Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 29, 1999
Publication Date: N/A
Interpretive Summary: The USDA-Natural Resources Conservation Service (NRCS) would like to use the National Resources Inventory (NRI) framework to measure soil quality on a regional scale. Soil quality indicators need to be identified for use with the NRI. We conducted a pilot study using the NRI methodology in the Central and Southern High Plains regions to: 1) identify potential soil quality indicators, and 2) determine how these indicators changed with different land uses. Rigorous statistical analysis indicated that in the Central High Plains, total organic C and total N were most sensitive to land-use. In the Southern High Plains, total organic C and water stable aggregates were most sensitive to land-use. From this study we concluded that there may not be a universal set of soil quality indicators, but rather, different regions of the country may require different indicators. However, if only one soil property was used to monitor soil quality with the NRI, total organic C appears to offer the greatest potential. Development of methods to measure soil quality using the NRI framework will allow scientists, NRCS, and other agencies to fully evaluate changes in soil resources at a national scale.
Technical Abstract: Appropriate indicators for assessing soil quality on a regional scale are unknown. Our objectives were to: 1) identify soil quality factors present at a regional scale, 2) determine which factors vary significantly with land-use, and 3) select soil attributes within these factors that can be used as soil quality indicators for regional scale assessments. Ascalon (Fine-loamy, mixed, superactive, mesic Aridic Argiustoll) and Amarillo (Fine-loamy, mixed, thermic Aridic Paleustalf) soils were sampled from a statistically representative subset of National Resource Inventory (NRI) sample points within the Central and Southern High Plains Major Land Resource Areas (MLRA) and analyzed for twenty soil attributes. Factor analysis was used 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 soil organic matter and color factors varying significantly with land-use. Discriminant analysis selected total organic C (TOC) and total nitrogen (N) as the most sensitive indicators of soil quality between land-uses at a regional scale. In the Southern High Plains, six factors were identified, with water stable aggregate (WSA) content, TOC, and soil salinity being the most sensitive to land-use. Discriminant analysis selected TOC and WSA content as the most sensitive indicators of soil quality in the Southern High Plains. Our results indicate that across regions, TOC was the only indicator that consistently showed significant differences between land-uses.