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NSSH Part 614

Applying Soil Taxonomy

Definition and Purpose (614.00)

The national system of soil classification identifies sets of soil properties and groups them in taxonomic classes. The system is dynamic and amended as needed. The purpose of soil classification is to order, name, organize, understand, remember, transfer, and use information about soils.

Policy and Responsibilities (614.01)

  1. The Natural Resources Conservation Service (NRCS) maintains and provides leadership for amending Soil Taxonomy and for maintaining the soil series classification files. All soil surveys within the National Cooperative Soil Survey must utilize Soil Taxonomy.
     
  2. The MLRA office is responsible for:
    • maintaining accurate and current descriptions of soil series,
    • approving changes to the type location of soil series,
    • soil series classification and the official soil series description files,
    • approving the names of soil series, and
    • approving all official series descriptions.
       
  3. All users are responsible for receiving, reviewing, and recommending the disposition of proposals to amend the soil classification system.
     
  4. The National Soil Survey Center is responsible for:
    • leadership for maintaining and amending Soil Taxonomy and for part 615 NSSH: Amendments to Soil Taxonomy,
    • maintaining the soil series classification and official soil series description file system, and
    • maintaining standards on the use of soil classification within the soil survey.

National Soil Classification System (614.02)

The national soil classification system has two parts:

  1. The first part is Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys, second edition, Agriculture Handbook No. 436, referred to as Soil Taxonomy, 2nd edition, latest revision. This part provides definitions and nomenclature for classifying soils. The National Cooperative Soil Survey (NCSS) adopted this system by in January 1965. The amendments to the system are in the NSSH part 615 until placed into the revised edition of Keys to Soil Taxonomy and the Web version of Soil Taxonomy.
     
  2. The second part consists of the official soil series descriptions. The Soil Survey Division maintains the official soil series description file and the soil series classification file. These files list the classification of established, tentative, and inactive soil series of the United States, Puerto Rico, the Pacific Basin, and the U.S. Virgin Islands. The official soil series description file is the official reference to soil series descriptions. The soil series classification file is the official source for the classification of the soil series. Both the official soil series description file and the soil series classification file are accessible by computer.

Use of the National Soil Classification System in Soil Surveys (614.03)

  1. Soil survey use Soil Taxonomy to provide:
    • a connotative naming system that enables those users familiar with the nomenclature to remember selected properties of soils,
    • a means for understanding the relationships among soils within a given area and in different areas,
    • a means of communicating concepts of soils and soil properties,
    • a means of projecting experience with soils from one area to another, and
    • names that can be used as reference terms to identify soil map unit components.

    Chapter 5, of Soil Taxonomy, 2nd edition, provides general information on the application of soil classification to soil maps of various scales.
     

  2. The names of soil taxa are reference terms for naming soil components of map units in most soil surveys. Soil taxa are classes at any categorical level in the multicategorical system of Soil Taxonomy. The name that is used is generally from a taxon of the lowest category that identifies the dominant kind or kinds of soil. Because soil taxa names can have several meanings, the names must be clearly understood. Page 124 of Soil Taxonomy provides more information. Even though names of one or more taxonomic classes identify map units, the map units are not the same as soil taxa. If the fixed limits of soil taxa are superimposed on the pattern of soils in nature, the limits of taxonomic classes rarely, if ever, coincide precisely with mappable areas. In addition to the named component or components, a map unit contains components of minor extent that are inclusions of other soils that may be similar or dissimilar to the named soil. Part 627 of this handbook discusses major and minor map unit components, inclusions, and dissimilar and similar soils.
     
  3. Distinguish a map unit name from a soil taxon name by adding one or more phase terms to the soil taxon reference name. For example, Gamma is a soil taxon; Gamma silt loam, saline, 0 to 2 percent slopes, is a map unit name. Part 627 of this handbook provides direction to naming map units. Chapter 20 of Soil Taxonomy and Chapter 5 of the Soil Survey Manual provide additional discussion of the relationship between soil taxa and map units and the naming of map units.

Soil Taxonomy Committees, Work Groups, and Referees (614.04)

  1. Regional Soil Taxonomy Committees. Each group of states within the experiment station region has a soil taxonomy committee (or other standards-related committee) as part of the Regional Cooperative Soil Survey Conference. The membership and operational procedures of the committee should be described in the regional conference by-laws. These committees work on standards-related issues that are identified as being important within the region, and also review proposed amendments that are referred to them from time to time by the National Leader for Soil Classification and Standards.
     
  2. National Soil Taxonomy Committee. The National NCSS Conference has a Standing Committee on Standards that includes some members from the regional committees as well as other members appointed by the Conference Steering Committee. The membership and operational procedures of the committee is described in the national NCSS conference by-laws. This committee works on standards-related issues that are identified by the Conference Steering Committee as being important, considers business items referred to it by the regional committees, and also reviews proposed amendments that are referred to them from time to time by the National Leader for Soil Classification and Standards.
     
  3. National ad hoc work groups. The Director, Soil Survey Division, appoints work groups, as needed. They review reports from regional soil taxonomy committees and recommend additional study or implementation of proposed amendments. Membership includes representatives of State and Federal agencies and may include international representatives. The groups have:
    • a chairperson, usually a member of the National Soil Survey Center staff, and
    • additional members, depending upon the nature of the recommended changes and the expertise needed.
       
  4. International committees. The Director, Soil Survey Division, establishes international committees if major national and international users of Soil Taxonomy identify a need for major additions or changes in the soil classification system. The Director appoints a chairperson. Membership is open to any user of Soil Taxonomy who chooses to participate and usually includes representatives of State and Federal agencies as well as international cooperators.
     
  5. Referees. The Director may request referees to prepare position papers on proposed amendments. The referee requests, as needed, a review by peers and assumes the responsibility for decisions regarding the proposal.

Procedures for Amending Soil Taxonomy (614.05)

  1. Submitting Proposed Amendments.
     
    1. Proposals may be made by anyone using Soil Taxonomy from within or outside the United States. Submit proposals that originate in the United States to the National Leader, Soil Classification & Standards or to the appropriate regional soil taxonomy committee chair.
       
    2. Submit proposals that originate outside the United States to the appropriate international committee or to the National Leader, Soil Classification & Standards, at the National Soil Survey Center, Federal Building, Room 152, 100 Centennial Mall North, Lincoln, Nebraska, 68508-3866.
       
  2. Documenting Proposed Amendments.
     
    1. Above the family level. The minimum supporting evidence for all proposed classes must include pedon descriptions, the impact on interpretations, an estimate of geographical extent, and certain laboratory data. The laboratory data must be on at least the critical parts of diagnostic horizons in the proposed new class if the limits between the proposed class and the other recognized classes cannot be adequately identified using field criteria alone.
       
    2. New family criteria. The minimum supporting evidence includes about 10 pedon descriptions or a description of a proposed soil series and the expected impact on interpretations for the intended use. Submit laboratory data on at least the critical parts of the proposed new class if the limits between the proposed class and the other recognized classes cannot be adequately identified using field criteria alone.
       
  3. Evaluating Proposed Amendments.
     
    1. The National Leader, Soil Classification & Standards, at the National Soil Survey Center circulates the proposed amendment to all cooperators for review. Review and comment is welcome from any interested cooperators. Those who are current members of the regional taxonomy committees have a special obligation to review and comment on proposals. Cooperators recommend (i) approval without change, (ii) approval with change, or (iii) rejection. Recommendations to change or reject the proposal are documented. The National Leader, Soil Classification & Standards, reviews the recommendations and either makes a decision to return the proposal to the originator with reasons for the rejection or includes the proposal in a part 615 NSSH issue. The Deputy Chief for Soil Survey and Resource Assessments signs the cover letter for the distribution of the issue and thus also gives final official approval for the changes.
       
    2. The National Leader, Soil Classification & Standards, evaluates all proposals from the international committees and other proposals that originate outside the United States, arranges for a review of these proposals by cooperators or work groups, and makes disposition of the proposals.
       
  4. Distributing Amendments.
     
    1. The publication of the amendments constitutes final approval. NRCS directives issue amendments that become additions to part 615 NSSH: Amendments to Soil Taxonomy. Updates of Keys to Soil Taxonomy include these amendments. All soil scientists of the NCSS and other soil scientists, both national and international, receive copies of amendments.
       
    2. The originator receives proposed amendments that are rejected along with recommendations for disposition.

The Soil Series (614.06)

The soil series is the lowest category of the national soil classification system. The name of a soil series or the phase of a soil series is the most common reference term used in soil map unit names. The name of a soil series is also the most common reference term used as a soil map unit component. The purpose of the soil series category is closely allied to the interpretive uses of the system, though map unit components provide the interpretive applications within soil survey for most detailed purposes. Soil series are the most homogeneous classes in the system of taxonomy.

Chapter 21, pages 832-836, of Soil Taxonomy provides guidance for series differentiae within a family.

  1. Establishing Norms and Class Limits for Soil Series.
     
    1. In developing or revising soil series concepts, systematic procedures are essential. They reduce the possibility of recognizing more soil series than are necessary to organize and present existing knowledge about soil behavior. The distinctions between one soil series and its competitors must be large enough to be consistently recognized and to be recorded clearly. Cleary differentiate each soil series from all other soil series. Simplify this differentiation by using the systematic procedure described in this section.
       
    2. Assemble and study all available information on morphology, composition, position on the landscape, and geographic distribution of the soils being considered. Compare the available information with the concepts of existing soil series, and evaluate possible concepts for new soil series. Refine soil characteristics that define higher categories of soil taxonomy to differentiate one soil series from another. These characteristics reflect the kind and sequence of horizons that can be observed, or they associate with characteristics that are observable and that can be consistently measured. Only use those characteristics that are observed or measured within the soil series control section to differentiate soil series. Chapter 21 of Soil Taxonomy provides more information on the series control section. A significant soil characteristic is one that has genetic implication, such as the nature or arrangement of horizons or the absence of horizons, or one that has an influence on use and management, such as percent of gravel or reaction. Exercise judgment in the selection and weighing of soil characteristics used to set apart soil series. Chapter 21 of Soil Taxonomy gives a further discussion of soil series and their differentiae.
       
    3. Competing soil series are those that are in the same family as the soil series under study. Changing the concept of one soil series likely stimulates modification to the concepts of other soil series in the family.
       
    4. When proposing a new series, conceptualize a model of it. Develop a model with a specific norm and range in characteristics for the proposed soil series description. Some of the characteristics of the new series will overlap the characteristics of an existing series; however, the range for differentiating characteristics cannot overlap with that of an existing soil series in the same family. Limits of the range in soil characteristics for the proposed soil series may be as wide as those permitted in the family to which it belongs. Generally keep the range in differentiating soil characteristics of the soil series narrower than that for the span of the family. Ranges cannot be too narrow for precise and consistent identification. They must be practical.
       
    5. Select a pedon that is typical for the soil series concept. The typical pedon is a reference specimen that illustrates the central concept for the soil series. This pedon, along with other very similar pedons, forms the model for the soil series class. Thus, the selection of a typical pedon is a very important process and is done with great care. Base it on the arrayed data on morphology, composition, and geographic distribution. No pedon is likely to be central for all ranges, but the representative pedon should lie reasonably near the center of the ranges for most physical and chemical properties and for the geographic distribution. If the pedon selected to typify a soil series has one or more properties unusual for the soil series class, record the the properties as part of the range of characteristics and note them in the “Remarks” section of the description.
       
    6. After selecting the typical pedon, define the permissible ranges in soil characteristics. Use the arrayed information on morphology and composition of the soils, especially the profile descriptions, field notes, and laboratory analyses.
       
    7. Only part of the set of observed properties define the classification of any soil, but consider all properties when defining the soil series. Not all observable soil properties are necessarily definitive for a soil series class. The definitive properties that set a soil series apart from similar competing soil series are essential. Emphasize these properties in the statement of the range of characteristics. Also describe the ranges in significant properties that do not differentiate between the soil series being described and its competing soil series.
       
    8. Next, test the soil series concept. Check the norm and ranges in characteristics against the class limits for the family to which the soil series belongs. Do not cross the limits of the family with the ranges specified for the soil series. The distinctions in definitive characteristics between the norms for the proposed soil series and the norms for competing soil series must be clearly greater than what may be normal errors of observation or be based on laboratory data and geomorphic or geographic information. Do not overlap ranges in differentiating characteristics.
       
    9. Differences in a single characteristic seldom set apart soil series. Use the distinctions in several characteristics to separate soil series. Some may have greater influence than others. Justify a new soil series if the differences in morphology and composition are clearly greater than what are normal errors of observation and affect use and management. It is hard to decide whether or not to propose a new soil series when two or more properties of the soils to be classified are outside but near the limits of an existing soil series. Propose new soil series if the soils differ in characteristics that have practical significance to use and management.
       
  2. Normal Errors of Observation. As a general guide, a new soil series differs appreciably in either morphology or composition, or both, from already defined soil series. Differences in relevant characteristics must be larger than what may be normal errors of observation or estimates. The following paragraphs give examples of allowed normal errors of observation and tolerance. Soils within these tolerances do not need a new series, nor do they need to be named as taxadjuncts.
     
    1. Identification of soil color in the field is subject to errors because of (i) changes in the quality of light and in soil moisture, (ii) differences in the visual acuity and skill of individuals, and (iii) limitations in the standards used to determine color. Chapter 3 of the Soil Survey Manual provides a discussion of soil color. Field observations of soil color are at different times of the day and have differing soil moisture contents. These variables could result in differences as large as a full interval between chips in the Munsell color system. The differences in identification of soil color resulting from one person looking at the same specimen at different times and under different conditions or from a group of individuals looking at the same specimen together are an example of normal errors of observation. Optimum field conditions allow soil color to be matched to within one-half interval between chips on the color chart. The normal range of difference between careful observations is plus or minus a half interval between chips of the same hue or between chips of the same value and chroma on adjacent hues. Color distinctions, if definitive, between the soils of two soil series must be greater than this normal range.
       
    2. Field estimates of textures are commonly within plus or minus one-half class of the actual texture, though errors by highly skilled individuals are smaller. To set apart soil series that are based in part on differences in texture, use distinctions that are greater than the probable error of field estimates or use laboratory data and geomorphic or geographic information. This rule applies to the entire soil series control section and any of its parts. Not all differences among soil series are obvious. The limit between fine-loamy and fine particle-size classes is a clay content of 35 percent. The experienced mapper has little difficulty in distinguishing between 30 percent and 40 percent clay. Only the laboratory can consistently distinguish between 34 percent and 36 percent. If this is the only difference, the distinction is not important for most uses of the soil map. Name the delineation for either of the two soil series that have a common conceptual boundary at 35 percent clay. Differences no greater than the normal errors of observation cause many needless decisions even for an experienced mapper. If the estimate of the properties varies by these normal errors, the similar inclusions that result do not seriously affect the use of the map if the map units are defined to allow for the variation.
       
  3. Proposing and Naming a Soil Series.
     
    1. Soil scientists in the National Cooperative Soil Survey write and complete descriptions of new soil series and their accompanying estimated properties. Part 627.08(e) contains documentation requirements.
       
    2. The soil series classification file contains a complete list of active and inactive soil series. The soil series classification file provides the official classification to the official soil series description file (OSD). Give preference to the names of geographic places as names for soil series. Avoid the following kinds of names:
      • names consisting of very long words or of two words;
      • bizarre, discriminatory, comical, and vulgar words;
      • geological terms, such as the names of rocks, minerals, landforms, and the formations of a locality;
      • names of animals and birds;
      • given names of persons, unless the name is a known geographic location;
      • copyrighted names and registered trademarks; and
      • names essentially identical in pronunciation or similar in spelling to a name already in use.

      Coin names if sufficient names of geographic places, which avoid all restrictions listed above, do not exist in a survey area or in the nearby area. Coined names must be consistent with American usage and free from the restrictions listed above.
       

    3. After review of the proposed soil series description within the MLRA office region, the MLRA office approves the name and reserves the name by entering the name and classification into the soil series classification file. The soil series description is identified as tentative. The MLRA office enters the soil series description into the official soil series description file, where it is available for adjoining MLRA offices and cooperators to review and comment.
       
    4. The MLRA office evaluates any comments and prepares a revision of the soil series description. The revised description is transmitted to the official soil series description file. If the decision is made not to use the series, remove the tentative soil series from the soil series classification file. This will cause the tentative soil series description to move to an inaccessible file.
       
    5. The MLRA office resolves disagreements on concepts of soil series. They assemble and evaluate available evidence on the points in question, and, if necessary, request additional information about the soils under consideration from one or more MLRA regions. If the soil series is in dispute or if the questions about the soil series concept are of considerable importance, a joint field study may be necessary. After the differences have been resolved, the MLRA office updates the soil series description in the official soil series description file.
       
  4. Revising Official Soil Series Descriptions.
     
    1. Soil scientists must revise soil series descriptions if one or more of the following conditions exists:
      • change in the concept of the soil series, including the range in characteristics;
      • change in the classification of the soil series; and
      • change in the type location of the soil series.
         
    2. Any soil scientist in the NCSS can write revisions of soil series descriptions. Submit these descriptions to the MLRA office assigned to the type location for the series. Base the revision on pedon descriptions, laboratory data, and other available sources of information about the soils that represent the series.
       
    3. If the soil series classification or type location is changed, the MLRA office reviews these changes within MLRA office region and with other MLRA office regions in which the soil series or competing series are known or expected to occur. After critical review, reviewing scientists return comments to the originating MLRA office. The MLRA office soil scientist evaluates the comments and makes the necessary changes in the revised description of the soil series. The MLRA office updates the classification of the soil series in the soil series classification file, if necessary, and then transmits the revised description to the official soil series description file.
       
  5. Inactivating an Established Soil Series. The MLRA office places established soil series on the inactive list when appropriate. Support the decision to inactivate a soil series with documentation as to why the soil series should be made inactive and include a recommendation for the disposition of the soils that have been classified as the inactive series. Before placing a soil series on the inactive list, the MLRA office sends a memorandum of intentions and supporting reasons to affected MLRA offices. The MLRA office notifies other disciplines and cooperators who may use the series name in databases and publications. Allow forty-five days for filing objections to the recommendation. If the MLRA office determines that the soil series should be made inactive, they notify the affected regions. The memorandum includes the reclassification to the appropriate soil series or to a taxon of a higher category of all pedons in the inactive series that have been sampled and analyzed by the NRCS, cooperating universities, highway departments, or other laboratories. List inactive soil series in the soil series classification file.
     
  6. Reactivating an Inactive Soil Series Name. Do not reuse the name of a soil series that is placed on the inactive list unless the series concept is the same as in the previous description. If an MLRA office wants to reactivate a soil series name, they follow the procedure that is used to propose a soil. Make a notation under "Remarks" that the soil series name is being reactivated.
     
  7. Dropping a Tentative Soil Series. Drop a tentative soil series from the soil series classification list if it duplicates an already recognized series.
     
    1. If multiple MLRA offices use the soil series, the MLRA office with the series type location requests concurrence from user MLRA offices to drop the series. Upon concurrence, the MLRA office notifies the users that the series is dropped. The notification includes a statement of reasons for dropping the series. Note the name of the dropped series in the correlation document of the soil survey area that has the type location.
       
    2. If only the originating MLRA office is using a soil series listed as tentative, drop the series by listing it as dropped in the correlation document of the survey area that has the type location.
       
    3. Remove the name and record from the soil series classification file, this causes the the description in the official soil series description file to move to an inaccessible file. Do not list a tentative soil series as inactive.
       
  8. Transferring Responsibility for a Soil Series and Changing the Type Location. Approval for transfer of the responsibility for a soil series and change of type location is as follows:
     
    1. The MLRA office approves changes within the MLRA office region.
       
    2. Mutual consent of the MLRA offices allows transfers between MLRA office regions.

    All transfers of a soil series responsibility and change of type location require a series description using the new type location. The MLRA office enters the new description into the database.
     

  9. Establishing a Soil Series. A soil series is established when it is used in the correlation of a survey area and the correlation document is approved and signed by the MLRA office. The correlation document contains a list of the soil series that are established by that correlation. If a soil series is established by a correlation, the responsible MLRA office changes the status of the series in the official soil series description file and soil series classification file from “tentative” to “established” and also changes the heading “series proposed” to “series established.” The MLRA office also enters in the official soil series file the year that the soil series is established and the name of the survey area in which it is established. The MLRA office transmits the updated description to the official soil series description file and the soil series classification file. If the tentative soil series is not established and no other potential use is pending, remove the soil series from the soil series classification file.
     
  10. Official Soil Series Descriptions.
     
    1. “Official soil series description” is a term applied to the description approved by the MLRA offices, which defines a specific series in the United States. The description follows a prescribed format. Revise an official soil series description if more information about the soils in the series is available. All soil scientists working in the NCSS must be familiar with the requirements for adequate soil series descriptions. The Soil Survey Manual and Chapter 21 of Soil Taxonomy discuss the concept of the soil series and requirements for descriptions.
       
    2. The official soil series descriptions are descriptions of the taxa in the series category of the national system of soil classification. They mainly serve as specifications for identifying and classifying soils. Field soil scientists must have access to all the existing official soil series descriptions that are applicable to their soil survey areas and other official soil series descriptions that include soils in adjacent or similar survey areas. Scientists in other disciplines, such as agronomists, horticulturists, engineers, planners, and extension specialists, also use the descriptions to learn about the properties of soils in a particular area.
       
    3. The format for descriptions and the order in which the major items appear are as follows:
      • location line,
      • status of soil series (tentative or established),
      • initials of authors,
      • name of soil series,
      • introductory paragraph,
      • taxonomic class,
      • typical pedon,
      • type location,
      • range in characteristics,
      • competing series,
      • geographic setting,
      • geographically associated soils,
      • drainage and saturated hydraulic conductivity,
      • use and vegetation,
      • distribution and extent,
      • MLRA office responsible,
      • series proposed or series established,
      • remarks on diagnostic horizons and features recognized in the pedon, and
      • additional data.

      Every official soil series description includes all but the “additional data” item, which is used only as needed. Exhibit 614-1 is an example of an official soil series description. Exhibit 614-2 explains the content of a soil series description.
       

    4. Each description must be complete and as brief as possible without omitting any essential information. It must clearly differentiate between the series being described and all other series. It states the present concept of a soil series rather than past concepts or its evolution. The description must record the soil properties that:
      • define the soil series,
      • distinguish it from other soil series,
      • serve as the basis for the placement of that soil series in the soil family, and
      • provide a record of the soil properties needed to prepare soil interpretations.
         
    5. In the competing series paragraph, give differentiae in terms of soil properties, diagnostic horizons, or features. A simple statement that gives the classification of a series in categories of the system is inadequate.
       
    6. Use the standard terminology that is defined in the Soil Survey Manual as appropriate. If applicable, use terms defined in Soil Taxonomy. The rule for the use of standard terms applies to all parts of soil series descriptions but is especially important for descriptions of individual horizons. Some soil descriptions need to use some terms that are not defined in the Soil Survey Manual or Soil Taxonomy. Use such terms in their ordinary, standard dictionary sense.

Example of an Official Soil Series Description (Exhibit 614-1)

LOCATION GAMMA AA
Established series
Rev. AAA-BBB-CCC
5/91

GAMMA SERIES
The Gamma series consists of very deep, well drained soils that formed in marine sediments. The Gamma soils are on broad tops and side slopes of deeply dissected high marine terraces. Slope ranges from 0 to 30 percent. The mean annual temperature is 11 degrees C, and the mean annual precipitation is about 2030 mm.

TAXONOMIC CLASS: Fine-loamy, siliceous, semiactive, isomesic Typic Palehumults.

TYPICAL PEDON: Gamma loam, on a north-facing, convex, 4 percent slope under conifers at an elevation of 200 meters. (Colors are for moist soil unless otherwise noted. When described on March 13, 1991, the soil was moist throughout.)

Oi--0 to 5 cm; fibric material; slightly decomposed needles, leaves, twigs, and other woody materials. (2 to 8 cm thick)

A1--5 to 13 cm; very dark grayish brown (10YR 3/2) loam, dark grayish brown (10YR 4/2) dry; weak very fine subangular blocky structure parting to weak fine granular; slightly hard, friable, nonsticky and nonplastic; weakly smeary; many fine and very fine and few medium and coarse roots; many fine and very fine pores; very strongly acid (pH 4.9); clear smooth boundary.

A2--13 to 43 cm; very dark grayish brown (10YR 3/2) loam, dark brown (10YR 4/3) dry; weak very fine subangular blocky structure parting to weak fine granular; slightly hard, friable, nonsticky and nonplastic; weakly smeary; many very fine and fine and few medium and coarse roots; many very fine and fine irregular pores; very strongly acid (pH 4.5); abrupt smooth boundary. (Combined thickness of the A horizon ranges from 25 to 50 cm.)

2Bt1--43 to 80 cm; dark brown (7.5YR ¾) loam, strong brown (7.5YR 5/6) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine and few medium and coarse roots; many very fine continuous tubular pores; few faint clay films on faces of peds; common faint clay films in pores; 10 percent gravel; very strongly acid (pH 4.9); gradual smooth boundary.

2Bt2--80 to 100 cm; reddish brown (5YR 4/4) loam, yellowish red (5YR 5/8) dry; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common fine and few medium and coarse roots; common very fine continuous tubular pores; common distinct clay films on faces of peds and in pores; 10 percent gravel; very strongly acid (pH 5.0); clear smooth boundary.

2Bt3--100 to 135 cm; brown (7.5YR 4/4) clay loam, strong brown (7.5YR 5/6) dry; moderate medium and coarse subangular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; common fine and few medium and coarse roots; many very fine continuous tubular pores; common distinct clay films on faces of peds and in pores; 10 percent gravel; very strongly acid (pH 5.0); gradual smooth boundary. (Combined thickness of the 2Bt horizon is 75 to 120 cm.)

2BC--135 to 160 cm; yellowish red (5YR 4/6) gravelly clay loam, strong brown (7.5YR 5/8) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; common fine continuous tubular pores; 20 percent gravel; very strongly acid (pH 5.0); gradual smooth boundary. (15 to 40 cm thick)

2C--160 to 200 cm; yellowish red (5YR 4/6) gravelly clay loam, reddish yellow (5YR 6/6) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; common fine continuous tubular pores; 20 percent gravel; very strongly acid (pH 5.0).

TYPE LOCATION: Any County, Anystate; located about 750 feet south and 2,220 feet east of the northwest corner of sec. 31, T. 40 S., R. 13 W; USGS named topographic quadrangle; lat. 42 degrees 4 minutes 31 seconds N. and long. 95 degrees 17 minutes 30 seconds W., NAD 83.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is 10 to 12 degrees C, the mean summer soil temperature is 12 to 14 degrees C, and the mean winter soil temperature is about 8 to 10 degrees C. The difference between the mean summer and winter temperatures ranges from 3 to 4 degrees C. The soils are usually moist, and they are dry for less than 45 consecutive days in all parts between depths of 10 and 30 cm in the four months following the summer solstice. The particle-size control section averages 25 to 35 percent clay. All horizons are very strongly acid or extremely acid. The umbric epipedon is 25 to 50 cm thick.

The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist or 3 or 4 dry, and chroma of 2 or 3 moist or dry. It is 10 to 20 percent clay, 30 percent sand, and has 0 to 10 percent gravel.

The 2Bt horizon has hue of 7.5YR or 5YR, value of 3 or 4 moist or 4 or 5 dry, and chroma of 4 to 6 moist or 6 to 8 dry. It is gravelly loam, gravelly clay loam, loam, or clay loam. It averages 25 to 35 percent clay, 30 to 45 percent sand, and 5 to 20 percent gravel.

The 2BC horizon has hue of 7.5YR or 5YR, value of 4 to 6 moist or 5 to 8 dry, and chroma of 6 to 8 moist or dry. It is gravelly loam, gravely clay loam, loam, or clay loam. It averages 25 to 35 percent clay, 30 to 45 percent sand, and 10 to 30 percent gravel.

The 2C horizon has hue of 7.5YR or 5YR, value of 4 to 6 moist or 6 to 8 dry, and chroma of 6 to 8 moist or dry. It is gravelly loam, gravelly clay loam, loam, or clay loam. It averages 25 to 35 percent clay, 25 to 45 percent sand, and 10 to 30 percent gravel.

COMPETING SERIES: This is the Beta series. Beta soils have less than 30 percent sand in the argillic horizon and hue of 10YR or yellower throughout the argillic horizon.

GEOGRAPHIC SETTING: The Gamma soils are on broad summits and side slopes of deeply dissected high marine terraces. Slope ranges from 0 to 30 percent. The soils formed in marine sediments. Elevations are 180 to 250 meters. The climate is humid and characterized by cool wet winters and cool moist summers with fog. Because of a strong marine influence, the diurnal and annual ranges of temperature are limited. The mean annual precipitation is 1800 to 2300 mm. The mean annual temperature is 10 to 12 degrees C. The frost-free period is 210 to 300 days. The Gamma soils are on the Griggs geomorphic surface.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Delta and Gamma soils. Delta soils have 35 to 45 percent clay in the argillic horizon and are on an adjacent higher marine terrace. Gamma soils have a cambic horizon, have an umbric epipedon that is 50 to 75 cm thick, and are on an adjacent lower marine terrace.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, low to high runoff, moderately high saturated hydraulic conductivity.

USE AND VEGETATION: These soils are used for homesites, timber production, recreation, water supply, pasture, and wildlife habitat. Native vegetation is Sitka spruce, Douglas-fir, red alder, red elderberry, salmonberry, evergreen huckleberry, sala, western swordfern, evergreen violet, and sweetscented bedstraw.

DISTRIBUTION AND EXTENT: Pleistocene marine terraces in northwestern U.S.A.; MLRA 1. The series is of moderate extent.

MLRA OFFICE RESPONSIBLE: City, State.

SERIES ESTABLISHED: Any County, Anystate, 1991.

REMARKS: Diagnostic horizons and features in this pedon include:
Umbric epipedon - from a depth of 0 to 43 cm (A1 and A2 horizons).
Argillic horizon - from a depth of 43 to 135 cm (2Bt1, 2Bt2, and 2Bt3 horizons).

ADDITIONAL DATA: Partial reference samples from pedon 89P197, samples 89P1199-1202 from Any County, Anystate, samples by SSL, Lincoln, NE, 12/89. Soil Interpretation Record: AA0023.

National Cooperative Soil Survey
U.S.A.

Explanation and Content of a Soil Series Description (Exhibit 614-2)

After the introductory paragraph, the format for soil series descriptions arranges the subject matter in two main parts. The first part includes the taxonomic classification, the description of the typical pedon, the type location, the section on range in characteristics, and the section on competing series. This part and the description of the diagnostic horizons and features in the “Remarks” section defines the soil series as a class in the soil classification system insofar as the available information permits. The second part includes all the remaining sections of the soil series description. It provides additional descriptive information.

The guidelines for keying soil series descriptions are as follows:

  • Left margin is in column 1. Right margin is in column 66.
  • Tabs, stop codes, required hyphen codes, required backspace codes, automatic centering, and underlines are not used. The spacebar is used instead of tabs.
  • Everything is left justified except the horizon designations, which are indented 4 spaces (to column 5), using the spacebar.
  • Section headings are in capital letters, for example, TAXONOMIC CLASS, and TYPICAL PEDON.
  • Depths and thickness (cm), temperature (degrees C), precipitation (mm), and elevation (m) are in metric units of measure; acreage and legal descriptions (long, lat, minutes, seconds, and NAD are preferred) are in English units. General locations can be given in feet and miles.
  • Special symbols, subscripts, and superscripts must be expressed as words.

For example: 10° is changed to 10 degrees, CaC03 is changed to calcium carbonate, and 10% is changed to 10 percent.

  • The first 8 lines and the last line of the soil series description must be standardized in order for the OSED computer program to work. All entries are left justified and start in column 1.

Line-By-Line Instructions

Line 1--LOCATION GAMMA NE (This line is entered in capital letters. The first letter of the state where the soil series is located must be in column 33.)

Line 2--Blank line

Line 3--Tentative Series or Established Series

Line 4--Rev. MLD-JRC (These are the initials of the individuals who last revised the soil series.)

Line 5--7/87 (This is the month and year that the soil series draft was sent to the official series description file. The system enters this date automatically.)

Line 6--Blank line

Line 7--GAMMA SERIES (All letters are capped.)

Line 8--Blank line

Line 8 is followed by the introductory paragraph and the rest of the soil series description.

Next to last line--National Cooperative Soil Survey

Last line--U.S.A. (All letters are capped and do not have spaces in between.)

The completed description must be run through spell check.

Content of Soil Series Description

(a) Introductory paragraph

Introductory paragraph. This paragraph carries no side heading. It briefly describes the depth, drainage, soil-forming materials, and any other significant soil features that characterize the soil series and the geographic setting. This information benefits people who refer to the official soil series descriptions but are not well acquainted with the classification system. If used in the introductory paragraph, depth refers to depth to bedrock unless some other feature that is important to plants or engineering interpretations is specified. If a restrictive feature is at some depth within the soil profile, describe it by stating "very shallow to sandstone or shale," "very deep soils that are moderately deep to gravel," or "moderately deep to rhyolite and shallow to a duripan." The temperature and precipitation are mean annual values for the soil series. Do not use the terminology in Soil Taxonomy in the introductory paragraph. Examples of this paragraph are:

  • The Gamma series consists of deep, well drained soils on moraines, drumlins, and till plains. These soils formed in a thin layer of loess and the underlying loamy glacial till. Saturated hydraulic conductivity is moderately high in the subsoil and moderately high or moderately low in the underlying material. Slope ranges from 0 to 25 percent. The mean annual precipitation is about 600 mm, and the mean annual temperature is about 8 degrees C.
  • The Beta series consists of very poorly drained, organic soils in drainageways and depressions on moraines, lake plains, and outwash plains. These soils formed in highly decomposed organic material over loamy glacial and lacustrine sediments. The organic material was derived from herbaceous plants. Saturated hydraulic conductivity is moderately low in the organic material and moderately high in the underlying material. Slope ranges from 0 to 2 percent. The mean annual precipitation is 800 mm, and the mean annual temperature is 2 degrees C.

(b) Taxonomic class

This statement gives the family classification. If the classification is questionable, explain it in the “Remarks” section.

(c) Typical pedon

Use the side heading in the description, as indicated. The soil series name and texture phase term or the word “series” follow the side heading. Next is the aspect, shape, and percent of slope and a word or phrase, such as “forested,” “pasture,” “cultivated field,” or other term for use or cover, that shows whether or not the soil at the site has been disturbed. Place a parenthetical statement immediately below the heading and soil name to specify the moisture state of the soil when it was described. If the soil was nearly dry in the upper 60 cm and moist below, the statement, “When described, the soil was slightly moist above a depth of 60 cm and moderately moist below is used.” An example of this paragraph is:

  • Gamma silt loam on a southeast-facing, concave, 3 percent slope under mixed hardwoods at an elevation of 500 meters. (Colors are for moist soil unless otherwise stated. When described on July 1, 1985, the soil was slightly moist to a depth of 60 cm and moderately moist below that depth.)

(1) Descriptions of horizons. These descriptions are in paragraph form. They ordinarily consist of three parts: the horizon designation, the horizon depths, and the description of the horizon.

(2) Pedon described. Describe an actual pedon. The pedon chosen as the typical pedon must reflect the norm for the soil series as closely as possible. The norm is the concept or mental image of the central nucleus of pedons for the soil series. The pedon may depart in minor ways from the norm without a need for explanation. If it departs from the norm in some obvious feature, however, indicate the departure in the range of characteristics and in the “Remarks” section of the description. Describe the typical pedon in its dominant land use. Describe the pedon to a depth that is at least equal to that for the series control section. Describe the relevant characteristics of R and Cr layers.

(3) Identification of horizons. Identify horizons using the horizon designations defined in Chapter 3 of the Soil Survey Manual and the 9th edition of the Keys to Soil Taxonomy. Terms that are used for diagnostic horizons of the soil classification system do not define horizons.

(4) Depth of horizons. Give the depths to the upper and lower boundaries of horizons in centimeters and follow the corresponding horizon designations. Insert a semicolon after “cm.” Use the soil surface, excluding live and fresh leaves and twigs, as a reference plane for depth and thickness measurements for all mineral and organic soil horizons.

(5) Features described for horizons. These features are as follows:

  • color (dry or moist, the most common condition),
  • texture,
  • color (dry or moist, opposite of the condition initially given),
  • mottles (dry or moist, non-wetness related),
  • structure (Do not use commas to separate terms in the phrase that describes structure. Use the word “structure” only once in describing compound structure. For example, “weak coarse prismatic structure parting to moderate medium subangular blocky.”),
  • consistence (dry, moist, stickiness, plasticity),
  • roots,
  • pores,
  • additional features (as in item 8 that follows),
  • reaction,
  • lower boundary, and
  • range in thickness.

(6) Sequence for describing features. Describe the features of each horizon in the order listed to make comparisons easier among horizons and among soil series. All features may not occur in every horizon. As previously specified, describe features in standard terminology as much as possible.

(7) Color. Give descriptions of colors, including Munsell notations, for individual horizons. Describe color by using Munsell notations to the nearest color chip. All surface horizons require both moist and dry colors. Other horizons require colors for both moist and dry conditions if the information is necessary for the classification of the soil series. Record colors for both dry and moist conditions even if the information is not required for classification, if known. Give moisture conditions for individual color identifications or for the whole pedon, as previously specified. Most horizons have a dominant color that changes in value and, less commonly, in hue and chroma as the moisture content changes. The color listed first represents the moisture content that is most often observed. In arid regions this is the color of dry soil, and in humid regions it is the color of moist soil. In the description of the horizon, first record the color of the matrix or interiors of the peds; then list the color of films or coating on peds if they are different from the interiors. Identify the positions of individual colors unless they are obvious from the context. Do not use hyphens in soil color names.

(8) Additional features. List these features separately because they do not occur in all soils or horizons. They include without implying order:

  • slickensides,
  • durinodes,
  • plinthite,
  • clay films,
  • concretions,
  • carbonates,
  • salts,
  • sodium,
  • smeariness,
  • redoximorphic features
  • pebbles, stones, and other fragments, and
  • brittleness.
  • .

If such features are not mentioned in the description of a horizon, assume them to be absent. If these features are described, give the size, the color (if appropriate), the kinds, and numbers of concretions, stones, and pebbles; the distinctness, extent, color, and position of clay films; and the amounts and distribution pattern of carbonates, and salts. Use the nomenclature for diagnostic features, such as slickensides, durinodes, and plinthite, in the horizon description.

(9) Reaction. Record reaction using the descriptive terms listed in Chapter 3 of the Soil Survey Manual. Give the pH value in parentheses following the descriptive terms.

(10) Range in thickness of individual horizons. Although this range is part of the range in characteristics for the soil series, include it in parentheses with each horizon description in the typical pedon for convenience. However, the combined thickness of subhorizons may be given.

(11) Examples of descriptions of individual horizons.

(i) A sequence of two horizons:

Oe1--0 to 20 cm; dark reddish brown (5YR 3/2) mucky peat, broken face hemic material, very dark brown (10YR 2/2) rubbed; about 60 percent fiber, 25 percent rubbed; massive; herbaceous fiber; about 15 percent mineral material; slightly acid (pH 6.5 in 1:2 0.01 M calcium chloride); abrupt smooth boundary.

Oe2--20 to 45 cm; very dark grayish brown (10YR 3/2) mucky peat, broken face and rubbed hemic material; about 40 percent fiber, 20 percent rubbed; massive; herbaceous fiber; about 35 percent mineral material; few small snail shells; strongly effervescent; slightly alkaline (pH 7.6 in 1:2 0.01 M calcium chloride); abrupt smooth boundary. (Combined thickness of Oe horizons is 15 to 50 cm.)

(ii) A sequence of three horizons:

E--2 to 25 cm; light yellowish brown (2.5Y 6/4) loam, very pale brown (10YR 7/3) dry; weak thin platy structure; soft, very friable, slightly sticky, non-plastic; few fine roots; few very fine pores; few fine black and dark brown concretions; 2 percent cobbles; strongly acid; clear smooth boundary. (15 to 30 cm thick)

Bt1--25 to 50 cm; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong coarse columnar structure; clean silt caps about 1 inch thick on tops of columns and clean sand grains on sides of columns; extremely hard, firm, moderately sticky and moderately plastic; common fine roots; many very fine vesicular pores in caps, many very fine tubular pores immediately below caps; few medium pores in lower part of columns; many distinct very dark brown (10YR 2/2) clay films on faces of columns; common dark stains on sides of columns; moderately alkaline; clear wavy boundary. (18 to 56 cm thick)

2Bt2--50 to 75 cm; olive (5Y 5/3) silty clay loam; moderate fine subangular blocky structure; hard, firm, moderately sticky and slightly plastic; few fine tubular pores; common fine prominent brown (10YR 5/3), many fine prominent yellowish brown (10YR 5/8) masses of iron accumulation; common fine prominent gray (10YR 5/1) iron depletions; common distinct very dark grayish brown (2.5Y 3/2) clay films in pores and on faces of peds; thin black (5Y 2/1) flecks inside peds; slightly acid; gradual wavy boundary. (15 to 35 cm thick)

(iii) A single horizon:

Cg3--125 to 150 cm; gray (10YR 5/1) silty clay loam; massive; firm, friable, moderately sticky and slightly plastic; few fine roots; few fine tubular pores; few medium distinct pale brown (10YR 6/3) masses of iron accumulation; common black (10YR 2/1) medium concretions and masses of oxide accumulation; common reddish brown (5YR 4/4) pore linings around former root channels; moderately acid; gradual smooth boundary.

(12) General guidance for preparing pedon descriptions.

(i) Use “few”, “common”, or “many” for classes of numbers of redoximorphic features, roots, pores, and concentrations. Refer to Chapter 3 of the Soil Survey Manual for a definition of the terms that apply to each of the features. Express rock fragments as a percentage of the volume.

(ii) Use “uncoated” or “clean silt and sand grains” rather than “bleached silt and sand” or “grainy coats.”

(iii) “Ped” is the preferred terminology for a natural structural unit. Clods and fragments result from tillage or cultural practices. The term “aggregate” is confusing because it has many different meanings. Use the expression “faces of peds” and not “ped faces.”

(iv) Avoid expressions such as “weak to moderate” for grade of structure (or other property). Use “weak and moderate” if two grades of structure are present. If peds separate to form smaller peds, use the verbs “part” or “separate” to describe the formation of secondary peds. In contrast to a complete ped, a fragment of a ped has fracture surfaces rather than natural faces. The zero grade of structure (structurelessness) is single grain or massive. Do not use the term “structureless” because it is redundant if used with “massive” or “single grain.” Do not use secondary structure with massive or single grain.

(v) By definition concretions are cemented and hard. Thus, the phrase “soft lime concretions” is not correct. Use “soft calcium carbonate accumulations” or some other appropriate description. Preferred expressions are:

  • common fine dark concretions (Fe & Mn oxides) or
  • common fine dark concretions (oxides).

(vi) Carbonates commonly are criteria to set apart soil series. Carbonates may be present in segregated forms or disseminated in parts of the mass or throughout the mass. Soil series descriptions must specify the kind and the distribution of carbonates within horizons.

The degree of effervescence after the soil is treated with 1N hydrochloric acid is described as very slightly, slightly, strongly, and violently effervescent. The degree of effervescence is related to the surface area of the carbonate minerals and to the kinds of minerals rather than to the total lime content.

Thus, effervescence is not a reliable basis for estimating the amount of carbonates. A small amount of finely divided carbonates can produce a violent effervescence for a short time. Field tests for estimating the amount of carbonates in a soil are available. Record the content in parentheses after the degree of effervescence, such as “strongly effervescent (8 percent calcium carbonate).”  Estimate carbonates to the nearest 1 percent if less than 20 percent; and to the nearest 5 percent if it is more than 20 percent. An example is “slightly effervescent (2 percent calcium carbonate); slightly alkaline.”

(vii) If E and Bt horizons are described, parts that refer to each horizon are indicated as follows:

E and Bt--95 to 145 cm; yellowish brown (10YR 5/4) fine sand (E); single grain; loose; lamellae and bands of dark brown (7.5YR 4/4) fine sandy loam (Bt); coarse subangular blocky structure in thicker bands; friable; wavy and discontinuous 2 to 4 cm thick lamellae in upper part and bands 5 cm thick in lower part; moderately acid; gradual wavy boundary. (40 to 75 cm thick)

(viii) Neutral colors are written such as N 5/. The hue is neutral if the chroma is 0.

(ix) Do not place a plus sign after the last stated depth in the profile description. The last stated depth is the depth to which the profile was examined.

(x) Chapter 3 of the Soil Survey Manual and the 9th edition of the Keys to Soil Taxonomy give the designations used for horizons and layers.

(xi) Indicate the range in thickness of horizons as follows:

  • The thickness of horizons that have two or more subhorizons can be combined. Note the range in thickness after the last subhorizon. For example, “The combined thickness of the Bw horizon is 50 to 75 cm.”

     
  • The thickness of horizons that are not essential to the classification and are not in all profiles is expressed as zero to an appropriate number of inches. For example, “0 to 60 cm thick.”

(d) Type location

The location is a specific site, which gives the county and state names first. It is described accurately enough in relationship to map coordinates or other geographic reference points that it could be located by a person unfamiliar with the area. For example:

  • Lucky County, Nebraska; about 10 miles north and 7 miles east of Eden; 100 feet west and 30 feet south of the northeast corner of sec. 7, T. 12 N., R. 26 W.; USGS named topographic quadrangle; lat. 40 degrees 40 minutes 20 seconds N. and long. 40 degrees 30 minutes 20 seconds W., NAD 83.

Give the latitude, longitude, and NAD in both sectionized and non-sectionized areas. In sectionized areas, the four section corners and the center of a section may also reference points. Do not use the term “1/4 corners” in giving the location. In nonsectionized areas, give locations using available permanent landmarks.

(e) Range in characteristics

This section spells out observed ranges in soil properties for the soil series class as it is currently conceived. Give emphasis to properties that are definitive for the soil series or that affect use and management whether or not these properties are known to differentiate locally. As much as practical, give quantitative limits for the ranges in properties. The ranges specified must fall within the ranges of the family in which the soil series is classified. If the allowable range in a given property coincides with the range of the family or a higher category, the range does not have to be repeated in the description because it is implied by the classification given. A range in a soil series property commonly is narrower than the range for the family class. If it is, give the narrower range. If class limits in the classification system are soil series limits, observe these limits before recording their values. The ranges given are those that are considered to be limiting for the soil series and do not extend to taxadjuncts. The inclusion of unusual ranges in properties magnifies problems of identifying soil series apart from one another. Limit the recorded ranges to those that have been observed in the field or determined in the laboratory. Record assumed properties in the “Remarks” paragraph. This section of the soil series description, like others, is not meant to cover the inclusions of soils of other series within map units. Record such inclusions in the map unit descriptions in soil survey area handbooks, descriptive legends, and soil survey manuscripts rather than in the official soil series descriptions. A standard arrangement of information in this section makes comparisons among soil series easier. Both tabular or text formats are acceptable. The arrangement first presents information on the soil as a whole, and then presents in subsequent paragraphs information on the major individual horizons.

A standard arrangement of information in this section makes comparisons among soil series easier. Both tabular or text formats are acceptable. The arrangement first presents information on the soil as a whole, and then presents in subsequent paragraphs information on the major individual horizons.

(1) First paragraph. Include general pedon features that apply to the soil as a whole rather than to individual horizons in this paragraph. Present such features as the thickness of the subsoil, depth to bedrock, depth to a fragipan, stoniness, mineralogy, range in soil temperature, and frequency and duration of periods when soil moisture is at or below the wilting point. Information that has been obtained through direct observations or that can be reliably inferred is recorded.

An example of a tabular format is : 

              Soil moisture:   Moist in some part of the soil moisture control
                               section December to March; intermittently moist
                               July to September; driest in May and June; ustic
                               moisture regime that borders on aridic.
           Soil temperature:   9 to 13 degrees C.
             Rock fragments:   15 to 50 percent gravel and 10 to 25 percent
                               cobbles; average of more than 35 percent in the
                               particle-size control section.
Calcium carbonate equivalent:  15 to 40 percent.
            Depth to bedrock:  7 to 20 inches.
                    Reaction:  Slightly alkaline or moderately alkaline.
              Organic matter:  Average of 1 to 5 percent in the surface layer.
                Clay content:  18 to 25 percent; textures of loam or silt loam
                               with less than 40 percent sand.

(2) Subsequent paragraphs. Describe each major horizon of mineral soils in a separate paragraph. Separate each paragraph with a double space. Use tiers or combinations of similar layers for organic soils.

(i) The horizons covered in the subsequent paragraphs are the major ones described and are of consequence to the definition of the soil series. Discuss the ranges in soil properties in the same order as they are listed in the typical pedon description. An example of text format is:

“The Bt horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist or 3 or 4 dry, and chroma of 1 or 2 moist or dry. It is loam or clay loam. It averages 18 to 28 percent clay and 40 to 60 percent fine sand or coarser material. It has weak or moderate medium subangular blocky structure and is friable or very friable. It ranges from slightly acid to slightly alkaline.”

An example of tabular format is: 

Bt horizon
Hue:  10YR, 7.5YR.
Value:  2 or 3 moist, 3 or 4 dry.
Chroma:  1 or 2 moist or dry.
Texture:  Loam, clay loam.
Clay:  18 to 28 percent.
Fine sand or coarser material:  40 to 60 percent.
Structure:  Weak or moderate medium subangular blocky.
Moist consistence:  Friable or very friable.
Soil reaction:  Slightly acid to slightly alkaline.

(ii) Subdivisions of major horizons may be helpful for some soil series. The sequence begins with the uppermost horizon in the pedon and continues downward. Make subdivisions of major horizons only if necessary because the resulting long and detailed section may obscure important information.

(iii) List the most common range of a soil characteristic before giving the complete range. For example, “The A horizon commonly is loamy sand and less commonly is loamy fine sand, fine sand, or fine sandy loam” or “The A horizon is most commonly sand, but the range includes fine sand and loamy sand.”

(iv) If there is no known range in a particular characteristic, do not repeat the information provided in the typical pedon.

(v) Preferred expressions are:

  • “typically” or “in some pedons” rather than “frequently ” or “occasionally;”
  • “some pedons” rather than “some places”, (For example, “The lower part of the fragipan in some pedons has evidence of illuviation.”);
  • “is” or “are” rather than “may be;”
  • “2C horizon” rather than “2C material;”
  • “bedrock” rather than “R” layer;
  • “BC horizon” rather than “BC;”
  • “Some pedons do not have a BC horizon” rather than “The BC horizon may be missing;”
  • “the upper part of the B horizon” rather than “the upper B horizon;”
  • “interfingering of albic materials into the Bt horizon” rather than “interfingering of the albic horizon into the argillic horizon;” and
  • “a thin stone line is at the boundary between the two materials” rather than “a thin stone line separates the two materials.”

Use terms for diagnostic horizons or features in this section. If you use the terms, specify their relationship to the horizons and subhorizons of the typical pedon.

(f) Competing series

This section discusses the distinctions between the soil series being described and its major taxonomic competitors. It lists all the soil series of the same family and gives the principal differentiating characteristics that set them apart from the series being described. Because the properties that govern the classification of the soil series being described have already been stated, this section emphasizes those features that distinguish it from the competing series. The comparisons are as specific and quantitative as available information warrants. Comparisons may include reference to diagnostic horizons and other features.

(1) List all soil series in the same family in alphabetical order. List tentative soil series if the series being described is tentative. If the soil series being described is established, list tentative series if they are identified as tentative. Individually state the differentiating characteristics for those soil series in the order of listing unless some can be grouped together and differentiated. If no soil series are in the same family, list series that are in similar families and their differentiating characteristics.

(2) Features that are used to differentiate or group soils include, but are not limited to:

  • the presence or absence of a diagnostic horizon or feature,
  • the texture in some part of the series control section, (the range is given in percent of soil separates),
  • carbonates above or within a specified depth,
  • depth to a lithic or paralithic contact,
  • content or type of fragments in the soils,
  • soils that are redder or yellower than a specified hue,
  • redoximorphic features that have low chroma within a specified depth,
  • soil temperature differences,
  • the thickness of the subsoil,
  • the thickness of the epipedon,
  • soil moisture differences, and
  • reaction in the series control section.

(3) Change the following for preferred expressions:

  • in indicating that a soil has a mollic epipedon, change “thicker darker surface horizon” to “Gamma soils have a mollic epipedon;”
  • in distinguishing a soil that does not have a mollic epipedon, change “light colored surface” to “Gamma soils have an ochric epipedon;”
  • “lower subsoil” to “lower part of the subsoil;”
  • “are redder” to “have hue redder than 10YR;”
  • “soils lack argillic horizons” to “soils do not have an argillic horizon;”
  • “soils have higher organic matter” to “soils contain more than __ percent organic matter;”
  • “have siltier textures in the upper subsoil” to “contain more than __ percent silt in the upper part of the subsoil;”
  • “lower value” to “colors of lower value than;”
  • “moist value” to “moist color value;”
  • “small proportion” to “small part;”
  • “have up to and including 10 cm” to “have as much as 10 cm;”
  • “strongly developed horizons” to “strongly expressed horizons;” and
  • “Gamma soils have argillic horizons with fine-silty textures” to “Gamma soils have a fine-silty argillic horizon.”

(g) Geographic setting

The items in this section include landform or forms, relief, nature of regolith, climate, and any landscape features that are especially helpful in identifying the soils of the soil series. Indicate the name or names of the landform(s) and the range in slope gradient, kind of slope, and aspect for the soils of the series. Record landscape features that mark areas of the soils, for example, common outcrops of rock, an erosional surface, or a depositional surface, in this section.

(1) Briefly describe the nature of the regolith in which the soils formed. Also list underlying rock. The purpose of this statement is to characterize the regolith as an aid in identifying the soils rather than to define the soil series in the terms of underlying rock and mode of accumulation of the regolith.

(2) Characterize climate in terms of temperature, precipitation, and indices. For example, express PE index as a range for the soil series. Only use indices that have been defined in widely available publications. Give information on climate in the descriptions of soil series. Give the range in the number of frost-free days if pertinent. The statements should apply to the section on setting and not to information on soil temperature and soil moisture that is given in the range of characteristics. If pertinent, give the range in elevation.

(3) Preferred expressions include:

  • “Gamma soils are nearly level” rather than “Gamma soils occur on nearly level,”
  • “The soil formed in calcareous” rather than “The soil developed in calcareous,”
  • “Annual temperature” rather than “Annual air temperature.”

(h) Geographically associated soils

Use the list of geographically associated soils to inform users of the names of soil series in the same locality. For example, describe the actual geographic location of the series and how they differ. List the geographically associated soil series, and include a brief comment to distinguish each of them from the series being described. Relate the landscape positions of the associated soil series. The comments do not clearly differentiate soil series but rather highlight major distinctions. Do not repeat the differentiae that are used in the section on competing soil series. A preferred expression for “associated landscapes” is “nearby landscapes.”

(i) Drainage and saturated hydraulic conductivity

Give soil drainage for each soil series, usually as a drainage class or classes. For some soil series, include segments of two adjacent drainage classes. Give the sequence of soil water states in addition to drainage class if it is a more useful way to record moisture regimes. Also include the characterization of saturated hydraulic conductivity in the section. Consider saturated hydraulic conductivity to a depth of 180 cm or to bedrock and describe it according to major changes, for example, "high in the upper part and moderately low in the lower part." Always cite very high saturated hydraulic conductivity in the lower part of the profile. Also give runoff in this section. If it is important, describe runon in this section. If needed, also give statements about flooding in this section. Avoid expressions such as "well drained to moderately well drained". Instead use "well drained or moderately well drained" or "well drained and moderately well drained". Do not assign more than two drainage classes to a soil series

Examples of statements for drainage, runoff, and saturated hydraulic conductivity are:

  • Well drained. Medium runoff. Moderately high saturated hydraulic conductivity.
  • Moderately well drained; low runoff; moderately low saturated hydraulic conductivity. The soils are flooded for short periods in early spring.
  • Well drained. Runoff is medium on the gentle slopes and high on the steeper slopes. Saturated hydraulic conductivity is moderately high in the subsoil and low in the underlying material.

(j) Use and vegetation

List the major uses of the soil series in this section. If soils are used for crops, pasture, or forests or for urban or other uses, indicate the uses along with the general extent of each, if known. Do not discuss productivity levels, yields, limitations, or hazards. Also describe the native vegetation in this section if it covers an important part of the soil. If known, give the various plant communities in successive stages. Refer to an ecological site if known. For some soil series, the kind of native vegetation is uncertain and no longer important because of current use. Do not describe the vegetation for these series. The description is brief since it is meant simply to aid in identifying the soils.

A preferred expression for “Soils are under cultivation with corn and wheat, the principal crops” is “Soils are cultivated. Corn and wheat are the principal crops.”

(k) Distribution and extent

Indicate the extent of the soils of a soil series one of the three classes. The names and extent figures for these classes are given below. Use either the substantive and adjective forms of the name, depending on which is more appropriate for the text. The terms and the extent ranges are as follows:

  • small extent or not extensive----less than 10,000 acres,
  • moderate extent or moderately extensive----10,000 to 100,000 acres, and
  • large extent or extensive----more than 100,000 acres.

Supplement the designation of classes for soil series with extent figures when the soil series is not extensive and when the soil series is of large extent. Examples are:

  • “The soils of this series are not extensive; their total extent is about 6,000 acres.”
  • “The soils of this series are of large extent, about 200,000 acres in size.”

(l) MLRA Office Responsible

Use this heading to indicate which MLRA Office has responsibility for maintenance of this OSD. Check the entry against a like entry in the Soil Classification (SC) file at the time of updating. Format of the entry should be: e.g., Portland, Oregon.

(m) Soil series proposed or series established

Use one of these headings, depending on the current status of the series. For tentative series, the place where the soil series was proposed and the date when the series received tentative status follow the side heading “Series Proposed.” For established soil series, the place and date of establishment follow the side heading “Series Established.” Give the names of the county and state and the year in which a soil series received tentative status or was established. If the survey area is a geographical or political subdivision other than a county, include the name of that subdivision. Give the source of the name for a soil series in the first description of a newly proposed series. A revised description does not need to include the source of the name if it has been recorded in an earlier description.

(n) Remarks

List the horizons and features that are considered diagnostic for the pedon described. The objective is a list of the features needed to classify and characterize the series. Restrict other remarks to those that can help in identifying soils of the soil series as it is currently conceived. For example, a proposal of a new soil series for soils originally from an already established series can be included in the “Remarks” section of the description of the new series. List any unresolved problem with defining the soil series or with differentiating it from others.

(o) Additional data

This section lists sources of data, including study thesis information, data from state laboratories, and advance copies of data from unpublished soil survey investigations reports that were used in defining properties of the soil series.
 

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