This collection contains air-dried soil samples collected during distributed initial soil characterization at NEON terrestrial sites (NEON sample class: spc_perbiogeosample_in.archiveID). Sampling was conducted by the Soil Science Division of the Natural Resources Conservation Service (NRCS), in partnership with the USDA Agriculture Research Service (ARS) on behalf of NEON. At each site, up to 4 Tower and 30 Distributed plots were sampled, based on site variability and number of soil map units present. In most Distributed base plots, a single 1 m x 1 m x 1 m soil pit was excavated. In Tower plots and sites where pit sampling was not permitted, several 10 cm diameter, 1 m deep cores are collected from within a 1 m x 1 m square (where possible). Upon excavating a pit or collecting cores, the NRCS described the profile and all major horizons, assessed coarse fragment volumes, collected bulk density samples (most often by the clod method), then collected enough material to conduct all physical and geochemical laboratory analyses. If sufficient air-dried material was available upon completion of all measurements, it was placed into archive for community use. See link below for the NEON data product that provides soil taxonomy, physical, and geochemical measurements, and website links for how to request these soils from the external collection as they are not stored at the NEON Biorepository.