Soils with Plinthite - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 299

Table 25.3 Factors influencing the development of plinthite
Area Factor References

Climate

MS Plinthite formation occurs in

conjunction with Btx
degregration

Aide et al. ( 2004 )

Brazil Tropical, subhumid climate with

distinct wet and dry seasons
favor plinthite formation

Anjos et al. ( 1995 )

Organisms
Brazil

Plinthite favored by savanna
vegetation

Fritsch et al. ( 2007 )

Relief

GA; Brazil; MS Plinthite forms from

redoximorphism in soil
horizons that are intermittently
saturated

Shaw et al. ( 1997 ), Jacobs et al. ( 2002 ),
Coelho and Vidal-Torrado ( 2003 ),
and Aide et al. ( 2004 )

Brazil Soils on footslopes had the most

redox features and plinthite

Anjos et al. ( 1995 )

GA Plinthite zones favored by perching

of water table

Blume et al. ( 1987 )

NC Platy plinthite forms on level

landscapes and nodular
plinthite on sloping landscapes

Daniels et al. ( 1978 )

Plinthite forms in somewhat poorly
to poorly drained portions of
the landscape

Osher and Buol ( 1998 )

Parent material

Brazil Plinthite forms in ferruginous

sandstone

Anjos et al. ( 2007 )

Brazil Low-activity clays susceptible to

plinthite formation

Anjos et al. ( 1995 )

Brazil Plinthite often associated with

kaolinite, hematite, goethite
mineralogy

Coelho and Vidal-Torrado ( 2003 )

Time

Italy Plinthite forms in 100,000 yr Costantini and Priori ( 2007 )

25.7 Summary

Plinthite is defined in ST as an iron-rich, humus-poor mixture of clay with quartz and
other minerals. Plinthite forms by segregation of iron, which probably has been added
from other horizons or from the higher adjacent soils. Plinthite commonly forms in a
horizon that is saturated with water for some time during the year. Plinthite is very
acidic and low in SOC, has a very low cation-exchange capacity (i.e., low activity
clays), and has abundant Fed but low levels of Al d . There are 45 soil series in the