Chapter 2 - continuation

• Rock & Soil

  Material that serves as an interface between the atmosphere, lithosphere and hydrosphere
• Soil formation


  Combined effect of physical, chemical, and biotic forces acting on organic and weathered rock fragments
• Rock & Soil

  Natural body of mineral and organic material formed in response to environmental factors and processes
• Soil horizon(distinct soil)


  Distinct layer that lies one above the other, parallel to the soil surface
• O horizon(organic)


  • Rich in organic material of plant and animal origin
  • various stages of decomposition
  • HUMUS : decomposed organic material
  • undecomposed or patrial decomposition litter : leaves/twigs
• A horizon (topsoil) (biomantle) (mineral H)

  • darker in color
  • where most biological activities take place
  • accumulated of humified organic matter intermixed with mineral function
• B horizon


  • Also referred to as subsoil
  • rich in clay and minerals like iron or aluminum
  • organic material: reach by leaching
  • plant roots reach this layer
  • reddish/brownish due to: oxides of iron & clay
• C horizon(regolith)

  • made of large rocks or lumps of partially broken bedrock
  • least affected by weathering
  • inaccessible to the soil forming agents
  • plants do not reach
  • devoid of organic matter
• Types of soil

  • Oxisols
  • Aridisols
  • Mollisols
  • Alfisols
  • Ultisols
  • Spodosols
  • Entisols
  • Inceptisols
  • Vertisols
  • Histosols
  • Andisols
  • Gelisols
• Oxisols (tropical area)

  • intensely weathered
  • yellow to red in color
  • low nutrient retention
  • no distinct horizons, very deep
  • various crops can grow but fertilizer is needed
  • oxi - oxide
• Aridisols (dry soils of desserts)

  • do not receive enough rain for normal agriculture
  • clay enriched subsoil
  • WHITE AREA: calcium carbonate / limestone
• Mollisols (great for agriculture)

  • dark surface
  • enriched with organic matter
  • naturally fertile
  • hold large amounts of water
  • prized for agriculture
  • SURFACE LAYER: soft, fluffy feel
  • FORMED FROM : nutrient rich parent materials, commonly in grasslands
• Alfisols(forested soil)

  • Form in semiarid to humid areas
  • have clay enriched and nutrient enriched subsoil
  • vegetative cover
  • productive if conserved
  • degraded rapidly if eroded
• Ultisols(easy to bungkal)


  • Highly weathered and low in nutrients
  • lower pH and organic matter than Alfisols
  • reddish in color
  • Latin ultimus = ultimate
  • Surface soil: coarsest-textured easy to till
  • stored water for plant roots
• Spodosols(wood ashes)


  • dark surface layer
  • underlain by a light eluvial horizon, acid and generally under forests
  • careful water & fertility management
  • very sandy
  • spodos = wood ashes
• Entisols(immature soils) (young)


  • lack the vertical development of horizons
  • associated with recently deposited sediments
  • eut = recent
• Inceptisols(beginning stage of soil formation)


  • Altered horizons
  • not weathered enough to become illuvial horizon
  • Inceptum = beginning
  • shallow bed rock
  • occur steeply sloping land
• Vertisols(can damage bldgs. & roads)


  • shrink and develop cracks when dry and swell when moist
  • Vertare = turn over
  • mineral montmorillonite in the clay fraction causes this property
• Histosols(tissues)


  • Dark soils
  • slightly decomposed to well decomposed organic materials
  • poorly drained and occur in low-lying areas
  • histos = tissues
• Andisols(volcanic ash)

  • commonly : land surrounding pacific rim
  • Ando = Black (japanese)
  • High porosity (& of volume hot occupied by solid material)
  • particle surface area & water holding capacity
• Rocks


  • Earth's lithosphere
  • composed of one or more minerals to form cohesive solid
• Weathering


  Changes in rocks brought about by exposure to air, water, changing temperature, and reactive chemical agents
• Types of weathering

  • Mechanical/Physical
  • Chemical
• Soil characteristics vary depending on:

  • type of bedrock/parent material
  • type of vegetation
  • climate
  • topography
  • age of soil
• Inorganic chemical substances

  • Acids
  • Bases
  • Salts
  • Water
  • Carbon dioxide
• Organic chemical substances

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic Acids
• Acids

  • requisites in biological systems
  • sustain life to some organisms
• Bases


  • alkaline substances
  • buffer acidic substances
• Salts


  • ionic compounds that result from neutralization reaction of an acid and a base
• Water


  • Most essential component of life
  • Universal Solvent - medium of transport because of its properties as a solvent
• Hydrosphere consists about 71% of water
• Carbon dioxide

  • naturally occurring chemical compound composed 2 oxygen atoms covalently bonded to a single carbon atom
  • part of carbon dioxide cycle
  • by product of combustion
• Major organic substances in biological systems

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic acids
• Organic substances


  • Materials that contain large amounts of carbon in combination with hydrogen and oxygen
  • essential in the make-up of life
• Carbohydrates


  • Hydrates of carbon or saccharides
• Proteins


  • Made of amino acids
  • arranged: linear chain
  • joined : peptide bonds
  • enzyme that catalyze the chemical reactions in metabolism
• Lipids


  • Molecular organic compounds
  • composed largely: carbon & hydrogen
  • non-soluble in water
  • "fats"
• Lipoproteins


  Combination of fat and protein
• Cholesterol


  Naturally occurring substance in the body and is comprised of lipids
• Nucleic acids


  • Biological molecules essential for life
  • Make up the most of important macromolecules found in abundance in all living things