Quiz 3 - Answers

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• Quiz 3 - Answers
• 1.) T F Conservation tillage refers to
  methods of preparing the soil for planting that
  are more likely to disturb or move soil than
  conventional tillage.
• 2.) T F One thing soil color helps to
  identify is the moisture regime of a soil.
• 3.) a. What textural class is a soil with 10
  clay and 60 sand?
• sandy loam
• b. What silt would this soil have?
• 30 silt
• c. Can you change a soils textural class by
  adding organic matter?
• No
• d. Why or why not?
• Soil texture is a property referring only to
  the mineral particles therefore organic matter
  plays no part in determining a soils textural
  class.
• 4.) What is the pore space of a typical mineral
  soil having a Db of 1.05 Mg/m3? 60.4 pore
  space
• 5.) What did you learn about bulk density from
  the Sharratt article?
• Some possible answers In areas of compaction,
  bulk density can be higher. Bulk density did not
  account for a thinner A horizon. The effects of
  compaction causing greater bulk density can last
  for 100 yrs.

(1) (1) (4) (2) (2)
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• http//nature.berkeley.edu/classes/espm-120/

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Photo of Soil ProfileClassification Typic
Haplohumult
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REVIEWProcesses of Soil Formation
CO2 flux

• Additions
• Organic C
• Dust
• Removals
• CO2
• Weathering products
• Transfers
• Clay
• Organic matter
• Carbonate
• Transformations
• Plants to SOM
• Primary silicates to secondary silicates,
  carbonates

OM additions, OM transformations, weathering
Clay transfers
Clay and carbonate transfers
Leaching
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Soil Horizon Nomenclature

• Based on interpretation of dominant soil forming
  processes affecting that horizons
• Names based on presumed changes relative to
  parent material (t0)
• Universal with some variance
• Originated by Russians in 19th Century

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Master Horizon Nomenclature
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Example
A
Bt
Btqm
BC
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Master Horizon Subdivisions
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Chapter 3Soil Classification

• It is embarrassing not to be able to agree on
  what soil is. In this the pedologists are not
  alone. Biologists cannot agree on a definition
  of life and philosophers on philosophy.
• -Hans Jenny
• from The Soil Resource Origin and Behavior

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Classification

• Pedon the smallest volume that can be called a
  soil
• Polypedon two or more contiguous pedons, also
  called soil individual
• Landscape region, tract of land
• Figure 3.1

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Classification

• Genetic horizon soil layers resulting from
  soil-forming processes (pg. 73)
• presence or absence help classify soil
• Diagnostic horizon soil layers having specific
  soil characteristics indicative of certain
  classes of soils
• at surface epipedon
• below surface diagnostic subsurface horizon
• Figure 3.4

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