March, 1998                                          SCSB#391

Mineralogical composition is recognized as an important variable in studies of physical and chemical properties of soils. However, mineralogical data have not been fully utilized in the use and management and the interpretation of soils. Two underlying reasons are the uncertainty about characteristics imparted to soils by various minerals, and the lack of mineralogical information for particular geographic areas.

In the Southern Region, only a few of the family mineralogy classes of Soil Taxonomy are used, and some of these classes are broadly defined. The mixed class, for example, includes soils with sufficient amounts of several different minerals that influence strongly chemical and physical properties, and therefore soil use and management. Small percentages of some of these minerals have larger effects than moderate amounts of other minerals.

A definite need exists to determine the geographic distribution of mineral suites in soils of the Southern Region. The variability among states in the mineral composition of soils and characteristics of specific minerals is well documented. Data from many locations need to be compiled so that interpretations can be made regarding the effects various minerals produce. Greater refinement of the mineralogical classes would aid soil classification as well as provide for the efficient use of mineralogical data for agricultural and non-agricultural uses of soils.

Combining existing soil mineralogical data with existing geologic, geomorphic, and soil maps may make it possible to: 1) identify areas of relative soil mineralogical homogeneity requiring minimum future mineralogical investigations for soil survey, 2) identify areas requiring more intense soil mineralogical characterization to fill the needs of soil survey, and 3) provide a more reliable areal basis for the extrapolation of mineralogically related soil interpretations.

This publication is the result of a regional research effort to pool mineralogical data across the region in order to determine ranges for occurrence of soil mineral suites, develop a classification system for these mineral associations, and compile a map showing the distribution of associations of soil mineral classes in the Southern Region.