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Registro Completo |
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Biblioteca(s): |
Embrapa Solos. |
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Data corrente: |
22/11/2002 |
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Data da última atualização: |
22/11/2002 |
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Autoria: |
FRANZMEIER, D. P.; NORTON, L. D.; STEINHARDT, G. C. |
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Título: |
Fragipan formation in loess of the Midwester United States |
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Ano de publicação: |
1989 |
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Fonte/Imprenta: |
In: SMECK, N.E.; CIOLKOSZ, E.J. Fragipans: their occurrence, classificacao and genesis. Madison: Soil Science Society of America, 1989. (SSSA. Special Publication, 24). |
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Páginas: |
p.69-97 |
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Idioma: |
Inglês |
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Conteúdo: |
In theMidwest, large areas of soils with fragipans are found in Kentucky, Ohio, Indiana, and Missouri, and smaller areas are found in Illinois, Michigan, Minnesota, Wisconsin, and Kansas. They formed in loess, glacial till, weathered clastic rocks, and weathered limestone. Most of these soils are classified as Fragiudalfs or Fragiaqualfs. THe loess-derived soils are most extensive. They have fragipan horizons (Bx) below argillic horizons (Bt) and may have en eluvial horizon (E or E') between the two B horizons. Fragipans form readily in acid silty and loamy deposits that overlie less permeable material (bedrock, paleosols, or dense till) at a depth of 0.75 to 2.5m where the slope is <12%. In the process of fragipan formation, silicate minerals weather in upperhorizons and release their weathering products to the soil solution. In the winter and early spring, Si-rich solutions leach downward and become perched over the less permeable material. During the summer, trees remove water preferentially to the silicic acid in solution, and the ramaining solution is concentrated in the small pores. As water is removed from these pores, silica precipitates and forms bonds with M-O groups, where O is oxygen and M may be Al, Fe, Mg or Si, on the surfaces of particles around these pores. This bond can bridge between mineral grains. The first bonding is molecular in scale, but with time it can grow large enough to be seen with a scanning electron microscope or even with a light microscope. This bridging is responsible for the... MenosIn theMidwest, large areas of soils with fragipans are found in Kentucky, Ohio, Indiana, and Missouri, and smaller areas are found in Illinois, Michigan, Minnesota, Wisconsin, and Kansas. They formed in loess, glacial till, weathered clastic rocks, and weathered limestone. Most of these soils are classified as Fragiudalfs or Fragiaqualfs. THe loess-derived soils are most extensive. They have fragipan horizons (Bx) below argillic horizons (Bt) and may have en eluvial horizon (E or E') between the two B horizons. Fragipans form readily in acid silty and loamy deposits that overlie less permeable material (bedrock, paleosols, or dense till) at a depth of 0.75 to 2.5m where the slope is <12%. In the process of fragipan formation, silicate minerals weather in upperhorizons and release their weathering products to the soil solution. In the winter and early spring, Si-rich solutions leach downward and become perched over the less permeable material. During the summer, trees remove water preferentially to the silicic acid in solution, and the ramaining solution is concentrated in the small pores. As water is removed from these pores, silica precipitates and forms bonds with M-O groups, where O is oxygen and M may be Al, Fe, Mg or Si, on the surfaces of particles around these pores. This bond can bridge between mineral grains. The first bonding is molecular in scale, but with time it can grow large enough to be seen with a scanning electron microscope or even with a light microscope.... Mostrar Tudo |
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Palavras-Chave: |
Estados Unidos; Solos. |
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Thesaurus Nal: |
fragipans. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 02162naa a2200193 a 4500
001 1327881
005 2002-11-22
008 1989 bl uuuu u00u1 u #d
100 1 $aFRANZMEIER, D. P.
245 $aFragipan formation in loess of the Midwester United States
260 $c1989
300 $ap.69-97
520 $aIn theMidwest, large areas of soils with fragipans are found in Kentucky, Ohio, Indiana, and Missouri, and smaller areas are found in Illinois, Michigan, Minnesota, Wisconsin, and Kansas. They formed in loess, glacial till, weathered clastic rocks, and weathered limestone. Most of these soils are classified as Fragiudalfs or Fragiaqualfs. THe loess-derived soils are most extensive. They have fragipan horizons (Bx) below argillic horizons (Bt) and may have en eluvial horizon (E or E') between the two B horizons. Fragipans form readily in acid silty and loamy deposits that overlie less permeable material (bedrock, paleosols, or dense till) at a depth of 0.75 to 2.5m where the slope is <12%. In the process of fragipan formation, silicate minerals weather in upperhorizons and release their weathering products to the soil solution. In the winter and early spring, Si-rich solutions leach downward and become perched over the less permeable material. During the summer, trees remove water preferentially to the silicic acid in solution, and the ramaining solution is concentrated in the small pores. As water is removed from these pores, silica precipitates and forms bonds with M-O groups, where O is oxygen and M may be Al, Fe, Mg or Si, on the surfaces of particles around these pores. This bond can bridge between mineral grains. The first bonding is molecular in scale, but with time it can grow large enough to be seen with a scanning electron microscope or even with a light microscope. This bridging is responsible for the...
650 $afragipans
653 $aEstados Unidos
653 $aSolos
700 1 $aNORTON, L. D.
700 1 $aSTEINHARDT, G. C.
773 $tIn: SMECK, N.E.; CIOLKOSZ, E.J. Fragipans: their occurrence, classificacao and genesis. Madison: Soil Science Society of America, 1989. (SSSA. Special Publication, 24).
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Embrapa Solos (CNPS) |
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