The National Forestry Handbook (NFH) contains methodology, procedures, and related reference materials that assist NRCS personnel to implement the policies contained in the National Forestry Manual (NFM) relative to forestry and agroforestry technologies. All references to the Soil Conservation Service or SCS by Public Laws, Memoranda or other documents stated herein have been changed to the Natural Resources Conservation Service or NRCS, respectively. All policies and responsibilities relating to forestry previously assigned to the Soil Conservation Service are carried forward in full to the Natural Resources Conservation Service unless otherwise noted or amended in this handbook. Illustrations in full color and black and white.

Laboratory data are critical to the understanding of the properties and genesis of a single pedon, as well as to the understanding of fundamental soil relationships based on many observations of a large number of soils. Development of both an analytical database and the soil relationships based on those data are the cumulative effort of generations of soil scientists at the Soil Survey Laboratory (SSL). The purpose of the Soil Survey Investigations Report (SSIR) No. 42, Soil Survey Laboratory Methods Manual is to document methodology and to serve as a reference for the laboratory analyst. It is expected that this document will continue to evolve and change over time as new methods are developed and old methods are modified or retired based on new knowledge or technologies. This manual is an historical document in that it describes both current and obsolete methods at the SSL. This manual also provides historical perspective, documenting the contributions of many soil scientists who have gone before us. Many of these scientists are noted in the section on contributors. Illustration are in full color and black and white.

The publication Keys to Soil Taxonomy serves two purposes. It provides the taxonomic keys necessary for the classification of soils in a form that can be used easily in the field. It also acquaints users of the taxonomic system with recent changes in the system. The eleventh edition of the Keys to Soil Taxonomy incorporates all changes approved since the publication of the second edition of Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1999). One of the most significant changes in the eleventh edition is the addition of the suborders Wassents and Wassists for subaqueous Entisols and Histosols.

The National Forestry Handbook (NFH) contains methodology, procedures, and related reference materials that assist NRCS personnel to implement the policies contained in the National Forestry Manual (NFM) relative to forestry and agroforestry technologies. All references to the Soil Conservation Service or SCS by Public Laws, Memoranda or other documents stated herein have been changed to the Natural Resources Conservation Service or NRCS, respectively. All policies and responsibilities relating to forestry previously assigned to the Soil Conservation Service are carried forward in full to the Natural Resources Conservation Service unless otherwise noted or amended in this handbook.

The publication Keys to Soil Taxonomy serves two purposes. It provides the taxonomic keys necessary for the classification of soils in a form that can be used easily in the field. It also acquaints users of the taxonomic system with recent changes in the system. The eleventh edition of the Keys to Soil Taxonomy incorporates all changes approved since the publication of the second edition of Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1999). One of the most significant changes in the eleventh edition is the addition of the suborders Wassents and Wassists for subaqueous Entisols and Histosols.