ESPM 120 Soil Characteristics

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ESPM 120Soil Characteristics

• Fall 2005

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History of Pedology

• mid 19th Century no scientific study of soils
• Soil science followed closely behind development
  of geology (early 19th century) and biology
  (Origin of Species).
• Two key contributors to development of Pedology
• Vasili Dochuchaev (Russian geographer/mineralogist
  )
• Eugene Hilgard (American geologist/chemist)

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Dokuchaev and the founders of Russian pedology
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Eugene Hilgard and Soil Science at Berkeley

• Born in Germany
• Raised in American frontier (Illinois) in
  intellectually oriented family
• Received PhD at University of Heidelberg
• Agricultural chemistry and geology
• Accepted position as Assistant State Geology of
  Mississippi in 1855

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Hilgard in Mississippi

• Not a glamorous job
• Recognized his future with state lie not with
  geology but agriculture and soils
• Produced a landmark document (next slide) with
  half geology and half soils

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The Mississippi Report

• Detailed discussion of soil formation and soil
  chemistry
• soil map of state.

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Hilgards Agricultural Map

• analogous to modern generalized soil map
• Map units based on geology and vegetation

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Hilgard Moves to California

• Recruited by UC president in 1874
• Replaced first chair of agriculture (who was
  fired)

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Berkeley when Hilgard arrived.

• Despite cultural isolation Hilgard seized
  opportunty to expand College of Agriculture (now
  CNR) and make soils a national issue

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Hilgard and John Wesley Powell (USGS)

• Prodded JW Powell to start a national soil survey
  program (later adopted by USDA)

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Hilgard and his legacy.

• Mountains, lakes, streets, buildings, journals
  are all named after Hilgard
• His influence was international, inspiring the
  next generation of scientists, particularly Hans
  Jenny

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Hans Jenny and Soil Formation

• soils form predictably in response to
  environmental factors (Dokuchaev 1880)
• Hans Jenny (1920s to 1930s) transformed
  conceptual model to a more quantitative theory
  following tenets of physical chemistry

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State Factor Equation

• Soil f (initial conditions, external
  conditions, time)
• or, based on field observation

Soils f (climate, biota, topography, parent
material, time, . )
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Key Concepts of State Factor Theory

• Factors are independent of system
• System is small relative to surroundings
• A change in variables defines a new system
• there are essentially an infinite number of soils