Degradation of Argillic Horizons in Udalf Soils of New York State

Abstract

Interfingering of albic material into the upper part of argillic horizons in Udalfs of New York is interpreted as evidence of degradation by loss of clay proceeding from the top of the horizon downward and from the surfaces of peds inward. These conclusions are based on: (i) albic material lacking oriented clay surrounding ped centers that contain oriented clay; (ii) the volume of albic material decreasing with depth; and (iii) the albic interfingering being least in soils in which high carbonate content is believed to have delayed clay translocation or weathering. The absence of clay skins in the degrading zone—in contrast with thick clay skins rich in fine clay at the Bt‐C horizon boundary—suggests that part of the clay removed at the top is translocated to the bottom of the B horizon. Smaller amounts of inherited mica clays and larger amounts of vermiculite, intergradient clays, and amorphous material in the clay fractions of degraded zones than in the remainder of B horizons indicates some weathering, but losses by this mechanism are believed small.

Pedogênese de uma seqüência de solos desenvolvidos de arenito na região de Piracicaba (SP)

“…A degradação das argilas tem sido apontada como responsável pelo desenvolvimento do gradiente textural em muitos solos podzolizados (Bullock et al, 1974;Berg et al, 1987;Chartres, 1987;Almeida et al, 1997).…”

Indications of ferrolysis and structure degradation in an Estcourt soil and possible relationships with plinthite formation

“…Redox morPhology was alsoipresent in the peds of the Estcourt B horizon as a grey sandy hypo-alban inside the periphery, followed by yellow mottled quasiferrans further to the interior (Table 2). Bullock et al (1974) also reported juxtapositioned grey and yellow cutans and brown cores in peds of similar soils. This pedofeature is an indication of redistribution of Fe-Mn under specific redox conditions .…”

“…These pedofeatures 'are symptoms of structure degradation. It is ascribed to eluviation (Miller et al, 1971;Bullock et al, 1974), ferrolysis (Bullock et aI., 1974) and inversion (Brinkman, 1970). Redox morPhology was alsoipresent in the peds of the Estcourt B horizon as a grey sandy hypo-alban inside the periphery, followed by yellow mottled quasiferrans further to the interior (Table 2).…”

“…Each of the secondary peds was. subdivided further in three visible cylindrical cutans and a core of the matrix: a 1-4 mm thick black surface layer (organan), juxtapositioned 7-13 mm thick grey layer (hypo-alban), juxtapositioned 7-10 mm thick yellow layer (quasiferran), and a brown core (about 30 mm in diameter) (Bullock, Fedoroff, Jongerius, Stoops, Tursina, & Babel, 1985). Each layer was separated with a coarse wood file.…”

Distribution and genesis of Fahlerden (Albeluvisols) in Germany

“…In soils that have developed under temperate climate, these whitish enrichments of silt on the upper surface of Bt peds are interpreted as a degradation of Bt horizons (Bullock et al, 1974;Langohr and Pajares, 1983).…”