Download Data/hora: 06/05/2017 14:31:12 Biblioteca(s): Embrapa Cerrados

Data/hora: 08/06/2017 17:28:27
Biblioteca(s): Embrapa Cerrados.
Data corrente: 04/02/1997
Data da última atualização: 04/02/1997
Autoria: GOMES, I.A.
Título: Oxisols and inceptisols from gneiss in a subtropical area of Espirito Santo State.
Ano de publicação: 1976
Fonte/Imprenta: [s.l.]: Purdue University, 1976.
Páginas: 115p.
Idioma: Inglês
Notas: Msc. Thesis.
Conteúdo: A study was conducted to gain information on the genesis, classification and management
of certain soils from a subtropical area of Brasil. The objective was accomplished by
studying the physical, chemical and mineralogical properties substantiated by the
morphological descriptions of the six soil profiles. The soils occupy steep slopes in the
Crystalline Plateau of the state of Espirito Santo, whitch receives a relatively high rainfall.
The climate is subtropical due to the altitude, which varies between 500 and 1300 meters.
One part of the area is always humid and another part shows a short dry season. The mean
annual precipitation ranges from 1200 to 2000 mm and the mean annual temperature
ranges from 18 to 20ºc. The parent material of the soils is a deeply weathered material,
generally transported in its landscape, derived from acid gneiss. Quartz, kaolinite and/or
gibbsite, and goethite are the main minerals present in all profiles. Also, muscovite and
slightly altered biotite (micaceos material with paler colors and broadening of 10º A peak
of biotite to around 11ºA) occur in noticeable amounts in two profiles. The sand fraction
of most profiles shows high amounts of quartz. The content of quartz sharply decreases in
the silt fraction and reaches the breakdown point in the clay fraction. The fine silt fraction
(20 to 2) is dominated by kaolinite and gibbsite in all profiles. Kaolinite, gibbsite and
goethite are the main minerals in the clay fraction of all profiles. Kaolinite, has been
mainly formed by alteration of micas, and is seen in the sand fraction of most profiles as a
pseudomorph of kaolinite after mica. Biotite gives rise to kaolinite through two stages:
Biotite- slightly altered biotite - pseudomorph of kaolinite. Gibbsite occurs in high
amounts in areas which have a short dry season or in slightly drier ones. Iron oxide
aggregates occur in the coarser fractions of every profile and are composed of gibbsite
and quartz coated by amorphus iron oxides and/or goethite. Additions of organic matter,
losses of silica and bases. and transformations of primary minerals to kaolinite, gibbsite
and iron oxides are the major soil forming processes in these soils. The soils have an
ochric epipedon. Most of them have an oxic horizon and some have a cambic horizon.
The soils were classified as Oxisols, Inceptisols and intergrades between Oxisols and
Inceptisols. Proposals were made for additions of Ochreptic Haplohumox and Ochreptic
Acrorthox subgroups in the Soil Taxonomy.
Palavras-Chave: Brasil; Brazil; Classificacao; Espirito Santo; Ferrasols; Fisica do solo; Inceptsols; Manejo
do solo; Mineralogia; Oxisol; Quimica do solo; Regiao tropical; Soil chemicophysical
properties; Soil chemistry; Soil classification; Soil management; Solo; Tropical zones.
Categoria do assunto: -Registro original: Embrapa Cerrados (CPAC)
Exemplares: CPAC - (13442-1) - ADD - TS - -- - T002/76 - GOM - T002/76 - DIS