B6 Soils

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  • Created by: Qiao-Chu
  • Created on: 12-04-13 10:00
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  • Soils
    • Types of soil
      • Sandy soil
        • Large mineral particles so large pores, high air content, very permeable
      • Clay soil
        • Tiny particles packed tightly, very few pores, low air content and low permeability, retain more water because water molecules cling to particles
      • Loam soil
        • Mixture of sand and clay particles, properties depend on relative amounts of types of particles
      • Other
        • Most soils contain humus - decomposed dead organic matter helps support soil life
    • Experiments to determine structure of soil sample
      • Measure air content
        • 1. Loosely pack sample of soil into beaker or test tube and measure volume
        • 2. Fill pipette with known volume of water and add to beaker gradually, allowing seep into soil
        • 3. Continue until water reaches top of soil sample
        • 4. Find out how much water added, equal to volume of air
      • Measure water content
        • 3. Take mass again, difference is mass of water
        • 1. Take mass of small sample of soil
        • 2. Heat sample to 105 degrees Celsius until constant mass reached, boil off water in soil
      • Measure humus content
        • 1. Take mass of small sample of soil
        • 2. Heat soil sample to 550 degrees Celsius for two hours to burn all humus from sample
        • Take mass again, difference is mass of humus
  • Measure water content
    • 3. Take mass again, difference is mass of water
    • 1. Take mass of small sample of soil
    • 2. Heat sample to 105 degrees Celsius until constant mass reached, boil off water in soil

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