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..