Toxonomic Classification and Hydric Status of Sharkey Soils

JANUARY 1997

EXECUTIVE SUMMARY

Based on recently published information by Mississippi Agricultural & Forestry Experiment Station, the Mississippi Delta Council requested that the Natural Resources Conservation Service re-evaluate the taxonomic classification and hydric status of the Sharkey series in Mississippi. Sharkey soils have been identified throughout the Southern Mississippi Valley Alluvium Major Land Resource Area. Approximately 4.2 million acres have been mapped and correlated.

In response to this request, a team was formed to study Sharkey soils in Arkansas, Louisiana and Mississippi. The NRCS was represented by soil scientists of Arkansas, Louisiana, Mississippi, Kentucky, and Tennessee; the Wetlands Science Institute; the Mississippi Delta Wetlands Team; and the National Soil Survey Center. State Agriculture Experiment Stations were represented by NCSS cooperators from the University of Arkansas, Louisiana State University Agricultural Center, and Mississippi State University. The U.S. Army Corps of Engineers was represented by a soil scientist from the Waterways Experiment Station, Vicksburg, MS, and an environmental specialist from the Vicksburg District. Two retired NRCS soil scientists that have extensive experience with Vertisols and hydric soils also participated in the study.

A total of fourteen sites were visited during the week of January 6-10, 1997. Six sites were located in central and northern Louisiana; two sites were in southern Arkansas and six sites were in central Mississippi. The taxonomic classification and hydric status was determined at each site. A brief vegetation survey was made along with tests for iron reduction with a , a 1 -dipyridyl. The geomorphic setting was also determined at each site.

A review of research data presented and study of Sharkey soils in the field, resulted in the following conclusions, recommendations and actions items.

SUMMARY OF CONCLUSIONS

1. The presence or absence of a soil on the hydric soils lists is not conclusive that the soil is hydric or non-hydric. On-site visits using approved field indicators of hydric soils must be used to identify and delineate hydric soils.

2. The field study verified that there is a hydric component and a non-hydric component within the Sharkey series. This is true of many soils on the hydric lists, and emphases why on-site visits using approved field indicators for hydric soils are required to identify and delineate the hydric components of soils. The Sharkey series should remain on the national hydric soils list. However, because of the confusion caused by the list, it was generally agreed that the list should no longer be maintained, or published.

3. Public understanding is lacking related to the proper use of the hydric soils lists as an off-site tool for identifying potential areas of hydric soils. There is also a limited knowledge of field indicators of hydric soils and the requirement to use them on-site to identify and delineate hydric soils.

4. The taxonomic classification of the Sharkey series should be changed from Inceptisols to Vertisols, but unresolved issues remain related to classification below the order level. These unresolved classification issues do not affect the hydric status of Sharkey soils, since taxonomic classification criteria, and hydric soils criteria are not the same.

5. Based on Keys To Soil Taxonomy, Seventh Edition, 1996, there are other taxonomic classes within the present concept of the Sharkey series. This is true for other soil series in MLRA 131, and supports the need for soil survey updates under the MLRA soil survey project concept.

6. There are unresolved questions related to measuring saturation and reduction in Vertisols in order to address taxonomic classification issues. Agreement needs to be reached on: 1) a definition of saturation and reduction; 2) procedures for measuring saturation and reduction; 3) when to measure saturation and reduction. Changes to Soil Taxonomy may be necessary.

7. The workload related to solving taxonomic classification problems and updating soil surveys in MLRA 131 is enormous. There is an inadequate staff of soil scientists to do the field work and funds are not presently available to support the needed research.

8. The hydric soil indicators were developed predominantly by correlating soil redoximorphic features to wetland boundaries as identified and delineated by wetland ecologists using only non-agricultural sites. Little research has been done to correlate the indicators to saturated soil conditions. This correlation needs to be made to support the definition and concept of hydric soils.

RECOMMENDATIONS

1. It is recommended that Sharkey soils remain on the national hydric soils list. However, because of the confusion caused by the list, it was generally agreed that the list should no longer be maintained, or published.

2. It is recommended that the Sharkey series not be split into different series based solely on the fact that the present concept of the series includes hydric and non-hydric components. We need to emphasize helping people understand that criteria for taxonomic classification, upon which soil surveys are based, are not the same as criteria for hydric soils.

3. It is recommended that all map units of Sharkey soils be placed on the appropriate local hydric soils list with the approximate percentage of hydric and non-hydric components.

4. It is recommended that all wetland scientists in government service and in the private sector begin immediately testing field indicator TF11 and provide either negative or positive comments along with supporting documentation.

5. It is recommended that, other soils within Land Resource Region O that have properties similar to Sharkey and occur on similar landscapes be studied to determine if they also have hydric and non-hydric components.

6. It is recommended that more efforts be made to correlate the field indicators for hydric soils to research studies that measure soil saturation and redox potential. This is to confirm that these indicators reflect soils formed under conditions that develop anaerobic conditions in the upper part, as stated in the hydric soil definition.

7. It is recommended that better guidance and agreement be reached by scientists on the use of a , a 1 -dipyridyl as a field test to determine the presence of ferrous iron. This is needed in order to make decisions related to the presence of aquic conditions.

8. Data from Mississippi points out that 80 percent of the seasonal variability in soil moisture contents occurs in the upper 20 inches of the soil. The critical depth for determining the presence of aquic conditions is 16-20 inches in Vertisols. It is recommended that this depth be reconsidered.

9. It is recommended that a standardized method be developed for the determination of aquic conditions in Vertisols. This should include how, when and where to make the determination.

ACTION ITEMS

1. The official type location of the Sharkey series will be moved, as had been planned, from West Feliciana Parish, LA to Madison Parish, LA. The series will be reclassified as very-fine, smectitic, thermic Chromic Epiaquerts. The MLRA Leader, Soil Survey Region 16 will be responsible for initiating this action. The official series description will be revised and circulated to the MLRA 131 Board of Directors and others for review and comment by February 28, 1997.

2. A MLRA 131 Board of Directors teleconference will be planned for March 26, 1997 to review comments and discuss other items related to re-classification of the Sharkey series. The MLRA Leader, Soil Survey Region 16 will be responsible for organizing the teleconference and notifying the Board of Directors.

3. Explore the feasibility of re-activating and defining the Dowling Series.

INTRODUCTION

A Sharkey soils study was conducted January 6-10, 1997 in response to a request from the Mississippi Delta Council to re-evaluate the taxonomic classification and hydric status of Sharkey soils in Mississippi. This request was based on research recently published by Dr. David Pettry, Professor and Soil Scientist, Mississippi State University (Pettry and Switzer,1996).

In response to this request, a team was formed to study Sharkey soils in Arkansas, Louisiana, and Mississippi. The NRCS was represented by soil scientists of Arkansas, Louisiana, Mississippi, Kentucky, and Tennessee; the Wetlands Science Institute; the Mississippi Delta Wetlands Team; and the National Soil Survey Center. State Agriculture Experiment Stations were represented by NCSS cooperators from the University of Arkansas, Louisiana State University Agricultural Center, and Mississippi State University. The U.S. Army Corps of Engineers was represented by a soil scientist from the Waterways Experiment Station, Vicksburg, MS, and an environmental specialist from the Vicksburg District. Two retired NRCS soil scientists that have extensive experience with Vertisols and hydric soils also participated in the study. The Leader for MLRA Soil Survey Region 16 served as the team leader and coordinated development of the study report. See Appendix A for a complete list of participants.

GOAL AND OBJECTIVES

The team agreed that the following goal and objectives would be used for this study:

Goal

Determine the proper taxonomic classification and hydric status of Sharkey soils based on the best available technical information.

Objectives:

1. Review the history of the Sharkey series and issues related to taxonomic classification and hydric status.

2. Review the purpose for the Hydric Soils of the United States and Field Indicators of Hydric Soils in the United States publications to understand how they are used to make wetland determinations and delineations.

3. Present and discuss available research data and other information that can be used to determine the taxonomic classification and hydric status of Sharkey soils.

4. Study Sharkey soils in the field on different landscape settings to test hydric soil indicators and to discuss relationships between landscapes and hydrology.

5. Develop a list of remaining problems/issues that need to be addressed to reach a decision on the proper taxonomic classification and hydric status of Sharkey soils.

6. Develop a list of action items to address remaining problems/issues.

HISTORY OF THE SHARKEY SERIES

The Sharkey series is about as old as the soil survey program in the United States. The series was established in Yazoo County, Mississippi, in 1901. Sharkey soils have been mapped throughout the Lower Mississippi Valley.

The Southern Mississippi Valley Alluvium Major Land Resource Area (MLRA 131) covers the area from Cairo, Illinois to the coastal marsh in southern Louisiana (USDA Soil Conservation Service, 1981). Approximately 4.2 million acres of Sharkey soils have been correlated. An approximate acreage by state is as follows: Louisiana-1.80 million; Arkansas-1.04 million; Mississippi-0.85 million; Missouri-0.43 million; Tennessee-0.07 million and Kentucky-0.01 million.

The series type location was moved to West Feliciana Parish, Louisiana in the mid-1960’s, when Soil Taxonomy was adopted. Recently, Louisiana has proposed moving the series type location to Madison Parish, in northern Louisiana. Louisiana is in the process of moving the boundary between the thermic-hyperthermic temperature regimes to just north of Baton Rouge, Louisiana. The current Sharkey series type location is located very near the boundary. Moving the type location to Madison Parish would place the reference pedon nearer the middle of Sharkey’s geographic range. It should be noted that moving the thermic-hyperthermic line north will result in a substantial reduction in total acres of the Sharkey series. A new series has been proposed for Sharkey’s hyperthermic counterpart.

TAXONOMIC CLASSIFICATION

With the adoption of Soil Taxonomy (Soil Survey Staff, 1975), the wet, clayey, alluvial soils of the lower Mississippi Valley were thought to be Inceptisols intergrading toward Vertisols. Sharkey soils were classified as very-fine, montmorillonitic, nonacid, thermic Vertic Haplaquepts. Studies of Sharkey and other very-fine textured alluvial soils in Arkansas, Louisiana and Mississippi, by the NRCS and cooperators, have concluded that the majority of these soils should be classified Vertisols (USDA Soil Conservation Service, 1986, Pettry and Switzer, 1996).

A number of issues related to the classification of Sharkey and other similar soils in the Mississippi River Valley remain unresolved. The study team was in agreement that Sharkey soils should be classified as Vertisols, but a consensus could not be reached on the classification at the suborder, great group and subgroup levels. Louisiana has proposed that Sharkey soils be re-classified as very-fine, smectitic, thermic Chromic Epiaquerts based on the latest edition of Keys To Soil Taxonomy (Soil Survey Staff, 1996).

The central concept of Vertisols is that of fine and very fine textured soils, with deep wide cracks at some time during the year and intersecting slickensides. Vertisols are separated at the suborder level by moisture regimes. Prior to 1992, only udic and drier moisture regimes were recognized in Keys to Soil Taxonomy (Soil Survey Staff, 1990). In 1992, the Vertisol order was rewritten following recommendations of the International Committee On The Classification of Vertisols (ICOMERT). With this revision, "wet" Vertisols were recognized and an aquic suborder was introduced into the Keys to Soil Taxonomy (Soil Survey Staff, 1992).

Data presented to the study team from Mississippi and Louisiana would tend to support both an aquert and udert classification (Pettry and Switzer, 1996, Hudnall and Patterson, 1997). Classification at the suborder level hinges on whether these soils have "aquic conditions", or are artificially drained as required by the current Keys to Soil Taxonomy to class as aquerts. The term aquic conditions was introduced by the International Committee on Aquic Moisture Regime (ICOMAQ) and adopted by Soil Taxonomy in 1992. To have aquic conditions, three properties must be present: (1) saturation, (2) reduction, and (3) redoximorphic features. Artificial drainage is defined, as the removal of free water from soils having aquic conditions by surface mounding, ditches, or subsurface tiles to the extent that watertable levels are changed significantly in connection with specific types of land use (Soil Survey Staff, 1996).

The determination of aquic conditions in Sharkey soils (Vertisols) has proven to be difficult, time consuming, expensive, and labor intensive. A minimum of three years of field monitoring is generally required to get meaningful numbers, but this is not specified in Soil Taxonomy. The field determination of saturation and reduction has raised the most questions. Keys To Soil Taxonomy (Soil Survey Staff, 1996) recommends using piezometers to make the saturation determination, but questions remain as to the accuracy of this method. Does water in piezometers or wells equate to saturation, or to by-pass flow as some researchers contend?

A reliable field method to determine the degree of reduction in soils is by the direct measurement of oxidation-reduction potentials using platinum electrodes, again, an expensive, time consuming, labor intensive method. Keys to Soil Taxonomy suggests using a , a 1 -dipyridyl ( Childs, 1981) as a simple field test to determine the presence of ferrous iron. It has been shown repeatedly that under ideal conditions a , a 1 -dipyridyl will show the presence of minute quantities of reduced iron. On the field tour, each site was tested with a , a 1 -dipyridyl to detect the presence of reduced iron. Some positive reactions were obtained, but none in the 40-50 cm zone as required by the Keys to Soil Taxonomy to meet the aquic conditions requirement of aquerts. Most positive reactions were at micro-sites, or around live roots, at depths of less than 25 cm and usually under standing water. It should be noted that the field tour took place the second week of January when water tables should be at, or near their maximums. From a classification standpoint, the usefulness of a , a 1 -dipyridyl as a dependable field test to determine the presence of aquic conditions is questionable, since a negative reaction does not mean that reduction (aquic conditions) is always absent, but only that the right combination of conditions (saturation, microorganisms, food, ferric iron, etc.) were not all present, or that the soil was in an oxidizing phase when tested.

Another problem area is artificial drainage in these soils. There is general agreement that cultivated areas with surface drainage systems installed are artificially drained. But from a broader perspective, has the construction of levees along almost the entire length of the Mississippi River in the lower part of the valley; the installation of an intricate network of drainage ditches, land smoothing, leveling and shaping affected the natural drainage of the entire valley? Are all soils in the valley artificially drained, or only the cultivated areas? Is the understory plant communities (abundance of Poison Ivy) in natural areas beginning to show the effects of this manipulation on the hydrology? Should all Sharkey and similar soils be considered artificially drained and thus aquerts?

Monitoring data from instrumented sites in Louisiana suggests that Sharkey and similar soils (Newlight) have episaturation (Hudnall and Patterson, 1997). Keys To Soil Taxonomy, (Soil Survey Staff, 1996) defines episaturation as saturated with water in one or more layers within 200 cm of the mineral soil surface and also has one or more unsaturated layers, with an upper boundary above 200 cm depth, below the saturated layer. Water ponds on the surface of Sharkey soils on level to concave, native landscapes and saturates the upper few centimeters. Water perches on plow pans in cultivated areas, both are episaturation, but neither satisfies the saturation requirement for aquic conditions in Vertisols.

At the subgroup level of classification, another problem exists. The Sharkey Official Series Description (7/92) allows hues of 10YR or 5Y, values of 4 to 6, and chromas of 1 or 2 in the range of characteristics of the B horizon, between depths of 25 and 75 cm. With the revision of the Vertisol order and the introduction of Epiaquerts and Endoaquerts great groups, this allows both Aeric and Chromic subgroups within the range of the Sharkey series. Soils with colors values of 4 or 5 and chroma 2 would be Aeric and the remainder would be Chromic.

A number of taxonomic classes have been included in Sharkey map units over the last 90+ years of mapping. These soils have been mapped on a number of geomorphic surfaces. A comparison of tour stops with Saucier’s (1994) maps indicate Sharkey has been mapped in backswamps, on point bars, on several different meander belts and on Pleistocene terraces. Even though all of these surfaces have been veneered with fine-grained, alluvial sediments, it shows that Sharkey has been mapped on a number of geomorphic highs and lows. All of the Mississippi sites were on Pleistocene terraces and the Louisiana sites were in backswamps and meander belts (Saucier, 1994). Could this explain the differences in piezometer data between the two states?

Elevations range from about 30 feet in southern Louisiana to about 250 feet in southern Missouri and Tennessee. Local landforms include lows and highs, both micro and macro, low convex ridges and concave swales and drainage channels. Chromic Epiaquerts occur in the bowls, or micro-lows in level to nearly level units and in concave swales in undulating units. Aeric Epiaquerts occur on micro-highs, in level to nearly level units, on lower sideslopes, in undulating and convex gently sloping units. Aquic Hapluderts, Oxyaquic Hapluderts and Chromic Hapluderts occur on convex ridges and Epiaquents, Endoaquents, Hydraquent, Epiaquepts, Endoaqepts, Humaquepts and possibly other soils occur in concave swales and old drainage channels that remain wet most of the year.

HYDRIC STATUS OF THE SHARKEY SERIES

The Sharkey series is presently listed in Hydric Soils of the United States (USDA Soil Conservation Service, 1991) (hereafter, referred to as the national hydric soils list.) based on saturation, ponding, and/or flooding. County/Parish hydric soils lists include Sharkey mapping units when they occur in County/Parish soil surveys. In general, the public does not have a good understanding of the hydric soils lists and their proper use for identifying hydric soil. There is also a limited knowledge of the field indicators of hydric soils and how they are used to identify and delineate hydric soils. Therefore, the team discussed how the national hydric soils list and the field indicators listed in Field Indicators of Hydric Soils in the United States (USDA Natural Resources Conservation Service, 1996) were developed, and how they are used as tools for identifying hydric soils. The following points were emphasized:

1. The national hydric soils list was created by computer using criteria developed by the National Technical Committee for Hydric Soils. The hydric soils criteria was compared with the estimated soil properties in the national soils data base to determine the probability of a soil being hydric and to create the national list of hydric soils. Presence or absence of a soil on the national list does not mean the soil is hydric or non-hydric.
   

2. Hydric soils lists are only interpretative groupings and, like all soil survey interpretations, must be confirmed by on-site investigations. These lists are intended to be used as a tool to aid in identifying and delineating areas of hydric soils. They were not intended for making off-site delineations of hydric soils. Because of the confusion caused by the national hydric soils list, it was generally agreed that the list should no longer be maintained, or published.
   

3. The field indicators listed in Field Indicators of Hydric Soils in the United States (USDA Natural Resources Conservation Service, 1996) were developed by soil scientists of the Natural Resources Conservation Service in cooperation with the U.S. Fish and Wildlife Service, the U.S. Army Corps of Engineers, the Environmental Protection Agency, and various state and local agencies, and universities. The National Technical Committee for Hydric Soils has recognized thirty-six indicators. The indicators were developed predominantly by correlating soil redoximorphic features to wetland boundaries as identified and delineated by wetland ecologists. Little research has been done to correlate the indicators to saturated soil conditions. It was emphasized that this correlation needs to be made to support the definition and concept of hydric soils.
   

4. Field indicators must be used on-site to delineate hydric soils. Presence of one of these field indicators means that a hydric soil is present. Absence of an indicator does not necessarily mean that the soil is non-hydric. Absence does suggest (if wetland vegetation is present and/or wetland hydrology is suspected) that the morphology should be studied in more detail. The list of indicators is considered to be dynamic; changes and additions are anticipated annually.

Field indicators were used at twelve of the fourteen tour stops to determine the hydric status of the soil. See section titled Sharkey Soils Tour for all observations recorded at each stop. In summary, soils at six of the fourteen tour stops were hydric (three of these sites were in flooded phases of Sharkey), six sites were non-hydric (three of these sites were cultivated and artificially drained) and the hydric status was not determined at two stops. This verifies that within the present concept of the Sharkey series, both hydric and non-hydric components are present. This is true of many soil series on the hydric lists, and emphasizes why on-site visits using field indicators are required for identifying and delineating hydric soils. It should also be noted that artificial drainage and agricultural systems were not considered in the development and testing of the indicators.

The definition of hydric soils (Federal Register, July 13, 1994) implies that once hydric always hydric. Six of twelve stops on the tour were not hydric based on the indicators. Is this because of man’s manipulation of the hydrology in the valley?

As a result of this study, a new field indicator was developed for testing in order to make delineation and identification of hydric soils easier and more consistent in Land Resource Region (LRR) O. The following field indicator will be thoroughly tested before it is recommended for adoption:

TF11. Delta Depleted. For testing in LRR O. A layer at least 15 cm (6 in.) thick starting within the upper 25 cm (10 in.) of the mineral soil that has in 60% or more of the volume either:

1. Matrix value 5 or more and chroma 1 or less, or

2. Matrix value 6 or more and chroma 2 or less, or

3. Matrix value 4 and chroma 1 or less and 5% or more prominent redox concentrations as soft masses or pore linings.

Delta Depleted User Notes: This indicator was developed for use in Mississippi River Delta Vertisols (specifically for the Sharkey Series); however, it is applicable to all soils in LRR O. Rises, knolls, and the micro-highs in gilgai Vertisols normally lack this indicator. Redox concentrations that are continuous with diffuse boundaries reflect current hydrology and redox concentrations that are broken and discontinuous with abrupt boundaries reflect relict hydrology. Use of 10X to 15X magnification aids in the identification. E horizons of other soils in LRR O may be naturally low in iron and thereby have high matrix value and low matrix chroma; therefore, they are required to have redox concentrations regardless of value and chroma.

Use of indicator TF11 (Delta Depleted) would eliminate the need for using Indicator F3 (Depleted Matrix). Therefore, if this indicator is approved for use, the following additions would be made to Indicator F3 (additions are underlined):

F3. Depleted Matrix. For Use in all LRRs except ) O, W, X, and Y.

Depleted Matrix User Notes: Redox concentrations that are continuous with diffuse boundaries reflect current hydrology and redox concentrations that are broken and discontinuous with abrupt boundaries reflect relict hydrology. Use of 10X to 15X magnification aids in the identification.

SHARKEY SOILS TOUR 

The study team spent three days in the field studying Sharkey and similar soils. A total of fourteen sites were visited. Two of the fourteen were impromptu stops and two of the planned stops were not made due to the lack of time. Six sites were located in central and northern Louisiana; two sites were in southern Arkansas and six sites were in central Mississippi (See Figure 2, Sharkey Field Tour Map). The taxonomic classification and the hydric status was determined at each site. A brief vegetation survey was made along with tests for reduction with a , a 1 -dipyridyl. The geomorphic setting was also determined at each site.

Tuesday, January 7, 1997

STOP 1. Current Sharkey type location.

Location: West Feliciana Parish, Louisiana, Louisiana State Penitentiary, Angola. Latitude: 30-56-45.5 N Longitude: 91-35-45.02 W
Elevation: 42 feet by GPS; 44 feet estimated from topo quad.
Geomorphology: Site located on westward migrating point bar within Stage 1, or the modern meander belt of the Mississippi River, Hpm1, (Saucier, 1994). Area protected by levee. Flooded annually prior to levee construction.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: NO. Upper 25 cm had 10YR 4/2 matrix color with 15-20% 10YR 5/4 redox concentrations in six of seven areas tested. Under 10X magnification, the redox concentrations had abrupt boundaries; were broken and discontinuous on ped surfaces and pore linings and therefore considered relict. No field indicators were present.
Vegetation: Cultivated-pasture
Remarks: Site is artificially drained. A surface drainage system was in place. A slightly lower surface was present between the site and river. Access to this site is limited, due to being on prison property. Positive reactions with a , a 1 -dipyridyl in faunal macropore and in upper 25 cm near drainage ditch.

STOP 2. Sharkey clay, frequently flooded

Location: Concordia Parish, Louisiana; Red River Wildlife Management Area.
    Bill Patterson research site-(RR-SF-5).
    Latitude: 31-15-16.62 N Longitude: 91-46-35.08 W
Elevation: 39 feet (Est. from topo quad.)
Geomorphology: The site is near the western edge of a topographic low known as the Dismal Swamp Lowland, which is a flood basin at the confluence of the Black, Red and Mississippi Rivers. Site within Cocodrie Meander Belt of Stage 3, Hpm3, of the Mississippi system (Saucier, 1994). Natural levee deposits flank the Red River to the southwest and dip toward the site. Regional dip is to the southeast toward the center of the basin. Backswamp deposits, which veneer the site, may be from either the Red River or the Mississippi River or both. An artificial levee exists on the north bank of the Red River. This levee prevents flooding on the backside of the Mississippi levee. At the southern end of the Dismal Swamp Lowlands the Mississippi River initiated a diversion channel into the Red River and the Atchafayala Basin. The diversion channel is now controlled, but not prevented, by several Corps of Engineer structures.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: YES; Upper 25 cm had 10YR 5/1 matrix color with 10YR 5/6 & 5/8 redox concentrations. Had field indicator F3 present. Wetland
Vegetation: Wooded-The plant community was dominated by obligate and facultative wet species. The presence of poison ivy may indicates a recent drying trend, however.
Remarks: Instrumented site, See Hudnall and Patterson (1997) for complete data. Site ponded in some areas. Positive reaction with a , a 1 -dipyridyl in scattered spots near surface. A 1.8 m hole was bored in a micro-high, no water enter hole while study team were there.

STOP 3. Sharkey clay, occasional flooded

Location: Concordia Parish, Louisiana; Red River Wildlife Management Area.
     Bill Patterson research site-(RR-SO-5).
     Latitude: ND Longitude: ND
Elevation: 40 ft. (Est. from topo quad.)
Geomorphology: This site is also in the Cocodrie Meander Belt mapped Hpm3 by Saucier (1994) A distinct point bar occurs to the north in section 31. If a ridge and channel pattern exists at the site, it is veneered by fine-grained backswamp sediments probably from the Red River.
Taxonomic Classification: Very-fine, smectitic, thermic Aeric Epiaquerts
Hydric: YES. The site had 10YR 5/1 matrix color with 10YR 5/6 & 5/8 redox concentrations below Red River overwash at 5 inches. Had field indicator F3 present. Wetland
Vegetation: Wooded-The plant community was dominated by obligate and facultative wet species. The presence of poison ivy may indicate a recent drying trend, however.
Remarks: Instrumented site, See Hudnall and Patterson (1997) for complete data. No reaction with a , a 1 -dipyridyl.

Wednesday, January 8, 1997

STOP 4. Tensas Wildlife Management Area; Newlight type location.

Location: Tensas Parish, Louisiana
     Latitude: 32-07-02 N Longitude: 91-26-25 W
Elevation: ND
Geomorphology: The site is in a backswamp, Hb, as designated by Saucier (1994), between the Tensas Meander Belt of Stage 4 of the Mississippi River on the east and Joe’s Bayou Meander Belt of Stage 4 of the Arkansas River to the west. The Tensas River flows in the former Mississippi channel of the Stage 4 meander belt from west of Tallulah to Newlight. Just west of Newlight the Tensas breeches the levee of the Meander Belt and enters the backswamp. The former Arkansas River channel is occupied by Joe’s Bayou and south of Delhi, LA by Bayou Macon. Although designated as a backswamp, the local controlling stream, the Tensas River is entrenched. Base level of the Tensas River is likely lower than the streams that constructed the backswamp. In addition, the secondary streams (Lick Bayou, Leading Bayou and Big Roaring Bayou) that parallel the meander belts are also entrenched. Streams such as Lick Bayou, Leading Bayou and Big Roaring Bayou appear to have formed as distributary channels from both the Arkansas and Mississippi Rivers.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: YES. The site had 10YR 4/1 matrix color with 10YR 5/6 redox concentrations within 25 cm. Had field indicator F3 present. Marginal wetland.
Vegetation: Wooded-The plant community is dominated facultative wet species in all strata. Hydrology indicators not apparent.
Remarks: This site is instrumented and currently being monitored by Bill Boyd, NRCS, Louisiana.

STOP 5. (Impromptu stop) Tensas Wildlife Management Area; Newlight sample site.

Location: Tensas Parish, Louisiana
     Latitude: 32-07-02.49 N Longitude: 91-28-25.32 W
Elevation: 66 ft. (Est. from topo quad.)
Geomorphology: The general geomorphic setting is the same as stop 4. This site, however, is adjacent to an entrenched channel (Cross Bayou). The entrenchment may have altered the local hydrology; the water table has been lowered.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: Not Determined.
Vegetation: Not Determined.
Remarks: Large excavated pit, near local drain. Drain incised 4-5 meters-natural levee of local drain? Sample site-Micro-low-S96LA-107-6; Micro-high-S96LA-107-7

STOP 6. Proposed new Sharkey type location.

Location: Madison Parish, Louisiana
     Latitude: 32-26-18.51 N Longitude: 91-09-55.64 W
Elevation: 81 ft. (Est. from topo quad.)
Geomorphology: This site is in a backswamp, Hb, (Saucier, 1994) unit between the two Mississippi River meander belts; the Tensas belt of stage 4 to the west and the Walnut Bayou meander belt of stage 2 to the east.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: NO. The site had 10YR 4/2 matrix color with 10YR 4/4 redox concentrations in upper 25 cm. Under 10X magnification, the redox concentrations had abrupt boundaries; were broken and discontinuous on ped surfaces and pore linings and therefore considered relict. Had 10YR 4/1 matrix colors below 25 cm. F3 indicator below 25 cm.
Vegetation: Cultivated
Remarks: This site is instrumented and currently being monitored by Bill Boyd. Surface drainage system in place-Artificially drained. See Hudnall and Patterson (1997) for data.

STOP 7. Sharkey clay

Location: Chicot County, Arkansas
     Latitude: 33-15-24 N Longitude: 91-15-04 W
Elevation: 119 ft.
Geomorphology: Saucier (1994) maps this site in the backswamp (Hb) adjacent to the modern meander belt (Hpm1) of the Mississippi River.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: NO. Site had 10YR 4/2, 4/3 & 4/4 matrix colors with 10% faint to distinct 10YR 4/1 redox depletions. No field indicators present.
Vegetation: Cultivated
Remarks: Stop 4 on the 1986 Sharkey study. Surface drainage system in place. Artificially drained.

STOP 8. Sharkey clay

Location: Chicot County, Arkansas
     Latitude: 32-22-46 N Longitude: 91-18-20 W
Elevation: 125 ft.
Geomorphology: Mapped as an Early Wisconsin valley train deposit (Pve1) by Saucier (1994), but should be covered with loess. The surficial, fine grained sediments, however, are overbank deposits that onlap the Early Wisconsin surface, if it is present. For our purposes (soil survey) the surficial sediments and age of the surface are more important than the subsurface material. This area is a backswamp or distal backslope of a levee, and likely the same age as the adjacent stage 1 meander belt.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: Not determined. Too dark (failing sunlight) to read colors. The 1986 description had 10YR 4/1 matrix color with distinct to prominent redox concentrations in the upper 25 cm. If the description was confirmed, then soil would be hydric. Hydrology questionable for wetland.
Vegetation: Wooded-Area undulating with highs and lows. Lows dominated by obligate and facultative wet species. Highs dominated by facultative and facultative upland species.
Remarks: Stop 5 of 1986 Sharkey was in adjacent pasture.

Thursday, January 9, 1997

STOP 9. Sharkey clay

Location: Sharkey County, Mississippi
     Latitude: 33-10-27 N Longitude: 90-47-40 W
Elevation: 100 ft. (Est. from topo quad.)
Geomorphology: This site is in a backswamp (Hb) area adjacent to the stage 3 meander belt (Hpm3) of the Mississippi River (Saucier, 1994).
Taxonomic Classification: very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: YES. Site had 10YR 4/1 matrix color with redox concentrations. Field Indicator F3 present.
Vegetation: Cultivated-soybeans last crop
Remarks: Surface drainage system in place, site artificially drained

STOP 10. Sharkey clay

Location: Washington County, Mississippi, Leroy Percy State Park
     Latitude: ND Longitude: ND
Elevation: 110 ft. (Est. from topo quad.)
Geomorphology: The site is on a Late Wisconsin Terrace (Pvl1) as mapped by Saucier (1994). The instrumentation is on a minor topographic high. The soil map of the area shows an anastomosing network of shallow surface drainageways. The most likely origin of these drains is as flood channels cut during large magnitude floods.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: NO. Site had 10YR 4/2 matrix with 10% faint 10YR 4/1 redox depletions. No field indicators present. Nearby depression had 10YR 4/1 to 5/1 matrix colors with prominent redox concentrations which is hydric.
Vegetation: Wooded-overstory dominated by obligate and facultative wet species indicating a fairly wet condition, however midstory and understory is dominated by facultative and facultative upland species indicating a much drier condition.
Remarks: Instrumented site. See Pettry and Switzer (1996) for complete data.

STOP 11. Sharkey clay

Location: Washington County, Mississippi, Leroy Percy State Park
     Latitude: ND Longitude: ND
Elevation: 108 ft. (Est. from topo quad.)
Geomorphology: This site is on a minor ridge of an abandoned point bar, mapped Hps by Saucier (1994) produced by the secondary drainage systems.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: NO. Site had 10YR 4/2 matrix color with distinct redox concentrations. Under 10X magnification, the redox concentrations had abrupt boundaries; were broken and discontinuous on ped surfaces and pore linings and therefore considered relict. No field indicators present.
Vegetation: Wooded-Overstory dominated by obligate and facultative wet species indicating a fairly wet condition, however midstory and understory is dominated by facultative and facultative upland species indicating a much drier condition.
Remarks: Instrumented site. See Pettry and Switzer (1996) for complete data.

STOP 12. Impromptu stop-cotton field

Location: Washington County, Mississippi, Adjacent to Leroy Percy State Park
     Latitude: ND Longitude: ND
Elevation: 105 ft. (Est. from topo quad.)
Geomorphology: The site is on a Late Wisconsin Terrace, Pvl1 as mapped by Saucier (1994). The soil map shows that this area also contains an interconnected network of surface drains. Origin of the drains is the same as described for stop 11 above, flood channels cut during large magnitude flood events.
Taxonomic Classification: Was not studied in enough detail to determine.
Hydric: NO. Site had 10YR 4/2 and 4/3 matrix colors in upper 25 cm with few distinct redox concentrations. Under 10X magnification, the redox concentrations had abrupt boundaries; were broken and discontinuous on ped surfaces and pore linings and therefore considered relict. No field indicators present.
Vegetation: Cultivated-cotton last crop
Remarks:

STOP 13. CRP field, study site to determine impact of red fire ants on Mississippi soils.

Location: Washington County, Mississippi, Delta States Research Station, Stoneville
     Latitude: ND Longitude: ND
Elevation: 120 ft. (Est. from topo quad.)
Geomorphology: Site on Late Wisconsin Terrace, Pvl1, (Saucier 1994) with interconnecting surface drains.
Taxonomic Classification: very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: YES. The site had 10YR 4/1 matrix colors with prominent 10YR 5/6 redox concentration in upper 25 cm. Had field Indicator F3 present.
Vegetation: Abandoned cropland-CRP
Remarks: Field has been planted with hardwoods. Shallow drain near site-Pettry says does not dry out and crack. Positive reactions with a , a 1 -dipyridyl.

STOP 14. Sharkey clay

Location: Washington County, Mississippi, Delta States Research Station, Stoneville
     Latitude: ND Longitude: ND
Elevation: 120 ft. (Est. from topo quad.)
Geomorphology: Site on Late Wisconsin Terrace, Pvl1, ( Saucier 1994) with interconnecting surface drains.
Taxonomic Classification: Very-fine, smectitic, thermic Chromic Epiaquerts
Hydric: YES. Site had 10YR 4/1 matrix color with prominent 10YR 5/6 redox concentrations. Had field indicator F3 present.
Vegetation: Wooded-overstory dominated by obligate and facultative wet species indicating a fairly wet condition, however midstory and understory is dominated by facultative and facultative upland species indicating area has been drained and no longer has wetland hydrology.
Remarks: Instrumented site. See Pettry and Switzer (1996) for complete data. Trees have major ice damage.

REVIEW OF RESEARCH DATA

Data from instrumented sites in Louisiana tends to support a very-fine, smectitic, thermic Chromic Epiaquert taxonomic classification for the Sharkey series (Hudnall and Patterson 1997). Their data indicates that aquic conditions are present at most sites. Piezometer data, with the exception of RR-SO-3, indicates that saturation occurs at the critical depth during most years. Redox potential data at most sites leans toward reducing conditions at least for short periods during most years.

Data from instrumented sites in Mississippi tends to support a very-fine, smectitic, thermic Chromic Hapluderts (sites 1,3,4) taxonomic classification for the Sharkey series (Pettry and Switzer 1996). Their data indicates an absence of aquic conditions. Well data failed to show the presence of free water in most of these soils. Tests with a , a 1 -dipyridyl failed to show the presence of ferrous iron.

Differences in methodology used by these researchers makes the comparison of actual data difficult. This points out the need for a standardized method to determine saturation and reduction in these soils.

SUMMARY OF CONCLUSIONS

1. The presence or absence of a soil on the hydric soils lists is not conclusive that the soil is hydric or non-hydric. On-site visits using approved field indicators of hydric soils must be used to identify and delineate hydric soils.

2. The field study verified that there is a hydric component and a non-hydric component within the Sharkey Series. This is true of many soils on the hydric lists, and emphases why on-site visits using approved field indicators for hydric soils are required to identify and delineate the hydric components of soils. The Sharkey series should remain on the national hydric soils list. However, because of the confusion caused by the list, it was generally agreed that the list should no longer be maintained, or published.

3. Public understanding is lacking related to the proper use of the hydric soils lists as an off-site tool for identifying potential areas of hydric soils. There is also a limited knowledge of field indicators of hydric soils and the requirement to use them on-site to identify and delineate hydric soils.

4. The taxonomic classification of the Sharkey series should be changed from Inceptisols to Vertisols, but unresolved issues remain related to classification below the order level. These unresolved classification issues do not affect the hydric status of Sharkey soils since taxonomic classification criteria, and hydric soils criteria are not the same.

5. Based on Keys To Soil Taxonomy, Seventh Edition, 1996, there are other taxonomic classes within the present concept of the Sharkey series. This is true for other soil series in MLRA 131, and supports the need for soil survey updates under the MLRA soil survey project concept.

6. There are unresolved questions related to measuring saturation and reduction in Vertisols in order to address taxonomic classification issues. Agreement needs to be reached on: 1) a definition of saturation and reduction; 2) procedures for measuring saturation and reduction; 3) when to measure saturation and reduction. Changes to Soil Taxonomy may be necessary

7. The workload related to solving taxonomic classification problems and updating soil surveys in MLRA 131 is enormous. There is an inadequate staff of soil scientists to do the field work and funds are not presently available to support the needed research.

8. The hydric soil indicators were developed predominantly by correlating soil redoximorphic features to wetland boundaries as identified and delineated by wetland ecologists using only non-agricultural sites . Little research has been done to correlate the indicators to saturated soil conditions. This correlation needs to be made to support the definition and concept of hydric soils.

RECOMMENDATIONS

1. It is recommended that Sharkey soils remain on the national hydric soils list. However, because of the confusion caused by the list, it was generally agreed that the list should no longer be maintained, or published.

2. It is recommended that the Sharkey series not be split into different series based solely on the fact that the present concept of the series includes hydric and non-hydric components. We need to emphasize helping people understand that criteria for taxonomic classification, upon which soil surveys are based, are not the same as criteria for hydric soils.

3. It is recommended that all map units of Sharkey soils be placed on the appropriate local hydric soils list with the approximate percentage of hydric and non hydric components.

4. It is recommended that all wetland scientists in government service and in the private sector begin immediately testing field indicator TF11 and provide either negative or positive comments along with supporting documentation.

5. It is recommended that other soils within Land Resource Region O that have properties similar to Sharkey and occur on similar landscapes be studied to determine if they also have hydric and non-hydric components.

6. It is recommended that more efforts be made to correlate the field indicators for hydric soils to research studies that measure soil saturation and redox potential. This is to confirm that these indicators reflect soils formed under conditions that develop anaerobic conditions in the upper part, as stated in the hydric soil definition.

7. It is recommended that better guidance and agreement be reached by scientists on the use of a , a 1 -dipyridyl as a field test to determine the presence of ferrous iron. This is needed in order to make decisions related to the presence of aquic conditions.

8. Data from Mississippi points out that 80 percent of the seasonal variability in soil moisture contents occurs in the upper 20 inches of the soil. The critical depth for determining the presence of aquic conditions is 16-20 inches. It is recommended that this depth be reconsidered.

9. It is recommended that a standardized method be developed for the determination of aquic conditions in Vertisols. This should include how, when and where to make the determination.

REMAINING ISSUES 

1. The taxonomic classification of the Sharkey series below the order level.
   

2. The Dowling series was established in Tunica County, Mississippi in 1949. Between 1949 and the mid-1960’s, approximately 460,000 acres of Dowling soils were mapped and correlated in the delta counties of Mississippi. Dowling soils occurred in depressions and old stream channels on the Mississippi River floodplain and had very slow to ponded surface drainage according to the 1949 series description. For some unknown reason, the series became inactive sometime around the time Soil Taxonomy was adopted in 1965.

In the late 1960’s and early 1970’s, interpretation records were developed for soil series. Interpretation records listed the physical properties of the series and made interpretations for various uses. With the development of State Soil Survey Databases, all series had to have interpretation records to develop the manuscript tables for soil survey reports and to make local interpretations for various uses. Since Dowling was inactive and no interpretation record existed for the series, a similar soils’ (Sharkey) interpretations records were substituted for Dowling. This resulted in interpretations being made for Dowling based on Sharkey’s properties. Dowling soils have not been re-correlated to Sharkey in counties where it appears in soil survey reports, only another soils interpretation record has been substituted for Dowling. This has caused some confusion in Mississippi related to the hydric soils issue.

ACTION ITEMS

1. The official type location of the Sharkey series will be moved as had been planned from West Feliciana Parish, LA to Madison Parish, LA and reclassified as very-fine, smectitic, thermic Chromic Epiaquerts. The MLRA Leader, Soil Survey Region 16 will be responsible for initiating this change. The official series description will be revised and circulated to the MLRA 131 Board of Directors and others for review and comment by February 28, 1997.

2. A MLRA 131 Board of Directors teleconference will be planned for March 26, 1997 to review comments and discuss other items related to re-classification of the Sharkey series. The MLRA Leader, Soil Survey Region 16 will be responsible for organizing the teleconference and notifying the Board of Directors.

3. Explore the feasibility of re-activating and defining the Dowling Series.

REFERENCES

• Childs, C. W. 1981. "Field Test For Ferrous Iron And Ferric-Organic Complexes (on exchange sites or in water-soluble forms) In Soils," Aus. J. Soil Res. 19, 175-180.

• Federal Register. July 13, 1994. Changes in Hydric Soils of the United States. Washington, DC.

• Hudnall, W.H. and W.B. Patterson. 1997. Sharkey Field Tour. Louisiana, Mississippi and Arkansas. Agronomy Department, Louisiana Agricultural Experiment Station, Baton Rouge, LA

• Pettry, D.E. and R.E. Switzer. 1996. Sharkey Soils In Mississippi. MAFES. Bul.1057.

• Rutledge, E.M., Guccione, M.J., Markewich, H.W., Wysocki, D.A., and L.B. Ward. 1995. "Loess Stratigraphy of the Lower Mississippi Valley," A Conference on Geology in the Lower Mississippi Valley-Implications for Engineering-The Half Century Since Fisk, 1944, Engineering Geology. In press.

• Saucier, R.T. 1994. Geomorphology and Quaternary Geologic History Of The Lower Mississippi Valley. Vol. I and II, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS

• Soil Survey Staff. 1975. Soil Taxonomy: A Basic System of Soil Classification For Making and Interpreting Soil Surveys. U.S. Department of Agriculture, Soil Conservation Service, Agriculture Handbook 436, U.S. Government Printing Office, Washington, DC.

• 1990. Keys To Soil Taxonomy, Fourth Edition, SMSS Technical Monograph No.6, Blacksburg, Virginia

• 1992. Keys to Soil Taxonomy. SMSS Tech. Monograph No. 19, 5th ed., Pocahontas, Press, Inc., Blacksburg, VA

• 1996. Keys to Soil Taxonomy. Seventh Edition, USDA Natural Resources Conservation Service, U.S. Government Printing Office, Washington, DC

• U.S. Department of Agriculture, Soil Conservation Service 1981. Land Resource Regions and Major Land Resource Areas of the United States. Agriculture Handbook 296, Washington, DC.

• Soil Conservation Service 1986. Sharkey-Alligator Study, Arkansas, Louisiana and Mississippi, unpublished data.

• Soil Conservation Service 1991. Hydric Soils of the United States. Miscellaneous Publication No. 1491, U.S. Government Printing Office, Washington, DC.

• Natural Resources Conservation Service. 1996. Field Indicators of Hydric Soils in the United States. G.W. Hurt, Whited, P.M., and Pringle, R.F. (eds.) USDA, NRCS, Fort Worth, TX

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