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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