Identification of regional soil quality factors and indicators: I. Centraland southern high plains

Appropriate indicators for assessing soil quality on a regional scale using the National Resource Inventory (NRI) are unknown. Oar objectives were to (i) identify soil quality factors present at a regional scale, (ii) determi ne which factors vary significantly with land use, and (iii) select soil at tributes within these factors that can be used as soil quality indicators f or regional-scale assessment. Ascalon (fine-loamy, mixed, superactive, mesi c Aridic Argiustoll) and Amarillo (fine-loamy, mixed, thermic Aridic Paleus talf) soils were sampled from a statistically representative subset of NRI sample paints within the Central and Southern High Plains Major Land Resour ce Areas (MLRA) and analyzed for 20 soil attributes. Factor analysis was us ed to identify soil quality factors, and discriminant analysis was used to identify the factors and indicators most sensitive to land use within each MLRA. In the Central High Plains, five soil quality factors were identified , with the organic matter and color factors varying significantly with land use. Discriminant analysis selected total organic C (TOC) and total N as t he most sensitive indicators of soil quality at a regional scale. In the So uthern High Plains, six factors were identified, with water stable aggregat e (WSA) content, TOC, and soil salinity varying significantly with land use . Discriminant analysis selected TOC and WSA content as the most sensitive indicators of soil quality in the Southern High Plains. Total organic C was the only indicator that consistently showed significant differences betwee n land uses in both regions.