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soil resources (Subject) / soils dominated by parent material (Lesson)
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- out of quarz rich material you get... sandy soils -> Arenosols
- from vulcanic parent material you get.... allophane (Andosols)
- from primary minerals you get ... clay minerals -> smectites and vertisols
- characeristics Arenosols arena = sand sandy soils wihtout any development / weak development sandy soils cover large areas and sandytexture caueses special characteristics
- Arenosols of the dry zone developing on shifting sand and dunes minimal soil delopment because of wind erosion divers mineralogical compition -> with gypsum or carbonates rich in bases like K, Mg and Ca
- Arensols in temperate zone... more devloped soil than in arid zone first signs of podzolation on fluvio-glacial, alluvial,lacustrine or eolian and sandy sediments often deepley decalcified low content of bases due to sandy texture low CEC
- Arneosols of humid tropics young soils on eolian or alluvial deposits or old soils with only quarz left -> lost all minerals
- physical caracteristics and management of Arenosols very permeable for water low water holding of only 5-12% loose single grain structure -> sensitive to wind erosion many single dosis when fertilized
- Volcanic parent material - grouped into 3 steps according to their silica content Rhyolite 65-75% Sio2 Andesite 55-65% Basalt 45-55%
- volcanic soils characteristics: Volcanic Soils• Volcanic rocks contain volcanic glass that weathers easily.• Soils developed on volcanic materials are classified as andosols or andisols.• Excellent physical properties.• High content of organic matter• Very high sorption capacity for P !!! (due to the abundance of short-range ordered minerals)
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- Andosols Phsphate holding 85% or more andic properties are result f rapid weathering of volcanic glasses and formtion of poorly cristalline, amorphs or gellike minerals Allophane ...
- Allophane Small globes made up of an Al-oxide octaeder on the outside and a fragmentary Silicate tetraeder on the inside. Can contain a lot of water on the inside!
- use of Andosols very fertile soils high porosity and goood drainage and at the sime time good water holding capacity little risk of water erosion problems P-fixation and limites recycling of organic matter and nutrients Al--toxicity in acidic , Alic andosols