NSSH Part 631

Soil Survey Investigations

Definition and Purpose (631.00)

Soil survey investigations are activities that develop and provide reliable new information and understanding about soils, soil relationships, and soil survey methods. Soil survey investigations:

• supplement field information with laboratory and analytical data on the properties and behavior of soil;
• develop field and laboratory methods;
• provide a database of soil information;
• provide concepts, methods, understanding, and predictions for soil survey interpretations and modeling; and
• develop and provide theories and understanding to soil formation and the relationship of soils to genetic and landscape factors.

Policy and Responsibilities (631.01)

(a) Authorization

The Natural Resources Conservation Service (NRCS) has authorization for research in support of soil survey activities. Soil survey researchers of the NRCS coordinate with field, state soils staffs, and state conservationists of NRCS and partners of the National Cooperative Soil Survey (NCSS). Investigations primarily focus on the soils of the United States, Puerto Rico, and trust territories. Researchers working in other countries coordinate with the NRCS International Conservation Division and the USDA Office of International Cooperation Division of the Foreign Agricultural Service.

(b) Investigations

Investigations by the National Soil Survey Center respond to requests from NRCS MLRA or state offices, other branches of the NRCS, and other organizations. The National Soil Survey Center initiates some projects to advance the NCSS program.

(c) National Soil Survey Center Responsibilities

The National Soil Survey Center is responsible for:

• leadership in regional and national research projects for soil surveys,
• leadership in the federal research program in pedology,
• manuals on laboratory procedures,
• training for field investigations, and
• the soil survey laboratory databases.

(d) MLRA Office Responsibilities

The MLRA office is responsible for:

• approval of field soil survey investigations,
• attribute data in the National Soil Information System,
• identifying data voids,
• coordinating work plans with cooperators,
• requesting National Soil Survey Center assistance,
• ensuring complete and accurate pedon descriptions and the index for soil characterization samples and
• updating the classification of pedons in the national index.

(e) Project Leader Responsibilities

The project leader is responsible for:

• complete and accurate pedon descriptions and classification of soils on sampling projects within the project area.

Kinds of Projects (631.02)

(a) Laboratory Characterization Projects

(1) Characterization projects define the morphological, chemical, physical, and mineralogical properties of soils within a major land resource area. The data are included in soil survey reports at the discretion of the MLRA office team leader.

(2) Characterization projects usually include suites of standard laboratory analyses, which are defined in part 631.03 (a).

(3) Laboratory characterization projects require work plans for the major land resource area. Exhibit 631-5 provides an example of a characterization work plan. The work plan identifies pedons and laboratory data that may be published in the soil survey.

(b) Research Projects

(1) Research projects define soil data relationships, soil genetic processes, soil-landscape relationships, soil interpretive applications, or criteria for soil classification. Research projects normally combine field observations and laboratory or special field analyses. Some projects examine existing data to reveal new data relationships or applications.

(2) An outline of the objectives, hypotheses, and methods of study for research projects reduces the complexity and helps report the results to other scientists.

(3) Research projects require work plans. Exhibit 631-3 gives an example of a research project work plan checklist, and Exhibit 631-4 gives an example work plan.

(c) Laboratory Reference Projects

(1) Reference projects answer a single question or at most very few questions, directed at quick analyses such as on particle-size class, base saturation, or mineralogy.

(2) Reference projects require basic documentation, including pedon descriptions, but do not require work plans.

(d) Other Kinds of Projects

Other projects or services include landform and geomorphic studies, ground penetrating radar, other special measurements, extraction of information from the laboratory database, and literature searches.

Liaisons and others at the National Soil Survey Center answer technical questions and help develop plans for a state, major land resource area, or other land area.

The National Soil Survey Center staff cooperates on various projects with visiting scientists, including NRCS soil scientists. Studies by major land resource area, including soil survey updates, are an example.

Listings of existing data for the area of interest are available and should be obtained prior to requesting additional data-gathering projects.

Laboratory Investigation Methods (631.03)

(a) Standard Analyses

Standard laboratory analyses include chemical, physical, and mineralogical analyses for classification of soils within Soil Taxonomy. Analyses also answer specific questions relating to soil survey interpretations and soil performance. The more routine analyses include particle-size, cation exchange capacity, base saturation, organic carbon, pH, calcium carbonate equivalent, salt, bulk density, water retention, and clay mineralogy.

Laboratory analyses follow standards described in Soil Survey Investigations Report No. 42, Soil Survey Laboratory Methods Manual. Only the laboratory data from standard analyses enters the permanent Soil Survey Laboratory Database. Method codes identify the analytical method for these analyses.

(b) Special Analyses

Some chemical, physical, and mineralogical analyses answer specific requests from states for conservation activities or to test new methods. Recurring requested analyses may become standard. Special analyses include published procedures used by other laboratories that have been developed or adapted by the Soil Survey Laboratory.

(c) Soil Sampling and Analysis

(1) A soil horizon is the primary sampling unit. For all characterization projects and some reference projects, all horizons to 2 meters are sampled unless hard bedrock (lithic contact) is at a lesser depth. The project work plan identifies the pedons to be sampled and analyses to be made.

(2) The soil survey project office locates pedons for sampling that represent the soils and conditions of concern. Large excavations facilitate sampling. The sampling team records site data, including geomorphic information, vegetation, land use, and pedon description data before soil sampling begins.

(3) Most laboratory analyses use air-dry bulk samples that are screened through a 2-mm sieve. Bulk samples need to be large enough to represent the proportion of rock fragments up to 20 mm (3/4 in.) in diameter and to provide at least one quart of material less than 2 mm in diameter. Proportions of rock fragments larger than 20 mm (3/4 in.) in diameter are estimated by volume or by a combination of weight and volume in the field. Bulk density and moisture retention determinations require clod samples which preserve the field configuration of pore space. The Soil Survey Laboratory has detailed information on pedon sampling.

(4) The project objectives determine the analyses. The local and laboratory project coordinators jointly refine the objectives. Sampling protocol and standard laboratory analytical methods may be referenced in the Soil Survey Laboratory Methods Manual.

(5) The Soil Survey Laboratory, upon request, provides sampling equipment and supplies, such as bags, tags, shipping documents, saran for coating clods, clod boxes, etc., for sampling soils that are to be sent to the laboratory. The National Soil Survey Center budgets costs for analyses and assistance for projects with NRCS and NCSS cooperators based on available funding and workload requests.

Field Investigation Methods (631.04)

(a) Landscape and Geomorphic Studies

(1) Geomorphic studies use standard geologic methods and concepts of geomorphic surfaces to understand the relations among soils and the various parts of the landscape. Geomorphic surfaces can identify landscape elements that share a common geologic time component and can establish how different landforms and their materials relate to each other.

(2) Field investigations of soil-geomorphic relations require detailed studies of the surficial geology and geomorphology of a small area. In the process, these patterns are related to the occurrence and distribution of soils.

(3) The four phases of a field investigation are: (1) determining the surficial geology, such as deposits and stratigraphy, (2) identifying the geomorphic surfaces to help establish the landscape and time frame, (3) establishing spatial relations through elevation and distance control, and (4) relating soil patterns to geomorphic units.

(4) State Conservationists initiate field investigations with a request for technical assistance to the National Soil Survey Center, as described in Part 631.06. Obtain local assistance through national soil survey cooperators, state geological surveys, and universities.

(b) Ground-Penetrating Radar and Electromagnetic Ground Conductivity Meter

(1) Ground-penetrating radar (GPR) reveals differential transmission, reflectance, and attenuation of the radar signal within soil. It indicates the depth and horizontal continuity of objects, horizons, or layers below the soil surface. Observation depths range from less than a meter in clays to thirty meters in some sands.

(2) Ground-penetrating radar helps to evaluate small-scale patterns of soil variability and estimate the composition of soil map units. It evaluates the continuity of root-restricting layers, and reveals other features and patterns that are important for soil mapping but are not clearly related to surface features.

(3) Several NRCS state offices maintain ground-penetrating radar equipment and operators. The National Soil Survey Center staff applies ground-penetrating radar to characterize soils and soil variability, determine the depths to diagnostic soil horizons, map bedrock surfaces and fractures, profile geomorphic and stratigraphic features, profile organic deposits and estimate peat reserves, and detect buried utilities, hazardous waste containers, and artifacts. The National Soil Survey Center offers this service to the agency and cooperating groups.

(4) Electromagnetic induction estimates the electric conductivity of soil materials at variable depths below the soil surface. The electrical conductivity of soils is influenced by the type and concentration of ions in solution, the amount and type of clays in the soil matrix, the volumetric water content, and the temperature and phase of the soil water.

(5) Electromagnetic induction uses electromagnetic energy to measure the apparent conductivity of earthen materials. Values of apparent conductivity are seldom diagnostic, but lateral and vertical variations in these measurements help to infer changes in soil types and soil properties, depths to contrasting layers and bedrock, and the locations of buried cultural features. Interpretations of the data base on the identification of spatial patterns within data sets.

(6) Several NRCS state offices maintain electromagnetic induction or towed array resistivity devices and operators. The National Soil Survey Center staff applies this technology to characterize soils and soil variability for many purposes. These purposes include precision farming and high intensity soil surveys, assess the distribution of saline and sodium affected soils, locate and map contaminant plumes emanating from waste-holding facilities, filter strips, mine tailing ponds or landfills, locate buried artifacts and areas of disturbed soils, and select sampling or monitoring sites. The Center loans instruments and offers field assistance and training to the agency and cooperating groups.

(c) Other Special Measurements and Instrumentation

The National Soil Survey Center offer other special equipment, such as electrical resistance blocks for water content and water suction, salinity meters, soil moisture and temperature sensors, and various permeameters for special investigations. Global positioning devices help document the locations of measurements. The center also provides simple, noncommercial methods to measure diverse properties, such as clod and crust rupture resistance, the near-surface bulk density of fragile soil materials, and roughness.

Investigations Planning (631.05)

(a) Objectives

Work plans focus the question, identify the resources required, and schedule the necessary steps. Research and full characterization projects require a written work plan because of the complexity and duration of the project; the number and location of participants; the magnitude of time, funds, and other resources required; and the relationships of organizations.

(b) Planning Process

(1) Project initiation

Anyone within the NCSS or even from outside the NCSS may recognize the need and initiate an investigations project. The memorandum of understanding for a project soil survey often initiates projects. The soil survey project office may identify an investigations need as a survey progresses. Review of the laboratory data within the major land resource area may show gaps in information and consequently lead to an investigation project. State, regional, national, or international initiatives may also generate a need for special projects.

(2) Project definition

A cooperative effort by several investigators from more than one agency may provide project objectives and background information. If projects are within a survey area, the project soil scientist and staff draft the objectives, background, and needs of the project.

(3) Scheduling and responsibilities

The person who initiated the investigations usually is responsible for scheduling and arranging for resources that are required to conduct the investigation. This information is outlined in the project work plan. For reference projects, the time and nature of information needed are in letter or oral agreements. For small projects with analyses, the letter of transmittal accompanying the samples includes the necessary information. Send copies of correspondence to appropriate administrators and interested technical people.

(c) Work Plans

Project work plans provide background information about the study area, survey project, scientific issues, resource relationships, or other concerns to identify the scope, objectives, and requirements. Work plans clearly specify the objectives, the needs, and the expected benefits. They assign responsibilities, estimate the resources needed, and outline how the results will be made available and used. Exhibit 631-3 and Exhibit 631-4 show a checklist and example work plan for a research project. Exhibit 631-5 gives an example work plan for a characterization project.

Requesting Assistance (631.06)

Prior to the beginning of each fiscal year (usually by July 10), the National Soil Survey Center requests state conservationists to submit their needs for assistance for the following year. Responses to those requests allow the National Soil Survey Center to allot resources and plan travel. The project work plan is to accompany the submission. Project work plans should be coordinated with cooperators prior to submission. The laboratory returns the work plan to the originator with comments and suggestions before work is begun on the project.

For reference projects, the request for assistance may accompany the samples and confirmed orally or in writing through the liaisons.

All submissions of samples should include a list of the pedons and horizons sampled and pedon descriptions. It is desirable to have a statement of the problem and any time constraints that one may have.

Liaisons for the National Soil Survey Center to the various MLRAs or states and other staff members are available for the discussion, planning, and development of proposals for technical assistance on an informal basis at any time.

Laboratory Databases (631.07)

(a) Soil Survey Laboratory Database

The Soil Survey Laboratory database, located in Lincoln, Nebraska, currently contains data for more than 23,000 pedons from analyses performed at the Soil Survey Laboratory and from the three pre-existing NRCS laboratories (at Riverside, Beltsville, and Lincoln). The laboratory adds data from more than 600 pedons annually. Customers may access the data through the National Soil Characterization Database or CD-ROM. Access to the indexed data through the online database is by state and county, by major land resource area(s), by classes of soil taxonomy, or by several other criteria.

(b) Index of Laboratory Data

(1) The index of laboratory data allows for easy sorting of data available. The index only allows entry of data obtained by standard procedures. The index requires classification by soil series or family and a description of the site and pedon.

(i) For each pedon, the index includes the pedon classification, latitude, longitude, map unit symbol, state, soil survey area, location of the sampled pedon, source of the data, kinds of analyses available, and other information. Exhibit 631-1 illustrates NRCS-SOI-8, Input Form for the Index of Soil Laboratory Data.

(ii) The MLRA office updates the file at any time by sending an updated NRCS-SOI-8 to the Soil Survey Laboratory. The Soil Survey Laboratory assigns the computer record and pedon numbers and maintains the computer files and the index.

(2) Exhibit 631-2 provides instructions for completing the NRCS-SOI-8.

(i) At the time of sampling, the sampling team drafts a soil description. This description including location by latitude, longitude, MLRA, MOIST REGIME, SS AREA and field symbol accompany the soil samples to the laboratory.

(ii) The Soil Survey Laboratory generates several items on the NRCS-SOI-8. These are: REC (01), STAT (02), PED NO (03), LAT (05), LON (06), SOURCE (11), SAMPLED AS (12), FIELD SYMBOL (13), LAB SAMPLE NUMBERS (14), STATE AND LABORATORY (15), SAMPLE (16), SOIL SURVEY SAMPLE NO (17) and all analyses counts (items 39-67), except item 42. Exhibit 631-2 provides an example. For the SOURCE (11), the data are considered unpublished when analyses are initially completed and distributed by the Soil Survey Laboratory. Later, if the data are published, the MLRA office updates the SOURCE (11). The choices for SAMPLE (16) may or may not be circled by the Soil Survey Laboratory because samples on hand may be discarded as a result of insufficient storage space. After the samples are analyzed and data reviewed, the Soil Survey Laboratory sends the data, NRCS-SOI-8, and review comments to the MLRA office.

(iii) The MLRA office completes or assures completion of several items on the NRCS-SOI-8. These are: INIT MO/YR (04); LAT (05); LON (06); CURRNT NAME (07); DATE (08); PUB SYMBOL (09), if applicable; TAX CODE (10); MLRA (18); DATE CLASSIFIED (19); SS AREA (20); MOIST REGIME (21); REFERENCE CITATION (22); TAXONOMY CODES (23); and NOTE (31). The MLRA office returns the NRCS-SOI-8 to the Soil Survey Laboratory within 45 days. If changes are needed, the old data are lined out and the new data are entered above the old in red pen or pencil. The Soil Survey Laboratory enters the information in the Soil Survey Laboratory computer file and returns an updated NRCS-SOI-8 to the MLRA office.

(3) The records in the index may need amending, particularly the classification of the pedon analyzed (23 TAXONOMY CODES) and the date of the classification of the pedon or of any amendment of the classification (19 DATE CLASSIF). Only complete those items on the NRCS-SOI-8 that are to be amended. The MLRA office ensures the accuracy of the updated data, and the Soil Survey Laboratory verifies it.

(i) For changes in soil taxonomy, the MLRA office determines whether the revision affects the classification of pedons in the national index. If classification is affected, the MLRA office submits the necessary changes to the Soil Survey Laboratory for input.

(ii) The Soil Survey Laboratory completes an NRCS-SOI-8 as necessary to amend records already in the index. The laboratory sends these input forms to the MLRA office for review and for approval of the pedon classification. The MLRA office reviews the classification and returns the NRCS-SOI-8 to the Soil Survey Laboratory within 45 days.

(iii) The MLRA office for the state in which the pedon was sampled receives all other proposals for amendments. The MLRA office classifies the pedon, makes any corrections needed on the NRCS-SOI-8, and sends it to the Soil Survey Laboratory.

NRCS-SOI-8 Input Form for the Index of Soil Laboratory Data (Exhibit 631-1)

High resolution image of NRCS-SOI-8 Input form can be found here. (PNG, 948 x 587, 36 KB)

Instructions for Completing the NRCS-SOI-8 Input Form for the Index of Soil Laboratory Data (Exhibit 631-2)

The Soil Survey Laboratory assigns a computer RECORD number to all pedons that are entered in the national index. The Soil Survey Laboratory assigns a unique sequential PEDON NUMBER to identify pedons and to calculate record numbers for their computer files and for the Soil Laboratory Data Index.

To complete the NRCS-SOI-8, print all entries following these instructions:

Item 01 - RECORD. This is assigned by the Soil Survey Laboratory.

Item 02 - STATUS. This indicates the kind of data storage. Circle:

• N, if data are in the Soil Survey Laboratory computer files
• O, if part or all of the data are stored in computer files other than those of the Soil Survey Laboratory
• X, if data storage is not computerized
• F, reserved

Item 03 - PEDON NUMBER. This is a unique sequential number that is entered by the Soil Survey Laboratory. All communications with the Soil Survey Laboratory that concern a pedon must use its reference number.

Item 04 - INITIALS MONTH/YEAR. Enter the initials of the staff member who is responsible for completing the applicable portions of the NRCS-SOI-8 form. Also indicate the month and year of entry; for example, for April 1992, enter "04/92."

Item 05 - LATITUDE. Enter degrees and direction from the equator, and minutes and seconds.

Item 06 - LONGITUDE. Enter degrees and direction from the prime meridian, and minutes and seconds.

Item 07 - CURRENT NAME. Enter the current series name or "SND" (series not designated) for the pedon sampled after any review or any classification using laboratory data. After the series name, if applicable, enter "I" for inclusion if the pedon is not in the name of the map unit listed in item 09.

Item 08 - DATE. Enter the date that the current name was assigned in item 01; for example, for May 1992, enter "05/92."

Item 09 - PUBLICATION SYMBOL. If one has been assigned, enter the publication symbol of the map unit in which the pedon was sampled.

Item 10 - TAXONOMY CODE. Circle the most appropriate code for the pedon ("F" for family classification, "L" for series type location, "R" for the series range, "T" for taxadjunct, "V" for variant, and "S" for slightly outside the range of the series but within the classification of the family.) Use "V" only if the pedon sampled was correlated as a variant. The use of variant has been discontinued and only applies to older correlations. If item 07 is "SND", code "F" must be circled. If "T", "V", or "S" is circled, give a brief explanation in the "NOTES" as to why the pedon is outside the range of the series. The classification of the pedon in the series category should be in accord with the current official soil series description and with the current rules, as of the date in item 08, that are used for identification of taxadjuncts and variants.

Item 11 - SOURCE. Circle the code that identifies the source document for the results of the analyses indexed on this form. If there is more than one source document, the codes should be listed in the following sequence: "I" for SSIR, "M" for published soil survey, "O" for other published source, "T" for thesis, and "U" for unpublished data.

Item 12 - SAMPLED AS. Enter the series name that was assigned to the pedon when it was sampled. If the series name is not known, enter "SND." After the series name, if applicable, enter either "L" for type location, "T" for taxadjunct, "V" for variant, or "P" for proposed series.

Item 13 - FIELD SYMBOL. Enter the field map unit symbol if the publication symbol has not been assigned. Length of entry is limited to five characters.

Item 14 - LABORATORY SAMPLE NUMBERS. Enter the first and last laboratory sample number assigned to the horizons of the pedon by the laboratory that is identified in item 15.

Item 15 - LABORATORY. Enter the Federal Information Processing Standards (FIPS) alphabetic code for the state in which the laboratory that made most of the analyses indexed on this form is located and circle the code that identifies that laboratory. Circle "S" for the former Riverside, Lincoln, or Beltsville NRCS regional soil survey laboratories; "L" for the NRCS Soil Survey Laboratory; "C" for a NRCS state laboratory; "M" for a NRCS soil mechanics laboratory; and "O" for other laboratories. If "O" is circled, then list the name of laboratory in item 22.

Item 16 - SAMPLE. Circle "Y" for yes or "N" for no to indicate whether or not bulk samples are on hand. Circle "U" if this information is unknown.

Item 17 - SOIL SURVEY SAMPLE NUMBER. Enter the Soil Survey Sample Number (SSSN) as it is normally written, for example, S85AA-007-001A. (The letters A-Z are used for satellite pedons). Use the FIPS two-character code for the state and the FIPS three-digit numeric code for the county.

Item 18 - MAJOR LAND RESOURCE AREA (MLRA). Enter the code for the land resource region and major land resource area and, if applicable, the subdivision code of the MLRA. Use the county NATIONAL RESOURCE INVENTORY (NRI) map to obtain the MLRA code.

Item 19 - DATE CLASSIFIED. The person who last classified or amended the classification of the pedon completes this item. Enter the month and year that the pedon was classified using four digits; for example, "12/90." For updating records, such as if the classification of the pedon is changed, enter the current month and year in this item. This item is the date of the most recent review of the classification.

Item 20 - SOIL SURVEY AREA. Enter the soil survey area identification number for the area in which the pedon was sampled.

Item 21 - MOISTURE REGIME. Enter the code for the soil moisture regime as given in Appendix A of the State Soil Survey Database User's Manual.

Item 22 - REFERENCE CITATION. If the data for the pedon are published, enter a reference citation for the source document or thesis indicated in SOURCE (11) using the FIPS alphabetic code for the state and use other abbreviations to restrict entry to 24 characters, including spacing and punctuation. Also circle "P" for published following the citation. The format that uses "SSIR" followed by a space, the number of the volume, a comma, space, a "P," and the page number are mandatory for SSIR's; for example, "SSIR 2, P21." The format exemplified by "SONOMA CO., CA, P178" is preferred for published soil surveys. A suggested format for thesis is exemplified by "DONOVAN, MS-TEX Tech-74." If the source data are unpublished and the letter "O" is circled in item 15, enter the abbreviated name of that laboratory, for example, "BLM, Denver, CO" or "TX A and M, Ag. Exp. Sta," and circle "U" for unpublished following the name.

Item 23 - TAXONOMY CODES. Enter the applicable taxonomic codes for the family classification of the pedon as given in NASIS Metadata 5.0 (http://nasis.nrcs.usda.gov/documents/metadata/5_1/). Always enter a code for frigid, cryic, or pergelic temperature regimes for use in computer searches. For example:

U UD PA PL/04 096 46 __ 18 ___
OR SO GG SGMOD PS MIN PH TEM OTH

Items 24-30 - The family classification of the pedon is generated from the TAXONOMY CODES and printed out here.

Items 39-67 - The analyses counts and subclasses are based on the pedon data in the laboratory files and other laboratory data maintained in state files. If other data are available (including Highway Laboratory test data), enter the actual count of the analyses and subclass, if applicable, or adjust existing index entries to include the additional data. The Soil Survey Laboratory completes this section for all samples analyzed at the Soil Survey Laboratory. The MLRA office is responsible for information for samples analyzed at a laboratory other than the Soil Survey Laboratory.

For more information contact:
Soil Survey Laboratory
National Soil Survey Center

Research Work Plan Checklist (Exhibit 631-3)

1. Statement of Problem

• concise summary
• questions that illustrate problem and should be answered by the study
• operational, such as "need to know in order to" rather than just need to know

2. Justification

• local importance, such as for county
• implications for wider application, such as at State and regional levels
• benefit(s) to the soil survey program

3. Background

• setting, such as climate, geology, landscapes, or soils.
• soil series and their classification
• persons familiar with the problem, such as those in NRCS or at a university.
• specific background work pertaining to the problem, such as fieldwork, reviews, preliminary data gathering

4. Information Needed

• geomorphic assistance
• literature review
• evaluation of existing data
• information to be gathered in present study

5. Actions and Assignments

• projected time table
• project coordinators such as the person in the state whom the National Soil Survey Center staff should contact
• Soil Survey Laboratory assistance needed:
  • analyses suggested, such as specific questions to be answered for each soil and or horizon (complete analyses are not necessarily needed for limited, specific problems)
  • persons involved, including when and for what, and any necessary travel, etc.
• report responsibility
• report review responsibility
• distribution and application of data, such as within state or in other states.

6. Illustrations

• diagrams and illustrations that define study area location, soil-landscape, and stratigraphic relationships.

Example Research Work Plan (Exhibit 631-4)

INVESTIGATION OF THE SOILS IN
THE REGION OF GLACIAL LAKE KASKASKIA
IN MLRAs 113, 114, AND 115

Sam J. Jones
MLRA Project Office
Belleville, IL

The Problem

(a) A significant portion of St. Clair County, and portions of Randolph, Monroe, Washington, Clinton, Bond, Fayette, and Marion Counties (Figure 1) are underlain by glaciofluvial and lacustrine deposits. These deposits can range in age from pre-Illinoian (formerly designated as Kansan or Nebraskan, and now grouped together as middle Pleistocene) to Woodfordian (mid to late Wisconsinan or late Pleistocene) or even to Holocene. The youngest of these deposits related to glacial activity is correlated with the Equality Formation (described by Willman and Frye, 1970). The fluvial deposits in the present flood plain area are correlated with the Cahokia Alluvium.

(b) The younger deposits in Glacial Lake Kaskaskia are part of the Equality Formation. Most of these areas are covered by Peoria Loess, except for the lowermost Woodfordian and possibly the early Holocene terrace level, which appears to have little or no loess cover (Figure 2). Extensive areas of Iva, Weir, Piasa, Herrick, Virden, and other similar soils were mapped on the other terraces along the Kaskaskia River. These soils typically formed in materials considered to be associated with upland positions.

(c) The original field sheets for the St. Clair County soil survey showed mapping units represented by tentative symbols, such as V308 (Alford), V453 (Muren), T16 (Rushville), V47 (Virden), T453B (Muren), and T454A (Iva). "V" was used for variant and "T" for terrace. These symbols were used to suggest differences in stratigraphy that do not traditionally occur in these upland soils. Documentation and correspondence during the survey also supported differences in stratigraphy. These differences were included in the "Formation of the Soils" section of the St. Clair County soil survey (Figure 3) (Wallace, 1978) but not included in the mapping and classification of the soils in the county. One of the main reasons for this exclusion was the emphasis in the 1978 survey on the description and classification of the soils to a depth of only 60 inches.

(d) More recently, the terrace/upland problem has been recognized in adjacent counties. During the recently completed Clinton County soil survey, soils formed in lacustrine deposits were mapped as T46 (Herrick), T47 (Virden), and 474 (Piasa). Soils mapped in mapping units T47 and 474 were eventually classified as a Montgomery taxajunct (a soil developed in lacustrine material), and a new soil series was developed in lieu of terraced-positioned Herrick soil mapped in map unit T46 to recognize the importance of the lacustrine parent material.

(e) Questions have arisen on the impact of these terrace soils and underlying materials on water availability for crops, crop yields, and water quality. The Iva (86 bu/ac), Herrick (89 bu/ac), and Virden (91 bu/ac) upland soils have relatively high corn yields listed in University of Illinois Circular 1156 (Fehrenbacher et al., 1978) compared to the listed yields of the traditional terrace soils, which include Okaw (47 bu/ac) and Hurst (52 bu/ac). Also, the yield on areas on the terrace mapped as Piasa is much higher than that listed for the Piasa (52 bu/ac) that is traditionally mapped as an upland soil. These discrepancies have been brought to light in recent tax appeals to the State Board of Review. Differences in observed yields suggest differences in soils and available moisture for crop growth. These differences also suggest that the clayey substratum of the terrace soils influence the available water and the movement of the water through the soil.

(f) The problem involves not only accurately mapping and classifying the surface soils but also accurately identifying and mapping the underlying materials, which influence the genesis, classification, and management of these soils. The objective of this study is to accurately identify soils, parent materials, and stratigraphy in the Glacial Lake Kaskaskia area. The hypothesis is that soils in the Glacial Lake Kaskaskia area differ from the upland soils, and that this difference is reflected in stratigraphy, physical and chemical soil properties, water status, and crop yields. Studying these soils in detail will provide more accurate interpretations for agricultural and urban uses in the Glacial Lake area and the adjoining upland areas.

Justification

The Kaskaskia River glaciofluvial and lacustrine deposits occur in eight counties. The drainage basin of the Kaskaskia River covers 3,712,640 acres. The importance of the surficial and subsurficial materials in the Kaskaskia River Basin to agriculture and to the ground-water quality of the area is evident. Rapid urban growth is occurring in St. Clair, Randolph, and Monroe Counties, and therefore, more urban and agricultural demands are being made on water that is supplied by the Kaskaskia River Basin. St. Clair County is currently being updated as part of the Major Land Resource Area Soil Survey Update program in Illinois. Not only will the update in St. Clair County benefit from this study, all updates of the other counties within MLRAs 113, 114, and 115 that have glaciofluvial and lacustrine deposits will also benefit. The information gained in this study will improve the credibility of the soil survey by supplying the survey users with more accurate and precise soil maps and interpretations. We will also be gathering soils and geology information at greater depths.

Background

(a) Most of the soils in the study area are the types that occur on uplands. The uplands consist mainly of the Illinoian glacial till plain or glacial outwash plain that is covered by loess. The total thickness of the Peoria Loess and Roxana Silt ranges from 100 feet in the western part of the area to 4 or 5 feet in the eastern part. Soils on the terraces formed in loess less than 60 inches thick overlying clayey material or in the clayey material. There are also extensive areas of alluvial lands and bottomlands that drain to the Kaskaskia River, which, drains into the Mississippi River.

(b) The focus of this study is to determine the boundary between the upland areas, represented primarily by soils formed in loess over glacial till, and the areas represented primarily by soils formed in glaciofluvial and lacustrine deposits. The difficulty in determining this boundary was well documented by the former soil survey leader of the 1978 St. Clair County soil survey and his primary survey members. Historical correspondence between the soil survey party, the Illinois State Geological Survey, and the MLRA staff shows the difficulty and importance of making this determination. Unfortunately, the separations made by the soil survey party were dropped during correlation and final publication. This action was due to the emphasis on studying the soil to a depth of only 60 inches and to the emphasis on the taxonomic placement of pedons. The MLRA update surveys will include more detailed descriptions at greater depths in order to meet the demands of modern agriculture and urbanization.

Information Needed

A soil-geomorphic/soil-stratigraphy study would be appropriate to determine the characteristics and extent of the glacial lake and to examine the relationship of these deposits to the distribution of soils across the landscape. From this study we could expand our knowledge of geomorphology and pedogenesis and gain a greater understanding of the geologic history of the Kaskaskia River Basin.

Action and Assignments

(a) The MLRA update office requests the assistance of the staff at the National Soil Survey Center in Lincoln, NE. The Illinois Soil Survey Laboratory liaison is familiar with the area. He has expressed interest in working on this problem and would be of great assistance in determining the soil-geomorphic/soil-stratigraphy relationships.

(b) The coordinators for the study will be the MLRA project coordinator, the area soil scientist at Carbondale, IL, and the Illinois State Soil Scientist. I will be the contact person. Other participants will be personnel from the Illinois State University and soil scientists in MLRAs 113, 114, and 115.

(c) Deep cores taken with a hydraulic probe and pits will be used to describe soils and sediments and to collect samples for appropriate chemical, physical, and mineralogical analyses.

(d) The study will be carried out in stages. The first stage will begin in November in St. Clair County. Transects will be made across three major valleys in St. Clair County: the Kaskaskia, Silver Creek, and Richland Creek valleys. Deep cores (at depths > 20 feet) will be taken in transects perpendicular to each valley. A minimum of four cores will be taken in each transect; and each transect will begin in the upland and continue down an interfluve to the predicted terrace level, across the river channel to the terrace level on the other side, and again up an interfluve to the upland. Transect and core locations will be determined from topographic data and existing core data. We will determine the geomorphic and stratigraphic relationships with emphasis on identifying the presence or absence of the Sangamon Geosol. The Sangamon Geosol is a key marker in identifying upland positions.

(e) Tracing the Sangamon towards the streams will reveal where the Sangamon has been eroded out of the valley. At the erosional boundary we expect the surface to be covered by Wisconsinan deposits, and in places it may be lacustrine (slack water deposits). Therefore, we need to examine the water regime characteristics at this geologic boundary to determine its influence on the distribution of modern soils (especially "problem" soils, such as Natraqualfs).

(f) In places the development of the present soils in loess over the Pearl Formation with a Sangamon Geosol is different than that of the soils in loess over the Sangamon Geosol in till. The soils in the Pearl Formation are commonly developed to a greater depth and in places are better agronomic soils. This relationship may, in part, explain the higher yields of the Piasa mapped on the terrace as compared to the yields for the Piasa mapped on the upland.

(g) The results from the first stage of this study will be used to guide the investigations in other counties that contain Kaskaskia glaciofluvial and lacustrine sediments. After determining the soil geomorphic and soil stratigraphic relationships in St. Clair County, the next portion of the study will take place downstream in Monroe and Randolph Counties and upstream in Washington, Clinton, Fayette, Bond, and Marion Counties. We hope to begin this portion of the study in the spring of 1992. The goal is to map the areal distribution of glaciofluvial and lacustrine sediments in the eight-county study area and eventually throughout Southern Illinois and to determine the influence of these sediments on the genesis, morphology, classification, and management of the modern soils. The results of this study will be published and distributed to states that have extensive glaciofluvial and lacustrine sediments.

Summary of Plan of Action

(a) The MLRA project coordinator in conjunction with the Illinois State Geological Survey (ISGS) will perform a literature review. (Completed 11/91).

(b) The details of the experimental design and laboratory needs will be determined by the MLRA project coordinator, the area soil scientist, the liaison for the National Soil Survey Center, and the Illinois State Geological Survey. At this time we will determine what water table, hydraulic conductivity, and yield data are needed for the study. (Completed 11/91).

(c) The fieldwork for the study will begin with 1 or 2 weeks of fieldwork in 11/91 and with cooperation between the Illinois NRCS, ISGS, and the National Soil Survey Center.

(d) Information gathered from the first three steps will guide the direction of the next portion of the fieldwork that is to be carried out in 3/92.

(e) It is envisioned that the study will take 3 to 4 years to ensure sufficient collection of soils, yield, and water table data.

References

Fehrenbacher, J.B., R.A. Pope, I.J. Jansen, J.D. Alexander, and B.W. Ray. 1978. Soil productivity in Illinois. University of Illinois at Urbana-Champaign, College of Agriculture, Cooperative Extension Service, Circular 1156.

Wallace, D.L. 1978. Soil Survey of St. Clair County, Illinois. U.S. Government Printing Office, Washington, D.C.

Willmam, H.B., and J.C. Frye. 1970. Pleistocene stratigraphy of Illinois. Illinois State Geological Survey Bulletin, 94, 204 pp.

Example of a Soil Characterization Work Plan (Exhibit 631-5)

SOIL CHARACTERIZATION WORK PLAN

Identification:

Give the area or region of sampling, if appropriate, or the name(s) of soil survey area(s) if they are different from the county (counties) identified above.

Reason for Investigations Project:

Underscore the number for the primary reason(s) for the project.

1. Needs of current project soil survey
2. Survey update or modernization
3. Interpretations problem
4. Regional recorrelation or redefinition of series.
5. Study of genetic factors, processes, relationships
6. Support of other activity (such as an agronomic study)
7. Other (specify)

Intended Use of Project Information:

Underscore the number for the primary uses.

1. Characterize series or phase
2. Document experimental or study site(s)
3. Determine classification
4. Support correlation
5. Test Soil Taxonomy
6. Study soil relationships
7. Included in the published soil survey report
8. Other (specify)

For items 4, 5, 6, or 7, list questions to be answered.

Assistance Requested:

Status of Site Selection:

Persons or Agencies Responsible:

Other Pertinent Information:
(may be supplied by attachments, such as official series descriptions, if applicable)

Pedon 5:
Amego soil does not have free carbonates in the solum.
The soils mapped in Brown County do.

Complete Table 1 for all projects; list alternatives if purpose is to check classification. Complete other tables insofar as information is readily available.

Table 1 - Classification of Pedons to be Sampled

*Pedons to be sampled may not be representative of the named series but may become new series.

Table 2 - Extent of Series or Other Class Represented

Table 3 - Genetic Factors of Soil
(Attach block diagrams, geologic cross section, etc., if available)

Table 4 - Useful Data Available for These or Similar Soils
(Use lines as needed for each pedon to be sampled)