Field and 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. Key to the advancement of this body of knowledge has been the cumulative effort of several generations of scientists in developing methods, designing and developing analytical databases, and investigating soil relationships based on these data. Methods development result from a broad knowledge of soils, encompassing topical areas of pedology, geomorphology, micromorphology, physics, chemistry, mineralogy, biology, and field and laboratory sample collection and preparation. The purpose of this manual, the "Soil Survey Field and Laboratory Methods Manual, Soil Survey Investigations Report (SSIR) No. 51," is to (1) serve as a standard reference in the description of site and soils sampling strategies and assessment techniques and (2) provide...

For any measurement program that collects analytical data over a long period of time for comparative purposes, the quality and credibility of those data are critical (Taylor, 1988). It is equally critical that the data can be easily understood by the user. The uses of these data include, but are not limited to, routine soil characterization, special analyses, soil classification, interpretations, and soil genesis and geomorphology studies. Because of the diverse uses of these data, it follows that pedon characterization data, or any soil survey data, are more appropriately used when the operations for collection, analysis, and reporting of these data are well understood. Results differ when different methods are used, even though these methods may carry the same name or concept. Comparison of one bit of data with another is difficult without knowing how both bits were gathered. As a result, operational definitions have been developed and are linked to specific methods.