Publikationsdatum:
2001-08-01
Beschreibung:
The nature of parent materials strongly influences soil development in the southeastern US Piedmont. In this region, most parent materials (saprolite) form from metamorphic and igneous felsic and mafic rocks. Although most soils in felsic terrains are acid and kaolinitic, soils formed from mafic parent materials range from kaolinitic Ultisols to Alfisols with smectite. Because it is sometimes difficult in soils developed in mixed terrains to determine parent material influence, exchangeable Ca/Mg ratios were used to elucidate soil-parent material relationships. Establishment of Ca/Mg signatures diagnostic of soil-parent material suites could facilitate soil mapping activities and forest fertilization regimes. Characterization data collected as part of the National Cooperative Soil Survey (mainly Georgia and Alabama) were evaluated, and soils were grouped by parent material type. The Ca/Mg ratios did not prove to be diagnostic for separating parent materials; however, significant depth trends existed. In most of the groupings, Ca/Mg ratios decreased with depth in the solum, which was most likely due to selective retention of Ca2+ and the effects of bio-cycling. The ratio either increased below the solum (mafic soils), or continued to decrease (felsic soils). Thus, these ratios are useful for identifying solum depth in some of these soils. The (Ca + K)/Mg ratios were more diagnostic with regard to parent material. These data suggest soils possessing ratios of (Ca + K)/Mg 〈 2 within the solum (excluding surface horizons) have been significantly influenced by mafic parent materials. Key words: Piedmont, Ca-Mg ratios, Ultisols, Alfisols, pedogenesis
Print ISSN:
0008-4271
Digitale ISSN:
1918-1841
Thema:
Geologie und Paläontologie
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Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
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