flooding and dewatering of the landward extent of the hydric soil indicators muck (LM), histic epipedon (LHE), and Histosol (LH) were quantitatively defined, providing a better understanding of the hydrologic conditions maintaining these hydric soil indicators. Land surface elevations were determined for the LM, LHE, and LH at 16 lakes with long‐term (30–60‐yr) modeled or gauged hydrologic data. The probability of flooding and dewatering of the elevations of the LM, LHE, and LH were determined from frequency analysis of hydrologic data from each lake. The resulting hydrologic signatures for the LM, LHE, and LH are composed of magnitude and return interval of 1, 30, 90, 183, 274, and 365‐d duration flooding and dewatering events. As an example, the LM, LHE, and LH were flooded for 30 continuous days with average annual probabilities of 42, 65, and 77%, respectively. As a second example, the LM, LHE, and LH were dewatered for 365 continuous days with average annual probabilities of 49, 24, and 16%, respectively. Probabilities of flooding and dewatering for the LM, LHE, and LH are presented for 1, 30, 90, 183, 274, and 365‐d durations. Mean hydrologic signatures reduce variability and may be considered representative of each soil characteristic. Quantitatively defining the hydrology associated with the presence of the LM, LHE, and LH as well as other soil characteristics is essential for environmental protection, assessment of hydrologic impacts, wetlands restoration, wetlands creation, and other environmental management applications.

Evaluation of Soil Properties and Hydric Soil Indicators for Vernal Pool Catenas in California

Vernal pool soils in California's Mediterranean climate experience extremes in pedogenesis driven by prolonged saturation to extended desiccation. Four northern California vernal pool soil catenas (summit, rim, and basin) were assessed to determine how soil properties and hydric soil indicators vary in response to duration of standing water and landscape position. Each catena had differences in parent material or degree of soil development. Soil properties differed subtly across each microtopographic sequence. In the well‐developed soils, the geochemical signature of horizons overlying the duripans changed sharply compared with horizons below the restrictive layers, suggesting polygenic origins of the soil profiles. The presence and abundance of redoximorphic features (RMFs) in profiles corresponded poorly with the duration of standing water at the four sites. Instead, the abundance of RMFs coincided better with the thickness of the soil above the restrictive horizons in all settings with duripans. Hydric soils were identified in the basin positions of each catena. Most rim positions contained hydric soils and most summit positions had soils that were not hydric. Indicators F8 (redox depressions) and TF2 (test indicator for red parent materials) were most commonly applied. None of the vernal pool catena soils met F9 (vernal pools hydric soil indicator), thus the hydric soil criteria for vernal pools may need to be revised.

Appalachian Mine Soil Morphology and Properties

Surface coal mining and reclamation methods in the Appalachians have changed dramatically since the passage of the Surface Mining Control and Reclamation Act (SMCRA) of 1977 and subsequent improvements in mining and reclamation technology. In this study, 30 pre‐SMCRA mine soil profiles (4–20 yr old) were examined and sampled in 1980 and compared with 20 mine soil profiles (8–13 yr old) described in the same area in 2002 after it had been completely remined by modern deep cut methods. Mine soils in both sampling years had high rock fragment content (42–81%), relatively well‐developed A horizons, and generally exhibited A‐C or A‐AC‐C horizonation. Although six Bw horizons were described in 1980, only two met all requirements for cambic horizons. The 1980 mine soils developed in overburden dominated by oxidized, preweathered material due to relatively shallow mining cuts. The 1980 mine soils had lower rock fragment content, finer textures, lower pH, and tended to be more heterogeneous in horizonation, morphology, and texture than soils observed in 2002, which had formed primarily in unweathered overburden from deeper cuts. Half the pedons sampled in both years had densic materials within 70 cm of the surface. Four poorly to very poorly drained soil profiles were described in each sampling year containing distinct hydric soil indicators in surface horizons. While older pre‐SMCRA mine soils do have many properties in common with newer mine soils, their properties are highly influenced by the fact that they generally have formed in more weathered overburden from higher in the geologic column. Overall, Appalachian mine soils are much more complex in subsoil morphology than commonly assumed, and differential compaction greatly complicates their internal drainage and limits their overall productivity potential.

English

Surface coal mining and reclamation methods in the Appalachians have changed dramatically since the passage of the Surface Mining Control and Reclamation Act (SMCRA) of 1977 and subsequent improvements in mining and reclamation technology. In this study, 30 pre-SMCRA mine soil profiles (4-20 yr old) were examined and sampled in 1980 and compared to 20 mine soil profiles (8-13 yr old) described in the same area in 2002 after it had been completely re- mined by modern deep cut methods. Mine soils in both sampling years had high rock fragment content (42 to 81%), relatively well-developed A horizons, and generally exhibited A-C, or A-AC-C horizonation. Although six Bw horizons were described in 1980, only two met all requirements for cambic horizons. The 1980 mine soils developed in overburden dominated by oxidized, pre-weathered material due to relatively shallow mining cuts. The 1980 mine soils had lower rock fragment content, finer textures, lower pH, and tended to be more heterogeneous in horizonation, morphology, and texture than soils observed in 2002, which had formed primarily in unweathered overburden from deeper cuts. Half the pedons sampled in both years had densic materials within 70 cm of the surface. Four poorly to very poorly drained soil profiles were described in each sampling year containing distinct hydric soil indicators in surface horizons. While older pre-SMCRA mine soils do have many properties in common with newer mine soils, their properties are highly influenced by the fact that they generally have formed in more weathered overburden from higher in the geologic column. Overall, Appalachian mine soils are much more complex in subsoil morphology than commonly assumed, and differential compaction greatly complicates their internal drainage and limits their overall productivity potential.

Hydric Soils in a Southeastern Oregon Vernal Pool

Vernal pools on the High Lava Plain of the northern Great Basin become ponded in most years, but their soils exhibit weak redoximorphic features indicative of hydric conditions. We studied the hydrology, temperature, redox potentials, soil chemistry, and soil morphology of a vernal pool to determine if the soils are hydric, and to evaluate hydric soil field indicators. We collected data for 3 yr from piezometers, Pt electrodes, and thermocouples. Soil and water samples were analyzed for pH, organic C, and extractable Fe and Mn. Soils were ponded from January through April or May, but subsurface saturation was never detected. Soil temperatures 50 cm below the surface rose above 5°C by March. Clayey Bt horizons perched water and limited saturation to the upper 10 cm. Redox potentials at a 5-cm depth were often between 200 and 300 mV, indicating anaerobic conditions, but producing soluble Fe 2+ concentrations <1 mg L 1 . Extractable soil Fe contents indicated Fe depletion from pool surface horizons and accumulation at or near the upper Btl horizon. Depletions and concentrations did not satisfy the criteria of any current hydric soil indicators. We recommend development of new indicators based on acceptance of fewer, less distinct redox concentrations for recognition of a depleted A horizon, and on presence of a thin zone containing redox concentrations located in the upper part of the near-surface perching horizon.

Long‐Term Evaluations of Seasonally Saturated “Wetlands” in Western Kentucky

A research program was initiated in 1993 to monitor water‐table depth, redox potential, and soil matric potential at four sites. The selected sites were woodlands with water tables present at or near the soil surface during late winter and spring. Soil morphology was described and permanent monitoring instruments were installed on eight soils. Hydrosequences of three soils, which represented an Endoaquept‐Fragiaqualf‐Fraglossudalf and a Fraguaqualf‐Fraglossudalf‐Fraglossudalf sequences, were studied at two sites. An Epiaqualf and a Fragiaqualf were monitored at each of the remaining sites. Six of the eight soils experienced wetland hydrology in most years, while the other two exhibited sporadic saturation events above 25 cm. Saturated conditions occurred mainly in late winter and spring, with longest duration in the lowest landscape positions. On the wettest soils, redox levels &lt;200 mV developed during late winter and continued into the growing season. Of the six soils meeting the hydrology criterion only three experienced both, functional hydric soil conditions (&lt;200 mV redox potential) and exhibited definitive hydric soil indicators. However, hydric soil indicators were also present in two of the three other soils that developed only moderately reduced conditions (&lt;350 mV). In contrast, only one of the six soils with wetland hydrology did not meet the hydrophytic vegetation criterion, while one nonhydric soil met the criterion. The presence, depth, and quality of fragipans appeared to influence the expression of hydric conditions through episaturation, endosaturation, and amphisaturation processes, creating a range of aquic and oxyaquic conditions. These findings emphasize the complexity of seasonally saturated wetland ecosystems and the difficulties in assessing and implementing wetland identification and delineation criteria.

MICROMORPHOLOGY OF SEASONALLY SATURATED SOILS IN CARBONIFEROUS GLACIAL TILL

Soils formed in dark-colored glacial till (chroma 3, value < 4) are common in southern New England. The low chroma, low-value colors reflect the carboniferous nature of the sedimentary and metasedimentary rocks that compose the till. Much of this till is very dense, resulting in soils with seasonal high water tables. The inherent dark colors of the soils make it difficult to use hydromorphic features to estimate depths of seasonal saturation. We examined thin sections to determine if micromorphology could be used to elucidate the apparent lack of hydromorphic features in seasonally saturated Bw horizons formed in dark till. Observation wells were monitored for 18 months to establish water table seasonal fluctuations in soils on shoulder positions. Hydromorphic features were examined in the field and in thin sections to correlate with the seasonal water table levels. Soils showed seasonal saturation and were classified as Humic Epiaquepts and Typic Humaquepts. Water levels frequently rose into the upper Bw horizons. One of the soils examined met hydric soil criteria based on hydrology. Hydric soil indicators such as a depleted matrix (F3) were absent. The dark parent materials were most likely preventing the observation of morphologic indicators of reducing conditions. Redoximorphic features were not identified by field observations in the seasonally saturated upper Bw horizons. Thin sections of the upper Bw horizons revealed redoximorphic features that were too faint, fine, or had boundaries too diffuse to be observed in the field. Identifying hydromorphic features in lower horizons and, with the aid of magnification, tracing these features carefully into overlying horizons may help identify the depth to aquic conditions in low chroma-low value seasonally saturated soils.

Using Hydric Soil Indicators in Disturbed Soils

Using Hydric Soil Indicators in Disturbed Soils

Environmental gradients and identification of wetlands in north-central Florida

Vegetation composition, soil morphology, and hydrology were characterized along wetland-to-upland gradients at six forested sites in north-central Florida to compare results of Federal wetland delineation methods with 3–5 yr of hydrologic data. Wetland and non-wetland identifications were supported by hydrology data in eight of nine plant communities. Lack of hydric soil indicators and hydrophytic vegetation in two upland communities (scrub and mixed mesic hardwoods) agreed with a deep water table. Six wetland communities (cypress dome, cypress strand, bayhead, cypress/bayhead, red maple/oak swamp, and cedar swamp) with field indicators of wetland hydrology, hydrophytic vegetation, and hydric soils were inundated or had water tables at or near the ground surface at least 5% of the growing season in most years., Flatwoods communities, however, occurred at intermediate positions on the moisture gradient and could not be consistently identified as wetland or upland communities. Identification of flatwoods as wetlands depended on wetland delineation method and was not usually supported by hydrologic measurements. In the flatwoods community, soil properties and vegetation composition were correlated with the mean and standard deviation of water-table depths, as well as the depth continuously exceeded by the water table at least 5% of the growing season in most years. Various hydrologic parameters need to be considered in addition to the 5% exceedence level currently used in Federal wetland delineation guidance when characterizing wetland conditions in low-gradient areas such as flatwoods.

Development and application of hydric soil indicators in Florida

The hydric soil definition and hydric soil criteria are often insufficient for use in field identification/delineation of hydric soils. This paper traces the experiences soil scientists and other wetland scientists had in Florida to properly identify, understand, and use hydric soil indicators to identify those soils that fit both the hydric soil definition and the hydric soil criteria. The hydric soil indicators that properly identify soils that fit the definition and criteria in Florida are as follows: hydrogen sulfide, organic bodies, stratified layers, muck, mucky texture, dark surface, stripped matrix, redox concentrations, gleyed matrix, depleted matrix, iron manganese masses, umbric epipedon, thick mollic epipedon, or marl. Exact thicknesses, depths, percentages, and colors that are required for each of the hydric soil indicators have been developed. Because of the knowledge gained from intense observations of morphological features in soils for hydric soil determinations scientists were able to transfer this technological ability to include the estimation of seasonal high water tables for all soils in Florida.