QUIZ 6_Answers

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• QUIZ 6_Answers
• 1. Explain how a brush fire might lead to
  subsequent mudslides, as often occurs in
  California. (2)
• Fire can significantly increase surface soil
  temperature
• Volatilize soil organic matter
• These org compounds move down through profile and
  condense on soil particles
• Creates hydrophobic layer
• Rain cannot infiltrate past layer, causes
  saturation of surface with water, increase chance
  for mudslide.
• 2. What are the major components of soil water
  potential? (2)
• gravitational, matric, osmostic
• 3. Describe the gravimetric method of measuring
  soil water content. (2)
• 1. weigh wet soil
• 2. dry the soil
• 3. reweigh the dry soil
• 4. subtract dry soil wt from wet soil wt to
  obtain mass of water
• 5. mass water content (?m) mass water/mass dry
  soil
• 4. The Waddell study used a tensiometer to
  measure the horizontal and vertical distribution
  of soil water pressures in both the ridge-till
  and the no-till system. Figures 4 and 5 showed
  the difference in water potentials between 1)
  right after a rain (Fig. 4) and 2) after seven
  days of drying (Fig. 5). The no-till plots
  showed level horizontal distribution of soil
  water pressures in both figures (decreasing with
  depth), but the ridge-till figures indicated that
  after seven days of drying water pressure was
  highest in the ridge and lowest in the furrows.
• a. What was the direction of water movement in
  the ridge-till plot over that seven day period?
  (2)

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Soil Water continued

• Chapter 5

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Chapter 5 Outline

• I. Review
• II. Journal Articles General Concepts
• III. Waddell Article
• IV. Infiltration/Percolation
• V. Field Capacity/Permanent Wilting

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Table 5.3
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Stratified Soils
Fig 5.28
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Michael J. Singer and Donald N. MunnsSoils An
Introduction, 6e
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wetting front vs preferential flow
Michael J. Singer and Donald N. MunnsSoils An
Introduction, 6e
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Fig 5.35
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Classification of Soil Water http//www.pedosphere
.com/volume01/pdf/section_08_03.pdf
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