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Laboratory Information Manual Preface
The Soil Survey Laboratory (SSL), National Soil Survey
Center (NSSC) is responsible for providing accurate and reliable soil
characterization data for the National Resources Conservation Service
(NRCS) National Cooperative Soil Survey (NCSS) Program.
The SSL data are
provided in reports, e.g., Primary and Supplementary Characterization
Data Sheets and in various electronic forms, including tapes, disks, and
CD-ROMs. These reports are the end product of the analytical system and
are a means to transmit information to the users of these data. It
follows that these data reports must be complete, accurate, and
understandable. In addition, these reports provide historical
documentation for future reference.
Pedon characterization data, or any soil survey data,
are more appropriately used when the operations for collection,
analysis, and reporting these data are thoroughly understood. The
purpose of this document is to describe
the SSL characterization
data reports to maximize user understanding of these data. This document
is not intended as an interpretive guide for soil characterization
data.
Included in this document is a brief discussion of
sampling methodology and its role in soil analysis. While the
definitions, protocols, and applications of the various types of samples
and sampling plans are beyond the scope of this document, the importance
of sampling as a critical step to successful soil analysis is described.
After the discussion on sampling is the description of the SSL Data
Sheets, which includes information about sample origin and
identification, method documentation, general conventions in reporting
data, and finally, a column-by-column explanation of the Primary and
Supplementary Characterization Data Sheets. This document contains an
extensive appendix, which includes example SSL data reports and pedon
descriptions (Appendices I - II); laboratory preparation codes (Appendix
III); soil textural triangle (Appendix IV); example particle-size
distribution and water retention curves (Appendices V - VI); basic
chemistry terminology (Appendix VII); mineralogy codes and methods
(Appendix VIII - X); quality assurance terminology (Appendix XI); data
unit conversions (Appendix XII); and example NRCS-SOIL-8 (Appendix
XIII).
The example pedon descriptions in the appendix are those
made at the time of sampling and therefore may not be uniform in quality
or terminology, as soil description techniques have changed over time.
Field estimates at the time of sampling are in themselves considered
important and have been retained, even though these estimates sometimes
vary with SSL data. The record of what was perceived at the time
of sampling is deemed to be more important than the achievement of
complete editorial uniformity.
The NRCS-SOIL-8 form is a soil data index from which
laboratory data are made available to NCSS cooperators. This index
includes pedon classification, location data (latitude and longitude,
county, soil survey area, and state), data source, and kinds of analyses
available.
Trade names are used in the manual solely for the
purpose of providing specific information. Mention of a trade name does
not constitute a guarantee of the product by the U.S. Department of
Agriculture, nor does it imply an endorsement by the U.S. Department of
Agriculture.
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