1. ESPM 120 Soil Characteristics Fall 2005

4. 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)

5. Dokuchaev and the founders of Russian pedology

6. 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

7. 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

8. The Mississippi Report Detailed discussion of soil formation and soil chemistry “soil” map of state….

9. Hilgard’s Agricultural Map analogous to modern generalized soil map Map units based on geology and vegetation

10. Hilgard Moves to California Recruited by UC president in 1874 Replaced first chair of agriculture (who was fired)

11. Berkeley when Hilgard arrived…. Despite cultural isolation Hilgard seized opportunty to expand College of Agriculture (now CNR) and make soils a national issue

12. Hilgard and John Wesley Powell (USGS) Prodded JW Powell to start a national soil survey program (later adopted by USDA)

13. 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……

14. Hans Jenny and Soil Formation soils form predictably in response to environmental factors (Dokuchaev ~ 1880) Hans Jenny (1920’s to 1930’s) transformed conceptual model to a more quantitative theory following tenets of physical chemistry

15. State Factor Equation Soil = f (initial conditions, external conditions, time) or, based on field observation Soils = f (climate, biota, topography, parent material, time, …. )

16. 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